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THE STONE INDUSTRIES

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THE STONE INDUSTEIES "

Dimension Stone Crushed Stone

Geology Technology Distribution Utilization

OLIVER BOWLES

Supervising Engineer, Bxiilding Materials Section
United States Bureau of Mines

Second Edition

McGRAW-HILL BOOK COMPANY, Inc.

NEW YORK AND LONDON

1939

PRINTED IN THE UNITED STATES OF AMERICA

parts thereof, may not be reproduced

in any form without permission of

the publishers.

THE MAPLE PRESS COMPANY, YORK, PA.

PREFACE TO THE SECOND EDITION

Since the first edition of this volume appeared, the stone industries
have suffered the most severe depression in their history. Now they are
emerging toward a more normal rate of production, and there is definite
prospect of increasing activity in building which should promote further
gains. In this new edition most of the tables have been revised to show
the latest available figures, and corresponding changes have been made in
the text to embody the most recent data.

Centers of production have shown so Httle change during recent years
that only minor corrections were needed. The sections on technology
of quarrying and fabrication as covered in the first edition were based
largely on the author's personal observation and study of hundreds of
quarries and stone-finishing mills, and they reflect modern practice so
comprehensively that little revision was required. Although refinements
in equipment and methods are constantly in evidence, no fundamental
modifications have occurred since 1934; therefore, the portrayal of condi-
tions as set forth in the new edition approximates a true picture of the
stone industries as they exist today.

Oliver Bowles.
Washington, D. C,
January, 1939.

PREFACE TO THE FIRST EDITION

No book adequately covering the stone industries has been available
recently. Building stones were described many years ago by Dr. George
P. Merrill in his well-known volume, Stones for Building and Decoration,
the third edition of which appeared in 1910 and is now out of print.
The venerable doctor was planning a much-needed revision, but his
plans were cut short by his sudden death in 1929. Other books, such as
E. C. Eckel's Buildijig Stones and Clays and C. H. Richardson's volume
of the same title, are valuable for certain phases of the stone industries.
Various bulletins on granites, marbles, and slates by T. Nelson Dale
contain a wealth of detailed information, chiefly of geological import.
Bulletins of several State geological surveys describe the stone resources
and developments of their States quite thoroughly, but few have been
published during recent years. Certain textbooks for engineers and
architects contain brief and frequently quite inaccurate references to
stone as a material of construction. None of the publications mentioned
presumes to cover the many ramifications of the stone industries; the
purpose of this volume is to fill this gap in American technical literature.

The author began his studies of the stone industries in Minnesota in
1912; and during the years since 1914, as a quarry specialist of the
United States Bureau of Mines, he has visited and made intimate exami-
nations of hundreds of quarries and mills scattered throughout many
States. Results of successive detailed studies were embodied in a series
of reports, several of which are now out of print. The background of
first-hand knowledge thus gained was the chief incentive that urged him
toward the laborious task of compiling this book.

Acknowledgment is made to the officials of the United States Bureau
of Mines for permitting wide reference to its published information.
Grateful acknowledgment is rendered to many who have assisted in
preparing the material. In presenting a broad subject in a comprehen-
sive manner innumerable occasions for errors occur, and while mis-
statements may still remain, review by competent authorities and
repeated revisions have greatly minimized this liability. The author
desires to make special mention of noteworthy service by Harold Ladd
Smith of Proctor, Vt.; J. B. Newsom of Bloomington, Ind.; J. L. Mann
and R. M. Richter of Bedford, Ind.; Charles H. Behre of Evanston, 111.;
W. S. Hays of Philadelphia; Lawrence Childs and Jules Leroux of New
York, and Societe Anonyme de Merbes-Sprimont, Brussels, Belgium.
Several quarry operators have kindly reviewed sections of the book

vili PREFACE TO THE FIRST EDITION

relating to their industries. The chapters devoted to crushed and broken
stone involved so much detail regarding deposits and their geology that
the services of State geologists were enlisted for review and comment.
The author desires to express to them his keen appreciation of their
most helpful and hearty cooperation. To Paul M. Tyler, Paul Hatmaker,
and H. Herbert Hughes, associates of the author in the United States
Bureau of Mines, acknowledgment is due for many helpful suggestions.
Miss A. T. Coons of the Bureau, whose intimate knowledge of the stone-
producing industries is widely recognized, supplied valuable comment
and advice. To my wife, Eva H. Bowles, grateful acknowledgment is
made for assistance in proof reading, and to my sons, George and Edgar,
for corrections and revisions of certain sections.

Oliver Bowles.
Washington, D. C.
July, 1934

CONTENTS

Page

Preface to the Second Edition v

Preface to the First Edition vii

Introduction xiii

PART I

GENERAL FEATURES OF THE STONE INDUSTRIES

CHAPTER I
Extent and Subdivision 3

Extent of the Industry — Major Divisions of the Industry — Varieties of
Stone Used

CHAPTER II

Minerals and Rocks 5

Distinction between Rock and Stone — Relation of Rocks to Minerals —
Rock-forming Minerals — Classification of Rocks — General Distribution of
Rocks in the United States

CHAPTER III

Factors Governing Rock Utilization 8

Rock Qualities on Which Use Depends — Importance of Other Factors than
QuaUty — Available Markets — Diversification of Products — Transportation
Facilities — Production Costs

CHAPTER IV

Prospecting and Development II

Prospecting — Stripping— General Methods of Operation — Bibliography

PART II
DIMENSION STONE

CHAPTER V

General Features of Dimension-stone Industries 23

Definition of Dimension Stone — Principal Uses — Requisite QuaUties of
Dimension Stone — Adaptations of Raw Materials to Use — Complexities in
Marketing — Royalties

CHAPTER VI

Limestone 33

Definition: — Origin — Physical Properties — Varieties — Qualities on Which
Use Depends — Uses — Industry by States — Occurrences of Travertine —
Quarry Methods — MiUing Methods — Limestone Products — Cost of Quarry-
ing and Manufacture — Waste in Quarrying and Manufacture — Utilization
of Waste — Limestone Marketing — Bibliography

X CONTENTS

Page
CHAPTER VII

Sandstone 67

Varieties — Composition — Size and Shape of Grains — Cementation — Color —
Porosity — Uses — Production — Industry by States — Quarry Methods —
Quarry Processes — Yard Service — Sandstone Sawmills and Finishing Plants
— The Bluestone Industry — Waste in Sandstone Quarrying and Manufac-
ture— Bibliography

CHAPTER VIII

Granite 103

General Character — Mineral Composition — Chemical Composition — Physi-
cal Properties — Varieties — Related Rocks — Structural Features- — Uses —
Distribution of Deposits — Industry by States — Quarry Methods and Equip-
ment— Milling Methods and Equipment — Market Range — Imports,
Exports, and Tariffs — Prices — Bibliography

CHAPTER IX

Marble 168

History — Definition — Composition — Origin and Varieties — Physical Prop-
erties— Jointing or Unsoundness — Chief Impurities of Marble — Uses — Dis-
tribution of Deposits — Production — Industry by States — Quarry Methods
and Equipment — Transportation — Equipment and Operation in Mills and
Shops — Waste in Quarrying and Manufacture — Marketing Marble —
Imports and Exports — Tariff — Prices — Bibliography

CHAPTER X

Slate 229

Definition — Origin — Mineralogical Composition — Chemical Composition —
Physical Properties — Structural Features — Imperfections — Uses — History
of Industry — General Distribution — Production — Industry by States —
General Plan of Quarrying — Quarry Operations — Quarry Methods — Yard
Transportation — Manufacture of Roofing Slate — Storage of Roofing Slate —
The Art of Roofing with Slate — Manufacture of School Slates — Manufacture
of Mill Stock — Slate Floors, Walks, and Walls — Crushed and Pulverized
Slate Products — Waste in Quarrying and Manufacturing — Tests and
Specifications — Marketing — Imports and Exports — Tariff — Prices —
Bibliography

CHAPTER XI

SOAPSTONE 290

Composition and Properties — History — Uses — Origin and Occurrence —
Quarry Methods — Milling Processes — Marketing — Rocks Related to Soap-
stone — Bibliography

CHAPTER XII

Boulders as Building Materials 296

Origin and Nature of Boulders — Stone Fences — The Use of Boulders in
Buildings

CHAPTER XIII

Foreign Building and Ornamental Stones 301

Scope of Discussion — Imports of Stone — Foreign Limestones — Foreign

CONTENTS XI

Page
Sandstones — Foreign Granites — Foreign Marbles — Foreign Slates^ —
Bibliography

CHAPTER XIV

Miscellaneous Rocks and Minerals Used for Building and Ornamental

Purposes 342

Agalmatolite — Alabaster — Amazonite — Catlinite — Clay — Diatomite, Trip-
oli and Pumice — Fluorite — Jade — Labradorite — Lapis-lazuli — Malachite
and Azurite — Meerschaum — Mica Schist — Porphyry — Quartz — Snow and
Ice — Sodalite — Bibliography

CHAPTER XV

Deterioration, Preservation, and Cleaning of Stonework 348

Deterioration of Stone — Preservation of Stone — Cleaning Stone — Bibliog-
raphy

PART III
CRUSHED AND BROKEN STONE

CHAPTER XVI

General Features of the Crushed-stone Industries 371

History — Types and Values of Stone Used — Crushed Stone and Dimen-
sion Stone Contrasted — Uses of Crushed Stone — Competition — Markets —
Transportation — Prices — Royalties — Capital Required

CHAPTER XVII

Crushed and Broken Limestone 377

Types of Stone Included — Extent of Industry — Uses of Crushed and Broken
Limestone — Uses for Which Physical Properties Are Most Important — Uses
for Which Chemical Properties Are Most Important — Uses of Dolomite and
High-magnesian Limestone — Industry by States — Quarry Methods and
Equipment — Bibliography

CHAPTER XVIII

Crushed and Broken Stone Other Than Limestone 473

General Features — Uses — General Distribution and Value — Industries by
States — Quarry Methods and Equipment — Marketing — Bibliography

Index 493

INTRODUCTION

Stone, the foundation and superstructure of the everlasting hills,
is the most abundant of all material things. It is the earth itself on which
we live. Although widespread in occurrence to a point that breeds
contempt, stone is used so extensively that it touches the extremes of
human activity — from lowly shattered fragments trampled under foot
to flawless statuary marbles that provide material for the highest forms
of art. Between these two extremes stone and its products are essential
to multitudes of industries; they take part in the affairs of practically
every community and touch the life of nearly every person. To cover
in detail so broad a field would far exceed the scope of a single volume, but
an attempt is made to present a moderately comprehensive picture of the
properties and characteristics of stone, the methods of removing it from
its native beds and preparing it for use, its many applications in modern
industry, production centers at home and abroad, and the outstanding
economic features of each branch of this far-reaching industry.

Remarkable progress has been made in the quarrying and utilization
of stone. Its application to practical use was one of the oldest human
activities, extending far back before the earliest records, for the name
"stone age" is applied to that period of history of which knowledge is
conveyed to us only by crude tools and implements of stone fashioned
by the aborigines. Neolithic man, using a crooked reindeer antler as a
mining tool, dug flint balls from the chalk cliffs of England and shaped
them into spear heads or other implements. During later periods
American cliff-dwellers constructed crude homes with walls of stone.
The slow progress made through long ages from these primitive begin-
nings makes interesting chapters in ancient history but has little bearing
on the stone quarrying of today. Development of the industries in their
present scope has been comparatively recent. From caverns and shelter-
ing slabs of rock constituting the earliest human habitations to stately
mansions of cut and polished stone is a long journey, and every step of
progress has been marked by accelerated speed. Thus, although the
industries have existed for many centuries, the greatest advances in
manufacture and use have been crowded into the last fifty years. To
give a true picture of the status of these industries today is the purpose
of this book.

PART I
GENERAL FEATURES OF THE STONE INDUSTRIES

CHAPTER I
EXTENT AND SUBDIVISION

Extent of the Industry. — Stone production is the most widespread of
all industries in this country except agriculture, for rock deposits are
exploited in every State and in a great majority of the counties. In
the United States the average annual production of stone of all kinds,
including slate, from 1927 to 1931, was more than 176,500,000 short tons,
with an annual value exceeding $216,300,000. About 2,800 quarries and
mines are in operation, and the number of employees in them and in
directly associated plants is approximately 90,000.

Delivery of the enormous tonnage of stone to innumerable markets
is an important transportation item, involving rail, water, and truck
haulage. Coal and oil burned in quarries, mills, cement plants, and lime
kilns constitute an appreciable part of the fuel production of the country,
and the machinery and explosives used create an extensive market for
factory products. Thus, through its wide scope and complex ramifi-
cations stone holds a dominant place in the Nation's industry and exerts
a pronounced influence on national growth and development.

Major Divisions of the Industry. Dimension Stone. — The oldest use
of stone and the one that has become increasingly important through the
centuries is for building purposes. At first, rough walls were built of
scattered boulders, but with increasing knowledge of the use of tools
stone was quarried from solid ledges. Before the age of explosives and
before steam and compressed air were utilized quarrying was slow and
laborious; nevertheless, the pyramids and obelisks represent remarkable
engineering skill. These magnificent stone structures were built by
innumerable slaves, whose labor extended over many decades. Since
ancient times stone has been a favorite material for constructing the
finest buildings. Growth and development in art and architecture have
been expressed in noble structures, and we are indebted to the enduring
nature of stone for the preservation of many invaluable records of past
achievement.

The hewing of stone from its native beds with only the crudest hand
tools made it too costly for use, except in temples, palaces, and similar
structures. With the invention of explosives, the advent of steam power,
and, later, the use of electricity and compressed air, blocks of stone were
obtained with increasing ease, and rock became more and more widely
available as a building material. From cathedrals, bridges, and other

4 THE STONE INDUSTRIES

great public works it has found its way to smaller and less pretentious
structures, even to small one-family homes.

Dimension stone is used for other purposes than for building. In
ancient times a pile of stones was raised as a memorial, and from this
custom has developed the monument or headstone cut from suitable rock
and carved with a fitting inscription. Stone blocks are also used for pav-
ing streets and roads and for the manufacture of curbing. In addition,
stone has many special uses, such as for electrical switchboards and
blackboards.

Crushed Stone. — ^The use of crushed or broken stone developed much
later than that of dimension stone. Stone sledged by hand, usually by
convict labor, was used in road construction, and this use increased
rapidly. With the invention of cement and with mass production made
possible through explosives, power crushers, and screens the broken-stone
branch of the industry grew with phenomenal speed. In 1886 the output
of crushed and broken stone was smaller than that of dimension stone,
while in 1930 it was thirty times as great. Concrete aggregate, road
stone, and ballast are the principal products.

Stone Used in Manufacturing Processes. — For practically all the uses
mentioned above, stone is employed crude and untreated. It may be
shaped, polished, crushed, or ground, but its physical and chemical
properties remain essentially unchanged. In many modern industries,
however, stone undergoes physical and chemical changes, the final
product being quite different from the raw material in both form and
composition. Outstanding examples are limestones manufactured into
cement, lime, or calcium carbide; dolomite made into refractories; and
crushed sandstone fused with other products into glass.

Varieties of Stone Used. — The more common rocks used in com-
merce are granites and related igneous rocks, limestones, marbles, slates,
and sandstones. Soapstone also is included as a branch of the dimension-
stone industry. Many rocks in commercial use do not properly belong
to any of the foregoing groups. When employed as dimension stone
they usually are classed with one of the major groups; when used in
crushed or broken form they are considered a miscellaneous group.

CHAPTER II
MINERALS AND ROCKS

Distinction between Rock and Stone. — While the words "rock" and
"stone" are often regarded as synonyms, there is a definite distinction
in their meaning. The term "rock" is applied to a geologic formation
in its crude form as it exists in the earth. "Stone" is more properly
applied to individual blocks, masses, or fragments that have been broken
from their original massive ledges for application to commercial use.
Therefore, in chapter I the term "stone" is generally employed because
reference is made to manufactured products; in Chapter II "rock" is
used because the text relates to geologic formations as they exist in nature
before exploitation for economic use.

Relation of Rocks to Minerals. — To understand rocks properly one
should be acquainted with minerals, because rocks consist of them.
The relationship may be brought out most clearly by comparing minerals
with letters and rocks with words. Just as there is a word of one letter,
the article "a," so we have rocks made up essentially of a single mineral;
for example, limestone, which is the mineral calcite, or sandstone, a form
of quartz. Some words are made up of many letters, and in like manner
some rocks consist of several minerals; thus, granite consists of feldspar,
quartz, mica, and sometimes small quantities of hornblende, magnetite,
pyrite, garnet, and other minerals. A knowledge of rock-forming miner-
als is therefore a necessary preliminary to a well-balanced concept of
rocks. It may be mentioned, however, that some rocks consist wholly
or partly of natural glass or volcanic dust — materials that cannot properly
be classed as minerals.

Rock -forming Minerals. — It is assumed that the reader or student
who attempts to gain knowledge of the stone industries through these
pages has had at least an elementary course in mineralogy. Those who
lack this advantage or who desire to refresh their minds on the subject
are referred to textbooks or handbooks on mineralogy, because space will
not permit descriptions of minerals or means of their identification.

The important minerals in igneous rocks are feldspars, quartz, mica,
hornblende, and augite. Those most abundant in sedimentary rocks are
calcite, dolomite, and kaolinite (clay). Minor constituents include
chlorite, epidote, tremolite, actinolite, olivine, serpentine, garnet, sphene,
zircon, talc, pyrite, marcasite, magnetite, hematite, limonite, and
apatite.

6 ' THE STONE INDUSTRIES

Classification of Rocks. — Rocks are classified according to their origin
into three great groups — igneous, sedimentary, and metamorphic.
Igneous rocks are those that originated from molten masses or magmas
more recently regarded as high-temperature solutions. Semiliquid mag-
mas deep within the earth cool more or less slowly as they approach the
surface until a condition of solidification is attained. The nature of
the resulting rock depends on both the composition of the magma and the
rate of cooling. Magmas that cool very slowly at great depth tend to
form coarse-grained rocks, such as granites and gabbros, because slow
cooling ordinarily promotes coarse crystallization. On the other hand,
rapid-cooling magmas form fine-grained rocks, such as basalt and aplite.
Some rocks, consisting of relatively coarse crystals scattered throughout
a fine-grained ground mass, are known as the "porphyries."

Sedimentary rocks are sometimes referred to as "stratified," because
they are formed of sediments laid down in successive strata or layers.
The materials of which they are formed are derived from preexisting
rocks. Processes of rock decay or disintegration on the surface of the
earth, though very slow, are continuous and produce stupendous results
through centuries and geologic ages. Alternate frost and heat open
innumerable fractures in rocks; chemical agents of the atmosphere or of
surface and subterranean waters penetrate them and dissolve part of the
rocks. Rain, streams, waves, tides, and glaciers loosen the shattered
fragments, grind them up, and transport them far from their sources.
Wind, too, is an agent of erosion and transportation. . Millions of tons,
even cubic miles, of rock are disintegrated by these various agencies and
carried away to oceans, lakes, and river beds where they are deposited
as sediments. In addition to these products of rock decay, myriads of
organisms that inhabit the oceans or lakes secrete calcium carbonate or
silica from the water to form their shells, and their skeletal remains add
to the accumulations of rock-forming material. Thus, three great proc-
esses— rock disintegration, transportation, and redeposition — are now
and have been at work for ages. These processes — aided, as has been
stated, by organic agencies — have formed most of the sedimentary rocks.
Four major types are thus formed — conglomerate, sandstone, shale, and
limestone.

Metamorphism means change in form. Rocks of either igneous or
sedimentary origin that have been changed profoundly during the course
of their existence are known, therefore, as "metamorphic rocks." The
chief agencies that produce such changes are pressure, heat, and chemical
reaction. Rocks deep in the earth may become plastic under great pres-
sure and high temperature and by earth movement may be tilted or folded
into complex forms with a banded or schistose structure. Pressure may
cause recrystallization, and thermal waters may dissolve, transport, and
reprecipitate many minerals. Thus, new rocks may be formed of a

MINERALS AND ROCKS 7

texture and composition quite different from those of unaltered igneous
or sedimentary types.

The principal igneous rocks are granite, aplite, syenite, diorite, gabbro,
basalt, diabase, rhyolite, and tuff. Sandstone, conglomerate, shale,
limestone, and dolomite constitute the group of sedimentary rocks. The
metamorphic group includes gneiss, schist, quartzite, slate, marble, and
soapstone. Most of the above-named varieties are defined and described
in some detail in various following chapters devoted to discussion of their
distribution and exploitation. For those desiring a more thorough
treatise several textbooks on petrography are available.

General Distribution of Rocks in the United States. — As may be
inferred from the foregoing brief description of the origin of rocks, their
occurrence is directly related to the geologic history of each region.
The Appalachian district of eastern United States, extending from Maine
and Vermont to Georgia, is a rugged, mountainous region that has suffered
more or less extreme folding or metamorphism ; therefore, as one would
expect, metamorphic rocks, such as crystalline marbles, slates, gneisses,
and schists, are to be found there. Throughout the district many unal-
tered rock areas also occur and comprise important deposits of granite,
diabase, gabbro, sandstone, and limestone.

Between the Appalachian belt and the Rocky Mountains is a vast
area in which characteristic metamorphic rocks, such as marble, slate,
and gneiss, occur rarely because this is primarily a region of flat-lying
sediments that have been distorted very little by mountain-building
forces. Nearly horizontal limestone and sandstone beds are the charac-
teristic commercial rocks of the area comprising the eastern portions of
West Virginia, Kentucky, and Tennessee; all of Ohio, Indiana, Illinois,
Iowa, Nebraska, North and South Dakota, Kansas, Mississippi, Louisi-
ana, Florida, Oklahoma, southern Minnesota, Wisconsin, and Michigan;
and most of Missouri, Arkansas, and eastern Texas. Isolated areas of
granite occur in Wisconsin, Minnesota, Missouri, South Dakota, Arkan-
sas, Oklahoma, and eastern Texas.

West of the prairie country is another belt, the Rocky Mountain area,
in which the rocks are greatly crumpled and folded. Here again the
igneous and metamorphic rocks are abundant. This belt passes through
Idaho, Montana, Colorado, and New Mexico. Some of the granites,
gneisses, and marbles where accessible, have commercial importance.
From the Rocky Mountains to the Pacific Coast igneous rocks, of both
the granitic type and the more basic varieties such as basalt and gabbro,
are very common. Regional metamorphism has produced marbles and
slates, but many unaltered limestones and sandstones are found. Vul-
canism of comparatively recent geologic age characterizes much of this
great western area; and the resulting rocks, such as lava, rhyolite,
andesite, and volcanic tuff, are common. Such rocks are rarely found in
the Eastern or Central States.

CHAPTER III
FACTORS GOVERNING ROCK UTILIZATION

Rock Qualities on Which Use Depends. — Although rock is the most
abundant of all material things only a small fraction of the occurrences at
or near the earth's surface is fit for commerce. Requisite qualities which
are variable, depending upon the use to which the stone is to be applied,
are covered in following commodity chapters.

Importance of Other Factors Than Quality. — Although utilization
depends to a marked degree on physical or chemical adaptability, other
factors are equally important. Owners of rock deposits are prone to
assign too much importance to the quality of their materials without
adequate attention to certain economic factors that affect the success or
failure of any stone enterprise. For example, building-stone deposits of
most excellent quality would be valueless if situated in northern Alaska
because the cost of transportation to the nearest market would be
prohibitive.

Available Markets. — A study of market outlets for the type and
quality of stone available is essential to most successful operation. If the
quarry product is crushed stone or similar material that commands a low
price per ton, local markets are more important than those at a distance ;
favorable transportation, however, may extend the market range, which
is also influenced directly by production costs. A low-cost plant can
compete in a wider area than a high-cost plant handling the same class
of commodities. Present and probable future demand should be con-
sidered in relation to the production capacity of plants handling com-
petitive materials within the economic shipping radius. For relatively
high-priced products, such as ornamental granites and marbles, trans-
portation is a less formidable item in the total delivered price, and the
market range may be nationwide. A wide market area, however, brings
them into competition with all other similar materials ; successful market-
ing depends upon quality, workmanship, popularity with consumers,
prompt delivery, and aggressive salesmanship.

Diversification of Products. — Practically every quarry and pit can
produce a variety of grades and classes of materials, A slate quarry may
yield roofing slate, structural and electrical slate, blackboards, roofing
granules, and slate flour. A granite quarry may provide monumental
stone, cut stone, ashlar, rubble, paving blocks, curbing, and crushed stone.
Many operators tend to concentrate on one product and discard as waste

FACTORS GOVERNING ROCK UTILIZATION 9

any material that can not be applied to this particular use. For profitable
operation in a competitive market diversification of production is
desirable, and a market should be sought for all types of materials avail-
able in a quarry. Although a certain amount of waste is inevitable the
enormous piles of rejected stone in many quarry regions indicate that an
inquiry might profitably be conducted into the possibility of more
extended utilization of by-products.

Transportation Facilities. — Stone is heavy, and the haulage charge is a
considerable proportion of the delivered price; for the lower-priced
products it may be the chief item of cost at point of consumption.
Trucks now handle local delivery almost universally, and the cost
depends primarily on the nature of the roads. They are also being
employed to an ever-growing extent for distant delivery, the main
incentives being the increasing mileage of hard-surfaced roads and the
increasing speed of travel, as trucks carrying 6 to 8 tons now attain a
speed of 35 to 50 miles an hour.

For distant markets rail or water facilities are essential. Even
though the rock is of superior quality, deposits far from railroads may
have little value. Such markets are controlled largely by freight rates.
Wherever possible commodity rates should be established. Many
railroad companies prefer to haul stone because its imperishable nature
permits shipment in open cars.

Transportation by water is becoming increasingly important, as
indicated by the recent completion of a deep waterway on the Ohio River,
and the great increase in quantities of limestone, gypsum, and cement now
conveyed by this means. Attention may be directed to increasing
tonnages of limestone carried on the Great Lakes: 13,933,378 tons in
1927; 15,679,551 tons in 1928; and 16,269,612 tons in 1929. Water rates
are usually lower than rail rates.

Production Costs. — The success of any stone enterprise depends
largely on maintaining low production costs. High-cost plants can exist
in a competitive market only where some favorable circumstance, such as
superior quality of the stone, by-product utilization, effective sales
organization, or rapid delivery, gives them an advantage. Quarrymen
must therefore keep abreast of the times in efficiency of methods and
equipment. Today low cost depends primarily on plant mechanization.

Only by using some effective system of accounting can a knowledge
of costs be obtained. Hence systematized cost-keeping is to be regarded
as an important economic factor in conducting any stone enterprise.

Competitive Products. — Stone is meeting increasing competition
from metals and synthetic products. Aluminum is employed in place
of stone for both interior and exterior use. The movement toward all-
metal construction is attracting much attention, while glass, enameled
steel, and other ceramic products are finding new and important

10 THE STONE INDUSTRIES

uses. Alert stone producers are watching all such trends with exceeding
care.

Labor and Wages. — Usually the largest single item in production cost
is the amount paid in wages. Abundance or scarcity of labor, the
prevailing wage level, and living conditions have an important influence
on quarry methods. Scarcity of labor or abnormally high wages encour-
age more complete mechanization. Most stone producers recognize the
value of giving special attention to the health, safety, and comfort of their
workers, for by so doing they build up a personnel of steady employees, a
condition advantageous to both employer and laborer.

CHAPTER IV

PROSPECTING AND DEVELOPMENT
PROSPECTING

Development work should not be started on a deposit without
reasonable assurance of an available mass of rock sufficiently high in
quality and abundant in supply for profitable exploitation. Prospecting
is often found advantageous in quarries that have long been in operation ;
it is, in fact, a continuous activity with some companies, which enables
them to determine the extent of reserves and to plan future developments
intelligently.

If the rock appears in bare outcrop, usually a rough estimate of its
quality and extent can readily be made. Sedimentary rocks are, as a rule,
fairly constant in composition throughout the same bed or zone of
deposition, and the greatest variations are found in passing from one bed
to another; therefore, all beds that may be included in a quarry are
usually sampled. A cliff or escarpment along a stream or gulley is
especially valuable, because it provides a cross section which permits
tests of quality at various levels. If such a cross section is not available
in nature, test holes are drilled at such intervals as will supply adequate
data on the whole area under consideration.

The prospecting method is governed to some extent by the type of
operation. If the chemical composition of the rock is of primary impor-
tance, as in furnace flux, lime, or cement materials, churn-drill cuttings
will supply material for chemical analyses. Drill cuttings are sampled
at regular intervals, for example, every 5 feet, and an exact record is kept
of the drill hole and depth at which each sample is taken. The distance
between samples is governed by the uniformity of the rock. Where
analyses lack uniformity samples are taken at closely spaced points while
in rock of more constant composition they are obtained at wider intervals.

For dimension-stone and most crushed-stone uses the physical are
more important than the chemical properties of a rock. Dimension stone
must be free from cracks, of uniform texture, of attractive color, and for
some uses capable of taking a polish. For crushed-stone uses rock must
have satisfactory strength, soundness and low absorption. Churn-drill
samples can not be used for testing these qualities. Core drilling is
desirable because it not only provides data on the structure and extent
of the deposit, but this type of drill cuts out cylindrical masses suitable
for making physical tests. Diamond core drills which are in common

12 THE STONE INDUSTRIES

use, consist of a rotating steel drum with black diamonds (carbonados)
set in its lower edge. Some of the newer types of extremely hard alloys
are now being used as substitutes for diamonds in cutting softer rocks.
Shot drills also give satisfactory service; cutting is done with a rotating
steel drum fed with steel shot as an abrasive. Prospect-drill cores are
usually 3 inches, or smaller, in diameter.

The position and spacing of holes are governed by the nature of the
rock. Usually the geology of a region is studied thoroughly. General
information regarding the geology usually may be obtained from Federal
or State geological reports, although some companies employ trained
geologists to work out the structure and relationships of all rock forma-
tions associated with an operating or prospective quarry.

No definite rules can be given for the position or arrangement of holes.
In flat-lying beds of uniform thickness and fairly constant composition
they may be spaced at wide intervals — 100, 500, or 1,000 feet; where
rocks are folded or tilted, or where changes in composition or structure
occur within short distances, they should be spaced more closely.
Detailed maps are made for complex deposits. From a map constructed
after careful study of exposures the position, thickness, and slope of beds
may be determined with fair accuracy. In bedded deposits drill holes
usually are projected approximately at right angles to the bedding. To
intersect steeply dipping beds inclined drill holes may be required; for this
purpose a core drill has advantages over a churn drill, for it may be used
to drill holes at any angle, even in a horizontal position if so desired, while
except in rare instances churn-drill holes are vertical.

Accurate records of every drill hole are kept, and a map is made
showing its exact location. As each core section is removed it is marked,
recorded, and stored for future reference. Some large companies main-
tain fireproof storage sheds for prospect-drill cores.

The direct cost of sinking 5}^- to 6-inch churn-drill holes in limestone
is 20 to 60 cents a foot. These figures apply to constant drilling by
experienced workmen. Drilling harder rocks, such as trap rock and
granite, is more expensive, the cost ranging from $1.50 to $6.00 a foot.
Core drilling with shot or diamond drills costs $3.00 to $5.00 a foot,
depending on the nature of the rock and drilling conditions.

When the extent of a stone deposit is known, the approximate ton-
nage may easily be determined. Rocks vary somewhat in weight.
Merrill^ compiled tables of the weight of many building stones. The
average of 68 granites was 166 pounds per cubic foot; of 36 limestones,
dolomites, and marbles, 161 pounds; of 76 sandstones, 141 pounds;
and of 4 trap rocks, 182 pounds. Sandstones are the most variable
because they differ so much in porosity.

1 Merrill, G. P., Stones for Building and Decoration. 3d ed., John Wiley &
Sons, Inc., New York, 1910, pp. 498-507.

PROSPECTING AND DEVELOPMENT 13

To determine the approximate number of short tons available in a
limestone deposit the length, width, and depth in feet, as proved by-
prospect drilling or other methods, may be multiplied and this product
is then multiplied by the average weight per cubic foot (161 pounds)
and divided by 2,000. For granite or sandstone the corresponding figure
for weight per cubic foot may be substituted. Generally it is deemed
unwise to expend the large sum necessary to establish quarries and finish-
ing plants unless as a result of prospecting a reserve of good rock suflficient
for at least 20 years' operation is assured. Some companies operating
dimension-stone deposits open up quarries at moderate expense and sell
their products in rough blocks until the quality of the rock is proved,
marketability established, and a definite income assured. In due time
finishing mills may be built and equipped.

The determination of overburden is a phase of prospecting. Both
the depth and nature of overlying material, whether sand, gravel, clay,
or inferior rock, may be learned by drilling or trenching.

STRIPPING

Nature and Thickness of Overburden. — Stripping is the process of
removing the overburden of clay, gravel, or sand from the rock surface.
Many deposits of marketable rock are overlain with inferior quality rock,
which in a sense may be regarded as overburden. However, as methods
of removing solid rock, whether barren or useful, are quite distinct from
those employed in handling soil, removal of inferior waste rock is to be
classed as a quarrying rather than a stripping problem.

Most stone producers are interested in stripping. In certain places
quarries are worked in rock formations that appear in bare outcrop, and
fortunate owners of such quarries may view their neighbor's stripping
problems with a certain degree of complacence. Most commercial
rock deposits, however, are covered with varying depths of rock debris.
Indeed, the absence of all overburden is not always an unmixed blessing.
The writer has observed granite areas where 10 feet or more of soil has
preserved the rock almost to the surface, while other parts of the area
that were in bare outcrop were altered and discolored too greatly for
monumental use to depths of 4 to 8 feet. Removal of such rock as waste
is moreover more costly than removing several feet of soil.

The depth of overburden ranges from a few inches to 10, 20, 30, and
in exceptional instances even 40 or 50 feet. Likewise, the nature of mate-
rials composing it is variable. It may be easily disintegrated loam,
sticky plastic clay, sand, gravel, boulders, or even a hardpan that may
require blasting.

Stripping usually is a problem of greater magnitude in the crushed
than in dimension-stone industries. For crushed-stone uses a great
volume of stone must be handled; many quarries produce thousands of

14 THE STONE INDUSTRIES

tons a day. This great bulk of material demands rapid widening of
quarry walls, and stripping may become continuous. The dimension-
stone branches of the industry handle relatively higher-priced products
per ton which require much more labor in preparation, and the tonnage
produced is correspondingly lower. Working at much greater depths is
justified by the more valuable products, and 5 or 10 years may elapse
before a new pit is started or a new bench opened.

Clean Stripping. — For certain classes of quarries clean stripping is
essential; for others it is immaterial. Purity has first importance for
stone applied to chemical uses. Silica and alumina are most undesirable
impurities in limestone for lime manufacture and for furnace flux, and
such impurities are the chief constituents of the overburden. Clean
stripping is therefore essential at such quarries. On the other hand, in
the manufacture of portland cement clay is added to the limestone to
obtain a proper mixture; hence, if some clay is quarried with the rock
and proper care exercised in subsequent addition of clay, no detriment
to the product will ensue. Similarly, in dimension-stone production
surface debris will not harm the product ; it will be separated from quarry
blocks in due course and removed with other quarry waste. In best
quarry practice, however, as much of the overburden as can be handled
conveniently is removed before underlying rock is quarried.

Stripping Difficulties Due to Erosion Cavities. — Limestone and marble
are exceptionally difficult to strip because the slow erosion of circulating
water follows joints and cracks and thus wears away the rock surface
very irregularly, leaving numerous tortuous cavities filled with clay,
sand, or gravel. Generally the upper 10 or 20 feet consists of knobs or
pinnacles of rock standing in a mass of clay. Granites, sandstones, and
trap rocks are also subject to erosion, and quite irregular surfaces may
result; usually, however, they are comparatively smooth and regular.
Erosion cavities cause much difficulty and greatly increase the cost of
stripping.

Stripping Methods. — No quarry process is more variable than strip-
ping. The nature and depth of overburden and conditions of its removal
and disposal show wide differences from quarry to quarry. Therefore,
equipment and methods commonly employed are subject to similar
variations, which are discussed briefly in the following paragraphs.

Hydraulic Method.— The hydraulic method, which simply involves
washing the overburden away with a stream of water under pressure, is
the cheapest and most effective. Conditions for its successful use are,
however, somewhat exacting, the chief requirements being as follows:

1. An ample supply of water must be obtainable. An average of
about 10 tons of water is needed for each ton of overburden removed.
However, the same water may be used repeatedly if settling basins are
provided for clarification.

PROSPECTING AND DEVELOPMENT

2. A favorably situated waste-disposal area is essential. The best
conditions exist where the soil may be washed back from the quarry face
or laterally into ravines or basins where it may remain.

3. Hydraulicing is effective only where the overburden is friable
enough to be washed down and carried away with a stream of water.
The presence of hardpan or of numerous heavy boulders may cause great
difficulty and justify the use of other methods.

The equipment required for hydraulic stripping includes a pump, a
pipe line, a mounted nozzle or monitor, and possibly an additional
dredging pump, together with the necessary source of power. A great
advantage of the hydraulic method is the wide range of action and ease of
moving from one point to another. Its adaptability for removing clay
and sand from irregularly eroded surfaces is an outstanding advantage.

1 I . 1 A rugged ruck builaet stripped b> the hj draulic method.

Soil that could be removed only with great difficulty by other means is
washed out by the stream of water directed into pockets and cavities.
This means is therefore particularly adaptable for stripping limestone or
marble deposits. Figure 1 shows a typical eroded limestone surface
from which practically all soil has been washed away by this method.

Hydraulic stripping is a potent source of stream turbidity which may
be detrimental to other interests. This drawback may be overcome by
establishing wide settling basins.

The cost of hydraulic stripping is quite variable but usually very low.
Costs range from less than 1 cent to 12 cents a cubic yard in quarries in
different parts of the country.

Dragline Scraper or Excavator. — Where a convenient dumping ground
is available a dragline scraper is effective. It lacks flexibility in lateral
movement, however, unless provided with special attachments; if worked

16 THE STONE INDUSTRIES

from a derrick arm it is much more flexible, as the entire equipment is on a
portable mounting, and the lateral motion of the derrick arm gives the
excavator a wide range of action. Draglines have been used successfully
in cleaning out large erosion cavities filled with clay.

Power Shovel. — The power shovel is the most popular type of stripping
equipment. Steam and electric shovels are in common use, and com-
pressed-air shovels are employed in a few localities. Power shovels
handle material of all kinds with great facility but are not well-adapted
for work on uneven rock surfaces. For removing clay from the larger
erosion cavities some of the smaller types of tractor or caterpillar shovels
with dippers not more than three-fourths yard in size are used. Various
methods have been tested to overcome successfully the difficulty of
stripping rough, eroded limestone surfaces with a power shovel. As
they are encountered rock projections may be broken by blasting and
set to one side or thrown over the edge of a quarry by means of the shovel
dipper; better access to the soil is thus provided. Another method is to
blast and load rock and soil together, but unless a washer is used clean
separation later is difficult.

Costs of power-shovel stripping vary greatly according to conditions.
A thick overburden of easily excavated soil on a smooth rock surface may
be loaded and removed to a near-by dump for only 15 to 30 cents per
cubic yard. Under average conditions the cost runs from 30 to 50 cents
a cubic yard, but where loading is difficult it may be considerably higher.

Other Mechanical Equipment. — For cleaning out deep erosion cavities
clamshell buckets worked from derrick arms have limited application.
Small tractor excavators similar to those for road grading are also
employed. Where the overburden is moved only a short distance
mechanical conveyors are used. Scrapers with or without wheels, hauled
by horses or mules, are employed where the overburden is too thin for
successful power-shovel operation. Various methods may be combined,
as, for example, a dragline scraper which dumps through a trap in a
platform into cars that are hauled by locomotives.

Hand Methods. — Removal of overburden by hand methods, involving
the use of picks and shovels by quarry workers, is slow and laborious.
Under modern wage conditions it is also costly. Dirt loading by hand at
quarry floors is often done by contract at 15 to 25 cents a cubic yard,
but the dirt is loose and easily loaded. Loosening and loading undis-
turbed soil may cost 30 to 45 cents a cubic yard, and a haulage charge
must also be added. Clay dug from deep pits and cavities by hand may
require several handlings and the cost is increased proportionally.

Utilization of Overburden. — At some cement-plant quarries clay
which overlies the limestone may be one of the necessary raw materials;
otherwise, it is rarely used except as a filling material. In the latter
capacity it may be employed to fill swamps, ravines, or other low places.

PROSPECTING AND DEVELOPMENT 17

rendering such areas available for agriculture or building. Overburden
may also be used for dams, roadways, or railroad grading. In rare
instances clay overburden is suitable for brick.

Disposal of Overburden. — Proper disposal of material stripped from
rock surfaces requires keen judgment and foresight. Desire to attain
quick results at small expense and lack of foresight regarding probable
extent of future operations are the chief causes of removing soil to an
insufficient distance from the excavation, a common mistake in stripping.
In quarrying dimension stone a large amount of waste usually is added
to the pile of overburden, and in the course of years the accumulation
may be very extensive. Consequently, after a few years' operation
quarry owners find it necessary to handle waste a second time, augment-
ing greatly the expense of quarrying. If excavations are too close to
spoil banks, as quarries are gradually enlarged rock slides may result;
some quarries have been abandoned on this account.

As important as distance is the direction in which waste is carried.
If prospecting has been adequate the direction future development must
take usually can be determined. Thus, if workable beds are narrow and
steeply inclined, obviously lateral development must follow the direction
of strike; nevertheless, in many quarry regions waste has been piled
directly over good rock that would in the natural course of events be
quarried in a few years. Thus, extension of workings is impeded or
made more costly.

Provision for adequate disposal of waste is therefore an important
part of every quarry plan. It may, indeed, be found necessary to carry
waste a considerable distance, in which event an efficient transportation
system is essential. Overburden and waste are at times thrown into
abandoned quarries, but before this is done an operator should be assured
that permanent abandonment is fully justified.

Avoidance of Stripping by Underground Mining. — By adopting under-
ground mining methods the stripping problem is sometimes effectively
solved. An unusually heavy overburden is one of the chief incentives for
undertaking excavation of rock by means of drifts and tunnels, for this
method eliminates stripping costs.

GENERAL METHODS OF OPERATION

Open-pit Quarrying. — Most rock products of commerce are obtained
from open quarries. Material suitable for use ordinarily is found at or
near the surface of the earth, and the most economical method of working
is to open up a face of the rock ledge. As rock is separated by blasting or
other means, an opening is gradually enlarged and deepened, its size and
shape depending greatly on the rock structures. Wide, shallow openings
may be made in comparatively thin flat-lying beds, such as are common
in limestone districts of the Middle West. Where beds are folded and

18 THE STONE INDUSTRIES

tilted at high angles, as in the Appalachian region of the Eastern States,
open pits may be narrow and deep. Some open-pit slate quarries of
Pennsylvania have reached depths of 500 to 700 feet because the desirable
beds are relatively narrow and almost vertical. Also, where land values
are high, and property lines restricted, or where a heavy overburden of
soil or waste rock makes lateral extension expensive, quarries are likely
to be narrow and deep.

There are two types of quarries, the "shelf" quarry and the "pit"
quarry. Sometimes a ledge of serviceable rock stands above the level
of the surrounding country, and by working into the hillside a quarry
can be developed, with the floor little if any lower than the surrounding
land surface. Such ready access and easy transportation are advan-
tageous. Furthermore, drainage is usually automatic, and pumping
expense is avoided. Excavations of the shelf-quarry type can usually be
classed as low-cost operations.

Conditions are not always so favorable; a rock deposit may not
extend above the general level, and a pit must be sunk. Access is gained
by ladders, stairs, or mechanical hoists, and material is transported from
the quarry by inclined tracks, derricks, cableway hoists, or other means.
Such pit quarries also require pumping. Though less advantageous than
shelf quarries, thousands are in regular operation. When properly
designed and well-equipped they may be operated at a cost which
compares favorably with that at many shelf quarries.

Underground Mining. — When quarrying of rock first was begun as an
industry, excavations were made in formations readily available at the
surface of the earth. Through long years of continued operation the
most available outcrops were gradually worked away, and quarries
reached increasing depths. Many limestone beds which provide suitable
stone dip at steep angles and are of limited thickness. In following these
beds down the dip greatly increasing depths of overburden are encoun-
tered. Consequently, in many localities mounting difficulties in the
way of open-pit quarrying, with rising costs, have induced operators to
change their systems of excavating and to develop underground mining
methods. Many limestone and marble, and a few granite and slate
deposits, are successfully mined underground. Selective mining can best
be accomplished by the underground method, for drifts and tunnels
may be confined to serviceable rock, waste and overburden being left
undisturbed. As workmen are not exposed to the weather, working
conditions are also more favorable.

Gloryhole Mining. — Gloryhole mining is adapted only to the produc-
tion of broken stone. This method has features in common with both
open-pit and underground mining, and is modified to suit varying condi-
tions. A circular or oblong open pit is the most usual type. Rock
is quarried around the sides and conveyed by dragline or other means

PROSPECTING AND DEVELOPMENT 19

to a funnel-shaped opening at the center, where a chute is provided
through which the rock is conducted to cars which convey it to the
surface through a tunnel.

Bibliography

The following bibliography contains references to a few important articles that
have appeared during recent years on prospecting and stripping.
Armstrong, W. D. Hydraulic Removal of Overburden from a Stone Quarry.

Cement, Mill, and Quarry, vol. 27, no. 2, 1925, p. 35.
Bowles, OLrvER. Stripping Methods at Pits and Quarries. Pit and Quarry, vol. 8,

no. 3, 1923, p. 108.

Stripping Clay from Seams and Pockets in the Shenandoah Valley of

Virginia. Rock Products, vol. 26, no. 5, 1923, p. 53.

Stripping a Stone Quarry. Cement, Mill, and Quarry, vol. 33, no. 3, 1928,

pp. 6-14.
Engineering and Mining Journal. Finding New Mines. Vol. 116, 1923, p. 573.

Selling a prospect. Vol. 123, 1927, p. 2.

Hauer, D. J. Developing a Quarry. Pit and Quarry, vol. 9, no. 1, 1924, p. 61.
Massey, G. B. Hydraulic Stripping. Pit and Quarry, vol. 10, no. 10, 1925, p. 77.
MiLKowsKi, V. J. Hydraulic Stripping of Quarry Overburden. Rock Products,

vol. 26, no. 5, 1923, p. 51.
Pit and Quarry. Top Soil Removed by Two Clever Excavating Schemes. Vol. 8,

no. 5, 1924, p. 112.

Hydraulic Stripping of Overburden. Vol. 12, no. 3, 1926, p. 85.

When to Strip Overburden. Vol. 12, no. 11, 1926, p. 93.

Hydraulic Stripping in the Indiana Limestone District. Vol. 14, no. 10,

1927, p. 77.

Rock Products. Round-Table Discussion of Quarry Operation; Quarry Stripping.

Vol. 27, no. 5, 1924, p. 78.
Rush, D. B. Exploration and Geological Examination of a Quarry Property and

Their Relation to Financing. Rock Products, vol. 27, no. 5, 1924, p. 56.
Stone, R. W. What State Geological Surveys Are Doing for Rock Products, Rock

Products, vol. 27, no. 4, 1924, p. 27.

PART II
DIMENSION STONE

CHAPTER V

GENERAL FEATURES OF DIMENSION -STONE INDUSTRIES

DEFINITION OF DIMENSION STONE

The term ''dimension stone" is generally applied to masses of stone
prepared for use in the form of blocks of specified shapes and usually of
specified sizes. Other forms that find commercial use are designated
"broken," "crushed," or "pulverized" stone. Stone fragments that
are classed in the second group may be of specified sizes, the sizing usually
being accomplished by screening, but the outstanding distinction between
fragments of broken or crushed stone and masses of dimension stone is
that the former are irregular and are in an infinite variety of forms,
while the latter are cut to definite shapes such as rectangular, columnar,
tabular, or wedge-shaped.

PRINCIPAL USES

Building Stone. — One of the chief uses of dimension stone is as a
material of construction, but this branch of the industry contains many
subdivisions. In its broader sense the term "building stone" includes
stone in any form that constitutes a part of a structure; however, cut or
rough-hewn blocks for exterior w^alls are most widely used. They may
be employed only for certain parts, as for window sills, trim, cornice,
base courses, chimneys, or steps.

Cut stone is employed extensively for both interior and exterior
columns. The more ornamental types are utilized for interiors,
as floor tiles, steps, wainscoting, fireplaces, hearths, mantels, baseboards,
banisters, toilet inclosures, laundry tubs, and in various other ways.
Slabs are used for flagging. Cut stone is also in demand for bridges,
dams, retaining walls, docks, sea walls, lighthouses, and similar structures
where strength, permanence, and resistance to shock are essential.

Building stone used in the construction of walls is of four main types —
cut or finished stone, ashlar, rough building stone, and rubble. Cut
or finished stone is the most costly because, for the most part, blocks
are accurately shaped in accordance with detailed drawings. They
may be plain rectangular blocks for uninterrupted walls or cut and
carved to special shapes and designs for corners, window and door
spaces, caps, or cornices. This classification includes sawed limestone
and marble, finished or semifinished.

THE STONE INDUSTRIES

"Ashlar" is a term applied in general to small rectangular blocks
of stone having sawed, planed, or rock-face surfaces, contrasted with
cut blocks which are accurately sized and surface-tooled. Many types
are in use. Even-course ashlar consists of blocks of uniform height for
each course, although succeeding courses may be of thicker or thinner
blocks. They may be of uniform or of random length. Exceptionally,
end joints are slanting or irregular. Random ashlar consists of blocks

Fig. 2. — Ashlar in two-unit heights.

^ n ^^-

■Ar

Fig. 3.

-A common method of laying ashlar in three-unit heights.
Limestone Company.)

(Courtesy of Indiana

of several sizes that may be fitted together to make a wall having irregular
and unequally spaced joints. Two, three, or more unit heights may be
employed, as several smaller sizes may give the same height as one of the
larger blocks. Thus, as shown in figure 2, the two smaller blocks with a
mortar space between reach the same height as the larger block. In
figure 3 the use of random ashlar in three-unit heights is shown. It
may be observed from this figure that blocks which fit together properly
with 3^^-inch motor joints must have thicknesses of 4, 8)^, and 13 inches,
respectively. Random ashlar not only provides builders with means
of attaining remarkable variety in architectural design but permits
quarry and mill operators to utilize fragments of various sizes that

GENERAL FEATURES OF DIMENSION-STONE INDUSTRIES 25

might otherwise be wasted. The building of random ashlar walls is
mason's work, while the setting of cut stone is a separate art.
^ Rough building stone consists of rock-faced masses of various shapes
and sizes. Stone masons build them into walls having irregular joints.
They are widely used in residential construction for chimneys, basements,
or entire walls, and also to some extent for public buildings, bridges,
fences, and the more ornamental types of retaining walls.

Rubble is the crudest form of building stone. The term is generally
applied to irregular fragments having one good face. Such rock was once
in ordinary use for basement walls, retaining walls, or similar types
of construction for which concrete is now generally employed. Produc-
tion of rubble has declined greatly during recent years.

Monumental Stone. — Memorials range from simple markers and
headstones to elaborate and massive monuments. Usually stone that
takes a good polish is requisite; in fact, the very highest types of flawless,
uniform stone are used for monumental purposes. However, monuments
with tooled, hammered, or even rough-hewn surfaces are not unusual,
and less flawless stone may be thus employed.

No sharp line can be drawn between monumental and building stone,
for monuments merge into buildings. The Washington Monument is
essentially a building equipped with an elevator for passenger service,
though in design and purpose it is a monument. The Lincoln Memorial,
the Arlington Amphitheater, the Bok Singing Tower, and mausoleums in
various parts of the country are other memorials that have many features
of buildings and for which building stone is used.

Paving Stone. — One of the early uses of stone was for street and high-
way paving, the old Roman roads of Britain being outstanding examples.
While the demands for hard-surfaced roads were not so urgent long ago as
today, there was real need for something better than dirt or even broken-
stone roadways, particularly for the heavy traffic of growing cities.
Concrete was unknown, and blocks of native stone were the logical
materials. "Cobblestones" — rounded or irregular blocks — were widely
used but were gradually replaced by rectangular paving blocks with
smooth, even surfaces. During recent years concrete and macadam have
far outstripped paving blocks for hard-surfaced road construction, but
many stone pavements still give unsurpassed service under the most
severe traffic demands. They are found chiefly in railroad freight yards,
around docks, and in streets traversed by many heavy drays and trucks.
Paving blocks are also much in use between street-car tracks, not only
because of their wearing qualities but because of the facility with which
they may be taken up and replaced when track repairs are necessary.

Although the softer types of paving stones are gradually disappearing
with heavy traffic increasing year by year, granite and indurated sand-
stone, the most resistant types, are still in wide and steady demand.

26 THE STONE INDUSTRIES

Curbing. — The manufacture of curbing is an important branch of the
stone industry. Curbstones are of two types — straight and corner.
Corner curbs are curved; they are more difficult to make than straight
curbstones and require more material, as a considerable amount of rock
is wasted in shaping them. The harder stones are more durable than
concrete and on this account are particularly well-adapted for corner
curbs where shocks from the wheels of traffic are exceptionally destructive.

Flagging. — Flagging is used chiefly for sidewalks and for paving
courts, landings, and platforms, but the advantages of concrete for such
uses have led to a rapid decline in output. In the past probably 95 per
cent of the total flagstones produced were of bluestone, a variety of
sandstone. Ornamental slate flagging is now used quite extensively
and limestone, granite, and trap rock to a limited extent.

Miscellaneous Uses. — Stone is utilized in a multitude of minor ways
that may not be included in any of the above groups. In household
equipment it is found as radiator covers, table and dresser tops, lamp
bases, vats, sinks, refrigerator shelves, and flour bins. Ornamental
types are used for novelties, such as ink w^ells, paper weights, smoking
sets, ash trays, clocks, and statuary. Slate is used for blackboards,
bulletin boards, and billiard-table tops. Several types of stone are
widely used for electrical panels and switchboards. In yards, gardens,
and parks stone is employed for walks, stepping stones, statuary, foun-
tains, bird baths, and garden seats.

REQUISITE QUALITIES OF DIMENSION STONE

General Requirements. — Although innumerable occurrences of rock
are to be found throughout the world only a small part of them consist of
rock that will satisfy the exacting requirements of dimension stone.
Freedom from cracks and lines of weakness is essential. No deposit
that has irregular or closely spaced joints is suitable, because sound
blocks of moderate to large size are demanded. Uniform texture and
grain size, together with a constant and attractive color, are usually
required. The rock must also be free from minerals that may cause
deterioration or staining.

Another important quality is the state of aggregation. If the grains
are loosely coherent the rock may be described as "earthy" or "friable."
Rock in which the grains adhere closely and strongly is the most desirable.
However, when cementation is carried to an extreme as in the case of
some quartzites, the rock is very difficult and expensive to work. Some
important qualities that demand consideration are discussed in the
following paragraphs.

Composition. — A rock consists of one or more minerals made up of
elements combined in definite proportions, which may be determined by
chemical analysis, and the minerals may be determined by visual observa-

GENERAL FEATURES OF DIMENSION-STONE INDUSTRIES 27

tion with the unaided eye or with the assistance of a hand lens or micro-
scope. Often the value of a chemical analysis of dimension stone is
overemphasized, as adaptation to use depends chiefly on physical
properties. At times an analysis may have value; for example, it may
indicate the amount of clay in a limestone, a fact which has some bearing
on its durability. Usually study with a petrographic microscope is
much more effective than chemical investigation; it is also quicker and
cheaper. One skilled in the use of a microscope may identify the minerals
in a rock and note their state of aggregation, freshness, relative abundance,
impurities, and texture and to some extent interpret the history of the
rock and learn what influences have been at work to improve or impair
it for structural or other uses.

Hardness and Workability. — The hardness of a rock is its resistance
to abrasion and depends directly on the hardness and texture of its
component minerals. Most of the constituents of granite are as hard as
or harder than steel, and such rock is therefore difficult to tool. Pure
limestones are soft enough to be scratched easily with a knife. Marbles
are somewhat harder than limestones. The grains of a sandstone consist
of quartz, which is very hard, but workability depends rather on the
nature of the cementing material and its state of aggregation. A friable
sandstone may be worked readily because the grains separate with ease,
while a siliceous sandstone or quartzite, in which they are firmly cemented
together with quartz, is very difficult to cut and dress.

Hardness has direct bearing on the workability of all rocks, yet its
effect on use is quite variable. For exterior or interior walls or for
decorative effects the hardness of a rock is unimportant, in so far as
quality is concerned, because it is not subjected to wear. On the other
hand, for floor tile or stair treads hardness is very important, as the rock
is subjected to severe abrasion. It is the most essential quality of stone
used for paving and curbing, for such stone must be able to resist
adequately the abrasive action of heavy traffic.

Texture. — The term "texture" as applied to rock means size, degree of
uniformity, and arrangement of its constituent mineral grains. In the
rougher types of building stone uniformity is not required; in fact, recent
architectural demands tend toward variable, uneven texture. In the
more ornamental types of building and monumental stone uniform
texture has vital importance.

Qolor. — Rocks are of many colors, and choice depends on individual
taste or "prevailing fashion. Choice of color in stone is influenced by
location. For smoky cities white and very light colors are undesirable.
Some rocks change in color with age, but this is not always objection-
able. Practically all colors are in demand for monumental stone,
and those rocks in which there is marked contrast between polished and
tooled surfaces are preferred, for on such monuments inscriptions are

28 THE STONE INDUSTRIES

most easily read. For building stone, red, brown, buff, gray, or white
rocks are widely employed. Dark-gray or black rocks are in demand
only for certain special uses. The buff or yellow tints of many limestones
and sandstones and the red or pink coloration of many granites are due
to the presence of minute grains of iron oxides, but these are stable minerals
that cause no stains. Surface stains are serious blemishes and are
generally due to the presence of small grains of pyrite, marcasite, or
siderite which oxidize by weathering. Stains sometimes are caused by
cementing materials used in setting the stone.

Strength. — Rock is a very strong material. Structural stone that is
sound and suitable in other respects is almost invariably strong enough
for any use. Bridge piers, arches, and the bases of tall monuments must
sustain great pressure, but even in such structures the strength of ordinary
stone far exceeds the requirements of safety. The pressure on the base
course of the Washington Monument is less than 700 pounds a square
inch; and high-grade granites, limestones, and marbles will sustain a
crushing load of 10,000 to 25,000 pounds a square inch. Recent tests
at the United States Bureau of Standards on samples of Montana
quartzite indicated the remarkably high compressive strength of 63,000
pounds a square inch. A structure of such material would have to be
over 10 miles high before failure would occur from crushing of the lower
courses. It is, however, generally conceded that rock disintegrates and
tends to weaken more readily when under severe stress ; therefore a factor
of safety of 20 is usually demanded — that is, stone must be able to resist a
crushing stress twenty times as great as that to which it will be subjected
when placed in a wall. For ordinary uses, a stone that will sustain a
crushing strength of 5,000 pounds to the square inch is considered
satisfactory.

Tests of transverse strength — strength required to sustain a load
applied at the middle of a bar of stone supported at the ends — are more
important than crushing-strength tests, for they show the adaptabil-
ity of the stone for use as window and door caps.

Porosity. — Pore space or porosity, expressed as the percentage of pore
space to the total rock volume, is quite variable in different types of rock.
Sandstones may have a porosity of 1 to 10 per cent. Commercial
limestones range from less than 0.5 to 5 per cent. Marbles, granites,
and slates are usually of very low porosity, many of them less than one-
tenth of 1 per cent. Porosity affects the durability of stone by permitting
infiltration of water which may contain solvents, or which may freeze in
the pores. Early writers have stated that danger from frost action is
directly proportional to the percentage of pore space, but Buckley^ has
pointed out that the important factor to consider is the facility with which

^ Buckley, E. R., The Building and Ornamental Stones of Wisconsin. Wisconsin
Geol. and Nat. Hist. Survey Bull. 4, Econ. Ser. 2, 1898, p. 22.

GENERAL FEATURES OF DIMENSION-STONE INDUSTRIES 29

the stone gives up water. Rocks having pores of subcapillary size give
up their included water much more slowly than those with larger pores,
therefore those with fine pores suffer most seriously from frost action.
Parks^ determined the permeability of many rocks and found that it
bore no relation to the percentage of porosity or to the effect of frost.
It is apparent, however, that the solvent effect will be greater in rocks of
greater permeability. The extent to which a stone will take up water is
usually expressed as ratio of absorption, which is the proportion of the
weight of absorbed water to the weight of the dry sample.

Specific Gravity and Weight per Cubic Foot. — The specific gravity
of a stone is its weight compared with the weight of an equal volume of
water. It may be expressed in two ways — as "apparent" or as "true"
specific gravity. Apparent specific gravity is that obtained when pore
spaces are filled with air throughout the determination. True specific
gravity is obtained when pore spaces are eliminated, either by so com-
pletely saturating the rock that they are filled with water or by using
finely ground rock powder in making the determination.

The specific gravity of common rocks ranges from 2.2 to 2.8 and the
weight per cubic foot from 140 to 180 pounds, depending upon the weight
and relative abundance of the constituent minerals and upon the porosity.

Data on Physical Properties. — Merrill* presents numerous tables
showing specific gravity, strength, weight per cubic foot, ratio of absorp-
tion, chemical composition, and other properties of many building stones.
Since that book was written many thousands of tests have been made
and the results recorded. The United States Bureau of Standards has
made the most noteworthy contributions to our knowledge of the physical
properties of building stones. Publications^ covering marbles, lime-
stones, and slates are now available. Dale's various reports on marble,
granite, and slate as recorded in the bibliographies of the respective
chapters in this volume, also contain a great deal of physical test data.
Numerous textbooks and State reports also present tables or incidental
information on crushing and transverse strength, ratio of absorption,
weight, and other physical properties of stones from innumerable specific
localities. A compilation of this great mass of data would constitute

^. Parks, W. A., Report on the Building and Ornamental Stones of Canada. Can-
ada Dept. Mines, vol. 1, pt. 1, 1912, p. 62.

* Merrill, G. P., Stones for Building and Decoration. 3d ed., John Wiley & Sons,
Inc., New York, 1910, pp. 497-579.

^ Kessler, D. W., Physical and Chemical Tests on the Commercial Marbles of the
United States. U. S. Bur. of Standards Tech. Paper 123, 1919, 54 pp.

Kessler, D. W. and Sligh, W. H., Physical Properties of the Principal Commercial
Limestones Used for Building Construction in the United States. U. S. Bur. of
Standards Tech. Paper 349, 1927, 94 pp.

Kessler, D. W., Physical Properties and Weathering Characteristics of Slate.
U. S. Bur. of Standards Research Paper 447, 1932, 35 pp.

30 THE STONE INDUSTRIES

a book in itself, and lack of space forbids its presentation herein. There-
fore, the reader who desires knowledge of the qualities of stones from,
certain locations is referred to the texts mentioned in the footnotes or
given in the appropriate bibliographies.

Durability. — Climate has a very definite bearing on the durability
of stone. Cleopatra's Needle, a column of granite which was transported
to New York and set up in Central Park, is said to have suffered more
from exposure during a score of winters in the climate of America than
during the centuries it stood in the mild, uniform climate of Egypt.
Probably incipient decay had begun before its removal, and the severe
climate of this country speedily made the deterioration apparent.

Most standard commercial types of building and ornamental stones
are sufficiently durable for ordinary use. By examining the effects of
weathering on outcrops that have long been exposed to the elements in
undeveloped deposits the durability of rock may be judged, or where
stone has been quarried for many years observations may be made on
old structures in which it was used. In this respect America does not
have the advantages of the Old World, for even our oldest buildings are
comparatively new when considered on the basis of the life of high-grade
stone.

Durability of stone is now tested quite extensively in laboratories,
chiefly by means of accelerated freezing and thawing tests and by accel-
erated acid tests. Resistance to fire is an important consideration. It
has been found that limestones withstand the effects of fire up to the
point of calcination better than other stones. Next in order are sand-
stones, fine-grained crystalline rocks, and the coarser crystalline rocks.
As a rule, the finer grained and more compact the stone and the simpler
its mineral composition the better it will resist damaging effects of
extreme heat or the spalling effects that result from rapid cooling when
water is applied.

More detailed requirements for specific uses will be included under
the discussion of each commodity.

ADAPTATIONS OF RAW MATERIAL TO USE

Stone is employed in many different ways. Obviously the require-
ments of use are variable. Stone products differ from synthetic com-
pounds in that the composition and properties of the latter can within
certain limits be changed at will, whereas the composition and physical
character of stone remain exactly the same in the finished material as in
the solid rock ledge. Man can fashion rock into any desired size or shape
and can polish or otherwise finish the surface, but he is powerless to
change in the slightest degree the texture, inherent color, hardness, or
proportion or character of constituent minerals. He has, however, the
power of selection, and this must be exercised with great care. The

GENERAL FEATURES OF DIMENSION-STONE INDUSTRIES 31

stoneworker must study his material, be familiar with its properties,
and understand the requirements of use. He is thus enabled to judge
the possibilities of a rock deposit and its adaptations. Some rocks
are eminently fitted for monumental uses, some for building, and others
for interior decoration.

COMPLEXITIES IN MARKETING

Some quarrymen simplify their marketing problems by selling prod-
ucts in rough-block form to dealers or manufacturers. Rough blocks,
however, command a much lower price than finished products, and the
desire for larger incomes and increased profits has led many operators
to establish mills of their own. If structural stone is manufactured
marketing may become complex. Some quarries specialize in one
product, the marketing of which may be simple. While, as previously
shown, diversification has its advantages, marketing becomes more
complex because the various products may enter entirely different fields
of utilization. Large quantities of granite, limestone, and sandstone
are sold as rough blocks to independent mills, but slate is usually manu-
factured in plants directly associated with quarries.

ROYALTIES

Stone deposits are sometimes owned by one individual or company
and operated by an independent concern. Such properties are usually
worked on a royalty basis. Factors to be considered for the most
reasonable determination of royalty are the value of the deposit and the
quantity of commercially available material therein. Thus a fair market
value for the property, divided by the number of tons or number of
cubic feet of rock available, will give a fair figure for royalty.

The value of rock in the ground is commonly overestimated, for it
really constitutes only a small part of the selling price of the finished
product. A fair market value is often difficult to determine. It may be
defined as the value agreed upon between a willing seller and a prudent
purchaser, both of whom have enlightened understanding of the com-
modity involved.

Royalty is commonly expressed as a percentage of the selling price
at the mine or quarry. According to the Leasing Act of June 30, 1919, as
amended December 16, 1926, a minimum royalty of 5 per cent of the
net value of the output at the mine is charged for minerals taken from
Government lands. The royalty may exceed 5 per cent, the exact figure
being determined from a review of all the circumstances surrounding
each individual commodity or deposit.

Whatever the basis of determination, royalty is usually charged as
so much a ton or cubic foot of material sold. Royalties vary considerably
depending upon size of operation, value of product, and other factors. In

32 THE STONE INDUSTRIES

the Atlanta (Ga.) district, a royalty of 25 cents a cubic foot of block
granite and 2 to 5 cents a cubic foot of granite curbing is customary.
For Indiana limestone sold as cut stone, commanding a price of $2 or S3
a cubic foot, royalties ordinarily range from 4 to 10 cents a cubic foot.
If the limestone is sold as rough building stone the royalty is lower and
may be 2 to 5 cents a cubic foot. Royalties on slate are commonly about
10 per cent of the net selling price. A minimum average daily or monthly
production is usually a condition of a royalty agreement.

CHAPTER VI

LIMESTONE

DEFINITION

Limestone is a rock consisting essentially of calcium carbonate
(CaCOs), the mineral calcite. Rocks classed commercially as limestones
may contain varying quantities of magnesium carbonate; when 10 per
cent or more is present they are termed "magnesian" or "dolomitic"
limestones; if the amount approaches 45 per cent the rock is composed
essentially of the double carbonate of lime and magnesia (CaCOs,
MgCOs), the mineral dolomite. When used as dimension stone dolomite
is classed commercially as limestone.

ORIGIN

As pointed out in a preceding discussion of sedimentary rocks,
limestones have originated chiefly from calcareous organic remains,
supplemented to some extent by chemical precipitation. Only those
limestones that have been firmly consolidated have importance as
dimension stone.

PHYSICAL PROPERTIES

Limestones vary greatly in physical characteristics. Hardness
depends on the degree of consolidation as well as on the actual hardness
of the component minerals, but even the densest forms of limestone can
be easily scratched with a knife. They range from pure white to black,
the color effects being brought about chiefly by impurities. In texture
they may be amorphous, semicrystalline, or crystalline. They vary in
compactness from loosely consolidated marls through the denser chalks
to compact normal limestones and the harder marbles. The less-compact
limestones have the higher degree of porosity and may weigh as little as
110 pounds per cubic foot, whereas the more compact varieties may
weigh 150 to 170 pounds. For most uses dense, highly consolidated
forms are preferred.

VARIETIES

Limestones are classified according to the nature of their impurities.
"Siliceous" or "cherty" limestone contains considerable silica and
"argillaceous" limestone clay or shale. The so-called "cement rock,"
which is widely used for cement manufacture in the Lehigh Valley district
of Pennsylvania, is a good example of the latter. A "ferruginous"

34 THE STONE INDUSTRIES

limestone contains iron, which usually gives rock a buff, reddish, or
yellowish color; the "carbonaceous" or "bituminous" type contains
carbonaceous matter, such as peat or other organic materials.

Another series of names is applied to limestones, according to their
texture, state of aggregation, or appearance. "Common compact"
limestone, the most widespread type, consists of a fine-grained, dense,
homogeneous aggregate ranging from light gray to almost black. "Lith-
ographic" limestone is an extremely fine-grained, uniform, crystalline,
magnesian variety, usually drab or yellowish. As its surface can be
etched with weak acid, it may be employed for lithographic printing.
"Oolitic" limestone, so-called because of its resemblance to fish roe, is
composed of small rounded grains of lime carbonate of concentrically
laminated structure. When the grains approach the size of a pea the
rock is called "pisolite."

Limestone is composed primarily of shells of ancient sea animals.
Usually they have been comminuted so completely that no trace of
organic structure remains. Some beds, however, have been formed under
conditions that have left the shells almost intact or at least in fragments
well preserved enough to indicate their character and origin; these are
known as "fossiliferous" limestones. Some are made up almost entirely
of shells of one kind and are named accordingly. "Coral," "crinoid,"
and "coquina" are common types. "Chalk" is a fine-grained, white,
friable limestone composed largely of minute shells of foraminifera. In
places, oyster-shell beds are quite extensive in area and thickness and
are more or less firmly consolidated; therefore, they may be regarded as
shell limestones of very recent origin.

"Travertine" is a variety of limestone that is regarded as a product
of chemical precipitation from hot springs. As it is deposited in suc-
cessive layers and as chemical composition and conditions of deposition
may vary during this process, a banded structure commonly results. The
rock is characterized by the presence of numerous irregular cavities
ranging from the size of a pin's head or smaller to one-half inch or more
across. Some porous limestones are classed commercially as travertines,
though they differ from them in origin. Some travertines will take a
fair polish, but most of them are used with a sand-rubbed finish and
therefore are classed as limestones rather than marbles. Travertine
is used principally for interior walls, decorative effects, floor tile, and
steps. Some varieties are remarkably resistant to wear. Use as a
flooring material in the concourse of the Grand Central Station in New
York is a good illustration of the adaptability of travertine for service
where abrasion is constant and intense. Artificial travertines — syn-
thetic products — are sold as substitutes, but they have neither the wearing
nor the decorative qualities of true travertine, "Tufa" is a name applied
to a cellular calcareous deposit originating from mineral springs.

LIMESTONE 35

Another form of calcium carbonate is precipitated from cold-water
solutions in limestone caves and forms many ornate structures, such as
stalactites and stalagmites. It is incorrectly called "onyx," although
the more descriptive term "Mexican onyx" or "onyx marble" is often
applied to distinguish it from true onyx, a form of silica. As Mexican
onyx will take a polish and is highly ornamental it is classed with marble
rather than with limestone.

QUALITIES ON WHICH USE DEPENDS

Although innumerable deposits of limestone are to be found through-
out the country, only a small part of the rock will satisfy the exacting
requirements of dimension stone. Sound rock, free from deleterious"^
impurities and providing blocks of adequate size, is essential. Uni-
formity of texture, grain size, and color is usually required.

Purity is not regarded as an essential property of building limestone,
but chemical composition may have some bearing on quality. Silica
may make the stone more difficult to work. The appearance of sulphur
in an analysis usually indicates the presence of pyrite or marcasite,
minerals that may cause stains. Objectionable impurities are recognized
generally more easily by means of a microscope or a hand lens than by a
chemical analysis. Waste-stone by-products from relatively pure
deposits are more easily marketed than impure by-products.

Hardness and workability are important qualities. Limestones are
worked with comparative ease unless flint or other siliceous minerals are
present. Hardness has a direct bearing on the workability of limestone,
but its effect on use has minor importance, because limestones are used
where they are subjected to abrasion only to a limited extent.

Limestones are of many colors. Brown, buff, gray, or white varieties
are widely employed for building purposes, while the dark-gray or black
are in demand only for certain uses. Buff or yellow coloring is due to
minute grains of iron oxides — stable minerals that cause no stains. Sur-
face stains may result from oxidation of the iron sulphides or carbonates
sometimes present.

Sound structural limestone which is suitable in other respects is
usually strong enough for any use. Even for bridge piers, arches, and
tall monuments the strength of standard high-quality limestone far
exceeds the requirements of safety.

Pore space is variable; in most commercial limestone it ranges from
less than 0.5 to 5 per cent, though occasionally is much higher.

Appearance depends chiefly on color and texture. Blue limestones
may change to buff by oxidation of the iron. Generally, however,
permanence of color is preferred. Although uniform texture is usually
desired for the more ornamental stones, variations in both texture and

THE STONE INDUSTRIES

color are now much in demand for sawed and rock-faced stone used in
domestic construction.

USES

Limestone in the form of dimension stone is used principally in build-
ing. Its very limited application for monuments, curbing, and flagging
may almost be disregarded. The largest amount is employed in the form
of cut or rough-hewn blocks for exterior walls, either for entire structures
or for certain parts, such as window sills, caps, cornice, or base course.
Columns and balusters of the more ornamental types are widely utilized
for both interior and exterior building. Limestone is also employed
extensively for interior structural uses and decorative effects. Massive
blocks of cut limestone are used for bridges, dams, docks, sea walls, and
similar structures where strength, permanence, and resistance to shock
are essential.

Limestone for the construction of walls is of four main types — cut
or finished stone, ashlar, rough building stone, and rubble. The signifi-
cance of these terms is fully covered in a discussion of the general features
of dimension stone on pages 23 to 25. Limestone is being used increasingly
as ashlar, rough building stone, and rubble. The denser, harder varieties
are used for street curbing and to a smaller extent for flagging and
paving.

Production of dimension limestone by uses for a series of years is
shown in the following table:

Dimension Limestone Sold by Producers in the United States, 1925-1937,

BY Uses

Year

Building stone

Curbing, flagging,
and paving

Rubble

Total value

Cubic feet

Value

Cubic
feet

Value

Short
tons

Value

1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937

15,983,800

18,537,950

17,340,690

17,641,370

17,864,700

15,682,720

11,706,840

7,414,130

6,599,250

5,176,860

6,871,320

7,735,520

7,736,140

$16,092,079

20,391,597

18,820,045

20,193,963

20,649,257

18,535,293

10,858,697

7,028,224

6,416,223

3,391,455

2,700,747

4,662,716

5,096,535

129,730
167,780
223,370
322,560
471,880
346,040
166,260
122,000

78,610
116,610

93 , 700
178,000
167,950

$ 98,587

135,882

134,360

205,724

158,266

137,801

85,176

38,332

32,134

49,886

44 , 229

74,053

76,806

324,630
254,240
226,280
365,920
352,480
756,470
229,510
84 , 570
79,060
190,080
185,790
204,700
107,650

$513,387
476,545
400,790
705,723
693 , 678
623,100
296,426
84,308
94,046
179,791
276,569
181,415
136,028

$16,704,053

21,004,024

19,356,195

21,106,410

21,501,201

19,296,194

11,240,298

7,150,864

6,642,403

3,621,132

3,021,645

4,918,184

. 6,309,369

LIMESTONE 37

INDUSTRY BY STATES

Limestones occur in every State; but, except in widely scattered
localities in about one-half of the States, they are either unsuitable for
use, or conditions have been unfavorable for their development as sources
of dimension stone. The more important producing centers are briefly
described alphabetically by States in the following section. No attempt
is made to cover undeveloped deposits or to include all that are or have
been worked on a small scale.

Alabama. — The Bangor oolitic limestone of Palaeozoic age occurs in
Franklin County, northwestern Alabama. The deposit extends from
Newberg to Belgreen, about 20 miles, and has an average thickness of 20
to 25 feet, though it is much thicker in places. The best occurrences are
near Rockwood and Russellville. The rock is a characteristic oolitic
limestone similar to the extensive deposits near Bedford, Ind. Most of it
is of uniform texture, though some is distinctly veined. It grades in color
from light- and medium-gray to buff and is somewhat harder than
Indiana limestone. Many quarry openings have been made, and since
1924 production has increased notably. Recent developments are
chiefly near Rockwood, where a large stone-finishing mill is in operation.
Here quarrying is conducted with the most modern equipment, and the mill
is provided with all conveniences for rapid and skillful fabrication. The
easy workability of the stone gives the product a wide market range;
large contracts have been filled, even for cities as far north as Montreal,
Canada. The technique of quarrying and manufacture is covered in a
later section of this chapter, for while most of the discussion on this sub-
ject applies to Indiana, much of it will apply equally to Alabama.

Colorado. — A sandy limestone of Cambrian age, occurring near
Manitou, El Paso County, is marketed under the trade name "Manitou
Green-Stone." The body color is reddish brown, on which is imposed an
attractive green mottling. Calcium and magnesium carbonates con-
stitute about half the rock, the remainder consisting chiefly of quartz,
with a minor percentage of iron oxide. The green color is attributed to
the presence of glauconite or a related mineral. Quarry conditions are
favorable, as the rock occurs in easily separable beds having a maximum
thickness of about 2 feet. Tests by the Colorado Geological Survey
indicate that it is strong and durable. Active development of this very
attractive building stone began in 1930. Colorado travertine is discussed
on page 44.

Florida. — The coquina or shell limestone of Florida is probably the
first building stone used in America. It consists of stratified shell
fragments cemented together with finely divided calcium carbonate
derived from abrasion and comminution of the shells, and it is soft enough
to be cut easily with a handsaw. Although too porous for exterior use in

38 THE STONE INDUSTRIES

northern climates it appears to be quite enduring in the Florida climate.
Experiments are being conducted in search of a practical method of
hardening the stone and reducing its porosity to make it suitable for use
in climates subject to severe frost action.

It occurs in a belt about 200 yards wide on Anastasia Island and
was first quarried about 1580 to supply blocks of stone for building at
St. Augustine the famous Fort San Marco (the present Fort Marion),
which required many years for its construction. Though soft and porous
the fort walls were remarkably resistant to gun fire. St. Augustine is
called "the coquina city," because so much of this material has been used
for buildings. There has been little recent production in this district, but
a similar coquina limestone is quarried near Volusia, Volusia County. At
Islamorada on Windly's Island, Monroe County, a considerable quantity
of limestone is quarried and sold as cut and sawed stone and as flagging.
The Tampa limestone, occurring at New Port Richey, Pinellas County, is
quarried to some extent for building purposes. In places it is porous, like
travertine, and is said to be very pure, containing about 98 per cent of
calcium carbonate.

A soft limestone deposit at Marianna, Jackson County, in northern
Florida is known locally as "chimney rock." Many years ago it was
quarried in a small way and sawed into slabs when first taken from the
ledge. The blocks or slabs became quite hard after seasoning and were
used for making chimneys, house supports, or entire houses.

Florida travertine is referred to on page 44.

Illinois. — At times building limestone is quarried near Quincy, Adams
County; at Alton, Madison County; and at Joliet, Will County. In the
last locality the rock occurs in flat-lying homogeneous beds 6 to 30 inches
thick. It is a fine-grained, light-drab stone which upon exposure becomes
buff by oxidation of the small iron content. Large blocks are obtainable.
Production in the State is small, and practically all of it is for rough
construction.

Indiana. — Indiana limestone, also called Bedford limestone, Bedford
oolitic limestone, and Indiana oolite, is one of the most widely known
building stones. Figures compiled from returns of individual companies
to the United States Bureau of Mines show that, exclusive of a small
amount of stone sold for rough construction, data for which are not
available, and also exclusive of rubble, Indiana in 1930 produced 12,702,-
980 cubic feet of dimension limestone valued at $16,186,172, or more than
81 per cent of the total quantity and 87 per cent of the total value for the
United States. Corresponding figures for 1931 were 7,874,470 cubic feet
valued at $8,595,612, and for 1937, 4,442,360 cubic feet valued at $3,529,-
420. More than twenty large companies operate thirty to forty quarries
and mills. About a dozen more operate only finishing mills. The value
of finished products from independent mills is not included in the total

LIMESTONE 39

value. Its easy workability, adaptability for carving, attractive appear-
ance, endurance, and abundant supply have given to Indiana limestone
nationwide popularity. Chief production is in the Bedford-Bloomington
district in Lawrence and Monroe Counties, but building limestone is also
quarried at St. Paul, Decatur County, and at Romona, Owen County.

Structural Features. — Bedford oolitic limestone, known geologically as
the Salem limestone, is of Subcarboniferous (lower Carboniferous) age.
It rests on the Harrodsburg limestone and is overlain by the Mitchell
limestone. All the formations are tilted gently a little south of west,
with a dip of 34 to 70 feet per mile. Thus, in following the formations
westward they are found at gradually increasing depths beneath the
surface. In the eastern part of the area quarries are on the hilltops ; in the
west part, in the valleys.

The Salem limestone occurs in a massive bed 25 to nearly 100 feet
thick. In Indiana it extends from near New Albany on the Ohio River
northward through Salem, Bedford, and Bloomington to a point north of
Greencastle, a distance of about 125 miles. Active quarrying is confined
chiefly to the central part of the belt, from Bedford at the south to a few
miles beyond Bloomington at the north.

The rock has little tendency to split along bedding planes. Its
freedom from cleavage is a great advantage in carving, as corners and
projections are not liable to split off. Cross-bedding occurs in places.
Joints generally appear in two systems, the major having a general east
and west direction, with minor joints north and south. As joints are
spaced 20 to 40 feet apart in most places large, sound blocks are easily
obtained.

The rock is remarkably free from ordinary bedding or lamination
planes; however, unusual types known as "suture joints," "crowfoot,"
"toe nails," or "stylolites" occur in many places. They appear on the
quarry face as dark-gray to black jagged lines in zones a fraction of an
inch to several inches wide. The dark material is mainly organic matter
or chlorite, and the peculiar zigzag form is attributed to differential
solution under pressure. Some of the thicker stylolites tend to weather
rapidly at the exposed face but are not generally detrimental to quality
or strength. "Crowfoot" rock, sold under the classification "Old
Gothic," is preferred for certain architectural effects.

Bedford stone is described as oolitic because of its resemblance to fish
roe. The small, spherical grains or oolites are regarded as having orig-
inated from chemical precipitation of calcium carbonate in sea water.
Usually small grains of sand or shell fragments form nuclei of the spherical
masses, and, if crystalline, the calcium carbonate deposited about them
may be radial or concentric. True oolites are not so numerous in Indiana
stone as one would expect from the name, as most of the grains are simply
shell fragments of foraminifera or other marine animals. What is known

40 THE STONE INDUSTRIES

as select stone is fine-grained (less than 3'^4 inch in diameter), though
medium-grained (3-^4 to 3^^ inch) and coarse-grained (more than 3=-^ inch)
are also popular.

A "rift," or direction of easy splitting, is present in most Indiana
quarries. In places it is horizontal but more generally is inclined north
or south at a low angle and probably is due to crossbedding.

Color. — Indiana limestone is divided into two general color classifica-
tions, buff and gray. The buff color is regarded as a result of slow
oxidation of the small iron content, because the gray to bluish-gray stone
is generally found below ground-water level and the buff above. It is a
curious fact, however, that uniform gradation from blue to buff is rarely
seen; the boundary is usually sharp and distinct. The buff stone appears
in various shades, which in general are divided into dark and light buff.
Variegated rock is a mixture of buff and gray in the same block, though
weathering processes gradually blend the colors until little or no differ-
ence is observable. Variegated stone is preferred for the contrasted
color effects desired in modern architecture.

Hardness and Workability. — When first quarried Indiana limestone is
comparatively soft and is easily worked but when thoroughly dried it is
somewhat harder. Consisting as it does of an aggregation of rounded
grains, it has certain working qualities that are among its most admirable
characteristics. It can be readily planed, turned, or carved into any
desired form and is therefore well adapted for any type of architectural
design. It can be tooled so rapidly that it has an advantage in cost of
manufacture over almost all other stones.

Durability. — The statement is sometimes made that, because it is
slowly soluble in water containing carbon dioxide gas, limestone is not to
be classed with the durable rocks. Loughlin^ has pointed out, however,
that carbon dioxide gas, even in a humid atmosphere, has no corrosive
effect on limestone and that when dissolved in water it exerts a solvent
action so slow that under ordinary weathering conditions it would require
450 years for this solution alone to corrode the surface two-fifths of an
inch. Limestone, therefore, may be regarded as durable enough for all
ordinary uses.

Generally the heavier stone is the more durable because it is more
firmly cemented and less porous than varieties that are comparatively
light in weight. Weight per cubic foot may therefore be regarded as an
index of its durabihty. The average specific gravity is 2.3, and the
average weight per cubic foot about 144 pounds.

Most standard building limestones are unaffected by frost after
they are properly seasoned, but unseasoned stone is subject to damage;

*Loughlin, G. F., Indiana Oolitic Limestone; Relation of Its Natural Features to
Its Commercial Grading. Contributions to Economic Geology, 1929, pt. 1, U. S.
Geol. Survey Bull. 811, 1929, p. 113.

LIMESTONE 41

therefore quarry blocks should be exposed, with access of air to all
surfaces, for 1 to 2 months before heavy frost. Quarrying is discontinued
during the winter because of the damage that would result from the
freezing of freshly quarried stone.

Grades of Stone. — Loughlin,^ working in cooperation with Indiana
producers, has devised the following classification :

Buff; AA, statuary; unusually fine, uniform grained. A, select; fine, uniform
grained. B, standard; prevailingly medium grained with rather distinct bedding.
C, rustic; prevailing coarse grained. Gray; D, E, EE, correspond to grades
A, B, and C of buff stone. Variegated (buff and gray in a single block): F,
variegated statuary, corresponding to AA; G, variegated, corresponding to B
and C. Special grades: Hard, "Indiana travertine," very coarse grained with
many large shell holes; "old Gothic," or stone of any color or grade, with or
without "crowfeet" or other features that would exclude it from regular grades;
"short length" stone equal in quahty to the regular grades but in blocks smaller
than those usually sent to stone mills.

A limited supply of rock classed as Indiana travertine is available.
Although fine-grained stone is desirable, too rigid insistence on this
grade would work a hardship on the industry, as it would cause excessive
waste of other grades that must be quarried at the same time, neces-
sitating a higher price and automatically limiting the market range.
The coarser grained stone is equally as good as the fine; consequently
the grading is not excessively rigid, and a moderate tolerance is allowed.

Extent of Supply. — The occurrences of Salem limestone are very
extensive, but quarrying is necessarily confined to a zone near the
outcrop as the removal of more than 40 to 60 feet of overburden would be
unprofitable. Even in this comparatively narrow zone the supply of
rock will be abundant for many years. Naturally the supply of buff
stone is more limited than that of blue-gray. Although certain local
areas may be nearly exhausted, new deposits are constantly being
uncovered.

Prospecting in Indiana. — As the quality of stone varies from point to
point, careful prospecting is necessary before development work can be
undertaken. The essential features, such as color, grain size, and extent
of beds, can be determined from drill cores. Because the beds are almost
flat lying and changes in texture and color are gradual, prospect holes
may be spaced 100 to 300 feet apart, although some operators prefer
closer spacing. A log of the thickness, color, and texture of the limestone
found in each drill hole is kept.

Kansas. — A light-cream limestone has been quarried quite exten-
sively near Silverdale, Cowley County and white limestone suitable for
cutstone trim near Manhattan, Riley County. Other production in the
State is chiefly for local rough construction.

^ Work cited, p. 114.

42 THE STONE INDUSTRIES

Kentucky. — The most widely known building stone of Kentucky
is the oolitic limestone of Warren County quarried near Bowling Green.
The rock is similar to Indiana limestone in color, texture, composition,
and durability. It occurs in sound beds 10 to 20 feet thick ; and, although
it is notably uniform in composition, care must be taken in selection to
avoid small pyrite lenses that may cause stains on exposure to the
weather. A peculiar feature is the presence of bituminous matter which
gives the freshly quarried stone a displeasing coloration, but which
evaporates rapidly upon exposure, leaving a clean cream-white to
light-gray surface. Quite a number of quarries have been worked at
various times, but only two companies have produced building stone
during recent years. Rough blocks are shipped to Bowling Green for
manufacture into finished products. The stone has been used in many
large buildings throughout the Middle Western and Southern States
and is employed to some extent for monuments.

Maryland. — Dolomite quarried near Mount Washington at the
northern edge of Baltimore is used at times for rough construction in and
near the city. A deposit of attractive gray limestone near Texas,
Baltimore County, is also quarried for building purposes.

Minnesota. — Dolomitic limestones ranging from nearly pure white
to yellow or buff, occur in flat-lying beds in southeastern Minnesota.
Certain beds, notably at Mankato, are blue when first quarried but
turn buff on exposure, probably from oxidation of the iron originally
present as carbonate.

The chief producing centers are Mankato, Blue Earth County;
Kasota, Le Sueur County; Mantorville, Dodge County; and Winona,
Winona County. The stone at Mankato and Kasota is strong, attrac-
tive, and obtainable in large blocks; it is well-adapted for construction of
heavy masonry and bridges. The chief commercial beds at Kasota are
recrystallized to such an extent that the material will take a polish and
is therefore sometimes classed as marble rather than limestone. Yellow
and pink Kasota stones are popular for interior decoration. A gray to
white attractive and durable building stone is obtained high on the
river bluffs near Winona. In some ledges the stone is porous and is
marketed as travertine.

Missouri. — Stone quarried at Carthage and Phoenix is classed as
marble and is described in the marble chapter.

New York. — Limestones for building, both dressed stone and rubble,
are quarried near Syracuse, Onondaga County. A small amount is
produced elsewhere, chiefly for local rough construction.

Pennsylvania. — There are many important deposits of limestone in
Pennsylvania, but they are used very little for building purposes. Beds
that should furnish the best building stone are situated in the south-
eastern part of the State where geological forces have folded and shattered

LIMESTONE 43

them excessively. Cambrian and Ordovician limestones of Northamp-
ton, Lehigh, and Berks Counties were used for foundations and house
building many years ago. The rock is available only in small blocks
but apparently is quite durable. The date 1821 appears in the gable
of a limestone house about 4 miles north of Easton, Pa., and the building
apparently is still in excellent condition. Limestones of Cumberland,
Franklin, and Montgomery Counties have been used locally for dwellings
and arched bridges. Local limestone was used in the construction in
1766 of the Harris Mansion, the oldest house in Harrisburg, and also
for the Paxtang Church just east of that place built in 1740. Pennsyl-
vania limestones evidently have an interesting history, but they are
used very little at present. Limestones now produced in Pennsylvania
are classed chiefly as rough construction stone, and the annual value of
the output is S25,000 to $100,000.

Texas. — Texas limestone quarrying has exhibited increasing activity
during recent years. At Cedar Park, Williamson County, a ledge about
30 feet thick provides a pale-buff to cream oolitic limestone of even
texture, well adapted for carving. Certain beds contain large fossils and
are porous, resembling travertine. Large shipments of building stone
are made from these quarries.

At Lueders, Jones County, a deposit of thin-bedded, light-gray and
variegated limestone covering a wide area has been quarried quite
extensively. Three beds — 8 inches, 1 foot 5 inches, and 1 foot 10 inches
thick, respectively — are separated by loose beds about 2 inches thick.
Therefore, no channeling machines are required, as the rock is easily
removed by drilling and wedging.

Near Del Rio, Kinney County, a 15- to 30-foot ledge in layers 2 to 4
feet thick has been quarried over an area of 5 or 6 acres. The stone is
harder and less uniform than that quarried at Cedar Park.

Utah. — A fine-grained, light-colored, oolitic limestone is quarried near
Ephraim, San Pete County, and used as building stone in Salt Lake City
and Provo. Some has been shipped to San Francisco.

Wisconsin. — Limestone of Niagara age is quarried at Wauwatosa,
Mihvaukee County. It is light gray, with variations to white and buff.
Two types are procured, a finely crystalline compact limestone and one of
coarse granular texture in heavy beds. The chief market is in Milwaukee,
where the stone has been used for bridges, ashlar, footings, sills, and rubble.

A thin-bedded, hard, gray dolomite, exceptionally strong and durable,
occurring near Lannon, Waukesha County, has been used quite exten-
sively for curbing and flagging ; some is employed also as building stone.

OCCURRENCES OF TRAVERTINE

Travertine has not been produced extensively in the United States,
although sales have been recorded from a few States during recent years.

44 THE STONE INDUSTRIES

Some porous limestones sold commercially under this classification are
not true travertines.

A quarry near Bridgeport, Mono County, Calif., which, many years
ago, furnished what was regarded as marble for buildings in San Francisco,
was again operated in 1929. The stone comes in a variety of colors;
some of it, ranging from clear white to pale yellow and gray, is said to be
of the same texture and quality as the best Roman travertine. It is also
obtainable in orange, pink, red, and brown.

A deposit that compares favorably with the famous Italian travertine
has been developed about 6 miles east of Salida, Colo., close to the
Denver & Rio Grande Western Railway. The deposit forms one side of a
hill rising 250 feet from the valley floor and is worked as a shelf quarry
conveniently situated for waste disposal and with automatic drainage.
The exposure is 1,300 feet long and 200 feet thick. Joints are spaced so
widely that blocks large enough for monolithic columns are obtainable.
The rock is said to have a compressive strength of 12,000 to 14,000 pounds
a square inch and on account of its porosity weighs only 135 pounds a
cubic foot. It is light buff, is very attractive, and is being used widely in
Denver and other cities for both interior and exterior building.

Two other travertine quarries have been opened recently in Colorado,
one near Salida, Chaffee County, and one near Canon City, Fremont
County. Up to 1931 production was confined to terrazzo.

In 1932 production of travertine was begun at Gardiner, Mont., near
the north entrance to Yellowstone National Park. As the material occurs
in a variety of ornamental colors and is adapted for polishing, possibly
it should be classed as onyx marble. Several carloads have been shipped
to St. Paul, Minn., for sawing and finishing. Travertine also occurs west
of Landusky, Phillips County, Mont.

A deposit of rock well-adapted for architectural use has been worked
near Bradenton, Fla. The stone exhibits the characteristic porous
texture of Italian travertine and resembles it in general appearance.
Production has been recorded since 1929, some of the material being
sold under the trade name "Floridene" stone.

A travertine quarry was operated for a brief period near Cuthbert,
southwestern Georgia. The rock is brown to golden and of porous
structure. Limited amounts were sold for interior building and waste
material was marketed as chips for terrazzo floors.

The output of certain porous beds in the limestone bluffs near
Winona, Minn., is sold as travertine, though most of the limestone in this
district is massive and compact. Similarly, exceptional beds resembling
travertine occur in the Indiana limestone deposits, but very little is
marketed. An attractive porous limestone is quarried near Cedar Park,
Tex.

LIMESTONE 45

QUARRY METHODS

Quarry Plan. — Most deposits of limestone used as dimension stone
are approximately flat lying and of limited thickness. Thus, the stone
available in any one opening may be removed within a short time and a
new ledge uncovered. The abandoned pits may therefore be utilized for
disposal of waste and overburden from succeeding benches.

In Indiana, where a greater part of the building limestone is produced,
most ledges are 120 to 140 feet in width to permit service by a derrick
boom ; sometimes blocks from the most remote parts of the ledge must be
dragged. At large quarries a series of derricks is set in line and a long
ledge worked down in a succession of floors until all the good stone is
removed. The line of derricks is then moved back 120 to 140 feet and
another ledge begun. Stripping and waste from the last operation are
thrown into the opening previously made; thus, a wide area may be
worked out in successive strips.

Stripping. — In the Indiana district red clay covers the limestone beds
to a depth of 1 to 20 feet or more. In some places it is stripped by power
shovels into worked-out pits. The hydraulic method is employed where
the surface contour favors washing the soil into abandoned pits or other
low-lying areas. Mud seams are usually present in the upper level, and
the hydraulic method is especially advantageous for washing clay from
such irregular surfaces. However, loose rock fragments mixed with the
clay may hamper removal by water, and some other process may be
better. Hydraulic stripping has been described in a previous chapter
(see pages 14 and 15).

A second phase of stripping involves the removal of overlying non-
commercial rock, which at many quarries occurs to a depth of 5 to 15
feet immediately beneath the clay covering. In some quarries near
Bedford 40 to 60 feet of such waste must be removed. The method of
removal is governed chiefly by the nature of its contact with the under-
lying beds. If it is separated from the good rock by a layer of clay,
shale, or an open bedding seam that serves as a cushion, it may be
drilled and blasted with light charges of black blasting powder without
danger of shattering the commercial rock. In some places, however, the
rock overburden is continuous with that of good quality, which under such
circumstances would be easily destroyed by the shock of an explosive.
In such cases it is necessary to channel the waste and remove it in blocks,
a stripping process almost as expensive as removal of good stone. A more
recent development is adaptation of a wire saw for making cuts beneath
the inferior rock, permitting explosives to be used without damage to the
underlying ledge.

Where mud seams extend through waste rock into marketable stone
the clay which accumulates during removal of the upper benches must be

THE STONE INDUSTRIES

removed as a floor-cleaning operation, which is not properly regarded as
stripping.

Channeling. — After all overburden is stripped from the rock surfaces
the next step is to make primary channeling-machine cuts for block separa-
tion. A channeling machine operates with a chopping action similar to
that of a reciprocating drill. It is mounted on a frame with four wheels
and travels back and forth on a track. The cutting tool comprises three
or five steel bars sharpened to a blunt chisel edge and solidly clamped

Fig. 4.-

-Steam channeling machines at work in an Indiana Hmestone quarry.
Indiayia Limcstojie Company.)

{Courtesy of

together. When three bars are used the cutting edge is in the form of the
letter A^; when five are used they are in the form of two such letters, or
with the second A^ reversed. On channelers of one type the cutting tools
are secured with wedges to an upper and lower clamp. The bars are
undamped and lowered after every 6 inches of channel cut, and at a
depth of 5 feet the 9-foot steel is changed for bars 14 feet long. On
another type — the duplex electric channeler — the bars are set in a cross-
head and changed every 2 feet. Steam channelers were once the only
kind used and are still employed to some extent. They cut faster than

LIMESTONE 47

other types but require more labor. A steam boiler is attached to the
machine which cuts a single channel. The blows of the channel head are
actuated by a piston in a cylinder, the action being similar to that of a
steam drill. Steel is changed about every 2 feet. Some are of the
duplex type, but both machines work in the same channel. Single
channeling machines are advantageous for cutting unusual widths.
Steam channelers are shown in figure 4.

The duplex electric channeler is now widely used. The chopping
action is accomplished with cranks driven by 25-h.p. motors and intensified
by heavy springs. The machine operates on a track of 7-foot 2-inch
gage and cuts a channel on each side. The cuts are 8 feet 4 inches to
8 feet 5% inches apart and may be 8 to 12 feet deep. The cutting edge
of the steel is IJs to 2% inches wide and cuts a channel about 2 or 23^:4
inches wdde. The steel is reduced one-eighth inch for each change.
Cuts may be 50 to 100 feet in length; for long cuts several machines
operate on the same track. Some large quarries keep 20 or more machines
in use.

When a pair of cuts is completed the tracks are moved and a second
pair made. On the completed floor they average 4 feet apart, but occa-
sionally are narrower or wider. In some regions channels are cut parallel
with the east-and-west mud seams, while in other places they are at right
angles to them. Cross channels are made only for wall cuts, for removal
of key blocks, or as "head cuts" to divide strips that are too long to be
turned down en masse.

Where mud seams are present the first cuts are made wdth some
difficulty. Tracks must be supported with posts and scaffolding. It is
difficult to keep a cut straight on an uneven surface, and channeling
becomes slow and tedious until it has passed the irregularities. The
addition of water is not feasible until a fairly continuous channel is
obtained; therefore, cuttings must be removed by hand. In the regular
process a stream of water carries away the cuttings as thin mud, and
cutting is much faster wet than dry. After the quarry floor is leveled it
is relatively simple to move and place tracks.

The rate of channeling is difficult to determine because some operators
measure it in terms of actual cutting time, while others estimate on the
basis of average accomplishment over a long period. The most reason-
able time basis is "channeling hours," that is, the time for which machine
operators are actually paid. Using such a basis for time, and regarding
1 square foot of channeling equivalent to 33^^ cubic feet of gross produc-
tion, the calculated daily rate is 200 to 300 square feet for each duplex
machine. Most operators will estimate a faster rate, but they fail to
allow fully for all interruptions. The cost of channeling is 8 to 12 cents a
square foot; in fact, it is the largest single item of quarry cost and may
exceed half the total cost.

THE STONE INDUSTRIES

Wire Sawing. — The high cost of channeling has led some operators to
attempt more economical methods. The unqualified success of the wire
saw in Pennsylvania slate quarries offers encouragement, for there a wire
saw will do the work of two or three channeling machines with much
lower first cost, as well as lower operating expense. The wire makes a
cut only about one-fourth inch wide and thus wastes little rock as cuttings.
No tracks are required, the saw may be operated by one man, and the
power charge is small. It is particularly advantageous in cutting upper

Fig. 5.

-Method of cutting and removing key blocks in a limestone quarry.
Indiana Limestone Company.)

{Courtesy of

irregular beds. Its design and operation are described in detail in a
subsequent chapter on slate (see pages 255-260).

Two Indiana companies were using this equipment with fair success
in 1931. In one quarry a cutting rate of 26 square feet an hour was
attained under rather unfavorable conditions. Another company made
quite exhaustive tests in 1931. A cutting rate of 87 square feet an hour
was attained, and the average cost during the second month of operation
was 11.2 cents a square foot. Details have been published by Newsom,^
who directed the work.

Removal of Key Block. — In opening up a new floor where no free
face is present the most difficult task is removal of the first or key block.

» Newsom, J. B., Results of Wire-saw Tests. Trans. Am. Inst. Min. and Met.
Eng., vol. 102, 1932, pp. 117-121.

LIMESTONE

The block is channeled on four sides, and wedges are driven in the cuts
to break it free at the floor. In some quarries, after an 8- by 8-foot
block has been channeled the tracks are shifted, and two 2-foot blocks
are channeled as shown in figure 5. The narrower masses, known as
"pulling blocks," usually are comparatively easy to break loose by
wedging in the channel cut. When the block is free, corners are chipped
from the edges of the cuts to make room for the dogs or hooks, and the

a 1

Fig. 6.

-Arrangement of channel cuts for removing key blocks.

blocks.

a, 2-foot channel; 6, key

block is hoisted out, as shown in the figure. If only part of the block
is thus removed the process must be repeated with the lower sections.
If unusual delay and difficulty are experienced in removing the first
block, it may be advisable to break it up and remove it as waste. When
it is out of the way floor space is provided for removing succeeding blocks.
They are wedged free at the floor and removed one by one, providing a

^---.

A B

Fig. 7. — Diagram showing effect of rift on floor breaks, a, dip of rift; 6, wedge holes.
A, break in a direction up the dip of rift giving uneven floor; B, break in a direction down
the dip of rift giving a more uniform floor.

wider working space. Another method of removing key blocks is
shown in figure 6. The pulling blocks are in the center, as indicated.
A mass 2 feet wide is removed along the wall to provide space for slush
from the channelers. A third long cut is made 20 feet from the 2-foot
space, and crosscuts 4 feet apart are subsequently channeled. When the
pulling blocks are removed the 4- by 20-foot masses are turned down as

THE STONE INDUSTRIES

usual. Various modifications of the method are in use in different
quarries.

Bed Lifting. — After masses of rock 4 feet wide, 8 or 10 feet deep, and
50 or 60 feet long are channeled, the next step is to separate them at the
floor line by drilling and wedging. An air-driven hammer drill is used
to sink a series of holes 8 to 12 inches deep, 1 foot to 18 inches apart,
slanting a little downward from points near the floor line. They are not
made at right angles to the wall but at such an angle that wedges placed
in them may be sledged conveniently. They slant right or left, depend-
ing on whether the sledger is right- or left-handed. Plugs and feathers

Fig. 8.

-Method of turning down blocks in an Indiana limestone quarry.
Building Stone Association of Indiana, Inc.)

{Courtesy of

are placed in the holes and driven in succession until a floor break is
made. At intervals wedges are driven to full depth, and the pressure
being thus relieved most of them may be removed.

Commonly the rift of the rock is inclined at an angle of 5° to 10° from
horizontal, which may result in a very uneven floor. It is best to quarry
in such a way that floor breaks are made in the direction of dip of the
rift, which then tends to hold or guide the break to the bottom of the
channel cut, as shown in B, figure 7. If a break is made in the opposite
direction it will follow upward on the rift from the bottoms of the shallow
drill holes and reach a point several inches above the bottom of the
channel cut, as shown in A, figure 7. The floor will then consist of a
series of humps and hollows, and much waste rock will result.

LIMESTONE

More uniform breaks could probably be made by drilling some of
the holes almost the full width of a block and using long wedges in
them — a method in common use in marble quarrying — but apparently
such a plan has not been tried in limestone.

Turning Down Blocks. — After a block is wedged free it is turned down
in a horizontal position on the quarry floor before further subdivisions
are made. On a long block two notches or dog holes are made in the
back channel cut, wide enough to accommodate massive hooks. By
means of sheaves and tackle these are connected with another pair of
hooks firmly secured to the quarry floor some distance in front of the face.

Fig. 9.

-General view of a limestone quarry. (Courtesy of Building Stone Association of
Indiana, Inc.)

When a heavy strain is exerted on the cable by the derrick hoist the
block is gradually pulled over, as shown in figure 8. Bull wedges may
be sledged in the back channel cut to assist the process. Piles of broken-
rock "pillows" are so placed that the block falls on them and comes to
rest with little impact and without danger of breaking. Such "pillows"
are shown in figure 8. Figure 9 is a general view of a limestone quarry,
showing an unusually large mass of stone just turned down.

Subdivision of Blocks. — The next step is to divide the mass of stone
into commercial sizes. It is first laid out with a carpenter's square and
straightedge ; and if more than one grade of rock is present, a longitudinal
break is made between the grades. All subdivisions are made by plugs
and feathers or "slips and wedges," as they are called in Indiana. Holes

THE STONE INDUSTRIES

are drilled in line, 6 to 8 inches deep and 12 to 18 inches apart. Indiana
limestone may be drilled rapidly. One man with a hammer drill can
sink about four holes a minute. Plugs and feathers are then placed
therein. "Feathers" are strips of iron flat on one side for contact with
the wedge and curved on the other to fit the wall of the drill hole; two
are inserted in a drill hole, and a "plug" (a steel wedge about 6 inches
long) is driven between them. They are sledged lightly in succession,
beginning at one end of the line, to maintain an even strain on the rock.
Sledging is continued until a fracture appears. Common block sizes

Fig. 10. — Method of subdividing and hoisting limestone blocks. (Courtesy of Indiana

Limestone Company.)

are 10 by 4 by 3 feet and 10 by 4 by 4 feet. Where mud seams occur
or where separations must be made according to grades, many irregular
sizes may be produced. Figure 10 shows the method of subdividing
blocks.

Hoisting. — Steel or wooden derricks of about 30- to 50-ton capacity
are used for hoisting blocks from quarries. The derrick masts, of
swinging-boom type, are supported by 12 to 15 guy cables secured to dead
eyes in the rock or attached to buried timbers. Derricks now in use have
masts 80 to 110 feet high and booms 70 to 100 feet long. "Dog holes"
are cut on opposite sides of a block to hold the tips of grab hooks (dogs).
A chain passed through the eyes of the hooks draws them firmly against
the block, holding it securely, as shown in figures 5 and 10.

LIMESTONE 53

The end block is first raised about 3 feet at the outer end and lowered
again to the floor. This procedure crowds it outward, making a space
of a foot or more for attaching dogs. Dog holes are cut, hooks attached,
and blocks removed in succession and placed on cars or piled for later
disposal. Workers become very skillful in choosing positions for attach-
ing dogs so that blocks are balanced exactly. Each block is marked
with letters or numbers in black paint to indicate its classification and
for use in office records.

Cleaning Floor. — Waste-rock fragments, muddy cuttings from
channeling machines, and clay from seams extending downward from the
surface accumulate on the quarry floor and must be removed before a
succeeding floor is channeled. The cleaning of floors is usually slow,
costly, and somewhat disagreeable, especially in rainy weather. Waste
is shoveled by hand into great iron dump pans, which are hoisted out
and dumped into abandoned pits with the quarry derrick. If much
waste accumulates a power shovel may be used.

Transportation and Storage. — As the average quarry block weighs
10 to 12 tons standard railway cars are invariably used for haulage.
Large storage capacity is essential, for enough stone must be accumulated
to supply the demands of the four winter months when quarries are
idle. Outdoor storage or "stacking yards" may be maintained at quar-
ries, at mills, or at both places. A common method of storage is to pile
blocks within reach of derrick booms. They are usually piled high in a
limited area, and at times it is difficult to sort them. Overhead traveling-
crane storage is preferred by some operators, because the blocks are more
accessible and handled more quickly.

Scabbling. — Some companies quarry only, and sell rough blocks to
stone mills; others have both quarries and mills. Companies that own
no mills frequently ship blocks to distant points, and these must be
trimmed carefully to avoid freight charges on waste. The process of
trimming blocks to uniform rectangular shape is known as "scabbling."
It may be done at the quarry or storage pile and is, therefore, a sort of
transitional process that may be classed with either quarrying or milling.

Several methods of scabbling are employed. Scabbling picks
similar to ordinary miners' picks are commonly used to remove all
irregularities. One point is bent at a sharp angle toward the handle
for use in chopping dog holes for attaching grab hooks. Hand picks and
spalling hammers also are employed to remove corner masses from
blocks to be turned into columns. For squaring up ends of blocks some
companies use two heavy disks of iron about 3 feet in diameter which
run in opposite directions but in the same plane and with their peripheral
edges nearly meeting. On the face of each disk are attached two single
and one pair of cutting tools. As a block travels on a car the rotating
disks cut down the surface. Blocks scabbled with this machine are

54 THE STONE INDUSTRIES

easily recognizable by the two sets of semicircular grooves or markings
on their surfaces.

Scabbling saws are preferred by many, not only because they leave
a smooth, even surface, but also because in a single operation they remove
large projections which must be removed piecemeal by the pick or disk
method. Scabbling saws are of various types. Diamond-toothed drag
saws are used singly or in parallel pairs adjustable for width. Diamond-
toothed circular saws (commonly of 60- or 72-inch diameter) cut rapidly,
and if mounted in pairs adjustable in spacing may scabble both sides of a
block at once. The greatest limitation of the circular saw is the depth
of cut, as it can reach only from the arbor to the rim; a 60-inch saw can
cut only 26 or 27 inches deep and a 72-inch saw, 32 or 33 inches. This
difficulty is overcome by making one pair of cuts to the maximum depth
the saws will reach and then turning the block over and cutting from the
reverse side. If the cuts fail to meet the intervening rock is easily
broken.

A clever adaptation of a Carborundum scabbling saw has been
observed. The saw is mounted at the end of a shaft and secured with
counter-sunk set screws flush with the outer surface. When a cut is
made as deep as the arbor will permit the scabbled slab is broken off
with a hammer; and a second cut of equal depth may be made, for the
smooth outer surface of the blade interferes in no way with the sawed
surface of the block.

Scabbling planers are effective substitutes for saws. Rough blocks
are placed on a bed which travels between two sets of massive blades set
at right angles to the block and with edges vertical. Irregularities are
thus scraped from the surfaces of the stone. By screw-feed adjustment
the cutters are set closer after each motion, until a smooth surface is
obtained. On blocks 6 feet high each cut removes i^ inch of stone and
on blocks 4 feet high, 3^^ inch. About three blocks may be scabbled an
hour. A wire saw consisting of a ^{q- or H-inch three-strand cable
running as an endless belt driven by an electric motor is also used for
scabbling. Where the wire comes in contact with the stone it is fed with
sand and water. Several blocks may be lined up and cut at the same
time. The equipment may be operated by one man, and an average
cutting rate is 20 to 25 square feet an hour.

Various sawing methods are emploj^ed for slabbing off the sides of
blocks; but the ends are usually scabbled with picks, although they are
sometimes cut with wire saws or circular disk scabblers. The state-
ment has been made that rough, scabbled blocks weigh abolit 200 pounds
a cubic foot sale measurement, whereas smooth blocks weigh only 180
pounds a cubic foot, which indicates the advantage of scabbling by saw
or planer. Scabbling is done most carefully where blocks are prepared
for export trade or for shipment to mills long distances from the quarries.

LIMESTONE 55

MILLING METHODS

Mill Processes. — Quarried blocks are taken to mills for fabrication
into finished products ready for use in various types of construction.
Briefly, the steps in mill operation are drafting and pattern making,
block transportation, sawing, planing (including curved and molded
work), jointing, milling, turning, fluting, cutting, carving, packing, and
shipping. These processes are considered in some detail in the following
paragraphs.

Drafting and Pattern Making. — Before any cut-stone job can be
begun accurate detailed drawings must be made of every piece of stone
that differs from another in size or shape. Architects' drawings are
usually insufficient, for the stone must be fitted accurately to the steel
framework, and detailed data of the size and position of each steel
member are necessary before stoneworkers' shop drawings can be made.
These consist of elevations showing the position and dimensions of each
piece of stone. Some sizes and shapes may be duplicated many times in a
building; others may not be duplicated at all. Patterns for molded and
carved work are of zinc or other soft metal ; sometimes paper patterns or
stencils are used. For the most intricate carved work plaster models
are supplied by the stone mill or by the architect.

Few people realize how much labor and expense are involved in the
drafting required for a large stone structure. This so-called "paper
work "may cost one-half to two-thirds as much as the entire quarry
expense of supplying the rough blocks of stone.

Ticket System. — After shop drawings are made draftsmen prepare a
card or ticket for every block of stone. On each ticket is a drawing of the
block with exact dimensions indicated. A number is assigned, and if a
pattern is to be used the pattern number is given. Even though many
blocks of one kind are to be made a ticket is prepared for each. The man
in charge of gang-sawing first gets the ticket and cuts the block required.
As this piece of stone passes to the planer, jointer, and all subsequent
machines and operations, the ticket goes with it, and each workman
consults it before any work is begun. By this means workmanship is
constantly verified, and very few mistakes occur. The highest degree
of care and skill is required, for one small error in measurement or one
wrong blow with a tool may ruin a block on which much labor has been
expended. The above system is used particularly in Indiana. In some
New York mills one ticket or schedule is used for all blocks of a general
shape.

Handling Blocks. — Overhead traveling cranes with at least 70-foot
spans and lifting capacities up to 50 tons are used almost universally.
Mills are of two general types. Some are wide and equipped with two
pairs of crane tracks, one for a heavy crane used in handling quarry

56 THE STONE INDUSTRIES

blocks and placing them on the saw beds, while the second pair is
furnished with lighter, more rapidly moving cranes for conveying
smaller blocks as they pass from one operation to another. Some
means of transferring stone from heavy to light cranes is required. Other
mills are long and narrow, with one pair of tracks on which several
cranes operate. For example, there may be a 25-ton-, a 15-ton-, and a
71^^-ton-capacity crane on the same tracks. Some are of the three-motor
type, one of which is used for propelling the entire crane from one end of
the mill to the other, one for lateral motion to cover any point from side
to side, and one for hoisting. Most of them are of the two-motor type,
one motor with two friction clutches serving for both lateral motion and
hoist. In a very short time a block may be picked up at any point in a
mill and placed at any other.

Railway tracks enter the mills across the end, down one side, or across
the middle. They bring quarry blocks to the mills and carry away
finished products. All rough blocks and single unfinished slabs are
handled with grab hooks; finished and semifinished blocks or piles of
slabs, with cable slings or with slings of rubber belting to avoid damage to
corners and edges. Operators travel back and forth in cabs attached
to the crane. Some cabs are attached to one end of the crane, the
operator always being near one wall ; others are attached to the buggy
that moves back and forth from one side of the mill to the other. The
latter type has the advantage of placing the crane man always immediately
above the blocks handled, so that he can guide the movement accurately
and quickly. A ground force usually consists of two men, known as
"hookers," who attach and release hoisted blocks and signal the crane
man. This work requires much rapid walking back and forth in the mill,
for cranes travel at high speed, and after hooks or slings are attached,
hookers must as quickly as possible reach the point where the block is to
be placed.

Sawing. — The first step in manufacture is to saw rough blocks,
into either slabs or blocks, of the required dimensions. Gang saws
are almost universally used for this purpose. They consist of a series
of soft steel blades set in parallel position in a frame which has a
backward and forward motion. These blades may be spaced as desired
for thin slabs or thick blocks. Gangs vary in dimensions, one of average
size being 14 feet long, 8 feet high, and 8 feet wide.

Abrasives are fed to the blades with water; those most commonly
used are clean silica sand, most of which is obtained from Ottawa, 111.,
and "chats," a name given to a cherty rock obtained as gangue at the
Missouri lead and zinc mines and crushed to the consistency of sand.
Steel shot is also employed, chiefly to obtain the deeply scored, "ripple-
mark" surface desired for some architectural effects. When this type of
abrasive is used the blades are notched on the lower edge and used in a

LIMESTONE 57

straight-line drag-saw frame. Most gangs are of the swinging type and
are suspended from above by nearly vertical rods attached to the two
ends. As the frame moves back and forth, actuated by a crank and
connecting rod (pitman), the cutting blades lift toward the end
of each stroke. This permits sand to wash under them, and as they
start back on the return stroke the blade bears down on the sand which
abrades the stone rapidly. Some gangs have a straight backward-and-
forward motion, but the swinging type is more common. Sand or chats is
collected in a concrete trough beneath the gangs and pumped to a box
above the saws from which it is distributed, with fresh abrasives, to the
cutting blades. If much shot is employed it is shoveled for reuse rather
than pumped. An adjustable automatic gear feeds the gangs downward
at any desired rate. In the Indiana limestone district an average rate is
about 6 inches an hour.

A straight steel blade with diamond teeth on the lower edge is used as a
drag saw for making single cuts. A drag tooth is mounted with six
diamonds of about three-fourths carat size placed in alternate positions
on opposite sides of the cutting face. A single tooth may cost $40 or $50.
This saw will cut at a rate of 30 to 40 square feet an hour.

Circular diamond saws are used almost universally for making sub-
sequent cuts. Common sizes are 60 and 72 inches in diameter, though
smaller ones are sometimes employed. The blades are of steel one-fourth
inch thick, with a series of square notches around the rim. Steel teeth
mounted with diamonds are set in the notches and held in place with
copper rivets. A 60-inch saw, a size widely used, has 84 teeth and a
72-inch saw, 110 teeth. Teeth for rip saws designed for heavy service
are supplied with two 3^^- to ^s-carat diamonds. Jointing-saw teeth
contain 6 to 10 smaller diamonds, which give reasonably smooth stone
surfaces and cause less breakage of corners than ripsaws. Circular-saw
teeth cost $8 to $11 each. Extreme care and most exacting workmanship
are required in the manufacture of diamond circular saws to insure
accurate balance, uniform cutting, and true running. Each saw is
designed for a standard speed (11,000 to 13,000 surface feet a minute)
and should be run at no other. With care, a saw will perform constant
service for 6 months to a year without being conditioned. Resetting
costs about $1 a tooth if no diamonds are lost.

A ripsaw has a stationary mounting, and a bed actuated with a worm
gear carries the block of stone beneath it. An exception is the gantry
saw, which is mounted on a wheeled frame that travels on a track after
the manner of a gantry crane and spans the block resting on a timber bed.
A jointing saw is mounted on a movable frame actuated by worm gear,
which carries the saw through the stone.

The cutting edge of a diamond saw is cooled with a stream of water,
which also carries away the cuttings. An average sawing rate is 3 to 16

58 THE STONE INDUSTRIES

inches a minute, depending on the depth of the cut. Ripsaws cut faster
than jointers. The first cost of a diamond saw is high, but it cuts
rapidly, and with care maintenance cost is low.

Silicon carbide (Carborundum) circular saws are also in common
use. They are usually smaller than diamond saws and are of two
types — continuous rim, which are more generally employed, and toothed,
which are larger, approximately 30 inches or more across. They give
excellent service for the smaller cuts, as they leave smooth surfaces and
are less liable than diamond saws to chip the corners of stone blocks.

Some experiments are being performed in mounting saw teeth with
extremely hard alloys, such as tungsten carbide. Commercial develop-
ment has scarcely been attained, but the field offers wide possibilities.

Planing. — Planers are used for cutting stone blocks and slabs to
smooth surfaces and desired thickness and also for cutting moldings.
The frame that holds the cutting tool has lateral and vertical motion,
actuated by power-driven worm gear. The cutter is placed in position,
and a block of stone is carried beneath it on a traveling bed called a
"platen" at a rate of 30 to 45 feet a minute. A thin layer of stone is
thus scraped from the surface, and the process is repeated until proper
shapes or dimensions are obtained. Machines are equipped to cut tops
and sides of blocks simultaneously. For cutting moldings tools are
shaped in the blacksmith shop to fit exactly against patterns; that is, the
tool is the reverse of a pattern. If a great length of molding of one
profile is to be made, a Carborundum wheel, shaped in reverse form
or as a negative of the pattern, may be used, but in limestone the planer
is employed more commonly for this work. For both flat and molded
work the planer is a time saver, its estimated production being equivalent
to that of seven stone cutters using hammer, chisel, and modern pneu-
matic tools.

Planers are adaptable for curved as well as straight work. A second
bed or platen, capable of rotating through an arc of a circle, rests on the
regular bed. On some planers an arm pivoted on a fixed point at one
side is connected with the upper bed, and its length governs the curvature
of the arc. Another type is guided by a pin following any one of a
series of curved grooves having different radii. If a radius approaching
12 or 14 feet is required, it is accomplished through movement of the outer
end of the bar in a slot set at an angle. A stone block is placed on the
upper bed, and when the planer is operated in the usual way the tool
cuts a curved form, the shape of which is governed by the motion of the
block and the pattern of the tool. Garden seats and arches for doors,
windows, or ceilings are made with such machines.

A Carborundum planer consists of two saws with a drum of smaller
diameter between them, all of silicon carbide. The saws trim the sides
of slabs while the drum smooths the upper surfaces. The planer bed

LIMESTONE 59

travels at a rate of only 20 to 30 inches a minute, but it finishes the job
in one cut and accomplishes much more in a given time than an ordinary
planer with which many successive cuts may be required.

Turning and Fluting. — Lathes are employed for turning columns,
balusters, and similar forms. Large columns are first scabbled to
cylindrical shape and then mounted in lathes, essentially the same as
those used for wood or metal turning. The column rotates against a tool
actuated by machine-driven worm gear traveling slowly back and
forth the full length of the stone. The tool post is moved forward or
backward by a hand or automatic screw feed, which may be adjusted for
any change in diameter required for tapered columns. Limestone
columns are turned to a smooth surface, but final rubbing is usually by
hand. Ordinary lathes will handle 15- to 30-foot columns, and some are
specially designed for massive 50- or 60-foot columns. Smaller sizes
are used for balusters.

Many columns are fluted, the fluting is done on a lathe. A column
is first turned to the desired outer dimensions. The width and length of
the flutes are then laid out on the surface with pencil. The column
remains stationary while the fluting tool attached to the tool post of the
lathe travels back and forth. This process is continued until the line
bounding the flutes is reached. If a column is tapered the flutes may be
cut to shallower depth on the smaller parts of the column, which auto-
matically makes them narrower. When a flute is completed the column
is rotated with a hand bar, and the process repeated in the new position.
After this machine work the ends of the flutes are finished with pneumatic
tools, and the column is rubbed by hand. Carborundum fluters are
also used. A Carborundum wheel cut as a negative of the pattern is
generally used for making balusters, particularly if many of one kind
are to be fabricated.

Milling. — Some confusion exists in application of the term "milling."
The word is used in a general way to cover all mill processes, such as
sawing, planing, cutting, or carving, and is also applied to a particular
type of equipment known as a mflling machine. This machine consists
essentially of a rotating head with right-and-left and vertical worm-gear
motions. A movable platen provides front-and-back motion. The
head carries tools of various sizes and shapes, by means of which stone
may be cut in irregular patterns. This machine is particularly advan-
tageous in preparing for the carvers blocks in which deep recesses must
be cut, for it removes the bulk of the stone much more rapidly than it
can be cut away with hand tools. A skilled milling-machine operator
can outline lettering and intricate patterns, thus reducing hand carvers'
work substantially.

Cutting and Carving. — Cutting is usually defined as straight-line
work and carving as curved work. Carving requires more skill than

60 THE STONE INDUSTRIES

any other limestone-cutting operation and is usually done by experienced
workers. Many years ago all carving was done with chisel and mallet,
and these tools are still necessities for certain operations. Modern
pneumatic tools, however, have revolutionized the art and greatly
increased the production per man. The great bulk of the work is now
done with them.

At first the use of compressed-air tools was vigorously opposed.
It was feared that the art of stone cutting would be destroyed, and that
health would be impaired through vibration of the tools. Such fears were
unfounded, for pneumatic tools enhance the skill and artistry of the
carvers and lighten labor to a marked degree. Many a stonecutter of
advanced age, who could not bear the strain of constant toil with chisel
and mallet, has found his labor so lightened by pneumatic tools as to
add several years of active work to an already long experience.

The stonecutter uses a great variety of tools, heavy ones for removing
larger fragments when blocking out a design and smaller ones for com-
pleting the work. Intricate carving may require tools almost as fine as
those of a dentist. Patterns insure accuracy and symmetry. A pattern
may be placed on the surface of the stone and marked around the border
or through perforations, or the design may be transferred by dusting
with burnt umber. Models of the most complicated figures are made in
plaster of paris, and reproducing them in stone is work of the highest skill.

Carving adds greatly to the expense of preparing stone. Architects
who design structures requiring much hand carving must expect a cost
per cubic foot much higher than that for buildings consisting of plain
blocks. Oolitic limestone, however, carves more easily and tends to
split on the bed less than most other limestones, bringing it within
a cost range which greatly widens the field of carved-stone architecture.
Many beautiful structures, churches, chapels, libraries, and other
public buildings bear witness to the adaptability of oolitic limestone for
carving.

Finishing. — Much limestone used in buildings has no other surface
finish than that given by machines with which it has been worked. Cer-
tain parts, however, such as columns, may require smoothly rubbed
surfaces. Usually final finish is done by hand, the stone being rubbed
down wet or dry with sandstone, sand and water, or bricks of artificial
abrasives. A small electric-driven disk faced with sandpaper may
finish flat surfaces. Steel scrapers are also used and wire brushes
employed to brush all cuttings from the surface.

Nature of Finished Surfaces. — Architects and builders demand
various types of surface finish, A tooled surface, which is covered with
fine grooves in parallel lines, is made with a pneumatic or planer tool
having fine teeth. A bush-hammered surface is rough and pitted, as the
hammer used has a face covered with small projections. A hand-picked

LIMESTONE

surface is indented with a sharp-pointed tool, A small-fluted surface has
small, parallel corrugations. A four-cut surface is made with a planer
tool that has four corrugations to the inch. A rubbed surface is smoothed
by hand rubbing with sand and water or some other abrasive. A shot-
sawed or ripple surface is deeply scored or grooved by using steel shot as
abrasive for the gang saws. Chat-sawed stone is rough but smoother
than the shot-sawed. The chats used as abrasive in sawing are of
three different grades of fineness to give smoother or rougher surfaces as
desired.

Preparation for Shipping. — Building stone is a product so heavy that
provision must be made for handling all blocks by machinery, in such a
way that corners or edges will not be broken. For smaller pieces a pair

Fig.

-Interior of a limestone finishing mill

Limestone Company.)

of converging holes is drilled in an edge or face that will be covered when
the block is in final position in a building. Lewis pins, with eyes at the
top, fit loosely in the holes. Through them a chain is passed, and as it
is drawn tight the pins bind so firmly that the block can be hoisted safely.
For large, heavy blocks Lewis key pins are commonly used. The holes
which are drilled for them are enlarged at the bottom. The two side
keys are wide at the base and held apart in the hole with a center key
inserted last. All three are secured with a bolt which passes through
holes in their upper ends and also holds a ring for hoisting. Much
handling is done with slings or chains, lumber being used to protect the
edges. All blocks are numbered and lettered, to show their positions
in the structure in which they are to be placed, and carefully packed for
shipment, usually in open-top gondola cars. Each block is surrounded
with excelsior and limestone dust and packed so solidly that no damage

62 THE STONE INDUSTRIES

can result during shipment. For the Department of Commerce Building
in Washington, D. C, one of the largest stone buildings in America,
nearly 70,000 blocks of Indiana limestone averaging 1,500 pounds in
weight were used; 1,100 railway cars were required to haul the finished
stone.

Figure 11 illustrates the interior of a modern limestone finishing mill.

LIMESTONE PRODUCTS

Some companies quarry and saw only, selling the stone in blocks
or slabs. Standard-size blocks are most salable and command the highest
price. Because of the presence of mud seams or other reasons odd-size
blocks, usually designated "chunks," are necessarily produced. The
quarry operator who has no mill suffers some disadvantage, for while
off -size blocks may with judicious management be utilized to advantage
they are not disposed of readily and command a low price.

A second and larger group of companies both quarries and manu-
factures stone into finished products. The mills are either at quarries
or in near-by towns, the latter usually being preferred because the labor
requirement is large, and living conditions are more favorable than in
most quarry regions. A third group of companies buys sawed or rough
stock and manufactures products, but does not operate quarries.

Therefore, rough blocks, slabs, and cut stone or other forms of
building stone are the products chiefly marketed. Cut stone includes all
types of finished blocks, columns, sills, moldings, balusters, and carved
stone. It is the chief, though not the only, product of many limestone
mills.

A rougher type of building stone, known as "sawed or broken ashlar,"
is not usually regarded as a cut-stone product. It is particularly adapted
for residential work, though it is also used in larger structures. It is
much less expensive than cut stone and thus brings homes, having the
permanence and dignity of stone, within the cost range of people of
moderate means. This type of ashlar is fabricated in sawed strips usually
3 or 4 inches thick and in different height units that will combine to give
even-range levels if desired. It is sold either in strips, cut on the job
to specified or standard lengths that will fit together and make even
corners with very little cutting, or sawed on four sides and broken to
give various lengths. Random sizes and mixed colors give very attrac-
tive effects. Rough ashlar is comparatively inexpensive, because it
requires no drafting or pattern-making, no machine work except sawing,
no cutting or carving, and no careful packing for shipment and because
it may be set by a stone mason or brick layer. Its use is advantageous
to the producer because it permits him to use many small sizes that
would otherwise be wasted. It is of benefit to the user because it makes

LIMESTONE 63

it possible to build innumerable homes of moderate cost, low upkeep
expense, high rental and sales value, and attractive, dignified appearance.

COST OF QUARRYING AND MANUFACTURE

Quarrying and milling costs are both variable because they depend
on conditions that may be quite diverse in different localities, for example,
depth of overburden, degree of hardness of the rock, type of equipment
used, working efficiency, skill of the workers, and size of operation. The
general range of quarry costs is 20 to 30 cents a cubic foot of block stone.
The chief item is channeling, which ranges in cost from 8 to 12 cents a
cubic foot of recovered stone.

Milling costs are extremely variable because some blocks have little
work expended on them, and others require much labor. Sawing is a
heavy item of expense, the subdivision of rough blocks into slabs by gang
saws costing 35 to 45 cents a cubic foot of finished product. Sawing in a
second direction (jointing) costs 12 to 15 cents more. Planing, milling,
and cutting costs must be added for most products. Carving is very
expensive because so much labor is required per cubic foot produced.
Gothic carving is one of the most difficult operations to estimate; it
may cost as much as $7.50 a square foot of surface carved. The handling
of material is an item that should not be disregarded. Paper work,
including drafting, shop drawings, tickets, and patterns, may cost 15 to
20 cents a cubic foot on average jobs and exceed $1 a cubic foot on elabo-
rate structures. For jobs requiring a moderate amount of carved work
the total cost is $1.50 to $2.50 a cubic foot. If much carving, column
cutting, or curved work is demanded it may be much higher.

WASTE IN QUARRYING AND MANUFACTURE

Rock of inferior quality, which is regarded as overburden rather than
waste, usually overlies the Salem beds and is removed before quarrying
is begun. Aside from this overlying material, waste in the commercial
oolitic beds is high, and efforts are being made to discover ways in which
it may be reduced. Some of the waste is due to rock imperfections and
some to rock lost in quarry processes. The problem of waste has been
discussed in some detail by Newsom.*

Coarse texture was once regarded as a serious imperfection, but
tests have shown that coarse-grained stone compares favorably in
durability and strength with that of finer texture, and modern demands
for variety rather than absolute uniformity in texture have led to its
wider use. Fine-grained rock always has been in demand and still
commands a premium.

Erosion cavities filled with clay cause much waste, particularly
in the upper beds. Many small, irregular blocks, necessarily produced,

' Newsom, J. B., Quarry Waste in the Indiana Limestone District. Am. Inst.
Min. and Met. Eng. Tech. Pub. 444, 1932, 10 pp.

64 THE STONE INDUSTRIES

are discarded because they can not be used advantageously. Incipient
seams or '^drys/' small cracks difficult to detect, must be carefully
avoided. Some quarries contain many of them, and others have very
few. They are excluded so carefully that they are rarely seen in blocks
used for building. Stone is sometimes rejected because it is variegated in
color, but present demands have led to a wider use of such material.
Further waste results from quarrying processes. It is estimated that
1 square foot of channeling is required for each 33^^ cubic feet of gross
production. Therefore, if each channel cut is 234 inches wide at the
top, 4 to 5 per cent of the rock is cut away. Uneven floor breaks may
cause the loss of a zone of rock 1 foot or more deep at the bottom of
each floor. Crooked cross fractures, strain breaks, cutting of dog holes,
and other factors incident to quarrying further increase the waste. It
is estimated that not more than 40 per cent of the rock stripped and
blocked out in a quarry is recovered in usable form. Much high-grade
commercial material is also wasted as it passes through the mill in the
manufacturing process. Outside slabs from gang saws and rough ends
from jointers reduce the volume of every block by several per cent. Saw
blades convert much rock into fine mud. Each diamond-saw cut and
each stroke of a planer takes its small toll of stone, while in making
curved and irregular designs more than half of the mass may be cut
away. It is estimated that mill waste amounts to between 10 and 20
per cent of the gross footage entering a mill. The smaller percentage
is in mills where material is utilized to best advantage as, for example,
where cubical blocks are sawed diagonally to make two triangular corner
blocks or two cornices wide at one end and narrow at the other.

UTILIZATION OF WASTE

Limestone of commercial grade in the State of Indiana generally
analyzes 97 to more than 99 per cent of total carbonates. Building lime-
stones in various other States are also of high purity. Pure limestones
are useful for many chemical purposes, and some operators have sought
to develop markets that will absorb part of their waste materials. Some
high-grade material is burned into lime, which is used widely, not only
for mortar and plaster, but in paper mills and steel furnaces and for water
purification. Finer sizes of waste are used as agricultural limestone, in
glass factories, for tennis-court surfacing, as chicken grit, or as filler.
Many thousand tons from 4- to 12-inch size are sold as flux for open-
hearth steel furnaces, for which a very low silica content is demanded.
Many carloads of stone ranging from 1- and 2-man sizes to stones weigh-
ing 30 tons are sold as riprap and breakwater stone. Slabs of attractive
colors are sold as stepping stones, flagging, and for garden walks. If the
stone is suitable it may be utilized as railway ballast and concrete aggre-
gate. Mill ends and other small sizes are converted into ashlar. While

LIMESTONE 65

waste limestone can be used for many purposes, the amount consumed is a
mere fraction of the thousands of car loads of quarry and mill waste now
discarded.

LIMESTONE MARKETING

Under normal marketing conditions two-thirds to three-fourths of all
building limestone is sold as rough blocks or sawed slabs to mills situated
in large cities, where it is fabricated chiefly for small or moderate-size
building contracts. The balance of the production is manufactured in
mills operated in the quarry districts. Much of their output is devoted
to large projects. These mills, supplied only with shop drawings, can
fabricate stonework for a structure hundreds of miles away and can
supply in exact dimensions and in finished form thousands of blocks,
each fitted accurately for its particular position in the wall. Although
furnishing stone for large buildings directly from quarrying centers is
perhaps the most spectacular phase of limestone marketing, the impor-
tance of mills situated in consuming centers must not be overlooked.
They perform a vital function, for they supply stone to innumerable
users, many of whom require quantities too small to be obtained directly
from the great quarrying and milling centers.

The smaller limestone quarries in various States sell much of their
production directly to builders and contractors for local use. Some,
however, undertake fairly large building contracts or supply limestone
to be used in conjunction with other varieties of stone in both near and
distant projects. Some of it is handled through local mills in many
cities.

Bibliography

Anderegg, F. O., and others. Indiana Limestone, Efflorescence and Staining.
Purdue Univ. Eng. Exp. Sta. Bull. 33, 1928, 84 pp.

Ashley, G. H. The Geology of the Lower Carboniferous Area of Southern Indiana,
Indiana Dept. Geol. and Nat. Resources Twenty-seventh Ann. Rept., 1903.
pp. 83-84.

Beede, J. W. Geology of the Bloomington Quadrangle (including section on Utili-
zation of Waste Stone, by G. C. Mance). Indiana Dept. Geol. and Nat. Re-
sources Twenty-ninth Ann. Rept., 1914, pp. 190-312.

Hopkins, T. C., and Siebenthal, C. E. The Bedford Oolitic Limestone of Indiana.
Indiana Dept. Geol. and Nat. Resources Twenty-first Ann. Rept., 1897, pp.
291-427.

Kessler, D. W., and Sligh, W. H. Physical Properties of the Principal Com-
mercial Limestones Used for Building Construction in the United States. U. S.
Bureau of Standards Tech. Paper 349, 1927, 94 pages.

LouGHLiN, G. F. Indiana Oolitic Limestone; Relation of Its Natural Features to
Its Commercial Grading. Contributions to Economic Geology, pt. 1, 1929,
U. S. Geol. Survey Bull. 811, 1930, pp. 111-202.

66 THE STONE INDUSTRIES

Newsom, J. B. A Geologic and Topographic Section across Southern Indiana.

Indiana Dept. Geol. and Nat. Resources Twenty-sixth Ann. Rept., 1903, p. 281.
Richardson, C. H. The Building Stones of Kentucky. Kentucky Geol. Survey,

1923, p. 355.
Stone, Ralph W. Building Stones of Pennsylvania. Pennsylvania Topog. and

Geol. Survey Bull. Ml 5, 1932, 316 pp.

CHAPTER VII

SANDSTONE

VARIETIES

The term "sandstone" is applied to rock composed of small mineral
grains, usually quartz, which are cemented together more or less firmly.
"Conglomerate" is a name given to rock consisting of pebbles of various
sizes which are cemented together; if the pebbles are large and well-
rounded the rock is sometimes called " puddingstone " ; if angular in shape
it is called "breccia." "Quartzite" is a variety in which the individual
grains are cemented together with quartz so firmly that the rock fractures
as easily through the grains as through the cement. Some quartzites
look like massive quartz with scarcely a trace of their original fragmental
character. A "ferruginous" sandstone is one rich in iron and a "micace-
ous" sandstone, one in which mica flakes are prominent. "Arkose" is a
feldspathic or granitic sandstone composed of angular grains which have
resulted from the disintegration of granites, the debris thus formed
having been recemented into solid rock without any extensive water
action or decomposition. The siliceous sandstones may originate from
similar granite rocks, but they have been so thoroughly decomposed and
worked over by water before cementation that practically nothing is
left of the original rock except the rounded grains of quartz. A
"calcareous" sandstone is one containing a considerable amount of
calcium carbonate, and an "argillaceous" sandstone one containing an
appreciable amount of clay.

Sandstones are also named from their characteristic colors, such as
"bluestone," "redstone," or "brownstone." The term "bluestone,"
however, is applied to certain thin-bedded or easily cleavable sandstones
irrespective of color. The name "flagstone" is applied to sandstones
that split readily into thin slabs or sheets suitable for flagging. "Free-
stone" is a sandstone that can be cut or carved readily with equal ease in
all directions. "Canister" is a type of quartzite suitable for the manu-
facture of silica brick.

COMPOSITION

Sandstones consist essentially of quartz; some are nearly pure quartz.
Those consisting principally of other materials are rarely found, although
many contain minor quantities of feldspar, garnet, magnetite, and mica.
Muscovite or white mica is a common constituent. Iron oxides, calcium
or magnesium carbonates, and clay are other common accessory minerals.

68 THE STONE INDUSTRIES

SIZE AND SHAPE OF GRAINS

The grains of which sandstone is composed vary greatly in size.
Some sandstones are so fine-grained that they may be used for razor
hones. A screen test of a typical sandstone from the famous Amherst
(Ohio) district indicates that practically all the grains will pass through a
sieve having 40 meshes to the linear inch, and that one-third of the grains
are finer than 100-mesh. Sometimes the coarser, angular-grained sand-
stones are called "sandstone grits"; however, the use of this term is
often confusing because it is applied commercially to sandstones
which are well-adapted for abrasive purposes and not necessarily to
those of coarse grain; for example, the "Berea grit" of northern Ohio is in
places very fine-grained. Grains of sandstone may be well-rounded or
angular, depending upon the degree to which they were waterworn before
consolidation.

As pointed out in the section on the origin of sandstone, water has the
ability to sort and classify loose materials according to size. Some
deposits show remarkable uniformity in size of grains, a very desirable
feature. Usually the sizes of grains are nearly uniform throughout the
rock of one bed, and much greater variation is found in passing from one
bed to another. This is to be expected because sand of an individual
bed has been deposited under nearly uniform conditions over a wide area,
whereas succeeding beds may have been deposited after long intervals
and under quite different conditions of depth or water movement.

CEMENTATION

The usefulness of a sandstone depends greatly upon the nature of the
cementing material between the grains and the degree of cementation.
Of the four common cementing materials — iron oxides, clay, calcite, and
quartz — the last is most desirable, as it provides the strongest and most
durable stones. All stages of cementation are found in nature, from
incoherent sandstones that may be crumbled between the fingers to
indurated quartzites. All types between these extremes are used com-
mercially, but friable sandstones are useless as dimension stone. Some
sandstones are cemented more firmly in certain parts than in others.
Such lack of uniformity causes hard and soft spots, an undesirable condi-
tion for all ordinary uses.

As the cementing materials and degree of induration vary greatly
sandstones are the most variable of all common rocks in hardnQ^s, Con-
fusion may arise from this statement, for it may be supposed that as all
siliceous sandstones consist essentially of quartz, which has a hardness of
7, all sandstones will have the same hardness. However, this quality,
which is a measure of the ease with which stone may be scratched, is
governed by the degree of cementation, for scratching loosens individual

SANDSTONE 69

grains. Hardness, therefore, refers to the degree of adhesion between
grains rather than to the resistance offered to abrasion. In this sense,
therefore, it is synonymous with workability.

COLOR

. The purest sandstones are nearly white. Iron oxides are the more
important coloring agents. Limonite (2Fe203.3H20) usually gives
yellow, brown, or buff shades, and hematite (Fe203), darker brown or red.
Oxidation of iron-bearing minerals upon exposure may cause the rock to
change in color. If the change is uniform throughout, the general aspect
of the rock may not be impaired, but changes in streaks and spots may
detract greatly from the appearance.

Permanence of color is usually desirable. Generally the deeper
shades of red, brown, yellow, or buiT are permanent because they are due
to the presence of the stable iron oxides — limonite or hematite. Blue or
gray sandstones, which occur deep down in the lower ledges of a deposit,
may contain ferrous sulphides or carbonates which upon exposure will
oxidize to the more stable forms with gradual change to a buff or reddish
color.

Although it is generally claimed that uniform color is desirable, for
certain architectural effects diversity is now in demand. Blocks of stone
that would at one time have been thrown on the waste heap on account of
nonuniformity of color distribution are now being utilized for ornamental
building.

POROSITY

Sandstones are generally more porous than other rocks, although
quartzites may have as little pore space as granites. The percentage of
porosity of commercial sandstones ranges from 2 to 15. High porosity,
especially if the pores are small, is undesirable if the stone is exposed to
the weather in cold climates.

Pores or intergranular spaces in sandstone may be divided into two
classes — capillary and subcapillary. The former group includes openings
more than 0.00002 centimeter in diameter, and the latter, those of smaller
size. Water in pores of capillary size, termed "water of saturation,"
passes off readily when the rock is exposed to a dry atmosphere. Sub-
capillary pores contain "water of inhibition," which is released with
greater difficulty.

Normally the intergranular spaces of sandstone in an undisturbed
quarry ledge are completely filled with "quarry water," which, particu-
larly that part defined as "water of inhibition," carries mineral matter in
solution. When the water evaporates the dissolved material is deposited
as a cement between the grains, making the rock appreciably harder,
and subsequent wetting will not soften it. As evaporation takes place

70 THE STONE INDUSTRIES

at the surface, a sort of casehardening results. For this reason freshly
quarried sandstone works more easily than seasoned blocks. However,
some recent investigations indicate that the surface-hardening effect is
less pronounced than has been supposed.

The time required for the escape of quarry water depends on pore
size and rock structure. Rock with subcapillary pores requires a loijg
drying period, and one that parts easily along bedding planes usually
dries more quickly than one with no rift or direction of easy splitting.
If sandstone is exposed to frost action while the pores are filled with
water, the expansion caused by freezing may result in serious disintegra-
tion. Blocks should therefore be quarried in time to dry before a heavy
frost. Quarrying is usually suspended in cold climates during the late
fall and winter. Sometimes quarries are protected from damage in
winter by flooding them with water, scattering quarry refuse over the
floor, or covering the vertical face with cornstalks.

USES

Building Stone. — Sandstone is used principally for exterior and
interior building; that having siliceous cement is especially useful for
exterior work because of its insolubility. It may be sawed or cut as
even-course stone or as broken ashlar and used for entire walls or for
trim on buildings made chiefly of brick or other materials. It is also
employed for steps, sills, water tables, coping, pillars, or columns. For
interior use the more attractive types are demanded, particularly the
fine-grained stones adaptable for carving. Sandstone with low absorp-
tive properties is used in lavatories. That which splits readily into thin
slabs is used for floor tile.

Strong sandstones available in large blocks are used in bridge and
dam construction and in sea walls, retaining walls, and dock facings.
Irregular fragments having one good face are used as rubble. Sandstone
is commonly built into attractive masonry walls around cemeteries and
country or suburban estates.

Paving and Curbing. — Sandstone is used quite extensively for street
paving. Only those stones which consist of grains firmly attached to
each other with siliceous cement and which thus approach quartzite in
texture resist abrasion sufficiently to make good paving stones. Some
authorities claim that moderately cemented rock is better than quartzite
for paving because it presents a gritty surface and wears at about the
same rate as the cementing material in the cracks, thus maintaining a
level rather than a smooth, rounded surface. Sandstones that have a
good rift (easy bed splitting) and a good run (a second direction of easy
splitting, perpendicular to the bed) may be trimmed most readily and
therefore are most suitable for paving stones.

SANDSTONE 71

Curbstones may be made of material softer than that used for paving
stones. They are manufactured extensively in conjunction with paving
stones and at quarries where building stone and grindstones are made.
If the rock splits readily, curbing may be split out and hand-trimmed at
the quarry. The more massive sandstones are sawed into curbing.
Production is about five times as great in value as that of paving stones.

Flagging. — A type of sandstone known as ''bluestone" is well-
adapted for flagging or sidewalks because it splits readily into thin,
uniform slabs of large size. Sandstone is also sawed into thin slabs for
sidewalks, but concrete is used for this purpose so universally that
production of flagging is now a very small part of the industry.

Grindstones, Pulpstones, and Other Abrasives. — Only sandstones
having special properties may be used for grindstones. The grains
should be uniform, moderately fine, angular rather than rounded, and
cemented in such manner as to grind steel readily and at the same time
wear rapidly enough to prevent glazing of the surface. At several
quarries, especially in Ohio, grindstones are manufactured in various
sizes up to 7 feet 6 inches in diameter. Many similar stones are manu-
factured to grind pulpwood for making paper. Small pieces of very
fine-grained sandstone are used for making grindstones to sharpen
cutlery and scissors or for making hones, whetstones, and scythestones.

Buhrstone is a type of sandstone particularly adapted for the manu-
facture of millstones. Foreign buhrstone is a hard, tough, porous rock
consisting of silica mixed with calcareous material. American buhrstone
is a quartz conglomerate occurring on the eastern slope of the Appalachian
Mountains, notably in New York, Pennsylvania, and Virginia. The
New York variety, known as "esopus" stone, occurs in a strip about 10
miles long extending southward from High Falls in Ulster County. The
Pennsylvania variety, known as "cocalico" stone, occurs in Lancaster
County. In Virginia similar rock, known as "Brush Mountain" stone
is found near Blacksburg, Montgomery County. Miflstones were used
extensively for grinding equipment 50 years ago, but the industry has
declined greatly, par-tly because of the gradual disappearance of the old
master craftsmen skilled in dressing the stones and partly because of
the development of more efficient methods of grinding grain, paint, and
minerals.

The manufacture of sandstone into abrasive products is a declining
industry. Synthetic abrasives of the aluminum oxide or the silicon
carbide type made in electric furnaces are gradually displacing those
of natural rock origin. Segmental Carborundum pulpstones have lately
come into use.

Miscellaneous Uses. — Sawed slabs of fine-grained sandstone are used
widely for grave vaults. Dense, impervious rock is cut into thin slabs
for constructing laundry tubs and similar plumbing fixtures. Small

THE STONE INDUSTRIES

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amounts are fabricated into electrical switchboards and billiard-table
tops, and line furnaces and acid tanks. Cubical blocks may serve as
footings or underpinnings for posts under heavy structures. Sandstone
is employed for monuments to a very small extent. Highly indurated
quartzite is used for grinding pebbles and for tube and ball-mill linings.

PRODUCTION

The accompanying table, compiled from figures supplied to the
United States Bureau of Mines, shows production by principal uses of
sandstone employed as blocks or slabs.

INDUSTRY BY STATES

Sandstones suitable for commercial use occur in widely distributed
deposits in nearly every State. Those that have been worked for dimen-
sion stone on a fairly extensive scale during recent years are described
by States in alphabetical order.

Arkansas. — Novaculite, a highly siliceous sedimentary rock suitable
for abrasive purposes, is quarried at Hot Springs, Garland County.
The value of the stone depends upon its peculiar texture. It consists of
minute, interpenetrating, sharp-edged crystals with innumerable small
cavities between them — an ideal condition for maximum cutting power.
The rock is used chiefly for the manufacture of oilstones and whetstones.

California. — Sandstones of many varieties occur in more than 20
counties but during recent years production has been confined to only a
few quarries. A massive blue-gray and buff sandstone that has been
used for several notable buildings in San Francisco came from a deposit
extending for 8 miles in the northern part of Colusa County, but there
has been no recent production. A moderately fine-grained arkose
sandstone used more for breakwaters than for buildings is found west
of Chatsworth, Los Angeles County. A deposit of buff sandstone was
worked many years at Graystone, Santa Clara County, and provided
stone for buildings at Stanford University. Brown sandstone occurs
abundantly in Lespe Canyon, Ventura County. Stone for rough
construction is quarried in Santa Barbara County at times. A porous,
argillaceous sandstone merging into shale is quarried near Carmel,
Monterey County. An unusual feature is the presence in some of it of
a high precentage of opaline silica. It is used for building patios and
houses, as garden-wall rock, and for flagstones.

Colorado. — A sandstone that has been quite popular for building
purposes at times is quarried near Turkey Creek, Pueblo County.

Connecticut. — Sandstones of Triassic age occurring in the Con-
necticut River Valley formerly were worked extensively at Portland,
Middlesex County. The well-known "Portland brownstone" was
widely used as building stone in New York, Brooklyn, and other eastern

74 THE STONE INDUSTRIES

cities. The deposit is large, extending from New Haven to northern
Massachusetts, or about 110 miles, with an average width of 20 miles.
At Portland the stone is uniform, medium-grained, and reddish brown
and lies in solid, nearly horizontal beds. Though quite porous, most
Triassic stone is durable if carefully selected and properly used. Com-
plaint has often been made of the spalling of brownstone in buildings, but
deterioration has been due more to faulty construction than to defects
in the stone. Much of it was split into slabs and placed on edge, a posi-
tion which results in more extensive spalling than when blocks are placed
wdth the bedding horizontal. The stone is still quarried and gives excel-
lent service if properly placed in the wall.

Idaho. — Medium-grained light-buff and also fine-grained gray sand-
stones are quarried on Table Rock near Boise in Ada County. They
are used for local building in Boise and are shipped to Colorado, Oregon,
and Washington.

Indiana. — A sandstone quarry has been worked for several years in
northern Orange County, a few miles south of Mitchell. It is reported
that wire saws are used quite successfully in this deposit. Sandstone
for abrasive purposes is quarried at Floyds Knobs, Floyd County.
Orange County was at one time a source of considerable quantities of
whetstones. Building sandstone is quarried also at St. Meinrad, Spencer
County.

Kentucky. — In Kentucky the most important deposits are at Blue-
stone and Farmers, Rowan County, and Wildie, Rockcastle County.
The Rowan County stone is very fine-grained and takes an excellent
sand-rubbed finish. It is sold as sawed and cut stone for building pur-
poses, finer grades being used for mantels and other interior work.
Kentucky and near-by Ohio, especially Cincinnati, are the chief markets,
though some of the stone is shipped to distant cities. The Rockcastle
County stone was used chiefly for trimming, such as sills, caps, and
copings, but quarrying has been discontinued.

Massachusetts. — Triassic sandstone similar to the Portland (Conn.)
stone, ranging from red to brown, has been quarried extensively for
building purposes at East Longmeadow, Hampden County. Although
it is durable if used properly the stone has been in less demand during
recent years.

Michigan. — Grindstones are manufactured at Grind Stone City,
Huron County.

Minnesota. — The most important sandstone-quarrying region in
Minnesota is at Sandstone, Pine County. For many years the Kettle
River quarries at this place have produced an even-grained stone of
light-pink to yellow or brownish-red color. It is probably of Keweena-
wan age. Quartz is the cementing material, and the grains are cemented
so firmly that the rock approaches quartzite in texture. On this account

SANDSTONE 75

it is well-adapted for paving stones for which it is chiefly used. It has
also been employed quite extensively for interior and exterior building,
also as flagging and rubble and to a limited extent for furnace lining.

In southwestern Minnesota the Sioux quartzite of Huronian age is
prominently exposed in Rock, Pipestone, and Nicollet Counties, The
rock is extremely vitrified, having the appearance of massive quartz.
It is red and makes a very beautiful, durable building stone; however, on
account of its extreme hardness it is not used extensively. During
recent years material quarried at Jasper, Rock County, has been used
extensively to line tube mills and as grinding pebbles. For the latter use
it compares favorably in service with Danish flint pebbles.

Associated with the quartzite in Pipestone County is a bed of an
interesting red mineral called "catlinite" or "pipestone." This material
is described more fully on pages 343 and 344.

New Jersey. — Sandstone has been used extensively for bridge con-
struction in New Jersey. Recent production for various building pur-
poses has been confined chiefly to Raven Rock, Hunterdon County,
and Wilburtha, Mercer County. Argillite occurring in Mercer and
Huntingdon Counties has been used for construction of many buildings
in and about Princeton.

New York. — Several types of sandstone occur in New York, The
largest quarries are in the Medina formation, Orleans County. This
stone was formerly used to a considerable extent for building, but the
chief output now is for paving stones and curbing. Both red and gray
stones occur; the former is very attractive for building, and the latter is
best adapted for paving. Because the rock is very resistant to abrasion
it gives good service on streets having heavy traffic. Large quarries are,
or have been, worked at Albion, Holley, Hulberton, Medina, and other
places in Orleans County,

The sandstones most widely used in this State are the so-called
"bluestones" of Devonian age, which occur chiefly along the Hudson
River in Albany, Green, and Ulster Counties and along the Delaware
River in Sullivan, Delaware, and Broome Counties. Other outcrops
are in Wyoming County and in the counties bordering Pennsylvania
westward from Chemung. Typical bluestone is an argillaceous sand-
stone, which is usually dark blue-gray. It occurs mostly in thin beds
and splits readily into smooth, uniform, thin slabs. Thus, it is par-
ticularly useful for flagging, curbs, sills, caps, and steps. The annual
sales value of bluestone for the entire State is about three-quarters of a
million dollars.

Red Potsdam sandstones have been quarried in the northern Adiron-
dacks for building purposes, but none of the quarries are now in operation.
At times small quarries are operated in various parts of the State, mainly
for special jobs, but they are not regular and consistent producers.

THE STONE INDUSTRIES

Ohio. — Just as Indiana is the leading producer of block limestone so
Ohio leads in sandstone, producing between 50 and 60 per cent of the
total output for the United States. Extensive deposits of Mississippian
(lower Carboniferous) age appear in a broad belt which extends from
Portsmouth on the Ohio River in the southern part of the State almost
due north to Norwalk, Huron County, and from there eastward to the
northeastern corner of the State. Except near South Euclid the lower
member, the Bedford stratum, contains little sandstone of commercial
value. The largest quarries in Ohio are in the Berea formation, which

Fig. 12. — A large sandstone quarry near Amherst, Ohio. {Cov/rtesy of The Cleveland

Quarries Company.)

lies above the Bedford. The Cuyahoga formation, which lies above
the Berea and is separated from it by the Sunbury shales, is quarried
in Scioto County, southern Ohio. Pennsylvanian (upper Carboniferous)
sandstones outcrop throughout the eastern third of the State except in
the north, and are quarried in many places. The largest quarries, one
of which is shown in figure 12, are near Amherst, Lorain County,
where the rock lies in horizontal beds which were once the shore cliffs
of Lake Erie. The sandstones are fine- to medium-grained and are blue,
gray, buff, and variegated. Complete oxidation of impurities as a
result of high elevation has given a stable buff coloration to the upper
beds. The rock varies considerably in character from one bed to
another, and each bed may show adaptability for some particular use.
Thus, at different levels stone is obtained for building, for bridge con-

SANDSTONE

struction, for curbing, flagging, and rubble, or for grindstones. The
buff and variegated stones are used both for exterior building and for
interior work in office buildings, churches, and residences. Much of the
building stone is sold in rough or sawed blocks. Differences in texture
have given rise to various local terms. An evenly stratified stone that
splits well is called "split rock"; rock of irregular stratification, marked
by fine transverse and wavy lines, is called "spider web"; and massive

FiG. 13. — An attractive use of sandstone ashlar. {Courtesy of Briar Hill Stone Company.)

stone which shows no evidence of stratification is termed "liver rock."
The Amherst rock contains about 95 per cent silica; the remainder is
made up principally of lime, magnesia, iron oxides, and alumina. To
avoid injury to the stone through freezing of the quarry water, the
quarries are operated only about eight months in the year.

The quarries near Berea, Cuyahoga County, are about 40 feet deep.
The stone is a little darker than the principal products at Amherst and
is adapted chiefly for building, grindstones, curbing, and flagging.
"Euclid bluestone," quarried near Euclid in the same county, is finer-
grained than the Berea stone and must be selected carefully because

78 THE STONE INDUSTRIES

of the common occurrence of pyrite crystals. It is sawed for flagging,
steps, caps, sills, and laundry tubs.

Sandstones from near Empire, Jefferson County, and at Constitu-
tion and Marietta, Washington County, are used chiefly for grindstones
and pulpstones. A fine-grained sandstone from McDermott, not far
from Portsmouth, Scioto County, is quarried for a great variety of uses,
including interior and exterior building, burial vaults, grindstones,
flagging, and many small abrasive stones, such as hones and whetstones.

Sandstone quarried near Killbuck, Holmes County, is widely known
as "Briar Hill" stone and is popular for building purposes on account of
its variegated colors. The quarries are situated at a high level, and the
stone is brought down by cable cars. Production, chiefly of dressed
building stone, has increased greatly during recent years. Its use as
ashlar in home construction is shown in figure 13.

A quarry at Sherrodsville, Carroll County, produces sandstone which
is sold chiefly as sawed and dressed building stone. Sandstone for rough
construction is obtained at Lisbon, Columbiana County, and both
curbstones and rubble are manufactured at Youngstown, Mahoning
County. Other quarry locations are Sugar Grove and East Lancaster,
Fairfield County, and Kipton, Lorain County.

Ohio building sandstone is marketed throughout the Middle West
and even in eastern cities. Most of the other products are distributed
even more widely.

Pennsylvania.— Sandstones are widely distributed in Pennsylvania
and are of many different types. Carboniferous sandstones and quartz-
ites appear in many places. Triassic sandstone quarried at Waltonville,
Dauphin County, was sold in past years as a building stone under the
name " Hummelstown brownstone," but the quarries are now idle. Much
material has been quarried for bridge work and other heavy construction ;
Curwensville (Clearfield County), Koppel (Beaver County) and Ellwood
City (Lawrence County) are noteworthy centers of the most recent
production. Sandstone for rough construction is quarried at Avondale,
Chester County. A very attractive variety for interior and exterior
construction occurs at Waynesburg, Greene County, in the extreme
.southwestern part of the State. Many small quarries produce rubble,
rough building stone, curbing, flagging, and paving blocks. Devonian
bluestones similar to the occurrences in New York are quarried, prin-
cipally along the bluffs of the Delaware and Susquehanna Rivers in
northeastern Pennsylvania. Some of the more important production
centers are Pond Eddy and Kimble, Pike County; Alford and Stevens
Point, Susquehanna County; and Meshoppen, Wyoming County. A
stone ranging from a quartzite to a quartz-sericite schist is quarried near
Edge Hill, Montgomery County, for building stone and as a refractory
for furnace lining.

SANDSTONE 79

South Dakota. — Sandstone for building purposes has been produced
for many years near Hot Springs, Fall River County. The Sioux
quartzite is quarried as building stone near Sioux Falls, Minnehaha
County. The deposit is continuous with that quarried at Jasper, Minn.

Tennessee. — A thin-bedded quartzite occurs near Crab Orchard
and Crossville, Cumberland County. The rock splits into remarkably
uniform slabs ^s inch to 15 inches in thickness and is noteworthy for its
adaptability. The thin slabs may be used for roofing; thicker slabs for
floor tile, flagging, and steps; and the heavier beds, for building stone.
For many years it has been quarried in a small way, but the industry
expanded considerably in 1929 and 1930.

Virginia. — Sandstone of Triassic age was quarried many decades ago
at Aquia Creek, Stafford County. It supplied stone for the United
States Capitol, the White House, Patent Office, and other buildings in
Washington. The quarries were idle for many years but were reopened
and have provided a substantial supply of building stone for use in
Washington and other cities. The rock is light gray, streaked or clouded
with buff, yellow, or red, — combinations that are popular with architects.
Similar rock was quarried many years ago near Manassas, Prince William
County.

Washington. — Sandstone development in Washington has been
confined largely to regions having efficient means of transportation.
Pierce and Thurston Counties have the most available occurrences.
At Wilkeson, Pierce County, a medium-grained gray sandstone is
quarried for local use and for shipment to near-by States. It is sold as
cut stone, sawed stone, rubble, paving blocks, and pulpstones. Stone
which is dark gray at depth and dark or light buff above ground-water
level is quarried at Tenino, Thurston County, and used for building
purposes in Washington, Oregon, Idaho, and California. Abrasive stones
known as ''holystones" are at times manufactured from Tenino sandstone.

West Virginia. — Sandstones are abundant in West Virginia and
represent many geologic formations. A quarry in the Saltsburg sand-
stone at Kingwood, Preston County, has furnished good-quality building
stone for use in New York, Philadelphia, Washington, and other eastern
cities, but very little has been produced since 1914. Grindstones and
pulpstones are produced near Ravenswood, Jackson County, and near
Fairmont, Morgantown, Opekiska, and Uffington, Monongalia County.

Wisconsin. — A belt of Potsdam (Cambrian) sandstone, known as
"Lake Superior brownstone," skirting the southern shore of Lake
Superior has been quarried chiefly at Port Wing, Bayfield County, but
there has been little recent activity. The stone is a coarse-grained,
reddish-brown material that has been used in Wisconsin, in near-by
States, and to some extent in Canada. In the west-central part of the
State, chiefly in Dunn County, a southern belt of the Potsdam sandstone

80 THE STONE INDUSTRIES

also provides commercial stone. Fine-grained cream-colored and buff
stones, marketed under the trade name "Dunville Stone," are used for
exterior building purposes for entire structures or as trimming of schools,
churches, and other public buildings throughout the Middle West and
to some extent in the East. Rock for rough building stone, paving
blocks, curbing, and rubble is quarried in various other parts of the State.

QUARRY METHODS

Influence of Induration. — As previously stated, the workability of
sandstones probably varies more than that of all other common rocks,
owing mainly to the condition of cementation of constituent grains. The
degree of cohesiveness may range from loose and friable types to indurated
quartzites. Quarry methods are governed largely by workability. For
example, highly indurated sandstone can not be channeled but must be
blasted, with the probable result that much of it will be shattered and
wasted, whereas a soft rock may be cut into rectangular blocks with a
channeling machine, and the waste will be much less. Quarry costs per
cubic foot are usually much higher in the harder rocks.

Influence of Rock Structures. — Rock structures that have a pre-
dominating influence on quarry methods are joints, bedding seams, rift,
reeds, and run.

Joints. — Natural open seams or joints presumed to originate mainly
through compressional or torsional earth strains characterize most sand-
stone deposits. In flat-lying deposits they are usually perpendicular to
the bedding and hence are vertical, or nearly so. They generally occur
in two or more systems, the joints of which approximately parallel
each other. When occurring in two vertical systems at right angles
and spaced 10 to 40 feet apart, they greatly facilitate quarrying.

To promote economy, quarry walls are maintained parallel with the
major joint systems. Thus, joints may be utilized to take the place of
openings that must otherwise be made by channeling or blasting.
The term "cutter" is generally applied to closed or inconspicuous joints,
sometimes called "blind seams" or "closed seams." Usually they are
planes of weakness that must be avoided in dimension stone.

Bedding Seams. — Open seams parallel with the bedding occur com-
monly in sandstones and usually are of great advantage in quarrying.
If they are present at intervals of a few inches to 3 feet apart, the deposit
is described as "thin-bedded"; if at intervals of 10 or 15 feet, it is "thick-
bedded " ; rock in massive form with no open bed seams is " tight-bedded."
Deposits near Amherst, Ohio, are of the latter type.

Most sandstone quarries are situated in horizontally bedded deposits.
Such flat-lying beds afford the simplest type of quarrying. The Potsdam
sandstone of northern New York is an exception, as the beds dip 20 to 25
degrees, but very little quarrying is now carried on in this rock.

SANDSTONE 81

Rift. — Rift is the plane of easiest splitting in sandstone; almost with-
out exception it parallels the bedding. It is a variable property; some
beds split with the utmost ease, whereas others have so poor a rift that
the rock splits in other directions almost as easily as it does parallel with
the bed. Such rocks are said to be lacking in rift. Rift is due chiefly to
orientation of grains. The presence of flaky minerals like mica or clay
may increase the rift, for in the process of sandstone deposition such
grains tend to come to rest horizontally, parallel with the bedding. In
like manner, other mineral grains tend to have their long axes parallel
the bedding plane, and this parallelism increases to a marked degree
the ease of splitting.

Rift may vary greatly in successive beds of a deposit. In the Amherst
(Ohio) quarries the "split-rock" beds have excellent rift, which gives
smooth uniform surfaces. In "cross-grained" beds the rift is diflficult
and uncertain; it may slant at abrupt angles to the general bedding plane.
The "liver rock" has a massive structure with no indication of bedding
and consequently lacks rift.

In quarrying, a good rift assists greatly as it facilitates bed lifting
where open bed planes are absent. Ease of splitting and the smooth
surfaces obtained are also of great advantage in subsequent operations of
shaping blocks into various finished products in the mill or yard.

Reeds. — The rift may not be the same in all parts of the same bed;
that is, the rock may split much more easily along certain planes than
along others. This may be due to a change in sedimentation, such as the
deposition of a thin layer of foreign material, as clay, to which the sand
grains above and below do not adhere readily. Again, it may be due to a
pause in the process of deposition with a smoothing over of the surface
and a filling up of the irregularities that are essential to a condition
of relatively high cohesion perpendicular to the bedding plane. It may
also be due to parallelism of grain orientation in certain zones. Such
planes, along which the rock tends to split with greater ease than in inter-
mediate planes, are termed "reeds." They are characteristic of many
bluestone deposits. The quartzites near White Haven (Pa.) split easily
along reeds marked by fine white lines and with difficulty in intermediate
positions. Like rift, the reeds are very helpful in separation of blocks.

Run. — The term "run" is applied to a second direction of easy split-
ting less pronounced than rift. It is also called the "breaking way" or
"grain," though the term "grain" is used by some quarrymen as a
synonym for rift. Usually the direction of run is perpendicular to the
rift, and therefore in flat-lying beds the run is in some vertical plane,
since the rift is horizontal. Bownocker^" states that from Berea to Berlin
Heights, Ohio, the run is nearly east and west — that is, it parallels the

1" Bownocker, J. A., Building Stones of Ohio. Geol. Survey of Ohio, ser. 4, Bull.
18, 1915, p. 111.

82 THE STONE INDUSTRIES

old shore line. Run is probably due to orientation of minerals and in
the above locality prevailing ocean currents at the time of deposition
may have arranged the minerals with their long axes parallel to a particu-
lar direction of the compass. In some sandstone deposits a distinct run
is recognizable and is of considerable advantage in giving smooth,
straight, broken surfaces or in permitting wide spacing of drill holes
for blasting or wedging. In other deposits it is absent or is so indefinite
that it exerts no apparent influence on quarry processes.

Quarry Methods in the Softer Sandstones. — By far the larger part of
the sandstone produced in the United States is from the softer types of
moderately easy workability. Channeling machines may be employed
in such stone, the extent of their use depending mainly on joint
systems. Where few joints are found it may be necessary to channel
all wall cuts and whatever other cuts may be required for separating
the larger masses of rock, except where an occasional joint may be utilized.
The larger quarries in northern Ohio are of this type. If joints are in one
parallel series, spaced 20 to 50 feet apart, it may be necessary to channel
wall cuts only along the side at right angles to the joints. These are
called "back-wall cuts." Where joints are in two intersecting systems,
meeting approximately at right angles, channeling may be required only
for the removal of key blocks. In deposits where joints are more
closely spaced, channeling machines may not be required, the
necessary breaks being made by blasting or wedging. An effort is always
made to work into such deposits in the direction of convergence of the
joints in order that blocks may be removed without binding against
walls. Sandstone deposits near Springfield, Mass., and Hummelstown,
Pa., are of this type. Wire saws, described in a later chapter on slate,
are used to a limited extent as substitutes for channeling machines.

Quarry methods are influenced greatly by the nature of the bedding.
In massive, tight-bedded deposits floor breaks must be made by wedging,
and in heavy-bedded deposits like those at Berea, Ohio, large masses are
channeled and subsequent breaks made with black-powder shots. Cham
neling usually is required only for wall cuts in thin-bedded deposits, and
wedging generally is better than blasting for further subdivision because
straighter breaks may be made and less waste results. Deposits of this
kind occur near South Euclid, Ohio, and Farmer, Ky. A good rift
greatly assists quarrying and is especially advantageous in tight-bedded
deposits where floor breaks are required. If the rift is good, a mass of
stone 12 to 15 feet wide may be lifted by wedging, whereas, in a "liver
rock," beds are rarely lifted in widths of more than 5 or 6 feet.

Quarry Methods in Indurated Sandstones. — As a rule, sandstones
sufficiently indurated for good paving blocks are too hard to be channeled
economically, and blasting or wedging must be substituted. Quarrying
in such deposits is therefore more complex and costly than in the softer

SANDSTONE 83

types. Even in some hard rocks channeling machines are used for wall
cuts because much shattering results from blasting if only two free
vertical faces are present. In best practice, quarry walls are maintained
parallel with the major open joints, which are utilized wherever possible
instead of channel cuts. Larger masses are subdivided by separating
along bed planes and making cross breaks by wedging in drill holes in
directions of rift and run, if such are present. Easy splitting of beds and
conveniently spaced vertical open joints are favorable structural features.

QUARRY PROCESSES

Channeling. Rate of Cutting. — When sandstone was first quarried in
the United States channels were cut with hand picks wide enough to
admit the body of a workman. About 1880 this slow, wasteful method
was superseded by steam-driven channeling machines capable of making
cuts 6 inches wide or less. Channeling machines of the steam, electric,
and electric-air types similar to those described in the preceding chapter
on limestone are now widely used. The rate of cutting depends on the
condition of cementation of the rock and ranges from 100 to 500 square
feet a day. If hard, flinty masses are encountered the rate will be
diminished temporarily, and the channel cut may be diverted from its
straight course. Usually the average rate of cutting is much less than the
maximum rate of which the machine is capable, because heavy blows
struck by channel bars when a machine is driven at its maximum capacity
tend to shatter or "stun" the rock. "Stunning" is a quarryman's term
for the production of impact fractures that may extend a foot or
more into the rock and thus waste otherwise good stone.

In terminating a channel cut in solid rock the cutting out of the lower
corner to give a vertical end is slow and tedious, but sometimes is greatly
facilitated by sinking a 4-inch vertical drill hole at the place where the
cut is to end.

Wear on Steel. — Channeling in sandstone is quite different from that
in limestone or marble. Although the rate of cutting may be much
faster the steel wears much more rapidly on account of the abrasiveness
of the sand grains. In the quarries of northern Ohio the machine usually
works back and forth on a cut about 30 feet long, and for such a cut the
steel must be changed about every 18 inches of depth attained because
of the loss in gage from wear. The first set of bars makes a cut about
4 inches wide, and each successive set must be narrower than the preced-
ing to avoid binding. Until recently cutting was done dry as the steel
wears more rapidly if water is added. One or two men were employed
at each machine to scoop out the sand cuttings, which in soft sandstone
amounted to several tons a day. Wet methods are now used.

Maintaining Minimum Number of Channel Cuts. — Channeling is more
expensive than blasting or wedging per square foot of surface obtained

THE STONE INDUSTRIES

and therefore is employed only for wall cuts, for separation of key blocks,
and for whatever other cuts may be necessary to prepare a block or mass
of stone for wedging or blasting. The latter processes are very ineffective
or wasteful unless the mass to be separated has five free faces, leaving
only one to be broken free. Thus, the mass of stone shown in figure 14
had only four free faces before channel cut "x" was made, namely, the
two sides, front, and top, and therefore, it could not be wedged or blasted
effectively. After cut ''x" is made it is fast at the floor only and there-
fore has five free faces. A floor break, "a," may be easily made by
wedging, and the block may be subdivided further by wedging or blasting

at "b." For this and each sub-
sequent break there will always
be five free faces. Quarrying
should be so planned that the
least possible channeling may be
done to attain favorable wedging
or blasting conditions. Vertical
joints may be of great assistance
Fig. 14. — Separating blocks with five free in obtaining the necessary num-

faces. X, channel cut providing fifth free , £ r £ ta • i -u

face; a, first break; b, second break. bcr of free faces. It IS also ob-

vious that open bedding planes or
a good rift will reduce the number of channel cuts.

Direction and Spacing of Cuts. — Channel cuts should parallel or be
at right angles to the major jointing systems. The spacing of channel
cuts should be governed by the size of quarry block desired; that is, the
number of feet between cuts should be multiples of the final quarry-
block dimensions.

Drilling. Machinery. — Tripod drills, bar drills, and hammer drills
are the chief types used. The first is a reciprocating drill mounted on a
tripod, and the second is a similar drill attached to a horizontal bar
supported by four legs. The tripod must be moved to a new position
for each hole drilled, but a line of holes may be drilled from one position
of the bar, the drill being moved along and clamped successively in new
positions. Bar and tripod drills usually are operated by steam. A
hammer drill is a nonreciprocating impact drill with an automatic rotat-
ing device. It employs hollow-steel drill bits through which the exhaust
air passes and blows the cuttings from the hole. It is usually unmounted,
is held in position by a handle bar, and may be moved with very little
loss of time. This offers certain advantages, particularly in thin-
bedded rock where holes are shallow and frequent moves are
necessary.

Compressed air generally is preferred to steam for quarry drilling,
particularly in cold climates where the condensation loss of steam is
heavy. Moreover, when steam drills are used water must be supplied

SANDSTONE 85

to remove the cuttings, which necessitates extra labor and makes a wet
or muddy floor.

Drill Steel. — Drill steel should be of a consistency that will withstand
excessive abrasion. Efficiency in drilling depends largely on the shape
of the bit. As narrow wings wear away quickly the drill head is shaped
to keep as much steel as possible near the circumference of the bit.
Most sandstones cut rapidly, therefore drill bits must have grooves large
enough to provide easy clearance for cuttings. Some drillers prefer
square bushings to hexagonal, as they do not wear off so quickly.

Rate of Drilling. — The rate of drilling varies with the hardness of the
stone; 1 foot in 38 seconds for a l^:4-inch hole has been recorded in a
northern Ohio quarry. Holes of )^ inch diameter were drilled in White
Haven (Pa.) quartzite at a rate of 3 inches in 35 seconds, a much slower
rate for holes of very small diameter.

Circle-cutting Drill. — In some localities where grindstones or pulp-
stones are made, rectangular blocks are scabbled to a circular shape.
In southeastern Ohio it has been found more convenient and less wasteful
to cut out circular blocks in the quarry with a machine known as a
"ditcher" or "circle-cutting drill," which is supported by tripod legs and
a vertical bar which fits into a 4- by 4-inch square hole in the surface of the
rock. The drill is attached to one end of a heavy crossbar, with a
counterbalance weight at the other end, and is rotated by a worm gear.
By securing the drill in different positions on the bar the diameter of the
circle to be cut may be varied. In cutting a circle 7 feet in diameter the
steel is changed about every 6 inches in depth, and each successive drill
bit is about one-fourth inch smaller to allow for loss in gage by wear. A
four-pointed star-shaped drill head is used. If cuts run from their true
course, as, for example, at the point where they meet other cuts, a
sharp-pointed bar is used to trim and straighten them. It is claimed that
a ditcher will cut as many square feet in a day as a channeling machine,
and much less time is required to set it up, as no tracks are necessary.

When a circular cut is completed a drill hole for the floor break is
made by means of an air drill which slides on a horizontal bed. The
drill is held in proper position and advanced by means of a hinged handle
and crossbar.

Blasting. Explosives. — Black powder is used almost invariably for
blasting dimension sandstone because dynamite unless of very low grade,
gives a sudden and violent explosion, thus shattering the rock too
greatly. Just enough powder should be used to make the fracture, and
no more.

Knox System of Blasting. — The Knox system has two essential fea-
tures— a grooved drill hole and an air space above the charge. Holes
are drilled nearly to the bottom of beds and reamed or grooved with a
flanged tool driven into the hole by sledging or operated as a drill bit

THE STONE INDUSTRIES

with the rotating device of the drill thrown out of gear. The grooves,
about one-fourth inch in depth and on opposite sides of the drill hole, are
made exactly in line with the direction along which the break is to be
made. A small charge of black blasting powder is added, and a plug
of cotton waste or other suitable material is placed in the hole some
distance above the charge. The hole above the plug is filled with sand
or other stemming. When an air space is thus provided the force of an
explosion is exerted over a relatively wide surface and causes less shat-
tering of rock than when the intensity of the force is localized in one
spot. Moreover, the explosive force, as it enters the grooves formed by
the reamer, tends to give ^ straight break. In the heavy-bedded rock

Fig. 15. — Uneven sandstone surface resulting from a break oblique lo the "run.'

near Berea, Ohio, the system is modified by leaving air spaces above and
below the charge.

Methods of Shot Firing. — For single shots either a fuse or an electric
firing machine may be used. Where a number of drill holes are to be
fired at once electric firing is necessary and may be done with a hand-
operated machine or by connection with the quarry current.

Arrangement of Drill Holes. — Holes for bed-lifting are drilled in line
with the bedding planes or rift. If the rock has a pronounced "run,"
as described earlier, vertical breaks are, in best practice, made in line
with it. If breaks are made oblique to the run two disadvantages are
entailed. First, the rock splits with greater difficulty, and holes must
be closely spaced ; and second, a very uneven surface is obtained. Figures
15 and 16 illustrate the contrast in surfaces obtained in making breaks
obhque to the run and parallel with it.

SANDSTONE

blasting for Subdivision of Larger Blocks. — The preceding discussion
of channeling and blasting relates almost entirely to- separation of larger

Fig. 16. — Smooth sandstone surface resulting from a break parallel to the "run."

rock masses from solid ledges. These masses usually are subdivided by
blasting in heavy-bedded rock and by wedging in thin beds. It is a
generally recognized principle that the blast should be centered; that is,
an equal mass of rock should be on each side of the line of fracture. If
drill holes are so placed that the rock
mass is not balanced properly, the
break tends to run toward the lighter
mass. Therefore, the process of sepa-
ration is a halving of the masses suc-
cessively until blocks of the desired
dimensions are obtained.

The procedure in an Ohio quarry
illustrates a typical process of sub-
division. As shown in figure 17, the
primary masses are 44 by 26 feet.
Fractures made by blasting are shown
by small letters. The shots are dis-
charged in order of lettering, a, h, c,
d, e. The final subdivisions give a
series of blocks 63-^ by 5,i^ feet, a size
most convenient for curbing and flagging. This indicates the foresight
necessary in selecting for the larger masses dimensions suitable for eco-
nomical subdivision.

In rock with a pronounced run most subdivisions may be made by
blasts in single, centrally located, drill holes. If the break is inclined

<— -26-— -*

-«.

Key Blocks

Fig. 17. — Method of subdividing
blocks in an Ohio sandstone quarry.
Breaks are made in the order of lettering,
a, h, c, d, e.

88 THE STONE INDUSTRIES

to the run, or if the run is poor, more than one blast hole may be required.
Shots in single holes are commonly used for breaks up to 15 or 20 feet
long. If the mass to be separated is more than twice as long as it is
wide it is advisable to use at least two holes, which should be so arranged
that the center space is a little more than twice as long as the end spaces.
If the mass to be broken off is a small part of a much larger mass, the
break tends to curve at the ends and slant toward the lighter part. This
tendency may be overcome in some measure by blasting in two drill
holes with a relatively long center space between.

Wedging. Operations in Which Wedging Is Employed. — Bed-lifting
and subsequent separation of blocks on the bed or rift are accom-
plished almost exclusively by wedging. Vertical breaks are made by
wedging, except in heavy-bedded rock, where blasting usually is
employed.

Type of Wedge Employed. — For wedging in drill holes quarrymen use
the " plug-and-feather" type of wedge described in the chapter on
limestone. Wedges are of different lengths to accommodate them for
use in deep or shallow holes. Blunt-steel wedges used without feathers
are employed for driving in notches. A small steel wedge that tapers
to a thin edge is known as a "point." This term is applied also to a
tool having a pyramidal point used in finishing the surface of stone.
A short, blunt wedge with a rectangular sledging face and triangular
cross section is known as a "bull wedge."

Use of Wedges in Bed-lifting. — In tight-bedded deposits, when by
means of channel cuts or open joints four free vertical faces are provided
for a large mass of stone, the next step is to free this mass from the quarry
floor. As the bedding in most sandstone quarries is horizontal, this
process of separation is known as "bed-lifting," and the breaks are called
"floor breaks." Wedges are used very generally for bed lifting. Ease
of splitting depends on the rift, but breaks are so easily made in almost
any sandstone that drill holes are unnecessary. In their place notches
are cut into the face of the rock by means of hand picks. The notch is
known locally as a "grip" or "side shear." Its lower face is horizontal
or has a slight upward slant; and the upper face slants sharply downward,
forming a V-shaped cut several inches deep. A sharp steel pick is used
to finish the grip to bring it to a sharp point; otherwise, the end of the
wedge would strike against the solid rock and fail to exert the desired
effective upward and downward pressure. Blunt wedges are placed in
the grip and driven with sledges. In hard-splitting rock or in making an
excessively wide break wedges may be placed almost touching each
other. Occasionally grips are cut on two faces, and the mass is raised
by simultaneous wedging at the side and end.

In making floor breaks for large, circular masses cut out for grind-
stones, wedging in a grip is supplemented by wedging in a single drill

SANDSTONE 89

hole 4 or 5 feet deep passing under the center of the stone. A long
wedge with feathers attached to its extremity is inserted in a drill hole.
When it is driven between the feathers the lifting force is exerted near the
bottom of the hole.

Wedging for Subsequent Breaks on Bed. — The softer sandstone blocks
may be split on the bed by cutting grip holes and driving points in them.
In easy-splitting rock they may be placed 1 to 2 feet apart; in tougher
rock they may be placed close together in a continuous grip.

In the more indurated sandstones pick holes can not be cut readily.
In some quarries it is customary to place a block on edge and split it by
sledging on a ''sett" — a quarryman's term for a square-faced steel tool
held in position by means of a handle. The block is marked at the ends
and struck successive blows along the line of desired splitting until a
fracture is made. Quartzites are usually split by wedging in shallow drill
holes.

Wedging for Vertical Breaks. — In quarries which have open bedding
planes spaced at distances of 5 feet or less, wedging may be largely
substituted for channeling, channel cuts being made only where clearance
is required. If possible, such breaks should be made parallel with the
run of the rock. In some northern Ohio sandstone quarries for making a
cross break in a mass of stone 4 to 5 feet thick quarrymen first drill a
row of holes 18 inches apart. Every third hole is made 4 feet deep and
larger than the others, which are 2 feet deep. Plug-and-feather wedges
are placed in the holes and sledged in succession, beginning at one end
of the line, one blow being given to each of the smaller and two blows to
each of the larger ones. Sledging is continued back and forth along the
line until a fracture appears. Breaks thus made may be 80 or 100 feet
long and 20 to 40 feet back from the face. For thin beds, shallow holes
are adequate.

In heavy beds with a poor run, deep-hole wedging is employed.
Thus, for a bed 5 feet thick holes may be made 43^ feet deep and 1}^ to
23^^ feet apart. Holes of this depth are usually about 1% inches in
diameter at the top and 1 % inches at the bottom and are drilled exactly
in the same plane. To assist in producing a straight break in tough rock
a channel about 2 inches deep is cut with hand picks across the rock
surface in line with the drill holes. Occasionally the holes are reamed,
as in the Knox system of blasting. For deep-hole wedging the long
plugs and feathers used are so constructed that when the plug or wedge
is driven the feathers are forced apart a uniform distance at all points
from top to bottom. Thus the pressure is uniformly distributed through-
out the full length of the wedge and is much more effective than when
exerted at a single point or over only a small part of the drill-hole wall.
Furthermore, a wedge with a long taper exerts great force without heavy
sledging.

THE STONE INDUSTRIES

As soon as a fracture appears chips are broken out midway between
drill holes, and blunt wedges are inserted. By sledging these wedges the
pressure is relieved from the plugs and feathers, and they are removed.
If the mass is not too heavy it may then be moved by steel bars which are
inserted in the drill holes as levers.

In rock with a good run breaks up to 3 feet in thickness may be made
in beds merely by driving points in a row of holes cut with hand picks.
Even in tough rock small breaks may be made by cutting a continuous
grip and driving wedges placed close together.

To assist in making straight breaks wedging is sometimes employed
in conjunction with blasting. A powder charge is placed in a reamed

Fig. 18. — Arrangement of derricks for hoisting blocks from an Ohio sandstone quarry.

hole in the center of a mass of stone. Two wedge holes are drilled, one on
each side of the blast hole midway between it and the edge of the block.
Plug-and-feather wedges are driven into them until considerable strain is
placed on the rock before the shot is fired.

Hoisting. Equipment Used. — Most hoisting at sandstone quarries is
done with derricks consisting of a mast and swinging boom. Portable
types are used for wide and shallow quarries where frequent moves must
be made. A type of stiff-leg derrick used near McDermott, Ohio, may be
moved to a new position in about two hours. When placed in position
the base is loaded with blocks of stone to give it stability. For light
hoisting a power shovel having a boom equipped with a running cable
may be substituted for a derrick. Thus, power shovels which are used

SANDSTONE 91

for stripping operations in the winter and would otherwise be idle all
summer are put to practical use.

Position of Derrick. — For large, deep quarries, such as those near
Amherst, Ohio, many derricks arranged at regular intervals along the
quarry bank are required. The mass of rock worked out from one
position of a derrick is called a "motion." This includes the area covered
by the radius of the boom together with that from which the rock may be
dragged economically. The average area of a motion in one Ohio quarry
is 134 by 61 feet. Figure 18 illustrates a ledge or bench and the series of
derricks used to hoist the stone from it.

Cable Attachment. — Grab hooks, chains, and cable slings are used to
hoist quarry blocks from the pit to the bank. Grab hooks are more
generally used, for they have an advantage over other methods in that a
block may be lifted from a flat position on a quarry floor, whereas
chains or slings necessitate raising it several inches from the floor and
blocking it up in order that the lifting apparatus may be passed beneath
it. Shallow holes are made for the tips of the hooks. For hoisting heavy
blocks two pairs of grab hooks may be used, one being attached near each
end of the block. Some companies prefer chains or slings, as they are
considered more secure than grab hooks. They may be left around
blocks which are hoisted from a quarry and placed on flat cars for trans-
portation to mill or yard. It is then a simple matter to hook into the
chain for unloading, and much time is saved.

Pumping. — Some quarries of the hillside or shelf type are fortunate
enough to have automatic drainage. Even pit quarries may in
exceptional instances be underlain by permeable beds which permit
water to drain away. In those that do not have automatic drainage,
pumps must be installed. If only surface water enters a quarry little
pumping is necessary, except in times of heavy rain or flood, but if
springs are encountered the water has to be removed almost constantly.
For shallow quarries with a drainage basin lower than the floor a siphon
may be used if the lift is less than 30 feet. This method has been
used at Hummelstown, Pa., and in a number of bluestone quarries.
Piston pumps operated by steam, electricity, or gasoline engines, cen-
trifugal pumps, and pulsometers are the types most generally used.

YARD SERVICE

Yard service relates to transportation from quarry banks to mills or
finishing plants or direct to transportation lines where mills are not
operated. It also includes transportation of finished mill products to
railway lines or navigable waters over which they are carried to their
destination.

If mills are close to quarries a yard derrick may take stone from the
quarry bank and deliver it direct to the mill. If mills are at a distance

92 THE STONE INDUSTRIES

blocks are loaded onto cars for transportation. When finishing processes,
such as shaping grindstones or splitting and trimming curbstones, are
conducted outdoors, yard derricks may be employed to handle heavy
rock masses. They are also used to load gang cars, to pile finished
products in the yard, or to load them ready for transportation. A derrick
with a boom which may be swung in a complete circle around the mast
but can not be raised or lowered is convenient for handling material of
small size. The boom is in the form of an I-beam, and a small traveling
crane runs back and forth on it. In some places, locomotive cranes do
the work of derricks. Overhead traveling cranes that are commonly used
in mills may be extended to give yard service.

Transportation of rock from quarries to mills or from mills to shipping
points may require cars and trackage. Haulage may be by gravity or
by locomotives, cables, horses, or mules. Teams and wagons or auto
trucks are also used.

SANDSTONE SAWMILLS AND FINISHING PLANTS

Mills Connected with Quarries. — Although large quantities of sand-
stone are sold to dealers or finishing plants nearly all quarries that
produce building stone, grindstones, curbing, or flagging, except blue-
stone quarries, also operate mills or finishing plants. This association of
activities has certain advantages. For instance transportation expense
of waste rock is avoided, as it is left near the quarry; also the quarryman
understands his rock and can work it most economically.

Mills usually are close to quarries. Even when quarries are at high
levels — for example, those near Empire, Ohio — mills are at the same level,
and finished products are brought down by cable cars. At Sherrodsville,
Ohio, however, the quarry is at a high level, and the finishing plant is at
the foot of the hill.

Sawing. Gang Saws. — Sandstone is sawed mostly with gang saws —
iron blades set in a frame. Sand and water are fed to them as they
travel backward and forward, and they cut by abrasion. Blocks of any
width or slabs of any thickness may be obtained by merely adjusting the
spaces between the blades. The frames are of various widths and lengths,
depending on the sizes of blocks sawed.

Two types of gangs are in common use — the rope feed and the screw
feed. The rope-feed gang is suspended by a steel cable attached to
counterbalance weights. The weights may be so adjusted that the
gangs can exert any desired downward pressure of the saws on the rock.
Thus, constant pressure may be maintained, and the rate of cutting will
be governed by the hardness of the rock. If a hard, flinty mass is
encountered, the rate of descent is reduced automatically until the
obstruction is cut through.

SANDSTONE 93

Screw-feed gangs are fed downward by gears, and although the rate of
downward motion may be regulated, the device is not self-adjusting. If a
flinty mass is encountered the rate of sawing is not automatically reduced,
and if the saw is overcrowded the blade is inclined to run to one side, with
consequent production of an uneven rock surface. The screw feed is
employed on nearly all modern gangs.

The saw blades are carefully adjusted to run straight and true without
any side motion, which may involve adjustment of shafts and bearings,
as well as of the blades themselves.

Abrasives. — Silica sand is the abrasive used most commonly in sawing.
It leaves a smooth surface and causes no staining of the rock. Although
crushed steel and steel shot cut 25 to 50 per cent faster than sand under
similar circumstances, they have some disadvantages. They leave a
much rougher surface, and if the stone is to be used for structural pur-
poses, sand-rubbing of the surface may be required, whereas if sand alone
is used as abrasive this process may be omitted. If the stone is porous,
stains may result from iron rust. Steel abrasive is satisfactory if the
stone is to be used for curbing or flagging, as slight stains have
little consequence. A mixture of sand and steel sometimes is used.

Sand Pumps. — Centrifugal sand pumps are commonly used for
elevating the abrasive to a point above the gangs from which it may be
distributed to the saws for repeated use. A belt with crossbars may be
used to convey the sand to the pump well if the concrete bed beneath the
gangs is too flat to return it automatically. In many mills an air lift is
used. A well deep enough to have about one and a half times as much
pipe submerged as above water level is required. A jet of compressed
air entering at the bottom agitates and aerates the water, causing it to
rise in the pipe and carry the sand with it. The great advantages of an
air lift are its simplicity and the absence of moving or rotating parts,
which are rapidly worn out by sand. At some mills pumps are not
employed, the abrasive being shoveled by hand. Where river sand is
obtainable near by, it may be allowed to escape after one use.

Rate of Sawing. — The rate of sawing sandstone blocks depends on a
number of factors, such as length and number of blades, kind of abrasive
and hardness of the stone. Gangs containing 10 to 15 blades saw average
sandstone blocks 5 to 7 feet long at the rate of 3 to 8 inches an hour when
sand is used, and 6 to 12 inches when steel is used. The rate also is
governed by the nature of the product. For rough material, such as
curbing, saws may be crowded to their maximum capacity, but when
building blocks are being sawed this is not permissible, as it may produce
irregularities on the surface. The more indurated sandstones can not be
sawed profitably.

Gang Cars. — In old-fashioned mills timber beds were provided on
which blocks were placed for sawing. The difficulty encountered and the

THE STONE INDUSTRIES

excessive time spent in loading and unloading the bed led to introduction
of the gang car, which is simply a portable saw bed — a small four-wheeled
car which runs on a track beneath the gang and is braced securely.

Transfer Cars. — In some mills much loss of time occurs in removing
sawed slabs from gang cars and reloading them with blocks ready for
sawing. To reduce the time in which the gang saw is idle the more
modern mills are equipped with "transfer cars" which run on a depressed
track in front of the gangs and are provided with a short section of track
across the top. Thus, a gang car may be run from beneath a gang saw
onto the top of a transfer car and removed very quickly. Another gang
car loaded with a block of stone is held ready on a second transfer car,
which may be shifted quickly into proper position in front of the gang-car
tracks, and a new block is thus placed beneath the saws with little loss of

~ b

•)

: :

b :

: :

: -

Fig.

19. — Arrangement of transfer and gang-car tracks in a sandstone sawing mill,
gang saws; h, gang-car tracks; c, depressed transfer-car track; d, transfer car.

time. The track arrangement is shown in figure 19. At some mills
gang cars are readily loaded and unloaded by derricks or overhead
traveling cranes, and transfer cars are not used.

Other Types of Saws. — While gang saws generally are used for major
cuts, smaller blocks and slabs are usually shaped with other types of
saws. Circular saws with Carborundum teeth have given satisfac-
tory service, even in hard sandstones. Blades mounted with diamond
teeth and set in straightcut gang frames are used to some extent. Dia-
mond circular saws have not given satisfactory service.

Wire saws are used for jointing sandstone mill blocks at McDermott,
Ohio. Blocks are placed on the saw bed in piles about 10 feet wide and 4
to 12 inches high, and thus 12, or more are cut at one time. Sand is
used as abrasive. The saw cuts downward by automatic feed at about
24 inches an hour. It cuts very effectively and to reasonably accurate
dimensions with a tolerance of about one-eighth inch. Wire saws also

SANDSTONE 95

are used very effectively in northern Ohio sandstone mills. Clever
adaptations have been devised for cutting rough columns and even for
blocking out carved work.

Rubbing. Nature of Process. — Rubbing is the process of smoothing
the surface of stone by abrasion. Exposed surfaces of structural blocks
usually require such treatment. Where sand is used as the abrasive in
sawing the resulting surface may be so smooth that rubbing will be
unnecessary. However, where steel is used the surface usually is
scratched and scored to the extent that rubbing is required.

Rubbing Beds. — A rubbing bed consists of a heavy iron disk 10 or 12
feet in diameter, which rotates in a horizontal plane. A block or slab of
stone that requires rubbing is placed on the upper flat surface, and while
the disk rotates the block is prevented from rotating with it. Sand
and water are supplied, and the surface is rubbed or ground to desired
smoothness and uniformity. Rubbing beds also are used for grinding
blocks or slabs to accurate dimensions.

Reuse of Sand. — At some mills sand once supplied to rubbing beds is
carried away without being reused. A more economical method is to
return it to the bed until it is worn out. To accomplish this purpose
the sand is washed to a sink in which the larger particles remain while
the fines are carried away in the water. A bucket elevator or some other
device is used to carry the sand to a point above the rubbing bed.

Planing. — Planers, chiefly of the Scottish reversible-head type, are
used in shaping such forms as cornices, moldings, and curbstones. In
planing the harder sandstones difficulty is experienced in getting a tool
that will stand the work required of it, as the heat generated burns the
steel. Overheating may be overcome by directing a heavy stream of
water on the tool.

Manufacture of Curbing. — The manufacture of curbstones is an
important part of the sandstone industry. The larger blocks usually are
drilled and split into smaller sizes with plug-and-feather wedges. Final
splitting into rough curbstones is accomplished in different ways, depend-
ing upon the ease of splitting. In "split rock" a series of notches are
cut in line by means of a pick, the rock is then marked along the line
with a chisel-edged tool and hammer, and the split is made by sledging
bull wedges in the notches. In rock which splits with greater difficulty
plugs and feathers may be used. Massive rock is sawed into curbing
blocks.

Some Ohio mills are designed especially for manufacture of curbing.
Planers are arranged in two parallel series with tracks between. The
sandstone blocks are brought in on cars and transferred to the planers
with overhead traveling cranes or pneumatic hoists. Finished curb-
stones are reloaded in the same way and conveyed from the mill for
storage or shipment.

THE STONE INDUSTRIES

Manufacture of Grindstones and Pulpstones. — In southern Ohio
the larger grindstones and pulpstones are cut in circular form in the
quarry by means of circle-cutting drills, as described on a previous page.
In northern Ohio they are quarried as rectangular blocks and scabbled
to circular form. Stones thus roughly shaped are finished by cutting
square-center holes, placing them on shafts, and turning them to true
form with steel tools as they rotate. Both faces and sides are trimmed
in this way. Figure 20 illustrates the method of shaping a 7-foot stone.
The upright pins on the timber base are for the purpose of holding the
cutting bar in various positions. A workman may stand on either side,
and if two men are employed both sides of the stone may be trimmed

Fig. 20. — Method of shaping a large grindstone in a lathe.

simultaneously. Grindstone lathes are operated by steam, electricity,
gasoline, or natural-gas engines, the choice of power depending upon
relative costs and availability. Most lathes are provided with suction
pipes in the pits to carry away the dust and thus reduce the danger of its
injurious effects upon workmen.

Smaller stones which are not circular are mounted in lathes and
marked at each side for their proper circumference by holding pointed
tools against them. The grooves are not cut deeply into the rock as
this would involve the danger of masses of rock flying from the stones,
impelled by centrifugal force. While the stones are at rest the outer
masses are broken off with hammers and thereafter the stones are turned
to finished form in the usual way.

Cutting and Carving. — A certain amount of hand cutting is necessary,
especially in plants where building stone is produced. It involves

SANDSTONE 97

rough work, such as the cutting of rock-face ashlar from irregular waste
blocks, and also the finer carving required for decorative effects. Sand-
stones are so variable in character that both methods and tools differ
widely in various localities. For example, a light and springy tool
"plucks" less than a heavy tool in the fine-grained sandstones of McDer-
mott, Ohio. The best methods of cutting and the most efficient tools
to use can be determined only by experience.

Handling of Material. — Stone is a heavy material, and speed in mill
work demands the most efficient types of crane service. Derricks are
sometimes employed, but the overhead traveling crane is handled
more quickly and easily and has a wider range. Pneumatic cranes give
very efficient service for handling the smaller pieces, such as curbstones.
In some Ohio curbing mills a pneumatic crane of 2,000-pound capacity
serves each planer, and other cranes are employed for yard service.

THE BLUESTONE INDUSTRY

Definition of Bluestone. — Bluestone is a commercial name for a
variety of sandstone having properties sufficiently characteristic and
distinctive to justify its recognition as a separate rock type. It may be
defined briefly as an indurated arkose sandstone, most of which splits
easily into thin, smooth slabs. The term was first applied to certain
blue sandstones quarried in Ulster County, N. Y. With the develop-
ment of the industry it was found that stone of similar character was
abundant in various other localities in New York and in Pennsylvania.
Although they differ considerably in composition, size of grain, and color,
all are dense, compact, hard, and usually dark, and, particularly in the
upper beds, split into thin and uniform slabs. The term "bluestone"
therefore is applied to all varieties, irrespective of color. Blue, gray,
red, pink, and greenish colors have been observed.

Composition of Bluestone. — After making a microscopic study of
bluestone from Ulster County, N. Y., Berkey'^ states that the rock
consists of feldspars, quartz, sericite, chlorite, calcite, clay, and a little
pyrite and organic matter. Hornblende and biotite probably were
present in the rock originally but have altered entirely to the more stable
sericite and chlorite. The grains are angular and are held together with
a strong, siliceous cement. Although certain variations in composition
and texture may occur in bluestone from different localities, in general
they are all of this type.

Structural Features. Joints. — Joints usually are in two vertical
systems, nearly at right angles to each other and spaced 5 to 70 feet
apart. Generally the systems are north-south and east-west; the
former are termed "heads" and the latter "sides." Usually joints are

^1 Berkey, C. P., Quality of Bluestone in the Vicinity of Ashoken Dam. Columbia
Sch. Mines Quart., vol. 29, 1907-1908, pp. 154-156.

98 THE STONE INDUSTRIES

straight, though sometimes they are curved and irregular. Moderately
spaced straight joints are of great assistance in quarrying.

Beds and Reeds. — Most bluestone beds lie horizontal or nearly hori-
zontal. Open bedding planes are a few inches to several feet apart,
or in the massive rock may be at 25- to 35-foot intervals. Inter-bedded
shales are common, such rock being termed "pencil" by quarrymen.

The chief characteristic of bluestone is its weak cohesion in certain
well-defined planes, resulting in a strong tendency to split in thin sheets
that parallel the bedding. In the upper beds the partings usually are
developed to such an extent that the rock splits with great ease into
large, thin slabs. At greater depths the partings are less pronounced,
though in most beds the rock may be split easily along certain streaks
termed "reeds," which have already been defined. The presence of
reeds has made bluestone a valuable rock for the production of flagging.

In some deposits or in certain parts of deposits reeds are lacking.
Cross-bedding may be present, or the rock may be massive — a "liver
rock." In some quarries such beds are avoided because flagging can
not be made from them. However, they are the strongest and most
durable and therefore the most valuable for structural purposes.

Run. — In bluestone there is usually one vertical plane in which
splitting is comparatively easy. This is known as the "run" of the rock
or the "free way," and the vertical plane at right angles to it is termed
the "hard way." Fortunately in most deposits the run parallels one of
the major jointing systems, thus permitting easy separation of right-
angled blocks.

Strength and Durability. — Good-quality bluestone is very strong.
Berkeyi^ states that the great strength of the rock is due to the facts that
alteration of the ferromagnesian and aluminous minerals has freed
considerable secondary quartz, which has attached itself to the original
quartz grains, making them more angular and developing an interlocking
texture, and that the secondary fibrous minerals have promoted further
interlocking of the grains.

Bluestone is probably the most durable of any quarried stone except
quartzite. The coarse-grained varieties are somewhat more resistant
to weathering than those of finer grain. The presence of clay in a
bluestone renders it less durable. In natural outcrops of bluestone along
steep hillsides the more durable beds can be recognized easily by their
steep, almost clifflike contour, whereas the softer, more easily weathered
beds outcrop as more gradual slopes. Thus, if the ledge consists of alter-
nate hard and soft beds, the face of the hill will present a series of terraces.

Uses. — Bluestone has been used very widely for sidewalks and flagging.
It is well-suited for these purposes, as it resists wear and does not become

12 Berkey, C. P., Work cited, p. 157.

SANDSTONE 99

slippery. Bluestone with the reeds spaced more widely than in sidewalk
stone is used for curbing, steps, sills, caps, water tables, and coping.
Heavy mill blocks are sawed into forms suitable for the various purposes
mentioned above, or into building blocks. The rock is used to some
extent for floor tile. Various colors may be combined to make attrac-
tive floor patterns or borders. The more massive varieties of bluestone
are suitable for heavy masonry.

Commercial Types. — The primary product of the quarry is marketed
in three forms — flagging, "edge stone," and "rock" or mill blocks.
Flagging is stone from beds that split with remarkable ease into thin,
uniform sheets. Commonly the slabs are 10 by 12 feet and only 2 inches
thick. What is termed "edge stone" splits out in thicker beds and is
dressed for curbing, sills, caps, and coping or other similar uses. " Rock "
or mill blocks are taken from the more massive beds that are not reedy
and are therefore well-suited for structural purposes. Mill blocks are
more valuable per cubic foot than the other forms quarried.

Quarry Methods. Types of Quarries. — Bluestone quarrying differs
from most other types because there are few large operations and many
small ones. Numerous small openings quarried by one to eight men are
operated in summer, some being worked only at brief intervals in connec-
tion with farming or other occupations. The product is hauled by teams
or automobile trucks and sold to stone dealers. Although the quarries
are small, total production amounts to considerable quantities; New
York and Pennsylvania, the chief producing States, normally sell annually
an amount valued at about $1,000,000 at the quarry.

Quarry Equipment. — In many small quarries the equipment is limited
to the necessary tools and appliances, such as crowbars, shovels, hammers,
points, drills, wedges, picks, plugs, and feathers. In numerous quarries
no derricks are provided, the rock being handled by crowbars. Hand-
power or horsepower derricks are common, though steam or gasoline
engines are employed in some places. Some derricks are provided with
gears giving two speeds, a rapid speed for light loads and a slow speed for
heavy loads. Some of the larger quarries have compressed-air plants for
operating drills. For drainage purposes steam or gasoline pumps or
pulsometers are operated in a few places. In others, siphons are employed,
and in many quarries conditions favor automatic drainage. A black-
smith shop for sharpening and shaping tools is a necessity at every quarry.

Separation of Larger Masses. — When vertical seams occur in two
systems at right angles to each other and 10 to 30 feet apart they are of
great assistance in quarrying, and the quarryman endeavors to work to
these seams wherever possible. Where seams are far apart artificial
cross breaks must be made, a process known locally as "snubbing,"
which usually is accomplished by drilling holes about 6 feet apart and
blasting by the Knox method, as described on a previous page. The

100 THE STONE INDUSTRIES

masses thus separated may be 15 or 20 feet in lateral dimensions and
1 to 3 or 4 feet thick depending upon the spacing of the open-bed seams.
Another method less commonly used is to drill a row of holes 1 or 13^
inches apart and to broach out the cores between them, making a
continuous cut.

Cross Breaks. — For smaller cross breaks, particularly those in thin-
bedded rock, the wedging method is employed. In drilling wedge holes a
"starter" and a ''follower" are sometimes used. The starter drill is
commonly l^i inches in diameter and drills only the upper 13^^ inches of
the holes. Then the follower, a drill of J^ inch diameter, finishes the
holes. In the process of wedging in such holes the pressure of the plugs
and feathers comes at a point some distance below the surface of
the rock, whereas if the holes are of the same size throughout their full
depth the pressure is inclined to be excessive near the surface, causing
the rock to shell off. A row of pick holes along the line helps to make a
straight break. Wedge holes may be spaced considerably farther apart
when splitting parallels a pronounced run than when a break is made
parallel with the hard way.

For separation of large masses blasting sometimes gives better results
than wedging. A charge of black blasting powder fired in a single
reamed hole may make a straight break 12 to 18 feet long and 3 to 4 feet
deep. In many quarries it is customary to blast the rock parallel with
the run and to wedge it the hard way.

Splitting Beds. — In rocks in which the reeds are pronounced, beds are
easily split by wedging, but more massive rock, with greater difficulty.
A typical method is to cut notches about }^ inch deep and 3 inches apart
across both ends and along one side of the block. A fracture is started
by driving points into the holes successively first at one end of the block
and then at the other end. When a fracture is formed some distance from
each end thin wedges are driven into it at both ends and on the edge.
The block is then turned down and started on the opposite edge, and the
fracture is completed by wedging. When the process is thus carefully
conducted it gives a uniform fracture. A bull wedge sometimes is used in
splitting curbstones.

Trimming. — There is usually need of trimming edges, especially
where such products as curbstones, steps, and coping are made. Where
curved corner curbstones are made much trimming is necessary.
With careful handling two corner curbs may be broken from a single
block by making a curved break. The amount of trimming required is
influenced by cross bedding, which may result in oblique splitting of
beds. If a slab for curbstones is thicker at one edge than the other, it is
"pitched off" with a hand tool and hammer, a process that wastes rock
and requires much time and labor. When trimming is done in the
quarries hand tools and hammers generally are employed.

SANDSTONE 101

Marketing Bluestone. — Operators of the many small bluestone
quarries sell their products to stone dealers, or dealers may operate the
quarries themselves. They have yards termed "docks," situated on
navigable water or railway lines, where stone from the quarries is unloaded
and shipped by rail or water to its destination. The docks almost
invariably are equipped with derricks. Transportation is usually by
wagons and trucks, as very few quarries have railway sidings. The cost
of transportation is borne by the quarryman and ranges from 8 to 50
per cent of the value of the stone, depending on the haulage distance and
the condition of roads. Structural stone is sold to building contractors,
and curbing and flagging to street-construction contractors, highway
boards, or municipalities.

WASTE IN SANDSTONE QUARRYING AND MANUFACTURE'

Cause of Waste. — Even in sandstone deposits of the highest quality
much rock is either unsuitable for use or is wasted in quarrying
and manufacture. Much of the waste may be due to imperfections in the
rock, over which man has no control. Joints may be irregular or closely
spaced, or they may intersect at sharp angles. Bed seams may be close
together or wavy and uneven, or the rock may be cross-bedded, with
intersecting bed seams. The texture may be uneven, and the degree of
cementation may lack uniformity. Iron compounds may cause stains,
and the presence of clay may increase the absorption. Such defects in
composition and structure may bring about the rejection of many blocks
of stone.

Much serviceable rock is wasted in quarrying and milling. Excessive
blasting with unnecessarily heavy charges, the ''stunning" of channeling
machines, and improper wedging are common causes of excessive waste.
Even in the best-conducted quarries and mills part of the good stone must
be cut and trimmed away to fashion blocks and slabs to their required
shapes and dimensions. Therefore, the volume of finished products
may be less than one-half of the gross quarry output.

Waste Utilization. — Sandstone is chemically inert, and its waste
products therefore have much more limited application than waste lime-
stone or marble. However, the economical quarryman seeks to cultivate
certain fields of utilization to win some profitable return from at least
part of his waste material. Heavy, irregular blocks of sandstone unsuit-
able for other use may be used for shore protection along rivers, for
spillways at dams, or for the construction of harbor breakwaters. Irregu-
lar small fragments which have one good face are used to some extent as
rubble, though rubblestone has been displaced by concrete quite generally
during recent years. Waste blocks may also be trimmed to suitable
sizes and shapes for regular course or broken ashlar walls. Waste sand-
stone may be crushed for concrete aggregate. As a rule, sandstone is not

102 THE STONE INDUSTRIES

suitable for road surfaces, although some argillaceous sandstones contain
enough binding material to render them satisfactory. Some quartzites
are used for road surfaces where traffic is heavy. Sandstones are more
suitable for road bases, as they provide good drainage and cushion,
and a market for waste is found in this field.

Sand is an important by-product at many sandstone plants, especially
where the more friable types are worked. The sand may be used for
sand-lime brick manufacture, for mortar, for furnace floors, or as engine
sand. The utilization of pulverized sandstone as asphalt filler is receiv-
ing some attention.

Prevention of Waste. — In view of the limited number of uses for
which waste sandstone may be employed, quarry operators endeavor to
keep the proportion of waste at a minimum by quarrying in accordance
with joint systems and other rock structures, by exercising great care in
blasting, by employing skill and good judgment in wedging, and by
careful selection of rock that it may be suitable for its intended use.
Waste may be reduced by skillful milling. Blocks containing streaks
or spots may be cut in such manner that the blemishes do not appear
on exposed surfaces. There is an advantage in operating a mill in con-
nection with a quarry, for the quarryman understands his rock and can
therefore cut it to much better advantage than a millman unacquainted
with its peculiarities.

Bibliography

AuBURY, Lewis E. The Structural and Industrial Materials of California. Cali-
fornia State Min. Bur. Bull. 38, 1906, pp. 114-116.
Bowles, Oliver. Sandstone Quarrying in the United States. U. S. Bur. of Mines

Bull. 124, 1917, 143 pp.
BowNOCKER, J. A. Building Stones of Ohio. Geol. Survey of Ohio, 4th ser., Bull.

18, 1915, 160 pp.
Eckel, E. C. Building Stones and Clays. John Wiley & Sons, Inc., New York,

1912, pp. 127-149.
Galliher, E. Wayne. Geology and Physical Properties of Building Stone from

Carmel Valley, California; Mining in California. California Dept. Nat. Res.,

Div. of Mines, January, 1932, pp. 14-41.
Richardson, Charles H. Building Stones and Clays. Syracuse Univ. Book Store,

Syracuse, N. Y., 1917, pp. 229-266.
Stone, R. W. Flagstone Industry in Northeastern Pennsylvania. Pennsylvania

Bur. Topog. and Geol. Survey Bull. 72, 1923, 7 pp.
Building Stones of Pennsylvania. Pennsylvania Topog. and Geol. Survey

Bull. M15, 1932, 316 pp.

CHAPTER VIII

GRANITE
GENERAL CHARACTER

As pointed out in the discussion of rock classification, granite is of
igneous origin, coming up from unknown depths; thus, except in rare
instances, it may be rehed upon to extend downward far beyond the
possibihty of economical quarrying. Granites and related rocks are
the hardest of all ordinarily used for structural purposes and the most
difficult and expensive to quarry and shape into finished forms. The
many troublesome problems that confront the granite quarryman have
stimulated his inventive genius to devise new and better ways of winning
this important structural material from the earth and fashioning it
into useful and attractive products. The technology of granite is
therefore, of unusual interest.

MINERAL COMPOSITION

Chief Minerals. — The essential constituents of granite are feldspars,
quartz, and either mica or hornblende; and their proportions vary
greatly. According to Merrill, ^^ one European granite contains 52 per
cent feldspars, 44 per cent quartz, and 4 per cent mica; another contains
35 per cent feldspars, 59 per cent quartz, and 6 per cent mica. Granites
as high in quartz as these are very difficult to work, but few quarried in
the United States have as large a proportion as these foreign granites.
The red granite of St. Cloud, Minn., contains 70 to 80 per cent feldspars,
15 to 20 per cent quartz, and 5 to 10 per cent combined mica and horn-
blende. Dale^* found that a Hardwick (Vt.) granite contains about 62
per cent feldspars, 22 per cent quartz, and 16 per cent biotite mica. He
also states^^ that dark Barre granite contains about 65 per cent feldspars,
27 per cent quartz, and 8 per cent mica.

A simple method of determining the proportions of the chief constit-
uent minerals is described by Dale.^** A network of lines intersecting at
right angles is traced on the polished surface of granite and spaced at
such intervals that no two parallel lines will traverse the same mineral

1^ Merrill, G. P., Stones for Building and Decoration. 3d ed., John Wiley & Sons,
Inc., New York, 1910, p. 46.

1* Dale, T. Nelson, The Commercial Granites of New England. U. S. Geol.
Survey Bull. 738, 1923, p. 110.

1* Work cited, p. 124.

" Work cited, p. 100.

103

104 THE STONE INDUSTRIES

grain. The total length of the lines is measured, the diameters of all
the particles of each mineral variety are added separately, and their
proportion to the total length of the lines is calculated.

Feldspars are the most conspicuous and ordinarily the most abundant
minerals in granites. Several kinds usually are present. The potash
feldspars (microcline and orthoclase) are the most prevalent and are
generally accompanied by small percentages of one or more members of
the lime-soda group (the plagioclases). Feldspars may be white, gray,
opalescent, reddish, brown, or green, and the prevailing color determines
to a large extent that of the rock. Quartz grains may be recognized
readily by their glassy luster, absence of cleavage, and uneven fracture
surface. Quartz is commonly clear and transparent but may be milky,
bluish, yellow (citrine), opalescent, purple, or smoky. Next to the
feldspars and quartz, black mica (biotite) is the mineral most abundant
in a majority of granites; dark green or black hornblende may be nearly
as abundant ; and muscovite frequently occurs. When large percentages
of biotite or hornblende are present the rock may be nearly black.

Accessory Minerals. — Accessory minerals are those that may or
may not be present in a rock. When present they are usually in sub-
ordinate amounts, and some may be detected only with a microscope.
Garnet, zircon, epidote, titanite, magnetite, hematite, limonite, ilmenite,
pyrite, apatite, augite, and rutile are the more important accessory
minerals of granite, and minute quantities of many others may occur.

CHEMICAL COMPOSITION

The chemical composition of granite has little economic significance.
Many prospective granite-quarry operators wish to have samples of
their rock analyzed to determine its quality and probable value, failing
to realize that any one element or compound may form constituent
parts of several different minerals, some of which may be desirable and
some undesirable. For example, an analysis may show a certain amount
of iron, but without a very complete analysis and careful calculation the
amount of iron present as a constituent of a stable biotite or hornblende
or of an unstable and detrimental pyrite or garnet can not be determined.
A chemical analysis, however, may indicate the general composition;
thus a high silica content would indicate a high percentage of free quartz.
Analysis of a granite is therefore much less important than determination
of its mineralogical composition.

PHYSICAL PROPERTIES

The adaptability of a granite for structural or ornamental use is
governed mainly by its physical properties, the character of its con-
stituent minerals, and their grouping.

GRANITE 105

Texture. — The texture of granite signifies the size and arrangement of
mineral grains. Uniform grain size usually is demanded in commercial
granites for building or ornamental uses. Lack of such uniformity
condemns thousands of deposits throughout the world for practical use.
Grain size varies greatly in different granites. They accordingly are
classed as fine-, medium-, and coarse-grained. Medium-grained granites
are those in which the feldspars average about one-fourth inch across.

Uniform distribution of the minerals is as important as uniform
grain size. Light and dark minerals should be distributed evenly
throughout the rock mass, for this gives uniform color and texture.
Many commercial deposits display remarkable homogeneity; the rock
may not vary in color or texture for many feet, either vertically or
horizontally. A number of granite enterprises owe their success to such
consistent qualities.

Color. — The color of a granite is governed largely by that of the
feldspar, usually the most abundant mineral. However, it may be
modified to some extent by the quartz, hornblende, or mica, if consider-
able amounts are present. White, light gray, dark gray, pink, red, and
olive-green commercial granites are common. Uniform color distribu-
tion is a desirable feature.

Hardness. — The hardness of a granite is determined by that of its
constituent minerals. As feldspar and hornblende have a hardness of
about 6, and quartz of 7, all granites must be exceedingly hard. Those
having abundant quartz are the hardest. Some are quite brittle and
shatter readily, while others have interlocking grains that make them
very tough and consequently difficult to separate by blasting or wedging.

Porosity. — Although freshly quarried granite appears very dense and
impervious to moisture, investigations by Merrill, Watson, Buckley,
Parks, and others show that the pore space of average granites is 0.10 to
0.50 per cent. These microscopic pores are both within and between
the mineral particles. Dale^^ states that an average granite contains
0.8 per cent water and can absorb about 0.2 per cent more; that is,
1 cubic yard of granite weighing about 2 tons contains about 33^^ gallons
of water and if immersed can absorb nearly 1 gallon more.

Although the total pore space is very small it may have interesting
effects. Pores of subcapillary size do not give up their water content
readily and damage from frost action may result. As will be shown later,
the fluidal cavities in quartz probably bear definite relation to the rift.

VARIETIES

Granites generally are named from the most prominent ferro-mag-
nesian mineral present; thus, they may be called "biotite granites,"
"hornblende granites," or, more rarely, "augite granites." If two such

" Work cited, p. 12.

106 THE STONE INDUSTRIES

minerals are prominent a compound word may be used, as "hornblende-
biotite granite." The name "binary granite" is sometimes given to one
consisting only of quartz and feldspars. Sometimes granites are named
from an unusually prominent accessory mineral, as "epidote granite"
or "tourmaline granite." Classification by color provides for red,
gray, white, or other groups.

Granites are also classed according to texture. They may, for exam-
ple, be designated "fine-grained" or "coarse-grained." "Porphyritic
granite" consists of relatively coarse grains in a fine-grained groundmass.
The term "aplite" is usually applied to a fine-grained, light-colored
granite that occurs in dikes. A rock may have the mineral constituents
of a granite but show a banded arrangement of light and dark minerals,
owing to folding while the rock was plastic or semimolten. Such meta-
morphic rocks (gneisses) are classed commercially with the granites and
may be designated "gneissic granites."

RELATED ROCKS

Granite is only one of many igneous rocks, but it occupies so promi-
nent a place in any discussion of dimension stone that the other less
important types are included with it. When igneous rocks are considered
for building and similar purposes granite predominates for two reasons.
First, there are few other igneous rocks of composition, texture, or color
suitable for structural or ornamental uses. Second, most igneous
rock types so employed are classed commercially as granites, even though
some are far removed petrographically.

Certain related varieties are logically classed with granites, as they
are so similar as to be distinguishable only by very careful examination,
sometimes only by the use of a microscope. The more prominent of
these closely related types are syenite, diorite, quartz diorite, and
quartz monzonite.

Other rocks classed commercially as granites differ sharply from them.
The most important of the distantly related types are the so-called
"black granites," which may be gabbros, diabases, or dark diorites.
They are similar to true granites in structure and texture but consist
essentially of plagioclase feldspar and augite, with little or no quartz.
Some are quite ornamental, will take a high polish, and are used in the
same way as granites. Rhyolites and volcanic tuff, uses of which are
limited, also are distantly related to granites.

STRUCTURAL FEATURES

Certain structural features affect both the quality and workability
of granite. Joints, sheet structure, rift, grain, dikes, knots, and hair
lines are the most important.

Joints. — Joints, or seams, are natural fractures that traverse the
granite mass, usually in a nearly vertical direction. Pynamic geologists

GRANITE

107

generally agree that they are caused by compressive or torsional strain,
which has been resolved into two components, each at an angle of about
45° with the direction of strain. This theory has some confirmation in
the fact that joints occur quite generally in two main systems, called
"major" systems, which intersect at about 90°; less prominent systems
are termed "secondary." Joints may have resulted from a constant
force exerted in one direction over a wide area, for the systems tend to
run in the same compass directions in many quarries throughout an
extended deposit. Thus, in the St. Cloud (Minn.) region, where the

Fig. 21. — Strike of major and secondary joints in granite deposits near St. Cloud, Minn.

writer some years ago took numerous compass readings, most of the
major joints strike either approximately north and south or east and
west, as shown diagrammatically in figure 21.

Major systems are common in granite deposits, but many inter-
mediate and irregular joints may occur, and in some deposits no sys-
tematic arrangement may be evident. Obviously an arrangement in
two parallel systems meeting at right angles, with few intermediate or
irregular joints, is the most favorable for quarrying, as it facilitates
removal of blocks and maintains a low percentage of waste.

The spacing of joints is extremely variable. If they are only a few
inches apart the rock is useless as dimension stone, except possibly for
small rubble. Straight major joints 10 to 30 feet apart usually are
regarded as advantageous in quarrying. If only 3 or 4 feet apart, blocks
of sufficient size may be obtainable, but the rock may be stained by
weathering agencies acting from the joint walls. Such staining detracts
from its quality for memorial uses but may be an asset for certain archi-

108 THE STONE INDUSTRIES

tectural effects now in demand. In some localities, such as the Lithonia
district of Georgia and the Mount Airy region of North Carolina, the
rock may be sound and massive over wide areas without any joints.

Sheeting Planes. — Sheeting planes are approximately horizontal
partings that separate a granite mass into sheets or layers. They
generally parallel the rock surface and are consistently closer together
near the surface than at depth. In some granites they are very promi-
nent and closely spaced. On Crotch Island, Me., they are only 2 to
4 feet apart near the surface and present, although more widely spaced, at
a depth of at least 140 feet. Widely separated sheeting planes occur at
a depth of 250 feet at Quincy, Mass. In the St. Cloud district, Minne-
sota, they are few and widely separated. As a rule, they are more closely
spaced than joints in New England, while the reverse is true in Min-
nesota. On this account quarrymen who have worked both in New
England and in the St. Cloud district describe the rock of the latter
region as "standing on end." Just as the granites of Lithonia, Ga., and
Mount Airy, N. C, are crossed by few joints, so are they without sheet
structure. In such deposits artificial sheets must be forced in the process
of quarrying.

The origin of sheeting planes is obscure. Dale^^ discusses in some
detail all the theories advanced, concluding that compressive strain
was probably the main factor in producing them, though expansion under
solar heat may have been a contributory cause in the surface layers.
The arched structure commonly found in sheeting planes may account
for the conspicuous domelike form that characterizes many granite
deposits.

Rift and Grain. — Many granites split in some directions with greater
ease than in others. The direction of easiest splitting or the fracture
system that makes splitting possible is called the "rift." A second
less strongly marked fracture system may stand at right angles to the
rift. It is generally called the "grain," but in Minnesota it is called
the "run." The direction at right angles to both rift and grain is
called the "hard way" or "head grain."

In Minnesota the rift is nearly always horizontal, and the grain in
some vertical plane. In many Vermont and Maine quarries conditions
are reversed, the grain usually being horizontal and the rift vertical.
In New Hampshire conditions more nearly resemble those in Minnesota.
There are many variations, but one direction of comparatively easy
splitting is almost invariably horizontal and the other at right angles to it.
The direction of grain may be constant over a wide area. Thus, through-
out central Minnesota the grain like the major joints is predominantly
north and south, except in one small area where it is east and west.

18 Work cited, pp. 26-36.

GRANITE 109

The origin of rift and grain, like that of sheeting planes, is obscure.
They are apparently independent of sheets and of flow structure. Ac-
cording to Dale they are caused principally by orientation of the minerals
— that is, by the arrangement of the minerals in lines or planes or with
parallelism in their cleavage directions. They may also be caused by
the arrangement of fluidal cavities in parallel planes in the quartz grains;
by incipient jointing caused by strain; or by microscopic faults or frac-
tures. That rift and grain in the granites of central Minnesota originated
in orientation of minerals is indicated rather definitely by two facts:
First, the rift surface is smoother than other surfaces. A skilled paving-
block cutter can detect the rift blindfolded by the feel of the surface.
This condition would indicate predominance of feldspar cleavage faces
parallel to the rift. Second, some quarrymen have stated that they
recognize the rift by "the direction in which the grains point." They
appear to base their observations rather on the dark than on the light
minerals.

Some granites display no evidence of rift or grain. Even in rocks
in which they are most fully developed rift and grain are obscure proper-
ties that may be recognized only by a skilled stonecutter. Nevertheless,
they are of the utmost importance in quarrying, as they make splitting
easy and give comparatively smooth, uniform surfaces. Paving-block
cutters are exceptionally skilled in recognizing rift. It may be safely
said that the granite paving-block industry could not exist were it not
for rift and grain in the rock.

Dikes. — Dikes are defined as fissures filled by mineral matter injected
in a plastic to fluid condition. Dike material is of two main types —
acidic or basic; that is, it may be siliceous, like granite, or may contain
a large percentage of ferromagnesian minerals, thus having the composi-
tion of a basalt or diabase. Dikes in granite deposits may range in
width from a fraction of an inch to several feet and occasionally to 50
or even 150 feet.

Acidic Dikes. — Some dikes consist of granite which differ radically
from that into which it is injected. In Minnesota, red granite dikes
commonly traverse gray granites. The well-known granites of Westerly,
R. I., are quarried in a formation that has been interpreted as a great
dike 50 to 150 feet thick. The occurrence of commercial granite in dike
form is quite exceptional.

Aplite dikes — fine-grained, light-colored granite — are very common.
They are usually quite narrow, and their fine-grained texture probably
is due to comparatively rapid cooling caused by contact with the previ-
ously solidified rock masses on either side.

Pegmatite, according to Hess,^* is a general name for rocks with
coarsely and unevenly crystallized segregated minerals occurring as

19 Hess, Frank L., Pegmatites. Econ. Geol., vol. 28, no. 5, 1933, pp. 447-462.

110 THE STONE INDUSTRIES

dikes, veins, or metamorphic masses. During their formation the
constituents of ordinary granite were supplemented by water vapor and
numerous volatile elements, such as fluorine, chlorine, boron, phosphorus,
and sulphur. A slow process of crystallization and mineral replacement
caused large crystals of feldspar, quartz, and mica to form, and associated
with them in many places was a series of characteristic pegmatite min-
erals, such as tourmaline, scheelite, garnet, cassiterite, apatite, and beryl.

Pegmatites supply practically all the feldspar and sheet mica of
commerce but have little value as sources of structural or ornamental
stone.

Basic Dikes. — The more common types of basic dikes are those
termed "diabase" or "trap" dikes. They are dark green, dark gray,
or black, are very hard and dense, and are common in many granite
regions. More than 360 have been counted in the Rockport quarries,
Cape Ann, Mass.

Effect of Dikes on Granite. — Granite traversed by dikes of any kind
rarely is utilized as dimension stone. Basic dikes, particularly, stand
out as dark, conspicuous bands that mar the appearance of the stone.
They are unwelcome in quarries because of the time and labor wasted in
removing them and of the granite they render valueless commercially.
It has also been observed that rock near dikes tends to be unsound.
Such a condition is to be expected, because the shattering which formed
the open fractures into which the dike material was injected may have
developed fine cracks or incipient seams in the near-by rock.

In some deposits, however, granite close to dikes, though not actually
cut by them, may be of good quality. The heat of the dike material
may have developed minute cracks in the quartz and feldspar of the
adjoining granite, but this contact effect may not extend beyond a depth
of 1 or 2 inches.

Knots. — The term "knot" is applied to a circular, oblong, or irregu-
lar mass that commonly occurs in a granite otherwise of uniform texture.
Knots are usually dark and are regarded as serious blemishes, par-
ticularly on polished surfaces, where they stand out like blots on a sheet
of paper. As they in no wise affect strength or durability, stone con-
taining them may be used for curbing, paving, or other purposes where
color means little. Knots are of two kinds — segregations and inclusions.

The more common types are segregations — groupings of dark minerals
in spots during cooling and solidification. Segregations consist of the
same minerals as the parent rock; but the dark minerals, hornblende
and biotite, are more abundant than the light quartz and feldspar. Both
the origin and distribution of segregations are difficult to explain. No
conclusions have been reached regarding their occurrence, and the
probability of their presence or absence in any locality is a matter of mere
speculation.

GRANITE 111

Knots designated as "inclusions" are masses of foreign material
caught up by a semiliquid magma and held within it until the whole has
solidified. Such knots are somewhat angular and comprise material
different from the rock in which they are inclosed. As inclusions consist
of foreign materials they are most apt to occur near the borders of granite
masses — that is, in the zones nearest contact of the granite with other
rocks.

Methods of Distinguishing Knots. — As noted previously, some rules
can be laid down for the occurrence of inclusions, but none have been
established for segregations. At times, therefore, it is rather important
to interpret the origin of knots and classify them correctly. A specific
example best illustrates the method of interpretation. In a certain
granite two types of knots occur. Microscopic examination in thin
section reveals that one consists of orthoclase, plagioclase, quartz, and
biotite, the same minerals that occur in the surrounding rock, though the
proportion is different, biotite being in excess. These minerals have the
same peculiarities as corresponding minerals in the main rock mass; for
example, the biotite contains inclusions of apatite and zircon, a condition
characteristic of this granite. Such knots are undoubtedly segregations.
The other type of knot is quartz and biotite, with no feldspar. The mica
flakes show parallel orientation and have no inclusions of apatite or
zircon. Therefore, the minerals have different characteristics from
corresponding minerals in the surrounding rock, and their character and
arrangement suggest the probability that the knot is an inclusion of
biotite schist. The shape of knots is also indicative of their origin,
angular knots being inclusions and ellipsoidal or spherical knots more
probably segregations.

Hair Lines. — The term "hair line" is applied in some regions, par-
ticularly in Minnesota, to all fine lines of discoloration in granite. These
lines are practically unrecognizable on rough or tooled granite and
therefore are objectionable only on polished surfaces, where they stand
out quite prominently and detract greatly from appearance. Some
black hair lines appearing in granite close to trap dikes are really minute
dikes; others are very small veins filled with dark or smoky quartz.
Green hair lines, consisting of epidote veinlets, are common. If they
follow joint systems they are unimportant, but if they wander irregularly
they may mar the stone. Quarrymen examine rock very carefully for hair
lines before selecting it for monumental purposes. They can be observed
best if water is thrown over the surface.

USES

Dimension granite is used for five principal products. These are, in
order of their production value: Monumental stone, building stone,
paving blocks, curbing, and rubble. Only stone of the highest quality is

112

THE STONE INDUSTRIES

used for monuments, because much of it is polished and polishing empha-
sizes all defects. Increasing quantities of polished granite are being
used also for structural purposes, not only because it is attractive, but
because it is easily cleaned and is not soiled so quickly as unpolished
granite; therefore, highly ornamental stones, as well as the more
ordinary types, are used for building. For paving blocks and curbing
appearance is less important.

The following table, compiled by the United States Bureau of Mines,
indicates the amount and value of granite sold for various uses.

Granite Sold or Used by Producers in the United States, 1936 and 1937,

BY Uses

Use

1936

Juantity

Value

1937

Quantity

Value

Building stone (rough and dressed), cubic feet.

Approximate equivalent in short tons

Monumental stone, cubic feet

Approximate equivalent in short tons

Paving, number of blocks

Approximate equivalent in short tons

Curbing, linear feet

Approximate equivalent in short tons

Rubble, short tons

2,619,700

217,070

2,478,380

203,610

6,826,333

70,500

1,189,680

98,220

77,450

Total value.

2,629,090
6,440,878

702,828

1,206,113

117,835

$11,096,744

3,322,830

274,930

2 , 657 , 630

218,400

7,866,994

73,770

881,310

72,790

111,440

$ 3,068,155

6,628,447

780,611

825,148

149,958

$11,452,319

The corresponding total for 1929 was $25,369,396 and for 1932,
$11,743,408.

DISTRIBUTION OF DEPOSITS

Granites are quarried in many parts of the United States, but the
principal deposits may be grouped in four chief areas, as follows: (1) The
Appalachian district of eastern United States, from Maine to Georgia;
(2) the Middle Western States, particularly Minnesota and Wisconsin; (3)
the Rocky Mountain States, where deposits have not been developed
extensively; and (4) the Pacific Coast States, particularly California.
The general distribution of granites in the United States is shown in figure
22. The leading producing centers for monumental granite are Barre,
Vt., Quincy, Mass., and St. Cloud, Minn. In order of production value
of monumental stone in 1928 the 10 leading States were Vermont,
Minnesota, Wisconsin, Massachusetts, California, Georgia, Rhode Island,
North Carolina, New Hampshire, and Maine, which produced about 86
per cent of the total. The 10 leading States in order of production value
of building stone for the same year were Massachusetts, Minnesota,

GRANITE

113

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114 THE STONE INDUSTRIES

North Carolina, New York, New Hampshire, Maine, Georgia, Mary-
land, Pennsylvania, and Vermont. The totals and relative standing
of the States vary from year to year. Figures may be obtained from the
U. S. Bureau of Mines, which annually publishes complete statistics by
States and uses.

INDUSTRY BY STATES

About 96 per cent of the production value of granite dimension stone is
confined to 16 States, which may be arranged in two groups, those of
major importance as producers and those less important. The first
group, comprising the following States, listed in order of production in
1928, furnished about 81 per cent of the total quantity for that year:
Vermont, Massachusetts, Minnesota, North Carolina, Maine, Georgia,
Wisconsin, and New Hampshire. The second group, accounting for
about 15 per cent of the total production, included New York, California,
Maryland, Rhode Island, Connecticut, Pennsylvania, South Dakota, and
Texas.

The order of arrangement of the States and much of the statistical
data given in the following pages are based on 1928 production because
a fairly complete analysis of the 1928 figures has been published. -°

Principal Producing States

Vermont. — Vermont, with an output valued in 1928 at $4,227, 525, or
17.1 per cent of the total for block granite in the United States, is the
largest producer in the country. It specializes in monumental stone, a
material that accounts for about 96 per cent of the total value of granite
produced in the State. About 36 per cent of the monumental stone of the
United States was produced in this State in 1928. The total output in
1929 was valued at S4, 113,886, in 1930 it was $3,348,938, in 1936, $2,238,-
724, and in 1937, $2,511,986.

In this and in most of the States the granites are described briefly by
counties in alphabetical order.

Caledonia County. — The Newark rock is a coarse-grained, light
pinkish gray biotite granite marketed as "Newark pink." The Kirby
Mountain granite, which is bluish gray and medium- to fine-grained, has
been worked to a limited extent. The Hardwick granites, which are
fine to medium, even-grained and bluish gray, are well-known to the
monument trade as "Hardwick" and "Dark Blue Hardwick." Typical
"Ryegate" granite, also known as "Vermont gray," is a medium-grained,
light gray stone suitable for monuments or building. Stone of a decided
blue-gray, "Vermont blue," is quarried at Groton.

20 Bowles, Oliver, and Hatmaker, Paul, Trends in the Production and Uses of
Granite as Dimension Stone. Rept. of Investigations 3065, Bur. of Mines, 1931, 21 pp.

GRANITE 115

Orleans County. — The rock at Derby is a fine-grained, light bluish
gray biotite-muscovite granite, sold chiefly for monuments and monu-
ment bases under the trade name "Derby Gray." Sheeting planes are
3 to 18 feet apart, and one set of vertical joints provides a heading at the
north wall of the quarry. Quarrying was begun about 1880.

Washington County. — The district surrounding Barre and Graniteville,
Washington County and Williamstown, Orange County is the most
important monumental granite-producing center in the United States.
The granite occurs in two prominent domes. Cobble Hill and Millstone
Hill; the latter supplies most of the commercial stone. The two hills
are regarded as parts of a single mass appearing at or near the surface in
an area 4 miles long and 23-^ miles wide. The rock is a fine- to medium-
grained gray to white biotite granite ; the various shades are designated as
"white Barre," "light Barre," "medium Barre," "dark Barre," and
"very dark Barre." The darker varieties are most in favor for monu-"
ment dies and the lighter for buildings, mausoleums, and monument
bases. An average sample of dark Barre granite consists of about 65
per cent feldspars, 27 per cent quartz, and 8 per cent mica.

Sheeting planes 6 inches to 30 feet apart are present in some quarries;
in others they are spaced more widely or are absent. Masses 40 to 80
feet thick without sheeting planes have been encountered. This incom-
plete development of sheet structure makes quarrying difficult. Joints
are irregular, following at least five different compass directions. The
spacing also is quite variable, ranging in most quarries from 1 to 50
feet and in others from 100 to 200 feet. Black knots rarely occur. Its
remarkably uniform texture is one of the chief assets of Barre granite.
The rift ranges from 85° to vertical and varies somewhat in direction,
on Millstone Hill from N.30°E. to N.60°E., and on Cobble Hill from
N..50°E. to N.75°E. Almost invariably the grain is horizontal. Peg-
matite, aplite, and basic dikes occur but are not numerous.

For many years a dozen or more large companies operated quarries
in this district. Recent consolidations have reduced the number, though
the extent of operations has not been curtailed.

Monumental stone is the chief product. The industry consists of two
distinct branches — quarrying and manufacturing. Some quarry compa-
nies also manufacture ; but most of them produce rough blocks only, which
they furnish to neighboring manufacturing plants and ship to all parts
of the country. Figures compiled by the Barre Granite Manufacturers'
Association show that the quarries of the district produced 1,549,443
cubic feet of rough stock in 1928. Of this amount, 1,239,554 cubic feet
were manufactured in the district and 309,889 cubic feet shipped as
rough blocks. More than 100 plants for the manufacture of granite
products are situated in and about Barre, Montpelier, and neighboring
towns.

116 THE STONE INDUSTRIES

Woodbury granite occurs in numerous outcrops within an area about
33^ miles square occupying the northeastern part of the town of Wood-
bury. The principal quarries are on the southeast flank of Robeson
Mountain where several types of dark to light bluish gray biotite granites
occur. Most of them are porphyritic in texture, with large, scattered
feldspar crystals. The products are known to the trade as ''Woodbury
Gray," "Imperial Blue," "Woodbury Bashaw," and "Vermont White."
They are used for both building and monumental purposes. Woodbury
has produced more building granite than other Vermont quarries, except
possibly those at Bethel.

The Cabot granite is dark bluish gray and of fine, even-grained texture.
It is used for monuments and markers. Quarries at Calais, or more
properly at Adamant, are in a ridge of attractive fine-grained, light gray
biotite granite sold as monumental stone.

Windham County. — The source of Dummerston granite is a dome
about 1 square mile in area which rises approximately 900 feet above
West River, about 5}4 miles from Brattleboro. Sheeting planes 6 inches
to 2 feet apart, in a zone 25 to 35 feet thick with much more widely spaced
sheeting planes both above and below, are an unusual feature. Major
joints strike N.15°E. and are 7 to 30 feet apart. Rift and grain are
pronounced, the former being vertical, with a N.15°E. course, and the
latter horizontal. There are two main types of granite, the better
known being the "Dummerston White," an even-grained, light gray
rock speckled with bronze mica, which is used for building, monuments,
paving stones, and curbing; the second type is a light bluish gray rock
employed for monuments.

Windsor County. — The best known Windsor County granite is
quarried at Bethel, on Christian Hill, a dome at least one half mile long,
550 to 650 feet wide, and 350 feet high. The rock is a bluish or milk-
white muscovite granite, of medium to coarse texture. Sheeting planes
are 6 inches to 8 feet apart. Major joints are variable but follow a
general east-west direction. The rift is horizontal or dips eastward
slightly, and the grain is vertical, with a nearly east-west course in the
largest quarry. "Bethel White" is used for both monumental and build-
ing purposes but is particularly adapted for the latter. The Union
Station and the Post Office at Washington, D. C, were made of this stone.
It is one of the whitest granites quarried and is often mistaken for marble.

A light greenish gray muscovite granite, well-adapted for building,
occurs near Rochester. "Plymouth White," "Windsor Granite," and
"Ascutney Green" are commercial types found near Plymouth and
Windsor.

Massachusetts. — Massachusetts ranked second as a producer of
dimension granite, with an output in 1928 valued at $3,749,668, or 15.2
per cent of the total for the United States. Corresponding figures for

GRANITE 117

1929 are $4,005,083; for 1930, 3,024,669; for 1936, $2,003,302; and for
1937, $1,956,408. Unlike Vermont producers, who specialize almost
exclusively in monumental stone, Massachusetts quarrymen diversify
their production. Of the 1928 production 45.5 per cent was building
stone, 24 per cent monumental, 10.2 per cent paving stones, 18.9 per cent
curbing, and 1.4 per cent rubble. During recent years a gradual increase
in the proportion of building stone has been noted. There are several
important producing centers, notably Quincy, Milford, West Chelmsford,
and Rockport, as well as quite a number of less productive areas scattered
throughout the State.

Berkshire County. — The more important granites of Berkshire County
occur near Becket. The rock is a fine-grained, bluish gray muscovite-
biotite granite with a tendency toward gneissic structure. Two main
types are marketed as memorial stones, "Chester dark" and "Chester
light," the variation in color being due to differences in the proportion
of biotite present. Sheeting planes are 6 inches to 30 feet apart and
thicken gradually with depth. Joints are in two prominent systems,
which intersect at right angles. Gray granite has been quarried at Otis.

Bristol County. — Important deposits of rock in two colors occur near
Fall River in southeastern Massachusetts. "Fall River Pink" is a
pinkish gray, gneissoid, biotite granite; "Fall River Gray" is similar,
except that it is light buff-gray. Both are suitable for rough, massive
construction and for curbing. Sheets are 13^^ to 16 feet thick, and joints
are spaced 20 to 200 feet apart. Pegmatite, aplite, and basic dikes occur
in places, and black knots in the form of inclusions are not uncommon.

About 2 miles northwest of New Bedford is a deposit of substantial
and attractive building granite. The "New Bedford" is a light pinkish
gray biotite-muscovite granite gneiss of coarse texture, cut by an unusual
series of dikes, including diorite, diabase, and pegmatite. Rough and
dressed building stone, paving blocks, and curbing are the chief products.

"Dartmouth" granite is quarried about 8 miles southeast of Fall
River. It is similar to the New Bedford stone, except that it is light
buff-gray. The sheets are 1 to 12 feet thick, the rift is horizontal, and
the grain is vertical. It is used for rough construction and curbing.

Essex County. — An olive-green hornbende-augite granite somewhat
resembling that quarried at Quincy is found in the Peabody-Lynnfield
district, southern Essex County. The rock, known to the trade as
"Peabody Green," is used for trimming, base courses, steps, curbing, and
paving stones.

The most important granites of the county occur on Cape Ann, at
the extreme east. The entire cape is made up of granites and related
rocks, though they are covered in part with sandy hillocks, flats, and
marshes. Rockport granite is of two main sorts — gray and green. The
grays are abundant and are known commercially as "Rockport Light

118 THE STONE INDUSTRIES

Gray," and " Bayview Gray." The latter is a medium- to coarse-grained,
black-spotted gray hornblende granite which is rather hard to work
because of a high content of free quartz. The second type, known as
"Green Granite" or "Seagreen," is a dark, black-spotted, olive-green
hornblende granite. As already stated, a conspicuous feature of the
Rockport quarries is the large number of basic dikes which traverse
them. Pegmatite dikes and black knots are not uncommon. The rift is
generally east-west and vertical, and the grain horizontal. Sheets are
6 inches to 35 feet thick. Numerous joints intersect at various acute
angles. The rock is adapted to a variety of uses. As the location of
the quarries at tidewater is a great advantage for shipping many large
blocks are quarried for docks and other types of heavy shore-line con-
struction. The granite is also used for rough and dressed building stone,
rough and dressed monumental stone, paving blocks, curbing, and rubble.
The two large fountains on the Union Station plaza, Washington, D. C,
are made of the sea-green stone.

Hampden and Hampshire Counties. — A fine-grained, dark gray,
quartz-diorite gneiss found near Monson is used chiefly for building and
curbing. The banding is attributed to flow structure rather than to
metamorphism. A gneissoid granite similar to the Monson, quarried in
a small way at Pelham, has been used principally for local building.

Middlesex County. — A light bluish gray biotite-muscovite granite
gneiss (more properly a quartz monzonite), quarried near Acton, is used
chiefly for building and curbing. Coarser grained granites from the
vicinity of Groton are used chiefly for paving stones.

Important deposits occur near Graniteville, Westford, West Chelms-
ford, and Lowell. The ''Oakhill," from the neighborhood of Westford,
is a light bluish gray muscovite-biotite granite gneiss. It is medium-
grained and slightly porphyritic. Sheets are 8 inches to 12 feet thick.
Joints are in three main systems intersecting at oblique angles. The
rift is horizontal and the grain vertical. The best-quality rock is used
for monuments and dressed building stone, and the coarser and less
uniform material for bridges, rough building stone, paving blocks,
curbing, and rubble. The ''Graniteville" is similar, though generally
lighter in color. About a dozen companies, some with extensive quarries,
operate in the West Chelmsford- Westford district. The largest quarry
at West Chelmsford is about 1,500 feet long, 500 feet wide, and 100 feet
or more deep. Sheeting planes are horizontal, and sheets are progres-
sively thicker at depth. Vertical joints are widely spaced. The quarry
is exceptionally well-equipped for production of building stone, curbing,
and paving stones.

Norfolk County. — The granite industry in the neighborhood of
Quincy is one of the most important in the United States. The rock
occurs 7 or 8 miles south of Boston in the Blue HiUs, a ridge which attains

GRANITE 119

a maximum height of about 640 feet. The quarries are in a lenticular
area about 10 miles long from east to west, and one half to 2 miles wide.
The rock is of unusual composition, being described as a riebeckite-
aegirite granite. Riebeckite and aegirite are varieties of amphibole and
of pyroxene, respectively, both rich in soda and iron but low in alumina,
magnesia, and lime. Average Quincy granite consists of about 60
per cent feldspars, 31 per cent quartz, and 9 per cent riebeckite and
aegirite. Unlike most granites it contains no mica. In color it ranges
from medium or greenish gray to dark bluish gray. The bluish shades
probably are due to the presence of the riebeckite and the greenish color
to the aegirite. It is a medium- to coarse-grained rock of uniform texture
and is noted for its ability to take a high polish. The darker varieties
are marketed, chiefly as rough monumental stone, to manufacturers who
distribute it to retail monument dealers in all parts of the country.
The various trade names are "Quincy Medium," "Quincy Dark,"
"Quincy Extra Dark," and "Goldleaf." The last is the lightest shade
of monumental stone sold, and is characterized by yellowish and reddish
specks of iron oxide derived in part from oxidation of the unusual mineral,
aenigmatite. "Extra Light" or "Pea-Green" are even lighter colored
varieties, used principally for building.

Sheet structure is well-defined in places, the planes ranging in spacing
from 6 inches to 27 feet. The sheets consist of lenses with an undulating
course, usually parallel to the rock surface, and with increasing thickness
at depth. Planes have been found at a depth of 250 feet. In other
parts of the deposit the sheeting is obscure and irregular. Joints are in
several systems, meeting at various oblique angles. As their course is
followed downward many disappear, and new ones may appear at various
levels. Such discontinuity is characteristic of the Quincy district.
The spacing of joints is very irregular, ranging from 1 or 2 to over 100
feet. Another unusual feature is the presence of rift and grain, both in
vertical directions. Generally the course of the rift is from N.65°W.
to west, and the grain is about north and south, though there are excep-
tions. Frequently the grain is obscure. Trap dikes and black knots
occur in places.

The Quincy granite industry first became important in 1825, when
stone for Bunker Hill monument was quarried. For many years five to
eight companies have been in operation, and the annual value of their
combined product has been $370,000 to $675,000.

Granite is produced in several places in Norfolk County outside the
Quincy district. In the extreme east, near Cohasset, a mottled yellowish
gray granite of coarse texture is quarried for monuments and church
interiors.

At Weymouth, south of Quincy, a gray granite is sold for decorative
ashlar and rough masonry. The walls of the closely spaced joints are

120 THE STONE INDUSTRIES

stained yellow and brown, providing variegated colors for seam-faced
stone now so popular with architects. A coarse-grained gray stone
quarried near Stoughton is used for local building. A light gray, medium-
grained hornblende granite from Wrentham is used for building and
curbstones.

Plymouth County. — At Hingham, in the northeastern part of the
county, a greenish gray aplite is quarried for building purposes. Few
sheeting planes occur, but joints are numerous and closely spaced. As
the rock is stained to a rusty color in the numerous seams it is not suitable
for monumental work but fulfills modern demands for decorative building
admirably. Like the rock near Weymouth, described in the preceding
paragraph, it is marketed as seam-faced granite and has been used in
many notable buildings. Stone for similar uses is obtained near Lake-
ville in the southern part of the county.

Worcester County. — The most important granite district of Worcester
County is near Milford, about 16 miles southeast of Worcester. Between
15 and 20 quarries have been opened in various parts of this extensive
deposit. The Milford rock is a light pinkish or greenish gray biotite
granite characterized by black spots of mica. It is of medium to coarse
texture, with a slight tendency toward banding or parallelism which is
attributed to flow structure. When the rock is cut parallel with the flow
structure the black spots are largest, because the mica flakes parallel
this direction. Another characteristic feature is the blue color of the
quartz grains. The rock is cut by diorite, aplite, and porphyritic granite
dikes. Black knots are present in places, some being inclusions and some
segregations. Sheeting planes are 6 inches to 18 feet apart. Joints are
in three main systems N.10°E., N.45°-60°E., and N.55°-70°W.; though
they are also found in other directions. The rift is uniformly horizontal
and the grain vertical, ranging in direction from N.40°E. to east-west.
''Milford Pink," the prevailing commercial type, has a pleasing color,
either with tool-dressed or polished surface, and is particularly effective
for carved or other architectural work. It has been used in many large
buildings in the Eastern and Middle Western States, notably in the
Pennsylvania Railroad station in New York.

At Uxbridge, about 8 miles southwest of Milford, a light gray,
medium-textured biotite granite gneiss, useful for construction purposes,
is quarried. Though sheets are absent, joints are numerous. Alteration
or staining from the joint surfaces forms the so-called "sap" rock to a
depth of a foot in places. The stone is used for rough construction,
dressed building stone, curbing, and rubble and to some extent for
monuments.

Near Fitchburg in the northern part of the county a light bluish gray
muscovite-biotite granite gneiss is quarried for building stone, paving
blocks, and curbing. A little rough construction stone is obtained at
Holden, near Worcester.

GRANITE 121

Minnesota. — Minnesota, which ranked third in production, has
deposits of high-grade granites of several distinctive types. The major
part of the industry is centered near St. Cloud, in Stearns and Sherburne
Counties, about 60 miles northwest of Minneapolis. St. Cloud ranks
second as a national monumental granite center, being exceeded in value
of output only by Barre, Vt.

The value of dimension granite produced in Minnesota in 1928 was
$2,637,704, or 10.6 per cent of the total for the United States. Corre-
sponding figures for 1929 are $3,226,665; for 1930, $2,648,909; for 1936,
$1,205,688; and for 1937, $883,179. Building-granite production is a
much more important industry in Minnesota than in Vermont, as about
40 per cent of the output is used for construction and 60 per cent for
monumental purposes. Paving-block and curbing production have
become almost negligible in recent years.

Minnesota granites occur in two main districts. Those usually classed
as of lower Keweenawan age outcrop in many parts of central Minnesota,
notably in Stearns, Sherburne, Benton, Morrison, and Millelacs Counties;
in the southwestern part of the State, along the Minnesota River Valley
from New Ulm to Ortonville, those of Archean age occur. Granites
appear in other counties but are not considered here, as they are utilized
to a very limited extent as dimension stone. Recently a small production
of monumental and rough building stone has been reported from St.
Louis County in the far north.

As the granites occur in two distinct areas it seems more logical to
consider each separately than to discuss the occurrences alphabetically
by counties.

St. Cloud District. — Granites occur at or near the surface over an area
of about 200 square miles near St. Cloud, "the Granite City." The
most active quarry region, in which 25 to 30 companies operate, is 3 to 4
miles west and southwest of the city. Many well-equipped mills for
cutting and polishing are situated in St. Cloud; and, unlike those of the
Barre district of Vermont, most of the mills are operated by quarry
owners. Therefore Minnesota products enter the market as cut or
dressed stone, whereas much of the Vermont production is sold in rough
blocks. On this account, the unit value of the Minnesota stone is much
higher than that of the Vermont product.

The rock is of three main types, "St. Cloud Red," "St. Cloud Gray,"
and "Rockville." The red granite is medium- to coarse-grained, the
feldspars averaging about one fourth inch in diameter. These minerals,
which constitute about 75 per cent of the rock, consist of orthoclase and
microcline with a smaller amount of plagioclase. Quartz, forming about
15 to 20 per cent of the rock, occurs in coarse glassy grains. Hornblende
and biotite form 5 to 10 per cent. The rock is deep red, is very attractive
when polished, and is therefore used chiefly for monuments. The gray
granite consists principally of orthoclase, plagioclase, hornblende, and

122 THE STONE INDUSTRIES

quartz, the last mineral being much less prominent than in the red
granite. It is used chiefly for monuments, though a subordinate amount
is used for paving blocks and curbing. "Rockville" is much coarser-
grained than the red and gray types, the feldspars being one half to three
fourths inch across. It is a pinkish gray biotite granite, consisting of
feldspar, chiefly orthoclase, quartz in large glassy grains, and black mica.
Though used for monuments to some extent, it is essentially a building
granite.

The deposits are cut by granite, aplite, and trap dikes. In many
places red granite dikes cut the gray, while the converse is never found,
indicating that the red granite is a later intrusion. Aplite dikes are
common, especially in the gray granites. Diabase or trap dikes, occurring
in many places throughout the region, range in width from a fraction of an
inch to 6 or 8 feet. Hair lines of various types are present. Black
knots, both segregations and inclusions, are not abundant but are fre-
quent enough to be troublesome. As stated earlier, joints are well-
developed, usually in two major systems, one running approximately
north and south and the other east and west. They are spaced at
convenient intervals for quarrying, usually 2 to 12 feet apart. Sheeting
planes are scarce or entirely absent, a circumstance which makes quarry-
ing difficult. The rift is horizontal and the run vertical, ordinarily
north and south.

Stearns County. — The chief quarry district is in western St. Cloud
township, where 15 to 20 quarries are in operation. Both red and
gray granites are quarried. The rock occurs in a series of low domes
which may be worked as shelf quarries of shallow depth, but most of the
quarries are deep enough to be of the pit type. The rift and run are more
pronounced in the gray than in the red, on which account the former is
better adapted for paving stones and curbing. For monumental uses
the deep reds are more desirable. Quarrymen have their own special
trade names, among which may be mentioned "Rose Red St. Cloud,"
''Indian Red St. Cloud," "Victory Red St. Cloud," "St. Cloud Superior
Red," "Red Rock," "Melrose Red," "Minnesota Mahogany," "Black
Diamond Red," "Red Pearl," "North Star Red," "St. Cloud Gray,"
"Victory Gray St. Cloud," "St. Cloud Superior Gray," "Melrose
Gray," "Pioneer Gray," "Royal Gray," and "Dark Gray." The
granites are much in demand and are widely marketed, even in States far
from the quarries.

The Rockville district is about 10 miles southwest of St. Cloud in a
pale pink coarse-grained granite of exceptionally uniform texture and
color. The rock rises in a dome which is exposed over at least an acre.
Open joints are far apart and somewhat irregular in direction. The most
prominent strike N.70°W. ; others strike N.45°E., N.55°W., and N.10°W.
If joints were closely spaced, this irregularity would result in much

GRANITE 123

waste rock, but here where they are spaced 20, 40, and even 100 feet apart
the irregularity has httle consequence. In fact, quarrying would be
much easier if they were spaced more closely. There are also few
sheeting planes. The rock is so uniform and so free from defects that
very little waste results. "Rockville" granite is an attractive structural
stone, for the cleavages of the coarsely crystallized feldspars give a
glittering reflection on the hammered surface. It is also well-suited for
carving, but is used to a limited extent for monuments. The granite is
quarried by two long-established companies and is sold under the trade
names ''Minnesota Pink" and "Minnesota Pearl Pink." It has been
used in many notable buildings, for example, in the cathedral at St. Paul,
Minn.

Sherburne County. — Granites are available only in the northwest
corner of Sherburne County. Though red and some intermediate
varieties are present, gray predominates. The gray rock has a horizontal
rift and vertical run (grain) north and south. Black knots and aplite
dikes occur in places. Most of the joints are widely spaced. In some
quarries sheeting planes are 4 to 16 feet apart; in others few are encount-
ered. The rock is adapted chiefly for building and for paving blocks.
One large quarry is operated by the State reformatory, and the rock is
used for construction of the main building and walls. Several companies
operate in both red and gray granite, producing building stone, paving
blocks, curbing, and monument stock. During recent years, however,
paving and curbing manufacture have decreased greatly. "Minnesota
White" and "Hilder Gray" are common trade names.

Benton County. — Outcrops are more numerous in Benton than in
Sherburne County, but the rocks are less uniform and present a greater
diversity of types. The most abundant rock is a dark diorite some of
which has been used for building stone, paving blocks, and monumental
stock.

Mille Lacs County. — On the west branch of Rum River a few miles
west of Milaca a red granite is quarried for monuments and sold under
the name "Sunset Red." Most of the rocks in the county are diorites
and are not attractive for high-grade work.

Morrison County. — A granite of the "St. Cloud Red" type is quarried
near Glenola for manufacture of monuments. A dark, fine-grained rock
quarried near Little Falls is described as an augite-diorite, consisting of
numerous lathlike crystals of plagioclase, biotite, green hornblende, and
almost colorless augite. It is marketed as a black granite under the trade
name "Little Falls Black."

The Granites of the Minnesota River Valley. — Thousands of years ago
an immense volume of water derived from melting ice sheets and from
rainfall over an area that may almost be termed continental poured down
the valley of what is now the Minnesota River. In its passage it swept

124 THE STONE INDUSTRIES

away all decayed and weathered debris and eroded a valley 2 miles wide in
places, a valley entirely out of proportion in magnitude to the small
river that now flows through it. Ancient Archean rocks ordinarily
protected by a covering of Cretaceous sediments, are exposed in this
valley; and not only have overlying formations been removed, but the
scouring effect of the great river has swept away the upper zone of
weathered granite, leaving the rock fresh and unaltered at the surface.
Both granite and granite gneiss outcrop in many places, and have been
quarried at various points between Odessa and Morton.

Big Stone County. — There are numerous outcrops near Ortonville,
Odessa, and Correll. The " Ortonville " stone is a deep red biotite granite
or granite gneiss, which takes an excellent polish. In quarrying, much
waste results from the presence of pegmatite dikes, black knots, and
closely spaced or irregular joints. Monumental stone and ornamental
columns sold as "Ruby Red" have been obtained from these deposits.

Redwood and Renville Counties. — The best rock in these counties occurs
in outlying masses in the Minnesota River Valley. These are prominent
domes at North Redwood and across the river from Morton; near the
latter town a dome covers many acres and reaches an elevation which
affords an extensive view of the river basin from its summit. The rock
exhibits little or no weathering, even at the surface. Two types are
available near North Redwood — one a medium-grained, greenish gray
biotite gneiss, and the other a pale pink biotite granite or quartz diorite.
Both rocks are even-grained and are exceptionally attractive for monu-
mental and building uses. A type known as "Rainbow" granite is well
known in the monument trade.

The rock near Morton is a biotite granite gneiss with distinct banding.
Although of uneven texture it takes a good polish, and about half of the
production is suitable for monumental stone. It is also used for monu-
ment bases, curbing, building stone, and bridge construction. It is
very strong, even in a direction parallel to the banding. Sheeting planes
are 12 to 20 feet apart and dip 5 to 15°, always toward the margin of the
dome. Major joints are 6 to 30 feet apart, in systems approximately at
right angles. Black knots and streaks are present in places. The
strength of the rock and its availability in large sound blocks make it
particularly suitable for heavy construction.

North Carolina. — The value of block granite produced in North
Carohna in 1928 was $2,253,435, or 9.1 per cent of the total for the
United States. As in Massachusetts, the production is diversified; 43.7
per cent of the total for the year was building stone, 15 per cent monu-
mental stone, 13.7 per cent paving blocks, 26.2 per cent curbing, and 1.4
per cent rubble. Building granite has become increasingly important
in North Carolina since 1926, the growth in volume being due to the
increased use of ashlar granite in medium-priced dwellings. So much of

GRANITE 125

the production was "undistributed" in the years 1929 to 1937 that
figures obtainable do not give a true picture of the extent of the industry.

Granites and gneisses are distributed widely in the State, being found
in all three of the larger geologic provinces— the Coastal Plain, the
Piedmont Plateau, and the Appalachian Mountains. Those that have
been used most are in the Piedmont Plateau region.

Granites occur in several counties of the Coastal Plain in the region
bordering the Piedmont Plateau, and are extensions of the crystalline
rocks of the latter region beneath the Coastal Plain sediments. They
range from fine even granular to coarse porphyritic in texture and from
gray to pink in color. Most of them are biotite granites. Joints
are well-developed in three main systems, northwest, north, and
northeast. Diabase dikes are of common occurrence.

Much stone of good quality is readily available within the limits of
the Piedmont Plateau. Numerous quarries have been worked over
many parts of this region, which has been divided geologically into four
belts. The northeastern area, including Wake, Franklin, Vance, Gran-
ville, and Warren Counties, borders the Coastal Plain. Most of the
granites in this section are schistose and therefore have limited commercial
value. In certain areas, however, granites of good quality for building
purposes have been worked for many years. The next belt to the west
consists of slates, schists, and altered volcanic rocks, with little or no
granite of commercial value. West of this is the central belt, including
Mecklenberg, Gaston, Cabarrus, Iredell, Rowan, Davidson, Davie,
Forsyth, Guilford, and Alamance Counties, where biotite granite is one of
the principal and most widespread rocks. It occurs in each of the 10
counties mentioned and has been quarried from time to time, usually to
satisfy local demands. Two distinct types occur, an even granular rock
and a porphyritic granite, much of which shows evidence of gneissic or
schistose structure. Colors range from white to various shades of gray
and occasionally pink. The western belt includes Surry, Wilkes, Alle-
ghany, Alexander, and Cleveland Counties, with greatest development in
Surry County. This area is well-supplied with railway lines, which
greatly aid marketing. The commercial granites here are in the form of
igneous intrusions of both massive and schistose types.

The Appalachian belt is mountainous, and quarrying has been
confined chiefly to a few areas of gneiss suitable only for crushing or for
rough construction. In Madison County an area of mixed dark green
and yellow biotite-epidote granite should prove of economic value.

The commercial granites will be considered in the three geologic
provinces in succession:

Coastal Plain Granites, wilson county. — Only small areas of granite
are exposed in Wilson County, the more important about 3 miles north
and 3 miles south and southwest of the town of Wilson. During recent

126 THE STONE INDUSTRIES

years the latter area, with exposures on both sides of Contentnea Creek, is
the only one quarried. The rock is coarse-grained, pinkish red and of
porphyritic texture. It is used for bridge construction and rough
building.

While granites occur in other Coastal Plain counties little or no
block granite has been produced in late years.

Piedmont Plateau Granites. — surry county. — The most important
granite district of North Carolina is near Mount Airy in Surry County
near the northern boundary of the State, Originally the outcrop was a
dome rising about 125 feet above the valley, but much of the upper part
has been removed. The surface area, now exposed partly as a natural
outcrop and partly by stripping, covers about 70 acres. The rock is a
very light gray, almost white, biotite granite of medium texture. The
biotite is unequally distributed; some masses contain little or none, in
consequence of which they are exceptionally white. For the most part,
however, the rock is of uniform color and texture. Veins and dikes, so
common in most granites, are nowhere evident in the Mount Airy deposit.
Absence of joints and sheeting planes is the most remarkable feature,
the rock being massive throughout, with no natural partings. It has a
horizontal or slightly dipping rift and a vertical grain — structural
features of the utmost importance in quarrying and manufacture.

Production has grown steadily since 1890, when the rock was first
quarried. Operations are now more extensive than in any other district
south of New England. The rock has exceptional merit for building
purposes and for mausoleums, as it is light in color and pleasing in
appearance, and also for bridge work, as sound blocks of any desired size
are obtainable. Granite from this deposit valued at $1,500,000 was used
in the Arlington Memorial Bridge over the Potomac River at Washington,
D, C, shown in the frontispiece. It has been employed in many large
structures throughout a wide market area extending to Philadelphia,
New York, and more distant cities. Although the chief market is for
cut stone used in bridges, dry docks, and large buildings, quite an exten-
sive market has been developed recently for the smaller fragments in the
form of ashlar for constructing moderate priced dwellings. Such material
is being shipped as far north as eastern Pennsylvania. Mount Airy
granite is also well-adapted for the manufacture of paving stones and
curbing, and the latter use accounts for about one fourth of the total
production value. It is less suitable for monuments, as the color contrast
between cut and polished surfaces is not decided enough. Both quarries
and mills at Mount Airy are equipped with the most modern machines
and appliances,

ROWAN COUNTY. — Next in importance to the Mount Airy granite are
those found near Salisbury, Rowan County. The rock rises in a nearly
continuous ridge, beginning about 4 miles east of Salisbury and extending

GRANITE 127

southward more than 12 miles. In the northern part two distinct types
occur, a very Hght gray or nearly white rock, and a pink or flesh-colored
granite. They are of identical texture and mineral content and evidently
parts of the same intrusion. In the pink rock quarried near Granite
joints are in two systems striking N.10°E. and N.70°W., and are spaced
widely enough to permit quarrying large blocks. Sheeting planes are 2
to 8 feet apart. The rock is notably free from veins or dikes, is medium-
grained, uniform in texture, and attractive in color. It is sold both rough
and dressed and is popular as a monumental stone marketed under the
trade name "Balfour Pink."

In the gray rock, also quarried near Granite, joints are less systematic
than in the red but are widely spaced. The stone has good working
qualities and dresses well under the hammer. It has been used widely
as a building stone and for curbing and paving but little for monuments.
Similar granites, both gray and pink, are quarried near Faith, 5 to 9 miles
south and southwest of Salisbury.

DAVIDSON AND WAKE COUNTIES. — Gray granites of various types occur
in Davidson County, but in recent years they have been quarried only in
the vicinity of Southmount and used chiefly for paving blocks. In the
vicinity of Wake Forest in the northern part of Wake County a medium-
to fine-grained, light gray biotite-muscovite granite is quarried for build-
ing, curbing, paving blocks, and rubble.

Appalachian Mountain Granites. Henderson county. — A medium-
grained, light gray biotite gneiss occurs near Hendersonville, It is of
uniform color and texture, though a few black knots occur in places.
Large blocks are obtainable. Most of the granite quarried in Henderson
and in Buncombe County to the north is used for crushing, though it is
used to some extent in rough construction.

Maine. — The value of granite in the form of dimension stone produced
in Maine in 1928 was $2,249,715 or 9.1 per cent of the total for the
United States. Paving stones, which represented 54.8 per cent of this
amount, are the chief products. Maine produced more than 42 per cent
of all the granite paving blocks in the country. The value of building
stone was 25.2 per cent, monumental stone 6.9 per cent, curbing 12.9
per cent, and rubble 0.2 per cent of the total. There is evidence of a
trend toward a larger percentage of building-granite production, as the
location of quarries at the coast is favorable for water transportation to
New York and other coast cities, where it is gaining in popularity.
Production in 1929 was valued at $2,630,266; in 1930, $2,039,058; in 1936
$1,212,855; and in 1937, $1,280,122.

Granite is distributed widely in Maine ; in fact, it is the most abundant
rock. It occurs in three main areas — in the western tier of counties,
along the eastern coast, and in the Mount Katahdin area in the north-
central part. In addition, there are three small areas in Lincoln, Ken-

128 THE STONE INDUSTRIES

nebec, and Somerset Counties. Except for important centers at Hallowell,
Kennebec County, North Jay, Franklin County, and several develop-
ments of minor importance, all quarries are along the seaboard, either on
or within a few miles of navigable waters. The industry is centered in
Penobscot and Bluehill Bays and the islands in or adjacent to them.
Occurrences now of commercial importance will be described by counties
in alphabetical order,

Cumberland County. — A fine, even-grained gray biotite granite is
quarried about 33^^ miles northeast of Westbrook. It has a distinct flow
structure which gives it the appearance of a gneiss. Sheeting planes are
6 inches to 2}^ feet apart and nearly horizontal. Joints are few, and the
rift is horizontal and grain vertical, striking eastward. The rock is used
for monuments and curbing.

Franklin County. — An important granite center of the county, par-
ticularly for building granite, is at North Jay. The rock, a light gray
biotite-muscovite granite of fine, even-grained texture, is known to the
trade as "North Jay White." The whiteness is due to the quartz being
clear, not smoky as in many granites, and to the light color of the feldspars
visible through the quartz, as well as on the surface. The sheets are 4
inches to 6 feet thick, being quite thin in the upper 25 feet and gradually
thickening at increasing depths. The chief joints run N.62°E., N.70°E.,
and N.50°W. and are widely spaced. The rift is horizontal, and there is
no grain. Black knots are rare, but a few pegmatite dikes are present.
The rock is exceptionally attractive for building, though it is also used
extensively for monuments, mausoleums, paving stones, and curbing.
Though one of the few important granite centers of Maine distant from
tidewater, it has direct rail connection, and its products are widely
employed not only in New York, Philadelphia, and other eastern cities
but also throughout the Middle West.

Hancock County. — More granite is produced in Hancock than in any
other county in Maine. Over a dozen quarry companies operate near
Franklin. The rock is a medium- to coarse-grained, gray biotite granite,
of uniform texture. Sheeting planes are 2 to 13 feet apart. For the
most part, joints are widely spaced. The rift is horizontal and grain
vertical, usually striking east-west. Black knots and trap dikes are not
unusual. Paving blocks, curbing, and monument bases are the chief
products.

A light buff to gray biotite granite of medium to coarse, even-grained
texture is quarried near Mount Desert. The four chief minerals — buff
orthoclase, milk-white plagioclase, smoky quartz, and black biotite —
present very attractive color contrasts which are enhanced by polishing.
In one part of the deposit the rock is pinkish gray and is marketed as
"Sommes Sound Pink." Sheets are 2 to 12 feet thick. Widely spaced
major joints strike N.25°W., N.50°E., and N.85°E. The rift is horizontal,

GRANITE 129

and grain vertical, usually striking east-west. Dark gray knots up to 6
inches in diameter occur in places. The quarries are close to tide-water,
and the wharves are accessible to schooners of 20-foot draft. Building
stone, monument stock, and paving stones are the chief products. The
stone has a wide market and has been used in many important structures.

Another important quarry district covers an area of about 4 square
miles around Stonington, including parts of Deer Isle and Crotch Island.
On the southern half of the latter island the rock rises in a dome about 140
feet above sea level. At its center the sheets are horizontal but dip
downward at angles of 10 to 25° toward both the northwest and the
southeast. East- west vertical joints are prominent. The Crotch Island
rock, a coarse, even-grained, gray biotite granite with lavender tint, is
well-suited for massive construction. Its polished surface shows pleasing
contrasts, and on this account it is in demand for base courses, wainscot-
ing, and monuments.

An important deposit of similar granite occurs on Deer Isle and is
quarried about 2 miles from Stonington. Sheets are 6 inches to 16 feet
thick and dip 10 to 15° north and south, away from the top of the hill.
Joints are widely spaced, the rift is vertical and runs N.60°-65°W., and
knots are rare and small, but granite dikes 4 to 12 inches thick occur in
places. The stone is used widely for massive construction, such as for
piers, sea walls, and bridges and also in many large buildings.

Near Sullivan a fine- to medium-grained, uniform gray biotite granite
is quarried. The sheets in one quarry are 3 to 8 feet thick. Joints
strike N.80°-85°W. and N.10°-20°E. There are many black knots. In
another quarry the sheets are only 1 to 5 feet thick. A coarse- to medium-
grained gray granite is also quarried in this district. Paving blocks and
curbing are the chief products. Similar granites are quarried for monu-
ment bases, paving blocks, and curbing near North Sullivan.

Kennebec County. — An important inland stone-producing district near
Hallowell is one of the oldest in the country, the quarries first having
been opened in 1826. Though a considerable distance from the coast,
they are only 2}-^ miles from a wharf on the Kennebec River and are
accessible to schooners of 12-foot draft. The well-known, fine-textured,
light gray "Hallowell granite" consists essentially of feldspar, quartz,
biotite, and muscovite. The most striking structural feature of the
quarries is the gradual increase in thickness of the sheets downward, from
4 inches to 14 feet. Joints are spaced more closely than in many New
England granites and intersect the rock at various angles. The rift is
horizontal, and a poorly developed grain vertical, striking N.25°W.
Black knots occur in places, and sap rock bordering the joint planes may
be a foot deep. The stone is widely used for building purposes, where it
is particularly adapted to carving, and also for monuments and paving
stones.

130 THE STONE INDUSTRIES

Knox County. — The principal quarries of Knox County are near
Long Cove, St. George, and South Thomaston, south and southwest of
Rockland, and on Vinalhaven Island. In the former region most of the
rock is fine- to medium-grained and blue-gray. Sheeting planes are 2 to
13 feet apart and usually dip at small angles. Joints vary in direction
and are closely spaced in places. The rift is vertical, with a general east-
west course. Many paving blocks are made and as the stone takes a
good polish it is popular also for monuments.

Vinalhaven and the adjacent islands have been known as the Fox
Islands, and their granite as " Fox Island Granite." Many quarries have
been operated at various times, chiefly near Vinalhaven Island and on
Hurricane Island. During recent years two companies have been
responsible for the chief production. Much of the rock is pinkish buff
and coarse textured, but some quarries produce a fine, even-grained, gray
granite. In this rock sheets are 1 to 6 feet thick; vertical joints strike
N.80°W. and N.5°-10°E. The rift is vertical, striking N.5°-10°E. In
the coarse rock, sheets are 2 to 10 feet thick, and the joints are in several
intersecting systems. Although building stone has been produced from
these quarries, recent production has been confined principally to paving
stones. An attractive black granite is quarried at Vinalhaven.

Lincoln County. — A fine-grained dark gray quartz diorite, classed
commercially with the "black granites," is quarried near Round Pond
for monuments and paving blocks. Sheets are 1 to 12 feet thick. Major
joints striking N.60°E. are 5 to 40 feet apart, and a second system
N.40°W. is at wider intervals. The rock is cut by both pegmatite and
trap dikes. It takes a good polish and shows marked contrast between
tooled and polished surfaces.

Somerset County. — A light gray, even-grained granite with a distinct
flow structure has been quarried at several points about 2}^ miles south
of Norridgewock. It is used for both buildings and monuments.

Waldo County. — A fine- to medium-grained, light gray, muscovite-
biotite granite is quarried near Lincolnville, chiefly for monumental use.
The sheets are 6 to 15 feet thick and dip 25°S. The chief joints strike
N.60°-65° W. The rift is vertical and parallels the major joints. Quarries
at Mt. Waldo near Frankfort, which had been idle 25 years, were reopened
in 1930 and equipped to produce building granite on a large scale. The
rock is a fine, even-grained, gray biotite granite. Stone from these
quarries was used extensively in the George Washington Bridge at New
York. Water transportation on the Penobscot River is available.

Washington County. — Washington County granites are of two main
types— ''black granites" and medium-grained pinkish gray biotite
granites. Some of the so-called black granites are norites but that
quarried near Addison is a gabbro which poHshes to a jet-black surface
mottled with a little white, and one occurring near Calais is a dark gray

GRANITE 131

quartz diorite. As they all take a good polish, they are used for monu-
ments. The pink granites, one of which is sold under the trade name
"Back Bay Pink," quarried near Marshfield and Millbridge are used for
monuments and building.

York County. — A coarse-grained, light gray granite occurs near
Biddeford in sheets 1 to 15 feet thick. The rift is vertical, and the grain
horizontal. It is used for monuments and rough construction. "North
Berwick Black Granite" (gabbro) quarried near North Berwick is well
adapted for monuments.

Georgia. — Block granite produced in Georgia in 1928 was valued at
$1,985,838, or 8 per cent of the value of total production for the United
States. About 26 per cent was sold as building stone; 21 per cent,
monumental; 19 per cent, paving blocks; 33 per cent, curbing; and 1 per
cent, rubble. Although fluctuations have occurred the trend in produc-
tion was gradually upward from the World War until 1928. Production
in 1929 was valued at $1,741,938; in 1930, $1,673,529; in 1936, $920,355;
and in 1937, $875,529.

The granites of Georgia are entirely within the limits of the Piedmont
Plateau, a northeast-southwest belt extending from the eastern base of the
Appalachian Mountains to the Coastal Plain sediments occupying the
middle-northern part of the State. Dimension stone is produced in
three main districts — in the vicinity of Stone Mountain and Lithonia in
De Kalb County, near Elberton in Elbert County, and near Sparta
in Hancock County.

De Kalb County. — The most notable occurrence of granite in Georgia
is Stone Mountain in eastern De Kalb County. It is a massive dome
measuring 7 miles in circumference at its base and rising 686 feet above
the adjacent lowlands. The rock is an even-textured, medium-grained,
light gray muscovite-biotite granite of uniform color and texture. Joints
in two well-defined systems, striking northeast and northwest are widely
spaced, as are also the sheeting planes. The granite is well-adapted for
building purposes and for bridges and mausoleums, as it is available in
sound blocks of any desired size. Paving blocks, rubble, and a limited
amount of monument stock are also produced. A wide market has been
developed for the stone in Northern and Middle Western States, as well
as in Atlanta and other adjacent cities. One large company has operated
for many years on the flank of the dome.

A project to carve in massive proportions high on the cliff face a
group of great Confederate generals has created much interest in Stone
Mountain during recent years. The actual carving was begun in June
1923, but work was suspended 3 or 4 years later with the task far from
completed.

In the Lithonia district the rock a fine-grained, highly contorted
biotite granite gneiss, occurs in similar bosslike masses, though much

132 THE STONE INDUSTRIES

smaller than Stone Mountain. Red garnet and tourmaline are present
in places, the latter mineral being associated with pegmatite dikes. In
some quarries well-defined joint planes appear, while in others they are
few in number. Sheeting planes are absent. The rock has a distinct rift
and grain which are of great assistance in quarrying. Eight or ten com-
panies have worked the deposits for many years. The chief products, pav-
ing stones and curbing, are sold in Atlanta and other southern cities and
also shipped to many distant points. Rubble is produced as a byproduct.

Elbert County. — Granite is confined chiefly to the middle southwestern
part of the county, though it extends into adjacent counties. In many
places the rock appears in bare outcrop. There are two main types — a
fine- to medium-grained, light gray, biotite granite and a dark blue-gray
granite similar to the first, except in color. The former is best adapted
for building purposes. The blue-gray granite is so uniform in texture
and attractive in color and general appearance that it is used widely as
monumental stone. Several companies operate in the district and
market their products under various trade names, such as "Elberton
Blue," "Oglesby Dark Blue," and "Oglesby Light Blue." Red or pink
granites occur less commonly. One commercial variety is sold under the
trade name "Sunset Pink." Railway facilities are available for ship-
ment to many distant markets.

Hancock County. — The Hancock County granite area is about 11
miles long and extends northeast from Sparta. The rock occurs in bare
outcrops, some several acres in extent. The prevailing type is a coarse-
grained, medium gray, porphyritic biotite granite used for curbing,
paving stones, and monuments.

Wisconsin. — The value of Wisconsin block granite produced in 1928,
as reported to the United States Bureau of Mines, was $1,581,612, or
6.4 per cent of the value of total production of the United States. Nearly
three fourths of the product in value is sold for monuments and one
fourth for paving blocks. The proportion by uses was as follows in 1928 :
Monumental stone, 72.9 per cent; paving blocks, 24.9 per cent; building
stone, 1.7 per cent; and curbing, 0.5 per cent. Production in 1929 was
valued at $1,572,010; in 1930, $1,327,913; in 1936, $673,846; and in
1937, $794,578. Paving-stone production fluctuates greatly from year
to year, with a general downward trend.

Igneous rocks underlie about one third of Wisconsin. Throughout
this area granites of many colors and textures are found, and several dis-
tinctive varieties are marketed. Dark reds and reddish browns predomi-
nate, a condition that contrasts sharply with the prevailing grays of New
England. The granites are described by counties in alphabetical order.

Ashland County. — A dark gabbro is quarried near Mellen. It takes a
good polish and is sold for monumental and building uses as "black
granite."

GRANITE " . 133

Green Lake County. — Rhyolite is quarried near Berlin, Green Lake
County. Joints and sheeting planes are numerous and intersect at
various angles, which results in the production of many small angular
blocks, though large blocks are available. The rift is nearly horizontal
and the "run" (grain) vertical. The rock polishes well on the run and
hard way but not on the rift surfaces. It is dense and compact, of uni-
form texture, and generally grayish black. "Berlin rhyolite" is strong
and durable and is used for monuments, paving blocks, and building stone.

Marathon County. — The widely known "Wausau Granite" outcrop-
ping at numerous places over an area of many square miles is quarried at
Wausau and Granite Heights. The rock now quarried is not uniform in
color but ranges from gray through reddish brown to brilliant red. Major
joints are in two systems, striking approximately northeast and north-
west. Sheeting planes are horizontal. Sound blocks of large dimensions
are obtainable in most quarries, though in some places joints are less than
4 feet apart. It is used almost exclusively for monuments and sold
under various trade names, such as "Wisconsin Mahogany," "Red
Wausau," "Wisconsin Ruby Red," and "Parcher Green."

Marinetta County. — Granite in a variety of textures and colors is
quarried along the Pike River near Amberg. Three distinct types are
produced — a fine-grained, gray granite (Pike River Gray), a coarse-
grained, red or pale pink (Amberg Red), and a coarse-grained gray. In
general the joints are spaced far enough apart to provide suitable monu-
ment stock, but in some places are undesirably close together, or intersect
at oblique angles. The rift is indistinct. In the past considerable
building stone was produced, but during recent years monument stock
is the chief product with a subordinate amount of paving stones. " Mont-
rose Red" and "Marinetta Red" are other trade names applied to the
products.

Marquette County. — High-grade granite is obtained from two mounds
near and within the city of Montello. In the larger quarry, prominent
joint systems strike N.85°E., N.25°E., and N.40°W. Many discontinu-
ous parting planes break the rock into polygonal blocks, but masses of
reasonable size for monuments are obtainable. Several greenstone dikes
(trap) follow jointing planes. Streaks or hair lines which mar some of
the rock are of two types, minute trap dikes and white quartz veins.
The rock is a dense, fine-grained granite in two colors, a cheerful bright
red and a grayish red. "Montello Granite" is a widely known, popular
monumental stone. It takes a good polish and is attractive, but is
difficult to work. Paving stones are manufactured, though not so
extensively as in former years.

Waupaca County. — A coarse-grained or porphyritic biotite-hornblende
granite of striking color and texture is quarried about 5 miles north of
Waupaca. The two more important commercial types are "Red

134 THE STONE INDUSTRIES

Waupaca" and "Gray Waupaca." The former consists of large, bright
pink feldspars surrounded by green epidote and chlorite, and the latter
is a combination of paler pink feldspars, black biotite, and hornblende.
Numerous, irregular joints cause much waste. Waupaca granite is
well-suited for interior or exterior use in monuments or buildings. On
account of its brilliant coloring it is particularly adapted for ornamental
work, such as wainscoting and balustrades.

Waushara County. — A granite deposit at Lohrville and Redgranite in
southeastern Waushara County presents favorable quarry conditions.
Major joints strike N.30°-40°W. and N.75°-80°E. and are spaced at
sufficient width to give large sound blocks. Sheeting planes 2 to 4 feet
apart near the surface provide bench floors. A decided rift strikes
N.50°E. Several coarse granite dikes traverse the deposit, and pegma-
tites, veins, and knots are present in some quarries, though in others they
are absent. About 90 per cent of the rock consists of feldspar and
quartz, with subordinate hornblende and muscovite. It is light pink
(considerably lighter than the Montello granite), is of uniform, fine-
grained texture, and takes a good polish. Three or four companies
produce monuments, paving blocks, curbing, rubble, and rough construc-
tion stone.

New Hampshire. — In 1928 the block granite produced in New
Hampshire was valued at $1,359,229, or 5.5 per cent of the value of total
production in the United States. Distribution among the various uses in
1928 on the basis of value was as follows: Building, about 50 per cent;
monumental, 19; curbing, 19; paving, 11; and rubble, 1. During recent
years building stone has shown an upward trend in production, while
that used for monuments has declined. Production in 1929 was valued
at $1,063,112; in 1930, $1,411,084; in 1936, $293,540; and in 1937,
$359,451. Granite production is confined chiefly to Carrol County in
the east-central part of the State and to Cheshire, Hillsborough, and
Merrimack Counties in the south. Gray, bluish gray, and various pinks
are the prevailing colors.

Carroll County. — Building and memorial granites are produced near
Redstone and Conway. There are two principal varieties — a coarse-
grained, light pinkish gray biotite granite, "Conway Pink," and a coarse-
grained, dark yellowish green biotite-hornblende granite, "Redstone
Green." Though in contact, they represent originally different materials.
Sheeting planes in the pink granite are 4 to 30 feet apart and arch across
the axis of the hill. The most abundant joints strike east and west and
are 5 to 40 feet apart. The rift is horizontal and the grain vertical in an
east-west direction ; they appear to follow sheets of microscopic cavities in
the quartz grains. Pegmatites and black knots appear in places. In the
green-granite quarry sheets are 11 inches to 14 feet thick and dip about

GRANITE 135

15°W. Joints, rift, and grain are the same as in the pink rock. Both
varieties are used in buildings, as well as for polished columns and
memorials.

Cheshire County. — A fine-grained, light bluish gray biotite-muscovite
granite occurs near Fitzwilliam and Marlboro, adjacent to the southern
border of the State. Estimated mineral percentages are: Quartz, about
44; feldspar, 46; and mica, 10. The granite takes a good polish and is
well-adapted for fine carving. The rift is horizontal and the grain vertical,
striking nearly east-west. In places pegmatite dikes and black knots
are present. Near Marlboro the sheets are 6 inches to 6 feet thick, and
joints are more plentiful than in the rock near Fitzwilliam, where neither
sheets nor joints are well-developed. Stone from the latter district, sold
under the trade names "Victoria White" and "Snowflake," is used for
buildings and monuments. Paving stones are the principal products of
the Marlboro quarries.

Hillsborough County. — Milford, where 10 or 12 companies are in
operation, is the most important granite center of New Hampshire.
"Milford Granite" is generally a fine, even-grained, gray rock of light
and dark shades, some having a slight bluish, pinkish, or buff tinge.
Although variable the major joints fall in a general way within two main
quadrants, N.15°-50°E. and N.35°-80°W. In some quarries they are
spaced only 3 to 5 feet apart but usually exceed 10 feet. The rift is
generally horizontal and grain vertical, striking N.70°-80°W. In places
trap dikes have altered the color of the granite. The stone takes a
good polish, with marked contrast between cut and polished surfaces;
it is also well-adapted for carving. Building stone, monuments, paving
blocks, and curbing are manufactured. A fine-grained, buff-gray monu-
mental granite closely related to the Milford rock is obtained near
Brookline and South Brookline, that from the latter locality being
marketed as "Brookline Blue."

Merrimack County. — An important deposit of fine-grained, medium
gray muscovite-biotite granite occurs on Rattlesnake Hill near Concord.
"Concord Granite" is used for cut building stone, monuments, paving,
curbing, and ashlar. In one large opening typical of the district sheets
are only 6 inches thick in the upper 30 feet but increase to a thickness of
40 feet at a depth of 130 feet. The joints, which strike N.62°E. and
N.45°W., are few. The rift is horizontal and grain vertical, striking east-
west. A few pegmatite dikes and quartz veins occur. Concord granite
was used in construction of the massive edifice of the First Church of
Christ, Scientist, in Boston, Mass. At Suncook, south of Concord, an
even-grained, light gray granite, marketed as "Allenstown Granite,"
is used for building purposes, paving blocks, and curbing. It has been
employed in many large buildings.

136 THE STONE INDUSTRIES

Minor Producing States

In preceding pages granites of the eight principal producing States
have been described. Consideration will now be given to a group of eight
States of less importance in this industry. Like the major producers,
they will be considered in the order of their production in 1928.

New York. — The value of block granite sold in New York in 1928 was
$948,991, which was 3.8 per cent of the total value of production for the
United States. About 82 per cent was used for building purposes and
18 per cent for monuments. Since 1923 the building-granite industry of
the State has grown rapidly, annual production value increasing from
less than $50,000 to nearly $800,000. This increase is due partly to the
demand for stone in the construction of the Cathedral of St. John the
Divine in the city of New York; however the demand for building granite
has decreased since 1928. Total production in 1929 was valued at only
$301,486; in 1930, $497,576; in 1931, $430,042; and in 1932, $78,661.

Production in New York is restricted to two areas, the Adirondack
region in the north and the Highlands in the southeast.

Adirondack Granites. — The most important northern granite occurs
near Ausable Forks, Clinton County. Anorthosites (granitoid rocks, the
essential mineral of which is plagioclase), syenites, and true granites occur
in this district. Although the anorthosites and granites are very attrac-
tive, recent development has been confined chiefly to the green syenites.
The typical syenite consists of about 75 per cent feldspars and 25 per
cent other minerals, including pyroxene, magnetite, and zircon. It is
medium-grained, is dark to yellowish green, takes a good polish, is
attractive for monumental purposes, and is also used to some extent for
building.

Attractive red granite is quarried on Wellesley and near-by islands in
the Thousand Island district, Jefferson County. It is suitable for
monuments and building purposes, but production has recently been
confined to paving blocks only. A gray to pinkish type occurring near
Alexandria Bay is also used in this way.

Granites of Southeastern New York. — The granite industry of West-
chester County is becoming increasingly important. Stones of two
types, light pinkish gray and a rich yellowish brown, are obtained from
the Mohegan quarry about 3 miles east of Peekskill. The yellowish
brown, one of the most attractive eastern granites for structural and
monumental work, is widely used in New York City. Joint systems and
other quarry conditions are favorable. Granite quarried about 1 mile to
the south in the Millstone Hill district is gray to almost white and
suitable for both building and monumental uses. At West Point,
Orange County, dark-gray gneiss has been quarried for construction of
the Military Academy buildings.

GRANITE 137

Near Yonkers a light blue to reddish granite with gneissoid foliation
is obtained for rough construction work. Similar banded granites for
rough building are quarried at various points near New Rochelle. Rock
for building and monumental use occurs near the Bronx. Much of the
granite in this area north of New York is useful as rock-faced ashlar for
residential building.

California. — Production of block granite in California was valued at
$620,790 in 1928. About one fourth was monumental and three fourths
building stone. The value of building granite has fluctuated greatly.
In 1925 it reached a high point of $1,200,000 but declined to less than one
sixth of that amount in 1928. A large proportion is used in San Francisco
and Los Angeles, therefore the demand depends to quite an extent on
local conditions. Paving, curbing, and rubble production was very
small in 1928 but increased greatly in 1929 and 1930. Total production
in 1929 was valued at $1,560,314; in 1930, $1,047,256; in 1936, $247,967;
and in 1937, $78,412.

During recent years granites for building and monumental uses have
been produced in Fresno, Imperial, Madera, Nevada, Placer, Plumas,
Riverside, Sacramento, San Diego, and Tulare Counties. A high-
quality, medium-grained building and monumental granite, light gray
specked with brilliant black mica crystals, is produced at Raymond,
Madera County. It has been used widely in San Francisco for residences,
hotels, banks, and State and Federal buildings and also quite extensively
for monuments and mausoleums. The granite near Rocklin, Placer
County, is light gray and of fine- to medium-grained texture ; it is used for
buildings and monuments, chiefly the latter. At Porterville, Tulare
County, near Perris, Riverside County, and also in Fresno and Plumas
Counties fine-textured, dark blue hornblende diorites classed as black
granites are quarried for monumental uses.

Near Lakeside, San Diego County, a fine-grained, light gray granite
known as "Silver Gray" is quarried for monumental and other orna-
mental work. Granite is also produced in this county at El Cajon,
Escondido, Santee, and near Temecula, the latter locality providing a
dark blue rock. Building and monumental granites are obtained at
Corona, Riverside, and Wineville, Riverside County, and near Academy,
Fresno County. Granite for levees and reclamation work is quarried at
times near Andrade, Imperial County. Monumental stone is quarried
at Nevada City, Nevada County, and near Chilcoot, Plumas County,
that from the latter place being sold as "Light Pearl." A quarry at
Folsom, Sacramento County, provides stone for the construction of
prison buildings.

Maryland. — Block granite produced in Maryland in 1928 was valued
at $430,946, or 1.7 per cent of the total production value for the United
States. About 87 per cent in value was used for structural purposes,

138 THE STONE INDUSTRIES

chiefly as rough building stone, about 10 per cent as rubble, and the
remainder as curbing and paving stones. The building-granite industry-
has grown from a value qf less than $50,000 in 1919 to nearly $400,000
in 1928. Production in 1929 was valued at $229,080; in 1936, $44,955;
and in 1937, $190,546.

The Maryland granites are confined to a belt running north-east from
the Potomac River to the Pennsylvania border, the southern end of the
belt extending from Washington, D. C, to a point near Seneca. It
occupies a position on the eastern slope of the Piedmont Plateau bounded
on the east by the gravels and clays of the Coastal Plain and on the west
by the less crystalline rocks of the western Piedmont slopes. Within
this zone granite is prominently developed in about 15 areas, and in at
least 5, quarries of considerable importance have been developed. The
more important commercial deposits are the granites of Cecil and
Baltimore Counties and the granite gneisses of Baltimore and Mont-
gomery Counties.

Granites of Cecil and Baltimore Counties. — At Port Deposit, Cecil
County, about 3 miles above Havre de Grace on the Susquehanna River,
a light bluish gray biotite granite occurs. A noticeable feature of the
rock is a secondary gneissic structure which is due to parallel arrangement
of the mica flakes. It is uniform in texture and color, and quarry condi-
tions are favorable. Moderately spaced joints are in three systems, two
at about right angles to each other, while the third intersects the major
series at about 60°. Quarrying is facilitated by sheeting planes. The
granite is used principally for building purposes, such use dating back to
1816 and 1817 when large stones were supplied for abutments of a bridge
across the Susquehanna River.

An attractive gray biotite granite, widely used for general building
purposes and to some extent for memorial stone, occurs northeast of
Woodstock over the county line in Baltimore County. Well-defined
sheeting planes dip 10 to 15°, but jointing is somewhat irregular.

Gneisses of Baltimore and Montgomery Counties. — A dark to blue-gray
biotite gneiss occurs near Baltimore. Conditions favor quarrying, as
sheets dipping 30 to 40° are 4 inches to 5 or 6 feet thick, joints are in two
series approximately at right angles and moderately spaced, while the
grain (rift) is vertical and nearly parallels one of the jointing systems.
The rock breaks out so readily into cubical blocks that scarcely any
explosives are necessary. It is used chiefly for rough construction in and
about Baltimore.

In southern Montgomery County a similar dark gray granite gneiss is
used for bridge, house, chimney, and foundation building. It is so well-
supplied with joints and sheeting planes that it is easily quarried. Iron
oxide stains in the joints provide attractive nonfading colors for "seam-
faced granite." Several bridges on the new Mount Vernon Highway and

GRANITE 139

many other artistic structures including numerous residences in and near
Washington, D, C, are built of stone from these quarries.

Rhode Island. — Granite in the form of dimension stone produced in
Rhode Island in 1928 was valued at $413,707, or 1.7 per cent of the value
of total production for the United States. Monumental stone dominates
the industry, amounting to 92 per cent in value of the total for 1928.
About 4.4 per cent was used for building and 3.6 per cent for curbing.
Production of building granite was much greater during pre-war years
than now. Production in 1929 was valued at $348,173 ; in 1930, $366,602;
in 1936, $292,577; and in 1937, $320,712.

The industry is centered in and near Westerly and Bradford, Washing-
ton County. The deposits are unusual, in that they take the form of
massive dikes 50 to 150 feet thick intruded into the older granite gneisses,
which dip 30 to 45° to the south. The chief j oint systems run N. 10°-25°E.,
though various other systems have been noted. The rift is horizontal or
slightly inclined, and the grain is vertical or nearly so. Three main types
of commercial granite occur: "Westerly Pink," sometimes called
"Westerly Statuary," a pinkish or buff biotite granite (quartz monzonite)
of very fine uniform texture; "Blue Westerly," a bluish gray biotite
granite of fine, even-grained texture; and "Red Westerly," a reddish gray
granite speckled with black, having an even-grained medium, inclining to
coarse, texture. "Westerly Pink" and "Blue Westerly," the fine-
grained rocks, are used for monuments, and the coarser-grained red rocks
for construction. The pink and blue varieties take a high polish and are
attractive in color and texture. They are well-known to the monument
trade and have been widely used for many years.

Connecticut. — The value of block granite produced in Connecticut in
1928 was $396,344, or 1.6 per cent of the value of production for the
entire country. About 61 per cent was devoted to monumental purposes,
23 to building, and 16 to curbing. Production in 1929 was valued at
$710,739; in 1930, $496,124; in 1936, $144,108; and in 1937, $233,059.

Granites, granite gneisses, and related rocks occur in many parts
of the State, and their geologic relations are complex. Production of
dimension stone is confined chiefly to four counties — Hartford, New
Haven, New London, and Windham.

Hartford County. — Near Glastonbury a biotite granite gneiss occurs
in nearly horizontal sheets up to 3 feet thick. The rift follows the folia-
tion, dipping about 10° in a direction N.50°W. The rock is well-adapted
for rough construction and curbing, and the products are sold chiefly
in Hartford.

New Haven County. — Near Ansonia a blue-gray muscovite-biotite
granite gneiss is quarried for rough construction and curbing. The most
important quarries of the county are near Branford and Stony Creek.
The "Branford Red" rock is a reddish gray biotite granite gneiss of

140 THE STONE INDUSTRIES

medium to coarse, irregular texture. It is an attractive building stone
and has been used widely in many important structures; it is also
employed to a limited extent for monuments and curbing. "Branford
Pink" is another type produced in this district. "Stony Creek Red" is a
reddish gray coarse-grained gneissoid granite used for buildings, monu-
ments, and mausoleums.

New London County. — The most important granite quarries of Con-
necticut are in southern New London County near East Lyme, Groton,
Millstone, Niantic, and Waterford. At East Lyme and Niantic an even-
grained, pinkish gray granite provides an attractive monumental stone
sold under the name "Golden-Pink Niantic." Like the Westerly (R. L)
granite it occurs as a dike, in this instance about 40 feet thick intruded
into a gneiss. At Groton a fine-grained, greenish gray granite is quarried
for monuments. Production is most active in the Millstone and Water-
ford districts. "Millstone" granite which is available to both rail and
water transportation is a fine-grained, dark gray stone used for monu-
ments, paving stones, curbing, and to a limited extent building stone.
At Waterford the rock is buff-gray, but the hammered face is light gray.
It takes a fine polish and is marketed as "Connecticut White," being used
as an architectural stone, for monuments, and for paving stones. Like
the other granites of this district it occurs in dikelike masses.

Windham County.— A biotite granite gneiss is quarried near Oneco in
southern Windham County near the Rhode Island line. "Oneco" is an
attractive fine-grained, dark bluish gray stone used for building purposes
and for curbing.

Pennsylvania. — Granite dimension-stone production in Pennsylvania
in 1929 was valued at about $383,500. About 70 per cent of this amount
was building stone; 22, monumental; 6, rubble; and 2, paving stones.
The 1928 figures were not representative. Production in 1930 was valued
at $359,045; in 1936, $263,287; and in 1937, $268,859. Pennsylvania is
unique in that large quantities of granite gneiss are quarried for house
construction and other local uses, particularly in the Philadelphia district.
Figures as reported are probably low because a great number of small
operators do not submit reports.

Monumental Granites. — Diabase and gabbro, classed as "black
granites" are produced in small quantities in Berks County, and in larger
quantities in Bucks and Chester Counties. Black granite has been
quarried in Bucks County near California — "French Creek Black" at
Roedey and "Blue and Dark Pearl" at Shelly — but recent production
has been chiefly from the Coopersburg district. A jet-black stone show-
ing splendid contrast between polished and tooled surfaces is marketed as
"Bonnie Brook Black Granite." Similar stone is produced near Saint
Peters, Chester County.

GRANITE 141

Building Granites. — Practically all the rock classed as building granite
is an attractive, durable, dark granite gneiss which occurs abundantly in
many parts of Philadelphia and Delaware Counties and to some extent in
Montgomery, Chester, and Bucks Counties. None of the quarries are
large, though some provide considerable tonnage for use in and about
Philadelphia. In many places stone excavated in digging cellars is used
for foundation work and even for buildings. The extensive use of these
gneissic rocks has had a marked influence on the architecture of the
Philadelphia district. Some of the buildings have withstood weathering
influences remarkably well for more than 140 years.

South Dakota. — The value of block granite produced in South Dakota
in 1928 was S220,898, or 0.9 per cent of the value of total production for
the United States. Practically the entire amount is classed as monu-
mental stone. Before 1925 South Dakota was a producer of granite in a
very small way, but since that date the industry has grown rapidly.
Production in 1929 was valued at $280,245; in 1930, $397,047; in 1936,
$406,115; and in 1937, $547,334.

Production is confined almost exclusively to Grant County, where
about five companies operate. The deposits are part of the granite belt
of the upper Minnesota River Valley, which is described in the section
on Minnesota, and the rock quarried near Milbank and Bigstone City is
similar to that near Ortonville and Odessa, Minn. It is sold under the
trade names "Hunter's Mahogany" and "South Dakota Mahogany."
Some of the stone is shipped in rough blocks to finishing plants in Orton-
ville, Minn.

Rushmore Mountain, in the Black Hills of South Dakota, has been a
center of interest since 1929, when Congress authorized funds for carving
a gigantic memorial on the granite mountain face. A brief story of Our
Country written in part though not completed by Calvin Coolidge will
be carved deeply upon an entablature 80 feet wide and 120 feet high;
accompanying this history, carved in colossal proportions, will appear
the figures of Washington, Jefferson, Lincoln, and Theodore Roosevelt.
A related project at Stone Mountain, Ga. is described under the granites
of Georgia.

Texas. — Block-granite production in Texas in 1928 was valued at
$191,084, or 0.8 per cent of the value of total production for the United
States. Production in 1929 was valued at $165,807 ; in 1930, $220, 189 ; in
1936, $66,708; and in 1937, $52,361. The industry is confined chiefly
to Llano, Burnet, and Gillespie Counties in the west-central part of the
State. Llano, the most productive county, is the source of a fine- to
medium-grained, light to dark gray granite which is used almost entirely
for monuments. A coarse-grained red granite quarried at Granite Moun-
tain near Marble Falls, Burnet County, is well-adapted for building

142 THE STONE INDUSTRIES

purposes and was used for the construction of the Texas State Capitol at
Austin. It is also used for jetties, breakwaters, and other wave-resistant
structures and employed to a limited extent for monuments. Near
Fredericksburg, Gillespie County, an attractive red monumental stone is
quarried. Most of the products are sold within the State, though some
are shipped as far as New York City.

Other Producing States. — The 16 States discussed in the preceding
pages provide nearly 96 per cent of the production of granite as dimension
stone in the United States. Most of the remaining 4 per cent is reported
from six States — South Carolina, Colorado, Oklahoma, Delaware,
Montana, and Washington. In production value some of these States
exceed members of the minor group of eight States previously described,
but the number of producers is so small that production statistics have
been withheld to avoid revealing individual figures.

An attractive fine-grained, gray biotite granite quarried at Rion,
Fairfield County, S. C, is sold widely for monuments under the trade name
"Winnsboro Blue."

Colorado also produces attractive monumental granites valued at
more than $200,000 a year. Chief production is from Salida, Chaffee
County, where a fine-grained, dark blue-gray quartz diorite is sold under
the names "Salida Blue" and "Salida Dark Gray." Monumental stone
is also obtained in Fremont County.

Oklahoma and Montana are producers of monumental granite, and
Delaware supplies a rough construction stone similar to that produced in
eastern Pennsylvania.

An attractive dark red granite or syenite is quarried near Graniteville,
Iron County, Mo. The products are monumental stone and paving
blocks, the former being marketed widely as "Missouri Red "

A light gray granite has been quarried quite extensively in Little
Cottonwood Canyon about 20 miles from Salt Lake City, Utah, and used
for building purposes in that city.

Block-granite production in the State of Washington ranges from
$10,000 to $50,000 a year in value. The most important production
center is Medical Lake, Spokane County, where a fine- to medium-grained,
light gray granite is quarried, chiefly for the manufacture of memorial
stones. A small production of building and monumental granite is
reported at times from Index, Snohomish County.

Volcanic tuffs and related rocks are used to some extent for building
in Idaho, Arizona, New Mexico, Nevada, and California. Those in
Idaho have been described by Behre.^'^ The Arizona State Capitol and
several buildings of the University of Arizona are built of tuff. An

2^ Behre, C. H., Jr., Tertiary Volcanic Tuffs and Sandstones Used as Building
Stones in the Upper Salmon River Valley, Idaho. Contributions to Economic
Geology, pt. 1, 1929, U. S. Geol. Survey Bull. 811-E, pp. 237-248.

GRANITE 143

ash-gray tuff weighing only 65 pounds a cubic foot occurs near Pioche,
Nev. Nails may be driven into it almost as easily as into wood. Porous
tuff and pumice are cut into blocks and used as natural light-weight
building materials.

QUARRY METHODS AND EQUIPMENT

Choice of Location.— Granites occur widely in many States. Single
masses, as indicated by numerous related outcrops, may extend over
thousands of square miles. However, relatively few of these occurrences
have the qualities, locations, or working conditions requisite for adapt-
ability to industrial uses. Nature has been the fabricator of the rocks,
and man is powerless to change the inherent qualities of native beds;
therefore, selection of an area of rock with qualities suitable for industrial
uses is of paramount importance. First, outcrops should be examined
carefully. If a mantle of overburden hides the surface of the rock it may
be trenched, but adequate study can be made only when it is removed.
Stripping may be done by any method described in a previous chapter.
Some quarrymen recommend examination of rock during or immediately
after a rain, because hair lines, streaks, and knots ai^e recognized more
easily on a wet than on a dry surface. Areas chosen for quarrying
usually include masses of rock of uniform texture, attractive color, and
relative freedom from irregular or closely spaced seams and from dikes,
knots, or hair lines. Requirements for monumental and polished archi-
tectural stones, are most rigid; but more liberal variations in color and
texture are permissible for building, paving, and curbing granite, while
rock of quite uneven texture and color, such as the gneisses and schists,
may be used for rubble and other rough-faced types of building stone.

Plan of Quarrying. — The position and direction of quarry walls
usually are governed by the joint systems, because an open joint usually
constitutes a "heading" or quarry wall. Quarrying conditions are most
favorable where two systems of vertical joint seams are at right angles to
each other, as this permits easy development of a rectangular quarry
opening and the production of rectangular blocks. Many granite
deposits occur as domes rising above the general level, permitting wide and
shallow quarries, with easy access. This type of quarry has many
advantages, particularly in New England because the sheeting planes,
which assist greatly in separation of blocks, are almost invariably much
closer together near the surface than at depth. A typical bench or shelf
quarry is shown in figure 23. In some places quarries are sunk to depths
of 200 feet or more. Deep quarrying may be occasioned by restricted
property lines or by improvement in the quality of the rock at depth.
The plan of quarrying may be influenced by dikes or other structures.

Quarry Operations. Drilling. — Drilling greatly exceeds every other
quarry operation in importance, for granite is so hard that no tools but

144

THE STONE INDUSTRIES

drills can cut it in a quarry. Hand-sledged drills date back many years
but have been gradually superseded by steam-driven reciprocating drills.
The latter types, both steam- and air-driven, are still in use, but com-
pressed-air hammer drills are most common in modern granite quarries.
Drilling equipment has been improved greatly during recent years. The
increasing rate of drilling is due in part to the use of better machines and
in some measure to the employment of highly efficient mechanical drill
sharpeners. A modern quarry blacksmith shop is a marvel of speed and
accuracy in reconditioning drill bits.

The principal constituents of granite are, with the exception of mica,
as hard as, or harder than, steel, hence drill bits dull rapidly and lose their

Fig. 23.

-A typical bench or shelf granite quarry in Vermont with convenient railroad
transportation.

gage as a result of abrasion of the outer edges. Therefore, after depths
of 2 to 4 feet are attained steel is changed, and with each change a bit
M to }{q inch smaller is used. In general practice, many holes are
drilled 12 to 15 feet deep, and depths of 20 to 30 feet are not uncommon.
Starting bits are l^i to 2^i inches in diameter on the cutting end; the
larger size is used for deep drilling.

A great advance in drilling practice was attained with the invention
of hollow steel. Exhaust air passes down the hole in the center of the
bit and blows rock dust from the cutting edges, promoting effective work.
Air-operated devices for feeding the bit downward and for lifting the drill
head when steel is changed have reduced greatly the physical labor and
increased the speed of drilling.

GRANITE 145

The drilling rate in granite is slower than in most rocks. At Westerly,
R. I., thirty 4-foot holes a day is a fair average rate attained with a
tripod reciprocating drill using a 1^^- to 2-inch bit. At Barre, Vt. each
bar-drill machine averages 100 to 120 linear feet a day for moderately
deep drilling, using a 2,^:4-inch bit as a starter. Exceptional rates of
175 to 200 feet a day have been attained.

A bar drill is a type of equipment which has long been used but
recently has been greatly improved. A horizontal bar 12 to 14 feet long
is supported by a pair of steel legs at each end. A heavy hammer drill is
mounted on the bar and may be moved quickly to any desired position by
means of a pinion working in a rack of cogs extending the full length of
the bar. The chief function of this drill is to make rows of closely spaced
holes exactly in line and in one plane. A four-point hollow steel bit
generally is used. Reciprocating drills mounted on tripods are sometimes
used for deep drilling, and are occasionally used on bars.

For shallower holes used in plug-and-feather wedging hammer drills
held in the hands usually are employed. The ordinary hammer drill,
with a six-point bit and automatic rotating device, is used for "foot
holes," a name applied in Vermont to holes 1 or 2 feet deep. Hand-held
hammer drills are also used for putting down deep single holes or small
groups of holes for blasting. These are much lighter in weight than
the machines used on bars, and the drilling rate is somewhat slower,
averaging 75 to 100 feet a day.

For holes 4 to 6 inches deep and about ^^ inch in diameter a smaller
type, known as a "plug drill," is used. Valve action depends upon
pressure of the bit, therefore it operates only when the steel is pressed
firmly against the rock. The bit, usually of the chisel-point type, is
rotated by a hand wrench or automatically as a result of special
sharpening.

Reaming. — A reamer is a flanged tool driven into a drill hole to cut
grooves on opposite sides. Reaming greatly assists blasting, especially
by the Knox method, mentioned in its application to granite quarrying
under Blasting. It may also be employed to assist straight splitting
when the wedging method is followed.

Broaching. — Broaching is the process of cutting out webs or "cores,"
as they are sometimes called, between closely spaced drill holes to make a
continuous channel. A broaching tool resembles a flattened drill bar.
The cutting end is about 3 or 3)^^ inches wide and \}i inches thick,
sometimes with transverse ridges on the face. It may be used in a drill
head. After a row of holes has been completed the full length of the bar
broaching tools are substituted for drills, and all cores or webs between
holes are cut away. Broaching is usually slow and with increasing depth
becomes even more laborious, for as drill holes become smaller the cores
or webs become correspondingly wider.

146 THE STONE INDUSTRIES

Blasting. — Blasting is commonly employed to obtain large fractures,
but great care must be exercised in the use of explosives to avoid shatter-
ing the rock. Dynamite is used for breaking up waste rock, but in good
granite the slower-acting black blasting powder is invariably employed.
A charge is the minimum amount that will make a single fracture. If too
much explosive is used incipient fractures may be developed in quarry
blocks. Such fractures, which may be so small as to be unobservable
until the rock is polished, are doubly detrimental, as they not only cause
waste but result in condemnation of a block after much time and labor
have been spent in shaping and finishing it.

Straight, even breaks, with a minimum number of drill holes, may be
made by employing the Knox system. This involves the use of a reamer
which when driven into the hole cuts grooves about one-fourth inch deep
on opposite sides. Care is taken to cut the grooves exactly in line with
the desired direction of splitting. This system, already described in
detail in the chapter on sandstone, also involves the use of an air space
above the powder charge, which increases the effectiveness of the explo-
sive force. A uniform, straight fracture with an area greater than
100 square feet sometimes is made by blasting in a single reamed drill
hole. Occasionally several parallel holes are made, or three or four may
be drilled in a fanlike arrangement.

Wedging. — Channeling and blasting have their proper places in quarry
work; but most fractures, especially those of smaller area, are made by
wedging. Plug-and-feather wedging has been described. Small plugs
and feathers are used in ^^-inch "plug" holes 4 or 5 inches deep and

6 to 18 inches apart. They are sledged lightly in turn back and forth
along the line until a fracture is made. Plug-hole wedging is effective
in rift and grain directions, even for large breaks. A few years ago the
writer observed in a Georgia quarry a single mass of granite 8 feet thick,

7 feet 8 inches wide, and 375 feet long separated by the plug-and-feather
method with holes 5 inches apart and only 5 inches deep. If a break is to
parallel the hard way of the rock "foot holes" 1 to 1}^ feet deep are
drilled 1}^ to 4 feet apart, with plug holes between them. The longer
plugs and feathers used in the deeper holes are known as "foot wedges."
The straightest fractures are obtained when made in the center of a rock
mass. If a small piece is to be wedged from the side of a larger block the
fracture tends to run toward the lighter side. In making large fractures
the wedging process is not hurried. Plugs are driven firmly, and then
a little time is allowed for the fracture to start before sledging is resumed.

Hoisting. — Most granite quarries are equipped with derricks having
steam or electric hoists. In wide quarries where booms can not reach all
parts, stone blocks or boxes of waste may be handled beyond the boom
radius by attaching a line from some other near-by derrick, the two work-
ing in conjunction.

GRANITE 147

In New England wooden derricks with masts and booms of Oregon
pine are generally used. They are large and powerful, can handle
blocks weighing 40 or 50 tons, and in exceptional instances attain a
capacity of 80 tons. At some Maine quarries the original timber for the
boom is sawed lengthwise in the center, blocks of timber are placed
between the two parts at various points, and the halves are bolted
together through the blocks. Sheaves are mounted in the space between
the halves. Such "split" booms are less liable to warp and twist than
single timbers, and therefore the sheaves run true and do not wear the
cable. A 50-ton-capacity derrick may have a mast 100 feet high and a
boom 95 feet long. In Minnesota angle-steel derricks generally have
replaced wooden derricks. Several quarries are equipped with overhead
cableways, but their lifting capacity is usually very much lower than that
of derricks.

Quarry Methods. Influence of Physical Properties and Rock Struc-
tures.— Channeling-machine methods used in the softer rocks (limestones,
sandstones, slates, and marbles) do not apply to granite, which is an
exceptionally hard rock; hence, as previously explained, drilling is sub-
stituted therefor. As artificial cuts are costly, full advantage is taken of
open seams or "headers" for quarry or bench walls. As far as possible,
all block separations parallel the directions of easiest splitting — the rift
and grain. It is a fortunate circumstance that in many granite districts
the rift parallels one of the major jointing systems, for in the natural
development of a quarry, successive partings thus parallel both rift and
joints.

Sheeting planes or "bottom joints" greatly assist quarrying. In
fact, vertical breaks can not be made successfully until the mass is free at
the quarry floor. If open sheeting planes are provided in nature, succes-
sive masses may be removed with ease. If such bottom joints are far
apart or absent artificial sheeting planes must be made, possibly by
drilling a series of horizontal holes, sometimes termed "lift holes," and
making a fracture with wedges or by the use of explosives. The cost of
quarrying is usually relatively high in deposits where floor breaks must be
forced by wedging or blasting.

Many deposits occur in characteristic domelike form, and sheeting
planes usually are arched to parallel in a general way the surface contour
of the rock. This attitude of sheeting planes is an advantage in quarry-
ing, for as an opening is made in the side of the dome the quarry floor
slopes away from the working face, providing automatic drainage and
greatly facilitating the movement of heavy blocks of stone. Sheets are
sometimes relatively thick, and joints are spaced close together. Open-
ings in deposits having such a preponderance of joints are sometimes
termed "block quarries," because they provide massive cubical blocks.
Quarries in the St. Cloud district, Minnesota, are of this type. Con-

148

THE STONE INDUSTRIES

trasted with them are the typical quarries of New England, where sheets
are thin and joints widely spaced. In such openings the quarry face
rises in a series of low steps. The layers are usually thin near the out-
crop, gradually thickening as the quarry face is worked back into the
dome. As a rule, they also gradually thicken with depth. Openings in
rock of this type are sometimes known as "sheet quarries." Figure 24
shows the typical New England sheet structure. Exceptionally, sheeting
planes are far apart in New England quarries, for example, in some at
Barre, Vt.

Channeling. — "Channeling" in granite quarrying has quite a different
meaning than when employed in limestone or sandstone. In the latter

Fig. 24

A typical New lingland granite (iu;ui\- illut^tI■alin

Me.

^lll'(•t ^Inicture; Stonington,

rocks it is the process of making a cut with a channeling machine, whereas
in granite it refers to the drilling of a closely spaced row of holes and
broaching or cutting out the narrow webs or cores between. Cuts thus
obtained are similar to those resulting from the operation of channeling
machines in the softer rocks. This method is employed in many quarries
in preference to blasting because, although slow and more costly, it gives
a straight surface and does not cause shattering. Its advantages are
most apparent in making cuts in the hard way. Channeled rock surfaces
are shown at the top and upper right corner of figure 25.

Primary Cuts. — The first step in quarrying is to separate the larger
masses from the solid ledge. To obtain space for movement of blocks
at the quarry wall it may be necessary to cut a channel. Wall channeling
usually is done in the direction of the head grain, or hard way. Channel-
ing tight ends is sometimes difficult because the rock in some deposits,

GRANITE

149

especially those in which few joints occur, is under compression, and when
the drill holes provide a means of relief the rock expands : thus pressure
may partly close the drill holes. It is claimed that at Stone Mountain,
Ga., a mass 60 feet long will expand 2 inches.

The most difficult step in opening up a new bench on a quarry floor is
to obtain a free face from which to work. To give necessary working
space a mass of rock 3 to 5 feet wide, and the depth of the bench, must be
removed. Different methods are employed to make such a trench or

Fig. 25.

-Granite quarry at Barre, Vt., in which various methods cf driUing are illustrated.
{Courtesy of E. L. Smith & Co.)

keyway. If the mass is flanked on either side by an open seam the inter-
vening rock may be removed by drilling and blasting. If open seams
can not be utilized holes may be drilled in two parallel rows 3 to 5 feet
apart, and the intervening rock shattered with dynamite may be removed
as waste. Another method is to make two channel cuts 10 to 15 feet
apart by the process described in a preceding paragraph and to remove
the mass of rock between them. This method is less wasteful than
blasting, as the rock between channel cuts may be removed as quarry
blocks and utilized, at least in part.

A unique method is employed in a large quarry at West Chelmsford,
Mass. A drum core drill, using steel shot as abrasive, cuts a series of
holes along the center and across the ends of the quarry. Webs 8 to 10
inches wide are left between the holes to protect the drill from rock

150 THE STONE INDUSTRIES

movement occasioned by pressure. The webs are removed later with
light powder blasts, and a channel is thus formed. The circular cores,
52 inches in diameter, are cleverly utilized by quartering them for the
manufacture of corner curbstones. They are more accurate in shape
and have smoother surfaces than rough-hewn curbstones.

Separation of Larger Masses. — When an open bench has been secured
by any of the methods previously described, free faces being thus pro-
vided, the next step is to separate large masses from the solid ledge. In
''block quarries" or "boulder quarries," as they are called in Vermont,
where sheeting planes are widely spaced, primary separations may set
free blocks weighing thousands of tons. If the bench approaches 20 or
more feet in height the larger fractures are made by blasting. "Lewis"
holes 2} 2 to 3 inches in diameter are drilled several feet apart and from
one half to almost the full depth of the bench, at the bottom of which is a
sheeting plane. A fracture is made by discharging black blasting powder
in the holes according to the method described under blasting. Usually
this break is on the rift or grain. In rock which splits easily three holes
in fan-like arrangement may suffice. A series of deep holes in which
explosives have been discharged are shown in the center of figure 25.

When a vertical break is thus made the mass of rock may still be
too heavy for wedging. If so, horizontal holes are drilled at a point about
halfway down the bench face, and light charges of powder are used to
fracture the rock along the plane of horizontal rift or grain. Some
quarrymen do not favor channeling beyond a depth of 10 or 12 feet. If
sheeting planes are 20 or more feet apart the rock is removed in two
''lifts," the bottom of the first being opened with powder charges in
horizontal holes.

In "sheet quarries" where sheeting planes are close together blasting
may be required only for making primary trenches, and all subsequent
breaks are made by wedging. In such deposits quarrying usually is
simpler and less costly than in those where sheeting planes are widely
spaced.

Forcing Sheeting Planes with Compressed Air. — An ingenious method
of making artificial bottom joints is employed in North Carolina and
Georgia. Certain deposits, notably at Lithonia, Ga., and Mount Airy,
N. C, consist of low, massive domes that are unique in that one may walk
over the bare surface of the rock for hundreds of feet without finding any
indication of a joint. Sheeting planes are likewise far apart or entirely
absent. To remove the larger masses of stone it is first necessary to
make artificial floor breaks.

At one Lithonia quarry as observed by the writer, two holes of about
3-inch diameter are drilled close together to a depth of about 8 feet.
Two men may work at these holes for weeks or even months. A very
small charge of black blasting powder, not more than a spoonful, is

GRANITE 151

placed in each and tamped with clay, and the charges are fired simul-
taneously with an electric battery. The force of the explosion starts a
small fracture running outward from the bottoms of the holes. This
process is repeated time after time, with gradual increase in the size of
charges, and the fracture extends slowly. A quarryman skilled in this
type of work can readily judge the extent of the fracture, for when
standing on the surface of the rock some distance from the drill holes he
can determine from the nature of the jar when charges are fired, whether
or not the fracture has reached the point over which he is standing.
Any attempt to hasten the operation by increasing the charges too
greatly would be disastrous, as it would force a vertical or inclined
fracture and render continuance of the process impossible. Solar heat
assists the process so materially that it is deemed advisable to suspend
operations in winter.

The blasting process is continued until the outward boundary of the
horizontal fracture forms a circle with a 60- to 80-foot radius. An iron
pipe is then placed in each drill hole and the space between the pipe
and the rock filled with jute or sand bags and melted sulphur, making
a strong, airtight joint. Connection is then made with the air line,
and compressed air at a pressure of about 100 pounds per square inch is
injected through the pipes to the fracture. The effect is remarkable, for
the air pressure immediately widens and extends the fracture until it
emerges at the surface on the flank of the dome or at some distant line on
the quarry floor. A sheeting plane thus formed may cover an area of
1 or 2 acres and provide a mass of rock large enough for an entire season's
operation. The above process is modified somewhat by different
operators.

Employment of compressed air to break rock in this manner does not
bear promise of being accepted as general quarry practice, because its
application is greatly restricted by quarry conditions. Most commercial
deposits are intersected by joint systems, and obviously open joints would
provide a means of escape for explosive gases generated during the
blasting process, rendering it ineffective and also permitting escape of the
compressed air used in the final operation. Thus, the process can be
employed only in those unique occurrences where joints are very far
apart.

Subdivision of Blocks. — After large masses are separated from a solid
ledge the next step is to subdivide them into blocks of the approximate
sizes and shapes desired for finished products or into sizes convenient for
removal from the quarry. Quarrymen follow the direction of rift and
grain in making secondary and following fractures, just as they do in
primary breaks. The wedging method is used almost universally.
Wedging in plug holes may suffice to give a straight fracture in directions
of rift and grain. For subdivision of large blocks the line of plugs may be

152

THE STONE INDUSTRIES

continued down the ends, as well as along the top, as shown in figure 26.
Wedging from both ends and top tends to insure a straight split. For
breaks on the hard way "foot holes" may be put down to depths of
12 to 18 inches and 2 or more feet apart, with several shallow plug holes
between. "Foot wedges" are driven in the foot holes, and small wedges
in the plug holes. Foot holes with four intervening plug holes are shown
at the left center of figure 25, page 149. Holes sometimes are reamed for
making splits on the head grain.

Fig. 26.-

-Subdivision of a block of granite in a Westerly, R. I., quarry by wedging on top
and end. {Photo by the author.)

The above methods apply where the weight is approximately balanced,
that is, where the line of drill holes is near the center of the mass. Fre-
quently there is a demand for a relatively thin mass of rock, possibly not
more than 2 or 3 feet thick but of wide area, such as for a platform or the
roof of a mausoleum. At Barre, Vt., separating such a mass is known as
"deep holing." Holes about 6 inches apart are drilled in line to almost
the full depth of the bench, and a fracture is made by driving "foot-hole"
wedges therein; or, sometimes long wedges are used. If shallow holes

GRANITE

153

were employed the fracture would curve and run out toward the thinner
mass, but deep ones carry the fracture straight through. The same rule
applies in the subdivision of smaller blocks. In figure 27 a thin slab that
has been separated by deep-hole wedging is shown suspended in midair.
It may be observed that the block was removed from a point near the

Aj^ \^'

Fig. 27. — A thin slab of granite that has been quarried by deep-hole wedging. {Courtesy

of E. L. Smith & Co.)

center of the photograph, where plug holes for the final vertical break
appear.

An interesting modification of the wedging method is used in Rhode
Island. For making a fracture 6 or 7 feet deep holes about 5 feet deep,
spaced 1 to 13>^^ feet apart, are drilled in a row. A steam pipe with numer-
ous right-angled tees is placed parallel with the row of holes, and lengths
of hose attached to the branch pipes are inserted to the bottoms of the

154 THE STONE INDUSTRIES

holes. Live steam is blown into the holes for 1 to 2 hours, and the expan-
sion caused by the hot steam makes the desired fracture.

Products of monumental granite quarries are of two main types,
which may be designated as stock sizes and specials. The former are the
standard sizes that satisfy the majority of manufacturers' demands
for smaller monuments supplied to the retail trade. As they may be kept
in stock quick delivery is assured. Specials are cut to order and may
be large or small. Most of them are used in larger, more expensive
monuments and mausoleums. They may be made up of 10, 12, or a
greater number of stones of different sizes and shapes, cut to size after an
order is received. The larger companies usually have a variety of blocks
on hand or have benches in the quarry available from which desired sizes
may be cut with little delay.

Removal of Stone from Quarry. — Several diverse methods are used for
removing granite blocks from a quarry. In wide, shallow quarries, like
those at Mount Airy, N. C, and Lithonia, Ga., standard-type tractors,
caterpillar tractors, auto trucks, or two-wheeled mule carts are employed.
For handling moderate-size blocks a caterpillar derrick crane may be
used. Derricks are usually employed for deeper, narrower quarries.
Derricks usually are placed in the most convenient positions for loading,
and for taking full advantage of a sloping quarry floor if such is
present.

As mentioned previously the tendency of sheeting planes or rift to
dip downward from the quarry face is of great advantage in removal of
blocks. At some quarries, notably at Stone Mountain, Ga., the quarry
floor is so steep that blocks slide to the lower edge, where they are lifted
by large derricks to standard flat cars for transportation to the mill.

Some New England water-front quarries are so convenient to docks
that derricks may place blocks directly on barges. Others have some
means of intermediate transportation, and supplementary loading der-
ricks are provided at the docks.

Service Yard. — The aim of the quarryman is to produce either
blocks of special sizes cut to order, or standard blocks that may be
marketed readily. In the course of quarrying many odd-size or irregular
blocks are produced ; others may contain imperfections in color or texture
in certain places only, necessitating the removal of defective parts. By
consulting his order sheet the yard foreman may find that certain special,
or smaller standard sizes can be obtained from irregular or defective
blocks with minimum waste, and some companies maintain what is known
as a "service yard" on the quarry bank where such blocks are subdivided
to best advantage.

Quarry Haulage. — Where quarries are on the water front direct
loading on barges is possible. Sometimes mills are so close to quarries
that little or no intermediate transportation is required, but generally

GRANITE 155

they are some distance from quarries. As granite usually is quarried in
large blocks standard railway cars and locomotives ordinarily are
employed for conveyance. Locomotive cranes are very convenient, as
they not only haul cars but load and unload blocks. This type of
conveyance is used at Westerly, R. I., and in other districts. Where the
distance from quarry to mill is short (as at Mount Airy, N. C.) overhead
cableways are used both for hoisting blocks from quarries and conveying
them to the mills. Wagon and truck haulage is used to a limited extent.

Disposal of Waste. — Waste at granite quarries results from many and
varied causes. Some of it is "sap rock," which consists of weathered or
stained material bordering open seams and extending into the rock from
a few inches to 2 or more feet. Irregular or closely spaced joints, as well
as dikes, streaks, knots, hair lines, or poor color, are common causes of
waste. Much rock is lost during manufacture. At Barre, Vt., waste
constitutes 80 to 85 per cent of gross production.

Disposal of waste is a difficult problem at many quarries. Some
operators have developed a market for part of it. At quite a number of
quarries waste is crushed and sold for road stone and concrete aggregate,
and large masses are sometimes sold for riprap. Other owners are using
the waste from the high-priced products to make cheaper materials, such
as ashlar and rubble, but success in such enterprises may be expected only
where there is a potential market within reasonable distance.

If a great volume of waste must remain unutilized it usually must be
hauled some distance, for if piled close to the excavation it may impede
future development. Various means of transportation are employed,
and alert quarrymen are constantly trying to simplify operation and thus
reduce costs. A common method of conveyance is by cable cars on
inclined tracks leading to the top of the waste heap, the tracks being
extended as the size of the pile increases. Many cars have automatic
trips that dump loads endways or sideways, and the expense of keeping,--
laborers continually at work on the waste heap is thereby avoided. In
many places overhead cableways, usually with self-dumping skips, have
been successful. Waste often is used to advantage in the neighborhood
of quarries and mills to improve harbors, to level low places, to build
roads, or to provide ballast for railways.

To most quarrymen elimination of waste is obviously of primary
importance; and much attention is being given to thorough understanding
of the splitting properties of stone, to efficient sawing and surfacing
equipment, and to the most complete utilization of the rock for a variety
of products.

Manufacture of Curbing. — The manufacture of curbing commonly is
conducted on the quarry floor or in an adjacent yard. Blocks usually
are split on the rift and grain to the desired thickness and depth, plugs
and feathers being used in small, shallow drill holes. Curb-stones are

156 THE STONE INDUSTRIES

of two types — straight and corner; the latter are, of course, curved.
Corner curb is the most expensive to make, as more stone is required than
for the straight and more labor needed for splitting and dressing. An
experienced worker can make a curved split. The part of the stone that
appears above the ground or pavement when a curb is placed in position
is dressed to a smooth surface, usually with a pneumatic tool, the rougher
projections first being removed with a hand tool and hammer; the part
that remains underground may have a much rougher surface. Specifica-
tions for size and surfacing differ in various cities.

Manufacture of Paving Blocks. — Paving blocks, like curbing, usually
are manufactured in or near the quarries. Blocks are subdivided by
driving plug-and-feather wedges in shallow drill holes, and the directions
of rift and grain are followed carefully because splitting is easier and stone
split in the directions of natural cleavage has smooth surfaces that require
little trimming.

A "bull wedge" is sometimes used for final subdivision. An air-
driven chisel-edged tool cuts a shallow notch parallel to the direction in
which the rock is to be split. Two iron "feathers" are placed in the
notch, and a short, blunt, steel plug is placed between them. One blow
on the plug or "bull wedge" with a sledge will split the block and provide
smooth, uniform surfaces. It is claimed that by such means a good
break can be made to parallel the hard way. The manufacture of paving
blocks is entirely a hand process that has changed little or none in the past
50 years. Stonecutters become very proficient in determining the
directions of rift and grain and in the use of tools.

Paving stones are made in a variety of sizes, and there have been
attempts to standardize and reduce the number of sizes. Market
quotations in New York usually specify 30 blocks a square yard. Specifi-
cations for granite paving blocks have been published by the American
Society for Testing Materials. ^^

Quarry Costs. — The cost of quarrying granite varies considerably,
depending upon quarry conditions, proportion of waste, and methods
employed. A detailed study by the United States Tariff Commission,
the results of which were published in 1929 (see bibliography at end of
chapter), reveals useful data relative to the monumental granite industry.
The average direct cost f.o.b. quarry for selected operations in Ver-
mont, Massachusetts, and Pennsylvania was found to be S2.07 a cubic
foot of unmanufactured stone.

MILLING METHODS AND EQUIPMENT

Some companies quarry only and sell rough blocks to finishing mills;
others own both quarries and mills; while a third group operates mills
only, buying rough blocks from quarry companies.

" A.S.T.M. Standards 1927, pt. 2, pp. 445-450.

GRANITE 157

Rough blocks of stone constitute the raw material handled in granite-
finishing plants. At first sight it might appear that rock, a commodity
so plentiful in nature, is quite ordinary and inexpensive, but the superior
quality demanded for monuments and ornamental building stone
requires such careful selection and preparation that costs are com-
]mratively high. First-class monumental granite in unfinished blocks is
worth $3.50 to $5 a cubic foot. The fabricator, therefore, must utilize
his material to best advantage, eliminate waste as much as possible, and
exercise skill and judgment in every operation, for mistakes are difficult,
if not impossible, to correct.

The granite-finishing plant of 30 or 40 years ago was a shed in which
blocks were dressed to desired sizes, shapes, and surface finish almost
entirely by hand. Machinery has gradually replaced many hand opera-
tions, and mechanization has increased with accelerating speed during
the past 10 years. Practically every large granite-cutting plant is now
equipped with pneumatic surfacing machines, saws. Carborundum
machines, lathes, and polishing machines. However, even in the best-
equipped mills, many operations must be classed as hand cutting.

Hand Cutting. General Processes. — Hand cutting includes the use of
hand tools and hammers, and also of pneumatic tools and surfacing
machines that are power-driven but guided over the surface by hand. A
rectangular block, as it comes from the quarry, is known as a "pattern."
It is raised and supported on timbers at a height convenient for working.
The cutter first studies the working drawing of the stone to be cut,
observes all dimensions, and measures the pattern to see that it will
make a block of the size and shape indicated on the diagram. He then
squares the upper surface and removes projections to an approximate
level, then the surface is smoothed, first with the coarser tools and then
with those that give a finer finish. When one surface is completed the
block is turned, and the other surfaces are smoothed in succession, each
being squared accurately with those already finished.

A variety of tools is used in cutting granite. Some are the property
of the cutters, while others are supplied by the company. They differ
in shape and in temper of the steel from those employed for the softer
limestones and marbles, though they may have the same names. Cutting
granite is in effect a crushing process, as the impact of a hammer on a tool
causes hard, brittle minerals to crumble into small fragments or dust.
The wooden mallets commonly used in driving tools for dressing softer
stones, are ineffective on granite, where sturdier implements are required.
The granite cutter's hand hammer is of steel weighing 2}4 to 4 pounds,
with faces hardened by tempering. The heads of cutting tools are
bluntly tapered and slightly rounded on the ends, which are also hardened
so that no burr results from continued hammering. Various hand and
pneumatic tools used in dressing granite are shown in figure 28. Each

158

THE STONE INDUSTRIES

tool has its special function and has been perfected by many years, even
centuries in some instances, of practical experience.

Granite cutting may not be so fine an art as metal machining or
cabinet making, but angles and dimensions must be reasonably true. In

HAND TOOLS

Peen Hammer

Point Chisel Chipper Hand Set or Tracer

Pitching Tool

Wedge and Shims

Scotia Hammer

Hand Plug Drill Bull Set Striking Hammer

PNEUMATIC TOOLS

Surfacing Machine Tools

Fig. 28. — Granite cutting tools. {Courtesy of Federal Board for Vocational Education.)

fine building and mausoleum work tolerances may not exceed one thirty-
second inch and rarely are restricted to one sixty-fourth inch.

Pneumatic tools are guided by hand, but the impact is supplied by
compressed air. The tool strikes very rapid blows which require no

GRANITE 159

effort by the workman; he therefore can direct his entire attention to
guiding it in the proper course. Much greater speed is attained by use of
such tools than hand hammers.

A "bull sett," one of the most useful tools employed in granite
dressing is a heavy, blunt-edged hammer held in position by one man
while struck with a sledge by another; it is used for removing irregular
ends, which may extend 6 inches or 1 foot beyond required dimensions
or for breaking sawed slabs transversely. The removal of unnecessary
rock by spalling is known locally as "pitching off." Skill in manipula-
tion, as well as keen understanding of the rift or grain of the rock, is
essential when using a bull sett, as a mistake in judgment resulting in a
spall breaking beyond the line ruins a block for its intended use.

Operation of Surfacing-machine. — While surfacing-machine work
may logically be classed with hand operations it is sufficiently distinct
to justify consideration in a separate section. It involves "roughing
down" surfaces to a comparatively uniform condition. The first step
in manufacture is termed "lining" and involves working the edges of a
block to required dimensions, usually with pneumatic chisels. The next
step, known as "pointing" or "surfacing," is to dress the faces to edge
dimensions with hand tools and hammers or, when surfaces are large
and rough, with a surfacing-machine.

The machine consists essentially of a cutting head mounted on a
horizontal swinging arm which can be raised or lowered to different
working levels. Cutting tools fit into the nose of the cutting head and
are driven against the stone by rapid blows of an air-driven piston ham-
mer. An operator guiding the tool over the surface of the stone repro-
duces the hand-pointing process on a larger scale and about five times
as fast. As the cutter travels over the rock it chips off fragments,
gradually working down to an even surface. A heavy tool removes the
larger projections, followed by various smaller types to finish the surface.
Common surfacing-machine tools are illustrated in figure 28.

A surfacer has numerous applications, such as smoothing rock before
polishing, smoothing curved or cylindrical surfaces, and recessing panels.
It may be employed for rough, heavy moldings and flutings. A four-
point tool, which has a square face consisting of four blunt projections,
generally is used for recessing and shaping, or for reducing surfaces to an
even plane before polishing. If a hammered-surface finish is desired
a bush hammer is used in the surfacing-machine. The latter consists
of a series of parallel steel plates, and the tools are graded 4, 8, 10, and
12, according to the number of plates, 12 giving the finest surface.
Building and mausoleum stone usually has a 10-cut surface, while a 12-cut
is preferred for monuments.

A screen of wire netting commonly protects workmen from flying
fragments of stone. As much dust is produced dust collectors usually
are provided.

160 THE STONE INDUSTRIES

Carving. — Carving is a hand operation that demands skill and experi-
ence. It is essentially the same process described in some detail under
limestone, though granite works much more slowly. A variety of
pneumatic tools is used. As a rule, fine-grained granites are best-adapted
for carving, though there are notable exceptions. Much of the intricate
carving and lettering formerly done entirely by hand is now accomplished
by sand blasting.

Sand Blasting. — Sand blasting marks an advance in the art of granite
carving comparable in importance to the advent of explosives or of
compressed-air drills in rock quarrying. It is more precise, capable
of greater detail, and much more rapid than any other carving
process.

A polished-rock surface is first coated with a molten rubberlike or
gluelike compound, known as "dope," which hardens to a tough, elastic
consistency. Lettering and other designs are imprinted on the surface,
and with a small sharp tool like a scalpel the coating is removed from all
parts that are to be cut below the surface. The cutting of symmetrical
designs, rose petals, ivy leaves, and trailing vines requires artistic talent
and infinite patience, but carving is accomplished much more expeditiously
in the rubbery compound than in solid rock.

Stone thus prepared is placed in an illuminated closed chamber in such
a position that the surface to be carved is vertical and faces the operator,
who observes it through a window. A nozzle, through which compressed
air at a pressure of 80 to 100 pounds per square inch drives a stream of
fine sand, or more commonly powdered Carborundum, is held through a
curtain which protects the operator from the abrasive dust. The sand
blast is directed against the design, and curiously enough the exposed
hard granite is quickly cut away while the sand has little or no effect
on the soft coating. Certain parts of letters or designs may be cut
}4 to 1 inch in depth. The precision and fineness of detail are remark-
able. Rose petals may be cut so thin that they are almost transparent.
In its higher refinements sand blasting may be done in successive steps.
Petals or leaves may be depressed to varying degrees, covered with a
protective coating, then outlined by deeper cuts. A screen background
produces a series of deep holes in lines resembling a honeycomb. The
delicate and exquisite detail attained would be impossible with hand
tools, and the time required is reduced to a mere fraction of that which
hand carving demands.

Mechanical Equipment. — Machines that have replaced the slow
laborious hand work employed 30 or 40 years ago cover three main
processes — sawing, smoothing, and polishing. Although much toil
has been eliminated in these important processes and production per
man has increased enormously since machines were introduced, improve-
ments constantly are being made.

GRANITE 161

Sawing. — In the early days of granite working drilling, blasting, and
wedging were the only known means of subdividing blocks. Granite is
difficult to saw, but many years of experiment have developed machines
that give effective service. Saws have been used occasionally for a
number of years but have been generally accepted only during the past
10 or 15. There are now two well-recognized methods of sawing granite
— with gang saws and with circular saws.

Gang saws similar in construction and operation to those described
in the chapters on sandstone and limestone are used most widely. The
frames of some saws travel back and forth in a straight line; others have
the swinging motion so common in limestone sawing. The blades are
one-half to five-eighths inch thick, with notches about a foot apart in the
lower edge to carry steel-shot abrasive beneath them. The rate of cutting
is 4 to 9 inches an hour. Most modern saw beds are equipped with
concrete sumps, in which used shot are collected and elevated mechan-
ically to a box above the saws for redistribution. Several blades may be
used, and as the frame holding them is carried downward by a worm
gear a block may be cut into slabs at one operation.

Circular saws for cutting granite are 5 to 12 feet in diameter and
provided with detachable notched-steel teeth. An abundance of water
is supplied, and steel shot are fed to the blade continuously. Some saws
are provided with automatic shot feed. Granite blocks are mounted
end to end on cars and the spaces between filled with plaster of paris
to keep the shot in the cut as the saw passes from one block to another.
Cars carrying blocks are conveyed slowly beneath the saw, and operation
is therefore continuous. Sawed slabs or blocks are removed and empty
cars lifted with an overhead crane, carried back to the starting point,
and placed on the track again. The rate of travel ranges from l^-i to as
high as 5 inches a minute; therefore the sawing rate in blocks 4 feet
thick is 25 to possibly 100 square feet an hour. A disadvantage of the
circular saw is its inability to make more than a single cut at once. When
slabs are to be sawed on both sides the block is returned to a starting
car and carefully aligned for a parallel cut. Both circular and gang saws
are used very widely.

An unusual granite-cutting machine, known as the "Chase" saw,
consists of a series of nine massive steel blades, about 20 inches wide
and M inch thick arranged in tandem, pivoted near the center and swing-
ing back and forth with an edgewise motion actuated by a crank and
pitman. Steel shot are used as abrasive. Granite blocks are mounted
on a traveling bed and joined with plaster of paris in exactly the same
way as for cutting by a circular saw. The machine can saw blocks with a
maximum thickness of about 5 feet, and cuts at a rate of about 2 inches a
minute in blocks 4 feet thick, or about 40 square feet an hour. Like
the circular saw it is limited to single cuts, but its operation is con-

162 THE STONE INDUSTRIES

tinuous. In so far as the writer is informed, only one such saw is now in
use.

Sawing of granite is costly and therefore employed only in preparing
the higher grades of ornamental or structural stone. Though expensive,
sawing has certain definite advantages. Thin slabs which could not be
shaped profitably in any other way are readily obtained. Furthermore,
the most attractive surface on some granites parallels the hard way,
and by ordinary methods of splitting with wedges it is difficult to obtain
blocks having their larger surfaces parallel to this direction, while
sawing may be done as readily in one direction as another.

An important advantage of sawing is conservation of stone. In
splitting with wedges irregularities are bound to occur, and much stone
is wasted in smoothing surfaces, while a saw removes little more than an
inch of material and leaves the surfaces smooth and straight. Such
smooth faces are advantageous in following processes, for sawed slabs
are smoothed with very little labor before polishing. Sawed blocks of
cut stone that have had no surface treatment other than sand blasting
are acceptable to many builders and architects.

Finishing the Surface. — A crude form of granite polishing was known
to the Egyptians, but the art apparently was lost until rediscovered by
granite workers at Aberdeen, Scotland, about 1820. Polished granite
is now used widely for monuments and ornamental building purposes; and
because of its hardness, crystalline character, variety of color, and trans-
parent grain it has superior beauty and endurance. Sawed slabs, or blocks
reduced to uniformity with surfacing machines, are carried through
several stages of treatment before a final polish is attained. The suc-
cessive steps are known in Vermont as "ironing," "emerying," "honing,"
and "buffing." Although different names may be applied in other
States the processes are essentially the same in all granite districts.

IRONING, — Surfaced or sawed blocks are placed in groups of 8 or 10
on a timber bed with their upper surfaces on an even plane. The
rectangular group of blocks is surrounded by a wooden box, with the
bottom a little lower than the surface of the rock. All cracks in the box
and between the blocks are filled with plaster of paris. A worker guides a
belt-driven revolving head over the blocks, and steel shot with water
coming between the rotating head and the stone gradually wear down the
surface. The rotary head, known as a "scroll," is a series of concentric
or spiral iron rings or segments of various patterns, some of which are
broken or notched. The patterns are designed to keep the abrasive
under the scroll as long as possible and to make it cut effectively. For
machines guided by hand scrolls may be 3 or 4 feet in diameter. The
process of thus wearing down a surface with steel shot is known locally
as "ironing." Two beds usually are provided within reach of each
machine, and, while stone on one is being smoothed, blocks are being

GRANITE 163

leveled and set in plaster on the other; thus the machine may be kept
in almost constant use.

EMERYiNG. — The next step, known as "emerying," produces a
smoother finish. It requires a lighter scroll and emery or more com-
monly, Carborundum powder, as abrasive. Three or four grades of
abrasive successively finer in grain size are employed, the coarser being
washed carefully from the surface before the next is added.

BUFFING. — For the final polishing process, generally known as "buff-
ing," a buffer head is operated in the same way as the scrolls. It consists
of a circular disk mounted with numerous folds of paper-mill felt. Putty
powder (extremely fine-grained tin oxide) is added, with a moderate
supply of water. If more than one surface is to be polished the block is
turned and reset in another bed. An experienced worker can completely
polish a bed in 1 day. Small surfaces, and designs in other than flat
surfaces are polished by hand methods or by small machines which will be
described later.

MODIFIED METHODS OF FINISHING SURFACES. — The brief descriptions
already given cover processes that have been long used, but certain
recent changes and improvements deserve mention. Automatic polishers
that require little or no hand work are being used more widely. On some
the rotating scroll is driven back and forth over the length of the bed or
block, its movement being automatically reversed with a trip set in any
desired position.

Another type of automatic polisher travels laterally across a bed
mounted directly on a large car. The car carrying the stone moves back-
ward and forward while the polishing wheel travels crosswise, both
motions being under control of an operator. Such mechanically operated
ironing wheels may weigh 3,000 pounds, and therefore cut very rapidly.
Ironing, emerying, and buffing follow in succession by changing the rotat-
ing heads and the abrasive. Starting with rough, unsurfaced quarry
blocks a final polish may be attained at a rate of about 15 square feet an
hour on one machine.

Much surface finishing is now done without setting the blocks in
plaster of paris. They are merely placed and leveled on a base block in
an enclosed area which collects the splash. A great deal of time is saved
thereby. When plaster beds are dispensed with, provision is made for
mechanical recovery and return to the surface of used coarser abrasive.
A typical mill is equipped with three machines, the first using coarse
silicon carbide, the second four successive grades of fine silicon carbide
or emery, and the third a buffer head. Automatic polishers are employed,
and blocks may be mounted on opposite sides of each machine for
alternate and practically continuous operation. It is claimed that such
equipment will polish about 350 square feet a day. To attain this

164 THE STONE INDUSTRIES

footage, however, sawed slabs only are used, a circumstance which
shortens the smoothing time materially, as it eliminates ironing.

SPECIAL SURFACE FINISHING. — Many blocks that can not conveniently
be placed beneath a regular buffer are polished with special machines con-
sisting of small buffer heads guided over the surface by hand and driven
by small electric motors mounted directly on movable frames. Small,
air-driven, portable polishing disks are used for narrow edges. Curved
or irregular surfaces are polished by hand.

Carborundum Machines. — Specially designed silicon carbide wheels
cut moldings and rabbitts, shape fluted columns, recess panels, and
handle similar processes. They must be operated carefully and with an
abundance of water. The granite block usually is mounted on a traveling
bed that carries it beneath the wheel, which cuts a groove about one-
eighth inch deep at each motion. Some wheel mountings may be reversed
to groove both the top and bottom of a block. On others the crosshead
carrying the arbor unit will swing through an angle of 90° to cut moldings
of any desired inclination. A "contour" machine is a special type
designed to follow a given pattern. The life of a wheel varies; with
fairly constant use one costing $7.50 will last about one day. Car-
borundum machines cut accurately, and provide a very smooth finish;
a single machine accomplishes in a given period very much more than a
cutter using hand tools.

Turning Lathes. — Ornamental granite in sound blocks absolutely free
from incipient seams is widely used for columns. The shaping, turning,
and polishing of columns are a distinct granite-cutting art. The block
first is roughed out to an approximately cylindrical form by drilling,
wedging, shaping with a bull sett, and dressing down with hand hammer
and chisel. Exceptionally, a cylindrical block of granite is cut by means
of a rotating drum fed with steel shot.

The rough cylinder is mounted in a lathe in which it rotates slowly.
One or more steel disks are mounted on axes inclined about 45° to the
axis of the column. The disk is not power-driven but turns freely as its
edge comes in contact with the rotating column. As the disk travels
slowly lengthwise to the column it chips off projections and gradually
works the surface to a uniform cylindrical shape. The column is then
ground smooth with steel shot, followed by emery or other abrasive, and
polished with putty powder on buffing pads held against it as it rotates.

One mill in Barre, Vt., speciaUzes in cutting columns. Large lathes
are provided for turning massive monoliths. Numerous small lathes
are employed for small columns, balusters, and spindles, as well as for
ornamental urns, vases, and flowerpots, which are used principally in
cemeteries. The dimensions and shapes are shown in drawings which for
smaller objects are full size. As turning proceeds, diameters are measured
with calipers, and contours are fitted to patterns. Square bases and

GRANITE 165

caps of columns are cut in the lathe with Carborundum wheels, the
lathe being locked from turning while each cut is in progress. Silicon
carbide wheels also cut grooves in cylindrical objects, the wheel and the
stone rotating at the same time. The turned column is placed in another
lathe for ironing, emerying, and buffing. An iron plate is fitted to
irregular contours, and an abrasive is fed under the plate by hand as the
column rotates. For straight surfaces a flat bar is used; for small,
curved surfaces a piece of iron pipe is held firmly against the rock and
moved back and forth while an abrasive mud is added. Very beautiful
polished objects are thus manufactured.

Surface Finishes. — Granite products have various types of surface
finish. For certain building and monumental uses a "rock-faced"
finish is preferred — that is, a rough broken surface like that obtained
when spalls are broken off with a sledge. Edges of rock-faced surfaces
usually are outlined with a pneumatic tool.

A "hammered" or "axed" finish is obtained by surfacing with a bush
hammer. It shows faint parallel ridges, and the surface is white or very
light. A "steeled" surface is obtained by "ironing" with steel shot. It
is intermediate in smoothness between hammered and polished, for it
shows faintly the color of the rock rather than the uniform white or light
gray of the hammered surface; thus, a steeled Barre granite is bluish.
A polished surface is the most ornamental, for it brings out the color of
each individual surface grain and shows all details of texture. It is also
easiest to clean. Polished granite is used widely for monuments and for
the lower courses, columns, and other prominent parts of large buildings.
A granite that shows a sharp contrast between polished and hammered
surfaces is preferred for monuments, because inscriptions stand out
prominently.

Arrangement of Mills. — In modern granite mills machines are
arranged in logical order, so that blocks travel by the shortest and most
convenient route until they arrive at the point of storage or shipment.
Overhead traveling cranes handle blocks expeditiously. Small cranes
are provided for quick handling of small blocks, while large, powerful,
though slower moving cranes, handle masses weighing up to 40 or 50
tons. The general arrangement and operation of cranes are similar to
those of limestone-finishing mills described in some detail in a previous
chapter. Mills are usually well lighted, heated, and ventilated and are
equipped with suction fans for removing granite dust from machines and
tools.

Storage and Shipment. — Products of granite mills are sold chiefly to
retail monument dealers or to builders and contractors. As large stocks
may accumulate, space must be provided for storage, and equipment
for handling and loading. Monuments and polished building stones are
crated carefully to protect them from damage during handling and

166 THE STONE INDUSTRIES

transportation, and usually stored under cover in such positions that they
may be readily located and conveniently loaded. Polished and carved
surfaces are protected with wrapping paper and sometimes with special
waterproof paper under the crating to guard against temporary stains.
Building granite ordinarily is stored in the open. Sometimes the stone
for an entire structure is cut before any is shipped, which requires careful
planning and arrangement so that blocks may be shipped in the order in
which they are to be placed. On other contracts rock may be loaded for
shipment practically as fast as cut. As granite is a heavy product all
unnecessary handling is avoided.

MARKET RANGE

Finished monuments from the mills of Barre, Vt., are the most widely
distributed in all granites and are marketed in practically every State.
The granites of Quincy, Mass., also are widely distributed. Granite
monuments from St. Cloud, Minn., and from Wisconsin are marketed
largely in the Middle West, although they are used to some extent in
more distant States. The "black granites" of Pennsylvania and New
England are sold chiefly in New York City. Building granites produced
principally near the Atlantic seacoast of New England, and in Penn-
sylvania, North Carolina, Georgia, and California are marketed chiefly
in the larger cities where they are used for entire structures or for
base courses and trim in residences, office buildings, stores, banks,
churches, schools, and other public buildings. An important application
is in bridge construction. For this use it may be shipped for long
distances; for example, Georgia and North CaroUna stone has been used
in large bridges in Philadelphia and New York.

IMPORTS, EXPORTS, AND TARIFFS

About 60 per cent of the imports of unmanufactured monumental
granite is obtained from Sweden. The Swedish granites are chiefly dark
varieties, the so-called black granites. Red granite from Finland is
second in importance. Imports of monumental base stock and building
granite come chiefly from Canada.

Imported manufactured granite consists largely of monument dies
with polished surfaces. The chief imports, which come from Germany,
consist of dies manufactured from Swedish granite. Finland is second in
importance for manufactured as well as for unmanufactured granite.
Imported manufactured granite is purchased for the most part by whole-
sale dealers in Ohio, for sale to retail monument dealers west of the
Alleghenies.

According to tariff classification granite exports are combined with
exports of a number of other commodities and therefore cannot be shown
separately, but the amount is small.

GRANITE 167

According to the Tariff Act of 1930 granite suitable for use as monu-
mental, paving, or building stone, not specially provided for, hewn,
dressed, pointed, pitched, lined or polished, or otherwise manufactured
bears a duty of 60 per centum ad valorem; on unmanufactured granite
the duty is 25 cents a cubic foot.

PRICES

Buifding granite is sold principally on lump-sum contracts. When
sold on smaller contracts random blocks without cutting or carving are
quoted at prices ranging from $1.40 to $2.25 a cubic foot at points of
consumption. Unmanufactured monumental granite is $3 to $4.50 a
cubic foot f.o.b. quarry.

Bibliography

AxjBURY, Lewis E. The Structural and Industrial Materials of California. Cali-
fornia State Min. Bur. Bull. 38, 1906, pp. 23-61.

Bowles, Oliver. Structural and Ornamental Stones of Minnesota. U. S. Geol.
Survey Bull. 663, 1918, 225 pp.

Bowles, Oliver, and Hatmaker, Paul. Trends in the Production and Uses of
Granite as Dimension Stone. Rept. of Investigations 3065, U. S. Bur. of Mines.
1931, 21 pp.

Buckley, E. R. Building and Ornamental Stones of Wisconsin. Wisconsin Geol.
and Nat. Hist. Survey Bull. 4, 1898, 544 pp.

Buckley, E. R., and Buehler, H. A. The Quarrying Industry of Missouri. Mis-
souri Bur. Geol. and Mines, vol. 2, 2d ser., 1904, pp. 60-85.

Coons, A. T. Chapters on Stone. Mineral Resources of the United States, pub-
lished annually by the U. S. Bur. of Mines. (U. S. Geol. Survey prior to 1924,
Minerals Yearbook since 1931.)

Dale, T. Nelson. The Commercial Granites of New England. U. S. Geol. Survey
Bull. 738, 1923, 488 pp.

Eckel, E. C. Building Stones and Clays. John Wiley & Sons, Inc., New York,
1912, pp. 32-68.

Federal Board for Vocational Education. Granite Cutting, An Analysis of the
Granite Cutter's Trade. Bull. 137, 1929, 251 pp.

Merrill, G. P., and Matthews, E. B. The Building and Decorative Stones of
Maryland. Maryland Geol. Survey, vol. 2, pt. 2, 1898, pp. 136-168.

Nash, J. P. Texas Granites. Univ. of Texas Bull. 1725, 1917, 8 pp.

Newland, D. H. The Quarry Materials of New York; Granite, Gneiss, Trap, and
Marble. New York State Museum Bull. 181, 1916, pp. 58-175.

Richardson, C. H. Building Stones and Clays. Syracuse Univ. Book Store,
Syracuse, N. Y., 1917, pp. 38-133.

U. S. Tariff Commission. Granite. Rept. to the President of the United States,
1929, 72 pp.

Watson, T. L. A PreUminary Report on a Part of the Granites and Gneisses of
Georgia. Georgia Geol. Survey Bull. 9-A, 1902, 367 pp.

Granites of the Southeastern Atlantic States. U. S. Geol. Survey Bull.

426, 1910, 282 pp.

Watson, T. L., and Laney, F. B. The Building and Ornamental Stones of North
Carolina. North Carolina Geol. Survey Bull. 2, 1906, 283 pp.

CHAPTER IX

MARBLE

HISTORY

Marble working is an ancient art. Because of its attractive crystalline
form marble was one of the first stones to be used for carving and for
structural purposes. Biblical references to its use in Solomon's Temple
at Jerusalem and the palace of Shushan indicate that it was well-known
for building and decoration more than 1,000 years before the Christian
era. Parian marble was used by the early Greek sculptors in such
famous statues as Venus de Medici, and the Parthenon was built of the
renowned Pentelic marble. Carrara, Italy, has long been a center of
marble production, as well as of art and architecture. We are, indeed,
indebted to the enduring qualities of this stone for preservation of many
magnificant and inspiring examples of sculpture and structural design
that might otherwise have been lost. Numerous invaluable records
inscribed on marble slabs have added to our wealth of ancient history.

DEFINITION

In its geologic sense the term "marble" is applied to rocks consisting
of crystallized grains of calcite, dolomite, or a mixture of the two. Marble
has the same chemical composition as limestone or dolomite, the chief
difference being that the component particles of calcium or magnesium
carbonates in limestone are granular and noncrystalline. It is regarded
as a metamorphic rock resulting from the recrystallization of limestone.

In its commercial sense, the term has a much wider application. As
susceptibility to polish is one of its chief commercial assets, all calcareous
rocks capable of taking a polish are classed as marbles. Furthermore,
serpentine rocks, if attractive and capable of taking a good polish, are so
classed, even though containing little calcium or magnesium carbonates,
as they are commercial substitutes for true marbles.

COMPOSITION

Aside from serpentine and other extraordinary varieties, marble
consists almost entirely of calcium or magnesium carbonates. A calcite
marble may include 95 to almost 100 per cent calcium carbonate. If
impurities are disregarded a dolomite marble contains approximately 54
per cent calcium carbonate and 46 per cent magnesium carbonate. Those
comprising mixtures of calcite and dolomite may have compositions any-

168

MARBLE 169

where between these two extremes. Varying percentages of impurities
are present in practically all marbles. The more common impurities are
silica (Si02), either as free quartz or combined in silicates; iron oxides,
such as hematite (Fe203) and limonite (2Fe203.3H20) ; manganese oxide
(MnO); alumina (AI2O3), in the form of aluminum silicates; and sulphur,
usually as pyrite (FeS2). Small quantities of organic matter may be
present ; in some marbles it has been converted into graphite. Impurities
occur as common minerals, and their presence gives to colored marble the
veins and markings that sometimes adapt it to decorative uses. The
more common mineral impurities are quartz or some other form of free
silica, such as chert or flint, hematite, limonite, graphite, mica, chlorite,
tremolite, woUastonite, diopside, hornblende, tourmaline, and pyrite.
In the marbles of southern Ontario, Parks^* notes the presence of 37
minerals that have been formed by metamorphic processes acting on
the impurities of the original limestone. Impurities in their relation to
use are discussed more fully on pages 175 to 177.

ORIGIN AND VARIETIES

Marbles may be classed in three groups.

The first group, which includes by far the largest proportion, com-
prises those resulting from recrystallization of limestone. Most of them
are highly crystalline and are usually white, though gray, black, or other
markings may be present. A preponderance of the Alabama, Georgia,
Vermont, Massachusetts, Connecticut, and southeastern New York
marbles are -of this type. The original rocks were formed in the sea,
mainly as accumulations of the calcareous remains of marine organisms,
which were consolidated to form coherent rocks termed "limestone."
The origin of limestone is described more fully in the chapter on limestone.
Heat and pressure, usually accompanied by extreme deformation of the
beds, resulted in the highly crystalline condition most commercial
marbles exhibit. Recrystallization as a result of igneous intrusion has
been noted. Fossiliferous or subcrystalline marbles have been subjected
to less extreme metamorphism, and in many instances the original fossils
remain almost intact. They have sufficiently close texture to take a
good polish and at the same time show attractive color effects. Water
probably has assisted greatly in their recrystallization. In fact, some
marbles seem to have been altered from limestones chiefly by circulating
water, for they show no evidence of deformation or extreme pressure, nor
are they near igneous intrusions.

The second group comprises the onyx marbles. These consist
essentially of calcium carbonate and are purely chemical deposits that
have not resulted from metamorphism of preexisting limestone beds.

^' Parks, W. A., Report on the Building and Ornamental Stones of Canada.
Canada Dept. of Mines, Mines Branch, vol. 1, no. 100, 1912, p. 307.

170 THE STONE INDUSTRIES

Such calcareous chemical deposits are of two types. One, which is
regarded as a product of precipitation from hot springs, is termed traver-
tine. As most travertines are porous and can not take a fine polish,
they are classed with limestones rather than with marbles. The other
type, true onyx marble, usually is regarded as a deposit from cold-water
solutions, commonly in limestone caves, hence the name "cave onyx" is
sometimes applied to it. Impurities, such as iron and manganese oxides,
may be present in varying amounts in successive layers of this marble,
and thus beautiful banding may result. This type is commonly known
as Mexican onyx because very fine deposits have been found in Mexico.
Many onyx marbles are semitranslucent.

The third group includes the verde antiques. The name is applied to
marbles of prevailing green color, consisting chiefly of serpentine, a
hydrous magnesium silicate. They are highly decorative stones the
green color being interspersed at times with streaks or veins of red and
white. In no respect are they comparable with true marbles in either
composition or origin. Serpentine is in general derived from the altera-
tion of basic igneous rocks, such as the peridotites which are rich in olivine
and pyroxene, or from magnesium silicate rocks formed by metamorphism
of impure dolomitic limestone. The process is accompanied by hydra-
tion, with an addition of 13 to 14 per cent of water. The movement
occasioned by the swelling that results probably accounts for most of the
unsoundness common to verde antique.

PHYSICAL PROPERTIES

Hardness. — As defined on a previous page, hardness is a measure
of the resistance the surface of a substance offers to abrasion. As given
in Moh's scale the hardness of calcite is 3 and dolomite 3.5 to 4, whereas
window glass is about 6. Marbles are harder than most limestones, for
while they may consist of the same mineral — calcite — grains of limestone
usually are cemented together less firmly, and hardness of a granular
rock is measured by the degree of cohesion between grains rather than by
the actual hardness of the mineral. The presence of such impurities as
flint or silicate minerals may increase the hardness of a marble very
greatly. Hardness of the mass as a whole is an indication of "work-
ability" and is an important property, as the cost of quarrying marbles
that are worked slowly by tools is much higher than that of those easily
worked. Although the cost of quarrying hard marble may be high,
hardness is a desirable property if the material is to be exposed to abrasion.

High resistance to abrasion and uniform hardness are desirable
qualities in marbles to be used for sills, steps, or floor tile, all of which are
exposed to the friction of feet of pedestrians. In constructing floor
patterns of different marbles it is important that they be equally resistant

MARBLE 171

to abrasion, otherwise the floor eventually will become uneven. This
condition may be observed in the Union Station at Washington, D, C,
where tiles of relatively pure calcite marble are worn down in places
nearly half an inch lower than the smaller squares of harder, colored,
siliceous marble.

Specific Gravity and Weight per Cubic Foot. — The specific gravity of a
substance is its weight compared with that of an equal volume of water.
The specific gravity of calcite is 2.7 and that of dolomite about 2.9.
Consequently, dolomite marbles are heavier than calcite marbles. It is
found that the actual weight per cubic foot of a block differs more or less
from its theoretical weight calculated from the specific gravity of the
constituent minerals. A porous rock of given volume will be lighter than
an equal volume of similar nonporous material.

The pore space in most marbles is so small that the actual weight
does not differ greatly from that calculated from specific gravity. Marbles
range from 165 to 180 pounds per cubic foot in actual weight.

Solubility. — The solubility of marble deserves careful consideration if
its use for exterior purposes is contemplated, because all stones dissolve
slowly or disintegrate when exposed to atmospheric agencies. Usually
the rate of solution is extremely slow, but it may be rapid enough under
certain conditions to impair the value of stone for building. The rate of
solution varies in different marbles, depending on chemical composition,
texture, and porosity. Surface waters which contain certain dissolved
gases, such as carbon dioxide, dissolve the carbonates to a limited degree.
Near large cities various acids from smoke are taken up by rain and
increase its power of solution. If a stone is permeable it usually dissolves
more rapidly than if impervious. Calcite dissolves more rapidly than
dolomite under the same conditions if the texture of each is similar, but
the tendency for dolomite to occur with granular texture often reverses
the order of their solubility.

Color. — The color of a marble, one of its most important physical
properties, is governed by the nature of the constituents. Marbles con-
sisting of pure calcite or dolomite are white, whereas green is the prevail-
ing color of verde antique. Variations from the whiteness of a pure marble
are due to admixtures of foreign substances. Such impurities may be
distributed uniformly and thus give uniform coloration or they may be
present in bands or streaks, giving clouded or otherwise nonuniform
colors. Very beautiful banded effects are obtained by sawing veined
marbles in certain directions.

The causes of some colors in marbles are easily determined. Black
and grayish shades are attributed to carbonaceous matter, which is
usually present as fine scales of graphite ; red, pink, or reddish brown are
due mainly to the presence of manganese oxides or to hematite; yellow-
brown, yellow, or cream are caused by minute grains of limonite, a

172 THE STONE INDUSTRIES

hydrous oxide of iron. Other colors, such as the bluish tint found in
some beds of white marble, are difficult to explain.

Highly colored marbles are usually those that have been brecciated
or fractured, subsequent consolidation being accompanied by infiltration
of coloring material from surrounding soil and rocks. They are mostly of
foreign origin.

For certain purposes, particularly for monuments on which inscrip-
tions are cut, marble which presents a distinct contrast between chiseled
and polished surfaces is desirable. A chiseled surface is opaque and
somewhat granular and reflects rather than absorbs light ; hence it tends to
appear white or light-colored, even if the stone is dark. When a face is
polished the reflecting surfaces are removed, and light is permitted to
enter the crystals and be absorbed, which causes the polished surface to
appear relatively dark. The contrast usually is more pronounced in
colored and less marked in the white marbles.

Each bed in a deposit exhibits more or less constancy of color; there-
fore, desirable uniformity in color ordinarily can be maintained by
working each bed separately. If the texture or color of marble in a
deposit varies, care is taken to quarry in such manner as will tend to
produce material that may be closely classified. Some variations in
color, though slight, may detract immensely from the market value.
Lenses and bands of bluish material may pass irregularly through the
white, occasioning excessive waste or necessitating classification in a
lower grade.

Colors may be permanent or may change after exposure to sunlight or
weather, the more highly colored marbles being most subject to such
changes. Severity of climate is an important factor in these changes.
Permanence of color is highly desirable. Most high-grade American
marbles show very slight color alteration even after long periods. A
soiled surface must not, of course, be confused with color changes.

Translucence. — Translucence is a measure of the capacity of marbles
for transmitting light. The more translucent varieties, if fine-grained,
are best-adapted for novelties or other ornamental purposes. Some
marbles look waxy, and this property seems to be related to translucence.
The depth to which light will penetrate the best statuary marbles ranges
from }yi to 13-^ inches. Certain beds in many marble deposits of the
United States are exceptionally translucent. The beautiful so-called
"transparencies" in the roof of the Lincoln Memorial at Washington,
D. C. are translucent slabs of clouded and veined Alabama marble.
Certain modes of artificial treatment are known to increase translucence,
but usually the effects of such treatment are far less permanent than the
material itself and consequently are not to be recommended.

Texture. — Grains of calcite and dolomite that make up a marble mass
are crystalline and have a definite cleavage, showing bright reflecting

MARBLE 173

faces on a broken surface. Usually the cleavages appear about equally-
prominent in every direction. In some marbles, however, the grains
are elongated in one direction by the folding or plication of beds. Most
marbles consist of a single mineral, and therefore have a homogeneity
that is favorable for resistance to weathering because of uniform expansion
and contraction with temperature changes. The texture of a marble
thus depends on the form, size, uniformity, and arrangement of its grains,
and on the nature and size of grains of accessory minerals.

The size of grain is commonly described as fine, medium, or coarse.
Such terms are indefinite and may have quite different meanings, the
interpretation depending upon the range of texture experienced by the
observer. To place texture upon an absolute basis Dale graded
the marbles of Vermont into six classes, based upon average grain
diameter, as follows: Extra fine, 0.06 millimeter; very fine, 0.10; fine, 0.12;
medium, 0.15; coarse, 0.24; and extra coarse, 0.50.

Rift or Grain. — While the terms "rift" and "grain" have distinctive
meanings as applied to sandstone and granite, in connection with marble
they are used synonymously for the direction of easiest splitting. The
rift usually parallels the bedding, and it is probably due to elongation
of grain caused by pressure. It may be emphasized by the presence of
platy or fibrous minerals, such as scales of mica or graphite or needles of
actinolite. These usually occupy positions with their long axes parallel
to the direction of grain elongation and thus increase the tendency to
split in that direction. Quarrymen find it advantageous to follow the
direction of easy splitting, for thus wedges may be placed much farther
apart than where no rift exists.

Porosity. — Porosity is the volume of pore space expressed as a
percentage of the total volume of a rock mass. The pore space of high-
grade marbles is usually very small, ranging from 0.0002 to 0.5 per cent.
A fine-grained marble may have more pore space than one of coarser
texture, but the opposite is more often true. Low porosity in exterior
marble is desirable, as pores permit infiltration of water, which may dis-
solve or discolor the stone or cause disintegration by freezing. Porous
stones also collect soot or particles of soil and therefore are not
satisfactory when exposed to excessive smoke or dust. Practically all
marbles recommended for exterior use have very low porosity.

Strength. — The strength of marble is the measure of its capacity to
resist stresses of various kinds. It depends partly on the rift, on the
cleavage and hardness of the grains, and partly on the state of
aggregation, including degree of cohesion, interlocking of grains, and
nature of cementing material if such is present. Compressive, transverse,
tensional or cohesive, and shearing strength all affect use, but compres-
sive strength is the quality most commonly tested.

174 THE STONE INDUSTRIES

Although strength alone is not a sure criterion of durability, knowledge
of the capability of any stone to withstand stresses of various kinds has
great value if the material is to be used for purposes involving extra-
ordinary strains. Practically all commercial grades of sound white
marbles can support many times the weight of structures in which they
are ordinarily used, though some brecciated and veined marbles are too
weak to sustain heavy loads with perfect safety. As a rule, marble is
stronger across the bedding plane than parallel to it. Compressive
strength has no significance in judging the quality of cemetery memorials.

Transverse strength indicates the suitability of a marble for door or
window caps or for bridging material that must bear heavy loads. Break-
age of caps, however, must not always be attributed to weakness in the
material employed, as unequal settling or improper laying may be the
chief cause.

When subjected to crushing strain rocks can be compressed appreci-
ably before rupture occurs. A measure of this compressibility in terms
of the load is what is known as the modulus of elasticity. The compressi-
bility of marble is so small that it has little significance, except possibly
in calculating the effect of a very heavy superstructure on a masonry
arch or in proportioning abutments and piers of massive bridges, A high
modulus of elasticity is desirable in marble subjected to minor stresses
and strains due to setthng of buildings.

JOINTING OR UNSOUNDNESS

Meaning of Unsoundness. — The term "unsoundness" refers to all
cracks or lines of weakness other than bedding planes that cause marble
to break before or during manufacture. The various types are known
locally as "joints," "headers," "cutters," "hairlines," "slicks," "seams,"
"slick seams," "dry seams," or "dries," and "cracks." The term
"reed" is applied to a weakness that parallels the bedding.

Nature and Importance of Joints. — Most joints, as they appear in
marble deposits, are straight and uniform, though some may be curved or
irregular. Some are open and conspicuous and others so obscure that
they can be recognized only by long and constant practice on the part of
those skilled in their detection. The spacing of joints is variable. They
tend to occur in groups of closely spaced fractures, separated by masses
which contain few joints. In certain Vermont quarries such closely
spaced groups are termed "fish-backs." In some deposits joints may be
10 to 30 feet apart, in others, separated by only a few inches. Needless
to say, wide spacing adds greatly to the commercial value of a deposit.

Origin of Joints. — Authorities generally agree that joints are caused
by strains in rock masses. As pointed out in the chapter on granite, a
compressive force in one direction will develop two systems of joints at
right angles to each other, and at angles of 45° to the line of pressure.

MARBLE 175

Torsional forces or earthquake shocks alone or in conjunction with other
forces may have a similar effect. Both direction and spacing, as observed
at the surface, may persist with remarkable uniformity at depths of 100
feet or more.

Therefore, according to the theory noted in the paragraph immedi-
ately preceding, which is supported by results of many observations,
joints tend to occur in regular systems. Two systems approximately at
right angles to each other are not uncommon. Occasionally a third or
fourth system may appear. Exceptionally no well-defined systems can be
recognized. The systematic arrangement is recognized by most quarry-
men and is an important factor in the economy of marble working.
Greater loss results from quarrying without regard for unsoundness than
from any other cause. Operators may augment the proportion of sound
stock by making careful study and detailed diagrams of all visible
unsoundness and by quarrying in conformity with it. That is, walls
should be made to parallel the major joint systems, and all subsequent
cuts so arranged in spacing and direction that seams will intersect blocks
as little as possible. Blocks intersected by oblique joints are almost
useless.

Unsoundness in Verde Antique. — Joints in serpentine marble, or
what commonly is called "verde antique," usually are rather abundant
and extremely irregular. They are probably caused chiefly by expansion
or swelling due to hydration as the serpentine is formed. Consequently,
joints are usually less systematic in this variety than in white marbles,
and large, sound blocks are more difficult to obtain. Occasionally the
cracks are recemented by crystalline calcite, which produces an attractive
white veining on a green background. The so-called brecciated marbles
are composed of many irregular and usually angular fragments that have
been cemented by chemical precipitation of calcium carbonate.

Glass Seams. — Joints that have been recemented in nature are
sometimes termed "glass seams." They may be strong enough to
permit sawing the marble even into thin stock, but such seams are usually
planes of weakness. The filling is generally calcite, though occasionally
silica in the form of quartz, flint, or chert. A siliceous filling is least
desirable because its extreme hardness makes sawing and polishing
difficult, and because its surface is nonuniform. In any case, a glass
seam usually appears as a conspicuous line which can be regarded only as a
blemish when present in otherwise uniform marble.

CHIEF IMPURITIES OF MARBLE

Iron Sulphides. — The chief iron sulphides in marble are pyrite and
marcasite, which have the same chemical composition (expressed by
the formula FeS2), though they differ in crystal form. In many marble

176 THE STONE INDUSTRIES

deposits they are accessory minerals, pyrite being the more common,
and may appear as scattered crystals of variable size or form prominent
bands and masses. Decomposition of the sulphides may result in undesir-
able discolorations, consisting of iron oxides.

Most authors who have discussed impurities in building stone have
stated unreservedly that pyrite is injurious when the stone is used for
exterior work. This statement is not always true, however. Although
the sulphides in some marbles decompose and form undesirable dis-
colorations in a few months, those in marble from other deposits may
withstand many years of weathering and show no appreciable change.
Some American marbles containing pyrite have been exposed to the
weather for more than 100 years without noticeable staining.

Pyrite is usually more stable than marcasite. Solid crystals of either
mineral usually decompose slowly, though finely divided granular or
porous forms of either alter rapidly. Mixtures of pyrite and marcasite
decompose more readily than the pure minerals. A fair conception of
the probable stability of the sulphides in a marble may be gained by
making observations and tests. The most reliable information is obtain-
able by observing stain effects on structures of sulphide-bearing marble
or on weathered outcrops of the deposit from which it was obtained.
Iron sulphide is not necessarily injurious in marble but should be avoided
carefully in the selection of stone for exterior uses where discoloration is
undesirable. In some instances, however, discoloration by weathering
may not be detrimental, for such color changes may blend with the normal
mellowing and ageing of the stone.

Marble containing pyrite may be used to advantage for interior
structural or ornamental purposes, as bands and patches of the iron
sulphide minerals produce beautiful effects on polished surfaces. Pyrite
crystals are very hard, however, and may injure tools used in cutting.

Silica. — Knots or bands of silica derived from skeletal remains of
organisms may be original constituents of marble. Silica may also be
introduced into a marble bed at a later stage in the history of the deposit.
Water that percolates through fissures in the mass may contain small
quantities of silica in solution, which may be precipitated in cracks and
cavities. Silica in this form tends to follow unsoundness and may even
effectually seal fractures. The presence of silica usually detracts from
the appearance of marble. As a rule, the flinty or cherty mass differs
from the marble in color or texture and constitutes a blemish comparable
to that produced by a knot in an otherwise uniform stick of timber.
Occasionally, however, flinty masses are the basis for distinctive decora-
tive markings that are an asset to the stone. Silica is at least twice as
hard as ordinary marble, consequently, it greatly retards channeling,
drilling, or sawing and injures tools, especially wire saws. A flint ball
may divert a saw to one side or may greatly reduce the rate of cutting.

MARBLE 177

Moreover, uniformity of finish under a buffer is difficult to obtain on the
surface of a flinty marble on account of its unequal hardness.

Silicated Marbles. — Silicated marbles contain pyroxenes, amphiboles,
mica, chlorite, or other silicates which are commonly formed by alteration
of interbedded impurities. Marbles may therefore contain bands of these
minerals, which sometimes remain conformable with the original bedding.
In such form they are not serious imperfections and may even facilitate
quarrying. However, silicate impurities, especially mica and chlorite,
may be scattered throughout the mass in dark bands and patches which
generally detract from the market value of the stone although at times
they may be adapted to ornamental use.

Dolomitic marbles may contain tremolite, a silicate of calcium and
magnesium. The mineral generally occurs in the form of white crystals
with a silky luster and a characteristic diamond-shaped cross section.
They may be microscopic in size or may attain a length of 2 inches, and
are much harder than marble. Wollastonite, diopside, olivine, and
tourmaline are other common silicates present in marbles.

Dolomite in Marble. — Marble composed of alternating masses of
dolomite and calcite is undesirable. When dolomite is present in lenses
or bands, the resulting unequal weathering will produce a nonuniform
surface. Differences in texture, color, or susceptibility to polish of the
two minerals are also probable. Although pure dolomite, or intimate
mixtures of dolomite and calcite, is not to be regarded as an inferior
type of marble, heterogeneous mixtures in the form of lenses, knots, or
bands are undesirable for the reasons given.

GEOLOGIC INTERPRETATIONS

Intimate knowledge of the geology of marble deposits is a practical
necessity for intelligent quarry development. Beds of high quality must
be followed, and this demands an understanding of their stratigraphy,
including folding and faulting. The origin and occurrence of imperfec-
tions should be known. Operations also depend upon rock structures,
such as joints and dikes.

The quality of a marble tends to be fairly constant throughout a
given bed over wide areas. An adjoining bed, even though only a few
feet away, may have been deposited much later or earlier and under
vastly different conditions. Therefore, the greatest changes in quality
and character of rock are found in passing from one bed to another.
To obtain high quality and uniformity in the product the bedding must be
followed closely. Each bed generally is designated by a particular name,
and quarrymen usually are so familiar with characteristics of successive
strata that they can assign a block in a stock pile to its proper bed by
visual examination. This intimate knowledge of stratigraphy is exceed-
ingly practical in recognizing desirable beds in new openings made along

178 THE STONE INDUSTRIES

the strike or in outcrops where beds reappear at the surface through
folding or faulting. Certain beds may be traced for many miles and may
maintain remarkable uniformity in quality and thickness. They may,
however, narrow, widen, or disappear entirely, and the quality may
change.

USES

Marble is used mainly for buildings and monuments, interior decora-
tion, statuary, and novelties.

In exterior building marbles qualities of endurance rank equally in
importance with appearance. For such outdoor uses, therefore, marbles
should be strong, uniform, close-grained (though not necessarily fine-
grained), reasonably nonabsorptive, and free from impurities that may
stain or corrode the surface. While uniformity in color was once desir-
able, the present tendency is toward blending of mixed colors.

For interior decoration, appearance is the prime factor determining
value. Both pure white and variously colored marbles are applied to the
various uses, including floors, steps, baseboards, columns, balusters, wall
panels, wainscoting, and arches. That used for floors and stair treads
should be reasonably resistant to abrasion. Brecciated marbles, most of
which are imported, are widely used for columns and wainscoting.
Verde antique is popular for interior decorative effects. It is used some-
times as an exterior ornamental stone as, for example, on banks and store
fronts. Onyx marble is popular for interior decoration, as it has a wax-
like appearance and attractive banding. Interior marble is used in
various minor ways, such as for table tops, lavatory fittings, and sanitary
work generally.

Statuary marble is the most valuable variety quarried. It must be
piire white, uniform and usually fine-grained in texture, and somewhat
translucent, and must have marked adaptability for carving. Numerous
statuary and decorative marbles from American quarries are now on the
market, each having its own particular trade name.

All the more ornamental types are used for novelties. A favorite
use of onyx is for the manufacture of gear-shift balls. Onyx, verde
antique, and true marbles are manufactured into inkwells, lamp bases,
smoking sets, clock cases, paperweights, and various other gift-shop
novelties.

Waste marble is used as crushed stone, terrazzo, stucco, and riprap,
for lime, for fluxing, and for various chemical uses covered in a later
chapter on limestone. Waste blocks are also cut into convenient sizes
for ashlar used in house construction.

DISTRIBUTION OF DEPOSITS

As recrystallization, the outstanding characteristic of marble, is
promoted chiefly by heat and pressure acting on the original limestone,

MARBLE

179

most marbles are confined to areas of extreme folding or igneous intrusion,
hence, occur chiefly in mountainous regions. The important marble
belts of the United States are in the Appalachian region of the Eastern
States and in the Rocky Mountain and Coast Ranges of the West.
Deposits also occur in several Central States and in Alaska.

The Appalachian belt, which is the most productive, follows a com-
paratively narrow, well-defined course as shown in figure 29. Beginning
at the Canadian border in northern Vermont it extends due south
through western Massachusetts and Connecticut and eastern New York
to within a short distance of New York City. No marble of consequence

Fig. 29. — Map showing marble deposits of eastern United States. (Prepared by H. Herbert

Hughes.)

occurs in New Jersey, except in the extreme west, but the belt reappears
prominently in southern Pennsylvania and extends southwestward
through Maryland, Virginia. North Carolina, Tennessee, Georgia, and
Alabama.

Marbles of the Central States occur in isolated localities, principally
Minnesota, Missouri, and Texas. For the most part, recrystallization
has been accompanied by very little, if any, deformation of beds.

Various types of marbles are found in the Rocky Mountain and
Pacific Coast States (in parts of California, Nevada, Montana, and
Colorado, with more restricted areas in Idaho, southwestern Oregon, and
northeastern Washington) but many are too inaccessible to have com-
mercial importance at this time.

180

THE STONE INDUSTRIES

PRODUCTION

The volume in cubic feet and value of marble sold in the United
States over a period of years are shown in the following table by uses:

Marble Sold by Producers in the United States, 1924-1937, by Uses

Building stone

„*„1 „4

Total

Year

Exterior

Interior

Cubic
feet

Value

Cubic
feet

Value

Cubic
feet

Value

Cubic
feet

Value

1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937

852,940

1,145,690

1,123,990

850,470

1,019,490

924,420

772,920

594,710

863 , 690

760,420

190,060

150,560

373,520

284,500

$2,621,088

3 , 559 , 686

3,350,434

2,826,079

3,146,202

3,849,510

2,685,924

2,986,901

2,213,673

2,396,571

523,033

494,097

1,701,864

938,570

1,753,240

1,719,610

1,743,950

1,973,320

2,005,150

1,854,380

1,698,180

1,066,640

818,160

583 , 890

309,950

217,890

398,440

447,200

$6,178,131
6,040,425
6,069,505
7,913,149
8,963,125
8,276,206
6,390,107
4,855,595
3,413,929
2,481,167
1,196,423
1,212,173
2,079,010
2,397,975

1,230,450

1,176,090

1,095,220

1,127,480

1,031,050

1,065,760

879,270

637,830

432,590

426,300

464,910

300,370

374,520

360,580

$3,858,190
,3,598,907
4,047,857
4,097,249
3,749,269
3,885,481
3,263,383
2,177,656
1 , 669 , 689
1,358,770
1,475,426
1,521,681
1,751,947
1,798,176

3,836,630
4,041,390
3,963,160
3,951,270
4,055,690
3,844,560
3,350,370
2,299,180
2,114,440
1,770,610
964,920
668 , 820
1,146,480
1 , 092 , 280

$12,657,409

13,199,018

13,467,796

14,836,477

15,858,596

16,011,197

12,339,414

10,020,152

7,297,291

6,236,508

3,194,882

3,227,951

5,532,821

5,134,721

Marble Sold by Producers in the United States, 1929, by States and Uses

Building and monu-
mental (rough and
finished)

Other uses

Total

State

Cubic feet

Value

Short
tons

Value

Short
tons
(approx-
imate)

Value

Alabama

California

Georgia

Massachusetts ....

Missouri

New York

Tennessee

Vermont

Other States*

52,900

14,260

676,190

19,720

477,010

51,220

1,312,180

1,185,100

55,980

$ 381,781

71,259

3,739,825

97,910

927,530

129,202

5,678,596

4,763,471

221,623

36,400
1,570
26,300
2,510
15,900
44,160
58,950
29,350
14,490

S 61,738

9,575

37,450

3,542

4,941

187,760

60,408

35,242

133,459

40,900

2,780

82,920

4,180

55,420

48,640

169,630

129,940

19,250

$ 443,519

80,834

3,777,275

101,452

932,471

316,962

5,739,004

4,798,713

355,082

3,844,560

$16,011,197

229,630

$534,115

553,660

$16,545,312

* Alaska, Arizona, Arkansas, Colorado, Idaho, Maryland, Montana, New Jersey, North Carolina,
Utah, Virginia, and Washington.

MARBLE 181

The eight leading States, in order of production value in 1929, were
Tennessee, Vermont, Georgia, Missouri, Alabama, New York, Massa-
chusetts, and California. The preceding table, compiled by the Bureau of
Mines, shows the total marble production during 1929 by States. These
figures are given in preference to those of later years, when conditions
were more disturbed.

In 1929, 111,580 cubic feet of verde antique (serpentine marble),
valued at $842,058, was sold in the United States; in 1930, 98,490 cubic
feet, valued at $695,131; in 1931, 39,150 cubic feet, valued at $218,098;
and in 1937, 16,300 cubic feet, valued at $145,136.

INDUSTRY BY STATES

Occurrences of marble in the United States are described in the
following pages by States in order of their production value in 1929, as
that year was probably more nearly normal than the three succeeding
years. Descriptions are confined chiefly to deposits in which quarries
have been recently in operation, minor attention being given to unworked
areas or abandoned quarries.

Tennessee.-* — As the preceding table indicates, in 1929 Tennessee
produced 1,312,180 cubic feet of building and monumental marble, valued
at $5,678,596, or about 35.5 per cent of the total value of marble produced
in the country. Production in 1930 was 1,019,300 cubic feet, valued at
$3,355,673; in 1931, 525,900 cubic feet, valued at $2,407,878; and in 1937,
267,370 cubic feet, valued at $1,384,961.

General Distribution. — The widely known marbles of east Tennessee
occur in rocks of Palaeozoic age in what is known as the Holston member
of the Chickamauga formation. The latter formation is of wide extent
and consists chiefly of limestone. The Holston beds are confined to the
Tennessee River Valley and outcrop in a series of nearly parallel bands.
The area is 12 to 16 miles wide and over 125 miles long. Marbles of
commercial quality occur in many places, and the supply is practically
inexhaustible. Two important railway lines traverse the area — the
Southern Railway, which extends throughout its length, and the Louis-
ville & Nashville Railway, which crosses it.

Tennessee marble was used locally for tombstones in very early days ;
but the history of production as an industry dates from 1838, when the
United States Government opened a quarry in Hawkins County to
provide interior marble for the Capitol at Washington. During ensuing
years other quarries were opened until an industry of great magnitude was
developed.

^^ Data on Tennessee marble deposits have been compiled chiefly from Tennessee
Geol. Survey Bull. 28, Marble Deposits of East Tennessee, by Gordon, Dale, and
Bowles, as recorded in the bibliography at the end of this chapter. This information
was supplemented by that obtained during visits to most of the quarries by the
author.

182

THE iSTONE INDUSTRIES

The belts of the Knoxville district are shown in figure 30, which is
modified from Gordon's index map.^^ The seven belts shown in the
figure lie in approximately parallel positions running southwest and
represent a series of folds resulting from lateral pressure exerted northwest-
southeast. Named in order, from northwest to southeast, they are : Luttrell
belt. Black Oak belt, Concord belt, Knoxville belt, French Broad belt.
Meadow belt, and Bays Mountain belt. The Galbraith belt in Hawkins
County is regarded as a continuation of the Black Oak belt. The
Meadow belt was described later than the others and does not appear in
the sketch. Although some good marble is quarried near the boundaries

Fig. 30. — Map showing marble deposits of eastern Tennessee.

of the formation, by far the best and most productive quarries are those
near the middle of the area.

Luttrell Belt. — The Luttrell belt about 55 miles long extends from
Hawkins County southwestward without interruption to about 8 miles
north of Knoxville. As it fringes the northwestern boundary of the
basin, it contains much earthy and shaly matter. Good marble abounds
in many places; but owing to narrow outcrops and heavy stripping,
conditions do not favor development.

Black Oak and Galbraith Belt. — The Black Oak belt begins at Corryton
and extends southwestward through Fountain City to a point about 5
miles northwest of Knoxville, where it is interrupted by faulting and

" Work cited, p. 27.

MARBLE 183

erosion. It reappears 6 miles farther on and continues into Monroe
County. Near Corryton the outcrop is one half to three fourths mile
wide, but throughout the remainder of its course rarely exceeds one
fourth mile. Many impure limestone and shale beds appear with the
marble.

A northeastern extension known as the Galbraith belt occurs in
central Hawkins County and in near-by Virginia. Folding at this point
has been so great that the beds are overturned, bringing the Knox
dolomite above the marble, which occurs in massive layers and is pre-
dominantly dark red or chocolate. Splashes of white in places represent
crystallized remains of bryozoans, corals, and other organisms.

Numerous quarries have been opened in this area, and some are the
oldest in the State. The Dougherty or National quarry supplied stone
for the United States Capitol. Much of the marble was used for table
and dresser tops, but with the decline of this fashion and a growing
demand for pink and gray, production has ceased in this vicinity.

Concord Belt. — The southwestern extremity of the Concord belt is at
Sweetwater, whence it extends northeast past Loudon, Lenoir City, and
Concord through the northern outskirts of Knoxville and ends near
Strawberry Plains in a closed loop about 4 miles across. In general,
earthy and shaly beds are less prominent than in the belts to the north,
while the marble becomes proportionally thicker, except in a section near
Knoxville where the belt is thin. The Southern Railway follows this belt
closely throughout its entire length, and in several places the Tennessee
River intersects it.

Knoxville Belt. — The KJnoxville belt, where much excellent marble is
quarried, appears several miles southeast of Sweetwater, Monroe County,
and extends northeast through Friendsville, Louisville, and southern
Knoxville to the vicinity of Ruggles Ferry on the Holston River. Near
the two extremities of the belt the rocks dip southeast at an angle of
about 30°, but near Louisville they lie more nearly horizontal. This
accounts for the wide outcrop which appears just beyond the northern
corner of the Friendsville area, as shown on the map. Many quarries
have been opened on the belt from the railway station at Meadow to the
northern extremity. The prevailing marble is a popular shade of pink,
with smaller quantities of chocolate and gray.

French Broad Belt. — The French Broad belt is shaped like a great
U, with its base about 3 miles southeast of Knoxville and its sides extend-
ing northeast 8 or 9 miles. Locally it is sometimes called the " wishbone."
The shape is due to the planing off by erosion of a southwestern pitching
anticlinal fold. The northern arm of this fold is the center of a thriving
quarry industry. The marble formation is about 300 feet thick, and
about half is of commercial grade. Several active quarries are situated
near the junction of the Holston and French Broad Rivers.

184 THE STONE INDUSTRIES

Meadow Belt. — The Meadow belt, which is not shown on the map as a
separate band, is quite close to the Knoxville belt. It has been traced
from near Miser southwestward to a point beyond the railway station at
Meadow, at which place it has been quarried to some extent.

Bays Mountain Belt. — This, the southernmost of the marble belts,
is situated along the north side of Bays Mountain 5 to 7 miles southeast
of Knoxville. It is chiefly in Knox County, though it extends a short
distance into Blount County. The widest outcrop is near Neubert
Springs, where the exposure forms the base of a U-shaped loop which
opens to the southwest as the result of the planing off by erosion of a
northeast-pitching anticlinal fold. As this belt is near the southern
boundary of the marble basin it contains more silty and shaly materials
than the central belts. The beds have a maximum thickness of about
300 feet.

Productive Areas. — The Hawkins County area, which is now unpro-
ductive, has been described briefly in the section devoted to the Galbraith
belt. The five productive areas outlined in rectangles on the sketch
map, figure 30, and designated 1, 2, 3, 4, and 5, are briefly described in
order as follows.

LUTTRELL AREA. — The Only important quarries are at Luttrell and
are situated on the lowest bed of the Luttrell belt. This bed is about 75
feet thick and dips 32° in a direction S.35°E. Mud seams 12 to 20 feet
apart run N.50° to 55°E. A series of seams or cutters spaced at moderate
intervals runs N.60° to 80°W. A light red shading into dark red marble
of good quality is obtained, and waste is burned into lime.

CONCORD AREA. — Several quarries are, or have been, in operation
near Concord on the Black Oak, Concord, and Knoxville belts. A
quarry which was at one time of considerable importance is on a westward
continuation of the Black Oak belt about 3 miles north of Ebenezer.
It was opened on a shallow synclinal fold, and the relatively thin
layer of overburden and nearly level attitude of the beds offered favorable
quarry conditions. The main ledge is a 50-foot bed of light pink marble
with heavy ledges of dark red or "cedar" marble above and below.
Originally only the dark red was quarried, but later both types were
marketed. A prominent series of nearly vertical seams or cutters runs
N.40°W. They are spaced 8 to 20 feet apart throughout most of the
quarry.

The most prominent beds quarried at Concord are 75 to 80 feet thick,
with deep red or chocolate marble in the upper part and light red shading
to pink in the lower. The beds dip 30° to 40°, while irregular mud seams
are nearly fiat or slant at a moderate angle. The quarry is near the
river, and in early years much of the product was shipped by water. A
large part of the waste marble has been burned into lime.

MARBLE 185

For many years several quarries were worked about 43-^ miles south
of Ebenezer, but only one has been in operation recently. It is an
important producer and provides an attractive grade of pink marble
known to the trade as ''Bond Pink."

FRiENDSviLLE AREA. — The productive area on the Knoxville and
Meadow marble belts extends from the station at Meadow to Louisville;
Friendsville is about the middle of the district. In this area about 26
active and abandoned quarries have been noted, but not more than five
or six have produced during recent years.

The most southerly active quarries are about 1^ miles west of
McMullen station, where very sound marble occurs in beds about 120
feet thick, the upper 50 feet being red and the remainder light pink to
gray. The principal development has been during the past few years,
and much high-grade marble is now produced.

About 11^ miles east of Friendsville is a second group of active
quarries. As sound, attractive marble is available in large blocks, this is
the most productive part of the district. Pink and red marbles are most
abundant, although gray is also found. The most southerly of the three
openings uncovers beds about 75 feet thick, and the best grade is found in
the lower 25 feet. The marble, covered with a moderate overburden
of sandy soil, dips under the hill at an angle of about 15°. Many mud
seams appear near the surface, but cutters in the rock are rare. At the
second and third openings to the north the overburden becomes much
heavier, and underground methods employing modern electric-driven
equipment are used. Part of the waste is ground and sold as agricultural
limestone. Two miles west of Louisville a similar pink marble is quarried,
and is marketed under the trade name "Anderson Pink." It is of good
quality and available in large, sound blocks.

KNOXVILLE AREA. — The Knoxville area, occupying the center of
the marble valley, is about 3 miles wide and 6 miles long and extends
northeastward from Knoxville along the valley of the Tennessee River
beyond the junction of its tributary streams, the Holston and French
Broad Rivers. An abundance of high-grade rock is available in this
territory and usually at least a dozen quarries are in active operation.

About 43^-^ miles east of Knoxville the deposit is extensive and has
been worked for many years. A group of quarries provides high-quality
light pink and gray marbles, which are well-suited for structural uses and
for carving. Much of the waste is burned into lime. These quarries
are on the northern limb of the French Broad belt, which extends east-
ward through the loop of the river at the Forks. East of the Forks is an
important group of quarries extending about 2 miles east of the river,
where good-quality pink and gray marble is quarried by several companies.
In places, fissures and solution cavities increase the difficulty of quarrying.
The Knoxville belt to the north provides another important quarry area,

186 THE STONE INDUSTRIES

particularly in the section between the Tennessee and Holston Rivers,
\}/2 to 4 miles northeast of Knoxville. In the western part of this section
the beds are 150 to 200 feet thick, with pink marble in the bottom, gray-
above, and some of the darker reds near the top. The chief output is of
the light gray type, which is very attractive for interior decoration.
The quarries farther east produce high-grade, light pink marbles.

NEUBERT SPRINGS AREA. — Marble has been quarried to some
extent on the Bays Mountain belt near Neubert Springs about 8 miles
directly southeast of Knoxville. The bed dips about 75°, an unusually
high angle in the Tennessee district. This area is close to the southern
fringe of the marble valley, so an excessive amount of impure material is
mixed with the good marble. Although pink and gray marbles of good
quality are available, the proportion of waste is high.

Characteristics of Tennessee Marbles, joint systems. — Two com-
plementary sets of major joints prevail throughout the region, one set
striking N.40°-60°E., and the other N.40°-60°W. Weathering tends
to follow the joints, forming solution cavities which have been filled
with residual reddish clay. When the clay is removed the marble
surface in some districts consists of irregular prongs 5 to 20 feet high and
2 to 10 feet apart at the base. As solution tends to follow all planes of
weakness the prongs usually consist of sound high-grade marble. Opera-
tions on these irregular surfaces are known locally as "boulder quarries."

fossil content. — Tennessee marbles consist mainly of calcareous
remains of two kinds of marine invertebrates — crinoids and bryozoa.
Secondary crystallized calcite encloses the crinoidal fragments and fills
the bryozoan cells, as well as all the interstices. Unlike most marbles
those of the Knoxville district are not highly metamorphosed, and multi-
tudes of fossils show no distortion, recrystallization evidently having
involved only slight deformation.

"crowfoot" structure. — The most characteristic structures of
Tennessee marbles are the stylolites known locally as "crowfoot."
They are irregular or zigzag grayish, black, greenish, or reddish suture
planes. The markings, which occur in bands usually 3^f o to 1 inch wide,
generally parallel the bedding and are from a few inches to several feet
apart. These irregular markings appear prominently on marble steps,
floor tile, and wainscoting in innumerable public buildings throughout the
country. The origin of stylolites is somewhat obscure. It is assumed
that they consisted originally of thin bands of carbonaceous and iron-
bearing shales. Percolating acid waters attacked the beds above and
below the shale, dissolving the marble and leaving very irregular surfaces.
The pressure of overlying strata, or that occasioned by folding, forced
the beds together, and with intermeshing of projections above and
below the shale was pressed into all irregularities. Later faulting and
dislocation made the crenelations even more irregular.

MARBLE 187

TEXTURE. — In general, Tennessee marbles consist of calcite grains in
a groundmass of disintegrated bryozoa. Most of them are fine-grained,
but owing to the presence of larger scattered fossils many are variable
in texture. In all but the coarse, dark marbles of Hawkins County the
crinoidal remains, with the secondary calcite about them, make up
approximately one third of the rock and the bryozoa about two thirds.
Because of the fineness and irregularity of the groundmass the rock is
much stronger than uniformly crystallized marbles.

Physical Properties. — Dale-^ has divided Tennessee marbles into six
groups on the basis of color, as follows: (1) Gray; (2) faintly pinkish gray;
(3) pink ^subdivided into light, medium, and dark); (4) fine dark red; (5)
coarse dark red; and (6) variegated. The gray and pale pink varieties
are used most widely. The marbles are of a high degree of purity, with a
calcium carbonate content of about 99 per cent. Even those of chocolate
color have an iron content of not more than 0.5 per cent. Chemical
purity is attributed to the almost exclusively organic origin of the cal-
careous sediments. Tennessee marble is of low porosity, the pore space
averaging, according to tests by the U. S. Bureau of Standards, about
0.5 per cent; it is much lower in some varieties.

The marble of this State is highly resistant to abrasion and therefore
is well-suited for use as floor tile and stair treads. Notable examples of
use are the concourses of the Grand Central and Pennsylvania Stations
in New York, where for many years Tennessee marble tile has withstood
the wear of intensive pedestrian traffic.

Manufacture and Distribution. — Many large, well-equipped mills
are in operation in and about Knoxville, where marble is manufactured
into a great variety of architectural and ornamental forms particularly
for interior use. Great quantities of marble are also shipped in rough
blocks to mills in the larger cities in all parts of the country.

Vermont.27— In 1929 Vermont produced 1,185,100 cubic feet of
building and monumental marble, valued at $4,763,471, or about 29.8 per
cent of the total value of marble produced in the United States during that
year. Production in 1930 amounted to 1,098,080 cubic feet, valued at
$4,206,456; in 1931, 905,280 cubic feet, valued at $3,187,431; and in 1937,
302,100 cubic feet, valued at $1,539,571.

General Features of Marble Belt. — ^The great marble belt of western
Vermont, which is about 80 miles long, lies chiefly between the Green
Mountains and the parallel Taconic Range to the west, a valley
ranging in width from }i mile to 4 miles. To the south, from Pine Hill
to Danby Hill, the marble lies between the Taconic Range and an

2« Dale, T. Nelson, Work cited, p. 146.

2^ The principal data on Vermont marbles were obtained from U. S. Geol. Survey
Bull. 521, The Commercial Marbles of Western Vermont, by T. Nelson Dale, supple-
mented by visits of the author to nearly all the quarries.

188 THE STONE INDUSTRIES

intermediate range and it also extends north of the Taconic Range,
ending between Middlebury and Bristol. A parallel occurrence of
marble, known as the West Rutland belt, is about 6 miles long and
3^^ mile wide. This lies west of Rutland and occupies a minor longitudinal
valley through which the Castleton River flows.

When in normal position a slaty schist overlies the marble, and a
dolomite lies beneath, but in places these relations are disturbed by
faulting. Records of drill cores and data from sections at the quarries
show that the thickness of the marble ranges from 335 to more than 850
feet. The beds were no doubt originally laid down as horizontal lime-
stone strata in the sea bottom, but in consequence of powerful crustal
contraction which operated mostly west-northwest to east-southeast the
limestones were recrystallized into marbles and at the same time intensely
folded and in places even faulted. The strike of the folds is generally
north and south, although in places it varies somewhat. During subse-
quent ages crests of folds were eroded away, leaving the marble exposed.
At a still later period cross fractures were formed through which a dense,
molten-rock magma was injected, forming trap dikes. These are 2 inches
to 25 feet wide but are not numerous.

Important Geologic Features, complexities caused by folding. —
Rocks of the great marble belt of Vermont have been intensely folded.
Most beds are steeply inchned, the only horizontal ones being sections
in the bottoms of the troughs or tops of the arches. As folds are repeated
a single bed may appear in a succession of outcrops and lateral folding
may complicate greatly the problem of tracing their course. For exam-
ple, an offset of one fourth mile in the position of certain well-defined
marble beds at West Rutland has been attributed to a sharp double
lateral fold in the form of the letter S. It will be seen that if the upper
and lower parts of the letter are continued as horizontal lines, the upper
to the right and the lower to the left, they will represent the same bed
following the same direction but will be offset from each other by the
width of the letter.

effect of pitch of folds. — The axes of folds are rarely horizontal,
but the degree of pitch is usually small — 5 to 20°. The practical effect
of the pitch is to cause variation in the distance of a bed from the surface
as a quarry is advanced along the strike. If the advance is made in the
direction of dip a desirable bed plunges deeper and deeper beneath the
surface, and in time reaches a point beyond which it can not be worked
economically. If a quarry is advanced in the opposite direction the bed
gradually comes closer to the surface until it runs out.

joint systems. — Major joints generally appear in systematic arrange-
ment. The most prominent set strikes N.65°-80°W., with a comple-
mentary set N.10°-20°E. A second system strikes N.75°-80°E., with its
complementary system N.10°-20°W. Diagonal joints occur in places.

MARBLE 189

FAULTING. — "Faulting" is a geological term applied to rock fracturing
with movement along the fractured surface, resulting in dislocation or
change in relative position of beds. The amount of dislocation is known
as the "throw" of the fault. Wherever sharp folding is found, faulting is
likely to occur. In many places in western Vermont the displacement is
only a few feet; in others it may be several hundred. When a major
fault plane is encountered in quarrying, the first step is to ascertain the
direction of throw and extent of displacement. Even a skilled geologist
may have difficulty in interpreting the structure, and core drilling may be
necessary before the continuation of the lost beds is discovered.

EFFECT OF DIKES. — Trap dikes usually occur in regions of close
jointing. Small branching dikes may invade the marble on both sides of
the larger ones. Both close jointing and lateral intrusions discourage
quarrying close to dikes. Most dikes in Vermont follow a course about
N.60°-70°E., and the next most prevalent direction is N.25°-40°E.

EFFECT OF EROSION. — Exposurc of marble beds at the surface is due
to removal of overlying schist by erosion, which at the same time carried
away much marble, leaving truncated folds. Where either an anticlinal
fold (arch) or synclinal fold (trough) has been truncated by erosion
remnants of both limbs of the fold must remain in the earth. If only
one appears in an outcrop it may be possible to locate the other by recon-
structing in theory the original structure and estimating its probable
width at the point of truncation. Such a truncated major fold is in
evidence south of West Rutland, for the beds of both the east and west
limbs have been found. Naturally beds on the east side appear in reverse
order to those on the west. Ability to picture reconstruction of the
marble folds has great practical value in facilitating search for remnants
of beds that may be concealed by glacial debris.

EFFECT OF WEATHERING. — Long ceuturics of Weathering on exposed
surfaces or on rock covered with sand or gravel generally have resulted in
alteration of marble to a depth of 15 or 20 feet, and such material must be
discarded as waste. Exceptionally, marble exposed at the surface is of
good quality, but usually some alteration has taken place unless a cover-
ing of glacial till or water-worked clay has protected it from weathering
effects. In some places the imperviousness of clay has preserved the most
delicate glacial striations, and good marble may be quarried within a few
inches of the surface.

General Succession of Beds. — Throughout many parts of the marble
belt a definite succession of workable beds may be traced. Beginning at
the overlying schist the succession as given by Dale^* is as follows: (1)
Upper graphitic marbles; (2) white graphitic and muscovite marbles
alternating; (3) upper clouded light gray marbles; (4) intermediate
dolomite; (5) lower clouded white marbles; (6) lower graphitic marbles.

28 Dale, T. Nelson, Work cited, p. 96.

190 THE STONE INDUSTRIES

The entire succession is present at few, if any, localities; certain beds are
prominent in one region, while others furnish the chief supply at another
point. At West Rutland the average thickness of all workable beds was
estimated by Dale as 783 feet and at Proctor as 616 feet. This belt
no doubt contains an extensive reserve supply of marble.

Character of Marbles. — Commercial marbles that abound throughout
the valley are of a high degree of purity; many consist of 98 to more than
99 per cent calcium carbonate. Porosity is low, and colors are attractive
for interior or exterior use. They are widely known and are used exten-
sively in all parts of the country.

Individual Quarry Districts. — Marble occurrences in the chief produc-
ing districts are briefly described in the following pages, beginning with
the most southerly quarries and advancing toward the northern end of
the belt.

DORSET MOUNTAIN. — The Imperial quarry is in the southern part of
Rutland County about 1}4 miles southwest of Danby on the northeastern
flank of Dorset Mountain and about 700 feet above the railroad. Both
open-pit and underground methods of quarrying have been employed.
The rock is a coarse-grained, faintly cream calcite marble, which is some-
what translucent. Joints are fairly regular, and large sound blocks are
obtainable. Blocks are conveyed to the railroad by means of cable cars
over an inclined railway three fourths of a mile long. The marble is used
for exterior and interior building and for memorials. The Amphitheater
in Arlington Cemetery near Washington, D. C, was built of stone from
this quarry.

The White Stone Brook quarry a short distance south of the
Imperial quarry is served by the same cable-car railway. The beds,
which total about 100 feet in thickness, dip to the east 5 to 10°. The
stone is coarse-grained and white to cream, with faint yellow to greenish
gray streaks and spots. It takes a good polish and is used for interior
and exterior building.

CLARENDON. — The Clarendon quarry is about 3 miles southeast
of West Rutland. The maximum thickness of the beds here is 327 feet.
The upper beds are graphitic marbles, the middle beds are white, lightly
mottled and banded, while the lowest is a variegated graphitic marble.
Major joints strike N.35°W. and are 3 to 7 feet apart. All the marbles
take a high polish and are well-adapted for construction. The products
are standard Vermont marbles that have been used for many years.

WEST RUTLAND, WEST SIDE. — As prcviously stated, the structure at
West Rutland is a truncated anticline, and the quarries fall into two
groups — those on the western limb and those on the eastern. Six large
quarries have been in operation on the west side; only one is now active,
although others are equipped for production. Marble occurs in a variety
of beds, aggregating nearly 200 feet in thickness. Joints are in regular

MARBLE

191

systems, and their direction and spacing are remarkably uniform, even at
depths of 100 to 150 feet. Some of the quarries are very large. Much
high-grade marble has been removed from drifts which extend along the
beds from the original open-pit workings. Very attractive green, blue,
purplish gray, and cream marbles predominate. The products are
employed chiefly for interior decoration.

WEST RUTLAND, EAST SIDE. — The eastern limb of the anticline is the
most productive region in Vermont. Beginning near the railroad station
at West Rutland an almost continuous line of about 12 quarries extends
for nearly 1 mile to the north. Those farthest to the south, including the

Fig. 31. — Starting a tunnel 400 feet beneath the surface in a West Rutland, Vt., marble
quarry. {Courtesy of Vermont Marble Company.)

Covered, New Opening, and Upper Gilson, are in an upper eastern series
of beds, and those to the north are in an adjoining western and lower
series. The quarries are all narrow openings along the strike, and they
follow the dip of the beds, which usually ranges from 35° to 45°E.,
though in places it curves at steeper or flatter angles. The Covered
quarry is the largest in Vermont; it is nearly 400 feet deep and extends
about one fourth mile underground to the south. In places the roof of
the underground workings is more than 100 feet high and is supported
by large square pillars of the original marble beds. An early stage in
projecting a new tunnel is shown in figure 31. At the Main quarries
long drifts have been projected in the direction of the strike until they
meet, which permits the use of electric mine railroads for haulage. In
the Main and in the West Blue quarries Nos. 1, 2, 3, and 4 many distinc-
tive beds are encountered, and high-grade white, bluish, greenish, and

192 THE STONE INDUSTRIES

pink architectural marbles are produced. Thousands of quarry blocks
are kept at West Rutland in a storage yard served by a 50-ton-capacity
gantry crane. Lime is manufactured as a by-product.

PROCTOR. — The beds in this locality dip about 60°E. The quarries
follow the dip downward and extend along the strike. About five large
openings have been made, but recent activity has been confined to the
Sutherland Falls quarry. Typical Proctor marble is bluish white and
translucent. Very extensive marble-finishing shops are operated at
Proctor, and slabs are brought in from various mills up and down the
valley.

PITTSFORD. — During recent years the Pittsford district has attained
increasing importance. The Pittsford Italian quarry, formerly known as
the Turner, is about three fourths mile southwest of the station at Florence
in Pittsford township and intersects the same beds as the Proctor quarries.
The most typical product is a bluish white calcite marble, mottled with
gray. Beds strike N.25°-30°W. and dip 75°E.N.E. Tunnels are
extended along the strike.

The Florentine quarry, which is about 1}^ miles west of the station at
Florence, intersects the upper graphitic beds immediately underlying the
Taconic Range schists. The beds strike N.25°W. and dip 60° to 70°W.
Structurally the beds belong to the east limb of a syncline. The charac-
teristic product is a dark bluish gray graphitic calcite marble, finely
banded with gray and uniformly fine-grained.

The Hollister quarry 1^^ miles northwest of Florence station is a very
old opening, which has been extended to a series of seven quarries known
as Pittsford Valley Nos. 1 to 7. Nos. 2 and 7 are on the well-known
Brandon Italian beds, which have been quarried for many years near
Brandon farther north. These quarries are very deep, and many lofty
chambers and drifts have been formed by removing all the marble except
that left as massive pillars for roof support. The beds strike N.5°W.
and are almost vertical, dipping 80° to nearly 90°E. The typical rock is a
light bluish gray marble, with irregular mottling due to the recurrence
of fine, gray, plicated beds. It takes a high polish, which emphasizes
the mottled effect. Generally the marbles are more bluish than those
at Proctor. In 1931 eight quarries in this district were either oper-
ating or equipped to produce. These quarries are noteworthy for the
production of unusually large, sound blocks. Masses weighing 55 to 65
tons have been quarried for the manufacture of monolithic columns.
The bowl of Scott fountain, Belle Isle, Detroit, was made from a single
block weighing 65 tons obtained from a Pittsford Valley quarry.

BRANDON. — Marble regarded as identical with that obtained in some
Pittsford Valley quarries occurs in an excavation about one half mile
south of Brandon. It is a mottled, light bluish gray rock suitable for
architectural work. A more recently developed quarry has also operated

MARBLE 193

actively in the Brandon area, producing a standard marble characteristic
of this part of the marble belt.

Other quarries have been worked north of Brandon near Middlebury,
Monkton, and Bristol, but they have not been active recently.

Economic Features of the Marble Belt. — A discussion of the western
Vermont marble belt would not be complete without brief consideration
of certain important economic factors. Available water power has been
exceptionally advantageous in developing the industry, for several large
hydroelectric plants on Otter Creek supply power to practically all the
quarries and mills. The sand resources of the marble valley have also
been utilized to provide an abrasive for sawing and surfacing the marble.

The marble beds are extremely folded, with enlargement or thinning
of certain members, and there are numerous faults. Therefore, many
uncertainties confront workers in opening new quarries and in enlarging
those now in operation. To minimize the risk of unwise development
extensive prospect drilling is constantly conducted. Cores are carefully
examined, recorded, and stored in fireproof buildings for future reference.
The great volume of information thus accumulated is of inestimable value
in interpreting geological structures, estimating reserves, and planning
future activity.

Quarry Districts Outside Western Marble Belt. — Although a large part
of the Vermont production is confined to the western belt previously
considered, there are several important quarry districts outside this area.
Four deserve mention, as each produces marble of a type quite distinct
from those already described.

swANTON. — A marble industry has been developed 1 mile southeast of
Swanton, Franklin County, near Lake Champlain in northern Vermont.
The beds are 150 feet thick. The marbles are described as quartzose
dolomites containing fine-grained magnetite. In certain beds the
magnetite has been oxidized to hematite, which makes the rock charac-
teristically reddish. Some of the beds are of uniform color; others are
mottled red and white. The products are known commercially as
"Champlain marbles," and five distinct types are marketed. On
account of the high silica content they are difficult to saw and finish.
They are highly ornamental and particularly adapted for floor tile and
stair treads, as they resist abrasion remarkably well. A finishing mill
is operated in connection with the quarry. Similar marble is obtained
farther south near St. Albans.

ISLE LA MOTTE. — A marble quarry at the south end of Isle La Motte
in Lake Champlain, Grand Isle County, was one of the earliest to be
worked in America, having been opened for lime burning in 1664 and
reopened in 1788 to furnish building stone. The deposit covers several
acres but is shallow. The rock is a fossiliferous calcite marble that has
been recrystallized, largely by chemical processes, with little compression

194 THE STONE INDUSTRIES

or distortion. Crinoid and gastropod fossil casts show their character-
istic circular structure on polished surfaces. The quarried stone is
dark gray but when polished appears almost black, with occasional white
markings. It is classed commercially with black marbles and is used
chiefly for floor tile, base, and wainscoting.

ROXBURY. — A deposit of serpentine 50 to 60 feet wide is quarried
about 1 mile south of Roxbury in Washington County, 14 miles southwest
of Montpelier. The rock was originally a basic dike, probably consisting
of peri'dotite which has altered to serpentine. Polished surfaces are
almost black but are intersected by a network of veins, some of which
consist of white magnesite and others of a mixture of magnesite and
serpentine, which gives a light green color. Stone from later openings is
a lighter green. The color contrasts are exceptionally attractive. The
product is sold as "Vermont verde antique" and is widely employed for
columns, wainscoting, and various other decoratives uses. Verde antique
is also obtained in a northward extension of the belt at Moretown.

ROCHESTER. — Serpentine marbles occur in various parts of Vermont,
and new developments are to be expected. A more recent operation
than that at Roxbury has been noted at Rochester in the extreme north-
western part of Windsor County, where an attractive verde antique is
quarried and shipped to finishing mills in rough blocks. Verde antique is
quarried also at Proctorsville, southern Windsor County.

Marble Mills. — Large mills for sawing marble blocks into slabs and
other rectangular forms are situated at West Rutland, Center Rutland,
and Florence.

Georgia. — In 1929 Georgia produced 676,190 cubic feet of building
and monumental marble, valued at $3,739,825, or about 23.4 per cent
of the total production of the United States. Separate figures are not
available for 1930. Production in 1931 was 497,370 cubic feet, valued
at $3,323,421; and in 1937, 197,340 cubic feet, valued at $1,030,407.

Pickens County: general description. — The marble industry of
Georgia is confined almost entirely to Pickens County in the north-
central part of the State, where narrow belts occur in folded strata
of Cambrian age. Certain well-defined belts have been described and
mapped by Bayley.^^ The Long Swamp Creek belt is about 3 miles
long, beginning 2 miles northeast of Jasper and terminating about 1%
miles north of the railroad station at Tate. Its width ranges from a
few feet to 125 feet; the depth is unknown. It consists of a fine-
grained, even-grained white rock of sugary texture. According to Bay-
ley's analyses, the marble is very pure, containing 97 to 99 per cent total
carbonates. Two analyses show a considerable content of magnesium.
It is folded so closely that its structure is hard to interpret.

2» Bayley, W. S., Geology of the Tate Quadrangle. Geol. Survey of Georgia
Bull. 43, 1928, pp. 75-102.

MARBLE 195

The Marble Hill belt is a hook-shaped area with its barb extending
lyi miles north of Tate post office and the stem curving around to Marble
Hill 2}^ miles to the northeast. Beyond Marble Hill the rock again
appears in two branches, one extending about 1 mile southwest of the
Amicalola quarry and the other southwest about l^i miles toward
Dawsonville. The main section of the belt, which extends from near
Tate post office to a point beyond Marble Hill post office, is about
7}^ miles long; and many quarry openings have been made in this terri-
tory, which provides the great bulk of Georgia commercial marbles.
In general, the marbles are of the high-calcium type containing 93 to
99 per cent calcium carbonate. They are very strong and of low absorp-

FiG. 32. — Diagram showing how truncation of an anticline may furnish a wide e.xposure of a
narrow bed. a, marble bed; 6, to c, marble exposure.

tion, the porosity, according to United States Bureau of Standards tests,
averaging about 0.5 per cent. Varieties recommended for exterior use
have still lower porosity. They are highly crystalline and of sugary
texture. The colors are mostly white, gray, or bluish with subsidiary
pink.

The Keithsburg belt is more extensive than the Marble Hill belt but
is unproductive. Although situated in Cherokee County, it is related
geologically to the system of belts most highly developed in Pickens
County and therefore demands brief treatment at this time. Beginning
about 2 miles southeast of Nelson it curves southwestward to about
2 miles northwest of Canton. The rock, which is exposed in many
places, is chiefly fine-grained and blue-gray, with a distinct schistosity
due to mica flakes. The marbles are too impure for commercial use.
A fourth small parallel exposure, known as the Sharp Mountain Creek
belt, extends southwestward from about 1 mile north of Ball Ground.

The most productive marble quarries of Georgia are confined to a
relatively small area near Tate and Marble Hill, in Pickens County. The

196 THE STONE INDUSTRIES

valley of Long Swamp Creek IJ^ miles east of the railway station at
Tate is nearly one half mile wide and is underlain with marble 6 to 8 feet
beneath the soil. Evidently the unusual width of the deposit is due to
truncation of an anticlinal fold, because the beds dip in opposite directions
on the east and west sides. As indicated in figure 32, the removal of
the top of such a fold by long erosion might provide a surface exposure
(a to b) three or four times as wide as the actual thickness of the belt.
The Creole and the Cherokee quarries are on the west limb of the fold,
and the Etowah is on the east limb. These quarries are described later.

The remarkable attractiveness and uniformity of the marbles in
Pickens County were recognized by early pioneers. The first systematic
quarrying was done about 1840, and in 1842 a small mill with one gang
saw was operated at Marble Hill. Nearly all the early production was
for tombstones, which were hauled many miles by mules or oxen. With
the advent of railways, markets were greatly expanded, and with an
increasing use for marble in the construction field the industry became
firmly established. The products of these great quarries and mills now
reach every section of the country and are employed for memorials, for
exterior and interior building, for numerous ornamental effects, and for
sculpture. A notable example of the last use is the heroic figure of
Abraham Lincoln carved by Daniel Chester French, and placed in that
great American shrine, the Lincoln Memorial, in Washington, D. C.
Reserve beds of marble which cover several square miles to a depth of at
least 185 feet are practically inexhaustible.

Quarries that are now or have recently been active are described
briefly in the following paragraphs. Geographically they fall in two
groups — those of the Tate district and those of the Marble Hill district.

THE TATE QUARRIES. — Near Tate are two comparatively new quarries
known as Silver Gray No. 1 and Silver Gray No. 2. The silver-
tone grayish crystalline marble from these quarries is sold prin-
cipally for monuments. Large quantities of dark blue and clouded
marbles with a white background are produced at the Creole quarry
also close to Tate. Color contrasts are sharp, and the stone is well-
suited for matched panels and other interior decorative effects. Blocks
of large size free from impurities and seams, are obtainable. The marble
works easily and takes a good polish.

The Light Cherokee quarry, situated close to Silver Gray No. 1, is
very large and deep. It furnishes several shades of light and dark
gray coarsely crystallized translucent marbles, which are suitable for both
interior and exterior use. The coloring matter is less pronounced and
more uniformly distributed than in the Creole quarry. The Mezzotint
quarry in the same group furnishes stone characterized by dark gray
wavy veining on a light gray background. It is much used in interiors
of buildings.

MARBLE 197

Marble from the Etowah quarry, within a few hundred yards of the
Creole, is an outstanding type, for while it is of characteristic coarsely
crystalline structure it is colored various delicate tints of pink (sometimes
banded with white and with darker pinks) which are attributed to
finely divided particles of hematite. It is adapted for both interior and
exterior work and is often used as a trim in contrast with white marble,
as well as for wainscoting and tiling.

THE MARBLE HILL QUARRIES. — The sccoud important group of quarries
is near Marble Hill 3 to 4 miles east and northeast of Tate. Most of
them are in a narrow, high-walled valley, through which flows the east
fork of Longswamp Creek. Many years ago one supplied marble for
stair treads and tiling for the Georgia State Capitol. Geologists claim
that the white marbles of this area have resulted from alteration of
dark marble through contact metamorphism from an intrusive mass of
hornblende. The marble is coarse-grained and translucent. Tremolite
and muscovite appear in places and make polishing difficult. The Spring
and the New York quarries, about 100 yards apart, furnish white and
clouded marbles. Stone from the Rosepia quarry, which is not readily
obtainable in large sizes, is fine-grained and therefore quite unlike the
widely used Georgia types. It is pink, with brownish clouding, and is
adapted primarily for interior use. White marble for building, interior
decoration, and monumental purposes is provided by the Kennesaw
quarry, which has been worked for many years and is very large. The
Amicolola quarry is about 1 mile south of the New York. In this district
joints are widely spaced and therefore blocks of large size are available.
Much of the product is pure white. Tremolite, which occurs in small
irregular blades, is the chief accessory mineral.

NORTHERN PICKENS COUNTY. — During reccut years marble of monu-
mental grade has been produced at Whitestone in northern Pickens
County on the Godfrey property, as described by McCallie.^" The best
marble is coarse-grained and light to dark gray. Crushed and pulverized
products are also sold.

STORAGE AND MANUFACTURE. — Much of the marble from the Tate
and Marble Hill districts is manufactured into finished products in very
extensive and well-equipped mills, most of which are operated by one
large quarrying company, and others by manufacturing firms that have
no quarries. There are marble-finishing mills at Tate, Marble Hill,
Marietta, Canton, Nelson, and Ball Ground. A feature of interest in
the quarry region is the operation of great overhead traveling cranes
that convey marble blocks to storage piles. Acres of ground are covered
with blocks waiting their turn for conveyance to mills. Railways provide
transportation between quarries, storage yards, and mills.

^ McCallie, S. W., Marbles of Georgia. Geol. Survey of Georgia Bull. 1, 1907,
pp. 49-50.

198 THE STONE INDUSTRIES

Marbles Outside Pickens County. — Marble deposits have been noted
in several counties outside the widely known Pickens County district,
but few have attained commercial importance. Recent activity has been
confined to a region about 2 miles southwest of Hollysprings in Cherokee
County, where a quarry is operated for the production of green serpentine
marble (verde antique). The rock occurs in a lenslike deposit about
600 feet long, with a maximum width of about 150 feet. Numerous
veins intersecting the massive serpentine make it highly ornamental.
They are of two kinds. A network of narrow veins, ranging from mere
hair lines to one half inch in width and filled with dark green serpentine,
is the most attractive feature of the rock. Larger and more persistent
veins up to 5 inches in width are filled with dolomite and talc; these
veins are sometimes open and cause much waste. As in most verde
antique deposits quarrymen must contend with much unsoundness, but
by cutting in accordance with joints, masses large enough for orna-
mental columns may be obtained. As waste is great and the rock can
not be cut rapidly, quarrying is expensive, but on account of its highly
ornamental character for baseboards, panels, columns, and pedestals
the marble commands a higher price than white varieties. Two types
are marketed, a rich dark green and a light green, both of which have
attractive patterns.

Missouri. — In 1929, 477,010 cubic feet of block marble was produced
in Missouri; it was valued at $927,530, or about 5.8 per cent of the value
of total production for the United States. In 1930, production fell to
395,960 cubic feet, valued at $839,616; in 1931 to 216,730 cubic feet,
valued at $553,291; and in 1937, to 180,860 cubic feet, valued at $445,114.

Carthage District. — The most important marble-producing center in
Missouri is at Carthage, Jasper County. Geologically the rock belongs
to the Burlington division of the Mississippian or Lower Carboniferous.
It is a formation of wide extent in the State and in many places is quarried
as limestone; in fact, the Carthage stone is sometimes described as lime-
stone rather than marble. Buckley and Buehler,^! in their detailed
description of the district consistently speak of the rock as limestone.
However, during the many years since this report was written the rock
has become well-established as a commercial marble.

At Carthage the marble occurs in heavy, coarsely crystalline beds.
It is white to light gray, with a bluish gray tint, although on a tooled
surface it appears almost white. It is uniform in texture and color and
has been recrystallized with little or no evidence of compression or
distortion. In one respect it resembles Tennessee marble, for it is
characterized by the presence of stylolites or suture joints parallel to the
bedding and 2 to 20 inches apart. However, some of them are less desir-

31 Buckley, E. R., and Buehler, H. A., The Quarrying Industry of Missouri.
Missouri Bur. of Geol. and Mines, vol. 2, 2d ser., 1904, pp. 121-134.

MARBLE 199

able than in Tennessee, as they are inchned to weather more rapidly than
the intervening rock. The highest quality of stone used as monument
stock contains only the very finest of them. So-called "tar seams"
containing bituminous matter cause waste in some quarries. Layers of
flint nodules occur in places. The stone takes a good polish, is very
strong, attractive, and enduring, and is used widely for both structural
and monumental purposes.

Several quarries, mostly north of the city, have been opened, but
during recent years production has been chiefly in the hands of one large
company. Some stone is sawed and finished in the district, but much
of it is shipped in rough blocks.

Phenix District. — The marble at Phenix, Greene County, is of the
same geologic age as that at Carthage and resembles the rock from that
place in many respects. It is coarsely crystalline and bluish gray and
occurs in thick beds. Where free from chert or flint nodules, large,
sound, practically flawless blocks of uniform texture may be quarried.
Fortunately, the chert nodules are confined mostly to certain zones or
layers. Suture joints or stylolites occur, as at Carthage; they are 2 to 14
inches apart and range from fine pencil-like markings to wavelike zones 3
inches in width; the larger ones are undesirable. In some beds the rock is
quite fossiliferous, and the color is a little darker than that of the Carthage
marble. A practically inexhaustible supply is available. A large mill is
operated in connection with the quarry, and both mill and quarry are
well-equipped with modern machinery. Both rough and finished stone
is produced for exterior and interior construction.

South Greerifield District. — The Logan quarry at South Greenfield,
Dade County, w^as in operation in 1929 and following years. According
to report, the stone closely resembles Carthage marble.

Joplin District. — South of Joplin, Newton County, beds of the
Mississippian formation similar to those described above are quarried
for the production of interior and exterior marble. The best bed is 9 feet
thick, coarse-grained and fossiliferous at the bottom and dense and
compact near the top. It is uniform in texture and a pleasing gray.
The suture jomts are very tight and only slightly susceptible to weather-
ing. Both rough and finished stone is marketed.

Ozora District.— Crystsdline limestone that may be classed as marble
occurs in eastern Ste. Genevieve County. Much of it is so intersected by
cutters that large, sound blocks are difficult to obtain, on which account
some operations have not been profitable. The most successful quarry
is at Ozora. The beds worked are in the Kimswick formation, which
lies geologically at a higher level than the Burlington, in which the other
marble quarries of the State are located. A very attractive fossiliferous
golden-vein marble sold in rough blocks for interior work has won a good
reputation. The walls of the elevator lobbies in the Department of

200 THE STONE INDUSTRIES

Commerce Building in Washington, D. C, are good examples of its
decorative value.

Alabama. — Building and monumental marble produced in Alabama
in 1929 was reported as amounting to 52,900 cubic feet, valued at $381,-
781, or about 2.4 per cent of the value of the total production for the
United States. Production was considerably higher in 1928. Produc-
tion in 1930 was 99,790 cubic feet, valued at $481,186; in 1931, 46,390
cubic feet valued at $201,976; and in 1937, 57,050 cubic feet, valued at
$313,663.

General Distribution. — The most important marbles of Alabama pass
through southern Talladega and northern Coosa Counties in a continuous
belt about 35 miles long, with a maximum width of 1^^ miles near
Sylacauga. They range in geologic age from Middle Cambrian to Middle
Ordovician. On the southeast the belt is bordered by the Talladega
slate or phyllite and for most of its length on the northwest by the
Knox dolomite. Prouty^^ mentions several occurrences outside this
belt which have not been worked commercially.

Characteristics of Marbles. — The marble beds are at least 200 feet thick
in their best occurrences and usually dip about 30° southeast toward the
slate. There is evidence of intense compression and folding; in conse-
quence, definite systems of j oints have been developed. A high percentage
of waste is caused by the many irregular, radial, and closely spaced joints.

Alabama marbles are mostly white, and some beds provide pure,
flawless material of statuary grade. They are a little finer-grained than
the Vermont and much finer-grained than most of the Georgia marbles.
Layers of light green talc and schist give ornamental patterns or clouding
to some varieties. Some Alabama marbles are translucent. Porosity is
low, averaging according to United States Bureau of Standards tests
about 0.5 per cent, with a somewhat lower percentage in varieties best
adapted for exterior use. The marble is notably pure, consisting of 98
to more than 99 per cent calcium carbonate. The products are widely
known and are marketed in all parts of the country.

Productive Areas. — The most productive region is at Gantts Quarry
about 2 miles southwest of Sylacauga, Talladega County, where very
large open-pit and underground openings have been made. Diagonal
jointing predominates. About 15 beds have been worked, each 4 to 11
feet thick. Because of differences in color and texture of the beds
several standard types are produced. The quarry is well-equipped with
the most modern machinery. In a completely furnished mill adjacent to
the quarry the marble is manufactured into finished products, chiefly for
use in building.

^2 Prouty, W. F., Preliminary Report on the Crystalline and Other Marbles of
Alabama. Geol. Survey of Alabama Bull. 18, 1916, pp. 41-42.

MARBLE 201

A second large quarry is about three fourths mile northeast. For
the most part, joint planes in this locality run with dip and strike, but
occasional diagonal joints result in considerable waste. Some beds are
clouded, and others are a very attractive cream white. Quarry blocks
are shipped chiefly to New York, for manufacture into finished products.

Another quarry has been opened immediately northeast of that
mentioned above. It is operated on the same beds and produces stone
of the same general quaHty. High-quality marbles have been quarried
at various other points on the belt.

Alabama marbles are used for exterior and interior building and
decoration and for monuments. Some of the waste is sold in large
fragments for use as riprap, and much of it is crushed for terrazzo, furnace
flux, or other uses or ground to a fine powder and sold as whiting
substitute.

New York. — Building and monumental marble produced in New
York in 1929 reached a volume of 51,220 cubic feet, valued at $129,202,
which represents about 0.8 per cent of the total production value for the
United States. Production in 1930 was 68,350 cubic feet, valued at
$161,214; in 1931, 22,770 cubic feet, valued at $56,059; and in 1936
9,890 cubic feet, valued at $57,774. Circumstances are somewhat
pecuhar in New York, in that more marble, in both quantity and value,
is sold rough for riprap, stucco, terrazzo, cast stone, and crushed stone
and as marble flour than as dimension stone. Present producing areas
of block marble are confined to Clinton, St. Lawrence, and Dutchess
Counties.

Clinton County. — The Chazy limestone near Plattsburg and Bluff
Point is crystalline enough to take a good polish. Much of it is quite
fossiliferous and furnishes variegated white, gray, and pink marbles suit-
able for interior use. A black marble deposit has been developed near
Plattsburg.

St. Lawrence County. — A belt of pre-Cambrian marble occurs near
Gouverneur. It is medium-textured, is mottled gray and white or solid
blue-gray and takes a lustrous polish. Much of it contains 6 to 7 per
cent magnesium and in a few places is almost pure dolomite. It is used
for both building and monumental work. The main district is about 1
mile southeast of Gouverneur, where several quarries have been operated
for many years. Much of the waste at dimension-stone quarries and the
entire production of others are used as crushed stone for ballast, road
construction, stucco, and cast stone.

Dutchess County. — The productive quarry area of Dutchess County is
about 2 miles northeast of Wingdale. At least two large openings have
been made, the rock dipping about 40° to the east in the south quarry and
50° to 60° west in the north quarry. They yield a uniform white dolomitic
marble of fine, compact texture that has been in wide demand for archi-

202 THE STONE INDUSTRIES

tectural uses. At Wingdale a large, well-equipped marble-finishing mill
is operated.

Other Quarry Districts. — Marbles have been produced at various
other places in New Yoi*k, among them the black marbles of Glens Falls,
the verde antique of Port Henry, and the white marble of Tuckahoe.
The last marble has been used quite extensively as building stone in
New York City but is now used principally for chemical purposes and the
manufacture of cast stone.

Massachusetts. — The volume of building and monumental marble
produced in Massachusetts in 1929 was 19,720 cubic feet, valued at
197,910, or a little more than 0.5 per cent of the total production value
in the United States. Production in 1936 was 9,110 cubic feet valued at
$41,353.

The true marble areas of the State are confined to Berkshire County,
where dolomitic marbles predominate. They are fine- to medium-grained
and of uniform texture and shade from white to gray. Verde antique is
quarried near Springfield, Hampden County.

Marbles of the Berkshire Hills have been quarried near Ashley Falls,
West Stockbridge, and Lee, but during recent years activity has been
confined to the last locality. Two types are produced at Lee — a clouded
and a pure white. Tremolite crystals are present in places and cause
some difficulty because they are harder than marble and on exposure
tend to weather and leave a pitted surface. The stone polishes well and
gives satisfactory service for interior and exterior construction and for
monuments. A large marble-finishing mill is operated near the quarries.

In several places on and near Russel Mountain about 4 miles from
Westfield, Hampden County, very attractive verde antique has been
quarried. Two types of material occur — a 50-foot dike of serpentine,
which is regarded as an alteration product of basic igneous rock, and a
75-foot bed of dolomitic marble impregnated with serpentine. Massive
rock from the dike is of a rich dark green, variegated by bright green
spots. A small finishing mill has been operated intermittently,

California. — In 1929 California produced 14,260 cubic feet of block
marble valued at $71,259, or less than 0.5 per cent of the total production
value for the country. In 1930, 15,740 cubic feet, valued at $50,640;
in 1931, 15,390 cubic feet, valued at $46,399; and in 1932, 10,910 cubic
feet, valued at $35,905, were reported. California marble is used almost
entirely for interior decoration. Numerous deposits have been noted in
at least 28 counties, but most of them are small or inaccessible, and in
many places the rock is too shattered to permit quarrying large, sound
blocks.

A fine-grained, hard, dolomitic marble is quarried near Lone Pine,
Inyo County. The deposit is notable for its varied colors — yellow,
black, and white, as well as white mottled with yellow, gray, and black.

MARBLE 203

Pink, yellow, and gray varieties occur at Columbia, Tuolumne County,
The belt is 150 feet wide, and sound blocks of large size are easily obtain-
able. The numerous limestone deposits of San Bernardino County are
nearly all crystalline enough to be classed as marble, but little recent
production has been noted. A quarry near Volcano, Amador County,
has been operated intermittently for many years for building and monu-
mental marble.

Onyx marbles have been reported from several localities in Cali-
fornia, but production has been small. A veinlike deposit at Suisun,
Solano County, has been designated as onyx or travertine. The onyx
deposits of California have been described by Aubury.^^

Other Marble -producing States. — About 98 per cent of the total
block marble produced in the country is obtained from the eight States
already considered. The remaining 2 per cent originates in numerous
centers that are small factors in present production, but some are interest-
ing and promise much wider development in the future. They are
described briefly by States or Territories in alphabetical order.

Alaska. — Numerous marble deposits in southeastern Alaska have been
described by Burchard.^^ While several companies have operated in
various places production has been confined chiefly to Tokeen on Marble
Island and Calder on Prince of Wales Island. The Calder quarry is on a
bluff about 100 feet above sea level. Metamorphism of the original
limestone probably was caused by an intrusive granite which lies north-
east of the marble. The belt is approximately 3,000 feet wide and at
least 200 feet deep. Three types of marble are quarried — a pure white,
which is the most valuable, a blue-veined white, and a light blue or
mottled variety. The white marble is very pure, as analyses show more
than 99 per cent calcium carbonate. Blocks are conveyed over an
inclined railway to a wharf on deep water at Marble Cove.

At Tokeen a deposit about 2,500 feet wide and not far above water
level includes white, blue-black, and various shades of gray marbles.
They are medium- to fine-grained, take a good polish, and resemble some
Italian varieties. Matched slabs having dark veins on a white back-
ground are much in demand for interior decoration. A high percentage
of waste is occasioned by close and irregular joints.

All Alaska marbles are shipped by freight steamers to finishing mills
on the Pacific coast, the largest being at Tacoma, Wash. To save freight
only perfect blocks are shipped. Finished products are marketed chiefly
throughout the Pacific Coast States.

'' Aubury, Lewis E., The Structural and Industrial Materials of California.
California State Min. Bur. Bull. 38, 1906, pp. 111-114.

3* Burchard, E. F., Marble Resources of Southeastern Alaska. U. S. Geol.
Survey Bull. 682, 1920, p. 118.

204 THE STONE INDUSTRIES

Arizona. — Onyx marbles are the only types produced in Arizona.
The most extensively developed deposit consisting of bedded calcite and
aragonite beautifully colored by iron oxides is at Mayer, Yavapai
County, 15 miles southeast of Prescott. Highly ornamental products
are obtainable from blocks having combined shades of white, green, and
red. The deposit ranges in thickness from a few inches to 25 feet and
covers an area of about 1 square mile. A finishing plant is at Dyersville,
Iowa.

A second deposit is on Camp Creek west of Cave Creek, Maricopa
County, about 52 miles north of Phoenix. It consists of boulders of
calcite and aragonite in soft travertine. After conveyance to a mill at
Phoenix the boulders are cemented together in a solid mass with plaster
of paris and sawed into slabs and blocks for polishing.

Arkansas. — The best-known marbles of Arkansas occur northeast of
Batesville, Independence County. The rock is classed by geologists as
limestone, but it is recrystallized enough to take a good polish and is
therefore classed commercially as marble. It consists of almost pure
calcium carbonate occurring in the Boone chert series of lower Carbonifer-
ous Age. The rock is gray, of oolitic texture, and although more crystal-
line, resembles Bedford limestone. It occurs in beds 3 to 5 feet thick
and being comparatively free from flaws or seams may be obtained in
large, sound blocks suitable for exterior building. It has been used to a
limited extent as monumental stone.

Black marbles of very good quality, occurring in the Fayetteville and
Pitkin formations of Mississippian age, outcrop on the north slope of the
Boston Mountain escarpment. Several quarries have been opened near
Marshall and at other points west of Batesville, and the product is
marketed as "Arkansas Black."

In 1929 a deposit in the Kims wick and Ferndale formations of Ordo-
vician age was developed near Guion, Izard County, about 20 miles north-
west of Batesville. The marble is coarsely crystallized and of a prevailing
light gray; it occurs in approximately horizontal beds. Fair success has
been attained in quarrying it with a wire saw.

A small amount of marble is produced at times near Cartney, Baxter
County.

Colorado. — Marble has been quarried quite extensively on Yule
Creek near Marble in northern Gunnison County, at a point about
10,000 feet above sea level and about 2,000 feet higher than the Crystal
River Railroad. It occurs in massive beds at least 100 feet thick, with
widely spaced joints which permit very large, sound blocks to be quarried.
Pure white marbles almost of statuary grade are obtainable, as well as
faintly clouded and golden-vein types that afford very attractive archi-
tectural effects. A large, well-equipped mill is operated at Marble.
The industry is handicapped somewhat by difficult, costly transportation.

MARBLE 205

The Lincoln Memorial in Washington, D. C, is built mainly of marble
from this quarry. The superstructure of the Tomb of the Unknown
Soldier at Arlington also is of Colorado marble.

Maryland. — Although marbles occur in many localities in Maryland
they have been actively quarried in only two districts during recent years.
White marbles are quarried at Cockeysville, Baltimore County, and
verde antique at Cardiff, Harford County. Years ago a highly orna-
mental conglomerate known as "Potomac marble" was quarried near
Point of Rocks, Frederick County, but there has been no recent
production.

The Cockeysville deposit about 15 miles north of Baltimore is of
Ordovician age and consists of fine-grained, white, dolomitic marble of
uniform texture. Pyrite crystals are quite common, but they are unu-
sually stable, as evidenced by marble structures containing pyrite being
exposed to the weather for over 100 years with no evidence of staining.
Polished Cockeysville marble is of a dazzling whiteness quite noticeable
in structures in many parts of Baltimore. Many monolithic columns
have been manufactured for large buildings. The cheaper grades of this
marble have been sold extensively for residential door steps, a characteris-
tic feature of many houses in Baltimore. The stone has a good reputation
and has been widely used for many years. A well-equipped finishing
mill is operated in connection with the quarry.

A large serpentine area extends from the Susquehanna River near the
Maryland-Pennsylvania boundary southwestward through Harford
County into Baltimore County. Quarries have been worked in various
places, but present production is confined to one large quarry at Cardiff.
The rock is a very attractive, dark green, veined serpentine — a typical
verde antique. Formerly the chief products were granules, terrazzo,
stucco, and sand ; and while these are still important, the principal output
since 1920 is block marble, which is in demand by architects and
builders. During recent years the operation has become increasingly
extensive. The directions of the quarry walls have been altered in the
lower part of the quarry to conform to the major joints, and waste has
been reduced thereby. On account of a heavy overburden of defective
rock underground drifting methods are pursued. Unsound blocks are
manufactured into floor tile and baseboard in a mill at the quarry, and
large, sound blocks are shipped to New York and other cities.

Michigan. — An attractive verde antique was quarried some years
ago in a small way in Marquette County.

Montana. — Marble for interior building purposes, described as jet-
black with a delicate gold vein, has been quarried near Townsend, Broad-
water County. It is shipped in rough blocks. A vein of onyx
marble 65 feet wide in Gallatin County, about 5 miles north of Manhat-
tan, has been worked in a small way since 1930. A silicified, banded,

206 THE STONE INDUSTRIES

ornamental rock known as "Montana onyx" occurs near Virginia City,
Madison County.

New Jersey. — A light green verde antique of attractive veining has
been quarried about 2 miles from Phillipsburg, Warren County.
Although the chief product is terrazzo, wider use of the stone in block
form is in prospect.

North Carolina. — Commercial marble developments of North Carolina
have been confined almost entirely to Cherokee County. The marble
bed, extending across the county in a belt 1,000 feet to about a half mile
wide, is a northward extension of the beds of Fannin County, Ga. It
strikes northeast and dips about 50° southeast. The largest early opera-
tions were near Murphy and Regal, but recent production has been from
a quarry near Marble. Two types of marble are obtained — a dark bluish
gray, some of which is streaked and mottled with white, and a more or less
uniform white stone. Close, irregular jointing at various intersecting
angles has discouraged quarrying in this region, but the joints are more
regular and more widely spaced near Marble than in other parts of the
belt. A large marble-finishing plant has recently been built.

Pennsylvania. — A deposit of white marble in York County has
been worked to a limited extent for local use. White marble was also
quarried quite extensively in past years at King of Prussia, Montgomery
County. Yellowish green serpentine from Chester County has been
used for facing buildings, chiefly in and about Philadelphia and also in
Washington, D. C. This stone weathers too rapidly for satisfactory
exterior use and therefore has not been quarried for many years.

Puerto Rico. — A large, undeveloped deposit of gray marble with
attractive dendritic markings consisting chiefly of manganese oxide occurs
at the surface in the southern part of Puerto Rico. It takes a good
polish and is available in large blocks.

Texas. — There is a deposit of attractive black marble near Marfa,
Brewster County, which was developed to some extent in 1929.

Utah. — An interior building marble is produced in small quantity at
Thistle, Utah County. On account of its unusual markings one
variety is called "birdseye."

Virginia. — A black marble of good quality is quarried near Harrison-
burg, Rockingham County. During recent years it has been used prin-
cipally for terrazzo, but a mill for producing slabs was erected in 1933.

Washington. — Multicolored marble chips for terrazzo floors are pro-
duced in Stevens County.

QUARRY METHODS AND EQUIPMENT

Prospecting. — Marble is a recrystallized — that is, a metamorphosed —
limestone. Metamorphism that converts limestone into marble is usu-
ally brought about by intense pressure and folding. Thus, the direction

MARBLE 207

and thickness of any bed may change abruptly, either laterally or verti-
cally. On this account, marble beds are more uncertain in position and
extent than flat-lying sandstones or limestones, and careful prospecting
is essential to successful marble quarrying. It is extremely unwise to
proceed with development work or with the extension of openings without
reasonable assurance that an available mass of sound, attractive marble is
sufficiently uniform in quality and abundant in supply for profitable
exploitation.

Most marble beds outcrop in long, narrow bands which may extend
many miles and represent truncated edges of folds in the rock; they may
be curved or straight, depending upon the topography and the nature
of the fold. A geologist may, by careful study of outcrops exposed here
and there, obtain a knowledge of the chief structural features and thus
determine the position, thickness, and attitude of beds with fair accuracy.
Geologic maps of marble belts, if carefully made, have inestimable value
to a prospector, for by consulting them he may determine the position
of marble belts beneath the surface and know something of their extent
and attitude.

Knowledge of exposed beds and their continuation beneath the sur-
face is, however, insufficient. The nature and quality of the rock and
extent of reserves can be determined definitely only by drilling. So much
depends upon color, texture, uniformity, and general appearance that
core drilling is necessary, for only by such means can solid samples be
obtained at depth. As a rule, marble can be worked profitably only on a
large scale, and a considerable outlay to determine whether conditions
are favorable is regarded as a justifiable expense. Therefore, the larger
marble companies do very extensive core drilling. The general prin-
ciples of core drilling have been described in chapter IV, and the subject
is presented at this time merely to emphasize its importance in view of
the uncertain and variable character of most marble deposits.

Economic Conditions. — The success of a marble enterprise depends
upon several important considerations quite distinct from the quality
and extent of a deposit. A wise prospective marble producer gives
careful consideration to market demands, prices, transportation facilities,
competitive conditions, availability of labor, wage scale, and other eco-
nomic questions for which a reasonably satisfactory answer should be
obtained before large expenditures are made. Many enterprises have
failed because these matters have not been fully studied.

Quarry Plan. — The chief factors which influence the plan of quarry
operation are dip of the beds, depth of overburden, and uniformity of the
product in the beds; these factors are intimately related. If desirable
beds are thin and dip at steep angles, shallow quarries are worked along
the outcrop, or underground mining is employed. However, thick beds
dipping at steep angles may be worked in deep open pits, as at Knoxville,

208

THE STONE INDUSTRIES

Tenn. If the strata are flat and the desirable bed is near the surface, a
wide, shallow quarry results.

As regards flat-lying uniform beds of great thickness, a heavy over-
burden tends to promote deep quarrying, whereas a light overburden
will encourage the development of wider, shallower pits. If beds are
vertical or steeply inclined a heavy overburden makes deep quarrying or
tunneling almost obligatory, whereas if only light stripping is necessary
greater lateral development is possible in the direction of the strike.

Fig. 33. — Method of channeling marble in Georgia. {Courteny of Georgia Marble Company.)

Quarry plans may be influenced greatly by the quality of the deposit.
For example, if the marble commands a high price, removal of a heavy
overburden over an extended area may be fully justified, or underground
methods might be employed. For a low-priced marble neither plan
might be economically possible.

Channeling. — After a rock surface is cleared of all loose material by
any of the stripping methods described in chapter IV the next step is to
make primary cuts by means of which blocks are separated from solid
beds. As the integrity of blocks must be preserved explosives are used
sparingly. If the upper level of the rock is inferior through ages of
weathering its removal as waste may be expedited by careful use of
explosives; but where sound and serviceable rock is worked, very little,
if any, explosive is employed.

MARBLE 209

Primary cuts are made almost universally with channeling machines,
the general principles of which have been describe^ in the chapter on
limestone. Both steam and compressed-air machines are used in marble
quarrying. The channeling process is illustrated in figure 33.

Sullivan, Ingersoll-Rand, Wardwell, Tysaman, and several other types
of channeling machines are used, and each has its advocates. A favorite
machine is the double-swivel channeler, which can be used for straight
vertical cuts, for undercutting, or for cutting out corners. A few quarries
in which operations are scattered over a wide area, and in which elec-
tricity is not used, employ machines with portable boilers attached.
The "duplex" channeler consists of two machines on a single truck work-
ing in the same channel.

The electric-air channeler is self-contained, as all the mechanism is
on the channeler truck. The air, compressed by a motor-driven "pul-
sator," is never exhausted into the open but simply driven back and
forth under pressure in a closed circuit. The machine may be used for
vertical, inclined, or horizontal channeling.

The chief factors to be considered in channeling are dip of the beds,
soundness, and rift of the deposit. Where the rock is uniform, with no
open bedding planes and no decided rift, channeling may be conducted
on a level floor, a most desirable condition. However, if the beds are
inclined it may be necessary to quarry each bed separately to maintain
uniformity. The removal of right-angled blocks from successive dipping
beds results in an uneven or saw tooth floor, which necessitates con-
struction of an elevated track for the channeling machine. An improved
method of quarrying on dipping beds is to place the channeling-machine
track on the inclined rock surface in the direction of the dip. A balance
weight overcomes the force of gravity which tends to pull the machine
downhill.

The tendency of joints to occur in parallel systems has been pointed
out. The importance of recognizing such systems and quarrying in
accordance with them can scarcely be overestimated. A practical
quarryman realizes that the prime object in marble quarrying is not to
establish high records in rate of channeling or in gross production per man
per month, irrespective of form or quality of the product, but rather to
produce sound blocks of uniform quality. Cuts are, therefore, usually
made perpendicular to or more rarely parallel to joints, and spaced to
reduce to a minimum the number of joints in blocks. In many deposits
one system is prominent, and cross joints are few. Under such con-
ditions it is wise to channel in one direction only — at right angles to the
chief system. Advantage may thus be taken of joints in making cross
breaks. If joint systems permit, cuts are made at right angles to the
direction of rift to take advantage gf the direction of easy splitting in
making cross breaks by drilling and wedging.

210 THE STONE INDUSTRIES

The rate of channeling varies greatly, depending on the hardness of
the marble and convenience of operation. Where the machine works on
an elevated track the daily average is low because so much time is lost
in moving tracks. Recorded average rates range from 25 to 80 square
feet a day for one machine.

Use of Wire Saws in Marble Quarries. — The construction and
operation of wire saws are described in detail in a later chapter on slate.
This method of cutting rather than channeling is followed in many
European marble quarries but has been used to a very limited extent in
cutting American marbles. Wire saws were employed about 1914, with
favorable results, in a large quarry at Marble, Colo., and WeigeF^ has
described their successful use in an Arkansas quarry during 1929.
Companies in Vermont and Tennessee have tried them, with rather
discouraging consequences. They are, however, used in trimming blocks
in quarry yards as described later. There seems to be no valid reason why
this equipment should not prove as successful in quarries as in yards, or
should be less advantageous in American quarries than in those of Europe.
No doubt problems that now confront American operators will be solved
and wire saws will in time be recognized as standard equipment in
quarrying marble as they are already recognized in the quarrying of slate.

Drilling. — A certain amount of channeling is regarded as necessary in
most marble quarries. However, rock masses are separated by drilling
and wedging wherever possible because they are ordinarily much less
expensive than channeling. Drilling and wedging are almost invariably
used for floor cuts.

The tripod, bar drill or quarry bar, gadder, and hammer drill are the
chief types of drills employed. As the name implies, a tripod is a drill
mounted on three iron legs. Its use is confined almost entirely to vertical
holes, and it must be moved to a new position for each hole. The
quarry bar has been described in the chapter on granite. It is used
chiefly for vertical drilling, but a bar of adjustable height may also be
used for projecting holes in horizontal rows in a bench face. A gadder
is a bar held in vertical or inclined position, to which a drill is attached
for making horizontal holes in the face, either in vertical or inclined
rows. Two gadders are shown at the right in figure 36, page 215. The
hammer drill, which has been described, has replaced to a great extent
heavier types of drills in many marble quarries.

Drilling usually follows the direction of the rift or grain of the marble,
thus taking advantage of the ease of splitting. The spacing of holes
ranges from 4 inches to 2 feet, depending on the rift. Drill holes should
be as small as possible without detracting from wedging efficiency;
most hammer-drill holes are 1}^ to 1^^ inches in diameter at the top.

^^See bibliography at the end of this chapter.

MARBLE 211

If the rock is uniform and sound, lines of drill holes may be spaced
regularly to give uniform, rectangular blocks. If unsound or lacking
in uniformity of color or texture, adjustment of the spacing or
direction of the lines of holes may be necessary to avoid waste and to
grade the product properly. Making alternate holes shallow and
intervening holes the full depth of the break desired is common practice.
The depth of each hole is marked on the surface of the rock to guide
workers in selecting wedges.

Wedging. — Wherever possible blocks should be separated by wedging,
particularly where breaks are made to parallel the rift. To obtain a
straight, uniform fracture proper wedges should be used, and they should
be carefully driven . * ' Plug-and-f eather ' ' wedges, as previously described
are universally employed.

A type of wedge that has proved highly successful is one of which the
feathers are 3 feet long and the plug 3 feet 9 inches; the additional 9
inches is required for driving. The feathers are curved on one surface to
fit the drill hole ; the flat surface is perfectly straight and gives a uniform
taper from one end to the other. The important feature is that, with
the wedge in any position, the total diameter of feathers and wedge is
the same at all points. Consequently, when the plug and feathers are
inserted into the drill hole the inner side of each feather is in contact with
the plug and the outer side with the wall of the drill hole throughout its
entire length. Therefore, when the plug is driven the feathers are forced
apart a uniform distance at every point. As a result the pressure
exerted is distributed uniformly over their full length. Straight, even
fractures are thus obtained with much lighter sledging than by any
other method yet devised. In driving wedges it is important that the
strain on all of them should be equal. A more uniform break will result
by giving the rock sufficient time to fracture gradually, therefore wedging
should never be unduly hastened, especially in marble that has no rift.

A pronounced rift is exceptionally advantageous in wedging, for it
may allow comparatively wide spacing of holes and permit extending
floor breaks to double the width of the ordinary marble block. Thus,
a great saving is accomplished, for channel cuts may be made at intervals
of 10 or 12 rather than 5 or 6 feet, and intermediate breaks may be made
by drilling and wedging, which is a less costly method than channeling.

Usually rift parallels bedding; therefore, if the bedding dips at a
steep angle, the rift may be inclined in like manner. If the rift is inclined
and the quarry floor level, the direction in which drill holes are projected
for floor breaks is exceedingly important. In a Colorado quarry where
the floor is level and rift steeply inclined, channel cuts are made parallel
to the strike of the rock. The influence of rift on the process of wedging
under such conditions is shown in figure 34. When the row of key blocks
has been removed and holes are drilled in the direction shown by arrow a

212

THE STONE INDUSTRIES

in the figure, the break made by wedging tends to leave the plane of the
drill holes and slant upward on the rift, thus removing a corner of the
block, as at x. When holes are drilled in the opposite direction, shown
by the arrow 6, if the channel cut is not continued lower than the plane
of the drill holes, the break will be straight, as it will not run down below
the bottom of the channel cut. It is apparent that, to avoid waste by
broken corners and to reduce expense in drilling, the row of key block,s
should be taken out as near as possible to the left side of the quarry, as
shown in the figure, so that most of the drilling may be done in direction b.
Loosening Key Blocks. — In opening up a new floor the first blocks
to be removed are known as "key blocks." Their removal is difficult
because no face is available from which to work. If a band or mass of

Fig. 34. — Diagram showing influence of rift on bottom breaks.

inferior rock traverses a quarry, key blocks may be located therein and
removed readily by blasting into fragments but if key blocks consist of
good marble they are usually preserved. After channels are cut on four
sides the most difficult step is to make a floor break for the first block. A
common method is to insert a slanting iron plate in the bottom of the
channel cut and place the point of a wedge between it and the key block.
When the wedge is driven the entire strain is exerted at the bottom of the
block. A series of such wedges may be placed close together and sledged
in succession. A horizontal rift greatly assists the process. After the
first block has been removed, horizontal bottom holes may be drilled and
the next block broken free by wedging.

Hoisting Out Key Blocks. — Any one of three methods may be used
for hoisting out the first key block. The first is by use of the Lewis pin,
which is adapted only to strong rock. A hole several inches deep is
drilled at the center of the upper surface, and a bar with an eye in the top
is placed in the hole with a wedge at each side of it. The bar is thicker
at the bottom than at the top, so that when pulled upward it tends to
tighten on the wedges, and the block may be lifted out with a derrick
hoist. A second method, which may also be employed in strong rock is
the use of grab hooks. Small pieces may have to be broken from the
corners of adjoining blocks to make room for the hooks. If beds are weak

MARBLE

213

a third method is employed. Chain loops or cables are thrown over the
block from opposite sides and drawn tight.

Subsequent Floor Breaks. — Removal of a row of key blocks provides
a working face from which floor and vertical breaks may be made for
subsequent removal of blocks. Floor breaks are usually made by drilling
and wedging, though horizontal channel cuts may be made under certain
conditions — for example, in driving tunnel headings. Where quarrying
is conducted on a steeply slanting floor the wedging method would incur
the danger of blocks sliding down upon the men the moment they were
broken loose. To overcome this a single hole is drilled at the center
of the floor line, and a light powder charge is exploded in it. The charge
is so small that it makes the floor break without otherwise shattering
the block.

Roof Line Drill Ho/es-y > / / / ' / / /
Tunnel Channel Cuh_

.Channel Cuh

WTTT/TTTT.

Floor Line
Drill Holes-
' / / A

/// /

y/,

/// // // / / / ' / / / / / ///

' / e ' / / /

////

^ ///

Fig. 35. — Diagram illustrating method of driving a tunnel in marble.

Underground Operations. — To follow steeply inclined beds without
the heavy expense of excessive stripping may demand underground
mining. Extracting marble blocks from drifts and tunnels is not uncom-
mon; very extensive underground operations are conducted, particularly
in Vermont. In underground work the most difficult step is to drive
the preliminary opening at the roof. If the drift cuts across the beds
open joints or seams are rarely available, and the heading must be driven
in the solid rock without any assistance from rock structures. A com-
mon method of advancing a tunnel or drift is shown in figure 35. First
a channel cut about 7 feet deep is made, beginning about 3 feet above the
floor and slanting downward to meet the floor line. A row of horizontal
holes is then drilled at the floor and another at the roof, the heading being

6 or 7 feet high. Horizontal holes are also drilled in vertical rows about

7 feet apart. The lower wedge-shaped mass of rock x in the figure is dis-
lodged by blasting in the drill holes below the channel cut. Light charges
of black blasting powder are used so that the marble beneath is not
shattered. The upper overhanging ledge y is then broken down by dis-
charging blasts in the holes above the channel cut. Broken rock is
removed and the process repeated. If the heading is driven parallel

214 THE STONE INDUSTRIES

with the bedding an open seam may be utiHzed for roof or floor. A bed
of soft schist or talc sometimes serves as a cushion to preserve underlying
rock from the effects of blasting.

If a tunnel is driven in beds of high-grade marble the process may be
modified to preserve the blocks. To provide space for removal of key
blocks channel cuts must be made. Horizontal floor cuts may be made
with a channeling machine, a slow process. Vertical cuts may be made
with a reciprocating drill mounted on a rotating head. While operating
it is rotated back and forth through a vertical arc, and thus it cuts a
channel in much the same way as the circle-cutting drill described in the
chapter on sandstone.

When a preliminary heading of sufficient width and length is obtained
channeling machines or drills may be set up on the floor, and operation
proceeds like that in an open quarry. As underground workings are
enlarged pillars of marble 15 to 20 feet square are left for support at
50- to 80-foot intervals, depending upon the strength and stability of
the roof.

In underground work certain complications are encountered which
do not concern open-pit quarrymen. Artificial lighting and ventilation
must be provided, and lateral haulage to open shafts becomes increasingly
difficult. In some extensive workings in Vermont trackage is provided
for hauling blocks through tunnels to hoist derricks at open quarries.
Cable cars or electric trolleys may be used.

Undercutting. — The tunnel method may be modified by enlarging the
quarry floor by an outward inclination of wall cuts. The process is
simple, requiring no additional equipment and no expensive preliminary
operation. A wide floor space is obtained with a minimum of stripping,
and with moderate extension no supporting pillars are present to obstruct
quarry operations. There are, however, certain disadvantages. In
tunneling, the projection of a preliminary opening is costly and may pro-
duce only waste rock, but when once completed the subsequent channel-
ing and drilling are carried on with almost the same facility as in an
open quarry. In undercutting, however, every wall cut is slanting, and
channeling at an angle is slow and relatively expensive. Moreover
blocks of the outer row are angular, resulting in waste.

In extensive undercutting the danger from overhanging rock may be
averted by leaving wing supports of marble at intervals. Undercutting
is employed successfully in many Georgia and Vermont marble quarries.
It is illustrated at the right in figure 36.

Hoisting. — As a step preparatory to hoisting, blocks usually are turned
down by a gang of men with crowbars. The hoist cable may be attached
by grab hooks, chains, or cable slings. Grab hooks are employed only
when rock is hard and coherent. Two holes for the hooks are made on
opposite sides of a block a few inches from the top. The mistake is some-

MARBLE

215

times made of drilling grab hook holes too deep, for the chief strain then
comes not at the tips of the hooks but on the curved parts that are in
contact with the upper edge of the block. Consequently, a corner of
a block may chip off and allow the whole mass to fall. Holes should be
deep enough to allow a firm grip of the rock, but the chief pressure should
fall on the tip of the hook in the bottom of the hole. Also, the rock
should be carefully balanced, as partial rotation may cause the hooks
to slip. A safer method of attachment is to pass a chain completely

Fig. 36.

-A marble quarry showing simultaneous hoisting, channeling and gadding
operations. {Courtesy of Georgia Marble Company.)

around the block, as shown in figure 36. Another method of attachment
is by means of a pair of cable slings, which are quickly handled and per-
mit easy balancing.

Hoisting usually is done by powerful derricks. Masts and booms may
be of wood or steel. Spliced wooden derricks having mast and boom,
each in four pieces, are used in some regions. They are easy to transport
and set up. Many derricks have a lifting capacity of 15 to 18 tons, but
some are much larger. Derrick guys usually are supported by angle-steel
bars set in concrete. The size of a derrick and choice of its location
are governed by the position and inclination of beds and by the plan of
development. Steam, compressed-air, or electric hoists may be used.
Blocks are hoisted from the quarry and loaded on cars in one operation, if

216 THE STONE INDUSTRIES

possible; if a second step is necessary they are placed in a convenient
position for future loading.

Scabbling. — The term "scabbling," as used by quarrymen, denotes
the trimming of blocks to true rectangular form. Where a mill is close
to a quarry this process may be omitted. If situated at a distance, or
if the marble is to be sold in crude form, blocks are scabbled to avoid
carrying waste material. The most common method is by manual labor
with a scabbling pick. Hammer drills and wedges are used occasionally
to remove the more prominent surface irregularities. In Tennessee a
bar drill, mounted on a triangular plank frame resting on the surface
of the block, is used to advantage. Drill holes are sunk in a row, and
their position is guided by the inner edge of the plank base. By driving
wedges in such drill holes an irregular surface is easily slabbed off. Wire
saws are used successfully at some quarries. A number of blocks may be
lined up and trimmed simultaneously with a single wire. Some operators
regard this as the most economical method.

TRANSPORTATION

In some quarry regions mills are situated so favorably that short
hauls only are required. In several eastern localities blocks are loaded
by quarry derricks directly upon transfer cars. For distant haulage
railroad cars and locomotives, electric trolley lines, and tractors are
utilized. Cable cars may be required on steep grades. Teams and
wagons were frequently used in past years, but the present tendency to
consolidate companies into large units and the necessity for greater speed
have led to more general use of rail transport.

EQUIPMENT AND OPERATION IN MILLS AND SHOPS

Most marble quarries of the United States have plants equipped more
or less completely for sawing, polishing, carving, or otherwise preparing
marble for structural and memorial uses. Also in many large cities mills
are operated by independent companies.

Mill Location and Construction. — Mills operated by quarry com-
panies may be close to quarries or in some near-by town. Water supply,
power, and labor conditions are the chief factors that govern location.
Laborers usually are better satisfied if mills are near towns where schools
and other public institutions are more convenient and better equipped
than in comparatively unsettled regions.

The most modern mills are fireproof, and many that are not have
sprinkler systems. In most northern mills hot-air- or steam-heating
systems are used.

Power. — Water, steam, and electricity are sources of power; the last
is the most widely employed. Some large companies develop their own
electric power, while others purchase it from power lines. One motor

MARBLE

217

may provide power for the entire mill, but it is usually advantageous to
employ smaller units. For transmission from fly-wheel to countershaft
pulley two types of belts are employed, a broad one of leather or fabric
and a rope belt. The latter has the advantages of low first cost and of
easy tightening, the pulley designed for this purpose being applied to a
single turn of the rope. Direct water power is commonly transmitted
by gears.

Traveling.^..
Crane

Shop

Traveling
'■Crane

Sl-ock Pile

Shop

-<bang
Saws

Fig. 37. — Convenient track arrangement for a marble mill.

Arrangement of Mill, Shop, and Yard. — The mill is that part of the
finishing plant where gang sawing is done ; all other finishing is classed as
shop work. Stone is a heavy product, consequently the mill, shop, and
yard usually are arranged to permit minimum handling.

Where both sawing and shop work are conducted the mill and shop are
often placed 30 to 60 feet apart, with an overhead traveling crane between.
A convenient arrangement for a large finishing mill is shown in figure 37.
One traveling crane unloads blocks from cars on their arrival at the mill
and either piles them or loads them on transfer cars. A track passes
down the center with gangs on either side, and a small locomotive

218

THE STONE INDUSTRIES

crane spots transfer cars. Beyond the mill is the shop, and at the end
of it another smaller traveling crane loads finished stock on railroad cars.
Sawing. — A first and very important step in milling is sawing the
marble into slabs or rectangular blocks. The gang saws universally
used are similar in construction and operation to those employed in
sandstone and limestone mills, as described in preceding chapters.
Silica sand is the abrasive used most commonly, though in some mills
steel shot are employed, and greater speed in sawing is attained thereby.

'Xa gl: '11

_ -..a^;* ill

Fig. 38. — Gang saw in operation in a marble mill. (Courtesy of Vermont Marble Company.)

Shot are rarely used on marbles that are porous or contain soft veins, as steel
particles may lodge and cause rusty stains or may interfere with later
finishing processes. Slabs usually are sawed parallel to the grain,
though sometimes distinctive markings are obtained by sawing crosswise.
Great saving of material may be effected by sawing parallel with any
joints that may be present in blocks. However, if cuts must parallel
the grain it may be impossible to saw in accordance with the unsoundness.
As a rule, unsound blocks can be sawed to better advantage into cubic
stock than into thin slabs. The rate of sawing varies greatly, depending
on the hardness of the marble. In stone of moderate hardness, the blades
may sink at a rate of 1 to 2 inches an hour; in extremely hard marbles they
may advance not more than 3 or 4 inches during an entire shift. Gang-
saw operation is illustrated in figure 38.

MARBLE 219

Gang-car and transfer-car systems employed in marble mills are similar
to those used in sandstone mills. Some large mills have more than 40
sawing machines and are equipped with every modern contrivance for
handling materials. Sawed blocks and slabs are removed from cars by
overhead cranes or derricks. Cubic stock may be handled with grab
hooks or smooth-faced iron clamps which automatically close upon a
block when under tension. Thin slabs may be removed in the same way
or by cable slings.

Wire saws are used to a limited extent in place of gang saws. Several
blocks may be lined up and sawed simultaneously. The operation
requires little power or attention and gives satisfactory results in uniform
material if slight variation in the thickness of slabs may be allowed.

Shop or Finishing Plant. — All finishing of marble after sawing is
conducted in the shop. Where shops are operated in conjunction with
mills they are usually so situated that sawed material can be transferred
to them with the greatest facility. The shop may be a continuation of
the mill, or the two buildings may be in parallel positions with a traveling
crane between. Various shop operations are described in following
paragraphs.

Coping and Jointing. — "Coping" and "jointing" are terms appHed
to the subdivision of marble slabs into baseboards, tile, or other finished
products by means of Carborundum wheels or saws. In its strict sense
coping is the process of cutting one slab into two without regard to the
finish of edges. In jointing, however, the edges must be true and
square with the face and without chipped corners. Carborundum wheels
generally are employed for jointing because they usually leave so smooth
a surface that edge rubbing is unnecessary. For this operation the wheel
should project through the slab into a groove in the steel bed.

Rubbing. — Slabs and blocks cut to approximate size are squared and
finished on a "rubbing bed," consisting of a horizontal circular bed of
cast iron revolving at moderate speed. Most beds are driven from above
by countershaft and gears, but some are geared underneath. Marble
slabs or blocks held on the surface of the revolving disk to which sand and
water are supplied are worn down to desired dimensions and smoothness.
Carborundum beds are used to some extent for rubbing small pieces.
Curved and irregular surfaces require hand rubbing with Carborundum
bricks or with small pieces of marble supplied with sand and water.

Gritting and Buffing. — Gritting is a process which gives a smoother
surface than rubbing. Emery powder is sometimes used as abrasive for
this purpose. More frequently abrasive bricks are attached to revolving
buffer heads which travel over the surface. The bricks are of silicon
carbide or aluminum oxide, of varying degrees of fineness, depending upon
the finish desired. Gritting produces what is known to the trade as a
"hone" finish. For hand-gritting curved or irregular surfaces, natural

220

THE STONE INDUSTRIES

hone or pumice is used, though artificial abrasives are displacing them
rapidly.

Buffing, the process which gives the final polish to marble, is accom-
plished by guiding over the wetted surface a buffer head of felt or other
material of soft texture. "Putty powder," consisting of tin oxide or a
mixture of tin oxide and oxalic acid, is used as abrasive. Chromium
oxide — a green powder — is also used. Figure 39 shows a buffer or
"Jenny Lind," as it is called in England. Various abrasive heads are

Fig. 39. — A buffer used for gritting and polishing marble surfaces.

Marble Company.)

{Courtesy of Vermont

shown in the foreground. Irregular surfaces are polished by hand with
putty powder on a felt buffer or with a piece of fine sandstone or hone.

Shop Sawing. — Marble blocks are recut in the shop to various shapes
and dimensions. A perforated circular saw, a diamond circular saw, or a
single blade in a straight-cut gang frame may be employed. A perforated-
steel circular saw employing sand or steel shot as abrasive cuts fairly
well, but in many shops it is now replaced by the more rapidly cutting
diamond saw. Circular diamond saws (see figure 40) are 20 to 72 inches
in diameter. The first cost is high, but with care the cost of maintenance
is not excessive. They occupy little space and saw rapidly. An abun-
dance of water is necessary for successful operation, and care must be
exercised to avoid overcrowding. Two diamond saws adjustable for
width may be arranged to work simultaneously on the same shaft.

MARBLE

221

Planing. — Planers are used for cutting moldings and cornices. Usu-
ally the cutting tool is stationary, except for the lateral or vertical
movements necessary for adjustment. The marble slab is carried on a
traveling bed beneath the tool, which scrapes it to the desired thickness
and to a shape governed by the contour of the tool. A great deal of this
work is now done with Carborundum machines.

Fig. 40.

A diamond saw 6 feet in diameter equipped with 125 diamond teeth sawing a
block of marble. (Courtesy of Vermont Marble Company.)

Machining with Carborundum Wheels. — Silicon carbide used as an
abrading- or grinding agent occupies an important place in all modern
marble shops. Carborundum wheels run at high speed, and an abundant
supply of water is directed upon the cutting edge. For straight slabs or
blocks, cutting wheels of several types are in use. The smaller ones
consist of solid Carborundum, or they may have steel centers. Large
wheels are made of iron or steel and have inserted teeth. Other wheels
have steel centers, with rims of silicon carbide which are thicker than the
steel. They are used until the rim is worn down to the thickness of the

222 THE STONE INDUSTRIES

steel, then they may be rerimmed. Carborundum machines are capable
of varied adaptations and can cut curved work, moldings, cornices, and
balusters with great success. The wheel of the machine is a negative of
the desired pattern. The marble block travels on the machine bed
beneath the wheel, which cuts it to the desired shape ; or it may be placed
on a ball-bearing plate and held against the revolving wheel. In cutting
balusters the marble and the Carborundum wheel are brought into
contact while rotating in opposite directions. The peripheral velocity
of the wheel is approximately 5,000 feet a minute, while the baluster
rotates at about 100 revolutions a minute. In fluting or in making
balusters it is advantageous to rough out marble to the general shape
desired before working it with a wheel. If the wheel must remove
considerable material the process is best divided into two operations. A
6 to 10 grit may be used for the roughing operation, which may remove
stone to a depth of three fourths inch under favorable circumstances.
For the finishing cut a 40-grit wheel usually is employed.

Cutting Columns. — Two principal methods are employed for cutting
marble columns. A drum column-cutter is a circular steel drum which
rotates on a vertical axis. Sand or steel shot may be used as the cutting
agent, or the drum may have diamond teeth. The largest diamond-
toothed drum column-cutter on record was used in cutting columns for
the Lincoln Memorial in Washington, D. C. They are 7 feet 5 inches in
diameter and were prepared in sections, each 58 inches long. The drum,
which had 80 diamond teeth, completed a section in 4 to 5 hours.

Drum column-cutters give satisfaction for short columns or for short
sections, as described above. For large monoliths a lathe must be
employed. The marble generally is roughed out by hand to within one
half inch of the finished diameter before being placed in the lathe. As
the column rotates shaping is accomplished with a cutting tool similar to
that used in ordinary machine lathes for turning metal shafts. Actuated
by worm gear or other device, the tool travels slowly back and forth.
For polishing plain columns a lathe may also be used, though fluted
columns are rubbed or polished by hand.

Cutting and Carving. — All complicated patterns or other irregular
designs must be cut by hand. Much of the straight and simple cornice
and molding work formerly shaped with hand tools is now manufactured
with planers or Carborundum machines. Hand carving may be done
with hand tools and hammers but is accomplished much more
rapidly with pneumatic tools.

Sand blasting is commonly used for lettering headstones. A shield
with an opening the size and shape of the inscription area is placed over a
monument. In early practice steel letters were glued on the surface of
the rock in proper position, and a sand blast directed at high pressure
against this surface for a few moments cut down the entire area except

MARBLE 223

that protected by the steel. A httle hand trimming was necessary to
correct irregularities caused by varying hardness of the stone. A more
modern practice, employing a rubberlike "dope" instead of steel, has
been described in the preceding chapter on granite. Much time is saved
by the sand-blasting method, especially when many monuments of the
same size and shape are manufactured.

Handling Material. — Overhead electric traveling cranes are widely
used for handling heavy material. In many shops small stock is handled
with great facility by means of small hand-operated trucks.

WASTE IN QUARRYING AND MANUFACTURE

Regardless of the high quality of any marble deposit there is always
a certain percentage of loss, owing to processes involved in quarrying,
trimming, and manufacture. Imperfections that are present in most
deposits result in further waste. In fact, the final product may be much
less than half the gross amount quarried. The problem of waste is
therefore vitally important to every producer.

To minimize the heavy burden waste disposal places upon his industry
the marble producer first directs attention toward all types of improved
equipment and modern methods of excavation which tend to keep the
proportion of waste to a minimum; he then seeks all possible outlets for
marketing unavoidable waste. The first phase of the problem is pre-
vention of waste; the second is utilization of waste.

Prevention of Waste. — The chief causes of waste are natural imper-
fections, such as joints, strain breaks, impurities, and lack of uniformity
or attractiveness in color and texture. Systematic prospecting and
development of the best beds in a deposit are important steps toward
reducing waste. Making quarry walls parallel to major rock structures,
such as joint systems, is equally important. When quarrying steeply
inclined beds and maintaining a level floor it may be found desirable to
separate blocks parallel to the bedding, to maintain uniformity in the
quality of material in each block. When angular blocks are thus
produced, much waste results if they are cut into cubic stock, as the
corners must be thrown away; when cut into thin slabs waste may be
much less. Various problems of this nature confront every marble
producer.

The more common impurities in marble are silica, pyrite, and mica.
These minerals tend to occur in definite zones or beds, the more impure of
which may be separated and rejected by making cuts parallel to the
bedding. If bands or streaks of undesirable minerals pass diagonally
through blocks, waste may be excessive.

A condition of strain within a marble mass has in certain places
caused so great a proportion of waste that workings have been abandoned.
Usually the rock is under severe compressive stress in one direction only.

224 THE STONE INDUSTRIES

Quarrying relieves the stress at certain points, and consequent expansion
may cause fracturing. Furthermore, expansion of one mass that is in
rigid connection with the main mass still under compression may cause
irregular or oblique fractures to form between the two masses. To
overcome heavy losses from this cause attempts have been made to afford
relief by uniform expansion of as large a mass as possible at once. To
this end, a line of closely spaced, deep drill holes is projected along each
side of the quarry parallel to the direction of compression, and a similar
line across the quarry at right angles to the first line. The rock slowly
expands, crushing the webs between the drill holes and closing the holes
in the transverse row. Some benefit has resulted from the method,
but the problem of overcoming strain breaks has not yet been satis-
factorily solved.

Utilization of Waste. — Although the proportion of waste may be kept
at a minimum by the adoption of economical quarry methods and use of
efficient machinery, the unavoidable waste may still be large. Many
manufacturers in various lines of industry have found that the fabrication
and sale of byproducts from materials otherwise wasted have placed
their industries on a profitable basis. Extensive waste heaps at many
marble quarries testify to the need of greater development along the line
of utilizing as well as avoiding waste. Marble producers are peculiarly
fortunate, in view of the wide field of usefulness for their waste products.
Many commercial marbles are pure calcium carbonate, the uses for which
are very numerous. Some waste is now consumed for burning into lime,
as crushed stone, as agricultural limestone, and in various other ways.
The many potential uses are covered in detail in a later chapter on
crushed and broken limestone.

MARKETING MARBLE

All high-grade marbles have a nationwide market range. Marketing
is somewhat complex, because there are at least five types of agencies
for this purpose. To the first group belong the so-called wholesalers, who
sell marble to the trade chiefly in blocks or as sawed stock. The second
consists of manufacturers who do not own quarries but buy marble
blocks and finish them. Interior marble usually is both finished and set
by them. A third group comprises dealers or contractors who have
neither quarries nor mills but buy finished marble and sell it to cus-
tomers, set in place. Producers who have quarries but no finishing mills
or shops form the fourth agency. They sell their product in blocks to
wholesalers or manufacturers. The fifth and largest group is composed
of manufacturing producers who have quarries, mills, and shops, and
engage in any and all activities of the trade. The merchandising of
unfinished marble within the trade has no set rule or established general
customs. A wholesaler sometimes sells rough blocks direct to owners

MARBLE

225

of buildings in which the marble is to be used, and the owners have the
material sawed and finished.

Marble in the block and in sawed slabs more than 2 inches thick is
sold by the cubic foot ; slabs 2 inches thick and less are sold by the square
foot. To be "merchantable" blocks usually must be at least 5 or 6 feet
long, 3 or more feet wide, and 2 or more feet thick. In some localities a
standard block is 7 by 5 by 4 feet, but great variations in size may occur.
Measurements should as nearly as possible exclude surface irregularities.
Contracts for finished marble in place are usually on a lump-sum
basis. Much of the marble produced is sold on large contracts closed long
before time of delivery.

Marble is classified as to kinds or varieties, and each kind often
exhibits enough variation to require separation into two or more grades.
Rare, beautiful marbles are high-priced but have a limited market ; those
agreeable in tone, texture, and finish and readily obtainable in large
quantities bring a fair price and have a wide market.

IMPORTS AND EXPORTS

The following table compiled by the United States Bureau of Mines
gives imports of marbles for consumption in this country during recent
years :

Marble, Breccia, and Onyx Imported for Consumption in the United States,

1924-1937, BY Kinds

Year

In blocks

Slabs or paving
tile

All other
manu-
factures

Mosaic
cubes

Total
value

Cubic
feet

Value

Super-
ficial feet

Value

1924

654,706

$1,279,351

309,999

$ 97,935

$205,353

$13,158

$1,595,797

1925

642,226

1,327,439

671,561

210,072

257,382

15,265

1,810,158

1926

864,895

1,789,570

403,458

222,230

438,712

7,028

2,457,540

1927

959,241

2,526,582

925,792

306,696

561,990

9,218

3,404,486

1928

586,069

1,673,363

845,464

310,785

483,071

6,126

2,473,345

1929

678,759

1,615,869

649,899

253,267

566,010

1,908

2,437,054

1930

718,233

1,581,839

591,616

254,179

329,279

12,157

2,177,454

1931

252,457

592,342

442,189

164,346

198,833

8,484

964,005

1932

153 , 828

319,088

232,264

71,832

64,724

455,698

1933

63,482

197,472

155,492

66,825

49,769

203

314,269

1934

19,046

126,320

76,184

27,961

32,222

239

186,742

1935

52,573

228,178

85,092

29,846

40,055

1,697

299,776

1936

60,956

257,634

150,364

58,979

43,879

140

360,632

1937

75,467

297,989

214,588

67,789

69,403

180

435,361

226 THE STONE INDUSTRIES

Exports of marble in block form are very much smaller than imports,
averaging about 65,000 cubic feet a year.

TARIFF

The Tariff Act of 1930 provides a duty of 65 cents a cubic foot on
marble in rough blocks and $1.00 a cubic foot if sawed or dressed and over

2 inches thick. Sawed slabs of various sizes and thicknesses carry duties
of from 8 to 13 cents a superficial foot, with an additional charge of

3 cents if rubbed and 6 cents if polished. Manufactured articles, con-
sisting chiefly or entirely of marble, carry a duty of 50'per cent ad valorem.
The duties are essentially the same as under the Tariff Act of 1922.

PRICES

Marbles vary greatly in quality and therefore in price. The price
range may be $1.50 to $7, or even more, a cubic foot. American marbles
for exterior building purposes average about $2 a cubic foot in rough
blocks. Prices of interior rough blocks at the quarry are quite variable,
ranging from $2 to $7 and averaging about $2.40 a cubic foot. Monu-
mental stock in rough blocks averages about $2 to $3 a cubic foot, though
not much domestic marble is sold in this form. Verde antique in large,
sound blocks of attractive color and capable of a fine polish commands
prices of $6 to $8 a cubic foot at the quarry. Onyx marbles vary greatly
in price, depending on appearance and size of blocks. The price may
range from $5 to $15 a cubic foot.

French and Italian marbles sell in New York at $4.50 to $11.50 a
cubic foot depending on quality. In 1931 second-quality Italian marble
was selling at $4.75 to $5.75 a cubic foot. Belgian black marble has sold
in New York at about $1.75 a cubic foot in rough blocks, though in 1929
and 1930 the price was much higher.

Bibliography

The following bibliography comprises the more important books and periodicals
pertaining to marble and the marble industry:

AuBURY, Lewis E. The Structural and Industrial Materials of California. Cali-
fornia State Min. Bur. Bull. 38, 1906, pp. 95-110.
Bayley, W. S. Geology of the Tate Quadrangle, Georgia. Geol. Survey of Georgia

Bull. 43, 1928, 170 pp.
Bowles, Oliver. The Technology of Marble Quarrying. U. S. Bur. of Mines Bull.

106, 1916, 174 pp.
BuRCHARD, Ernest Francis. Marble Resources of Southeastern Alaska, with a

Section on the Geography and Geology by Theodore Chapin. U. S. Geol.

Survey Bull. 682, 1920, 118 pp.
Granite, Marble, and Other Building Stones of the South. Manufacturers

Record 61, vol. 7, pt. 2, 1912, pp. 59-60.
Butts, Charles. Variegated Marble Southeast of Calera, Shelby County, Ala.

Contributions to Economic Geology, 1910, pt. 1, U. S. Geol. Survey Bull. 470,

1911, pp. 237-239.

MARBLE 227

California State Mining Bureau. Marble. Bull. 38, 1906, pp. 95-114.
Dale, T. Nelson. The Commercial Marbles of Western Vermont. TJ. S. Geol.
Survey Bull. 521, 1912, 170 pp.

The Calcite Marble .and Dolomite of Eastern Vermont. U. S. Geol. Survey

BuU. 589, 1915, 67 pp.

Danekbr, Uerome G. The Romance of Georgia Marble. Thompsen-Ellis Co.,
New "york, 1927, 79 pp.

IDarto^, N. H. Marble of White Pine County, Nev. Contributions to Economic
Geology, 1907, pt. 1, Metals and Nonmetals except Fuels, U. S. Geol. Survey
Bull. 340, 1908, pp. 377-380.

Eckel, Edwin C. Building Stones and Clays; Their Origin, Characters, and Exami-
nation. John Wiley & Sons, Inc., New York, 1912, pp. 166-181.

Gordon, Charles H. The Marbles of Tennessee. State Geol. Survey of Tennessee
Extract (D) from Bull. 2, Preliminary Papers on the Mineral Resources of
Tennessee, 1911, 33 pp.

Gordon, Charles H., Dale, T. Nelson, and Bowles, Oliver. Marbles of East
Tennessee. Pt. 1, Occurrence and Distribution; pt. 2, Constitution and Adap-
tations of the Holston Marbles; pt. 3, Technology of Marble Quarrying. Div.
of Geol. State of Tennessee Bull. 28, 1924, 264 pp. (Prepared in cooperation
with the U. S. Geol. Survey, U. S. Bur. of Mines, and the Div. of Geol. State
of Tennessee.)

Kessler, D. W. a Study of Problems Relating to the Maintenance of Interior
Marble. U. S. Bur. of Standards Tech. Paper 350, 1927, 91 pp.

Physical and Chemical Tests of the Commercial Marbles of the United

States. U. S. Bur. of Standards Tech. Paper 123, 1919, 54 pp.

Permeability of Stone. U. S. Bureau of Standards Technol. Paper 305,

1926, 172 pp.

Lent, Frank A. (compiled by). Trade Names and Descriptions of Marbles, Lime-
stones, Sandstones, Granites, and Other Building Stones Quarried in the United
States, Canada, and Other Countries. Stone Publishing Co., New York, 1925,
41pp.

McCallie, S. W. a Preliminary Report on the Marbles of Georgia. Geol. Survey
of Georgia BuU. 1, 2d ed., 1907, 126 pp.

Merrill, George P. The Onyx Marbles; Their Origin, Composition, and Uses
Both Ancient and Modern. U. S. Nat. Museum Rept. for 1893, 1895, pp.
539-585.

Stones for Building and Decoration. John Wiley & Sons, New York, 1910,

551 pp.

Report on Some Carbonic Acid Tests on the Weathering of Marbles and

Limestones. Proc. U. S. Nat. Museum, vol. 49, 1916, pp. 347-349.

Merrill, George P., and Mathews, Edward B. The Building and Decorative
Stones of Maryland, Containing an Account of Their Properties and Distribution.
Maryland Geol. Survey, vol. 2, pt. 2, 1898, pp. 99-119, 171-197.

Mineral Resources of the United States. Chapters on Stone, containing statistical
and general information, published each year by the U. S. Bur. of Mines, Wash-
ington, D. C. (Prior to 1924 published by the U. S. Geol. Survey, Minerals
Yearbook since 1931.)

Newland, D. H. The Quarry Materials of New York — Granite, Gneiss, Trap, and
Marble. New York State Museum Bull. 181, 1916, pp. 176-208.

Parks, William A. Report on the Building and Ornamental Stones of Canada.
Canada Dept. of Mines, Mines Branch, vol. 1, no. 100, 1912, 376 pp.; vol. 2,
no. 203, 1914, 264 pp. ; vol. 3, no. 279, 1914, 304 pp. ; vol. 4, no. 388, 1916, 333 pp. ;
vol. 5, no. 452, 1917, 236 pp.

228 THE STONE INDUSTRIES

Parks, Bryan, Hansell, J. M., and Bonewits, E. E. Black Marbles of Northern
Arkansas: Arkansas State Geol. Survey Inf. Circ. 3, 1932, 51 pp.

Prouty, William Frederick. Preliminary Report on the Crystalline and Other
Marbles of Alabama. Geol. Survey of Alabama Bull. 18, 1916, 212 pp.

Renwick, W. G. Marble and Marble Working. Crosby, Lockwood & Sons,
London, 1909, 226 pp.

Richardson, Charles H. Building Stones and Clays. Syracuse Univ. Book Store,
Syracuse, 1917, pp. 134-228.

Sewell, John Stephen. Chapter on Marble; Marketing of Metals and Minerals,
edited by Spurr and Wormser. McGraw-Hill Book Company, Inc., New York,
1925, pp. 415-426.

Stone (a monthly magazine devoted to the building and monumental stone industries).
Stone Publishing Co., New York.

Tenney, J. B. The Mineral Industries of Arizona. Univ. of Arizona Bull. 125,
1928, pp. 107-108. (Describes onyx.)

Through the Ages. (A magazine devoted to the uses of marble, its universal adapta-
bility, beauty, permanence, and economy.) Nat. Assoc. Marble Dealers,
Baltimore. (Discontinued in 1932.)

Warnes, a. R. Building Stones; Their Properties, Decay, and Preservation.
Ernest Benn, Ltd., London, 1926, 269 pp.

Watson, John. British and Foreign Marbles and Other Ornamental Stone. Cam-
bridge University Press, 1916, 485 pp.

Weigel, W. M. Application of the Wire Saw in Marble Quarrying. Am. Inst.
Min. and Met. Eng. Tech. Pub. 262, 1930, 7 pp.

CHAPTER X
SLATE

DEFINITION

Slate, like marble, belongs to the metamorphic group of rocks.
According to the standard definition established by the American
Society for Testing Materials, it is "a microgranular crystalline stone
derived from argillaceous sediments by regional metamorphism and
characterized by perfect cleavage entirely independent of original bedding,
which cleavage has been induced by pressure within the earth." In
simpler language, it may be defined as a fine-grained rock derived fronT"**!
clays and shales and possessing a cleavage that permits it to be split '^
readily into thin, smooth sheets. The term includes materials differing
widely in color and varying considerably in chemical and mineralogical
composition.

ORIGIN

Except for certain rare varieties of igneous origin formed from volcanic
ash or igneous dikes, slates have originated from sedimentary deposits
consisting largely of clay. Minerals originally present with the clay in
limited quantities include quartz; mica; feldspar; zircon; compounds of
iron, lime, and magnesia; and carbonaceous matter, together with
silicates other than those named. Through many centuries the clays
carried by rivers were laid down as bedded deposits in deep water, and
in later ages they may have been covered with beds of sand, gravel, or
limestone. The pressure of such superimposed beds gradually consoli-
dated the clays into deposits of shale, a laminated rock consisting essen-
tially of clay but without the splitting properties of slate.

Many shales have been subjected to intense metamorphism and have
thereby been altered into slates. The changes brought about by this
process were both chemical and mechanical. The constituent minerals
were transformed into new minerals, such as mica, quartz, chlorite,
magnetite, graphite, tormaline, and various others, and the first three
usually predominated. The mica and chlorite occur as microscopic
flakes. The intense pressure tended to compress the rock and cause it to
expand at right angles to the direction of pressure. The innumerable
tiny flakes of mica and chlorite, formed as a result of metamorphism,
assumed positions with their flat surfaces lying in the plane of flowage
or elongation. Such parallelism of mineral grains resulted in that

229

230 THE STONE INDUSTRIES

tendency to split with ease in one direction which has been termed
"slaty cleavage." As the rock usually is folded and contorted slaty
cleavage may intersect bedding planes at various angles, a feature which
distinguishes slate from shale, for the latter rock shows no tendency to
split, except in a direction parallel to the bedding.

If the process of metamorphism is so incomplete that much of the
clay remains unaltered the slate is termed "clay slate." When the
process is carried farther and little or no clay remains the rock is called
"mica slate." This type possesses greater strength, is denser and more
resistant to absorption, and therefore more enduring than clay slate.
It constitutes practically the entire supply of commercial slate in the
United States. Continued intensive metamorphism of mica slate pro-
duces more complete recrystallization, forming coarser grains and
developing in the rock a schistosity commonly wavy and irregular. Such
highly metamorphosed rocks are known as "phyllites" or "mica schists."

MINERALOGICAL COMPOSITION

One of the most abundant minerals in mica slate is secondary musco-
vite, or white mica, commonly termed "sericite" — a hydrous silicate of
potash and aluminum. It appears in very minute flakes whose outlines
are recognizable only under a microscope with high magnification.
Small grains of quartz also abound and are distributed regularly among
the mica flakes. Usually considerable amounts of the micalike mineral
chlorite are also present. Chlorites are of various kinds, the more
common being hydrous silicates of aluminum and iron or magnesium.
Clay, or kaolin, usually occurs only in small quantities in mica slates,
though it may be quite abundant in clay slates. Minerals of minor
importance are rutile, andalusite, hematite, pyrite, carbonaceous matter,
graphite, feldspar, zircon, tourmaline, calcite, dolomite, and siderite;
very small quantities of many other minerals are commonly identified.
The general range of mineral composition is shown in the following table.

Mineral Composition of Average Slate

Per cent

Mica (sericite) 38-40

Chlorite 6-18

Quartz 31-45

Hematite 3- 6

Rutile 1- IM

CHEMICAL COMPOSITION

Results of many analyses indicate that clays, shales, and slates
differ little in chemical composition, as the changes that occur during
metamorphism are confined largely to rearrangement of chemical elements
into new minerals and to changes in such physical characteristics as
hardness and cleavage. Chemical composition, while of scientific

SLATE 231

interest, has so little economic significance that detailed chemical analyses
tell little or nothing of the true value of slates. Their commercial
adaptability depends chiefly on mineralogical composition, structure, and
texture. The range in composition of average slate, constituents of less
importance being omitted, is as follows:

Range of Chemical Composition of Slate

Per cent Per cent

Silica 50-67 Soda 0.5-4

Alumina 1 1-23 Magnesia 0 . 5-5

Ferric oxide 0 . 5-7 Lime 0 . 3-5

Ferrous oxide 0.5-9 Water above 110°C 2.5-4

Potash 1.5-5.5

PHYSICAL PROPERTIES

Color. — Slates are of various colors, the most common being light and
dark gray, bluish gray, blue-black, red, green, purple, and mottled.
Yellow, brown, and buff are occasionally found but as these colors usually
have resulted from weathering, the slates are rarely of marketable quality.
The color of a slate is determined by its chemical and mineralogical
composition. Gray and bluish gray are due chiefly to the presence of
carbonaceous material and other colors principally to iron compounds.
Slates containing large proportions of finely divided carbonaceous matter
are black. Permanence of color has considerable economic importance,
for although some slates maintain their original colors for many years,
others change to new shades within a comparatively short time. Such
changes may be due to the presence of small quantities of iron-lime-
magnesia carbonates, which decompose readily with the formation of the
yellow hydrous iron oxide, limonite. Moderate, uniform fading may not
be detrimental to appearance and may even produce a more pleasing
effect. However, in replacing broken slates which are subject to color
changes it may be difficult or impossible to match colors.

Green slates are of two types, the unfading and the fading, or "sea
green." The former maintains a green color indefinitely; the latter when
freshly quarried is greenish gray, which after a few years' exposure
changes to brownish gray or buff. This change is not regarded as
evidence of deterioration; it is, in fact, a weather-aging effect that many
architects prefer. Circular and oval green spots occurring in certain
New York and Vermont slates have long attracted attention. They
are probably the result of chemical changes, such as reduction of iron
oxide caused by decay of organisms.

Strength. — Slate, consisting as it does chiefly of very small overlapping
flakes consolidated under pressure, is a strong rock. Tests are commonly
made of compressive strength; elasticity; and modulus of rupture, or
breaking strength. The last property, which is most significant for a
majority of the uses to which slate is put, is determined by measuring the

232 THE STONE INDUSTRIES

breaking load applied at the middle of a bar of slate supported near the
ends. The modulus of rupture of commercial slates is 7,000 to 12,000
pounds a square inch.

Porosity. — Most mica slates of good commercial quality are practically
impervious to moisture, their porosity ranges from 0.02 to about 0.45
per cent. They are therefore well-adapted for sanitary uses.

Electrical Resistance. — Uniformly clear slate free from spots, veins,
or iron-bearing minerals and low in carbon is highly resistant to electric-
ity. Moisture increases its conductivity; hence after quarrying it
usually is seasoned at least three months before use.

Durability. — High-grade slates, consisting essentially of stable silicate
minerals, which are very resistant to weathering, are among the most
durable building materials. However, to obtain the most enduring types
careful selection must be made. Calcium carbonate apparently is the
least desirable constituent of slates designed to resist long exposure,
especially to sulphur fumes, for sulphur trioxide acting on calcium
carbonate forms calcium sulphate, or gypsum, a mineral which expands
greatly during crystallization with disruptive effects. Medium-grade
slates are serviceable for 25 to 50 years, and the highest grades will far
outlive most structures on which they are placed. Ferguson'^ has
recorded that slate quarried near Delta, Pa., in 1734 was used for roofing
seven buildings in succession. In 1930, the seventh building, a hog pen,
was located near Delta. A sample of the slate has been rescued from
this lowly use and is now on exhibit at the United States Bureau of
Mines, Washington, D. C. After nearly 200 years in service it shows no
evidence of deterioration. Even longer periods of use have been known
in the Old World. A slate-roofed Saxon chapel standing in Bradford-on-
Avon, Wiltshire, England, was built in the eighth century, and though
moss-covered it is still in good condition after 1,200 years of constant
exposure to climatic changes. Slate tombs high in the Alps near Oisans,
France (which, from money and jewels found in them, archeologists have
concluded were constructed about 500 B. C), are still in good condition.

STRUCTURAL FEATURES

Bedding. — The shales from which slates originated were deposited
primarily as clay beds. The beds of shale, at first horizontal, were
tilted by subsequent earth movements, and the intense metamorphism
that converted them into slates folded and contorted them. Differences
in conditions of deposition often resulted in variations in color and
texture of successive strata and such variations make possible tracing
folds and contortions on a quarry wall. Bands representing beds of
darker slate are known among quarrymen as "ribbons." In many

36 Ferguson, E. G. W., Peach Bottom Slate Deposits, Pennsylvania. Min. World,
vol. 33, 1910, p. 183.

SLATE 233

deposits the original bedding has been so obHterated that it is extremely
difficult to trace. Recognition of beds is important, for while the slate
in any one bed tends to be uniform for considerable areas, it may differ
greatly in successive beds. Therefore, for the proper development of a
deposit of desirable slate the original bedding must be followed. Thus,
in the Pen Argyl district of Pennsylvania quarries are situated on the
"Albion vein," the "Diamond vein," the "United States vein," or the
"Pennsylvania vein," each of which is of limited thickness. These
so-called veins, or beds, are vertical or dip at steep angles, and their
direction may change with depth. The folds (inclination) of beds have
direct bearing on the location of quarry openings and on plan of
development.

Slaty Cleavage. — Slaty cleavage is the structure which above all
others differentiates slate from other rocks and gives it economic value.
A true slate can be split into thin sheets with smooth, even surfaces.
Some Pennsylvania slates can be split as thin as one thirty-second of an
inch, but such sheets are too thin for practical use. In the manufacture
of blackboard slates uniform, smooth slabs 4 by 6 feet or larger may be
split readily to a thickness of three-eighths or one-half inch. In some
deposits slaty cleavage is less pronounced than in others and the rock
splits with greater difficulty.

Slaty cleavage may parallel beds, though commonly it intersects them
at angles of 5 to 30° and may even cross them at right angles. Most
slates split with the greatest ease when freshly quarried. Repeated
freezing and thawing destroy the splitting quality.

Grain. — Although they split most readily in the direction of slaty
cleavage, many slates have a second direction of splitting which, is less
pronounced, but has economic significance. In slate literature this
second direction is called the "grain," though quarrymen use the terms
"sculp" or "scallop." It is approximately at right angles to slaty
cleavage, usually nearly parallels the cleavage dip, and may commonly
be recognized by lines or striations on the cleavage surface. It seems
to result from mineral orientation, for many minerals lie so that their
flat faces parallel the direction of the slaty cleavage and their long axes
parallel the grain. In some deposits the grain is distinct, whereas in
others there is practically none.

The relative ease with which slate splits in the direction of grain
compared with the difficulty with which it breaks in any other vertical
plane has distinct practical value in subdividing the larger blocks and
reducing them to convenient sizes. In roofing slate the grain should
always parallel the long sides, so that breakage, which is most likely to
occur in the direction of grain, will parallel the dip of the roof.

Joints. — Joints, seams, or "headers" are more or less regular parallel
systems of cracks, or fractures, in rocks, caused by pressure or movement.

234 THE STONE INDUSTRIES

The origin of joints in rocks has been covered in some detail in the
chapter on granite. They may parallel the strike of beds or the direction
of dip, or may run diagonally. There are also horizontal joints, some-
times termed "bottom" or ''flat joints." In the Pennsylvania deposits
curved, or undulating, joints have been noted. An open seam that
parallels the bedding is termed a "loose ribbon."

Ribbons. — "Ribbons" are dark bands a fraction of an inch to several
inches in width intersecting blocks of slate at various angles. They
represent minor beds of somewhat different composition from the main
body of rock. As they always parallel the bedding they serve as markers
or indicators that assist in tracing folded or otherwise contorted beds.
They are characteristic of the Lehigh and Northampton County, Pa.
slates. The "soft-vein" ribbons in these slates usually are rich in
carbonates and carbon and as a rule, disintegrate more readily than
clear slate. Ribbon slate is therefore used for second- or lower-grade
roofing and as structural slate. In "hard-vein" slate, however, most of
the ribbons resist weathering, and this variety may be employed for high-
grade roofing or other exterior uses.

IMPERFECTIONS

Curved or Irregular Cleavage. — Cleavage in other than a straight,
even plane is undesirable in slate, though a small curvature is permissible
for small roofing slate. Blackboards and structural slate products are
subdivided by splitting, and a crooked split necessitates much labor to
reduce the slab to an even plane. A block of slate having curved cleavage
may produce only three slabs of a given thickness, whereas a straight-
splitting block of the same thickness may produce five or six similar slabs.

Slip or False Cleavage. — Slip cleavage is a tendency to split along
incipient joint planes or seams. It usually runs diagonal to the slaty
cleavage, causing waste.

Veins. — Veins are common in slate quarries. They may follow
bedding or cleavage planes, intersect them at various angles, or be very
irregular. Veins of quartz are termed "flints" by quarrymen. Calcite
or "spar" veins are common, as are also those filled with a mixture of
quartz, calcite, dolomite, and possibly chlorite and biotite.

Impurities. — One of the most undesirable impurities in some slates, is
calcium, usually in carbonate form. Its harmful effects have been
mentioned under "Durability." Iron carbonate is sometimes present,,
and its decomposition not only weakens the state, but the resulting ironi
oxides may cause stains. Iron sulphides may oxidize and form spots
and stains. The stabihty of the iron sulphides has been discussed in
some detail in the chapter on marble. The oxidation of iron-bearing
minerals, especially ferrous carbonate, often causes color changes.
Nodules oi flint or q^uartz encountered ia some slates greatly increase the.

SLATE 235

difficulty of working. Carbon usually is regarded as an agent of dis-
integration and is particularly undesirable in electrical slate, as it acts as a
conductor and promotes leakage of current.

USES

Roofing. — In early years roofing was, with minor exceptions, the only
use for slate, and it is still a very important one. Slate is durable, attrac-
tive, noninflammable, and adaptable to the most artistic architectural
effects. There are two grades of roofing slates — standard and the so-
called architectural. Material for standard slates should have straight,
uniform, smooth cleavage, and the color should be permanent, or if it is
subject to change, uniform color aging without deterioration is usually
demanded. In the United States standard slates are sold by the "square "
— enough slate to cover 100 square feet of sloping-roof surface with a
3-inch head lap. In France and England the unit is a "mille," consisting
of 1,200 slates of any given size and 60 additional to cover loss by break-
age. Standard slates range in size from 6 by 10 to 4 by 24 inches, and in
thickness from three-sixteenths to one-fourth inch. The number of
slates required for a square ranges from 85 to 686, according to size.
The weight of a square of average standard roofing slate is about 650
pounds.

Architectural grades have attained prominence during the past 10
years. They meet the demand of modern architecture for rough, rugged
building materials rather than for the smooth, mathematically exact types
formerly popular. Architectural slates may be 1 to 2}4 inches thick
and 2 to 4 feet long. Surfaces may be rough and uneven and colors
variable. For large structures the heavier slates are placed near the
eaves with the smaller and thinner ones toward the ridge. Slates thus
graduated in size and of a variety of blending colors produce very beautiful
architectural effects. Slate slabs set in mastic are also used extensively
for flat roofs, roof promenades, and terraces.

Mill Stock. — While roofing was originally the dominant branch of the
slate industry many other uses have developed. Slate worked up into
slabs of various sizes and shapes is classed as "mill stock." The different
products are described in following paragraphs.

Blackboards and School Slates. — Slate suitable for blackboards and
feuUetim beards must be soft, and also of uniform color and texture.
Sueh material is obtained chiefly from what is known as the "soft-vein"
region of Lehigh and Northampton Counties, Pa. The soft vein is the
northern slate belt, which includes the region in and about Bangor,
East Bangor, Pen Argyl, Danielsville, Slatington, and Slatedale. This
comparatively small area, about 30 miles long, provides most of the
world's production of blackboard slate. Because of their smoothness,

236 THE STONE INDUSTRIES

uniformity, permanence, and attractiveness, slate blackboards are
superior to all other types now in use.

School slates were once commonly used in America, but demand for
them has greatly declined. Foreign demand is considerable, and most of
those now manufactured are exported. As school slates are small their
manufacture permits utilization of the smaller pieces of slate, many of
which otherwise would be wasted. Slate for this purpose is similar to
that used for blackboards, and deposits are confined largely to the same
area.

Structural Slate. — Although roofing slate ordinarily is regarded as
structural material, a distinction is made in the slate industry, the term
"structural slate" being employed for products used chiefly for interior
structural and sanitary purposes. The chief products are mantels,
floor tiles, steps, risers, flagging, skirting or baseboard, window sills,
lavatory slabs, billiard and other table tops, wainscoting, hearths, well
caps, vats, sinks, laundry tubs, grave vaults, sanitary ware, refrigerator
shelves, flour bins, and dough troughs. Soft, even-grained slate, prefer-
ably not highly fissile, is required for such purposes.

Floors and Walks. — Slate is being used in increasing quantities for
ornamental flagging in sidewalks, porches, and sun parlors. Some is
honed and fitted for close joints, but much is used with split or "quarry
cleft" surface and in irregular outline, which permits utilization of much
slate that heretofore has been discarded as waste.

Electrical Slate. — Certain types of slate have very high dielectric
strength and on this account are suitable for electric panels and switch-
boards. Their superior qualities are strength, rigidity, toughness, and
easy workability. Also, they can be matched easily when switchboards
are enlarged. Electrical slate should be low in magnetite, carbon, and
other low-resistance minerals and capable of being cut and drilled
easily without scaling.

Granules and Flour. — Slate crushed to granular form is employed
widely in the manufacture of slate-surfaced composition roofing. Red,
green, blue-black, and gray granules are manufactured from slates having
these natural colors. Granules are also artificially colored to provide
materials for the highly colored roofs demanded by many architects
and home builders. Ground slate is used for surfacing tennis courts
and other playgrounds. Pulverized slate, known as "slate flour," is
used as a filler in paints, road asphalt-surface mixtures, roofing mastic,
and various other products.

HISTORY OF INDUSTRY

European History. — One of the earliest references regarding the use
of slate concerns a slate-roofed chapel at Bradford-on-Avon, England,
built in the eighth century. In the twelfth century thick, rough Welsh

SLATE 237

slates were used. However, it was not until the latter part of the
eighteenth century that the slate industry attained importance, and even
then methods were crude and wasteful. After 1850, with the develop-
ment of foreign trade and extension of railways the Welsh slate industry
grew rapidly. In France the industry made rapid progress about the
same period.

History in America. — The oldest slate quarry on record in America
was opened near Delta, Pa., in 1734. The first quarry in Virginia was
opened about 1787 to provide slate for the roof of the State Capitol,
and in Georgia the first production was in 1850. From these early
beginnings slate quarrying spread to eastern Pennsylvania, New York,
Vermont, and Maine, and between 1870 and 1880 it became a well-
established industry. Welsh slate workers were the originators of the
industry in several districts.

Although production has assumed fair magnitude it has not increased
proportionally with building construction. This is singular in view of
the adaptability and permanence of slate and the satisfactory service
afforded in its many applications.

Reasons for Slow Growth. — As may be noted from the table on the
following page, which shows production over a period of years, the
industry grew rapidly during 1923, and maintained its increased volume
from 1924 to 1926. In the three following years, which were generally
prosperous, there was decided recession. Lack of sustained activity is
due to various causes. It is to be attributed chiefly to the keen competi-
tion that slate must meet in every line of production — a condition
covered more completely in the section on marketing. Other reasons for
slow growth are excessive waste and high cost of quarrying and manu-
facture. These difficulties are being overcome measurably, as will be
shown later.

GENERAL DISTRIBUTION

The active slate-producing districts of the United States are the
Monson district, Me.; the New York- Vermont district, including Wash-
ington County, N. Y., and Rutland County, Vt. ; the Lehigh district,
including Lehigh and Northampton Counties, Pa., and Sussex County,
N. J.; the Peach Bottom district, including Lancaster and York
Counties, Pa., and Harford County, Md.; and the Buckingham
County (Arvonia) and Albemarle County districts of Virginia. The
geographic locations of these areas are shown in figure 41. These
districts produce roofing slate, and some of them also produce mill
stock, roofing granules, and slate flour. Roofing granules, flour, and
some other products have also been manufactured during recent years in
California, Georgia, Tennessee, and Utah.

238

THE STONE INDUSTRIES

PRODUCTION

The following table prepared by the United States Bureau of Mines
shows sales of slate, by uses, from 1926 to 1937. The total quantity and
value given for each use are the totals of the reports of quarrymen (not

Fig. 41. — Map showing principal slate-producing areas in the United States. (Prepared

by H. Herbert Hughes.)

selling agents), and the value is that f.o.b. quarry or nearest point of
shipment.

Slate (Other Than Granules and Flour) Sold by Producers in the United
States, 1926-1937, by Uses

Roofin

g slate

Mill stock

Total

Other uses*
(value;

Year

Squares

Square
feet

Short tons

(100 square
feet)

Value

(approxi-
mate)

Value

1926

465,900

85,079,087

10,278,130

$4,191,185

$ 73,127

219,950

$9,343,399

1927

468,560

4,949,940

9,287,680

3,519,386

135,448

232,280

8,604,774

1928

483 , 280

5,411,332

9,220,170

3,408,304

184,184

232,380

9,003,820

1929

462,120

4,920,766

9,936,480

3,702,145

124 , 524

241,130

8,747,435

1930

340,140

3,359,939

7,917,220

2,755,530

100,732

173,910

6,216,201

1931

277,700

2,364,861

5,794,380

1,754,054

66,904

138,440

4,185,819

1932

144,410

1,072,255

2,840,020

810,443

23,786

74,490

1.906,484

1933

153,170

967,834

2 , 089 , 650

519,078

28,951

73 , 240

1,515,863

1934

137,010

1,033,164

2,113,620

681,959

26,705

66,570

1,641,828

1935

221,630

1,456,041

2,994,470

849,796

35,333

103 , 690

2,341,170

1936

366,130

2,607,402

4,108,450

1,175,668

55,358

165,110

3,838,428

1937

365,800

2,728,109

4,194,160

1,225,645

73 , 554

167,550

4,027,308

* Includes flagstones, walkways, stepping stones, and miscellaneous slate.

SLATE

239

The following table shows distribution of production by States;
The amounts vary from year to year, but the relative production of the
States is fairly constant. The 1929 figures are shown because they are
probably more typical than those for later years.

Slate Sold by Producers in the United States, 1929, by States and Uses

Opera-
tors

Roofing

Mill stock

Other uses
(value)

State

Squares

(100
square

feet)

Value

Square feet

Value

Total value'

1929

1
2

*
*
*

$ 1,315

3,720

14,670

251,880

151,810

35,460

4,580

$ 38,316

204,362

1,967,428

2,214,869

434,628

61,163

702,740

S 613,996

$ 653,627

214,770

634,169
356,934
875,714

754,135

838,531

Pennsylvania

8,011,080
1 , 222 , 660

2,473,838
614,311

4,798,200
3,704,894

Undistributedt

1,035,156

127

462,120

$4,920,766

9,936,480

$3,702,145

$2,622,267

$11,245,178

* Included under "Undistributed."

t Includes output of States entered as (*) above.

INDUSTRY BY STATES"

Because of the unusual conditions prevailing in 1930, 1931, and 1932,
it is deemed advisable to use 1929 figures to indicate the relative standing
of the various States.

Maine. — Sales of slate in Maine in 1929 were valued at $653,627, or
about 5.8 per cent of the total production-value for the United States.
Production in 1930 was valued at $506,322, in 1931 at $257,619; and in
1937 at $388,521. During recent years two large companies have fur-
nished most of the supply, though others have produced at times.

The slate region of Maine lies in about the center of the State in
southern Piscataquis County near Monson, Blanchard, and Brownsville.
Slate occurs in a belt 15 to 20 miles wide, and the commercial beds lie
south of the central granite area. The strike is in general northeast,
and the dip is very steep, ranging from 80° to vertical. The general
structure is obscure.

Monson District. — Production in Maine is confined almost exclusively
to the vicinity of Monson. The commercial beds are of very fine-grained,

" The geology of the various slate districts is based mainly on U. S. Geol. Survey
Bull. 586, Slate in the United States, by T. Nelson Dale.

240 THE STONE INDUSTRIES

dense, uniform, blue-black slate. The slaty cleavage is vertical and
therefore practically parallels the bedding. Originally open-pit methods
were used, but recent production has been principally from underground
workings.

The largest pit, known as the old Pond quarry, is 500 feet long, 100
feet wide, and 250 to 400 feet deep. This opening intersects about
15 beds of slate interbedded w^ith dark gray or black quartzite. The
structure of the slate does not favor open-pit working, chiefly on account
of the vertical cleavage, which weakens the walls. Obviously, water
entering vertical cleavage planes and freezing therein will cause walls to
spall. Furthermore, rock with vertical cleavage is less capable of
sustaining weight than flat-lying masses and will bulge inward and finally
collapse under intense pressure. On this account, operations in recent
years have been confined to certain thick beds of high quality, and
underground methods have been followed. Details of the method are
given in the section dealing with technology.

Workings adjoining the old Pond quarry have been conducted chiefly
on one bed 9 feet thick dipping at about 10° from vertical. The cleavage
is vertical and nearly parallels the strike of the beds, the angle of inter-
section ranging from 5 to 10°. The grain is vertical and perpendicular to
the cleavage. The 9-foot bed and other parallel beds have been quarried
extensively near the Pond quarry and at other points over a distance of
3 miles to the northwest.

Another series of openings is or has been worked about 1 mile south
of Monson village. The chief bed worked is 10 feet thick, stands vertical,
and strikes N.63°E. The cleavage is vertical and nearly parallels the
strike. The grain is vertical and at right angles to the cleavage. For
many years slate was removed from long, narrow, vertical openings, but
the difiiculty of maintaining safe walls at depths of 300 to 350 feet was so
great, especially in view of the inclined open joints occurring frequently
throughout the district, that underground stoping methods were adopted
and have been employed with success.

Various other openings have been made near Monson, and the general
structure is similar in all deposits. Narrow, vertical beds with vertical
cleavage are the most notable characteristics.

Monson slate is especially adaptable for the manufacture of switch-
boards, panels, and other electrical insulators. Not only has it excep-
tionally high dielectric strength, but it is easily cut and drilled, and the
uniform ebonylike surface is attractive. A large percentage of the total
production in this district is electrical slate, though some blackboards
and a limited quantity of sanitary and structural slate are also manu-
factured. Roofing-slate production has always been small, but this
branch of the industry is attaining greater importance.

SLATE 241

Large, well-equipped finishing mills are maintained in the Monson
district. Electrically driven machinery of the most modern type is
employed to saw, plane, rub, polish, and drill slabs of slate with the
utmost accuracy and precision. Monson slate has won an excellent
reputation for both quality and workmanship. The product is trans-
ported by a narrow-gage railway 6 miles long, connecting with the Bangor
and Aroostook Railroad. Winter weather is severe, and difl&culty is
experienced at times from the heavy snowfall.

North Blanchard District. — Many years ago two large quarries were
operated at North Blanchard about 6 miles west of Monson for produc-
tion of electrical, structural, and roofing slate, but no activity has been
reported during recent years. A series of alternating beds of dark gray
slate and quartzite having a total thickness of 50 to 65 feet strikes
N.25° to 37°E., and dips about 80°. The slaty cleavage parallels both
dip and strike and is at right angles to the grain, which is vertical. The
best beds are 4 to 7 feet thick. The quarries are near the railroad.

Brownsville District. — A dark gray slate was quarried many years ago
in southeastern Piscataquis County near Brownsville. Numerous slate
beds over an area more than 160 feet wide are interbedded with quartz-
ites, as in the other districts. The best beds are 6 to 9 feet thick, run
northeast, and dip about 75°. The cleavage approximately parallels
bedding. Roofing slate was the chief product, but no production has
been reported from this district since about 1914.

New York-Vermont. General Features. — An important slate district
extends from Rutland County west-central Vermont into Washington
County, New York. Slate production in Vermont in 1929 was valued at
$3,704,894, or about 33 per cent of the value of total production for the
entire country. Production in 1930 was valued at $2,463,241, in 1931 at
$1,508,518, and in 1937 at $1,431,798. Roofing slate is the chief product,
but material for floors, walks, mill stock, granules, and slate flour is also
produced in large quantities. Production in New York in 1929 was
valued at $838,531, or about 7.5 per cent of the value of total production
for the United States. In 1930 it was valued at $438,619, in 1931 at
$325,476, and in 1937 at $360,064. Granules and slate flour constitute
about three fourths of the production, and roofing slate one fourth.

Geology. — As the area embraced is a continuous geologic unit, it is
discussed as a whole. The geology of the district is complex. The
slates are of two ages — those of Ordovician age including red, bright
green, and black slates and those of Cambrian age including green,
purple, and variegated slates. In some places the Cambrian rocks pro-
trude through the Ordovician, and intense folding and faulting make the
relationships obscure. The slate beds lie in close folds more or less
overturned to the west with eastward-dipping slaty cleavage. Most of

^42 rtiE STONE 7:ndvstr7e&

the Cambrian roofing-slate quarries are close to the boundairy between the
'Cambrian and Ordovician. In general, the slaty cleavage dips eastward
•30 to 50° and either parallels the beds or crosses them at a low angle.
The grain Or sculp is usually vertical bttt variable in direction in different
'quarries. Close jointing in the dip direction occurs in .pilaces. Quaittz
veins, p'yrite crystals, and dikes appear in some areas.
; ■ Varieties and Uses. — The various types of slate with their distribiition
iand uses are described in following paragraphs.

Sea-green > Slate. — The term "sea-green" is applied ^to a varieity of
'slate 'that w-hen first quarried is light gray to slightly greenish gray, but
^hich after a few years' exposure changes to a buff or brownish gray.
'This color-aging is preferred by some architects and builders. As both
the sea-green and unfading green slates are of Cambrian age and evi-
dently belong to the same period of deposition it is difficult to find a reason
for the difference in degree of permanence in color. Generally, the sea-
green slates are found in the region south of a point about 2 miles north
of Poultney, and the unfading green slates north of that point, but
exceptionally the occurrences are reversed. The difference probably is
due to a change in sedimentation, the southern area having more car-
bonate and the northern less carbonate and more chlorite and pyrite.
Some of the sea-green slates are classed as hard, others as soft. They are
used chiefly for roofing and to a small but increasing extent for floors and
walks.

Unfading-green Slate. — The slate termed "unfading green" is greenish
gray, a color it maintains indefinitely. It contains more pyrite and
magnetite than the sea-green and splits less readily. Unfading-green
slate is confined chiefly, though not entirely, to that part of the slate area
which lies north of Poultney. It is used principally for roofing.

Purple and Variegated Slates. — The so-called "purple" slate is dark
purplish brown, the purple color being attributed to a mixture of the red
of hematite with the bluish green of chlorite. The "variegated" is
greenish brown, with irregular purple patches giving a mottled effect,
which is attributed to irregular distribution of hematite. Both types are
interbedded with the sea-green and unfading-green slates but are less
susceptible to color changes than are the sea-green varieties.

Mill-stock Slates. — Certain purple and green slates having poor cleav-
age are used for various milled products, such as floor tile, vats, mantles,
baseboards, sills, steps, and to a small extent billiard-table tops, sanitary
slabs, and blackboards. Some purple slates are well-adapted for elec-
trical uses. Most of the slate used for milling purposes is obtained in
the northern district, near Fair Haven, Vt.

Red Slates. — Red slates associated with bright green varieties of
Ordovician age are found in Washington County, N. Y., near Granville.
The red color is due to abundant hematite. These slates occur in beds

SLATE 243

10 to 25 feet thick, and are used for granules and to a limited extent for
roofing.

Flagging and Building Stone. — Slate for copings, flagging, terraces,
ornamental walkways, and walls made entirely of slate or in combination
with other stones is produced in increasing quantities, particularly in
Washington County, N. Y. Very attractive sidewalks and porch floors
are made by fitting together flagstones of various sizes, shapes, and
colors.

Granules and Slate Flour. — Granules for the manufacture of prepared
roofing are made of both red and green slate at Granville, Middle Gran-
ville, Poultney, and Hampton. Slate is also ground to a fine powder
and sold as a filler for roofing mastic, paint, road asphalt, and various
other products.

General Distribution of Quarries and Mills. — Aside from granules,
flour, and slate for floors, walks, and walls the product of Washington
County, N. Y., is roofing slate. Many slates are of the thick, heavy
types known as architectural grades. Their rough texture and attrac-
tive, variegated colors adapt them for ornamental roofing material. A
few large companies have quarries near Granville and Middle Granville,
and many small quarry operators sell their products to them.

In the southern slate district of Vermont, which extends from Poult-
ney to West Pawlet, the chief product is roofing slate. Numerous
quarries are operated throughout this district and produce slates in a
wide variety of color combinations. Granules are also manufactured,
chiefly from green slates. In the northern district of Vermont, near
Poultney, Fair Haven, and Hydeville both roofing and mill stock are
produced. Several slate-finishing mills are operated, particularly in and
near Fair Haven. Structural, electrical, and roofing slates are important
products of this territory.

It may be observed from the above descriptions that Vermont and
New York produce slates in an attractive variety of colors particularly
well-adapted for roofing high-class residences and larger structures.
The heavy architectural grades are sold widely for ornamental roofs.
With proper color blending and graduation of size they produce effects
unsurpassed in attractiveness by any other roofing material. More
than 20 companies quarry slate in New York and more than 50 companies
in Vermont.

Pennsylvania. Lehigh District. General Features. — The Lehigh dis-
trict comprises Lehigh and Northampton Counties, Pa., and Sussex
County, N.J. The Pennsylvania slates occur in a strip 2 to 4 miles wide
on the south side of Blue Mountain, extending from Delaware Water Gap
on the Delaware River southwest to a point 4 miles west of Lehigh
Gap on the Lehigh River — about 32 miles. Quarries centered chiefly
around Bangor, Pen Argyl, Windgap, and Slatington constitute the most

244 THE STONE INDUSTRIES

productive slate area in the United States. The Sussex County (N. J.)
deposit, extending from Newton and Lafayette to the Delaware River, is
regarded as an eastward continuation of the Pennsylvania beds.

Slate produced in Pennsylvania in 1929 was valued at $4,798,200, or
about 42.7 per cent of the value of total production in the United States.
Production in 1930 was valued at $3,634,258, in 1931 at $2,791,752, and in
1937 at $2,735,744. A small part of the Pennsylvania production was
obtained from the Peach Bottom district, which is considered in a sub-
sequent section of this chapter. Roofing and mill stock are both pro-
duced extensively, and there is a small production of granules and slate
flour.

Geology. — A Cambrian and Ordovician dolomite and limestone plain
3 to 6 miles wide extends north and northeast from Easton, Pa., following
the general direction of the Delaware River as far as Belvidere. The
upper member, the Jacksonburg limestone, provides the well-known
cement rock of the Lehigh Valley. The limestone dips northwest, and
overlying it is the Martinsburg formation, which includes the slate beds.
At the southeast the shales and slates are in contact with the underlying
limestone and at the northwest dip under the Silurian conglomerate and
sandstone of Blue Mountain. The slate belt is 1,600 to 6,000 feet wide,
but only a few hundred feet are of commercial quality.

The slate formation consists of two lithologically different rock types.
The lower section, known as the "hard-vein" belt is made up of hard
closely bedded slates interbedded in places with sandstone. It occurs
farthest south passing through Belfast and Chapman Quarries. Above
it are beds of nearly pure sandstone, and higher still, a second type of
slate, which is soft and thick-bedded, with occasional sandy layers.
The upper section constitutes the "soft-vein" belt, which extends from
East Bangor through Bangor, Pen Argyl, Windgap, Danielsville, and
Slatington to Slatedale. From the structural relations it is evident that
the soft-vein slate everywhere occurs nearest the mountain.

The slate beds consist of a succession of close folds generally over-
turned northward so that their axial planes have a general southerly dip.
Folds are easily recognized by the curve of the ribbon. The slaty
cleavage dips southward at various angles, usually ranging from 5 to 20°,
and therefore intersects the ribbon at a high angle.

Varieties and Uses. Hard-vein Slate. — "Hard-vein" slate, as the
name implies, is relatively hard compared with the overlying beds. It is
used almost exclusively for roofing, walks, and masonry walls, as it is too
hard for milling. The rock is blue-gray, with somewhat darker carbon-
aceous beds. The more siliceous beds have a faintly silvery sheen.
Ribbons, consisting mostly of siliceous minerals highly resistant to
weathering, are numerous and closely spaced. They scarcely deflect
the cleavage, which is remarkably well-developed.

SLATE 245

CHAPMAN QUARRIES DISTRICT. — The most productivG district in the
hard-vein belt is at Chapman Quarries station on the Lehigh & New
England Railway. Quarrying began in this district about 1860.
Numerous openings have been made, but only two or three of the
largest have been quarried actively during recent years. The slate beds
in this area are folded and contorted, synclines and anticlines appearing
on quarry walls. The slaty cleavage, however, is remarkably constant,
generally ranging from 10 to 20° in a southerly direction. The principal
joints, which strike about N.60°E., are nearly vertical and form many
of the smooth faces seen on quarry walls. The grain is vertical and
strikes N.37°-53°W. While variations occur in different quarries the
general structure is much the same throughout the district. For many
years the larger quarries have continuously produced large quantities of
roofing slate. Heavy, rough-textured architectural slates are produced
in increasing quantities, and heavy flagging and grave vaults are made in
limited amounts.

BELFAST-EDELMAN DISTRICT. — Typical hard-vein slate of this area
lies within a radius of 23-^ miles of Edelman on the Delaware, Lackawanna,
& Western Railway. Only two quarries have been active recently, one
at Edelman and one at Belfast. In the Edelman quarry major joints
strike in a general northeasterly direction and are quite regular. Slaty
cleavage dipping about 10°S. cuts across the intensely folded beds. A
vertical grain trends about N.50°W. In the Belfast quarry the cleavage
dips east at angles of 5 to 22°, while the grain trends about N.40°W. and
is vertical. Roofing slate is the main product.

Soft-vein Slate. — The upper soft-vein member of the Martinsburg
formation consists of thick beds of light to dark bluish gray slate alter-
nating with thinner, almost black beds (ribbons). The wider ribbon-free
bands are known as "big beds"; they are particularly prized, as they
provide clear stock for blackboards and other of the higher-priced
products. Ribbons, which consist of thin carbonaceous beds, have an
important bearing on the value of slate, for most of them disintegrate
upon exposure a little more rapidly than the main body. For this reason
ribboned slate is not favored for the most enduring uses, though some of
it will give good service for 50 or more years. Because of their carbon
content ribbons are not good electrical insulators and therefore must be
avoided in the manufacture of switchboards and panels. For certain
exposed uses they detract from appearance, but as they do not affect
strength greatly, ribbon slate is widely used for many structural applica-
tions, such as steps, risers, baseboard, wainscoting, etc. Its easy
workability makes soft-vein slate particularly desirable mill stock.

"Hard rolls" is a name given to the sandy portions of beds which are
usually discarded, partly because they dull tools rapidly and are therefore
worked with difficulty and partly because the cleavage is inclined to be

246 THE STONE INDUSTRIES

curved or irregular. Siliceous knots, which are present in places, affect
the workability of the slate and cause uneven cleavage.

In the eastern or Bangor-Pen Argyl part of this region, the soft-vein
member of the Martinsburg formation may be separated into two parts —
the lower or Bangor beds and the upper or Pen Argyl beds. The former
extend from East Bangor through Bangor and thence southwestward,
passing from }^ to l^z miles south of Pen Argyl. The upper beds pass
through the southern part of the town of Pen Argyl and through West
Pen Argyl and Windgap. It is customary in the Pen Argyl and Bangor
districts to recognize certain subdivisions called "runs," which include the
several beds of slate exposed in a quarry or group of quarries. Generally
accepted names are applied to the more important runs, and the slate in
some instances is well-known to the trade by the name of the run from
which it is obtained. In general, the slate of any particular run is fairly
constant in quality from one quarry to another, although variations occur.

BANGOR DISTRICT. — The lower beds of soft-vein slate are slightly
harder than the upper, and ribbons are somewhat closer together.
Beginning at the top of the Bangor beds, the following runs generally are
recognized: North Bangor No. 3, North Bangor No. 2, North Bangor,
Bangor Union, Old Bangor, and Grand Central. Each is subdivided into
certain characteristic beds on the basis of thickness, ribbon, and color.
Seven or eight companies operate quarries near Bangor and East Bangor,
where more than 30 quarries are or have been active. The main product
is roofing slate which has won a high reputation through many years of
satisfactory service. Some beds are suitable for mill stock, and several
large mills are operated. Certain thin beds intermediate in color between
the carbonaceous black of the ribbons and the light gray of the big beds
are used for school slates.

PEN ARGYL AND WINDGAP DISTRICT. — The Upper soft-vcin slates that
extend southwest from Pen Argyl are grouped into well-recognized runs
in the same manner as those at Bangor. Beginning with the topmost
beds the following runs appear in succession: Pennsylvania, United
States, Diamond, Albion, Acme, and Phoenix. The runs are not in
direct contact with each other but are separated by intervening beds
75 to 280 feet thick, consisting of unworkable slaty rock. Each run is
made up of a series of individual beds; the Albion run, for example,
consists of 12 beds with an aggregate thickness of 184 feet; some are big
beds, some ribboned slate, and others unworkable rock. The Albion
"gray bed" is of exceptionally high quality.

Eight or 10 companies operate quarries in and about Pen Argyl.
The largest and deepest open-pit slate quarries in the country are in this
territory; a maximum depth of 725 feet has been attained, and depths of
400 to 500 feet are not uncommon. Deep quarrying is not entirely a
matter of choice; it is influenced by rock structures. Beds dip at very

SLATE

247

steep angles and in places are almost vertical. As property lines or heavy
overburden in many places restricts extension of quarries along the strike
and as beds are of limited thickness, a great volume of production can be
attained only by following the beds to greater and greater depths.

Rock structures are favorable for quarrying. Slaty cleavage gener-
ally dips south at a low angle, and quarry floors are maintained parallel

L-HlS^iiliia^KSlgSi'KSS*

Fig. 42. — View from the bottom of a ^late quarry 450 feet deep at Pen Argyl, Pa.

of I ngersoll-Rand Company.)

{Courtesy

to it. Open seams and loose ribbons provide smooth, uniform quarry
walls in places.

Figure 42 illustrates a deep quarry in the Pen Argyl district. The
curved wall at the right resulted from the presence of a loose ribbon.

In 1929 five companies were operating near Windgap about 23^^ miles
southwest of Pen Argyl. The same beds as at Pen Argyl are present; and

248 THE STONE INDUSTRIES

conditions are similar, although each quarry has its own peculiar
structures.

Both roofing and mill stock are obtained from most of the quarries
throughout the Pen Argyl-Windgap district, and large, well-equipped
mills are associated with the quarries. Durable, unfading slates with
straight, easy cleavage are used for high-grade roofing material; rough
splitting slate and mill ends for heavy architectural roofing-slates; big
beds for blackboards and large slabs of clear structural slate; smaller
beds of high dielectric strength for panels and switchboards ; and ribboned
beds for various structural and sanitary applications. Granules and
slate flour are manufactured to a limited extent.

SLATiNGTON DISTRICT. — A westward extension of the soft-vein slate
beds has been quarried extensively in western Northampton County near
Berlinsville and across the Lehigh River in Lehigh County at Slatington,
Emerald, and Slatedale. The quarries near Slatington occupy an area
of about 3 square miles along Trout Creek and its tributaries. As in the
eastern Northampton County district, quarrymen give special names
to the commercial beds. Following the beds dow^nward — that is, from
north to south the following are recognized: Columbia, Manhattan,
Locke, Star, Keystone, Mammoth, Big Franklin, Little Franklin, Wash-
ington, Trout Creek, Blue Mountain, Saegersville, and Peach Bottom.

The "Franklin big bed" and "Washington big bed," as they are
sometimes termed, are the most widely known, as they provide clear
stock of high quality in large sizes. Some of the beds mentioned may be
duplications, for the folding is close, and the same bed could easily
reappear several times. Complete anticlines or synclines are observable
on some quarry walls, as the folding in this district is around axial planes
that stand more nearly vertical than at Bangor and Pen Argyl and have
the effect of repeating the outcrop of individual beds. The curvature
is plainly marked by ribbons. Slaty cleavage is quite steep, in many
places reaching 60 to 75°, though in some quarries it may be as low as
35°. Curved cleavage has been noted in some beds. The grain is
nearly vertical and at right angles to the cleavage. Joints or "headers"
dip at various angles. The rock is dark bluish gray, and most of it splits
easily. About 10 companies were active in the district in 1930. A great
many quarries have been worked, some of them to depths of 300 or more
feet, but most of them are now abandoned. Slate is being mined locally,
in addition to the usual quarry operations. Both roofing and mill stock
are produced by all the companies.

New Jersey. — An eastward extension of the Pennsylvania slate beds
crosses the Delaware River and extends into Sussex County, N. J., as far
as Lafayette and Newton. The deposit is regarded as a continuation of
the hard-vein slate occurring at Chapman Quarries and Belfast. Near
Lafayette, where commercial development has taken place, the beds dip

SLATE 249

about 18° northwest, while the slaty cleavage dips about 19° southeast.
The grain is vertical and at right angles to the strike of the beds. The
slate is blue-gray and intersected by numerous ribbons at 1- to 15-inch
intervals. Like the hard- vein ribbons of Pennsylvania, they resist
weathering.

For a number of years before 1918 roofing slate was produced from
a quarry about 11^ miles north of Lafayette. The quarry was reopened
in 1922 and again in 1928. Slate of high tensile strength, low porosity,
and attractive color is obtainable in this district, but economical operation
evidently has not yet been perfected, for activity ceased again in 1930.

Pennsylvania-Maryland. Peach Bottom District. — The slate belt of
the Peach Bottom district is one-fifth to one-half mile wide, extending
from about 1 mile northeast of the Susquehanna River in Fulton town-
ship, Lancaster County, Pa., southwest across the river, across Peach
Bottom township, York County, and continuing about 3 miles in Cardiff
township, Harford County, Md. Its total length is about 10 miles. For-
merly about 1}4 miles were beneath the Susquehanna River, but since
the Conowingo Dam was completed a larger part of it is submerged.
Quarries are situated near Delta, Pa., and Cardiff, Md.

The slate, bordered by schist, is regarded as of pre-Cambrian age and
overlies older gneisses and serpentine. Three parallel belts 75 to 120 feet
thick extend northeast-southwest, but their structural relations are
obscure. Slaty cleavage is uniformly vertical or dips at a steep angle.
One or more nearly horizontal joints pitching gently southward usually
are present 40 to 60 feet below the surface and known locally as "big flat
joints." They include 2 to 3 feet of crushed slate, the fracturing of which
has evidently resulted from secondary crustal movement. Commercial
slate occurs only below this joint. Other joints intersect the slate, some
being vertical and others dipping at various angles. Inclined joints,
with quartz veins and lenses, cause much waste. The grain dips 20 to 50°
northeast.

As recorded on page 237, the first slate quarry opened in America was
in the Peach Bottom district, and slate therefrom used on seven successive
roofs over a period of nearly 200 years is still in excellent condition.
Although Peach Bottom slate generally is recognized as of superior
quality, the industry has never flourished. Lack of activity is due to
unfavorable quarry conditions, which are discussed in a subsequent
section on quarry methods in the various districts.

Peach Bottom slate is dark bluish gray, with a lustrous cleavage
surface. It contains graphite, magnetite, and a little pyrite but is
notably free of carbonate. An unusual feature is the presence of numer-
ous small crystals of andalusite. The main product is roofing slate, which
has an excellent reputation. At times a small amount of structural
slate is made. Only two companies have produced during recent years.

250 THE STONE INDUSTRIES

Two large mills, one in Maryland and one in Pennsylvania, produce
granules and slate flour.

Virginia. Buckingham and Fluvanna Counties. — Slate extends from
Fluvanna County across the James River and southward over 5 miles.
From fossils found in the beds the rock is identified as of Ordovician age.
The slate occupies a zone about two fifths mile wide along Hunts Creek, a
southern tributary of Slate River. At Penlan it strikes N.30°E., at
Arvonia N.35°E., and on the north side of the James River 3}^ miles
north-northeast of Arvonia N.20°E. The best commercial slate occurs
near Arvonia in a belt 200 to 250 feet wide and about 1 mile long. To the
south of this area the slate is of good quality, but the belt becomes too
narrow for profitable mining; to the north, while the belt becomes wider,
the slate is poorer in quality and splits with greater difficulty.

Bedding dips southeast at steep angles of 80 to 85°. Slaty cleavage
parallels bedding. Vertical dip joints strike about northwest; other
joints run northeast and in diagonal directions. There are also gently
undulating "flat joints" which the grain parallels. Closed seams or
planes of weakness, known locally as "post," cross the deposit at 20- to
60-foot intervals and serve as headings for the benches. The post runs
diagonally, causing much waste in places. A diabase dike 7 feet across
was uncovered in opening a new quarry in 1930.

Nature has provided a very interesting index or guide to the best
commercial slates. A certain easily recognized bed serves as a reliable
marker in locating workable beds. This indicator bed is about 20 feet
wide and consists of characteristically spotted or pitted rock. It occurs
on the western side of the belt, and good slate always begins about
20 feet east of this bed.

Buckingham slate is very dark gray or slightly greenish, with a
lustrous surface. It contains a little graphite, magnetite, and pyrite
but is notably free of carbonate. It splits with difficulty, with a rough
surface, which is an asset according to modern architectural demands for
variegated texture. Virginia slate is so hard that channeling machines
can not be used, and quarrying is done by drilling and blasting. As
timed by the writer, a pneumatic drill bit 1 inch in diameter sinks at a
rate of only 2 inches a minute. Except for small quantities used locally
for monuments and a small but increasing amount for walks and terraces
the entire production is roofing slate. It is very durable and has a
splendid reputation. Slates from the roof of the McGuire residence in
Alexandria, Va., which was built in 1820, show no discoloration or sign of
deterioration. Three large companies were operating quarries in 1931.
The largest excavations are 500 to 600 feet long, 250 feet wide, and 200 to
225 feet deep.

Albemarle County. — The slate outcrop of Albemarle County lies east
of the Blue Ridge and 10 to 12 miles west of the Buckingham County

SLATE 251

belt. Quarries have been opened at Esmont on Ballinger Creek, a small
tributary of James River. The rock is intensely folded into a series of
synelines and anticlines. Slaty cleavage dips northeast at an angle of
70° to 80°. Discontinuous vertical joints strike N.58°W. and are spaced
2 to 10 feet apart. Close, irregular jointing causes much waste in the
upper levels. Both black and green slates occur, and the same beds
appear repeatedly on account of close folding. One opening has been
worked to a depth of about 200 feet. The slate is soft enough to permit
channeling machines to be used in the quarry and circular saws in the
mill. Both roofing slate and granules are produced.

During recent years roofing slate of good quality has been produced
at Monticello, but no details of structure have been obtained.

States of Minor Importance. — The following States have been inter-
mittent producers of slate on a small scale.

Arkansas. — The slate area of Arkansas extends about 100 miles west
from Little Rock nearly to Mena and has an average width of 15 miles.
The principal developments are near Norman and Slatington in Mont-
gomery County. The rock is compressed closely in overturned pitching
folds. In some places cleavage parallels bedding; in others it is oblique.
Both red and green sla.tes are obtainable, and near Mena, Polk County,
greenish gray and black slates occur. Many attempts have been made to
develop the Arkansas deposits, but none has been successful on account
of the distance from markets, high freight rates, and large proportion of
waste. Mill stock was produced years ago, but recent production has
been confined to a small amount of flagging for walks.

California. — Between 1889 and 1915, when activity practically
ceased, Eldorado County, Calif., produced considerable roofing slate,
attaining a maximum of 10,000 squares a year in 1903 and 1906. Quarry-
ing was conducted most actively near Kelsey. The slate which is of
Jurassic age is bordered by a large area of diabase. The bedding is
marked by numerous ribbons, which are generally within 10° of the plane
of slaty cleavage, the latter being practically vertical with a N.25°W.
strike. The ribbons are not of marketable quality. A series of joints
parallels the grain, which strikes N.55°E. and dips 70 to 80 northwest.
The rock is dark gray and resembles Pennsylvania slate in general
appearance. A 6-mile aerial tramway was employed to carry the product
to the railroad near Placerville. The Chili Bar quarry about 3 miles
north of Placerville has been worked intermittently for the production of
granules, and at times a similar product is produced in Tuolumne County.

Georgia. — The Rockmart formation of Polk County has been the most
productive slate belt of Georgia, yielding bluish gray roofing slate, with
some interruption, from 1880 to 1913, with a maximum output of 5,000
squares in 1894. The slate is of Ordovician age and is underlain with
limestone. Bedding strikes N.20°-40°E. and dips southeast about

252 THE STONE INDUSTRIES

20 to 25°. Slaty cleavage strikes with the bedding and dips 40 to 45°
southeast. Ribbons are spaced 2 to 5 feet apart in places, and joints are
15 to 18 feet apart. Decline of the industry is attributed to increasing
cost and unsystematic development.

A second slate district of Georgia is in the Conasauga formation
of Cambrian age. The best slate, which is greenish gray, occurs south
of Fair Mount, Bartow County. The beds are greatly folded and
contorted, with cleavage dipping 9 to 45°. A small amount of roofing
slate was made prior to 1913, but recent production has been confined to
green granules and slate flour.

Michigan. — A large deposit of black slate occurs at Arvon, Baraga
County, close to water transportation. More than 50,000 squares of
roofing slate were made before 1881, when the quarry was last worked.
According to report the slate is of good quality, but the industry failed
because of mismanagement.

Tennessee. — Purplish, greenish, and black slates, probably of Cam-
brian age, occur in Monroe County. Green slate has been quarried to
some extent near Tellico Plains for granule manufacture, but operations
were discontinued in 1928, and the plant was moved to Fair Mount, Ga.

Utah. — Green and purple slates occur in Slate Canyon about 2 miles
southeast of Provo station. Purple slates are more abundant and have
better cleavage than the green. Granules were produced in a small way
prior to 1922.

GENERAL PLAN OF QUARRYING

The economical development of deposits involves many complex
problems, because slate, having resulted from intense regional meta-
morphism, usually occurs in folded or steeply inclined strata. As pointed
out in the discussion of the origin of slate, the rock consisted originally
of clay deposited in horizontal beds on the sea floor. Materials forming
each distinct original bed were deposited under fairly similar conditions
and were uniform over wide areas. No matter how intense subsequent
metamorphism may have been, changes were usually the same within the
boundaries of each bed, and therefore slate as it appears today shows
remarkably constant quality throughout the extent of each bed.
Changes in thickness may occur as a result of folding, but from charac-
teristic qualities certain well-defined beds may be recognized at points
miles apart. Therefore, if high-quality slate is found in a certain bed
an operator plans his quarry to follow this bed. Knowledge of geological
structure is usually advantageous, as, for example, in regions where close
folding brings a desirable bed to the surface in a succession of outcrops,
where a pitching axis of a fold depresses a bed laterally below the limit of
economic recovery, or where a fault carries a bed beyond the boundaries
of a quarry.

SLATE 253

The plan of a quarry is governed chiefly by geologic structures. In
Northampton County, Pa., beds are marked clearly by ribbons and thus
are easy to trace. Bedding dips at steep angles, ranging from 70° to
vertical. Following desirable beds under such conditions carries quarries
down 500 to 700 feet. Such quarries may be worked for years, with
little expense for removal of overburden but with some attendant incon-
venience in access and hoisting. As the slaty cleavage is nearly horizontal
or dips at low angles quarry walls are very strong, with no apparent danger
of bulging or collapse even at the greatest depths to which quarries are
now worked.

In Maine the beds are narrow and vertical, and the cleavage is also
vertical, a condition which makes walls weak and in constant danger of
collapsing if open pits are sunk 200 feet or more. The necessity for deep
mining, combined with the inherent weakness in the walls, led to the
ingenious method of driving deep shafts with lateral tunnels and removing
rock by overhead stoping. Slate in the Peach Bottom district of Penn-
sylvania and Maryland likewise has vertical cleavage, but through lack
of foresight the weak walls were so overburdened with piles of waste that
very expensive slides resulted.

In Buckingham County, Va., bedding and cleavage stand at angles
approaching vertical, but cleavage is less perfect than in Pennsylvania or
Maine, and the effects of freezing and thawing are less severe. The
beds are thick enough to permit wide openings, and quarrying is not
conducted at excessive depths.

In the New York- Vermont area bedding dips at an average angle of
40 or 45°, ranging in different quarries from 15 to 60°. This condition
necessitates wide, comparatively shallow quarrying, for with vertical
descent a pit may pass entirely through the desirable beds. Further
development then demands extension along the strike. Extension of a
pit down the dip of beds requires removal of an increasingly heavy
overburden. Where beds are inclined moderately, underground methods
have been followed in a few quarries in Vermont and near Slatington, Pa.

Steeply inclined open joints and "loose ribbons" are structures that
demand careful attention, as they may endanger operations through slides
of rock masses left without support. Several quarries have been closed
because of such slides. A wise operator plans his quarry as a permanent
industry and at the outset maps a plan that will permit untrammeled
development indefinitely. Lack of capital has been the chief cause of
inadequate development of many slate quarries.

QUARRY OPERATIONS

Stripping. — Stripping methods are described in some detail in a
previous chapter. Where quarries are carried to great depths or where

254 THE STONE INDUSTRIES

underground operations are followed no stripping may be required for
10 to 20 years. It may become necessary at more frequent intervals in
regions where quarries are comparatively wide and shallow. A heavy
overburden of soil and decayed rock usually is handled by power shovels.
Removal of overburden to an insufficient distance has often necessitated
handling waste material a second time when workings are enlarged.
More progressive quarrymen transport overburden and waste far enough
to permit development for many years without rehandling.

Drilling. — Compressed-air, nonreciprocating, automatic rotation,
hollow-steel hammer drills are the most popular. In a few quarries
where no air compressor has been provided steam tripod drills are used.
Churn drills are employed occasionally where there is a depth of 20 to
50 feet of waste rock that requires heavy blasting for removal. Soft-vein
Pennsylvania slate may be drilled rapidly. A maximum of 240 feet of
drill hole per man during an eight-hour shift has been noted. The hard-
vein slate of Pennsylvania and the Virginia slate are drilled much more
slowly.

To avoid damage to good slate, drilling in the adjacent country rock
is sometimes necessary; and if such rock is highly sihceous, as in the
Maine deposits, drilling may be much slower than in pure slate.

Blasting. — Commonly 10 to 40, or even 50, feet of slate nearest the
surface is altered by ages of weathering and must be removed as waste
before merchantable rock beneath can be reached. Dynamite blasts in
tripod, hammer, or churn-drill holes are used to shatter the upper levels,
but heavy blasting close to sound slate is carefully avoided. Waste
immediately above good slate is commonly channeled, and then fractured
for removal with light charges of black blasting powder.

Black blasting pow'der always is employed in commercial slate, as
the higher grade explosives cause much waste. Very small charges may
be utilized to advantage in making cross fractures or floor breaks,
but in best practice drill holes for such shots are only three eighths to
five eighths inch in diameter; and it is customary, even when firing with
electricity, to place a length of fuse in a hole merely to take up space and
distribute a small charge throughout the length of the hole. Shots may
be fired with a fuse or by electricity.

Before channeling machines were introduced blasting was the chief
method of separating the larger blocks, and the method persists in regions
where the slate is regarded as too hard for profitable channeling or for
sawing with wire. In such quarries walls are rough and irregular, blocks
are rarely uniform or rectangular, and waste usually is excessive.

Wedging. — Wedges, used for making floor breaks in deposits where
quarry floors parallel cleavage, may be driven in drill holes or in notches
cut in the face. For subdividing larger masses the plug-and-feather
method described in a previous chapter generally is used. Wedging is

SLATE 255

much easier, and a smoother surface is obtained parallel to the grain than
in other directions.

Channeling. — Channeling machines are described in the chapter on
limestone. Steam-driven machines were introduced first in the slate
industry about 1897 and were superseded by compressed-air machines.
Channeling machines have been used widely in working the softer slates,
notably in Pennsylvania and in Maine, but have not been favored in
the New York-Vermont, the Peach Bottom, or the Virginia districts.
Their employment in the softer slates marked a great in^provement over
previous methods, but wire saws have rendered them obsolete except in
Maine quarries.

A machine known as a "bar channeler" or bar drill, previously
described in the chapter on granite, preceded the modern channeling
machine. It was introduced in slate quarries about 1887, but the process
was so slow that it was not used widely; however, the method has per-
sisted in some quarries where the "stunning" effect of channeling
machines causes excessive waste.

Cutting with Wire Saws. Early History. — Wire saws have been
used for many years in Europe for making long, deep cuts in slate, marble,
limestone, and travertine quarries, but until recently have been used to a
very limited extent in America. The only early record of successful
use in the United States concerns one marble quarry in Colorado where
about 1913 they were employed to cut
out a mass of marble between two
deep, open quarries. Their use as
yard equipment for trimming blocks fig. 43.— Details of steel wire used as

of limestone and marble is not Un- ''"re saw in quarrying, natural size, a,
, , . ,. , . 1 cross section.

common, but wire saws did not become

an essential part of any quarrying industry in American until general
acceptance in the slate quarries of Pennsylvania during the summer
of 1928.

Equipment and Method. — A wire saw is simply an adaptation by
modern machinery of one of the most ancient stone-working methods.
The man of the Stone age shaped his stone implements by abrasion or
grinding; a wire saw utilizes this same principle, as it cuts stone from its
original bed by a simple abrasive process. Sawing is done with a three-
strand steel cable three sixteenths or one fourth inch in diameter and 800
to 2,400 feet long, running as an endless belt. Wire of the smaller size is
illustrated in figure 43. Splicing requires skill and care, as the splice
must be strong enough to withstand heavy tension and also be smooth
and without enlargements. Any projection of the wire beyond the
standard diameter would bind in a cut, and the wire would be broken.
An 8- to 10-foot lap usually is provided in making a splice. Driving
equipment ordinarily consists of a 10-horsepower electric motor with

256

THE STONE INDUSTRIES

worm-gear reduction running in oil. The driving pulley is one double-
grooved cast-iron sheave, or a pair of single-grooved sheaves, 40 inches in
diameter. The wire passes from one groove to the tension pulley, back
to the second groove, and from there to the quarry where the slate is cut.
It travels at about 15 feet a second.

The tension equipment is a suspended platform on which a weight of
800 to 2,000 pounds is placed to give necessary tension to the wire.
The tension carriage may travel back and forth on a track; thus, the
necessary adjustment in length of the wire can be made as the cut pro-
gresses. The arrangement of driving and tension equipment is shown in
figure 44, A. Orienting pulleys mounted on standards conduct the wire
from the driving equipment to the cutting unit in the quarry.

Driving,
Unii- '

Fig. 44. — Diagram of wire saw. A, driving end; B, cutting end.

Equipment in the quarry includes a pair of angle-steel standards 14 to
18 feet long, each having one or two sheaves at the top for receiving and
conducting the wire to a lower sheave which travels up or down by a rope-
pull or chain-pull worm gear. An upper guide pulley is shown in figure
45. The standards, which usually are set 60 to 100 feet apart, are placed
either on platforms over the edges of open benches or in holes 10 to 14
feet deep and large enough to accommodate the movable sheaves. By
lowering the guide pulleys the wire is brought in contact with the slate
and when fed with sand and water it makes a cut over the entire distance
between the standards. The arrangement of the cutting equipment is
shown in figure 44, B. The original equipment had guide pulleys 26
inches in diameter, but 18- or 20-inch sheaves are satisfactory. The
heavy tension maintained on the wire prevents excessive upward curvature
of the cutting strands, making it possible to complete a cut with the
center not more than a few inches higher than the ends.

SLATE

257

Holes or open benches must be provided to accommodate the standards
carrying the movable guide pulleys, which descend as the cut progresses.
Where there are open benches platforms are secured to the wall of the
bench and the standards erected on the platforms. Where there are no
open benches a core drill making a 36-inch circular hole is used for
sinking holes in the rock. It consists essentially of a rotating notched-
steel drum 30 to 42 inches high to which steel shot are supplied as abrasive.
When the drum has cut to its full depth, it is elevated and moved laterally
to permit removal of the core; then it is again put in place, and another
section is cut. This process is repeated until a hole of the desired depth is
obtained. Holes may be vertical or inclined at any angle up to 45°,

Fig. 45. — Wire-saw standard and guide pulley; sand box in foreground.

although cutting is slower in inclined holes. Inclination is commonly
desirable to follow the direction of the ribbon so that the standards may
be similarly inclined, making the cut parallel the ribbon and thus reducing
waste. Sand and water are supplied through V-shaped boxes, as shown in
figure 45. Sand is carried into the cut by a small stream of water from a
rubber hose entering the upper end of the sand box. For a cut 80 to
100 feet long three or four sand boxes are used, one being placed as close
as possible to the point at which the wire enters the rock.

A sand box developed in the Indiana limestone district, where wire
saws are used for scabbling, consists of two compartments. One is
kept nearly full of sand, and a stream of water supplied to it overflows
through a hole into the second compartment, which contains water only.
A thick sand slurry is drawn off continuously through a spigot and
thinned to any desired consistency by the addition of a stream of water
from the second compartment.

258 THE STONE INDUSTRIES

With a cut 80 feet long in the soft-vein slate of Pennsylvania the
cutting rate is approximately 4 inches an hour. At this rate the guide
pulleys should be fed downward about 1 inch every 15 minutes. A
convenient measure of cutting accomplishment is the surface area obtained
by multiplying the length of a cut by its depth. Thus, a cut 80 feet long
and 10 feet deep provides 800 square feet of surface. Figure 46 shows the
lower sheave and the wire where it emerges from the cut.

Introduction of Wire Sawing in Pennsylvania. — The United States
Bureau of Mines, the National Slate Association, and a group of Penn-

FiG. 46. — Wire saw at the point where it leaves the cut.

sylvania slate producers cooperated late in 1926 in the purchase of wire-
saw equipment from a Belgian firm. The first cuts were completed early
in 1927, and the unqualified success attained led to its almost immediate
and general acceptance by the slate industry of Northampton County, Pa.
Within two years about 30 wire saws and 12 core drills were operating,
and work with channeling machines was practically abandoned. Many
improvements in equipment were worked out, and several American firms
undertook its manufacture. Its successful use in slate has led to its
introduction in some limestone and sandstone districts.

Cost of Cutting. — Few details of the cost of operating with wire saws
have been obtained. The records of one company provide fairly com-
plete figures for 11 months' operation of wire saws and core drill, although

SLATE 259

the labor had to be estimated in part, as it was diverted to other work
at times. During the period covered, 44 wire-saw cuts totahng 22,753
square feet of surface were made. As nearly as can be determined the
total cost, including labor, power, repairs, supplies, and interest on the
investment, was 14.3 cents a square foot. In making these 44 cuts, 35
core-drill holes were required. To obtain a figure comparable with
channeling-machine costs, the core-drilling cost for each square foot of
surface sawed, amounting to 10.1 cents, must be added, making a total
cutting cost of 24.4 cents a square foot. This record dated from the
beginning of operation of both the wire saw and the core drill. The
efficiency of new equipment of this character is very poor during the first
few months of operation; therefore, the cost figures given probably are
much higher than those obtainable toward the end of the 11-month
period.

Channeling-machine costs in the same quarry have been calculated in
two ways: (1) The average daily footage over a 5-month period was
divided into the total cost of channeling-machine operation, estimated at
$20 a day, giving a figure of 64.5 cents a square foot; (2) the actual
channeling-machine cutting in square feet was taken for a 19-day period,
and the total labor, supplies, repairs, power, and interest on the invest-
ment for that period were charged to it. Th'is method gave a cost of 73.1
cents a square foot. For the same footage, therefore, channeling-machine
costs in this particular quarry are two and one-half to three times as high
as wire-saw costs, even when the latter probably are materially higher
than the average costs under normal operating conditions with skilled
workers. A rate obtained by another quarry company was 18.9 cents a
square foot for wire saws compared with 50 to 70 cents for channeling.
Several years' experience by many operators has confirmed the early
favorable estimates and has firmly established the conviction that the
wire saw is the most economical means of cutting slate.

Advantages of Cutting with Wire. — Aside from the definite saving in
cost of operation, as previously mentioned, the wire saw has other
advantages, the most important being reduction in waste of rock. Search
for a practical means of reducing excessive waste was, in fact, the incen-
tive for the original experiments, and results have fully justified the effort.
In making a cut a wire saw removes about one ninth as much material as a
channeling machine, because a cut made with wire is only about }i
inch wide, whereas the width of a channel cut is 2'^i to 23^^ inches.
Still more important is the fact that a channeling machine wastes much
rock on either side of a cut through shattering or "stunning," but the
wire, cutting by simple abrasion, leaves the rock unimpaired. Formerly
many subdivisions into blocks were made by wedging along the grain or
sculp, and much stone was wasted because of irregularities in fractures.
Separation of blocks with wire results in smoother, straighter surfaces

260 THE STONE INDUSTRIES

with less waste. In some quarries the grain and ribbon meet at obUque
angles, commonly approaching 60°. By channeling parallel with the
ribbon and wedging on the grain angular blocks are obtained, and in
cutting them to cubical mill stock many triangular masses of good slate
are wasted. It is customary now to make wire-saw cuts parallel to and
at right angles to ribbons, thus producing right-angled blocks that are
utilized for mill-stock products, with a saving in stone of 10 to 15 per
cent over former methods.

It is difficult to determine accurately the saving of rock accomplished by
using a wire saw. No records of the gross tonnage of rock quarried have
been kept under either former or present conditions. Various operators
estimate a saving of 30 to 50 per cent. Other advantages are speed of
operation, adaptability for continuous work during day and night until a
cut is completed, simplicity and ease of operation, and ability to make
inclined cuts conform with ribbons or other rock structures. Through
this new method of making primary cuts, with consequent reduction in
cost of operation and better utilization of raw materials, an annual saving
to the Pennsylvania slate industry of at least a quarter of a million dollars
has been accomplished. Quarry methods have been revolutionized, and
the industry has been established on a more secure basis. Other slate
regions have been slow in following this lead, but experiments are contem-
plated, and after fair trial and patient effort to overcome the difficulties
peculiar to each deposit, definite success will no doubt be attained.

Floor Breaks. — Methods of separating masses of slate at the quarry
floor vary greatly, depending upon the structure of the rock. In Penn-
sylvania and in the New York- Vermont district, where slaty cleavage
dips 5 to 45°, a quarry floor is maintained parallel with cleavage, and
floor breaks are easily made by splitting in that direction. Notches are
cut in the face and wedges driven into them, a process known as "driving
up splits." For separating exceptionally large masses drill holes are
projected at the floor of the bench to parallel the slaty cleavage, and a
fracture is made by means of small charges of black blasting powder.
Where slaty cleavage is vertical or nearly so floor breaks are made with
greater difficulty. Wherever possible horizontal seams are utilized.

Subdivision of Blocks. — In quarries where the floor parallels slaty
cleavage most primary blocks are too large to be hoisted to the surface.
Subdivision parallel to cleavage is accomplished by cutting notches in
the face of the bench in a line parallel to the cleavage and about 18 inches
or 2 feet from the top of the bench. A split is made by driving wedges
in the notches. Longitudinal vertical fractures are made by drilling and
wedging in the direction of the grain. Breaks across the grain are made
in the same manner, but drill holes must be closer together than where
they are parallel with the grain.

Block Raising. — After a block of the desired size is broken loose,
several men working simultaneously raise it by heavy bars with curved

SLATE 261

ends, used as levers. Freeing the rock is sometimes slow and difficult,
not only because of its weight but because of many interlocking corners
that must be actually broken. The most effective work results when
the energies of all the men are applied to their bars at exactly the same
moment. To obtain such unanimity a foreman frequently leads in a
sing-song rhyme, the men joining and keeping perfect time with their
crowbars. When a block is raised sufficiently a fragment of stone or a
wedge is dropped in the crack, the bars are placed in more advantageous
positions, and the process is continued until a hoist chain can be passed
under the block.

Hoisting. — Wooden derricks and compressed-air hoisting engines
are used in the Monson (Me.) district, but in practically all other districts
overhead cableway hoists are employed. Derricks may be advantageous
where a quarry is small or where, as in Maine, rock is removed from deep,
narrow quarries or from mine shafts. In most regions, however, pits
are so wide that a derrick boom can not reach all parts. For large pits
three to six parallel cableways are commonly required to serve properly
all parts of an excavation. The main cables range in diameter from 13^^
to 2)^^ inches, and the draw cables from 3^ to % inch. Most of them
are designed to carry 3 to 5 tons. Cable spans between supports (wooden
or structural steel masts) range from 500 to 1,800 feet. An advantage of
the cableway system at many quarries is its ability to convey waste rock
to the spoil bank by a single handling. Carriages equipped with auto-
matic dumping devices are widely used. Supplementary derricks are
used at some quarries for hoisting from pits or for yard service.

Signaling is usually done from a small house known as a "motion
shanty," which overhangs the brink of a pit in such a position that a
signal man has a clear view of the entire quarry floor. (See fig. 42.)
By means of an electric button for each cableway the signal man sends
to hoist engineers the messages which control all hoisting in the quarry.
At some quarries, particularly in the Vermont-New York district, a
board arm is used in place of electric devices. A board about 2)-^ feet
long and 5 or 6 inches wide, pivoted near one end, is attached to the roof
of the motion shanty and moved by a wire leading inside. The signal
code is based on the motions of the board.

The only means workmen have of entering or leaving the deeper
quarries is by cableway pan. A special signal is given when men rather
than materials are being conveyed, so that hoist engineers may exercise
special care. Hoisting accidents rarely occur.

QUARRY METHODS

Influence of Rock Structures. — The various processes by which
blocks of slate are separated from their original beds and hoisted to the
surface are covered in preceding paragraphs. There are many variations
in the manner in which these processes are combined, and differences in

262

THE STONE INDUSTRIES

method depend chiefly on rock structures. Ease of sphtting, direction
of slaty cleavage, direction of grain, position of joints, and dip of beds
influence the method. Slate can not be quarried successfully without
detailed knowledge of these physical properties, and familiarity with them
is gained only by actually working with the rock for some time. A
quarryman learns to know his rock, and this knowledge guides him in his
choice of methods. Quarry methods in their relation to rock structures
in each of the principal producing districts are covered in following pages.
Pen Argyl-Bangor District. — The slate area of eastern Northampton
County includes quarries in and about Windgap, Pen Argyl, Bangor,
North Bangor, and East Bangor. The output of this region exceeds that
of any other slate district in the United States.

Fig. 47. — Rock structures and quarry plan at a typical Pen Argyl, Pa., slate quarry,
a, direction of grain; b, ribbon; c, direction of dip of slaty cleavage; d, "loose ribbon;" r,
drainage sump; /, mass of slate ready for floor break; g, h, drill holes for "scallop" or
"sculp" blasting.

The strike of the rock is in general east-west but differs considerably
in different quarries. The structural feature that has greatest effect on
the quarry plan is the steep dip of beds, as indicated by ribbons. In
several deep quarries the ribbon is vertical or curves back and forth
from north to south in gentle, sweeping folds, usually at steep angles,
though in some quarries at East Bangor it dips only 30 to 40°. In
general, however, beds are so nearly vertical that the region is character-
ized by deep quarries with vertical or nearly vertical walls. Loose
ribbons and open joints may commonly be utilized to take the place of
channel or wire-saw cuts. Joints are generally spaced to permit removal
of large blocks.

A second structural feature which is decidedly favorable is a slaty
cleavage dipping at low angles, ranging from 5 to 30°. Quarry floors are
maintained parallel to cleavage; thus, blocks are easily separated, and
most of the floors are flat enough to be worked conveniently.

The positions of ribbon and grain govern the direction of cuts in a
quarry. In some quarries they intersect at nearly right angles; in others,
at angles of 70 or 80°. Before wire saws were introduced it was customary
to channel parallel to the ribbon and to make cross breaks parallel the
grain, either by wedging in drill holes or by using light charges of black

SLATE

263

Fig. 48. — Method of cutting a channel in
which standards are placed for transverse
cuts, a, core drill holes; b, wire saw cuts to
make channel; c, subsequent transverse wire
saw cuts.

blasting powder. This resulted in the production of angular blocks, as
indicated in figure 47, and in cutting such blocks into right-angled mill
stock the waste was excessive. Since wire saws have been used it is
customary to make cuts parallel to and at right angles to ribbons, produc-
ing rectangular blocks that may be cut advantageously into structural
products. However, for roofing manufacture angular blocks commonly
are used because there is less waste in reducing them to thin roofing than
in cutting them into slabs or cubical stock.

In opening up a new floor with wire saws core-drill holes are sunk in
the corners of the quarry, and from them wall cuts may be made in two
directions at right angles. Core
drilling is slow and expensive,
therefore operators usually plan
to utilize the holes to best advan-
tage. Where a series of parallel
cuts is to be made four holes may
be drilled, as shown diagram-
matically in figure 48. Wire-saw
cuts are made as indicated at b,
and the slate lying between them
is removed. A trench is thus
formed in which a standard may be
placed in any desired position for making the subsequent cuts, c.

A wire-saw cut is only one fourth inch wide, and blocks may jam in
relnoval if proper precautions are not taken when a new bench is opened.
To facilitate removal of key blocks cuts are not made parallel but con-
verge, as shown in figure 48. Binding is avoided by removing blocks first
at the wider end of the wedge-shaped mass. The cuts also are inclined
slightly toward each other, so that the mass of rock between is narrower
at the bottom than at the top; then, as wedges are driven and blocks
lifted the wider space in the upper levels provides ample room for any
necessary lateral movement.

The advantages to be gained from wire saws are now generally
recognized, and they are widely used to make numerous parallel cuts
whereby slate is obtained in smooth, rectangular blocks. Operators are
beginning to realize the advantage of numerous cuts; consequently, the
general appearance of quarries is markedly changed. Instead of curved,
irregularly broken bench walls, floors rise from bench to bench in regular
steps resembling those of a marble quarry. Wire-saw equipment in
process of making a cut 80 feet long is shown in the center of figure 49.
The walls at the upper left corner were cut with wires.

Slatington District. — The Slatington district, comprising the quarries
of Lehigh and eastern Northampton Counties, Pa., is characterized by a
series of close folds with east and west axes that pitch east. The ribbon

264

THE STONE INDUSTRIES

is distinct, and many loose ribbons or open bedding planes greatly facilitate
quarrying. Because of the close, repeated folding quarrying is complex,
and an operator must have a clear idea of the rock folds in and about his
quarry to develop the slate to best advantage. A succession of folds
may cause a bed of high-grade slate to reach or approach the surface in
several places. Probably in some quarries what has been regarded as a
succession of good beds is merely a single bed brought to the surface by
repeated folding. Some quarries are on synclines and others on anticlines ;
still others are worked on single limbs of large folds.

Fig. 49. — A Pennsylvania slate quarry, illustrating method of developing a new bench
with wire saws; standard holding guide pulleys in foreground. {Courtesy of I nger soil-Rand
Company.)

A remarkable feature of the Slatington district is the uniform dip of
slaty cleavage. With few exceptions, it dips 60 to 75° south, irrespective
of the folding of the beds. The sculp or grain is also remarkably constant,
crossing the rock generally a little east of south, and dipping to the east
at a steep angle, approximately 85 to 88° from the horizontal. Hence,
following the sculp tends slightly to undercut the east walls of quarries.

Joints and loose ribbons are utilized for headings and bench floors.
If no open seam or ribbon is available floor breaks must be made in the
hard-way direction, which gives rough, uneven floors. The downward
curvature of a high-grade big bed under a great thickness of waste rock

SLATE

265

has led to the development of underground methods. One quarry near
Berlinsville has quite extensive underground workings.

Hard -vein District. — Structures of the hard-vein slate at Chapman
Quarries and Belfast, Pa., are similar to those in the soft vein of eastern
Northampton County. Slaty cleavage dips 5 to 15°, and quarry floors
are maintained parallel with it. Wire saws are used successfully,
although the rate of sawing is somewhat slower than in the softer slates.
A vertical grain is utilized in making cross fractures.

Granville -Fair Haven District. — In Washington County, N. Y., and
Rutland County, Vt., the slates dip at angles approaching 45°. Quarries
are relatively shallow because the depth of overburden becomes very

Fig. 50. — Rock structures and method of separating blocks in a quarry near Fair
Haven, Vt. o, grain direction; b, open bedding planes; c, split holes; d, notches for wedging;
e, break on grain;/, break across grain; g, dip of beds and slaty cleavage.

heavy in following down the dip. In some workings near West Pawlet,
however, the beds dip steeply, and quarries are deep. Slaty cleavage is
at steeper angles than in Northampton County, Pa., ranging from 10 to
30°. Quarry floors parallel the cleavage and are inconveniently steep
in some quarries. Channeling machines are not used in this territory,
as it is claimed that the rock is too hard for successful operation. Vertical
joints are utilized wherever possible for walls and bench headings. If
joints are not available fractures are made with charges of black blasting
powder. Rock structures and methods in a typical quarry of this
district are shown in figure 50.

Open beds, as indicated at b, commonly occur at intervals of 5 to 7
feet and are thus spaced conveniently for bench floors. Cleavage par-
allels bedding. If a floor is tight, holes are drilled along the bed from the
open side, as shown at c, and very light charges of black blasting powder

266 THE STONE INDUSTRIES

are fired in them to jar the rock and free the bed. When the floor is free,
a break is made on the grain by blasting in holes drilled the full depth of
the bed. One hole is made for about each 15 feet of the desired break.
"Foot joints" or "headers" are commonly utihzed to form the third
free face, but if they are not available, blasting is used. Large masses
are thus set free, and further subdivision is made first by driving wedges
in notches cut in the face, as shown at d, and then by using plugs and
feathers in drill holes parallel to and across the grain, as shown at e and /.
In some quarries in the southern part of the slate area the dip of beds
and cleavage approaches 60 or 70°; consequently, underground methods
have been followed. Webs or elongated pillars of slate are left at intervals
to support the steep, overhanging roof.

Overhead cableway hoists are used almost universally. Roofing

slate is manufactured at the quarries,
although mills for structural and electrical
slate usually are situated at near-by towns.
Peach Bottom District. — Although Peach
Bottom slate has a nation-wide reputation
for high quality, in some respects quarry
conditions are unfavorable. In a number
of quarries steeply inclined open joints
have permitted unsupported masses of rock
to slide into the pits. The tendency toward
driff f» 'leThlrSpSl'Mon- wall collapse is increased through the pres-
son, Me. a, drift; ?>, 10-foot slate ence of a vertical cleavage which weakens
'if^bed^rVpefventaurms'; walls and makes them incapable of support-
/, horizontal roof seam; g, drill ing heavy loads. Channeling machines are
holes for blasting. ^^^ ^^^^^ p^^^j^ ^ecause the vertical

cleavage is unfavorable and partly because the rock is considered too
hard. Benches are worked to open joints wherever possible. If no
flat joints occur floor breaks must be made by blasting across the cleavage.
Monson District. — Conditions at Monson, Me., are similar to those
in the Peach Bottom area, except that the best beds are relatively thin.
Both bedding and slaty cleavage are vertical, and much of the highest-
grade slate is obtained from one 10-foot bed. Deep quarrying in narrow
opencuts was beset with many difficulties, owing to bulging or collapse of
the walls. Cross supports, consisting of steel I-beams and concrete, were
constructed at great expense in an effort to hold the walls apart, but at
depths beyond 300 feet they were inadequate. An overhead-stoping
system was then introduced and has been very successful. The first
step was to project drifts right and left at the old quarry floors about 300
feet below the surface. They were driven 80 to 100 feet along the slate
bed, and vertical wall seams and horizontal floor and roof seams were of
great assistance. The procedure when a drift is completed is shown

f J

0
0

9°

SLATE 267

in figure 51. At the northwest side of the drift, or at the left, as shown in
the figure, a 2-foot slate bed, c, is separated by a few inches of quartzite,
d, from the 10-foot slate bed, h. Good slate could be obtained from the
2-foot bed, but as the slate drills much more easily and rapidly than the
quartzite, holes are drilled in the narrow bed, which is largely destroyed
in quarrying. Drills are mounted on scaffolds and holes laid out on 16-
inch centers and staggered, as shown at g in the figure. The depth of
holes is governed by the position of the back seam, but it averages about
12 feet. The holes are loaded with light charges of black blasting
powder and fired singly, beginning at the lowest. They are staggered to
prevent the discharge of explosive in one hole from shattering the rock
surrounding the succeeding hole. The narrow band of quartzite serves
as a cushion and prevents shattering of good slate in the 10-foot bed. A
mass of stone is worked down in this way until an upper seam is reached,
as shown at / in the figure ; then a final shot is discharged in a vertical
hole drilled in the back corner at the southeast side to clear down all the
slate to the open seam. From the mass of stone thus thrown down all
good material is selected, hauled to the drift entrance by cable, and
lifted to the surface by derrick hoists. Waste slate is left on the floor,
and the heavy cost of removal is thereby saved. Thus, the floor is
constantly built up with waste; for ideal operation it should keep pace
with the upward progress of stoping from the roof. Waste is not suffi-
cient in volume to build up the floor as fast as the roof is elevated, and
additional rock is blasted from drift walls to keep it within easy reach of
the roof. The drift is gradually worked upward toward the surface.

The method proved so successful that one company put down a shaft
1,000 feet deep and drove lateral tunnels from its bottom. Thus, a
reserve of slate is provided for many years' constant mining. Advantages
of the stoping method are: (1) The great saving occasioned by leaving
waste rock in the pit; (2) reduction in hazard from roof falls, as the floor is
at all times only a short distance below the roof; (3) reduction in hazard
from fragments of falling rock during hoisting or from falls of rock from
walls or upper edge of excavation; (4) elimination of impediment to opera-
tion from snow, ice, or inclement weather; (5) absence of danger from
collapsing walls.

Where a series of many parallel slate beds is worked open-pit methods
are followed. Channeling machines are used, but they cut rather slowly
on "edge-grain" rock.

Arvonia District. — Slate structures of Buckingham County, Va., are
similar to those in the Peach Bottom and Monson districts, in that bedding
and slaty cleavage are nearly vertical, ranging from 80 to 85°. Open-pit
methods are employed, and some quarries reach a depth of 225 feet.
Walls are quite secure, with no apparent danger of collapse. Buckingham
slate is so hard that no successful means of cutting it has yet been found.

268 THE STONE INDUSTRIES

In opening a new floor a trench 6 to 10 feet wide and 12 feet deep is first
made, usually in a zone of defective rock, as the heavy blasting required
would destroy good slate. Benches are always terminated at closed
seams or "post," along which the rock breaks easily. From the bottom of
the trench horizontal holes are drilled about 12 feet deep, and about 12
feet back from the edge of the trench steeply inclined holes are sunk
parallel to the slaty cleavage. Vertical holes are drilled also along
the "post." Black blasting-powder charges are fired simultaneously
in all the holes, and thus a mass of slate is broken loose. A disadvan-
tage of the method is fracturing in three planes simultaneously, which
shatters the slate excessively. According to best quarry practice a
fracture should be made by blasting only when there are five free faces
instead of three.

YARD TRANSPORTATION

Slate blocks transported to quarry banks by cableways usually are
placed on small cars and conveyed to splitting sheds or mills for treat-
ment. For this haulage, gasoline locomotives are popular. Sometimes
finishing mills are located in towns several miles distant from quarries,
necessitating transportation by motor trucks or other means.

An important part of yard transportation is involved in the disposal
of waste rock. Tracks from quarry banks usually lead by a moderate to
steep incline over a waste heap, which gradually increases in height and
in lateral extent as cars loaded with waste are hauled by cable and
dumped at the end of the track. In some instances quarry waste is
conveyed directly by overhead cableways, and if an automatic trip is
provided no labor is required for disposal.

Transportation also involves conveyance of finished products to
railway sidings or storage yards. As roofing slates often are split at
shanties on high waste heaps the slates are conveyed down to the normal
ground level by cable cars. For this purpose long eight-wheel cars
commonly are used. In many places where transportation lines are not
immediately available teams and wagons or motor trucks are used for
both short and long hauls.

A unique method of transporting slate from quarry to railway is an
electrically driven aerial tramway 2 miles long at South Poultney, Vt.
It carries 400 buckets and has a capacity of about 200 squares a day.
Two men load and three unload the buckets.

MANUFACTURE OF ROOFING SLATE

The manufacture of roofing slate is the oldest branch of the industry,
and, strangely enough, the essential processes of splitting and trimming
are conducted in the same way as when the industry was in its infancy.
Many years ago a slate-splitting machine was invented and used success-

SLATE 269

fully in an experimental way, but never for commercial production.
This machine split the slate by rapid impact of a flexible steel blade.

Shanty Method. — What is known as the "shanty method" of making
slate dates back to the beginning of the industry and is still widely used.
Quarry blocks of suitable slate are conveyed directly to splitting shanties,
which usually are high on waste heaps. The shanties are only large
enough to accommodate two men — a splitter and a trimmer — and are
heated in winter by small coal stoves.

The first process is known as "block making," a reduction of large
masses to sizes suitable for splitting. Blocks are split to any desired
thickness by driving wedges in the direction of slaty cleavage. They are
then "scalloped" longitudinally in the grain direction by wedging in
plug holes.

Intimate knowledge of the physical properties of slate is essential in
breaking and splitting blocks properly. A skilled slate worker drives a
wedge or plug until a strain is placed on the rock; he then procures a
straight break by striking a blow with a wooden sledge at a particular
point on the rock ; he can thus within certain limits force a fracture where
desired. The slate is split on the grain into masses about 14 to 24 inches
wide, and these are then broken across.

Various methods are used to subdivide slate masses across the grain.
The corners may be notched with a chisel or with a small saw and a
smooth, even break obtained by striking one or two heavy blows with a
large wooden mallet. To cushion the blow and thus preserve the slate
from damage a thin flake of slate or a handful of fine slate rubbish
usually is placed on the surface of the rock where the mallet strikes.
Slates that break with difficulty may be sawed across with circular saws.

After they are broken across the cleavage the masses of slate are
split parallel to the cleavage with a hammer and special chisel known as a
"splitter"; the thicknesses thus produced are sufficient for eight slates
each. The thickness of a slab is always measured with the splitter.
Thus, if a thickness of %6 iiich is required for the finished slate, the
splitter blade is eight times ^e inch, or 1}^ inches wide; if the thickness is
to be increased slightly the blacksmith is instructed to make the splitters a
little wider.

Blocks are not allowed to dry out until finally made into roofing
slates, as they split with much greater ease if the quarry sap is not allowed
to evaporate. Maine slates are said to be an exception to this rule, as
they split readily when dry. Blocks are made in the yard and finished
blocks piled in the shanty. Here a slate splitter sits on a low seat with a
block of slate resting against his knee. His tools are a wide, flexible,
splitting chisel and wooden mallet. Blocks always are split in the center
until slates of finished thickness are obtained. Some slates are split
from the ends of the blocks and others from the sides. For tough-

270 THE STONE INDUSTRIES

splitting slate the chisel may be greased. A pneumatic chisel that has
been used successfully in Vermont is impelled by rapid vibrations on the
same principle as a pneumatic drill or stone-dressing tool.

A trimmer takes the slabs from a splitter and cuts them rectangular.
The trimming equipment most often used, particularly in Pennsylvania,
is a straight blade about 3 feet long, run by a foot treadle. The outer
end of the blade is attached to an overhead spring pole, so that the
blade strikes repeated blows when once set in motion by the treadle.
Another common type is a rotary trimmer which has a curved blade
similar to the cutting blade of a lawn mower. Most trimmers of this
type are run by foot treadles, though at some plants they are belt-driven
from a countershaft.

The steel gage bar on which slates rest for trimming has a series of
notches which serve as guides in trimming to standard sizes. A skilled
trimmer can determine very quickly the size to which each slate will
trim to best advantage. The following table shows the standard sizes,
in inches, of roofing slates carried in stock by most companies:

Slate Sizes for Sloping Roofs

10 X

14 X 9

18 X 12

10 X

14 X 10

20 X 10

10 X

14 X 12

20 X 11

12 X

16 X 8

20 X 12

12 X

16 X 9

20 X 14

12 X

16 X 10

22 X 11

12 X

16 X 12

22 X 12

12 X

18 X 9

22 X 14

14 X

18 X 10

24 X 12

14 X

18 X 11

24 X 14

Slate Sizes for Flat Roofs*

6 X

10 X 6

12 X 6

6 X

10 X 7

12 X 7

6 X

10 X 8

12 X 8

3 for ordinal

•y service usually are ^ie

inch thick.

For promen;

ordinary service they may be }'i to ?^ inch thick.

To facilitate handling roofing slates racks with a series of shelves
divided into compartments are provided within easy reach of the trimmer.
Slates are sorted according to size and quality as they are made, and a
section is reserved for each class. Once a day, either just before closing
time or early in the morning, the slates are loaded on cars and taken to the
piling yards. A typical roofing-slate piling yard is shown in figure 52.

Mill Method. — One efficiently planned roofing-slate mill has been
operating for many years near Poultney, Vt. About 1925 several com-
panies in Pennsylvania erected and equipped mills for the same purpose.
A plan of a typical mill is shown in figure 53. Blocks are brought into
the mill on cars and stored at c. The mills are equipped with overhead
traveling cranes or derrick hoists. Slate blocks are cut to desired

SLATE

271

lengths with circular saws. By using saws objectionable "ribbons" or
" hard ends " may be cut off, and thus many blocks which would be thrown
away by the old method may be used. A saw cut provides a smooth
surface, which makes splitting easier and also tends to conserve slate,
for it is straight, while the breaking method often results in crooked and
uneven fractures. One company has equipped its mill with a 60-inch
diamond saw for cross cutting blocks of "hard-vein" slate. It is claimed
that waste is reduced at least 15 per cent thereby, and mill production
per man is increased a like amount. In mills one blockmaker and
helper can provide blocks for two splitters. By the shanty method a
splitter spends part of his time making blocks, piling slates, or shoveling
rubbish; by the mill method he splits practically all the time. All

Fig. 52. — Typical roofing-slate piling yard with splitting shanties in background.

trimming machines in mills are power-driven; thus, the tiring operation
of a foot treadle is avoided. Also, finished slates are piled in portable
racks mounted on wheels. The filled racks are hauled to the storage
yard by gasoline locomotive, horse, or other means. Thus, arduous
rehandling of slate is avoided. Waste from both trimmer and splitter
falls down slides into cars on depressed tracks and is conveyed to a dump,
or it may be carried continuously with a belt conveyor.

"Architectural" Slates. — The preceding paragraphs on roofing slate
deal exclusively with standard types three sixteenths to one fourth inch
in thickness. Until recent years only smooth slates of uniform size and
color have been in demand, but modern architectural taste calls for
increasing quantities of rough-textured slates, graded in size and of vari-
able and mottled colors. Slates showing contrasting color effects are
obtained mainly in the New York- Vermont district, but many textural or
"architectural grades" are produced in other districts. Variations in

272

THE STONE INDUSTRIES

-I—

e
7

e
7
e
7
e
7
e

TFT

Fig. 53. — Plan of roofing slate mill, a, track for slate blocks
block storage; e, saw beds; /, boxes for waste; g, blockmakers; h,
belt conveyor for waste; I, track for portable slate rocks; m, track

; h, traveling crane; c, d,
splitters; z, trimmers; k,
for waste.

SLATE 273

sizes, colors, and surface finish produce rustic effects that are very attrac-
tive, particularly in large structures. The demand for slate of this type
has been advantageous to producers. No substitute materials have been
found that provide the rustic effects of the natural slates, and therefore
this branch of the industry has grown rapidly. Furthermore, large,
heavy slates, some of them 1 to 2 inches thick, may be manufactured
from beds where the material has too poor a cleavage for manufacture
into standard-grade roofing slate, and more complete utilization of quarry
rock is possible. Special types of powerful trimming machines are
employed to dress massive slates. The knives are constructed purposely
to make wavy, irregular outlines.

STORAGE OF ROOFING SLATE

Finished slates are piled on edge in storage yards, and each pile
comprises slates of the same size. They are placed in a nearly vertical
position and usually are stacked not more than three tiers high (see
figure 52). As a rule, slates are punched for nailing before shipment.
A punching machine, operated by a foot treadle or motor, punches two
holes simultaneously. The side uppermost in punching is placed down-
ward on the roof, for the punch makes an inverted conical hole, the
larger part of which provides a ready means of countersinking a nail
head. Slate too thick to punch and some thin slates on special orders
are drilled and countersunk, usually with motor-driven rotary drills.

THE ART OF ROOFING WITH SLATE

To endure for many years a slate roof must consist of high-grade
material free from cracks or other defects. The units must be of standard
thickness and proper manufacture, with the grain parallel to the long axis.
Part of the responsibility for a good roof rests however with the roofer,
for excellent-quality slate may make a leaky roof if improperly placed.
That any carpenter can lay slate is a common statement, and many roofs
are laid by inexperienced workmen, but they give much better service
when placed by men who specialize in such work. For example, in
placing slates most carpenters drive the nails "home," just as they would
in securing wooden shingles, with the result that if the sheeting dries
and shrinks the slates are cracked. A skilled slate roofer does not drive
the nail to its full depth, but allows the slate to hang loosely.

Another common error is due to mistaken economy or even dis-
honesty on the part of a roofer who to save slates may give a head lap less
than the regulation requirement of 3 inches. As a result the roof may
leak, not through any fault of the material, but because of improper
workmanship. The law in some States renders it illegal to place slate
with less than a 3-inch head lap. Nails and other metal work used in
conjunction with slate should be durable.

274 THE STONE INDUSTRIES

MANUFACTURE OF SCHOOL SLATES

Slate suitable for the manufacture of school slates is found in soft,
black beds free of all hard streaks or knots of flinty material. The
rough blocks are split in the same manner as roofing slates, but trimming
is done with small saws rotating at high speed. The shape of one type in
common use is shown in figure 54. When trimmed to size they are

delivered to school-slate factories. Here
the edges are first beveled; then the
slate is placed on edge between two
knives, and a descending bar forces it
down, so that the knives scrape off all
rough projections. A second pair of
knives gives a smoother surface. The
slates are then polished between sanded
drums, thoroughly washed in hot water,
and carried on a belt conveyor through
a heated chamber for drying before being
piled. They are then ready for framing.
Fig. 54.— Type of rotary saw used for gjates broken in framing are unframed

trimming school slates. n . ci i

and recut to smaller sizes, iseveral
million school slates are manufactured in the United States every year,
and about 90 per cent are exported.

MANUFACTURE OF MILL STOCK

The term "mill stock" includes all forms of structural slate, such as
steps, wainscoting, baseboard, lavatory enclosures, and mausoleum
crypts, as well as billiard tables, grave vaults, blackboards, and electrical
panels or switchboards. The chief processes within the mill are hoisting,
sawing, planing, edging or jointing, rubbing, and buffing or polishing.
Mills usually are close to quarries and are in the form of long closed
sheds. Slate blocks are brought from quarries on cars hauled by gasoline
locomotive or some other means. Derricks are provided for handling
blocks and waste, but some newer mills have overhead traveling cranes of
5- to 10-ton capacity.

Sawing. — Quarry blocks are measured and marked in accordance
with the products to which they will cut to best advantage. A marked
block is placed on a saw bed, which is propelled back and forth by a
pinion working in a rack of cogs. Different rates of travel are made
possible by a system of gears. The slow speed may be not more than
3 inches a minute ; when thinner or softer slate is cut a bed may travel 20
inches a minute or faster. The belt which drives the saw runs on a
cone of pulleys; thus different rates of rotation may be obtained, and the
desired speed is governed by the nature of a slate block. An average

SLATE 276

rate is six or seven revolutions a minute. Saws range from 24 to 48
inches in diameter and are about % inch thick. The teeth are so widened
that a saw makes a cut about ^i inch wide. Ordinarily the saw tooth is
part of the blade, but an inserted tooth saw is used where flint knots or
pyrite crystals are liable to break teeth. Some experimental work has
been done with tungsten carbide-tipped teeth, but such saws are not
yet used commercially.

Gang saws are employed to a limited extent in Vermont in slate
regarded too hard for circular saws. They are the same in principle as
gangs described in the chapter on limestone, except that the blades are
only about 6 feet long. Steel shot are used as abrasive.

Experiments are contemplated with the view of adapting wire saws
for reducing mill blocks.

Disposal of Sawed Blocks. — After sawing is completed the next step
in manufacture depends upon the purpose for which the slate is to be
used. When clear blackboard stock is obtained the block is hoisted
from the saw bed and leaned against a wooden or concrete pedestal.
With hammer and thin flexible steel chisels it is split into slabs about
one half inch thick. Slate with a straight split is in great demand, for if a
curved or twisted surface is obtained the finishing process is expensive,
as much slate must be worn away to reduce the surface to a perfectly
uniform plane. Finishing processes are described in later paragraphs.
For other forms of mill stock, sawed blocks are split to approximate
thicknesses desired and placed on planer beds.

Surface Finishing. — Planing is the first step in surface finishing.
The tool — a heavy blade set horizontally and adjustable laterally and
vertically — planes the surface of a block as it is carried back and forth on a
traveling bed. With each motion the tool is moved laterally until it has
passed over the entire surface. If all irregularities are not removed the
tool is set at a lower level and the block replaned. It is then turned over
so that the smooth surface rests on the bed, and the opposite side is
planed in the same manner, but special care must be taken to obtain the
desired thickness for the finished product. A block is not reduced to its
final thickness in a planer, for some allowance must be made for removing
slate during subsequent processes, such as rubbing or honing. Black-
boards are planed only when they are uneven or have a curved split.
For rougher forms of structural slate, such as grave vaults, planing gives
the final surface finish.

For a smoother finish slabs are placed on rubbing beds similar to those
used in marble and sandstone mills. They consist of cast-iron disks
12 or 14 feet in diameter which rotate in a horizontal plane with the slate
slabs resting on the upper surface. A stream of water is constantly
supplied, and sand is used as abrasive. A rubbing bed is not only used to
obtain a smooth surface but also to grind rectangular blocks to size. An

276 THE STONE INDUSTRIES

operator uses a gage and square and thus can turn out blocks true to
size and having right angles. A rubbing bed also is used for making
beveled edges on switchboards and other products, though often a coarse
file, pneumatic tool, or Carborundum wheel is used for this purpose.

Certain products, such as blackboards and switchboards, require a
much smoother finish than is obtainable on a rubbing bed. A fine polish
or honed finish may be obtained with a belt or drum sander, a buffer,
some other form of polishing machine, or by hand. A buffer, which is
most commonly used, consists of two movable arms; one attached to the
end of the other, holding a rotating buffer head. The latter is belt-
driven, with one belt for each arm, and the pulleys are so adjusted that
their axes coincide with the axes of rotation of the arms ; thus, the polishing
head may be moved about to any desired position without interfering in
any way with the movement of belts. The rotating head is fitted with a
set of six or seven blocks set in plaster of paris and consisting of polishing
materials made up in accordance with various formulas worked out by
mill operators. A stream of water is directed on the surface, and the
rotating head is moved back and forth until a fine polish is obtained. A
special type of multiple-head polishing machine, consisting of a series of
six rotating arms, each with a polishing block, has been devised to take
the place of a buffer. The circles overlap, and the arms are so adjusted
that blocks follow each other over the same ground with no interference.
A slab of slate to be polished is placed on a traveling bed which conveys it
back and forth beneath the rotating arms. In some mills blackboards are
finished by hand methods with steel scrapers and polishing blocks.

Through the use of drum sanders instead of rubbing beds and buffers a
noteworthy advance in surface finishing has been accomplished by a
Maine slate company. Paper-backed silica sandpaper is wound spirally
on drums, three drums are arranged in series, and slate slabs are passed
beneath them on a traveling rubber-covered bed. First, coarse grit is
used to bring down the surface to fair uniformity and smoothness, and for
finishing finer grits are used. A drum sander is several times faster than
a rubbing bed and may with further development also replace planers.

Carborundum machines are used widely to cut cove base and floor tile,
to cut bevels or grooves, to trim blackboards, and to recut slabs to smaller
sizes. The bed carrying the slate slab is stationary, and the rotating
wheel travels back and forth. The machine cuts rapidly and accurately
and leaves a very smooth surface.

Drilling Holes. — Electrical companies using switchboards commonly
drill them for wiring, but sometimes this is done at slate mills. Extreme
accuracy is demanded, as to both position of holes and workmanship.
One mill in Maine uses a spindle drill which can bore 16 holes at once.
The spindles that hold the drills are flexible and so may be adjusted to
position. A pattern or template is used through which the drills mark the

SLATE

277

slate block. The template is then removed, and the drills are guided
accurately by the depressions thus formed.

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Storage. — Blackboards, electrical slate, panels, steps, and other
structural forms usually are stored at the finishing end of the mill.
Racks are provided where all slabs may be placed on edge, for thus each
one is available when needed.

278

THE STONE INDUSTRIES

Flow Sheet of Slate Mills. — The machines in a mill should be so
arranged that the slate passes most directly from one to another, for much
time and labor are saved thereby. The normal order of operations in
slate manufacture is shown in the flow sheet, figure 55. A plan of a typi-
cal mill arranged for convenient operation is shown in figure 56. Slate
blocks are brought from the quarry into the mill on track a, track h being
used for removal of waste. Blocks are handled by derricks c, between the
tracks. Saws, d, are arranged down one side of the mill and planers, e,
down the other side. After the preliminary stages of sawing and planing,

I slabs are finished in the three wings,
I as shown at the left. Each wing

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has a rubbing bed /, near its en-
trance followed by a series of finish-
ing machines, such as Carborundum
bevelers, recutters, and polishing
machines, as shown at g and h.
Each wing may be devoted to a
particular product; for example, one
may be used for blackboards, one
for electrical slate, and a third for
structural slate. A railway siding
at the ends of the wings provides a
ready means of shipping mill prod-
ucts. An important feature of the
mill is the facility with which it
56.— Plan of a well-designed slate permits expansion. If increased

b, mill-car tracks; c, derricks; capacity is demanded it may be

!; /, rubbing beds; 0, «, . , ,.

Fig.
mill, a,

d, saws; c, planers; j, x^.^.^-..^. "— -, »'•-', i i j j i-

Carborundum machines, polishing machines; extended and one Or more addl-

i, space for storage and crating. tional wings added, as indicated by

the dotted lines in the figure, without interfering in any way with the
logical order of machine arrangement.

Marbleizing Slate. — For ornamental switchboards, mantels, and
certain other interior decorative products architectural taste sometimes
demands a finish other than the natural slate surface. Repeated painting
and baking to simulate verde antique, bloodstone, or well-known mar-
bles, is known as "marbleizing." The following is a typical process.
The slabs first are painted black, then baked several hours in a cham-
ber heated to 175°F. They are then dipped in a trough of water
having red, white, and green paint floating on the surface. A skilled
operator can stir the water in such a manner as to obtain various
patterns with the floating paint. When a slab of slate is brought into
contact with the surface the paint adheres and reproduces a pattern. It
is baked a second time, varnished, baked a third time, polished with
pumice, and finally baked a fourth time. This gives a "bloodstone"

SLATE 279

finish. If no green paint is used a " Venetian " finish results. Checker-
boards, flags, and various other designs also are made by this process.

"Struco" Slate. — A later development in surface decoration of slate,
to which the trade name ''Struco" has been applied, involves processes
that are quicker and less expensive then marbleizing. Color patterns are
applied as lacquers with a nitrocellulose base and a volatile hydrocarbon
as the vehicle or solvent. Unlike a paint, the drying and hardening are
brought about by evaporation rather than oxidation. A slate slab first is
polished with a belt sander or buffer. The lacquer is then applied to the
surface with a spray nozzle operated with compressed air. The highly
volatile solvent evaporates in 15 or 20 minutes, leaving a firm, hard
surface. A pattern is then applied over the base coat by a printing proc-
ess. A copper plate is engraved as a photographic reproduction of an
attractive veined marble. Lacquer is applied to the plate, and when a
soft-rubber roller is passed over it and then over the slate surface the
pattern is transferred in every detail. A transparent surface coat is then
applied; and, after hardening, it is carefully polished. Struco slate is
unaffected by sudden changes of temperature or by hot or cold water and
is highly resistant to chemicals. Moderately decorative surface finishes
are in demand for shower stalls and wainscoting, while the more orna-
mental types are used for table tops, radiator covers, lamp bases, smoking
sets, clocks, and various novelties. Struco products are not designed to
replace slate in its legitimate field but rather to find use in places where
colors other than the natural shades are desired.

SLATE FLOORS, WALKS, AND WALLS

Ornamental flagging is becoming increasingly important. Slate with
a honed finish and very close joints makes a beautiful floor. Material
from different regions permits floor designs in color patterns that vie in
beauty with the most ornate rugs and have the added value of indestructi-
bility by fire, water, or continuous wear. For paving yards, porches,
courts, roofs, or ornamental walkways, rough-textured, natural cleft
slates are employed. Two main styles are in general use. The "regular "
style consists of rectangular flags of various sizes and colors fitted together
with close joints; the "irregular" is made of random shapes and sizes that
are necessarily less closely fitted and require well-cemented joints.

Slates of various colors are being used as wall stone in such structures
as churches and college buildings, particularly in conjunction with other
kinds of stone, to produce variegated effects in color and texture.

CRUSHED AND PULVERIZED PRODUCTS

Slate crushed to sizes comparable with grains of fine gravel is known
commercially as "granules," the manufacture of which has developed
into an important industry. Granules range in size from 10- to 30-mesh

280

THE STONE INDUSTRIES

and are used to coat various forms of tar roofing. Although most granules
consist of slate, other materials, such as trap rock, shale, and serpentine,
are also used. The industry is, with few exceptions, distinct from the
manufacture of roofing slate; it is, in fact, a competitor, for large quanti-
ties of slate-surfaced roofing are now being sold for use not only on sheds,
garages, and other inexpensive structures but also on moderate-price

dwelling houses of a class
commonly roofed with slate.
Although slate quarry waste is
ground and pulverized to a limited
extent most plants making granules
and flour operate quarries exclu-
sively for these purposes, and in
nearly every instance the rock is
unsuitable for roofing or mill stock.
The types of crushing and grinding
equipment used vary widely.
Where a plant is erected primarily
for making granules, the purpose
is to crush with a minimum pro-
duction of fines, which are dis-
carded largely as waste, but where
there is a good market for pulver-
ized material a large proportion of
fines may not be regarded as a
disadvantage. Even where the
same type of product is desired
no two grinding plants are alike.
Variations are due to differences
in raw materials, amount of capital
available, and varying opinions
regarding efficiency of machines.
A flow sheet of a typical mill using
waste from a large Pennsylvania quarry which produces both roofing
and mill stock is shown in figure 57. The mill is electrically driven
with individual motors for each machine and produces both granules and
slate flour.

No. 5 GYRATORY CRUSHER

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BUCKET ELEVATOR

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ROTARY DRIER

I
BUCKET ELEVATOR

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BIN

BALL MILL
ELEVATOR

HUMMER SCREENS

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GRANULES 8-35 MESH

FINES

BIN

BLOWER
CAR

OVERSIZE

BIN

TUBE MILL

SCREW CONVEYOR

BATES BAGGER

BARRELING MACHINE

Fig. 57. — Flow sheet of a mill for manufactur-
ing slate granules and slate flour.

WASTE IN QUARRYING AND MANUFACTURING SLATE

An outstanding feature of the slate industry is the high proportion
of waste. It is reported that in one large quarry in Vermont about
15 tons of waste rock are removed for each ton of roofing slate recovered.
In most regions waste averages 70 to 90 per cent of gross production; in

SLATE 281

other places, particularly in underground mining, it may be as low as
50 or 60 per cent. In Wales 1 ton of slate is said to be produced for every
8 tons of waste rock quarried.

Waste is due to a variety of causes. Slate occurs in beds commonly
termed "veins" by quarrymen, though they are not veins in the sense in
which the term is used geologically. Beds of inferior rock alternate with
the good beds, and because of their intimate association the former must
often be removed to secure the latter. Furthermore, only part of the
good beds may be used, for much must be discarded because of such
imperfections as siliceous knots, ribbons, and cracks. A considerable
percentage also is lost in the process of removal ; blasting may shatter it,
or irregular fractures caused by wedging may result in loss. A further
heavy percentage of waste results from the manufacture of roofing
slates, and great quantities of refuse must be removed from beneath the
saws and planers of a structural slate mill.

Slate quarrymen have approached the problem of waste from two
angles. The first involves modifications in methods and machines
whereby a substantial reduction in the percentage of waste may be
attained ; the second concerns various ways in which waste slate may be
utilized.

Prevention of Waste. — Slate is subject to many natural imperfections
over which a quarryman has no control. If only 40 per cent of the mass
of rock blocked out in a quarry is usable, 60 per cent is the lowest mini-
mum to which waste may be reduced, even in theory. In actual practice
the proportion of waste must exceed 60 per cent by varying amounts
depending on the efficiency of quarrying and manufacture. If the final
product constitutes only 15 per cent of gross production and 85 per cent
is waste, obviously 25 of the 40 per cent, or five eighths of the good slate,
is wasted in quarrying and manufacture. A certain percentage of the
good rock must necessarily be lost in these processes, but whatever
share of this five eighths may be saved by improved processes or equip-
ment may be termed "preventable waste."

Much thought and experimenting have been devoted to ways of
reducing the proportion of waste. A first step is to plan development
systematically in conformity with rock structures. The imperfections
of slate and joints, ribbons, or other structural features can not be
changed, and the most orderly quarries are planned to minimize their
effects. A second step in conservation is care in the use of explosives.
Much waste results in some quarry regions from excessive blasting,
because the belief prevails that no other means can be used successfully
for separating primary rock masses. In other regions much more eco-
nomical methods have been worked out. Wire saws now widely used in
Pennsylvania have reduced waste in amounts ranging from 25 to 50 per
cent of the proportion under former processes. Channeling machines are

282 THE STONE INDUSTRIES

a great improvement over blasting methods, and wire saws represent
equal advancement over channeling.

Utilization of Waste. — Owing to imperfections of rock and the inevi-
table loss of material in quarrying and manufacture, a large percentage
of the gross production of slate quarries must be considered waste, even
under the most efficient quarrying and manufacturing methods. The
need for some useful outlet for waste slate has been felt for many years.
Various investigators have given attention to the problem, but results
have had little practical value. Slate consists of silicates that have few
uses compared with some other rocks. For example, limestone may be
used for lime and cement manufacture, agricultural purposes, and furnace
flux; while slate is unsuitable for these purposes. Its commercial
adaptability is, therefore, greatly restricted, and on this account all but
a very small fraction of the waste accumulation since slate was first
quarried is still lying in veritable mountains awaiting possible utilization.

Some years ago interest was centered in a Welsh enterprise for the
conversion of great quantities of waste slate into useful products.
Extravagant claims were made and the plant was operated for a short
time, but the enterprise failed; however, some progress is being made in
waste utilization in Great Britain.

Uses of Waste in Massive and Granular Form. — Waste slate from split-
ting shanties was at one time cut into 3- by 6-inch rectangles, set in
mastic on a backing of prepared roofing, and sold for use on flat roofs
under the name "inlaid slate." One plant operated from 1905 to 1917,
but there has been no production since. Waste slabs have been manu-
factured into perforated-slate lath and veneer. The latter product, which
was used for interior walls, consisted of a thin slab of slate attached to
gypsum board. These projects never advanced beyond the experimental
stage.

Manufacture of granules for slate-surfaced composition roofing has
developed into an important industry, but, as stated previously, only a
small fraction of the raw material is waste from slate quarries or mills.

Waste Slate as a Filler. — Waste rock from mills and quarries is used to
some extent pulverized. Many products, such as paper, rubber, road
asphalt, floor coverings, and paints require as one of their important
constituents a considerable percentage of finely pulverized inert mineral
matter to give "body." to obtain desired consistency, or to supply the
necessary wearing or other qualities demanded. Such materials are
known as "fillers." Slate dust is a satisfactory filler in many such
products.

To encourage wider use of waste slate the United States Bureau of
Mines in 1920 and 1921 cooperated in experiments with about 45 indus-
trial firms. The cooperating companies were manufacturers of rubber
products, linoleum and oilcloth, road asphalt, and plastic roofing.

SLATE 283

Plant and laboratory tests with samples of slate flour were conducted, and
results were submitted to the bureau for compilation. It was found that
finely pulverized slate is a satisfactory filler for mechanical rubber goods
but not for the higher grades of rubber, such as are used in automobile
tires. Slate flour gives good service as a filler in linoleum, oilcloth, and
window shades, except where white is desired. It is well-adapted for
filler in plastic roofing and flooring, and several hundred carloads are so
used every year.

Tests in laboratories of companies preparing road-asphalt mixtures
indicate that for resistance to impact slate flour about equals other
fillers in bonded briquets and is somewhat superior in sheet-surface
mixtures. In cementing value it was found to be superior to both lime-
stone and Portland cement in asphalt-bonded briquets and intermediate
between them in standard sheet surface mixtures. Elutriation tests
indicate that slate flour contains approximately 15 to 25 per cent more
fine dust that constitutes effective filler than limestone, trap rock, or
Portland cement. In low weight for a given volume — a desirable feature
of a filler, — slate is about equivalent to limestone and approximately
10 per cent superior to portland cement. Slate flour is therefore an
exceptionally good filler for road asphalt-surface mixtures.

Ground slate has been used in various ceramic products, but no
conclusive results have been obtained. On account of its low fusion
point it has some possibilities as a glazing material. Considerable
quantities of finely pulverized slate are consumed as paint filler. Pro-
ducers of slate flour in cooperation with consuming industries have
developed many uses in minor products.

It is evident, therefore, that slate flour may be employed in quite
a variety of ways, and some consuming industries are actual or potential
users of large quantities. However, slate flour, like granules, is produced
in very small amount from slate waste ; most of it is derived from quarries
worked exclusively for crushed and pulverized products.

TESTS AND SPECIFICATIONS

The grading of roofing slate varies in different localities. In the
Bangor district of Pennsylvania slates are graded as No. 1, clear; No. 2,
clear; No. 1, ribbon, where the ribbon is not exposed on the finished roof;
and No. 2, ribbon, where it is exposed. They are graded similarly at
Pen Argyl, Pa., with omission of No. 2 ribbon. At Slatington, Pa., and
in Vermont they are graded as No. 1, No. 2, and intermediate. Peach
Bottom slates are graded as No. 1 and No. 2. The Virginia product is
known in the trade as Buckingham slate and graded as No. 1 and No. 2.
Heavy, rough types are known as architectural grades.

To establish more uniform and definite grading the Federal Specifica-
tions Board has framed a specification for roofing slate to be used by

284 THE STONE INDUSTRIES

Government departments. Three grades, designated A, B, and C, are
based mainly on strength, absorption, and depth of softening when
immersed in an acid bath. The specification was pubhshed as of July 26,
1932.

Much valuable information on types of roofs, method of laying,
slope, gutters, flashings, snow guards, and other data a slate roofer
should know are given in an illustrated booklet, "Slate Roofs," issued
in 1926 by the National Slate Association.

Structural slate is graded as ribbon or clear in Pennsylvania and
according to color in Vermont. A series of pamphlets on data and
standards, issued by the Structural Service Bureau of Philadelphia, has
accomplished much in simplifying manufacture, in assisting architects
and builders to place orders for structural slate quickly and easily, and in
making it possible for manufacturers to fill orders promptly from standard
sizes kept in stock.

The requirements for electrical slate are more rigid than for structural
or roofing slate; in addition to easy workability it must have high dielec-
tric strength and must therefore be free of all ribbons or other conducting
materials. No definite specifications have been established, although
much progress has been made in perfecting testing methods.

Slate granules generally are limited in size between 10- and 30-mesh.
Equidimensional rather than flat grains are preferred. Fines are rigidly
excluded ; the percentage allowed usually is so low that granules in storage
ordinarily are air-cleaned while being loaded to remove the fines produced
in handling.

No generally used specifications have been adopted for slate flour as
it is used in many different products which have varied requirements.
Manufacturers of similar products differ widely among themselves in size
requirements for fillers. Producers of slate flour are obliged to modify
their milling equipment to satisfy the demands of individual customers.

MARKETING

Consideration of the uses of slate makes it evident that the chief
consuming industries are the building trades and manufacturers of elec-
trical equipment. As building construction is a nationwide industry, the
chief centers of consumption are fixed largely by freight rates, building
programs, and the activity of selling agents. Roofing slate is used
widely on buildings east of the Mississippi River, but because of former
high freight rates the demand west of the Mississippi was limited.
Recently rail-water rates have been reduced, and increasing quantities of
slate are reaching Pacific coast points by way of the Panama Canal.
Likewise, reduction of rates is opening up extensive markets south of the
Carolinas, where little slate has been used except in New Orleans. Here
the necessity for conserving the rain-water supply has encouraged the use

SLATE 285

of insoluble, sanitary slate roofs. Structural slate is less affected by-
freight and thus has a somewhat wider market than roofing slate.

The centers of electrical slate consumption are the large eastern and
middle western industrial cities, such as New York, Boston, Philadelphia,
Schenectady, Pittsburgh, Chicago, and St. Louis. The market for
blackboards is general throughout the United States and Canada.
Most school slates are exported. A marked growth in use of slate for
floors and walks has been evident since 1925 and is rapidly spreading
over the entire country, because the pieces are classed as "scrap" slate
and are carried at lowest freight rates. There is a scattered demand for
slate blackboards and for structural slate in the insular possessions of the
United States and in Cuba.

The chief marketing points for slate are Pen Argyl, Bangor, Slating-
ton, Easton, Bethlehem, Philadelphia, and Delta, Pa.; New York City;
Monson and Portland, Me.; Boston, Mass.; Granville, N. Y.; Poultney
and Fair Haven, Vt.; and Richmond and Norfolk, Va. There are
practically no seasonal fluctuations in the demand for electrical slate,
but owing to building inactivity the demand for structural, roofing, and
scrap slate is somewhat restricted in winter. Subnormal demand for
blackboards usually is in evidence during March, April, and May.

The slate industry has very difficult marketing problems. Lack of
more consistent growth in the industry is to be attributed chiefly to the
keen competition slate must meet in every line of consumption. Various
types of roofing are advertised much more widely, and many are syn-
thetic products that can be manufactured at low cost. Similarly, slate
meets much competition in structural and electrical applications.

Lack of efficient selling and advertising agencies also retards effective
marketing; those sections of the industry that are most inactive in this
respect are the least prosperous. There is, however, evidence of a move-
ment toward bettering this condition through establishment of joint
marketing agencies in some localities to bring about better contacts
between producers, distributors, and roofing and setting contractors, thus
promoting sales and insuring better service to ultimate consumers. The
outstanding problem in all slate regions is to find a large enough market to
absorb the normal output of the quarries. Marketing companies and
associations are exerting a growing influence, particularly in Pennsylvania
and Virginia. Sales organizations in Vermont and New York have been
effective only in marketing structural slate and that used for floors, walks,
and walls. Those who have the best interest of the industry at heart
contend that excellent service under the most exacting requirements will
enhance the salability of the products. Expansion of markets therefore
depends to quite a degree on proper classification of slate and on the
diversion of each type to the use for which it is best adapted. This
requires an exact and intimate knowledge of properties and qualities,

286 THE STONE INDUSTRIES

and to obtain the necessary fundamental data the National Slate Associa-
tion and Committee D-16 of the American Society for Testing Materials
are sponsoring studies of properties and methods of tests. The United
States Bureau of Standards and several college laboratories, notably those
of Lafayette College, Lehigh University, Pennsylvania State College,
Rensselaer Polytechnic Institute, and Massachusetts Institute of
Technology, are collaborating in these studies.

Persistent price-cutting, even at levels below the cost of production,
has characterized slate marketing. As this is due in a measure to an
insufficient knowledge of quarrying and milling costs an effort has been
made to establish better and more uniform cost keeping, and a cost-
accounting system for the industry has been published. ^^

Structural slate is sold to slate-setting contractors. Roofing slate is
sold to roofers and building-supply dealers through jobbers or brokers or
directly by quarry operators. To lessen breakage and prevent reducing
the requisite 3-inch head lap, nail holes for attachment of the slate
usually are punched before shipment.

Slate flour, granules, and scrap are sold by the ton, though scrap used
for floors and walks sometimes is figured in superficial feet. Granules
are sold in bulk in carload lots direct to manufacturers of composition
roofing. Slate flour is disposed of to paint manufacturers and marketed
in small amounts to miscellaneous users, such as manufacturers of roofing
mastic, rubber, and linoleum. It usually is sold in paper bags or wooden
barrels but may be marketed in bulk to large consumers. Roofing slate
sells by the square (enough to cover 100 square feet when placed on a
sloping roof with standard 3-inch head lap), mill stock and blackboards
by the square foot, baseboard by the running foot, and school slates by
the dozen.

IMPORTS AND EXPORTS

Slate imports range from $50,000 to $130,000 in annual value. There
are fluctuations from year to year, both in total and in relative amounts
from different countries. During recent years the chief sources of
foreign slates have been Italy, France, Portugal, Norway, and the
United Kingdom. About 15 per cent by value in 1929 was roofing slate.
The remainder was made up of blackboards and of slabs and other prod-
ucts not clearly specified.

From 1925 to 1929 annual exports of roofing slate ranged from 5,000
to 10,000 squares a year and had an average value of $9 to $12 a square.
Between 75 and 85 per cent were sold in Canada. Exports of other slate
products over a period of years are shown in the following table compiled
by the United States Bureau of Mines:

^* Bowles, Oliver, A System of Accounts for the Slate Industry. Rept. of Investi-
gations 2971, Bureau of Mines, 1929, 25 pp.

SLATE

287

Slate Other Than Roofing Exported from the United States, 1929-1930 and

1936-1937 BY Uses

Use

1929

1930

1936

1937

Quantity

Value

Quantity

Value

Quantity

Value

Quantity

Value

School slates, cases*

19,570

$108,135

16,280

$ 95,935

2,651

$ 20,204

4,434

$ 35,011

Electrical slate,

square feet

16,720

18,037

18,830

20,406

5,528

4,449

3,986

2,356

Blackboards,

square feet

188,720

74,610

177,760

59,810

53,486

15,502

26,033

6,853

Billiard tables,

square feet

20,150

34,455

15,760

9,802

26,729

10,601

30,443

16,580

Structural, square

feet

18,390

15,882

12,670

5,280

25,592

5,831

26,462

4,393

Slate granules and

"flour," short

14,250

84,185

27,540

162,000

9,412

67,012

11,184

77,576

$335 304

S353 , 233

$123,599

$142,769

* Cases weigh 130 to 165 pounds each; average is 135 pounds.

Practically all exports of roofing slate and granules, over 95 per cent of
the structural, and over 50 per cent of the electrical slate were shipped to
Canada in 1929. School slates also vi^ere shipped to Canada; but India,
Netherland East Indies, Australia, and New Zealand took the largest
quantities in 1929. South America, West Indies, and Asia furnished
markets for electrical slate; and Mexico, Central America, and the
Philippine Islands for billiard-table slate. The above data are typical
of the export trade in any year.

TARIFF

Before 1913 the duty on imported slates, chimney pieces, mantels,
slabs for tables, roofing slates, and all other manufactures of slate w^as
20 per cent ad valorem. The act of October 1913 reduced it to 10 per cent ;
that of September 1922 raised it to 15 per cent; and the act of 1930
raised it to 25 per cent ad valorem.

PRICES

Roofing-slate prices are quoted at times in trade magazines, though
many sales are made by individual bargaining at prices that may diverge
widely from those quoted in the market columns. The price per square
varies with the size, and the larger sizes command higher prices. The
average selling price of all kinds in 1929 was $10.65 a square. In 1932 it
was $7.43 a square.

Mill products are not quoted regularly, but list prices are supplied to
customers. The average selling price a square foot for the various

288 THE STONE INDUSTRIES

products in 1929 was as follows: Electrical, 80 cents; structural, 40 cents;
vaults, 26 cents; blackboards, 30 cents; billiard-table tops, 40 cents; and
flagging, 10 cents. Granules and slate flour sold at about $5.80 a ton.
The above figures are based on selling prices at the quarry or mill.
Prices were somewhat lower in 1930, 1931 and 1932.

Bibliography

AuBURY, Lewis E. The Structural and Industrial Materials of California. Cali-
fornia State Min. Bur. Bull. 38, 1906, pp. 149-154.

Behre, C. H., Jr. Observations on Structures in the Slates of Northampton County,
Pa. Jour. Geol., vol. 34, no. 6, pp. 481-506.

Mineral Industry 1927, 1928, 1929, 1930, and 1931 (chapters on slate).

McGraw-Hill Book Company, Inc., New York.

■ Geologic Factors in the Development of the Eastern Pennsylvania Slate

Belt. Am. Inst. Min. and Met. Eng. Tech. Paper 66, 1928, 18 pp.

Slate Deposits of Northampton County. Pennsylvania Topog. and Geol.

Survey Bull M 9, 1927, 312 pp.

- — Slate in Pennsylvania. Pennsylvania Topog. and Geol. Survey Bull. M 16,

1933, 400 pp.
Bowles, Oliver. The Characteristics of Slate. Proc. Am. Soc. Test. Mat., vol. 23,
pt. 2, 1923, pp. 524-534.

Fundamental Factors in the Testing of Mineral Products with Special

Reference to Slate and Related Materials. Proc. Am. Soc. Test. Mat., vol. 29, pt.
2, 1929, pp. 902-908.

The Technology of Slate. Bur. of Mines Bull. 218, 1922, 132 pp.

The Wire Saw in Slate Quarrying: Bur. of Mines Tech. Paper 469, 1930,

31 pp.

Consumption Trends in the Roofing Slate Industry. Bur. of Mines Rept.

of Investigations 3221, 1933, 3 pp. (mimeographed).

A System of Accounts for the Slate Industry. Bur. Mines Rept. of Investi-
gations 2971, 1929, 25 pp. (mimeographed).

The Marketing of Metals and Minerals (chapter on slate). McGraw-Hill

Book Company, Inc., New York, 1925, pp. 524-529.

Coons, A. T. Mineral Resources of the United States (chapters on slate). Pub-
lished annually by the U. S. Bur. of Mines (prior to 1924 by the U. S. Geol.
Survey, Minerals Yearbook since 1931.)

Dale, T. Nelson. The Slate Belt of Eastern New York and Western Vermont.
U. S. Geol. Survey, Nineteenth Ann. Rept., pt. 3, 1897-1898, 1898, pp. 153-307.

Dale, T. Nelson, and others. Slate in the United States. U. S. Geol. Survey Bull.
586, 1914, 220 pp.

Eckel, E. C. Building Stones and Clays. John Wiley & Sons, Inc., New York,
1912, pp. 95-126.

HiRSCHWALD, J. Handbuch der bautechnischen Gesteinspriifung. Verlag von
Gebriider Borntraeger, Berlin, 1912, 923 pp.

Kessler, D. W. and Sligh, W. H. Physical Properties and Weathering Char-
acteristics of Slate. U. S. Bur. of Standards Res. Paper 477, 1932, 35 pp.

Matthews, Edwar,d B. An Account of the Character and Distribution of Maryland
Building Stones (section on slate). Maryland Geol. Survey, vol. 2, 1898, pp.
214-232.

National Slate Association. Slate Roofs. Philadelphia, 1926, 84 pp.

North, F. J. The Slates of Wales. 2d ed., Univ. of Wales, Cardiff, 1927, 84 pp.

SLATE 289

Purdue, A. H. The Slates of Arkansas. Contributions to Economic Geologj^
1909, pt. 1 (f), U. S. Geol. Survey Bull. 430, 1910, pp. 317-334.

Richardson, C. H. Building Stones and Clays. Syracuse Univ. Book Store,
Syracuse, N. Y., 1917, pp. 267-302.

Shearer, H. K. The Slate Deposits of Georgia. Geol. Survev Georgia Bull. 34,
1918, 192 pp.

CHAPTER XI

SOAPSTONE

Production of soapstone is commonly considered part of the talc
industry, as talc is a constituent, but the uses of these commodities are
for the most part quite diverse, because at least 95 per cent of all talc
produced is sold pulverized while a large proportion of all soapstone
quarried is sold as blocks of various shapes and sizes. Soapstone is used
widely in construction and for building accessories, therefore it may
properly be called part of the dimension-stone industry.

COMPOSITION AND PROPERTIES

The term "soapstone" in its original sense apparently was synony-
mous with steatite or massive talc; however, it more properly includes all
dark gray to greenish talcose massive rocks which have a soapy feel and
which with few exceptions, are soft enough to be carved easily with a
knife. Nearly all soapstone produced for commerce is metamorphic rock
containing 10 to 80 per cent talc, a hydrous magnesium silicate of
composition expressed by the formula H2Mg3(Si03)4. The most char-
acteristic physical properties of talc are its softness (it may be scratched
easily with the finger nail) and its soapy feel. Although talc is the most
characteristic, and frequently the chief, constituent of soapstone other
minerals are present in varying amounts; chlorite, amphibole, pyroxene,
and mica are the more common constituents, with smaller amounts of
pyrite, quartz, calcite, and dolomite. Soapstone must therefore be
regarded as a rock rather than a mineral; and because of its variable
composition, its hardness and strength are also variable.

HISTORY

Soapstone was carved into ornaments by the ancient Egyptians and
Assyrians, and for many centuries the Chinese have used it for the same
purpose. It has long been used in limited quantities as a building mate-
rial. The cathedral of Trondhjem, Norway, is built of soapstone from
Gudbransdal.

Soapstone was first used in the United States by the American
Indians, who, recognizing its heat-retaining qualities, shaped it into
bowls, pots, cooking stones, and other objects now on display in many
museums. The term "potstone," which is still applied to soapstone in
some localities, originated from these early uses. Deposits in Albemarle

290

SOAPSTONE

291

County, Va., were opened on a semicommercial scale about 1880.
During later years the industry migrated into Nelson County, and recent
activity has been confined to the vicinity of Schuyler. A small produc-
tion has been noted at various times in Maryland, North Carolina, Rhode
Island, Vermont, and California, but Virginia has always dominated the
industry. A quarry near Marriottsville, Md., was reopened in 1933.

During recent years so much of the production has been in the hands
of a single company that figures can not be published without revealing
individual statistics. However, the following table, compiled from
United States Geological Survey publications, is presented as a record of
output for a number of years.

Domestic Soapstone Sold in the United States, 1916-1924

Year

Quantity,
short tons

Value

1916

19,127

S 489,606

1917

19,885

402,506

1918

12,330

501,059

1919

16,504

530,163

1920

19,707

709,400

1921

17,423*

627,826*

1922

22,700

712,144

1923

22,857

932,098

1924

25,630

1,288,885

* Sawed and manufactured talc included under soapstone.

USES

The uses of soapstone are related intimately to its physical properties.
Its easy workability, light color, and resistance to weathering or water
action fit it admirably for many structural purposes; laundry tubs, sinks,
aquariums, wainscoting, mantels, baseboards, stair treads, tiles, and
spandrels are made of soapstone. Floor tile and steps sometimes are
calcined to make them harder than rock in its natural state. Because
of its resistance to chemical action and low absorptive properties soap-
stone is adaptable for laboratory table tops and sinks, hoods, ovens, acid
tanks, vats, trays, development tanks for photographs and blue prints,
drains, and furnace blocks for lining retorts in paper mills. Some
soapstones have high dielectric strength, which, combined with easy
workability, makes them desirable for electrical insulation units, such as
switchboards, panels, barriers, fuse guards, bases, circuit-breaker com-
partments, insulating floor slabs, battery-room flooring or shelving, and
similar products. Because of its ability to resist and to retain heat,
soapstone is employed for griddles, foot warmers, fireless cooker stones,

292 THE STONE INDUSTRIES

fireplaces, hearths, and furnace linings; some of these uses, however, are
declining.

Soapstone is divided into three grades — soft, regular, and hard.
The high heat resistance of the soft grade makes it especially desirable for
furnace linings and other uses where high temperatures prevail. The
hard grade, containing a large proportion of the harder siliceous minerals,
such as hornblende and actinolite, is best suited for stair treads, floor tile,
and other products subject to wear. The regular grade, midway in
properties between the hard and soft, is by far the most abundant.
Virtually all fabricated equipment having interlocking joints, such as
laundry tubs, sinks, and sanitary partitions, is made of soapstone of this
quality.

Granular soapstone, hardened by heat treatment, is used for surfacing
prepared roofing. Pulverized waste material is employed as an admix-
ture in concrete and as a filler and sold to some extent for dusting coal
mines.

ORIGIN AND OCCURRENCE

Most soapstone is regarded as an alteration product of basic igneous
rocks rich in magnesium. The extensive deposits near Schuyler, Va.,
consist of irregular or lenslike dikes bordered with mica schist and
peridotite. These deposits have been studied and described in some
detail, but very little is known of the occurrences in other States. The
important deposits in Virginia form a belt which extends through Nelson,
Albemarle, and Orange Counties and for many years have constituted
the chief source of supply. Small deposits have been noted in Fairfax,
Franklin, Amelia, and Henry Counties. Soapstone is quarried near
Thetford Mines, Quebec, Canada, for production of furnace blocks and
pulverized products.

QUARRY METHODS

The normal size of quarries at Schuyler, Va., is 100 feet long by 100 to
120 feet wide, the width being governed by the size of the dike. Enough
soapstone to provide a good face is left in place along the hanging wall.
If several quarries are opened on one dike, walls 22 feet wide are left
standing between operations. The depth to which a quarry may be
worked depends on safety of the walls; the average depth is nearly
200 feet.

Overburden is removed chiefly by steam shovels and drag scrapers,
though hydraulic methods have been used. Occasionally good stone is
found near the surface, but usually the upper floors are removed as waste.
No explosives are used in either waste or good rock. Overburden and
waste usually are dumped into pits that have been worked out and
abandoned.

SOAPSTONE

293

A stripped quarry floor is channeled across the strike with steam
or electric-air machines. The distance between channel cuts is 4 to
6 feet, and the average depth 6>^ feet. After a center row of key blocks
is removed all other channeled masses are undercut to their full depth.
An undercutter is a reciprocating machine that works like a channeler.
In soft rock a Jeffrey longwall undercutter with stellite teeth is used
satisfactorily. One end of the undercut mass is channeled across and
the end block broken out. The mass is then subdivided by drilling holes
parallel to the natural parting planes of the rock, and by splitting with
wedges. As the natural grain dips at angles of 30 to 60° blocks
are roughly diamond-shaped. An average block is 4 by 4 by 6 feet.
Each is graded according to hardness, color, and soundness. Swinging-
boom derricks lift them from the quarry floor and place them on cars or
stock piles, depending upon current mill requirements.

MILLING PROCESSES

As with other types of dimension stone, sawing is the first step in
manufacturing soapstone products. Gang saws, like those used for

Fig. 58.

-Two soapstone saw mills with overhead traveling crane between them, Schuyler,
Va. (Photo by H. Herbert Hughes.)

marble and limestone, are employed, and 30- to 46-mesh sea sand is
used as abrasive. Saws travel back and forth at about 84 complete
strokes a minute in the day time, while at night when other machinery is
shut down the speed is increased to about 100 strokes a minute. Gangs
cut through the stone at about 4 inches an hour. Most of the stock is cut
into thin slabs, which results in less waste from oblique-angled blocks
than if cubic stock were manufactured. For most uses saw cuts are made

294 THE STONE INDUSTRIES

to parallel the grain. Sawed slabs are transferred to either a stock mill
or a custom mill. Figure 58 illustrates two soapstone saw mills with an
overhead traveling crane between.

A stock mill produces standard products, such as laundry tubs, sinks,
and furnace blocks. Trimming is done with a steel-toothed hand saw
similar to that used in wood working. The slab surfaces are finished
on rubbing beds and tongued and grooved with Carborundum wheels.
In assembling tubs one small bolt secures each corner but is not exposed
in the interior. All joints are set in cement, consisting of linseed oil,
litharge, and whiting, which expands as it seasons, insuring watertight
joints. An important function of a stock mill is the manufacture of
furnace blocks. These are made in numerous sizes and shapes 3 inches
to 3 feet long. Blocks are cut with circular diamond saws, and care is
taken that the direction of grain is always at right angles to the exposed
surface when a block is set in place; otherwise, it is liable to spall.

All other soapstone, consisting chiefly of structural material, is
fabricated in the custom mill according to specifications. The general
procedure is similar to that in a stock mill, except that blue prints are
followed on all jobs. Furthermore, much stone used in the custom mill
is harder than that employed for laundry tubs or furnace blocks. There-
fore, circular silicon carbide saws are used instead of hand saws for
trimming, and Carborundum grinders supplement rubbing beds. Rub-
bed slabs pass to a checker, who designates from blue prints the additional
fabricating to be done. Completed slabs are assembled in the mill or
on the job, depending on the nature of the order.

Some higher-grade waste soapstone is pulverized as filler, chiefly for
use in the rubber industry. For this purpose crushers, hammer mills,
tube mills, screens, and air classifiers are the chief types of equipment
used.

MARKETING

Markets for soapstone are world-wide, but only a small proportion
of the production is exported. The largest consumption is east of the
Mississippi River, particularly in the Atlantic Seaboard States. The
increasing use of soapstone for architectural purposes during recent years
has resulted in fluctuations in demand that parallel the seasonal activity
of building. Shipments are now made almost entirely by rail and
wherever practical in carload lots. Most soapstone products, except
furnace blocks, are crated.

There is at present practically no competition within the industry in
marketing soapstone. However, it meets with very keen competition
from other materials, including marble, slate, sandstone, limestone, and
certain synthetic products, in virtually every market except for furnace
blocks.

SOAPSTONE 295

The unit of measurement for manufactured soapstone is a square foot
13^^ inches thick. All products, regardless of size, shape, or use, are
reduced to this unit. Furnace blocks comprise the largest low-priced
output, while complicated development tanks and similar equipment
requiring much skilled labor bring the highest prices. Nearly all sales
are made direct to builders and contractors; there are no brokers or
middlemen.

ROCKS RELATED TO SOAPSTONE

A metamorphic rock known as "greenstone," consisting essentially of
actinolite and chlorite, outcrops prominently at Lynchburg, Va. It has
an attractive unfading green color that renders it suitable for structural
and ornamental building. Many years ago it was used as a local build-
ing stone. Basements, chimneys, and entire houses made of it show no
evidence of change or deterioration. During recent years the quarries
have been reopened, and a mill has been constructed for the manu-
facture of structural and decorative slabs and other products.

Bibliography

Bowles, Oliver. Chapters on Talc and Soapstone. Mineral Industry, 1930 and

1931, McGraw-Hill Book Company, Inc., New York.
Bowles, Oliver, and Stoddard, B. H. Chapters on Talc and Soapstone. Bur.

of Mines Mineral Resources of the United States, for 1928, 1929, 1930, and 1931.

(Included in chapter on dimension stone in Minerals Yearbook after 1931.)
BuRFOOT, J. D. The Origin of the Talc and Soapstone Deposits of Virginia. Jour.

Econ. GeoL, vol. 25, 1930, pp. 806-826.
Hughes, H. Herbert. Soapstone. Bur. of Mines Inf. Circ. 6563, 1931, 18 pp.
Ryan, C. W. Soapstone Mining in Virginia. Am. Inst. Min. and Met. Eng. Tech.

Pub. 160, 1929, 31 pp.

CHAPTER XII

BOULDERS AS BUILDING MATERIALS
ORIGIN AND NATURE OF BOULDERS

The term "boulders" is applied to loose fragments of rock as con-
trasted with solid beds or masses, which are designated "rock in place,"
and is restricted to masses that have become loosened from the parent
ledge by natural processes, such as by water, frost action, or glaciation.
Boulders usually are plentiful in rugged regions where bedrock is close
to the surface and along old shore lines and river beds. They are rare or
absent in ancient lake beds that are now land areas or in deltas or out-
wash plains of rivers, for only the finer, lighter products of rock disintegra-
tion are disposed in such places.

A great difference is to be observed between boulders in northern
states compared with those in the south. In its southward movement
the great ice sheet of the glacial age reached northern New Jersey, central
Pennsylvania, and, roughly, a line that followed the Ohio and Missouri
Rivers. North of this line most of the surface soil is glacial till, and much
of it remains in the condition in which it was left by the ice, though large
areas have been re worked and assorted by water action. Materials
carried by the ice may have been picked up at widely separated points and
carried long distances. Boulders in glacial regions may therefore consist
of a great variety of rocks; granites, gneisses, syenites, limestones, sand-
stones, and conglomerates may all be found within a restricted area.
Usually they are rounded and show other evidences of excessive
wear.

In the area south of the southern limit of glaciation some boulders
may have been transported limited distances by rivers or other agencies,
but for the most part they are of local origin. In limestone regions
boulders consist of fragments of underlying limestone; likewise, in granite
regions, few, if any, are to be found that are not related directly to
outcrops in the immediate neighborhood. Ordinarily they are more
angular than those of glaciated regions.

As nature had thus fashioned building blocks and left them conven-
iently placed on the surface of the ground they probably constituted
materials for the most primitive habitations built by ancient races.
Their ready availability led to early use by pioneers, and they are still
important construction materials.

296

BOULDERS AS BUILDING MATERIALS 297

STONE FENCES

A use of stone of which Httle mention has been made is as fencing.
The subject has been neglected because it falls midway between two great
jBelds of activity — mining and agriculture. A very small part of such
stone is quarried rock; nearly all of it consists of boulders picked up by
farmers while working in their fields. Employment of stone in this way
serves a twofold purpose — clearing land of annoying obstructions and
fencing it. Such work must be classed as farm labor; it is not properly
part of the mining industry. Compilers of agricultural statistics are
interested in the size of fields and mileage of fences but have subdivided
fences by kinds to a very limited extent. Hence, for quite logical reasons,
no record has been kept of the mileage of stone fences or the amount of
material used in their construction.

Most stone fences now in existence were built many years ago. It
was necessary for pioneer farmers to clear the land, and labor being
cheap, the cost of building stone walls along the borders of fields was not
excessive.

Stone has long been a choice material for ornamental walls and fences
in town and suburban estates. Since such walls are erected for archi-
tectural effect rather than practical value waste rock is used little, but a
surprisingly large amount of quarried rock cut into regular dimensions
and having a rather high marketable value is so consumed. Walls and
fences of this material look so solid and rugged that they are invaluable
artistic additions to any home.

Certain objections have been raised to stone fences. Unless well-
built, sheep can scale them; they harbor weeds, brush, insects, and
burrowing animals; and their removal for the enlargement of fields is
expensive. On the other hand, such fences, properly built with foun-
dations that will not heave with frost action, are the most enduring of
all types ; moreover, they are attractive and are fireproof, often preventing
a blaze spreading from field to field.

The extent to which stone is used for fencing is quite variable in
different parts of the country. Throughout the Great Plains region of
the Middle West very little stone occurs, and the Rocky Mountain and
Far West States have few stone fences. In the New England and other
Eastern States, however, granite and limestone boulders abound and
have been widely used for this purpose. Throughout Connecticut,
Rhode Island, and other Northeastern States there are miles and miles
of fences made of the abundant granites and other igneous rocks. In
northern Virginia many roads and fields are neatly fenced for long
stretches with limestone boulders.

Data for determining the mileage of stone fences in the United States
are meager. In so far as the writer has ascertained statistics cover only

298 THE STONE INDUSTRIES

the North Central States and certain selected parts of New York. The
first of these areas comprises States where very little stone is found on
farms, and consequently few such fences are built. According to a
report^^ of the United States Department of Agriculture only about
0.17 per cent of the fences were of stone in the following 11 States: South
Dakota, Nebraska, Kansas, Minnesota, Iowa, Missouri, Wisconsin,
Illinois, Michigan, Indiana, and Ohio. In this group Wisconsin stands
highest, with 0.8 per cent. A second recorded study by Myers^" covered
53 farms in New York averaging 173.4 acres each. The average length
of stone fence per farm was 122.5 rods, or 8.1 per cent of the total fencing.
In certain sections the percentage ran as high as 36.

If it is assumed that the figure 8.1 per cent, obtained by Cornell
University for parts of New York, typifies the more rugged and older
settled parts of the East, which occupy about one sixth of the area of
the United States, and that the figure, 0.17 per cent, obtained by the
United States Department of Agriculture for the North Central States,
is a fair average for the rest of the country, a basis has been established
for estimating the total extent of stone fences. Figures thus obtained
may be far from correct, but they at least supply an estimate on which to
hinge comments until better figures are obtainable.

According to census figures, some years ago there were 5,371,000,000
rods of fence in the United States. On the basis given above the approxi-
mate length of stone fences would be 78,620,000 rods or about 246,000
miles.

To determine the cubic contents of this volume of fencing a certain
amount of guesswork again is required, for fences are not of uniform
size; some built long ago are massive, while others, especially those built
more recently are of much smaller proportions. Many limestone fences
in Virginia are about 2 feet wide at the bottom, 1 foot wide at the top,
and 43^^ to 5 feet high. If average dimensions are assumed to be 2}'^
feet wide at the bottom, 13-^ feet at top, and 5 feet high, the total volume
would reach the staggering figure of nearly 13,000,000,000 cubic feet.
Practically all the fences are dry walls built without mortar. The stones
are laid carefully and packed so closely that the air spaces between them
probably do not occupy more than one fourth of the entire volume.
Assuming that three fourths of the volume is solid stone weighing about
160 pounds to the cubic foot the weight of stone used in fences approaches
780,000,000 tons, which is equivalent to about 280 times the pro-
duction of dimension stone in the United States in 1931. The figures

33 Humphrey, H. N., Cost of Fencing Farms in the North Central States. U. S.
Dept. of Agriculture Bull. 321, 1909.

'"' Myers, W. I., An Economic Study of Farm Layout. Cornell Univ. Agric. Exp.
Sta. Memoir 34, 1920.

BOULDERS AS BUILDING MATERIALS 299

given above may, of course, be very much in error, but at least they show
a use of stone of very great magnitude.

This lowly application that finds no place in statistics and little
mention in song or story fills in toto an important place in rural life.
But what of the future? As stone fences gradually deteriorate through
action of the elements, the high cost of labor for repairs or rebuilding
leads to replacement of many of them with wire fences. The widening of
highways and enlargement of fields may also demand their removal. The

!• iG. 59. — Graceful limestone fences in Virginia. (Photo by the author.)

material from some of them has been used for building purposes, or
crushed for hard-road construction. Diminishing use is in prospect,
but any movement toward wholesale destruction is to be regretted, for
nothing is more enduring than the rocks from which this old world is
made. Not only are stone fences substantial and long lived, but they are
picturesque and lend an attractiveness to rural landscapes that would be
sadly missed.

It is evident that the dignity, stability, and ruggedness of stone
fences are fully appreciated in some localities. During active repaving
and road widening in northern Virginia in 1930 and 1931, numerous
stone fences were moved back and rebuilt in attractive forms that
enhance the beauty of an already charming landscape. Pillored gate-
ways and graceful curves, as illustrated in figure 59, feature both new
and old fences. Such structures add the charm of artistry to the utility
of substantial and enduring stone.

USE OF BOULDERS IN BUILDINGS

As stated previously, boulders were used by the early settlers long
before the days of quarrying. Although modern methods have made it

300

THE STONE INDUSTRIES

possible to shape bed rock into building units quickly and at moderate
cost, the use of boulders has by no means been abandoned; they are still
popular and are widely used. Perhaps their most prominent use is in
rustic fireplaces and exterior chimneys, the latter constituting prominent
features of many beautifully designed residences. They are also used
extensively for basements, lower courses, and porch walls. Entire
exterior house walls of boulders are by no means uncommon; in fact, the
present demand for ruggedness and variety in architecture has led to
increasing use. An unusual use is shown in figure 60.

Fig. 60. — A unique type of boulder construction combining chimney with stairway.

hy H. Herbert Hughes.)

{Photo

As mentioned heretofore, the greatest variation in materials is in
glaciated country. In such regions boulder houses may have in the same
wall granites, gneisses, syenites, trap rocks, limestones, sandstones, and
mica schists interspersed occasionally with beautiful red jasper
conglomerates.

The use of boulders is not confined to modest dwelling houses.
Many mansions costing thousands of dollars, mountain resorts, hotels,
and public buildings are built largely of them. Farmers may be paid
by the wagon load for hauling rocks from their farms to build such
structures. Although the work of construction is slow and expensive
many buildings of this type are of beautiful rustic design; they will
endure for many years, and their maintenance cost is low.

CHAPTER XIII

FOREIGN BUILDING AND ORNAMENTAL STONES^i
SCOPE OF DISCUSSION

Many foreign countries are rich in structural and ornamental materials
of mineral origin. In the Old World structural stones were used far
back in prehistoric ages, and the acid test of time has proved that many-
are remarkably enduring. Multitudes of beautiful, serviceable American
stones are no doubt just as capable of resisting the storms of centuries,
but our New World civilization is as yet far too young to prove their
qualities. In European countries magnificent cathedrals and other
public buildings erected centuries ago are centers of interest for travelers
from all nations. It is fitting, therefore, that some attention be given
to the sources of supply of materials which people of foreign lands have
found to be essential for the noblest and most substantial types of
architecture.

The primary purpose of this book is to cover adequately the stone
industries of the United States, for space would not permit a treatise
covering in detail these industries throughout the world. Nevertheless,
many foreign stones are now, or have been, used extensively in America,
and it is therefore desirable to give some attention to those that are
used in conjunction with, or as substitutes for, stone of domestic origin.
As brevity is necessary, attention will be given chiefly to stones from other
lands that find prominent use in the United States.

IMPORTS OF STONE

To indicate the extent to which foreign stones are used in this country,
a table of imports compiled by the United States Bureau of Mines is
shown on page 302. It comprises a table covering stone, to which has
been added the value of imported slate.

The future consumption of foreign stone in America is hard to predict.
Demands during the depression years were subnormal and, coupled with
depressed markets, imports have been and will continue to be influ-
enced by the tariff revision of 1930 and subsequent revisions.

*i Acknowledgment is hereby made of helpful information obtained from certain
unpublished manuscripts on foreign building stones compiled some years ago by
T. C. Hopkins for the U. S. Geol. Survey.

301

302

THE STONE INDUSTRIES

Stone Imported for Consumption in the United States, 1929-1930
AND 1936-1937, BY Kinds

1929

1930

1936

1937

Kind

Quan-
tity

Value

Quan-
tity

Value

Quan-
tity

Value

Quan-
tity

Value

Marble, breccia,

and onyx:
In blocks, rough,

etc., cubic feet
Sawed, cubic feet
Slabs or paving

tiles, superficial

feet

667,900
10,859

649 , 899

$1,591,070
24,799

253 , 267
566,010

1,908

717,436
797

591,616

$1,578,856
2,983

254 , 179
329 , 279

12,157

60,784
172

150,364
5,609

$256,922
712

58,979
43,879

140

75,302
165

214,588
9,362

$297 , 501
488

67 , 789

All other manu-

69 , 403

Mosaic cubes of
marble or onyx.

180

Total

$2,437,054

$2,177,454

$360,632

$435,361

Granite:

Dressed, cubic
feet

$ 292,644
378,943

138,831

$ 266,318
202,037

16,233
43 , 089

$ 67,293
63 , 627

36,853
43,871

$178,607

Rough, cubic feet

216,022

67,212

Total

$ 671,587

$ 428,355

59,322

$130,920

80,724

$245 819

Quartzite, short

*
*

102,032t
74,163t

$ 174,334t
64, 997 t

50,704
48,917

$ 91,120
67,185

139,533
13,404

$249 003

Travertine, cubic
feet

18 677

Stone (other) :

$ 62,674

184,620
233,324

214,424

$ 23,396

203,417
73,908

2,229
3,939

$ 5,471

3,688
7,050

2,647
6,287

$ 6,310

Rough (monu-
mental or
building), cubic
feet

240,399

6 617

Rough (other).

19 639

Total

$ 480,618

$ 300,721

$ 16,209

$ 32 566

Slate

$ 95,073

$ 48,065

$ 4,851

$ 4 824

Grand total

$3,684,332

$3,193,926

$670,917

$986 250

* Not separately classified.

t Figures cover June 18 to December 31: not separately classified prior to change in tariff.

FOREIGN LIMESTONES

Canada. — The Tyndall limestone of Ordovician age, occurring about
30 miles northwest of Winnipeg, Manitoba, generally is regarded as the
best building limestone in western Canada. The main productive ridge
is about }4 mile wide and 1 mile long, although less easily available rock
occurs over a much wider area. Two main types of stone are obtained —

FOREIGN BUILDING AND ORNAMENTAL STONES 303

an upper buff-mottled stone in beds 12 to 13 feet thick in all, and a lower
blue-mottled stone 5 to 6 feet thick. Both kinds extended below the
floor of the quarry at the stage of progress covered by Park's original
description (see bibliography), and the total thickness of the formation
was about 130 feet. The rock has a characteristic mottled appearance
due to evenly distributed dark patches. Blocks are sawed, cut, and
carved in large, well-equipped finishing mills, either at the quarries or in
Winnipeg. Some waste material is burned into lime. The product is
used widely for public buildings in Winnipeg and other midwestern cities.

Limestones are plentiful in Ontario, and numerous quarries have
been opened in many localities. Most of them, however, are small and
supply stone only for local use. Dark, heavily bedded limestones of the
Black River formation have been used so widely in Kingston that it has
been called the Limestone City. Other noteworthy occurrences are the
Trenton, which is used to some extent in Ottawa; the Niagara limestone
at Hamilton; and the Onondaga near St. Marys. The largest building
limestone quarry in Ontario is at Queenston near Niagara Falls. While
it has been worked for many years, activities have been enlarged greatly
under new ownership since 1925. Rock of high quality occurs in iflat-
lying beds about 15 feet thick all told, with a moderate overburden.
The stone is a pleasing silver gray that mellows with time. It has low
absorptive properties and is highly resistant to weathering. The quarry
product is sold as rough blocks or slabs for fabrication in independent
mills. It is used in constructing many large buildings in Hamilton,
Toronto, and other Canadian cities.

Numerous buildings in Montreal are made of limestone quarried in or
near the city. The stone belongs to the Chazy and Trenton formations
and is of three main types. The first, a grayish, medium-grained, semi-
crystalline limestone is of the highest grade and is suitable for cut stone.
The second, a hard, dark, fine-grained variety, and the third, an inter-
banding of the first and second, are used mainly for rock-faced work.
Trenton limestones have been quarried extensively in Portneuf County,
Quebec, and used for building purposes in Quebec city and in Montreal.

Cuba. — Buff and blue oolitic limestone is quarried in the suburbs of
Havana. It is somewhat like Indiana limestone but is finer-grained and
softer. It may be cut readily with an ax or hand saw but hardens upon
exposure. As the deposit is conveniently situated and easily worked the
stone is used quite extensively for building houses in Havana.

Bermuda. — Bermuda limestone is a porous aggregation of shell and
coral fragments, ranging from a chalky, white, fine-grained, soft type to a
darker, coarser, and harder form. It is worked so easily that blocks are
cut out with long-handled chisels and subdivided to desired sizes and
shapes with hand saws. Many houses are built of the softer types; even
the roofs consist of thin slabs. When whitewashed this variety is

304

THE STONE INDUSTRIES

durable enough for a mild, moderate climate like that of Bermuda. The
harder rock has been used for fortifications and other Government works
on the islands.

France. — The Caen stone, a Jurassic oolitic variety quarried near
Caen, Falaise, and Bayeux in Normandy, is one of the best known lime-
stones of France. It is a soft, fine-grained, light-colored rock admirably
adapted for carved work. While not suitable for outdoor use in a climate
like that of the United States it has been popular for many centuries as
an interior decorative stone, particularly in Gothic architecture. It was

Fig. 61. — Underground limestone mines, Commercy, France. (Courtesy of J. B. Newsom.)

shipped to England in large quantities shortly after the Norman con-
quest and employed in such notable structures as the Cathedral of
Canterbury and Westminster Abbey. The workable beds have a
maximum thickness of 20 to 25 feet and cover a wide area. Most of the
workings are underground, though some stone is taken from open
quarries. It is shipped by water to various European ports and to
America.

Jurassic oolitic limestones are quarried also in the Department of
Meuse on the east side of the Paris Basin. Highly fossiliferous stone,
consisting chiefly of crinoid fragments, is obtained from open-pit quarries
at Euville and Lerouville and from underground workings at Commercy.
The latter are shown in figure 61. This has been used for fortifications,
canals, and many notable buildings in Paris. "Comblanchien" is a well-
known Jurassic type. As shown in figure 62, canals are of great assist-
ance in transportation.

Large quarries of similar stone have long been worked near Auxerre
in the Department of Yonne southeast of Paris. It is reported that 43

FOREIGN BUILDING AND ORNAMENTAL STONES 305

quarries were operated in 1889. Large sawmills were employed to shape
blocks for the construction of canals and as building stone used in France,
England, Belgium, and the United States.

Jurassic oolites and Lower Cretaceous limestones are quarried exten-
sively near Grenoble in Isere. ''Eschaillon White," "Eschaillon Rose,"
and "Eschaillon Yellow," some varieties of which are classed as marbles,
have been used for architectural purposes in various French cities. The
rose variety occurs in a bed 4.5 meters thick, while the white is 16.5
meters thick.

Fig. 62. — .\ canal in France used for transporting stone. (Courtesy of J. B. Newsom.)

Tertiary limestones of the Paris Basin have been worked in extensive
underground galleries since the early Christian era. The most important
building-stone stratum, known as the calcaire grassier, or big limestone
bed, is a fossiliferous yellowish to grayish white stone coarse to fine in
texture. In mining the high-grade rock in beds only 16 to 20 inches
thick several feet of waste rock are removed to obtain working space in
the galleries. The architectural beauty of Paris is due in no small part
to the patience and industry of miners who drove tunnels many miles
beneath parts of the city to obtain a building material of such superior
quality and attractiveness that it has been preferred to most other
structural products.

The Tertiary limestones of southern France have been used widely
for building. This great belt extends eastward from the Pyrenees
through the Alps and Apennines into Greece and through the Carpathians
and Balkans into Asia Minor, and continues through central Asia to
China and Japan. It occurs south of the Mediterranean Sea in Egypt
and in the Barbary States. An important bed, known as the Num-

306 THE STONE INDUSTRIES

mulitic limestone, has been quarried in most of the countries through
which it passes and provided stone for such famous structures as the
Great Pyramid of Cheops and many buildings in the Holy Land.

Belgium. — One of the best building limestones of Belgium is a
bluish gray to black fossiliferous rock of Devonian age. Some of it is
composed almost entirely of crinoid fragments, assembled in such a way
as to present a granitic texture, on which account it is called petit granit.
It works easily, has high crushing strength, and resists weathering remark-
ably well. Large quarries are worked at Ecaussinnes, Soignies, Arquen-
nes, and Feluy in Hainaut, at Spontin in Namur, and Sprimont in
Liege. Other quarry centers are Maffl.es, Anthisnes, Comblain au Pont,
Denee and Les Awins. High quality stone has been quarried at Soignies
since 1740 and used extensively along the canals of Holland. It is also
exported to Germany, France, England, and the United States. Some is
designated commercially as marble. The lower beds are quarried with
wire saws; the standards are set in core-drill holes 3 feet in diameter and
about 13 feet deep.

Italy. — Travertine is usually classed as limestone. The most famous
deposits in the world occur near Tivoli about 16 miles east of Rome.
Del Barco near the famous baths of Acque Albule at Bagni, a railway
station between Rome and Tivoli, is one of the oldest quarries. It
furnished stone during the days of the Roman Empire. According to
information obtained from Frank L. Hess of the United States Bureau of
Mines, who visited the district in 1929, the quarry was about 1,000 feet
long and 22 feet deep. The overburden is unconsolidated material
10 to 15 feet thick, much of which consists of artificial accumulations.
Rock at the western end of the quarry is variegated gray and white,
stained with iron oxide in places. In recent years this type has become
more popular, whereas formerly the only kind used was the more regularly
colored rock at the eastern end of the quarry.

For several centuries blocks were separated by a slow process of
cutting hand-picked channels on four sides and then wedging up at the
floor. The stone is now cut with wire saws into blocks about 10 meters
long, 1 meter thick, and 2 to 3 meters high. The length is governed by
the spacing of major joints, some of which have been widened enough by
solution to afford room for setting up standards for the guide wheels.
The rate of sawing is about 4.5 square feet an hour. When long masses
are cut to the bottom they are wedged free at the floor, and broken across
in several places. Each block is turned down by fastening a wire cable to
it and pulling it over by means of a capstan turned with oxen. Irregular
blocks are trimmed to shape with wire saws. Large rectangular masses
are cut into thin slabs with gang saws using sand as abrasive. It was
reported that blocks could be put on cars at Bagni for about 350 lire a
cubic meter and on board trans-Atlantic ships for about 400 lire. In

FOREIGN BUILDING AND ORNAMENTAL STONES 307

1929, the time of this estimate, 19 Ure were equivalent to about one dollar.
The above costs, therefore, were respectively about 56 and 71 cents a
cubic foot.

The travertine area is extensive, and several quarries other than
that described are worked. St. Peter's, one of the greatest churches in
the world, and the famous Colosseum, the largest theater, begun by-
Vespasian in A.D. 75 and dedicated by Titus in A.D. 80, were built
chiefly of travertine from the Tivoli quarries. During the fifteenth and
sixteenth centuries the Colosseum was used as a quarry where stone was
procured for many churches and palaces in Italy, notably the Piazza
di San Marco in Venice and the historic Palazzo Farnese in Rome.
Demolition was finally stopped, and the structure was partly restored.
During recent years large quantities of Italian travertine have been
imported for interior decorative and structural uses in America. The
Pisani quarry, not far from the Del Barco, supplied travertine for the
Pennsylvania Railway Station in New York, which attracted much
attention and popularized the use of Italian travertine in America.
As shown in the the table of stone imports on page 302, travertine was not
separated from other stone imports before 1930. It has been stated in
hearings before the United States Tariff Commission that imports for
some years amounted annually to about 100,000 cubic feet, and that the
selling price in New York was about $2.25 a cubic foot.

A closely related calcareous tufa is obtained near Naples. Blocks
are quarried and prepared for market entirely by hand methods.

England. — The most notable building limestone of England is a
Jurassic oolite occupying the same prominent position in the building
trade of that country that the Caen stone holds in France and Indiana
limestone in the United States. The formation is divided into four
bands: (1) The upper (Portland), (2) the middle (Oxford), (3) the lower
(Bath), and (4) the Inferior Oolite. The first and third are most import-
ant, although the fourth has supplied much good building stone.

The Bath stone of the lower beds quarried in Wiltshire is the most
famous and most widely used. About 2,000,000 cubic feet are quarried
annually for domestic use and export. The rock is softer, finer-grained,
and more uniform than the Portland stone described later and is admir-
ably suited for the delicate carvings of Gothic architecture. It is a pure
limestone containing more than 97 per cent calcium carbonate. The
most important workings are in the Somerset Hills near Bath, where
beds are 12 to 25 feet thick and very extensive. Most of them are
worked underground and reached by inclined tunnels. The first oper-
ation is to pick a horizontal space several inches high at the roof. Vertical
cuts are made with hand saws having one handle. After blocks are
broken loose at the base they are drawn out with powerful cranes,
squared with ax or saw, loaded on low tram cars, and hauled through

308 THE STONE INDUSTRIES

tunnels to the surface with horses or cable hoists. Excavations are very
extensive; it is claimed that some larger companies have no less than
60 miles of tunnels. Squared blocks weigh 6 to 10 tons each. The stone
is hauled by railway cars to docks at Bristol and Avonmouth for shipment
by water. Like Indiana limestone, the Bath stone will suffer from frost
action if not first seasoned. Work is continued underground throughout
the year, but in winter blocks are stored in headings that have been
worked out. They are brought to the surface about April and piled in
storage yards or shipped to customers. Before the World War Bath stone
was sawed into slabs by hand, but the requirements of that period
necessitated installing machines to conserve labor. Gang saws are used
for subdividing into slabs and circular saws for crosscuts. Since the
war large quantities of Bath stone have been cut to standard sizes, 63 ^
by 41^ inches, and in lengths ranging from 9 inches to 2 feet 3 inches.
Such sizes are laid by bricklayers and sold in competition with brick.
Houses made of them are much less expensive than cut-stone struc-
tures. Carefully selected Bath stone is durable in the British climate.
For centuries it has been used for most of the beautiful ecclesiastical struc-
tures of western England, including the Abbey Church of Bath, Glaston-
bury Abbey Church built in the eleventh century, and Wells Cathedral
begun in the twelfth century, all of which are still well-preserved.
Bath stone sometimes is imported into the United States in considerable
quantities and sold through New York dealers. It has been used for
interiors and exteriors of many large buildings.

Portland stone ranks next to Bath stone in commercial importance.
The name is derived from Portland Island on the Dorset coast, where the
chief quarries are situated. It is harder and less uniform in texture than
Bath stone and better adapted for the more massive Italian architecture.
It was a favorite material employed by Sir Christopher Wren and other
architects for rebuilding London after the great fire of 1666. Sir Chris-
topher controlled the Portland quarries during the construction of St.
Paul's Cathedral, begun in 1675. The harder and more durable stone
comprises the Whit bed; and the Best, or Base bed contains material
suitable for fine carving and interior work. An overlying bed, known as
the " Purbeck-Portland" stone, has been mined underground for many
centuries. A section of the Whit bed 1}^ to 4 feet thick, known as
"Perricot" stone, is crystalline and unusually fossiliferous. It is
particularly adaptable for the manufacture of highly polished interior-
decorative slabs.

The first hydraulic cement manufactured in England, when mixed
with water and allowed to set, formed a massive rocklike substance closely
resembling Portland stone. For this reason it was called "Portland
cement," a name which has been retained in England and in
America.

FOREIGN BUILDING AND ORNAMENTAL STONES 309

A ferruginous limestone known as "Horton stone" is quarried for
building purposes at Edgehill, Warwickshire. Another important center
is about 12 miles from Salisbury, where the Chilmark siliceous limestone
is still being mined for building purposes, chiefly in Winchester. This
stone was used for the construction of Salisbury Cathedral, erected about
700 years ago.

A white limestone in beds totaling 113-^ feet in thickness has been
worked underground for centuries at Beer on the south coast of 'Devon-
shire. "Beer" stone was used in Exeter Cathedral and many other
notable structures but during recent years has been worked on only a
small scale.

A 4-foot bed of cream oolitic limestone is quarried for building at
Ketton, southeastern Rutland County. It was used in the construction
of the Cathedral of Ely, the Cathedral of Peterborough, and many other
ancient and modern buildings. The quarries first were opened under
Royal charter in 1301. Similar oolitic limestone quarried near Clipsham,
northern Rutland County, has been used quite extensively for restoring
the Houses of Parliament and various cathedrals. A creamy oolitic
limestone has been quarried for many centuries at Weldon, Northampton,
a few miles south of the Rutland County quarries. Kirby Hall, bearing
the date 1593, was built of this stone.

FOREIGN SANDSTONES

Canada. — Potsdam-Beekmantown sandstones of Cambrian age occur
in southern Ontario and have attained some importance in the Ottawa
district. White, brown, and yellow stones have been used for such
notable structures as the Parliament Buildings, the Museum, and the
Archives Building. Medina sandstone occurs in Ontario in a bed
averaging about 12 feet in thickness, which outcrops along the Niagara
escarpment from near Niagara Falls through Hamilton, Credit Forks, and
Orangeville to Shelburne. It appears in three chief colors, brown, gray,
and mottled. Brown stone from the Credit Forks district is of the
highest quality and was used to construct the Parliament Buildings and
many other edifices in Toronto. Virtual cessation of quarrying is due
largely to difficulty of working steep outcrops that have a heavy over-
burden of Niagara limestone.

The Permo-Carboniferous and the Millstone Grit of Middle Carbonif-
erous age have supplied olive green, gray, red, and brown sandstones for
local use in many parts of the Maritime Provinces. The Paskapoo
formation of Eocene age furnishes the best building stone in the Prairie
Provinces, except for the Tyndall limestone. It is soft, easily worked, and
occurs in a variety of colors which have made it an attractive stone for
use in Edmonton, Calgary, and other cities. It is quarried principally

310 THE STONE INDUSTRIES

near Calgary and at various points north and south along the line of the
Canadian Pacific Railway.

Other Canadian sandstones worthy of mention are the "Sillery,"
which was used extensively in construction of the citadel of Quebec, and
the blue to buff "Cowichan," quarried on Gabriola and Saturna Islands,
British Columbia, for buildings in Victoria and Vancouver.

France. — Sandstones are widespread in France, having been worked
in at least 36 Departments, but they are employed mainly for local use.
The more important quarries are in the Triassic and Tertiary formations;
for many centuries these have furnished stone for constructing bridges,
churches, canals, fortifications, and pavements. As means of trans-
portation have improved many less desirable quarries have been aban-
doned in favor of better stone obtainable at more distant points. The
industry has little international importance.

British Isles.^ — The "Old Red" sandstone of Devonian age is quarried
extensively in England and Scotland. A deposit in England bordering
South Wales supplied stone for such notable structures as Tintern Abbey,
built in the thirteenth century and still well-preserved. In Scotland
the largest areas extend from Moray Firth to the Orkney Islands in the
north and from Dumbarton northeast to Stonehaven in the south-central
region. The stone has been used locally and also shipped in large
quantities to London and other English cities for building stone, trim,
flagging, and curbing. The famous Caithness flagstone of northern
Scotland has provided much of this material.

Lower Carboniferous sandstones occur in northern England and
southern Scotland. Quarries in Northumberland were worked by the
Romans to build the piers of a bridge over the North Tyne about A. D.
120; the piers are still in good condition. The same formation, quarried
extensively on both sides of the Clyde and the Forth, furnishes some of
Scotland's finest building stone. The architecture of Edinburgh and
Glasgow has been influenced by sandstone in much the same way as that
of Aberdeen has been dominated by granite.

The Millstone Grit of Carboniferous age, occurring in Derby, Lan-
cashire, Newcastle, and Northumberland, provides a coarse-grained
massive stone suitable for heavy foundations, piers, and docks and a
finer-grained variety for superstructures and trim. Coal Measures
sandstone lying above the Millstone Grit has been used widely in and
about Bradford, York; Nelson, East Lancashire; Durham; and North-
umberland. Permian sandstones in Devon, Shropshire, and Cumberland
furnish some good building stone.

The Triassic, known as "New Red" sandstones, are distributed widely
over central and northwestern England. Stone quarried on the cliffs
at St. Bees Head near Whitehaven, northwestern England, was used for
Washington's home at Mount Vernon. Red Triassic sandstones have

FOREIGN BUILDING AND ORNAMENTAL STONES 311

been quarried extensively in Cheshire. The famous Warwick Castle was
built of this stone, and similar sandstone is found in many buildings in
Liverpool, Old Chester, and other cities of that region.

New Red sandstone of high quality, occurring in Dumfries and Ayr,
southern Scotland, has been used widely in the British Isles and exported
to the United States, Canada, and other countries. Much of that shipped
to America is bright red stone from near Thornhill and Annan, Dumfries.
It has been used in the interior of the State Capitol in Albany, the
American Fire Insurance Building in Baltimore, and the Telephone and
Telegraph Building in Boston.

Africa. — Sandstones abound in the Union of South Africa and are
quarried for local use in many places. Among the most widely used are
the Table Mountain sandstone at Nieuwoudtville and Cape Town, Cape
of Good Hope, and the Karroo sandstone at Steenpan, Flatpan, and
Ladybrand, Orange Free State. Coal Measures sandstone is quarried
at many points in the Transvaal.

FOREIGN GRANITES

Canada. — Probably no country in the world exceeds Canada in extent
of granitic rocks. The great Archean shield, consisting chiefly of granite
and gneiss, extends from the Great Lakes northeast to the wilds of
Labrador, northwest to the Yukon, and, except for the interruption of a
small sedimentary area near Hudson Bay, north for an unknown distance
into the Arctic regions. All but an infinitesimal part is either unsuited
for dimension stone or is beyond economic reach of markets. Com-
mercial development has been confined to easily accessible parts or to
outlying areas near centers of population.

Ontarno. — An attractive red granite has been quarried near Kingston,
Ontario, but its close jointing causes much waste which makes it
difficult to compete with stone imported from Aberdeen, Scotland.
Granites abound in the Thousand Islands district, but inability to
obtain large blocks without excessive waste discourages production,
except for paving blocks. Stone for rough construction is quarried near
Parry Sound.

Maritime Provinces. — The most important granite area in the Mari-
time Provinces is near the town of St. George, Charlotte County, New
Brunswick. The best stone from this district is a coarse-grained red
granite suitable for monuments and decorative building. Pink and
light gray varieties are also obtained. Numerous small quarries have
supplied blocks to finishing mills in St. George. West of St. John River
opposite Spoon Island pink and gray monumental and building granites
have been quarried for many years. A gray building variety is obtained
from boulders near McAdam Junction, New Brunswick. Near West
Nictaux, Annapolis County, Nova Scotia, a fine-grained gray monu-

312 THE STONE INDUSTRIES

mental and building granite is quarried, but excessive jointing is a
serious obstacle to extensive development. A coarse-grained gray
variety, used in many large buildings in Halifax and Sydney, has been
quarried near the eastern edge of a great granite mass stretching westward
from the harbor of Halifax, Nova Scotia. Black granite (diabase) is
available in several areas but has been little worked ; activity is in prospect
near Loch Katrine. An undeveloped reddish and variegated felsite-
breccia commercially related to granite occurs on Scatari Island, Cape
Breton County, Nova Scotia. It is attractive, takes a good polish, and is
available in pieces large enough for clock cases, statuettes, fireplace tile,
and novelties.

Quebec. — Coarse-grained granites of pre-Cambrian age are quarried in
Quebec at Riviere a Pierre, Portneuf County; Roberval, Lake St. John
County; Brownsburg, Argenteuil County; and in Ottawa County. They
are used principally as building stone and for paving blocks. The most
important producing area for building granite in Canada is in Stanstead
County near the United States border. The rock is a medium-grained
light gray intrusive granite of later age than surrounding sediments.
It has been employed for many buildings in Montreal, Toronto, Ottawa,
and other eastern cities, and some has been shipped to the Prairie
Provinces. Well-equipped mills are maintained for sawing, dressing,
polishing, and cutting into columns. At Mount Johnson 6 miles east
of St. John fine-, medium-, and coarse-grained black granites (diabases or
diorites) are obtained. One variety is marketed as monumental stone
under the trade name "Canadian Quincy."

Western Provinces. — In the Prairie Provinces the only granite now
of any importance is a dark, variable colored, medium- to coarse-grained
rock of pre-Cambrian age occurring east of Lake Winnipeg, Manitoba,
and used to a limited extent for rough building. British Columbia has
an abundance and variety of granitic rocks. Gray to pale pink granite
of pre-Cambrian age has been quarried in a small way near Lake Okan-
agan for buildings and monuments. The great Coast Range, extending
850 miles along the coast, consists of a variety of igneous rocks ranging in
composition from true granites through granodiorites to more basic
types, such as gabbro. They furnish the most important building and
monumental stones of the Province. The best-known commercial stone
is a gray granodiorite of the Jervis Inlet area quarried on Nelson, Hardy,
Fox, and Granite Islands and used for many important buildnigs in
Vancouver and Victoria. An extensive occurrence of gray granodiorite
near Nelson has been worked for building stone in several localities.
An attractive gray andesite suitable for building stone has been obtained
on Haddington Island.

Scotland. — "Scotch granite" is a familiar term among stone dealers
and users because granites from Aberdeen and Peterhead were the first

FOREIGN BUILDING AND ORNAMENTAL STONES 313

to enter international trade extensively. Wide use throughout Great
Britain led to their introduction into the United States by early settlers
of British extraction; thus, they became firmly established as standard
memorial stones in America. Aberdeen granite is gray to light blue and of
fine to medium texture. Peterhead granite, quarried north of Aberdeen,
is prevailingly red and polishes well. The Aberdeen industry began
about 300 years ago, and many quarries worked downward 200 to 300
feet are so deep and narrow that they have been abandoned. Com-
pressed air was first used for drilling in 1899. The stone has been used
widely for monuments, buildings, locks and harbors, and paving. The
paving industry was at one time very important but has declined greatly
with the substitution of other types of street and highway construction.
Aberdeen, known as the Granite City, is built largely of stone from
near-by quarries. It has become so important as a marketing center
that granites from other parts of Scotland and from the Scandinavian
countries are marketed through it and are sometimes sold as Aberdeen
granites.

Curbing, building stone, and monumental granite are produced at
Creetown, Kirkcudbright County. The quarries have produced steadily
for a hundred years.

Ireland. — A great variety of granites occurs in Ireland; they have been
worked in many places, particularly in Dublin, Wicklow, and Wexford
Counties. Gray and red granites that take a good polish are abundant,
but production has been spasmodic, and no export trade of importance
has developed. They have been used widely for local building and
paving for many centuries.

England. — The most important commercial granites of England occur
in Cornwall and Devon. Granite was used as early as 1756 for the
exterior of Eddystone Lighthouse. The Devon rock is gray, somewhat
porphyritic, and better adapted for heavy masonry than for decorative
purposes. It was used in London Bridge and many other massive
structures. Silver-gray granite is plentiful in Cornwall. It is quarried
chiefly at Boslymon and Carne for curbing and heavy masonry. The
Cornish granite industry normally employs about 2,600 men. At Shap,
Westmoreland County, a very attractive porphyritic granite with flesh-
colored orthoclase crystals is produced for decorative and building pur-
poses, and some is shipped to the United States. Granites from Scotland
and elsewhere are finished in well-equipped shops in this district. At
Mount Sorrel, Leicester, a gray to light reddish brown variety (grano-
diorite) is quarried for monumental work. Diorite quarried at Nun-
eaton, Warwickshire, is manufactured into curbing, paving blocks (setts),
and other products.

Norway. — Granite has long been used in Norway, but only since 1876
has production become important through development of a large export

314 THE STONE INDUSTRIES

trade. A small area in the southern part of the country near the Swedish
frontier produces 70 to 80 per cent of the total output. A very beautiful
gray syenite quarried at Laurvik has no counterpart in America. It
contains tabular, iridescent crystals of plagioclase (Laurvikite) which
present a striking display of colors on polished surfaces. It is marketed
as ''Norwegian Pearl Gray" for interior and exterior decoration. A
notable example is to be found in the exterior lower courses of the Chrysler
Building in New York. Another Norwegian syenite (Nordmarkite),
composed principally of red microperthite, occupies a large area north of
Christiania and is used for house construction in and about that city.
Many quarries are near the seashore, where overburden has been removed
by glacial action. The advantages of availability and transportation by
water enable Norwegian producers to compete successfully in foreign
markets of Europe and America.

Sweden. — Prior to 1350, 94 churches on the island of Gotland were
built of granite quarried on the island. Granite was first used in quantity
for building purposes on the mainland of Sweden in the sixteenth century.
About the middle of the seventeenth century brick became a popular
building material, and stone quarries were neglected for nearly 100 years,
but the granite industry was reestablished during the canal-construction
period of the eighteenth century.

Red and other ornamental granites, such as "Swedish Rose," are
popular for polished monumental w^ork at home and abroad. Building
stone is also exported; a notable example of its use is in the Peace Palace
at The Hague. While the entire coast of Sweden from Halland north
to the Norwegian boundary is a continuous stretch of granitic rock,
greatest development has been in the Goteborg district at the north
where the rock is not only of excellent quality, but splitting properties
are exceptionally well-developed. However, some important quarries
are worked in the southern area in the Province of Halland.

An extensive deposit of gabbro, known to the trade as black
granite, occurs in the Province of Jonkoping and is obtained chiefly
from the Herrstad quarries. Large quantities are shipped in rough
blocks to New York, where it is used extensively for building and manu-
factured into monuments which are sold principally in the New York
area. Some rough blocks of Swedish black granite are manufactured
into finished dies in Germany for export to the United States.

Paving blocks are an important part of the granite production of
Sweden, as the export market was developed primarily for their disposal.
The chief center of the industry is on the western coast in the Goteborg
district where the rock has an excellent rift and run. Stones are sub-
divided very rapidly with splitting machines into small sizes, 3 to 4 inches
in diameter, known as durex blocks; milHons have been shipped to
Argentina, North America, and Australia, The small blocks are pref-

FOREIGN BUILDING AND ORNAMENTAL STONES 315

erable for long-distance shipment as the weight of small stones required
for a square yard of paving is little more than half that of ordinary paving
blocks.

In the early development of the industry quarries were operated
in a crude way by a large number of small landowners, but of late years
they have been concentrated in the hands of a few large companies and
have been modernized. Further stabilization was accomplished in 1929
when a working agreement in the nature of a cartel for control of produc-
tion and marketing was reached among the principal Swedish and
Norwegian quarry owners. This agreement covers production of paving
stones and block granite.

From 90 to 95 per cent of the granite produced in Sweden is exported,
about 50 per cent to Germany, 11 per cent to Czechoslovakia, 11 per cent
to the United States, and 10 per cent to Great Britain.

Finland. — Finland is the most important source of foreign monu-
mental granite for the United States. Granite shipped from Finland
to the United States in 1931 was valued at about $120,000 and in 1937
about $187,000. These amounts were, respectively, about 50 and 76 per
cent of the total value of granite imports. Red, gray, and black varieties
are quarried in many places on the mainland and on islands in the Baltic
Sea. The red type figures most prominently in foreign trade and com-
prises nearly all that exported to the United States. Much of it is shipped
to Scotland, where it is manufactured and exported as "Red Balmoral,"
which sometimes passes as a Scottish granite. Other varieties include
"Birkhall," a gray rock, ''Russian Blue," and a black type obtained
in smaller amounts. A granite of striking appearance, known as
"Rapakivi," contains large, red, orthoclase crystals, some several inches
in diameter. Paving and curbing production, though still important, has
declined to some extent.

France. — Granite is distributed widely in France, the Paris Basin in
the north-central part being the only large area without some granitic
rock. It is now, or has been, quarried in more than 30 Departments. A
great variety of attractive material is available, but very limited quan-
tities are sold outside domestic markets. Gray granite from Vire in the
Department of Calvados has been worked extensively for architectural
uses, and some has been exported. Blue, blue-gray, rose, and red stones
from coarse to fine in texture have been quarried at Finisterre in north-
western France for building piers, docks, bridges, lighthouses, and
churches. Many granites, chiefly gray and bluish gray, have been
obtained in the Department of Manche for military works, harbors,
churches, and numerous other structures. Other igneous rocks such as
tuffs and volcanic lavas, are used for local building.

Germany. — Large granite quarries and finishing plants are operated
in Saxony and Bavaria, but production costs are high. The mills are

316 THE STONE INDUSTRIES

well-equipped with modern machinery, but the quarries are worked in
crude fashion. As noted in previous pages, German stone mills obtain
large supplies of rough blocks from foreign countries, particularly
Sweden. Finished granite is exported from Dresden to the United
States. Many basalt paving stones are manufactured in western
Germany,

Italy. — The chief granites of Italy occur along the west bank of
Lake Maggiore about 100 kilometers from Milan. Stone in various
shades of red, capable of fine polish, is well-adapted for architectural uses
and has been used in cathedrals and other buildings in Milan and Rome.
Some has been exported to the United States and South America.

Switzerland. — The largest deposits of granite in Switzerland are found
in the Cantons of Uri, Graubunden, and Tessin, greatest activity being
centered in the last. Both building and monumental types are produced.

Egypt. — A coarse-grained, reddish hornblende granite, the ancient
"Syene," occurs in extensive deposits along the Nile River near the
town of Assouan. Thus originated the term "syenite," although in
modern usage the Syene rock which contains much free quartz is not a
true syenite. The Egyptian rock was quarried as early as 1300 B.C. and
used for innumerable obelisks, columns, and statues. The obelisks have
suffered very little deterioration in the mild, uniform climate of Egypt.
An interesting account of the methods of quarrying, transportation, and
erection of the obelisks has been published.'*^

South Africa. — Granites and related rocks of good quality are obtained
in the Transvaal. The best-known varieties are the Bon-Accord
norite, which is quarried about 8 miles north of Pretoria for building
and monumental uses; the Leeuwfontein red syenite from near Hatherley;
and the Pietersburg granite about 4 miles south of Pietersburg. The
first and third varieties are now generally used.

FOREIGN MARBLES

Since ancient times marble, because of its attractiveness, workability,
susceptibility to polish, and infinite variation in color and texture, has
been a favorite material for sculpture and architecture. It commands
a price high enough to justify shipment for long distances, therefore that
of high quality can find markets in far-distant lands. Marbles are widely
distributed throughout the world, many are types that have no counter-
parts outside their restricted localities, and numerous varieties are used in
the United States; therefore important occurrences throughout the world
are of interest to American producers and consumers.

The following table shows imports of marble from leading countries
over a period of years. The figures compiled by the United States

■•2 Engelbach, R., The Problem of the Obelisks: Bruce Humphries, Boston, 1931,
134 pp.

FOREIGN BUILDING AND ORNAMENTAL STONES

317

Department of Commerce show total imports from the country from
which the material was last shipped, which is not necessarily the country
of origin. For example, some of the stone imported from Belgium is
French and Italian marble which has been manufactured into finished
products in Belgian mills.

Value of Marble Imported into the United States, 1928-1937,
BY Countries

1928

1929

1930

1931

1932

Belgium

France

Germany

Greece

Italy

Spain

United Kingdom

Canada

Mexico

Belgium

France

Germany

Greece

Italy

Spain

United Kingdom.

Canada

Mexico

Argentina

\ 169,692

283,553

131,620

73,840

1,593,096

26,807

14,009

769

97,969

; 209,820

420,405

129,891

47,178

1,418,519

47,072

25,721

22,028

78,166

410,295

370,920

133,691

71,989

,023,435

47,654

30,304

1,466

69,844

$130,001

142,214

71,535

11,543

454,119

21,275

12,397

129

12,069

$ 58,331

34,566

25,648

2,957

245,612

7,491

5,613

1,355

1933

1934

1935

1936

1937

34,340

17,352

7,080

105

132,211

22,047

6,472

5,101

54,306

20,047

14,944

1,573

70,752
3,868
2,410
2,418
5,862

58,990

26,148

34,057

2,563

1,948

95,011

4,391

9,966

20,743

94,378

\ 54
24

150
1
5

72,

062
488
503
13
217
290
245
648
581
091

$ 76,753

43,505

2,620

142,636

4,076

1,469

56,962

75,840

Canada. — Marble has never been an important Canadian product,
and the greater part of that produced is for local use only. Most of the
few quarries operated are in the Province of Quebec.

Numerous occurrences have been noted in the crystalline area of
southeastern Ontario, and though very Httle marble has been produced,
reference may be made to some commercial types. "Arnprior," from
Renfrew County, was used in the Parliament Buildings at Ottawa.
"Cipollino Green" is a dark green, brecciated marble with occasional
lighter spots and streaks. "Lanark Serpentine" is another type of green
marble. "Rose Fantasia," from Hastings County, is a highly colored
rock showing patches of bright red, salmon, and other colors embedded
in a micaceous matrix. Crystalline limestones occur in various places
in the Maritime Provinces, but no production of decorative stone is
reported.

318 THE STONE INDUSTRIES

Attractive marbles are obtained near South Stukely in eastern
Quebec, and rough blocks are shipped to a finishing mill at Montreal.
The chief commercial types are " Jaune Royal/' a light cream rock shot
with greenish yellow veins and markings, and "Violette," which has a
white background intersected with violet and green veins. High-quality
marbles are produced also at Phillipsburg in the Missiquoi area, Quebec.
"Rose Vert" has a green base with patches of mottled white and rose,
some as large as 2 inches in diameter. "Vert Gris" has a grayish base
traversed by fine, green lines. The quarry and mill at Phillipsburg are
well-equipped. Attractive green serpentines occur at Orford Mountain,
Quebec, but have not been developed.

Marbles of three general types occur in British Columbia — banded,
reddish crinoidal, and pink and white dolomitic varieties. Commercial
development is confined to the Kootenay quarries near Marblehead in
rock of the first type, but production has been very small. Typical
''Kootenay" is light gray with dark gray bands.

Cuba. — Several hundred tons of sawed marble a year are shipped from
Nueva Gerona, Isle of Pines, to Cuba for use in Havana and other
places on the island.

Italy. — Far back in the days of the Roman Empire the abundance and
excellence of Carrara marble made Italy a world center of art and archi-
tecture as well as of marble production, and throughout succeeding years
the name "Italy" has been associated with beautiful statues, monuments,
and buildings wrought in that enduring stone. The country's supremacy
in marble production was never challenged until recent years, when the
United States became the chief producer and France assumed the lead in
number of varieties. The most prominent Italian marbles reaching the
American market are the white "Carrara," the yellow "Siena," and the
colored varieties from Verona. Until recently about 80 per cent of all
marble imports into the United States originated in Italy, but a much
smaller proportion is now obtained from that source.

Carrara. — The Carrara marble district lies between Genoa and Pisa
in the Carrara Mountains — a rugged range of the Apuan Alps reaching a
height of 6,000 feet within a few miles of the sea. These mountains,
which are regarded as of Triassic age, are in two parts, constituting a
branching anticline. The initial thrust that caused intensive folding
was from the southwest or Mediterranean side, where the slopes are
about 45°. On the opposite or land side they average about 20°. The
Carrara marble zone proper covers an area of about 64 square miles, and
the chief quarries are on the steep seaward-facing slopes.

Marble classed as Carrara comes from four districts: Carrara proper
furnishes about two thirds of the total production; Versilia, about 17
per cent; Massa, 10 per cent; and Garfagnana, about 6 per cent. Propor-
tions, however, vary somewhat from year to year. The marbles may be

FOREIGN BUILDING AND ORNAMENTAL STONES 319

divided into three general groups — statuary, ordinary white, and colored.
Roughly, about 10 per cent is of statuary grade; 75 per cent ordinary
white; and 15 per cent colored and brecciated varieties.

Qualities that have made statuary marbles famous are fine grain,
which lends itself admirably to the sculptor's chisel, pure white or creamy
color, and translucence. They are divided into two classes, a pure white
to cream, adapted for the best statuary work, and a bluish white decora-
tive stone. The finest statuary marbles appear in comparatively small
masses which occur to some extent in all the principal quarries. The
principal statuary marble quarries are the Altissimo, Fondone and Gobie
at Seravezza in the Versilia district. Except in the lower zones the masses
occur within the ordinary white marble and gradually merge with it.

The ordinary white marbles are used principally for monuments.
According to one classification they are subdivided into "Pavonazzo,"
cream with green and yellow markings; "Cipolin," with greenish mark-
ings similar to those found in Greek marbles of the same name; "Ara-
bescato," with a network of veins; and "Calacata," a white marble with
faint yellow streaks. Many special names are given to products of
individual quarries. They are known as Sicilian marbles in England,
because at one time they were shipped by way of Sicily.

The colored marbles are highly prized for decorative purposes. Some
of the more important are "Bardiglio," from Seravezza, pale dove
traversed with dark veins; "Breche de Seravezza," and other brecciated
marbles; a greenish-white Cipohn marble known as "Pietra di Volegna,"
quarried near Pietrasanta; "Rosso Antico," which is deep red and
"Viola Antico," which is purple.

The Carrara quarries first were worked by the Romans about 283
B.C. Marble suddenly became very popular in Rome about 27 B.C.,
for the Emperor Augustus boasted that he found Rome a city of brick
and would leave a city of marble. The industry languished after the
downfall of the Roman Empire but gradually assumed importance as
marble became employed more widely throughout the civilized world.
Periods of depression have been occasioned by various wars, but Carrara
still maintains an important place among marble-producing districts.
Several hundred quarries are operated, and normal annual production
exceeds a half million metric tons.

Slow hand methods were used to separate quarry blocks before the
invention of gunpowder. Thereafter explosives often were employed in
sufficient quantity to start loosened blocks sliding down the steep
mountain side. The rapid descent and powder blasts together caused
excessive waste. Channeling machines have not found favor in Carrara,
but for many years wire saws have been used successfully. It is claimed
that the wire cuts marble somewhat more slowly than it does Tivoli
travertine, in which the average cutting rate is about 5.4 square feet an

320 THE STONE INDUSTRIES

hour. Both single and double helicoidal wires are used, the latter
having the twist reversed about every 25 meters. Cuts are made at
almost all angles; some are nearly horizontal. Front and side joints
are utilized to advantage.

One of the most serious quarrying problems is the enormous quantity
of waste that has accumulated for many centuries. In early days only
the most accessible blocks close to the surface were removed, and waste
from new openings covered the remaining beds. Waste piles, locally
called "rivers of marble," form one of the most conspicuous features of
the Carrara Mountains (see fig. 63). Waste is now carried beyond the
limits of future operations, but accumulations of the past are so great

Fig. 63. — General view of the Carrara, Italy, marble district, showiiiK enormous piles of
waste. {Courtesy of J, B. Newsom.)

in many places that economical removal seems impossible. Since the
wire saw was introduced in 1895 waste has been reduced greatly.

Large quarry blocks trimmed and squared with wire saws, hand tools,
and hammers are fastened on sledges and taken down the steep mountain
side on skidways by special gangs of men known as "lizzatori," or
"sliders" (see fig. 64). Soap or oil is put on the skids, and blocks are let
down by heavy ropes snubbed to trees or posts along the way. On the
north side of Mount Sagro blocks weighing as much as 5 tons are brought
down with an overhead cableway. A new rope tramway of 20-ton
capacity has recently been completed. It is said to be the largest of its
kind in the world, having a span about a mile long as well as several
shorter spans.

Marble for export is conveyed from the landing at the foot of the steep
slope to the seaports of Avenza and Marina di Carrara by means of the

FOREIGN BUILDING AND ORNAMENTAL STONES

321

marble railway (Ferrovia Marmifera). No single event gave greater
impetus to the industry than did this railway, completed in 1890 with a
total length of 15 miles, including branches.

Over 100 mills are operated at Carrara for sawing blocks into slabs.
Three methods are followed. The first and crudest is with an implement
somewhat Hke a common buck saw, though larger, worked by two men;
the second and most common is by use of an ordinary gang saw driven by
water power, electricity, or steam, sand being used as abrasive; the third
method is wire sawing.

f!vr..-^

^^.^.-m> ^

Fig. 64. — Dragging a marble block on greased skids, Carrara, Italy. {Courtesy of J. B.

Newsom.)

Studios constitute an important feature of the industry. Art in
marble working was inspired in the fifteenth century by Michael Angelo,
who went personally to the Carrara quarries to obtain blocks for most of
his masterpieces. In 1769 Maria Theresa founded the Academy of Fine
Arts in Carrara, where many celebrated artists received their early train-
ing. Hundreds of little studios or shops are now occupied by men and
boys carving ornaments, statuary, and architectural units.

In December 1927 a consortium was established by royal decree under
the official title, "II Consorzio per ITndustria e il Commercio dei Marmi
di Carrara." It constituted Government control of rough and sawed
marble produced in and about Carrara; the aims were to modernize
production, facilitate execution of orders, reduce costs, and promote
sales in Italy and abroad.

Other Italian Marbles. — Next to Carrara " Siena" probably is the most
popular foreign marble in the American market. The deposit is high in
the mountains about three hours' ride from Siena, which is in central

322

THE STONE INDUSTRIES

Italy between Florence and Rome, Quarries are small and crudely
worked. Blocks are separated laboriously, handled with windlasses and
screw jacks in the absence of derricks, rolled down the hill to the road-
way, and transported by ox teams to the railway at Empoli about 15
miles away (see fig. 65). Material for export is shipped from Leghorn.
The largest quarry, the Convent, produces the highest-priced marble,
"Brocatello di Siena" a deep yellow with purple to almost black veins.
When the purple veins predominate it is known as "Paonazzo di Siena."
Among the most familiar varieties are rich yellow with veins and mot-
tlings of white, pearl gray with yellow veins ("Gray Siena"), and bright
yellow with scarcely any markings ("Siena Unie"). They are used prin-

FiG. 65. — A picturesque method of hauling marble in Italy. {^Courtesy of J. B. Newsom.)

cipally for interior decoration, alone or in combination with other types.
About 3,000 metric tons are quarried a year and approximately two
thirds is exported. No similar marbles are produced in America, though
yellow varieties from France and Algeria are competitors.

Verona and Vicenza colored marbles are obtained from at least 200
quarries, many being underground workings which have supplied stone
for the magnificant palaces and public buildings of Venice, Vienna,
Budapest, and other cities. Notable varieties are "Verona Red";
"Giallo" (yellow); "Del Torri"; "Brocatello," one of the fossiliferous
types; and "Bianco," white with a few light veins, the best known in the
markets. With the annexation of Istria in 1919 Italy acquired the valu-
able quarries of Aurisina, which were worked by the Romans. The
marble of this district takes a high polish and is well-adapted to resist
weathering. "Botticino," obtained near Brescia, a light cream marble

FOREIGN BUILDING AND ORNAMENTAL STONES 323

with slender brown markings, is popular in the United States. The
interior of the Grand Central Terminal in New York is an example.

Notable among the Ligurian marbles quarried near the Gulf of Spezia
are "Rosso di Levanto," deep red; "Levanto," ranging from purple to
red, with dark green serpentine veins; and "Portor," black with gold
markings and known in England as "Black and Gold." The best-known
Lombardy marbles are the pink and gray, from Val Seriana, and the
"Rosso Antico," of Val Brembana. The latter shows a striking combina-
tion of blood red, ebony black, gray, dove, and pink. Black marbles are
also obtained in this region. Among the Piedmont marbles are "Verde
delle Alpi," having a pleasing green-blue color, and "Alpine Black,"
very little of which enters foreign trade. Umbrian marble was used
extensively in decorating the interior of St. Peter's in Rome, Serpentine
marbles are obtained at Prato near Florence. Many beautiful marbles
are quarried at Abruzzi, Apulia, Calabria, Sicily, and other points in
southern Italy, but most of them are used locally only.

France. — France surpasses all other countries in number of varieties of
marble produced. In 1888 Blagore^^ listed 240, and since that date
many new types have been placed on the market. The color range
includes white, black, gray, green, red, brown, and yellow, with striking
combinations of two or more colors.

Like the marble industry of Italy that of France dates back to the
period when Gaul was a Roman province. Gallic marbles were used for
local building and transported to Rome to aid in the decoration of
many beautiful structures. Native marbles were employed extensively
in France throughout the Medieval Period, the Renaissance, and partic-
ularly the reign of Louis XIV, for churches, palaces, mansions, and
public buildings. The industry languished in the early years of the
Republic until 1835, when it became more active and flourished to the
World War in 1914.

Although France produces an abundance and variety of marbles her
export trade has been less extensive than that of Italy as the material is
used very widely at home. However, during the past few years exports
to America have increased materially.

The more important French marbles entering international trade
include "Sarancolin," obtained in Hautes-Pyrenees and first quarried in
the reign of Louis XIV, a banded and mottled brecciated marble highly
esteemed for monuments and interior decoration. Different varieties
show combinations of gray, yellow, red, white, and brown in veins and
patches. One type of prevailing red with dove patches has been used
extensively in Paris, notably for massive decorative columns, " Campan,"
also quarried in Hautes-Pyr^nees near Bagneres, is used for furniture and
interior decoration. Several varieties occur in combinations of rose,

*^ Blagore, G. H., Marble Decoration. Crosby, Lockwood and Son, London, 1888.

324 THE STONE INDUSTRIES

green ("Campan Vert"), and red ("Campan Rouge"). "Griotte d'
Italie," obtained from quarries near Caunes and Felines in Herault, is a
high-priced decorative marble. It is one of the French marbles best-
known in England, where it is used with black for chimney pieces and
clock cases. It has a brown or dark red groundmass with cherry patches
and white spots. "Languedoc," quarried at Caunes, is fire red mixed
with white and gray. Under the name "Rouge Francais" it has been
accorded a place of honor among French marbles and used for notable
monumental architecture in France and Italy. "Napoleon," a light
fawn stone beautifully marked with pink and brown veins, "Lunel
Notre Dame," "Lunel Rubanne" and "Lunel Clair" are obtained from
large quarries near Boulogne in the Department of Calais. A company
organized in 1905 controls three quarries in the district, the Vallee-
Heureuse, the Basse-Normandie, and the Haut-Banc. Some marbles
of these quarries have beautiful flower like markings, hence the appella-
tion "Fleuri." The quarries are equipped with wire saws, hammer drills,
and other modern machinery. Wire saws are used also for cutting blocks
into slabs. Because of their proximity to Calais and Boulogne an
important export trade has been developed.

"Savoie Blue" and "Gilded Savoie," varieties of blue marble obtained
from deposits in Savoie, have become prominent during recent years.
"Hauteville" is a variety obtained from a rock classed as coral limestone
occurring in extensive beds in the Department of Ain. It is fine-grained,
is dense in texture, is of uniform light yellow, and takes a very high
polish, hence it is classed with decorative marbles. The rock is quarried
with wire saws and other modern equipment, and the products are
exported in large quantities to North and South America, Australia, and
Japan.

Brief generalized statements on the distribution of French marbles
by color may be of interest.

The best-known white statuary marble of France is the "Saint-Beat,"
quarried in Haute-Garonne. It is a uniform, pure, fine-grained stone,
obtainable in large, sound blocks. Many years ago it was carved into
statuary, vases, ornaments, tables, mantles, and similar articles at the
village of Saint Bertrand. White marbles were worked by the Romans
in 10 different localities in France, but except for the Saint-Beat none
attained prominence.

Black marbles occur in 13 Departments and mixed black and white in
8 Departments, but export trade in them is small. Those of deep black
have been quarried in Hautes-Alpes; in Doubs (a variety known as
"Le Grand Noir"); at Bize in Haute Garonne; and in various other
localities. Probably the best-known black and white marbles are "Le
Grand Diable" and "Le Petit Diable," quarried in Aude and at Aubert
in Ariege.

FOREIGN BUILDING AND ORNAMENTAL STONES 325

French marbles having characteristic red coloring occur in 19 Depart-
ments. "Rosso Antico," a blood-red stone with white veins and dots, is
a famous variety. "Griotte d'ltalie," mentioned previously, is well-
known. "Rose Eujugeraie," and "Sarrancolin de L' Quest" quarried
near Mayenne are among the most popular marbles of western France.
"Le Rouge Sanguin," "Le Grand Rouge," and a score of others might be
mentioned.

"Lumachelle" or shell marbles occur in 14 Departments. They
present a wide range of colors and patterns highly prized for furniture,
soda-fountain fronts, and interior decoration in England and America.
The many varieties are distinguished usually by a descriptive adjective
denoting color, for example, "Lumachelle Gris" and "Lumachelle
Jaune."

The Cipolin marbles, white with green stripes, are very attractive
for use in monumental architecture, interior decoration, and even for
statuary. They occur in at least three locahties in France, the "Cipolin
de Saint-Maurice" in Haute-Alpes; the "Corte Cipohn" in Corsica; and
the "Cipolin" in Isere. Both French and Italian Cipolin marbles are
well-known in American markets. Marbles from the south of France,
well-known during recent years in European and American markets,
include "Jaune de Brignoles," "Violetta de Brignoles," "Rose de
Brignoles," "Jaune Sainte Beaume," " Jaunes de Molignes," and "Breche
Orientale de Pour Cieux."

Many other w^ell-known marbles are quarried in France, but space will
not permit reference to them. The best-known varieties are listed in
Lent's glossary and in Watson's British and Foreign Marbles and Other
Foreign Stones, which are cited in the bibliography at the end of this
chapter.

Belgium. — Renwick'*^ makes the following interesting statement:
"The marble industry of Belgium is a practical illustration of how ener-
getic work and perseverance will enable a country that is far from rich in
a particular product to take hold of the material and make the trade
therein her own." The marble resources of Belgium are not great, but
they have been exploited advantageously, and some of the products,
notably the black varieties, have won worldwide reputation. Further-
more, Belgium has some of the largest and best-equipped marble-
fabricating plants in Europe, and at least one third of the raw materials
are obtained from France, Italy, and other countries. A large foreign
trade has been developed, particularly with Great Britain and the
United States.

** Renwick, W. G., Marble and Marble Working. Crosby Lockwood and Son,
London, 1909, p. 79.

326 THE STONE INDUSTRIES

The principal deposits are of Devonian and Carboniferous ages.
Many of the marbles are unsound and not attractive enough for highly
decorative uses; nevertheless, they are worked advantageously for small,
low-priced products, such as shop fittings, table tops, sanitary slabs, and
chimney pieces.

The most important deposits in Belgium are those producing "Belgian
Black" ("Noir Beige") which is regarded as the finest black marble in the
world. Four grades are handled — best, second best, common, and
inferior. The best grade is the pure deep black variety without veins or
markings. The finest grades are obtained northwest of Namur from beds
30 to 40 feet deep, incUned at an angle of 18° and extending about 8
miles. The formation is in layers a few inches to 4 feet thick separated
by shale. Rock of best quality is in the lower beds, and most of it is
obtained from underground workings. Black marble is also obtained at
Dinant in Namur near the French frontier and in other localities.

During recent years fossiliferous marbles have become popular in the
United States for soda fountains and other decorative uses. Examples
include ''Rouge de Ranee," with a reddish brown groundmass and large
white motthngs; and other reds, such as "Rouge Griotte Fleuri" and
"Rouge Byzantine Beige." The Rouge de Ranee quarries were reopened
in 1900 after being closed for nearly 200 years. Belgium has a great
variety of red marbles, which are as a rule sounder than most colored
varieties. The red and pink varieties are used extensively for decorative
purposes.

"Bleu Beige," quarried near Chatelet, Namur, and various other
localities, is a bluish black marble with fine white veins. The "St. Anne "
marbles are probably the best known, except for the black varieties,
and have the reputation of being among the soundest of the colored
marbles of Belgium. The highest quality, dark gray with white veinings
and spots, is produced near Biesme and Sougnies, two villages near
Charleroi. It occurs in a bed 60 feet wide and is worked at great depth.
A second type, lighter in color and with less-attractive veining, is quarried
at La Buissiere on the Sambre River.

"Petit Granit" is a variety of limestone described in the section
devoted to foreign limestones, but certain parts of the deposit, notably
those in the Ourthe Valley, are classed as marbles and are used for build-
ing in Belgium, France, Holland, and Germany.

Quarry methods and equipment in Belgium are among the most
efficient in Europe. Wire saws, compressed-air drills, and electric cranes
are widely utilized.

Spain. — Many varieties of marble occur in Spain. Beginning in the
north, micaceous rose marbles and others resembling the Cipolinos occur
in Galicia. They are available only in relatively small sizes. Green and
red marbles are obtained in Asturias. The latter, resembling French

FOREIGN BUILDING AND ORNAMENTAL STONES 327

Griotte, was used in such notable structures as the Cathedral of Leon and
the Royal Palace in Berlin. Important deposits of black, white, and red
marbles, some quite fossiliferous, occur in Guipuscoa and adjoining
Provinces. "Grand Antique de Biscaye " is obtained near San Sebastian ;
and "Estelle Black" and "Verde Molino" in Navarre.

A great variety of colored marbles occurs in the Province of Catalonia.
They were quarried extensively many years ago for cathedrals and other
important edifices. One, known to the trade as "Tortosa" and consist-
ing of numerous fossils in a red background, is fabricated into small
panels, mantelpieces, and clock cases. The Florido quarries, which
produce two shades, "Cream Florido" and "Rosa Florido," are among
the largest in Spain. They provide material for export to the United
States. Gray, red, black, and other varieties occurring near Toledo and
Molina in central Spain are used in Madrid and near-by cities.

"Rojo Alicante," and other red and yellow marbles of Valencia
and Alicante were worked in ancient times. Important deposits of
red fossiliferous marbles are quarried in Cordova and Granada for orna-
mental uses. Yellow, green, and other marbles from Malaga are of the
onyx variety, and some occur as stalactites.

An extensive deposit of coarse-grained white marble occurs in Almeria,
southeastern Spain. Production was confined to small workings until
1905, when a British firm began active quarrying. Manufactured
marble was shipped from Aguila to various Spanish cities for building.
There has been no recent activity.

Portugal. — There are two main centers of marble production in
Portugal — Villa Vicosa in the Province of Alemtejo, and Cintra Center,
north of Lisbon. "Rose Aurore" is the principal variety obtained in the
first district. Quite a variety of marbles are obtained from numerous
quarries north of Cintra in the second district. The chief commercial
types are "Lioz Bianco," "Lioz Rosa," "Fervenza," "Aimiscado,"
"Azulino de Maceira," "Vidraco," "Amarelo Negroes," and "Vermelho
dos Covoes." Marbles of lesser international importance are quarried
in other districts.

Switzerland. — The most important marble of Switzerland is the
"Cipolin," quarried at Saillon in the Canton of Valais. It usually con-
sists of a pale green groundmass with straight thin veins of deeper green,
but there are many variations. The highest quality, occurring in a bed
about 3 feet thick, is named "Grand Antique Cippolino." It takes a
good polish and is available in large sound blocks. It is popular in
Europe and America, where Greek Cipolin marbles are also used, but
little has been quarried since 1925.

Other important quarries are in the canton of Vaud. The St.
Triphon quarries of this district produce a black marble with gray and
white veining which is used for store fronts and table tops; white gray

328 THE STONE INDUSTRIES

and reddish brown stone which is easily worked and takes a good poUsh
is procured from other quarries. A variety known as "Villeneuve"
comes in hght and dark shades; the latter is much used for tombstones.
There were four important producing companies in 1922, two in Vaud
and two in Valais. Minor production is obtained from six other Cantons.

Greece. — The fine art of sculpture was developed to a high degree of
perfection by the ancient Greeks, whose classic masterpieces serve as
models to the present day. The art of carving statuary was no doubt
encouraged and promoted because of the availability of high-grade
marbles admirably adapted for shaping with tools. In ancient classical
Greek architecture marble even was used for roofing. The roof of the
Temple of Jupiter Panhellenius on the Island of Aegina and that of the
famous Temple of Diana at Ephesus are said to have been covered with
white marble tiles.

The most notable of the Grecian marbles are the ''Parian," obtained
on the Island of Paros in the Grecian Archipelago, and the "Pentelic,"
quarried on Mount Pentelicus near Athens. Parian marble, which occurs
in beds 5 to 15 feet thick, is of delicate, subtranslucent white, and is a
little coarser in grain than Carrara marble. With the opening of quarries
in the Carrara region the Greek industry practically ceased for 1,500
years. There have been several periods of renewed activity, but
present production is limited, the purest material being obtainable in
small blocks only. The Pentelic quarries were notable as a source of
material for the famous Parthenon erected under the supervision of
Phidias during the administration of Pericles, and dedicated in 438 B. C.
The quarries lapsed into disuse until 1834, and while they have at times
since that date produced large quantities recent production has been
moderate. Pentelic marble is of three grades — ordinary, for structural
uses; selected, for decoration; and the highest grade, classed as statuary.
"Rosso Antico," another famous Grecian marble, is one of the most
beautiful red marbles known. **Nero Antico" is a fine-grained black
marble widely used in ancient Rome. "Cipollino," a long-established
decorative marble, is exported to America. It consists of alternate bands
of white and pale green and was named because of its resemblance to an
onion cut in half. "Vert Tinos" is another green marble with white
zigzag veins. "Vert Antique," a brecciated green serpentine, is prob-
ably the original of all the numerous verde antiques quarried in America
and abroad, for it was used extensively in ancient Rome and Constan-
tinople. It occurs in three main types — light, dark, and intermediate.
"Skyros" appears in several forms; some are light-cream, with variable
veining; orange and bright-red veins characterize exceptionally attractive
types.

England. — Multicolored fossiliferous marbles of high quality are
quarried in Devon, principally at Ashburton, and considerable quanti-

FOREIGN BUILDING AND ORNAMENTAL STONES 329

ties are exported to the United States. The prevaiUng tints are pink,
gray, black, and red. The "Red Ogwell" quarry yields marble which in
richness of color surpasses many Continental products. Owing to
variations in color patterns, quite a variety of trade names is applied;
"Plymouth Dove," "Silver Gray," "Devon Siena," "Rose Red,"
"Spangled Pink," and " Favositidae " are examples. Large, sound
blocks are cut from the ledge with wire saws. The quarries are well-
equipped and maintain ample stocks. Large finishing mills are operated
at Torquay.

Derbyshire marbles, of Carboniferous age, are quarried at Wirks-
worth. The principal varieties are "Hopton-Wood," a white to gray
unicolored marble suitable for exterior building; "Bird's Eye"; and
"Derby Fossil." Among other marbles quarried in England reference
may be made to "Fosterley," a dark gray fossiliferous variety from
Durham; "Purbeck," a light green shell marble quarried near Swanage;
and several types in Sussex, Somerset, and Lancashire. A fine-grained,
light brown or variegated Carboniferous marble occurs near Beaumaris,
Anglesey, Wales; and a black marble, "Poolvash Black," on the Isle of
Man. Marble quarrying has not attained importance in England,
inactivity being attributed partly to the ready market availability of
Belgian and French marbles, and partly to relatively high railroad rates.

Ireland. — Black marbles from near Galway were at one time very
popular in London and in foreign countries, but the industry has declined
greatly. "Irish Black" is not a solid color; the most popular variety is
thickly studded with white shells. "Kilkenny" is another black,
decorative marble.

Increased activity has recently been noted in the "Connemara Green"
marble quarries near Clifden about 50 miles from Galway. The rock,
sometimes called "Galway Green," ranges from light yellowish to dark
green with occasional patches of purple and generally is beautifully
clouded, mottled, or veined. In the Lissoughter district, opened in 1878,
large sound blocks are obtainable, and it is reported that exports attained
some magnitude in 1928 and 1929. A red marble is quarried at
Shantallow.

Other marbles of a dozen or more district types have been quarried
at times in Ireland.

Other European Countries. — Several varieties of marble are obtained
in Germany, the best known of which are "Formosa," a multicolored
stone; "Green Poppenberg," a green-veined, fawn type; and "Bavarian
Green." According to a recent report, an onyx marble is quarried near
Gross-Giesen in Hanover for the manufacture of novelties. Fine-
grained fossiliferous marbles occur in Austria, particularly in the Tyrol.
Marbles are plentiful in Bulgaria. An ancient quarry at Trau, Yugo-
slavia, has been reopened to obtain stone for the Canadian Government

330 THE STONE INDUSTRIES

War Memorial at Vimy Ridge. White and light pink marbles are
obtained from well-equipped quarries in Rumania. Here both channel-
ing machines and wire saws are used, the former being preferred, except
for opening up and extending quarries. Several quarries, and at least
two marble-finishing mills, have been operated in Poland during recent
years. A variety from this country exported in considerable quantities
since 1930 is known as "Ropocevo" or "Blue-Jaune Caucasian."

Extensive deposits of coarse-grained white, pink, and green marbles
are quarried at Dunderland about 150 miles north of Trondhjem, Nor-
way. The rock is difficult to work and polish. "Swedish Green," from
near Norrkoping, Sweden, is best-adapted for floor tile and interior
decoration.

Africa. — Some of the most famous marbles of antiquity originated in
northern Africa and were used for statues, columns, tombstones, and
ornaments in Rome, southern Italy, and Carthage. The beautiful
so-called Numidian marbles were obtained chiefly in Algeria and Tunis.
Some quarries were on Mount Filfila on the Gulf of Numidia, and
several have been reopened since Algeria became a French province.
Available types include a pure white saccharoidal stone used for ancient
statuary, also ''Blue Turquin," a black variety, and a yellow arborescent
marble which has been identified as the original "Numidian" prized so
highly by the Romans.

Another celebrated locality is in western Algeria about 20 miles from
Oran, where a number of depressions are thought to be old Roman
quarries. The absence of debris around the openings may be explained
by its possible removal to preserve secrecy regarding quarry locations.
The following varieties are obtainable from the rediscovered quarries:
"Marmor Bianco," creamy white; "Rosa Carnagione," flesh; "Cipolin;"
and several yellow varieties. Beautiful breccias are obtained from a part
of the deposit, one of deep red which resembles, if it is not identical with,
the celebrated "Rosso Antico." Other reopened Roman quarries in the
commune of Arzeu, Province of Oran, revealed a red jasperUke marble,
"Rouge Etrusque"; a brownish red variety, "Marbre d' Ain-Ouinkel " ;
and several others.

Tunisian marbles were used extensively in Roman buildings, and their
source was discovered in the last century by a Belgian engineer at
Chemtou in the Medjerda River Valley. When the quarries were
reopened by a Belgian company an attractive violet breccia was obtained,
but the most highly prized discovery was the celebrated "Giallo Antico,"
which is identical with the stone of that name used abundantly in old
Rome. It is yellow, with a beautiful reddish tint, and takes a high polish.

Several quarries are operated in Morocco. Two gray marbles,
"Oued Yguem" and "Oqhnika," are obtained near Rabat; also a variety
named "Oued Akreuch," which dates back to the Roman period, as

FOREIGN BUILDING AND ORNAMENTAL STONES 331

indicated by samples found in the ruins of Chellah. Other Moroccan
varieties are "Beige Imperial," fawn-colored, and "Red of Fazi,"
quarried near Fez.

Other Foreign Marbles. — Marbles occur abundantly in many other
foreign countries, but most of them are either undeveloped, are used
locally, or are too distant to be of commercial interest. Few, if any,
reach the United States. Many beautiful varieties have been quarried
in Asia for Government buildings, temples, and palaces, such as the
famous Taj Mahal in India. Attractive marble is obtained in Victoria,
Australia. Some South and Central American countries report structural
and ornamental types. An undeveloped white statuary marble occurs
in the Province of Cordoba, Argentina. A highly decorative purple
material from the same province, which has been identified as fluorite, is
used for the manufacture of novelties. Marbles of many colors, from
various parts of Chile, notably in the Provinces of Aconcagua, Los Andes,
Antofagasta, Arica, and Magallanes, have been described, but production
is limited to a few hundred tons annually for local use. A large deposit
of high-grade statuary marble occurs on Cambridge Island, Magallanes.
Large deposits are reported at Santa Marta, Colombia; in the Province
of Azuary, Ecuador; and in Venezuela. Marble has been produced at
Zacapa, Guatemala.

On3rx Marble. — In its true mineralogical sense onyx is a banded form
of cryptocrystalline quartz related to agate and jasper. Onyx marble, or
Mexican onyx, is a form of calcium carbonate that received the name
because it also had a banded structure. This type of marble is deposited
from cold-water solutions of calcium carbonate, usually in caves; hence,
the name "cave onyx" is sometimes applied to it. Onyx marbles are
not uncommon, but large, sound blocks are rare.

The most famous deposits in the world occur within an area of
about 500 acres in Lower California, Mexico, at the small town of El
Marmol, 330 miles southeast of San Diego, Calif., by road, and 51 miles
inland from the Port of Santa Catarina. The largest are on a mesa
about 40 feet high, 3,000 feet long, and 1,200 feet wide. The workings
are known as the New Pedrara quarries. Commercial onyx occurs in
three beds. The uppermost is thin and highly colored, and provides
relatively small masses suitable for novelty work such as automobile
gear-shift balls, pen bases, lamp fittings, ash trays, book ends, and
candlesticks. The second bed is 1 to 2 feet thick and furnishes both
novelty and block onyx, and the third or lowest stratum supplies large
blocks 1 to 4 feet thick that may be cut into sound slabs for decorative
use in banks, theaters, hotel lobbies, and for soda fountains. Explosives
are used only in stripping; blocks are separated in the quarry by plug-
and-feather wedging. Normal annual production is about 25,000 cubic
feet, and a reserve of 1,500,000 cubic feet is said to be in sight.

332 THE STONE INDUSTRIES

The most difficult problem is transportation, for blocks must be
hauled in 5-ton trucks with trailers 51 miles to Santa Catarina, where
storage yards are maintained. Stiff-leg derricks on a 400-foot wharf
load the blocks on lighters which carry them to ships lying beyond the
breakers. From there they are conveyed to San Diego, where they are
manufactured into finished products or held in bonded yards for shipment
to many countries.

Mexican onyx is beautifully marked and takes an excellent polish.
It has a wide reputation and has been sold throughout the world since
1894. During 1929, 18,687 cubic feet in rough blocks, valued at $78,889,
were exported to the United States. Qorresponding figures for 1930
were 17,203 cubic feet, valued at $69,120; and in 1937, 13,253 cubic feet,
valued at $56,726.

Onyx marbles in France are confined to the slopes of the Pyrenees.
The most noteworthy is "Stalactite du Bedat" quarried in Hautes-
Pyr^nees and manufactured into ornamental objects at Bagneres-de-
Bigorre. Famous onyx marbles occur in the Province of Oran, Algeria.
There are two main varieties — dark and light. Some varieties are so
translucent that they have been used in Paris for lamp shades and for
church windows. Algerian onyx was quarried many centuries ago and
used for architectural decoration in mosques, temples, and other noble
structures. Highly decorative stalagmitic onyx occurring about 10 miles
from Constantine, the capital of the department of the same name in
Algeria, was quarried by the Romans and is marketed today.

Egyptian onyx, erroneously called "Egyptian alabaster" is one of
the most important of the ancient decorative stones. The Egyptians
used it from the time of the First Dynasty for sarcophagi, for interior
decoration in temples, and for vases and other objects. Many deposits
were worked in the Nile Valley of Upper Egypt, but most of them have
been worked out or abandoned for other reasons. Recent supplies are
obtained only near Assiut, the site of ancient Lycopolis.

Translucent onyx marbles, with attractive green, brown, and red
veinings, occur at several points in Argentina, principally in the Provinces
of San Rafael, Mendoza, and San Luis. They are used for making objects
of art, such as cameos and statues, and for architectural purposes, chiefly
for interior decoration of large public buildings. Exports range from 50
to several hundred tons annually and in 1924 reached a high figure of 585
tons. France, Belgium, Italy, and Germany were formerly the chief
destinations, but much of the onyx now reaches the United States (see
table page 317). It is sometimes erroneously called "Brazihan onyx."
Onyx production has been reported from the Province of Atacama,
Chile.

In Hanover, Germany, an onyxlike mineral locally named "onysette"
is being worked in a small way to produce blocks which are manufactured

FOREIGN BUILDING AND ORNAMENTAL STONES 333

in both Germany and Holland into office ornaments, clocks, cigar boxes,
and otlier novelties. At first the deposit was quarried by blasting, which
caused excessive waste, but more recently cutting and wedging methods
have been used, and larger, sounder blocks are produced.

FOREIGN SLATES

Slates from foreign countries have never attained a strong foothold
in American markets, as values of total imports range only from $50,000
to $100,000 annually. Nevertheless, long-established, important slate
industries in several European countries are potential, if not actual,
competitors.

Canada. — Slate deposits of commercial importance in Canada are
confined to the eastern part of Quebec. Black slates suitable for roofing
material are best-known in the counties of Richmond, Missisquoi, and
Temiscouata, but the roofing-slate industry has stagnated during recent
years. The quarry that has produced most consistently was opened
in 1868 at New Rockland, Richmond County, where the slate occurs in a
belt about 200 feet wide dipping 70 to 80° and with vertical cleavage.
Quartz veins are present in places. Recently a deposit of green slate
has been worked on the same property. Black slates have been produced
at times near Corris and Asbestos. In 1922 a black-slate quarry was
opened at Mystic about 50 miles southeast of Montreal.

In 1908 a large deposit of black slate was uncovered during railway
construction near Glendyne in Temiscouata County about 120 miles from
the city of Quebec. Slaty cleavage and bedding dip about 24°, and
quarry conditions are favorable. Substantial production was maintained
until 1915 when the plant was destroyed by fire, and there has been no
subsequent activity. Red and green slates have been found in several
places; utilization for roofing purposes has been negligible, but two plants
are in operation for the manufacture of granules.

Wales. — The slate industry of Wales stands in the forefront among all
slate-producing industries of the world; it has the largest excavations,
employs the most men, and produces the greatest tonnage of finished
products. There is evidence that the Welsh deposits were worked as
far back as the Roman occupation; but as an important industry, slate
production dates from the closing years of the eighteenth century.
In 1925 North*^ stated that about 60 slate mines and quarries were in
active operation.

In Wales slate occurs in five important areas:

1. In Carnarvon, in beds of Cambrian age; this area comprises
the important districts of Bethesda, Llanberis, and Nantlle, of which the
two most famous quarries are the Penrhyn and the Dinorwic. The
Bethesda slates are shipped from Port Penrhyn, Bangor; those of Llan-

« North, F. J., The Slates of Wales. Univ. of Wales, Cardiff, Wales, 1925, p. 50.

334 THE STONE INDUSTRIES

beris from Port Dinorwic; and the NantUe slates from Carnarvon, The
slates are reddish purple, blue, or green and lie in a formation 500 to
1,000 feet thick.

2. At Blaenau Festiniog in Merioneth, in rock of Ordovician age,
where the slates are blue or gray, have a lustrous surface, and are finer-
grained than those of the first area. They are obtained from underground
mines, the best-known of which are Croesor, Llechwedd, Maen Ofiferen,
Manod, Oakeley, Votty, and Bowydd. Portmadoc is the point of ship-
ment for this region.

3. Between Towyn and Corris, where slates of both Ordovician and
Silurian age are available; this district includes a series of fine-grained
homogeneous slate rocks about 1,500 feet thick. Two important beds,
known as the Broad Vein and the Narrow Vein, are quarried wherever
the cleavage is sufficiently well-developed. The products are shipped
from the ports of Towyn and Machynlleth,

4. In the country between Llangollen and Corwen, where slates
are quarried or mined principally at Moel Ferna, Glynceiriog, and other
points near Corwen,

5. Slate of Ordovician age in the Prescelly district of Pembroke and
adjacent parts of Carmarthen. That from the Glogue quarries is bluish
gray, while near Prescelly (Maenclochog, Llandilo, and Gilfach quarries)
it ranges from olive green to silvery gray.

The two most important producing districts are Blaenau Festiniog
in Merioneth, where production is from underground mines and the
Bethesda-Llanberis area in Carnarvon where it is mined from open
quarries.

The largest mines at Festiniog are the Oakeley, Greaves, Votty, and
Maen Offeren, which together have about 130 miles of tramway tracks.
There are five beds of commercial slate ranging from 26 to 126 feet in
width and dipping 30 to 45° into the mountain. They are known locally
as the New Vein, Old Vein, Small Vein, Back Vein, and North Vein,
Slaty cleavage dips at a steeper angle than the beds and therefore crosses
them diagonally. A bed of chert 5 to 10 feet thick over the New
Vein forms a good roof. An inclined shaft is sunk just beneath it, from
which levels are driven along the strike and also north and south to
open up other veins. From these drifts good slate is removed; chambers
30 to 45 feet wide and 40 to 50 feet high are thus formed, pillars of equal
width being left between them for roof support. Chambers are worked
out at deeper and deeper levels, the depth between floors ranging from
50 to 70 feet. In one mine the depth of the workings from the highest
to the lowest floor is over 1,400 feet, A few years ago it was reported
that the quarry had 50 miles of railroads, 4 miles of pump mains, and
12 miles of compressed-air mains. Slate had been removed from 26
levels, work being carried on at different levels simultaneously. The

FOREIGN BUILDING AND ORNAMENTAL STONES 335

chambers are among the largest and most numerous in any underground
operation in the world. The mines are electrified and well-equipped.
Slate blocks, roughly trimmed in the pits, are hauled up an inclined
shaft by cableway in wagons of about 2)4 tons capacity and conveyed
to sawing and dressing sheds. The problem of waste is serious, the
proportion being 10 to as high as 30 tons for 1 ton of good slate.

The Penrhyn and Dinorwic quarries are good examples of the open-
pit terraced type ; in fact, they are among the largest quarry workings in
the world. Before 1793 the site now covered by the Penrhyn quarries
was worked by numerous independent men, each paying an annual
rental of £1 or £2, but in that year Richard Pennant obtained pos-
session and worked the district as a unit. The force of 150 men was
increased to 600 in 1808 and to 3,000 in 1880. Through these many
years of activity a remarkable series of steplike ledges or terraces each
about 70 feet high, has been developed; the topmost stands at a height
of about 1,800 feet on the shoulder of the mountain. At a distance they
resemble the great open-pit iron mines of Minnesota, except that they
extend up the mountain sides rather than sink in great depressions.
Work proceeds simultaneously on each terrace. Slate blocks are sep-
arated by drilling and wedging or by light charges of powder. Neither
channeling machines nor wire saws have been used successfully in Welsh
quarries or mines. Rough blocks are trimmed on the terrace floor and
removed laterally by tram cars. Other open quarries are in the form of
great pits 300 to 500 feet deep, some of which are also terraced.

Roofing slate is the chief product of Welsh quarries. Splitting is
done by hand and trimming usually by power-driven rotary trimmers
similar to those used in Vermont. Originally all slates were of one size,
about 11 X 5}^ inches, but about 1735 a second size called "doubles,"
approximately 13 X 7 inches, was produced. Later other sizes were
introduced and given the fanciful names "ladies," "countesses," "duch-
esses," "princesses," and "empresses." The last mentioned were the
largest, measuring about 26 by 16 inches. Slates are now made in a
great many sizes comparable with those established in the United States,
and, as in America, different markets have different requirements as to
size. Roofing slate is sold by the mille (1200 pieces) rather than by the
square. Welsh slate is used to a limited extent for flagging, billiard
tables, cisterns, dairy and laboratory tables, electrical switchboards, and
school or "writing" slates, as they are called in Wales.

Welsh slate has an extremely low porosity and is remarkably resist-
ant to acids and weathering agencies. It has won worldwide reputation
for service and before the World War had very extensive foreign markets.
The industry was practically paralyzed during the war but has recovered
to some extent. In 1931, 27 active companies were listed. Very little
Welsh slate reaches American markets.

336 THE STONE INDUSTRIES

England. — Slate has been quarried for many centuries in England
from the upper Devonian rocks of Cornwall, and years ago it had an
extensive continental trade. Quarries are numerous in this district, but
the Delabole in St. Feath and the Lamb's House at Tintagel are the only
large ones recently operated. The slate is blue-gray, lighter in weight
than Welsh slate and very durable. A limited quantity of rustic red is
available. Well-equipped mills for the manufacture of structural prod-
ucts are operated at Delabole. Devonian and Carboniferous slates
have been worked in a small way in Devon. Some weather to dull
brown and are used where a rustic effect is desired.

Slates from the Silurian and Devonian rocks of the English Lake
district split less easily and in thicker slabs than Welsh material and
therefore produce fewer slates per ton of rock, but the product is very
durable. Green slates are obtained at Keswick, Cumberland. The roof
of Cockermouth Castle, covered with Cumberland slate about 1750, is
said to be in excellent condition. The Caudale roofing slate quarries of
Westmorland operated more than 100 years ago but idle since 1914, were
reopened in 1933. Underground methods are employed. High-quality
gray-blue roofing material is quarried near Kirkby-in-Furness, northern
Lancashire.

Slate of Cambrian age is quarried at Sulby near Ramsey on the Isle of
Man.

Ireland. — Greenish Devonian slates from Valentia Island, County
Kerry, are well-suited for flagging and were shipped to England before
the Welsh flagging industry was developed. Quarries in Tipperary
County opened as early as 1826 were worked extensively, and about 700
men and boys were employed in 1845. Although the industry has
declined to some extent, it is still active and in 1927 employed 120 men.
Quarries and mills are well-equipped; slabs are cut to length with
diamond saws. The slate rock, of lower Silurian age, is hard and blue-
gray. About 75 per cent of the production, chiefly roofing slate, is sold
in Ireland and 25 per cent in Scotland. Other districts where slate is
or has been produced include Ross Carberry and Bantry, Cork
County; Shillelagh, Wicklow County; and several places in Wexford,
Waterford, and Clare Counties. Local slates have been used quite
extensively for roofing and to some extent as building stone in southern
Ireland.

Scotland. — In Scotland slate is quarried in Argyll, Perth, and Dum-
barton Counties from rocks of Ordovician age. The most important
quarries are in the black-slate belt on the west coast of Argyll.
Quarries at Easdale, an island in the Firth of Lome, have been operated
more than 200 years. Numerous crystals of iron pyrite are present, but
they are unusually resistant to weathering, retaining their original
luster on roofs that have been exposed for more than a hundred years.

FOREIGN BUILDING AND ORNAMENTAL STONES 337

Renewed activity in the ancient slate quarries at Ballachulish on the
mainland in northern Argyll was in prospect early in 1933.

France. — An important slate industry has existed in France for many
years. The larger quarries are situated in six widely separated districts :

1. Angers, western France, where numerous large workings are to be
found. There are four principal slate veins of Ordovician age, designated
the "northern," "southern," "intermediate," and "extreme southern."
They stand at angles at 60° to the vertical and extend to great depth.
They are mined separately because the veins have barren rock between
them. At Angers slate is mined underground through vertical shafts,
and an ingenious method of overhead stoping is employed. A shaft is
sunk to considerable depth, possibly 800 feet, lateral drifts are projected,
and slate is broken down from the roof. Good slate is hoisted out, and
waste remains on the floor, which is gradually built up to keep pace with
upward extension of the roof. This method, designated "Blavier," was
first introduced in 1877, and it is claimed that two thirds of the entire
production of France is mined in this way or in some modification of it.
The same method was introduced later at Monson, Me, Farther west
in the same belt the rock is greatly jointed, and open-pit work is followed.
Angers slate of best quality is a strong, tough, blue-gray product, about
98 per cent of which is used for roofing, mostly in small sizes. The
quarries and mines are well-equipped with the most modern machinery.
Wire saws are used extensively.

2. Finisterre in the extreme northwest, at the western outpost of the
same series of metamorphic rocks that occur at Angers. Several large
quarries are situated conveniently for export trade.

3. Ardennes in the northeast. Highly metamorphosed slates of this
district are of Cambrian or pre-Cambrian age and more variable in
structure and color than in most areas. Fumay furnishes a micaceous
chloritic slate containing siderite crystals. At Revin south of Fumay it
is black, "Veine des Peureux." Slates at Deville are green, gray-green,
and blue and contain magnetite. At Saint Anne they are blue, red, green,
and violet, extremely fissile, and very durable. Workings throughout the
district are chiefly deep underground mines, the products of which have
easy access to Belgium and Holland by way of the Meuse River and to
many points in France by canal and railway. About 85 per cent of the
product is used for roofing, and most of the remainder for electrical panels
and switchboards.

4. Correze, in central France, where a small output of slate is
quarried.

5. The Pyrenees, in the extreme south, where slates occur in many
localities. The principal quarries are near Bagneres-de-Bigorre and
Lourdes. Transportation conditions are less favorable than in the
districts previously described. Details of the method of using wire

338 THE STONE INDUSTRIES

saws in underground chambers at Labassere, Hautes Pyrenees, have been
described by Delcourt.^^

6. Savoie, in the southeast near the ItaHan frontier. Here slates
occur in rocks of various geologic ages ranging from the old crystallines to
Carboniferous. They contain more lime and alumina than most slates
and tend to whiten with age. The numerous quarries of the district fall
into four main groups : (a) Saint Jean de Maurienne and Saint Colomban-
des-Villards, which is the southernmost and chief operation ; (6) the center
district; (c) the northern Flumet quarries; and (d) Upper Savoie, including
Morzine, Montriond, and Houches quarries. Slates of best quality are
obtained from the center district.

The Angers and Ardennes beds are the most important, together
yielding about 70 per cent of the total production of the country. French
slates are used primarily for roofing, and on an average less than 1 per
cent is employed in slab form. Before the World War France had a
large export trade to other European countries and to South America.
Since that time exports have decreased very greatly owing to require-
ments of the reconstruction areas. A small but increasing amount
reaches the United States.

Belgium. — The Belgian slate industry is centered at Neuf chateau and
near Martelange in the Province of Luxemburg. In the latter region
beds dip about 55° and are worked underground. The side walls of
chambers are cut with wire saws. Recovery of good slate is said to be
as high as 25 per cent of gross production. Products of the mines, some
of which have been in operation since 1784, are used chiefly for roofing,
with minor quantities for billiard tables and other slab work; a highly
siliceous variety is used for whetstones. The industry was paralyzed
during the World War but has recovered to some extent. Recovery
approaching former activity is doubtful because of the increasing diffi-
culty of working in deep mines and the threatened exhaustion of available
supplies.

Luxemburg. — ^Two large mines are in operation near Martelange, a
town on the border between the Province of Luxemburg, Belgium, and
the Grand Duchy of Luxemburg, a position which accounts for reference
to the town under both countries. The slate is in nearly vertical beds,
curving back and forth at steep angles which necessitate working in
underground mines, now about 300 feet deep. The chief product is
roofing slate, with a minor output of structural slabs. Between 300 and
400 men are employed, and annual production averages about 10,000,000
slates, ranging in size from 6 by 9 to 14 by 20 inches.

Portugal. — A slate deposit about 4 miles long and ^i mile wide is
situated at Vallong about 11 miles northeast of Oporto. It is worked to a

*^ Delcourt, E., A Scientific Method of Quarrying Slate. Quarry and Surveyors'
and Contractors' Jour., vol. 27, no. 300, 1922, pp. 52-56.

FOREIGN BUILDING AND ORNAMENTAL STONES 339

depth of about 100 meters; quality deteriorates below this point. Beds
stand at angles of 80 to 85°. The slate, which is dark blue-gray, is
graded as jfirst and second quality. When free from iron pyrite it is
said to be an excellent electrical slate, but much of it contains this
mineral and therefore can be used only where a low-voltage current is
employed. Products manufactured include roofing slate, bricks, slabs,
electrical panels, billiard-table tops, school slates, and pencils. From
85 to 90 per cent of the production is exported, increasing quantities
reaching the American market.

Spain. — Slate is produced chiefly in the Provinces of Badajoz and
Guipuzcoa, with minor production in Coruna, Guadalajara, Lugo, and
Zamora. In 1929 the industry employed 156 men and produced slate
valued at 682,957 pesetas.

Italy. — From 85 to 95 per cent of all Italian slate is obtained in the
Province of Genova, and the largest quarries are near Cicagna. This
slate is used for roofing, blackboards, billiard tables, and electrical panels.
Export trade in slate to other European countries has declined greatly
during recent years in all branches except billiard tables. Italy is the
most important foreign source of supply of slate entering the United
States, and imports during recent years have ranged in value from $17,000
to $43,000. The unit. value of Italian slate sold in America is higher than
that of similar products shipped elsewhere; this may be due partly to the
shipment of higher-grade products and partly to trade in semimanu-
factured rather than in crude blocks. Practically no roofing slate is
shipped to America, as it would not endure in the climate. It is claimed
that Genova roofing slate will deteriorate in two years in England.
Some Italian blackboard slate reaching the United States has been
found on analysis to contain about 40 per cent calcium carbonate.

Germany. — Slate is mined principally in the Hunsruck and Eifel
regions, on the Moselle, on the Rhine, in Westphalia, and in Saxony.
As much of it occurs in beds with a steep dip and nearly vertical cleavage,
underground operation is necessary. An overhead-stoping method
similar to that used at Angers, France, has been introduced. German
slate is used for roofing, for floors, steps, and other structural purposes,
for billiard tables, electrical panels and switchboards, and for school
slates. Very small quantities reach America.

Switzerland. — Commercial slate quarries are operated in the Cantons
of Bern, Glarus, Saint-Gall, and Valais, the principal quarries being in the
last two named. Both underground and open-pit mining methods are
used. Since tile is replacing slate as a roofing material in Switzerland,
slate has been diverted to some extent to slab uses, such as billiard tables,
school slates, sanitary applications, and flagging.

Norway. — Thick, heavy, architectural slates, which are relatively
coarse-grained and resemble mica schists are quarried by one large

340 THE STONE INDUSTRIES

company near Bergen, Small knots of silica give the appearance of
bird's-eye maple, and the surfaces show many attractive colors. The
stone is well-adapted for ornamental flagging or for heavy roofs of large
structures.

Sweden. — The best slate of Sweden, comparable in quality with that
from Wales, is quarried at Kellsvik near Lake Wena. Thick, heavy slates
are obtained in several other localities.

Australia. — Slate deposits have been developed near Tenterden,
Western Australia, but even the stimulus of a Government bonus has
failed to promote extensive production.

India. — Several thousand tons of slate are produced annually in
India. Production is centered in the Kangra district of the outer
Himalayas; near Rewari in the Gurgaon district south of Delhi; and in
the Kharakhpur Hills, Monghyr district, Bihar. The slate is used for
roofing and flagging, for small dishes and curry platters for native use,
and, with enameled surfaces, for electrical purposes. According to
report, a school-slate industry was established a few years ago in the last
district, with a monthly production of 22,000 framed slates.

Union of South Africa. — The only important slate operation in South
Africa is near Zwartruggens, Transvaal, about 100 miles northwest of
Johannesburg where, according to reports received by the writer in 1928,
a flourishing industry has been established. Marketed products include
blackboards, and roofing, structural, and electrical slate.

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1914, 264 pp.; vol. 3, no. 279, 1914, 304 pp.; vol. 4, no. 388, 1916, 333 pp.; vol.
5, no. 452, 1917, 236 pp.

Parnisari, Carlo. Mining Marble with Helicoidal Wire in Italj'. Eng. and Min.
World, vol. 1, no. 3, 1930, pp. 121-123.

Quarry Managers' Journal (monthly magazine devoted to the stone-quarrying indus-
tries). Institute of Quarrying, London.

Renwick, W. G. Marble and Marble Working. Crosby Lockwood and Son, London,
1909, 226 pp.

Slate Trade Gazette (monthly magazine devoted to the slate industry). Wilberforce
Press, Hull, England.

Stone (monthly magazine devoted to the building and monumental industries). Stone
Publishing Co., New York.

Swiss Cippolino Marble. Vol. 50, 1929, p. 685.

The Marbles of Spain. Vol. 50, 1929, pp. 504-505; 570-571.

Wagner, Percy A. Ornamental Building Stones of the Transvaal. South Africa
Jour. Ind., vol. 7, no. 8, 1924, pp. 523-529.

Wallace, R. C. and Greer, L. The Nonmetallic Mineral Resources of Manitoba.
Indust. Devel. Board of Manitoba, Winnipeg, 1927, pp. 9-20.

Warnes, a. R. Building Stones, Their Properties, Decay, and Preservation.
Ernest Benn, Ltd., London, 1926, 269 pp.

Watson, John. British and Foreign Marbles and Other Ornamental Stone. Cam-
bridge Univ. Press, 1916, 485 pp.

Williams-Ellis, M. L The Quarrying and Mining of British Slates. Quarry
Managers' Jour., vol. 13, no. 6, 1930, pp. 50-51; no. 7, pp. 95-98.

Wyberg, W. The Building Stones of the Union of South Africa. Union of South
Africa Dept. Mines and Industries, Geol. Survey Memoir 29, 1932, p. 244.

CHAPTER XIV

MISCELLANEOUS ROCKS AND MINERALS USED FOR BUILDING
AND ORNAMENTAL PURPOSES

Quite a variety of minerals and rocks not included in any preceding
classifications is used for structural purposes or for decorative effects.
Most of them are employed in small amounts but are interesting because
of their special adaptations or striking ornamental qualities. Those
briefly described include the more important minor materials used
for building purposes, interior decoration, furniture, or novelties,
but precious and semiprecious stones fall outside the scope of this
book.

Agalmatolite. — The name agalmatolite is given both to massive talc
and massive pyrophyllite (a hydrous silicate of aluminum and potassium)
but more properly is applied to the latter. There is evidence also that
some of the material designated agalmatolite, which was used for ancient
carving, consists of pinite, also a hydrous silicate of aluminum and
potassium closely related to muscovite, possibly a massive form of that
mineral. Agalmatolite, also termed "lardstone," "figure stone," and
"pencil stone," is soft and waxy and is used for carving, chiefly by the
Chinese, into ornamental dishes, miniature pagodas, and grotesque
images. It occurs in Saxony and China.

Large quantities of pyrophyllite occurring near Hemp, N. C, are
pulverized and used in the same way as talc. While some was used in
massive form many years ago for gravestones, chimneys, fireplaces, and
stove linings, apparently none of it possesses adaptability for carving
comparable with the Chinese product.

Alabaster. — Alabaster is a massive, fine-textured form of gypsum,
which has the composition CaS042H20 — a hydrous calcium sulphate.
Gypsum is a very common mineral, and large quantities are calcined to
make plaster of paris, which is widely used as finishing plaster and for
many other products. A very small amount is employed in massive
form. It is usually white; and, as its hardness is only 2 in Moh's scale,
it may be cut and carved easily with knife or saw.

Pink to white alabaster of good quality has recently been quarried
near Fort Collins, Larimer County, Colorado, and manufactured into
lamps, urns, vases, bowls, jars, pen stands, book ends, and other novelties.
There has been little or no production of alabaster elsewhere in the United
States although it is reported in several localities.

342

MISCELLANEOUS ROCKS AND MINERALS 343

The alabaster industry has been developed most fully in Italy, where
high-quality material occurs in several localities, chiefly in Tuscany and
Piedmont. Clouded and veined varieties are obtained near Volterra,
and pure white alabaster principally near Castellina. Here it was used
in ancient times for making carved sarcophagi in which the ashes of the
deceased were buried in the mountain sides. The deposits have been
worked for more than 2,000 years. The alabaster occurs in smooth,
ovoid masses up to 3 or 4 feet in diameter irregularly disseminated in beds
of marl or clay. In recent years wire saws have been used for cutting
out blocks to avoid the fracturing caused by blasting. Alabaster working
for the production of miscellaneous articles was until the last decade a
hand-carving process conducted by small groups of artisans residing in
Volterra, Florence, and Pisa. Keen competition was encountered with
French and German workers, who employed machinery to take the place
of hand carving ; and in consequence, lathes, sawing machines, and other
types of mechanical equipment were introduced in Italy about 1920. A
modern factory consuming about 5,000 tons of alabaster a year was
erected at Leghorn in 1927. The products of this factory include
statuettes, lamp shades, pedestals, vases, and various novelties. Lamp
shades and some other products are artificially colored.

Statuettes, vases, and novelties carved in semitransparent alabaster
are hardened and rendered opaque by being placed in cold water, which is
slowly raised to the boiling point and allowed to cool. Thus, they are
made to resemble Carrara marble and often are sold as such. Recent
production in Italy has been entirely from the Volterra-Florence region.
Manufactured alabaster valued at about $50,000 is exported to the
United States annually.

Good-quality alabaster occurs in gypsum deposits near Paris, France,
but is used much less extensively than in Italy. Beautiful white alabaster
is reported from the Provinces of Guadelajara and Saragossa, Spain. In
England alabaster was quarried many years ago at Chellaston, Derbyshire,
and at Hanbury, Staffordshire. Alabaster said to have been obtained in
Devonshire was used for bank counters in New York many years ago.
Alabaster is also obtained in Rumania and Egypt.

Amazonite. — Amazonite, or Amazon stone, is a green variety of
microcline, a potash feldspar. Deposits are reported in the Ural Moun-
tains of Russia; near Antsirabe in Madagascar; on the east coast of James
Bay, Canada; and at Florissant near Pike's Peak, Col. It is produced
commercially for cutting and carving and for concrete facing at Chula
and Amelia Court House, Va.

Catlinite. — Catlinite, also called "Indian pipestone" because it was
used by the Sioux Indians for carving pipes and other articles, is a form of
indurated clay of variable composition. It is dull red, sometimes flecked
with yellowish dots. The most notable deposit is near the town of Pipe-

344 THE STONE INDUSTRIES

stone, Pipestone County, in southwestern Minnesota, where it occurs in a
bed about 18 inches thick interstratified with Sioux quartzite. Tomahawks
and other novelties carved from it are sold at Pipestone. Indians fre-
quently visit the deposit to obtain stone for use in their ceremonies.

Clay. — Houses with clay-rammed walls have been constructed both in
Europe and in America. According to report, they have endured in
England for over 100 years. Sod huts and adobe dwellings are among the
earliest types of human habitations.

Diatomite, Tripoli, and Pumice. — Both diatomite and tripoli are used
chiefly in pulverized form; however, massive diatomite, particularly that
occurring at Lompoc, Calif., is sawed into bricks or blocks for furnace
lining and to a small extent for light-weight building material. It has
been used as a building stone in southern California. Massive forms of
both diatomite and tripoli are shaped into filter blocks. In Japan
block pumice is used for the construction of earthquake-proof houses.

Fluorite. — Small fragments of the mineral fluorite (CaF2) are used in
large quantities as a flux in steel furnaces, and in granular or pulverized
form it is employed in many other ways. Perfect transparent crystals
are used in certain optical instruments. Fluorite as a structural or
ornamental material is unusual, but a notable example of such use in the
Province of Cordoba, Argentina, has been recorded. Here it may be
obtained in blocks sufficiently large and sound to be cut into slabs for
panel work, or to be used for columns or bases, and its color combinations
of purple, green, and amber with varying shades in transmitted and
reflected light make it a beautiful stone for such decorative uses. Most
of it, however, is carved into novelties and jewelry. Because of its
resemblance to lapis-lazuli it has been named "litoslazuli." A variety
known as "blue John," obtained in Derbyshire, England, is made into
novelties and ornaments. The Indians used fluorspar obtained near
Rosiclare, 111., for carving ornaments.

Jade. — Material known as jade includes two minerals, nephrite and
jadeite, the former being the more common. Nephrite is a monoclinic
amphibole having a composition expressed by the formula Ca(MgFe)3
(8103)4. It has a hardness of Gf^ and is therefore nearly as hard as
quartz. Colors range from white to leaf green and dark green, the green
shades being due to the presence of ferrous iron. Jade knives and other
implements have been found in prehistoric ruins, such as the Swiss lake
dwellings. The Chinese are masters in working this very hard and
tough mineral, and their delicate, intricate carvings are highly prized
among collectors. MerrilP refers to a white jade object in the Indian
museum, London, which required three generations of workers 85 years
to complete. The great seal of China is carved from jade. The mineral

" Merrill, G. P., Stones for Building and Decoration. 3d ed., John Wiley & Sons,
Inc., New York, 1910, p. 349.

MISCELLANEOUS ROCKS AND MINERALS 345

occurs in China, Turkistan, Siberia, New Zealand, Alaska, and British
Columbia, Canada. Jadeite, a monoclinic pyroxene, resembles nephrite
very closely and is used in the same way. The most important locality
for jadeite is the Mogaung district of Upper Burma.

Labradorite. — An iridescent variety of plagioclase feldspar has been
named "Labradorite" because of its occurrence at Paul's Island on the
coast of Labrador. Undeveloped occurrences have been noted in the
Province of Quebec, Canada. A rock containing an abundance of this
type of feldspar occurring near Laurvik, Norway, has been named
"Laurvikite," and is used widely as an ornamental syenite. It has been
described previously under the granites of Norway.

Lapis-lazuli. — Lapis-lazuli is not regarded as a homogeneous mineral,
but rather as an intimate mixture of several minerals; the chief of these,
lazurite, gives it a rich blue color. On account of this color lapis-lazuli
is much in demand for ornamental inlaid work, but as it is costly it is
usually employed only as a thin veneer. Large vases of lapis-lazuli are
on display in the Vatican Museum, Rome. Commercial supplies are
obtained in Afghanistan, Siberia, and China, and samples have been
obtained in San Bernardino County, California. It was mined in the
Province of Antofagasta, Chile, from 1852 to 1896 when operation ceased.
A deposit of several thousand tons of high-grade material has been
reported in the Province of Coquimbo, Chile.

Malachite and Azurite. — Malachite is a green hydrous carbonate of
copper, CuC03Cu(OH)2, occurring above ground-water level as an altera-
tion product of copper-bearing sulphide ores, occasionally in masses large
and compact enough to be used for ornamental purposes. Small pieces
are used for vases and ornaments, while the larger masses are sawed into
slabs for table tops, panels, bank counters, and similar products. The
most noted source of malachite is Nijni Tagilsk in the Russian Urals,
where like cave onyx it occurs as stalagmites with beautiful bandings
in various shades of green. Solid blocks 3 feet thick have been obtained.
Two malachite altars in the church of Saint Paul Outside the Walls,
Rome, were a gift of one of the Russian czars. Large masses have been
found also in the Burra Burra Mine near Adelaide, Australia, and in the
copper mines of Arizona.

Azurite is a blue hydrous copper carbonate having the composition
2CuC03.Cu(OH)2. It occurs in large masses less commonly than
malachite but may be interbanded with it, forming a very striking and
beautiful combination of concentric green and blue bands.

Meerschaum. — Meerschaum, or sepiolite, is a hydrous magnesium
silicate occurring in compact, granular, nodular, or earthy form, usually
as an alteration product of magnesite or serpentine. When pure and dry
it is light enough to float on water. The best-known deposits from which
most of the commercial material originates are in Anatolia, Asia Minor,

346 THE STONE INDUSTRIES

about 120 miles southeast of Istanboul (Constantinople). Deposits have
been reported in the Islands of Euboea and Samos, Greece; near Hrub-
schitz, Czechoslovakia; in Bosnia; in Morocco; and near Vallecas,
Madrid, and Toledo, Spain. It occurs in the United States in Grant
County, N. M.; Chester and Delaware Counties, Pa.; Westchester
County, N. Y.; Duchesne County, Utah; and at the Cheever Iron Mine,
Richmond, Mass. American deposits have little, if any, commercial
importance. The principal use is for carving into smoking pipes and cigar
or cigarette holders. Since 1767 the greater part of the carving industry
has been centered at Ruhla in the Thiiringian Forest, Germany.

Mica Schist. — Fine-grained mica schists quarried in Grafton County,
N. H., are used for the manufacture of whetstones and other abrasives.
Garnet, rutile, and quartz crystals provide the cutting surfaces. Similar
rock is quarried from adjoining deposits in Orleans County, Vt.

Porphyry. — Porphyry is a volcanic rock consisting of crystallized
minerals scattered throughout a fine-grained groundmass. A notable
decorative rock of this type is the red porphyry of upper Egypt, described
by Pliny. White and light pink feldspar crystals are set in a groundmass
which owes its dark red color to the presence of piedmontite. It occurs
in a dike 80 to 90 feet thick and is obtainable in large blocks. It was
widely used by the Romans for columns, baths, sarcophagi, and statuary.
Difficulties of transportation have discouraged recent development.

Green porphyry from the Province of Laconia, Greece, also was used
by the ancients. It consists of a dark, olive green groundmass sprinkled
with light green feldspar crystals and small bluish agates. It has rarely
been used in modern decorative work.

Quartz. — Various ornamental forms of quartz, such as agate, onyx,
jasper, and heliotrope, are to be regarded as semiprecious stones rather
than structural materials. Fossil wood, also called petrified or agatized
wood, sometimes occurs in large masses that are cut into slabs and
polished for very beautiful table tops, panels, and novelties. It is very
expensive to work on account of its hardness. Apache County, Ariz., is
the district most noteworthy for fossil wood.

Flint is another form that has uses other than as a semiprecious
stone. It was one of the earliest minerals worked by man for the manu-
facture of arrowheads, skinning knives, and implements of war.

Snow and Ice. — The mineral substance water (H2O), which solidifies
as snow or ice at temperatures below 0°C., finds some use as a structural
material. Such use is confined chiefly to areas between the Mackenzie
River in Canada and the Atlantic Ocean (except in parts of Labrador)
where the Eskimos dwell in igloos or dome-shaped snow houses. An
important feature of Canadian winter sports is an ice carnival, for which
it is customary to build a palace entirely of blocks of ice. Log cabins
in the Far North are sometimes coated with ice to make them weather-

MISCELLANEOUS ROCKS AND MINERALS 347

proof. When the winter season has advanced to a point when freezing
weather is practically continuous water is thrown over the cabin walls
and allowed to freeze. A coating of any desired thickness may be
obtained by repeated application of water.

Sodalite. — Sodalite is a silicate of sodium and aluminum containing
chlorine. A beautiful blue variety occurs in the northern part of Hast-
ings County, Ontario, Canada. It is claimed that sodalite-dotted rock
may be obtained in blocks 4 feet square and almost pure sodalite in
smaller pieces, A shipment of 130 tons was sent to England in 1906
and used as decorative material in a London residence. The high pro-
portion of waste and the difficulty of working the rock have discouraged
further development. Occurrences of the mineral in small masses are
reported from Ice River, British Columbia, Canada; the Ural Mountains;
Mount Vesuvius; Norway; and Litchfield, Me.

Bibliography

Merhill, G. p. Stones for Building and Decoration. 3d ed., John Wiley & Sons,
Inc., New York, 1910, 551 pp.

Kraus, E. H. and Holden, E. F. Gems and Gem Materials. McGraw-Hill Book
Company, Inc., New York, 1925, 222 pp.

Ladoo, R. B. Nonmetallic Minerals. McGraw-Hill Book Company, Inc., New
York, 1925, 686 pp.

Watson, John. British and Foreign Marbles and Other Ornamental Stones. Cam-
bridge University Press, 1916, 485 pp.

CHAPTER XV

DETERIORATION, PRESERVATION, AND CLEANING OF

STONEWORK

DETERIORATION OF STONE

Effects of Time on Stone. — Nothing in nature is immune from change.
Outcrops of rock bearing unmistakable glacial striations showing that
they have been exposed for countless years may present little evidence
of decay, but careful examination will undoubtedly reveal the beginnings
of alteration. Some rocks decay with comparative rapidity. There-
fore, endurance is a very important quality of building stone, particularly
in regions where weather conditions are severe.

The use of stone as a structural material in America is comparatively
so recent that architects, builders, and engineers have not been faced
generally with serious problems of deterioration. Few of our oldest
structures are more than 200 years old, and most of them have stood
for less than a century. In the Old World many stone structures date
back at least 1,000 years and in the even climate of Egypt several thou-
sand years more, but gradual physical or chemical changes have led in
some instances to a degree of deterioration that demands attention. In
England decay of building stones has become a matter of such concern
that in 1923 a Government committee known as the Stone Preservation
Committee was formed to investigate fully the subject of their deteriora-
tion and preservation.

Because of the kaleidoscopic changes of modern civilization many
buildings in America are designed to stand for periods not exceeding a
quarter of a century. However, monumental structures, cathedrals,
shrines, and public buildings of many sorts should be built for future ages
as well as for the present. Fortunately, architects of our greatest
structures are exercising commendable foresight and are using only
those materials and designs that will endure for centuries. The Wash-
ington Cathedral, for example, is being built to stand with little need of
repair for many hundreds of years. It is significant that the architects
use very little metal, except in roof supports, which are easily replaceable;
foundations, walls, and towers are of solid masonry embedded on native
rock.

Agencies That Cause Change. — Disintegration of rock involves com-
plex processes, some of which are not well-understood; but its importance
to the stone industries is so great that a brief discussion of the principles

348

PRESERVATION AND CLEANING OF STONE 349

governing decay is justified. More detailed data are presented by
Warnes and Schaffer (see bibliography at the end of this chapter).

Agencies that bring about deterioration in rocks are both chemical
and physical. They may be of external origin entirely, or their effects
may be intensified by reactions within the rock itself. The chief causes
of deterioration may be classed as follows:
Reactions chiefly chemical

Solution

Alteration and replacement of minerals
Changes or agencies chiefly physical

Expansion and contraction

Frost action

Abrasion

Settlements
Causes both chemical and physical

Plant growth

Marine borers

Faults in accessory materials and workmanship
The foregoing causes of deterioration are considered in order in following
paragraphs.

Reactions Chiefly Chemical. Solution. — The solubility in pure water
of practically all building stones is very slight. Rain water, however, is
rarely pure, for it dissolves gases from the air through which it falls, and
also various compounds that are present in soot and grime carried by
winds and deposited on buildings. One of the most common solvents is
carbon dioxide gas (CO2), which is always present in the air in some
amount. In country atmosphere it may not exceed 60 parts per million,
while in towns and cities, as determined by Warnes,^^ it may reach 450
parts per million. Carbon dioxide is a product of combustion of fuels,
therefore the atmosphere of large industrial cities contains the highest
proportions. Warnes's figure was determined in England in 1926 and
corresponds closely with figures given by Merrill'*^ in 1921 for several
American cities. Motor traffic was very much lighter during those
years than in American cities today, and it is probable therefore that
the average atmosphere of cities of the United States contains a higher
percentage of carbon dioxide than that given by Warnes.

Carbon dioxide gas is soluble in water to the extent of 1.796 per cent
at 0°C., and such solutions are slow solvents of some rocks. Both
calcium carbonate and magnesium carbonate are soluble in water satu-
rated with CO2, the former to the extent of 0.07 per cent, and the latter

48 Warnes, Arthur R., Building Stones, Their Properties, Decay, and Preservation.
Ernest Benn, Ltd., London, 1926, p. 172.

45 Merrill, G. P., Rocks, Rock- Weathering, and Soils. John Wiley & Sons, Inc.,
New York, 1921, p. 157.

350 THE STONE INDUSTRIES

0.113 per cent at 0°C. With calcium carbonate the following reaction
probably takes place: CaCOa + H2O + CO2 = Ca(HC03)2. Calcium
bicarbonate or acid carbonate thus formed is relatively soluble in a
carbon dioxide solution and consequently carried away. This slow
dissolving action accounts for the prevalence of caves in limestone and
dolomite rocks in regions where carbonated-water springs abound. It
is extremely slow in sound, close-grained limestones and marbles and
more rapid in those of open, porous texture.

The sand grains of some sandstones are cemented together with
calcium carbonate, and such rocks are likewise disintegrated slowly by
solution of the cement in carbonated waters. Carbon dioxide in solution
reacts similarly on mortars and cements, particularly those containing
free lime.

Sulphur dioxide (SO2) is another important product of fuel com-
bustion for many fuels contain sulphur compounds, especially pyrite
(FeS2), which oxidize and form fumes that are carried in the air. In
the presence of moisture they form weak solutions of sulphuric acid
(H2SO4), an agent much more active than H2CO3. When sulphuric acid
solutions come in contact with limestones or marbles calcium sulphate is
formed, according to the equation CaCOs -\- H2SO4 = CaS04 + H2O -f-
CO2. Under certain conditions the hydrous calcium sulphate, gypsum
(CaS042H20), is formed. Calcium sulphate is slowly soluble in water;
consequently, the surfaces of limestone or marble blocks are dissolved
slowly if exposed for a long time to an acid-laden atmosphere. Sand-
stones with calcareous cement are acted upon in much the same way.
Other acids, such as hydrochloric (HCl) and nitric (HNO3) sometimes are
present in the air in small quantities, and their solvent action is similar
to that of sulphuric acid.

Certain chemical salts, such as ammonium chloride (NH4CI) and
ammonium sulphate (NH4)2S04, are formed as products of fuel com-
bustion, and small quantities are present in rain water. When they go
into solution they are partly ionized or hydrolized and the acids thus
formed react as described in a previous paragraph.

Carbon dioxide, acids, and dissolved salts react on hornblende, feld-
spar, and silica in such rocks as granites, sandstones, and slates but only
to a slight extent, and much more slowly than on the carbonate rocks.

Alteration and Replacement of Minerals. — Alteration and secondary
mineralization of rocks are broad subjects on which entire books have
been written. The discussion herein is far from complete, being confined
to the more outstanding agencies and processes that cause deterioration
of building stones.

The changes that take place involve reactions between the constit-
uents of stone and chemical agents derived from external sources, chiefly
those carried by rain water. Hydration and oxidation are very common

PRESERVATION AND CLEANING OF STONE 351

processes, though many other chemical reactions occur. Hydration is
common, because many secondary minerals or chemical products are
hydrous sulphates, oxides, or silicates.

Oxidation alone may cause changes in color, with little or no detri-
mental effects. Thus, limestones containing ferrous carbonate may
be bluish white when first quarried but may change rapidly to buff or
yellow, chiefly through formation of limonite. Similarly, the sea green
slates of Vermont change to a rusty brown on weathering, but this change
in color is not regarded as an evidence of deterioration. Stonework,
however, may be damaged through oxidation. Oxidation of sulphides to
sulphates may result in swelling and consequent disruption. Oxidation
of ferruginous carbonates of calcium and magnesium, or silicates of the
mica, amphibole, and pyroxene groups may cause slow decomposition.
Many stones are disfigured with rusty stains produced by oxidation of
pyrite, marcasite, or other iron-bearing minerals. Oxidation of iron
sulphides may form weak solutions of sulphuric acid that will react on
certain constituents of stone.

The most damaging effects of the alteration and replacement of
minerals are due to increase in molecular volume of the new minerals
formed. Alteration of the original constituents of stone to new com-
pounds occupying greater space creates internal pressure that results in
disintegration. The most common substances that affect building stone
adversely in this way are calcium and magnesium sulphates. When
sulphuric acid comes in contact with a limestone either anhydrite (CaS04)
or gypsum (CaS042H20) is formed. The increase in volume when cal-
cium carbonate changes to anhydrite is in the ratio of 1 to 1.33; when it
alters to gypsum the change in volume is as 1 to 2.15. If calcium
sulphates thus formed crystallize within the stone the pressure of crystal
growth has a disruptive effect when space is insufficient. Calcium
sulphates are so slowly soluble in rain water that little relief from pressure
is to be expected through solution of the products of chemical reaction.

Sulphuric acid acting upon magnesium carbonate forms epsom salts
(MgS04.7H20), and the increase in volume is in the ratio of 1 to 5.3.
This remarkable change would be exceedingly detrimental were it not
for the easy solubility of magnesium sulphate in water. As it goes into
solution readily much of it may be carried away before it can crystallize
enough to cause serious disruption.

It is evident, therefore, that sulphuric acid in rain water may cause
some deterioration in limestones, dolomites, marbles, and calcareous
sandstones. Dense nonporous stones are affected but slightly, for reac-
tion occurs too close to the surface to cause disintegration by crystal
growth. Porous stone is damaged more seriously.

For reasons enumerated above slates having a considerable calcium
carbonate content are not to be recommended as roofing materials for

352 THE STONE INDUSTRIES

buildings exposed to acid fumes, for example, those near fertilizer plants,
because growth of calcium sulphate crystals between cleavage planes
causes rapid deterioration. Calcium silicates react in the same way
though much more slowly. The most enduring slates have a low calcium
content. Most igneous rocks, such as granites and diorites, contain
calcium and magnesium silicates and therefore are subject to the same
reaction in a degree, but their insolubility or slow solubility in weak acids
renders them more resistant than are the carbonate rocks. Nevertheless,
granite columns and exterior walls have been damaged seriously by acid
fumes.

Sodium chloride in sea spray may be deposited on stonework and its
crystallization cause damage at or near the surface; however, it is to be
regarded as a minor agent. Deterioration of monument bases and the
lower courses of stone buildings may be caused by soluble salts in the soil
carried upward by capillarity and drawn to the surface by evaporation.
Crystallized gypsum on or near the stone surface has been traced to this
source.

Detrimental effects resulting from crystallization of secondary com-
pounds are most noticeable in stones that have pronounced cleavage,
bedding, or foliation, because solutions usually enter cleavage planes with
relative ease. High-grade slate is an exception to this rule, for while it is
the most cleavable of all rocks it has a very low ratio of absorption.
Mica schists, micaceous sandstones, and thin-bedded or laminated
limestones may suffer in consequence of excessive absorption in the
direction of cleavage.

The Department of Scientific and Industrial Research in England
points out that decay results from close association of different types of
stone. For example, rapid decay of sandstone has been attributed to
the presence of calcium carbonate leached from adjacent limestone
courses. By contact with sulphur dioxide the carbonate in the pores
of the sandstone is changed to sulphate, and disintegration results from
increased volume of the sulphate.

Although attention has been directed to the more active chemical
agents of disintegration, certain slow weathering effects that have been
in operation for countless ages must not be overlooked. The change of
feldspar to kaolin, and of olivine to serpentine, as well as the alteration
of pyroxenes and amphiboles to epidote, chlorite, and sericite are well-
known processes of metamorphism. Such alterations in rock minerals
are exceedingly slow and therefore of little interest to the stone producer
or user in so far as deterioration after the erection of a building is con-
cerned. They are mentioned here primarily as a warning that precaution
should be exercised in the selection of stone. Buildings are exposed to
the weather not more than a few hundred years at most, but outcropping
ledges from which building stone may be obtained have been subject to

PRESERVATION AND CLEANING OF STONE 353

action of the weather for many thousands of years, and the effects may be
in evidence several feet below the surface. On this account, surface rock
usually is discarded as waste, for that which has already passed the earUer
stages of decay can not withstand exposure as well as fresh rock quarried
at depth. All competent quarry operators carefully avoid the use of
stone that shows signs of weathering.

The petrographic microscope is of inestimable value in studying
weathering of stone. In thin section under a microscope the beginning
of kaolinization of feldspar is shown by a cloudiness, while fresh, unaltered
spar is clear and colorless. Altered pyroxenes and amphiboles show stains
of iron oxide with traces of sericite and even calcite. Stone that shows
such definite evidences of alteration should not be used for structural
or ornamental purposes.

Changes or Agencies Chiefly Physical. Expansion and Contraction. —
With every change in temperature there is a slight change in volume of all
rock minerals. According to data compiled by Warnes^*' the amount of
expansion of a piece of granite 1 inch long for each degree Fahrenheit
increase in temperature is from 0.000004 to 0.000008 inch; for sandstone,
about 0.000009 inch ; and for marble, about 0.000006 inch. Such amounts
may seem too small to have any material effect, but when considered in
terms of blocks several feet long, and under variations of many degrees in
temperature, the change becomes more apparent. Thus, a block of
sandstone 5 feet long will expand about one-twentieth inch in length if its
temperature is raised from 0° to 100°F., and this amount may be sufficient
to cause minute fractures in mortar joints. It is claimed that Bunker
Hill monument, a hollow obelisk of granite 221 feet high and 30 feet square
at the base, is measurably affected by expansion, for the top oscillates
about one-half inch from morning to evening on a sunny day. During
a visit some years ago to granite quarries on the coast of Maine the
WTiter was informed that thin sheets of granite 50 or 60 feet long which
are fast at the ends and so incapable of lateral expansion would arch
upward at the center at least 2 inches on a cloudless day in midsummer.
Fire setting has been used quite commonly as a substitute for explosives.
Certain native races, for example those in some parts of India, build fires
on granite surfaces and then throw water on the heated rock to cause
spalling by sudden contraction of the surface; sheets thus obtained are
used for structural purposes. The above illustrations indicate that
expansion and contraction are important enough to warrant attention.

A few changes in temperature from hot to cold might have little or
no effect on the quality of stone, but in climates subject to extreme diurnal
and annual temperature changes, repeated expansion and contraction
have a weakening effect. Stone is made up of countless crystals or grains

*" Wames, A. R., Work cited, p. 161.

354 THE STONE INDUSTRIES

closely packed together, and with increase in temperature each grain
expands and crowds against those surrounding it. As the temperature
falls contraction occurs, with consequent tendency to create infinitesimal
seams which may be enlarged by infiltration of solutions and crystal-
lization of salts. As rocks are poor conductors of heat, surface layers
may be subject to much greater changes than the interior, and unequal
strains thus created may intensify disruptive effects. Furthermore, the
coefficient of expansion of crystals varies with direction; thus, a mineral
grain may expand more in one direction than in another with consequent
unequal strain.

Igneous rocks such as granites consist of a variety of minerals each
of which has its own coefficient of expansion. Quartz, for example,
expands about twice as much as orthoclase for the same change of tem-
perature. Variations in temperature of rocks of heterogeneous com-
position are therefore more detrimental than similar changes in rocks
consisting largely of one mineral. Granites and other igneous rocks
usually suffer more from repeated excesses of heat and cold than do
limestones, marbles, and sandstones.

Obviously, stone is more enduring in climates where diurnal and
seasonal temperature changes are slight than in regions subject to exces-
sive heat and cold. The equable, warm climate of Egypt has preserved
its great obelisks and pyramids remarkably well. A uniformly cold
climate is also favorable for rock preservation. While engaged in geo-
logical survey work on the Hudson Bay slope of northern Canada the
writer was greatly impressed with the remarkable preservation of granite
exposed for countless seasons since the glacial period; no doubt, this
condition is due in some measure to the fact that changes of temperature
are moderate. In Great Britain and in many eastern and central
European countries climatic changes are not so excessive as in many
parts of the United States, and buildings made of stone are relatively
more enduring. In eastern and northern sections of the United States
temperatures are subject to extreme changes that have relatively severe
effects on exposed stonework.

The foregoing statements must not be interpreted to indicate that the
life of stone buildings in many parts of the United States is short.
Although expansion and contraction are factors that deserve careful
attention, their effects on high-grade stone are extremely slow. Other
types of building materials suffer as much and probably more than stone
from severity of the climate.

Frost Action. — In the preceding discussion of the action of heat and
cold no consideration was given to effects of low temperature on water
contained within stone. In freezing, water expands about one tenth of
its volume, and pressure exerted by this expanding force is so great that
no stone is strong enough to withstand it. Consequently, if the pore

PRESERVATION AND CLEANING OF STONE 355

space is filled completely with water and the temperature falls below
freezing some degree of disruption will occur. If the pores are only
partly filled with water, leaving at least one eleventh of the space empty,
necessary expansion may take place without fracturing. The more nearly
complete the saturation the more serious the effect will be.

Most freshly quarried stones, especially limestones and sandstones,
are almost if not entirely saturated with "quarry water," and the effects
of frost on saturated blocks are very serious. Such stone is rarely
quarried during the winter, for blocks must have at least several weeks
to dry out before they are safe from frost action. However, it is impor-
tant to note that when once the quarry sap has been dried out danger
of serious damage by frost is past, even though soaking rains occur
immediately before a heavy frost. Subsequent wetting evidently fails to
bring about complete saturation, and enough pore space is left for normal
ice expansion.

Detrimental effects of the action of frost have been exaggerated by
some writers, probably because they judged effects observed on freshly
quarried stone rather than on seasoned blocks. No doubt frost is a con-
tributory cause of disintegration, but only in exceptional cases where
saturation is nearly complete. Usually only one face of stone is exposed
to the weather, and water which falls on the exposed face gradually passes
inward to the dry interior. Rain seldom continues long enough for
complete saturation, and frost rarely follows rain so closely that enough
time has not elapsed for at least partial drying.

The most porous stone is not necessarily the one most seriously
affected by frost because usually it gives up its water content readily,
particularly if the openings are comparatively large. Stone with sub-
capillary pores, even though it has a low ratio of absorption, may be the
most seriously damaged, because capillary action tends to keep the pores
filled or nearly filled with water.

A uniformly cold winter climate is less detrimental in this respect
than one characterized by repeated rain and frost for, just as many
succeeding expansions and contractions have a weakening effect, so
innumerable repetitions of minute frost fractures lead to deterioration.

The effects of frost do not depend solely on porosity. Incipient
seams may fill with water, and frost will widen them. Laminated rocks
may scale badly if water freezes in loose bedding planes. Complete
destruction of stonework has resulted from placing blocks with their
cleavage or bedding vertical, a position most favorable for spalling by
frost if water is absorbed between the laminations. Limestones with
shaly layers or any stones with seams that absorb water readily are not
regarded favorably in regions where frost action is severe.

Abrasion. — Certain types of stonework, such as floor tile, walks, sills,
and steps, are subjected to the wear of footsteps. In the concourses of

356 THE STONE INDUSTRIES

railroad stations, in corridors, lobbies, and on stairs of public buildings
abrasion may be so intense that stone may be worn down an inch or more
after many years of service. For such uses varieties that are known to
be resistant to abrasive action are usually selected. Coarse-grained
saccharoidal marbles, soft slates and limestones, and loosely cemented
sandstones generally are avoided. Fine-grained dense marbles, silicated
marbles, travertine, some varieties of slate, the harder types of soapstone,
bluestone, indurated sandstone, and granite all have given excellent
service for flooring and steps. Intelligent selection can be made best
after abrasion tests are applied. Relative resistance to abrasion can be
determined by bringing the various stones in contact with a grinding
wheel or disk and weighing the cuttings obtained after a definite number
of revolutions under uniform pressure. Those that give the smallest
weight of cuttings are best adapted for uses where they are exposed to
excessive wear.

Cutting or attrition of sand, sharp coal clinker, or other granular
matter carried by wind is another form of abrasion that definitely reduces
the surface of exterior building stone. The wearing and polishing effects
of wind-blown sand are observable on many natural rock exposures.
Projections are worn to rounded shape, soft spots and bands are cut into
grooves and hollows, and surfaces become polished. In southwestern
Minnesota the action of wind on exposures of quartzite has rounded and
polished them until they have the appearance of lava or glass. Dust
storms in the arid or semiarid sections of the Southwest have similar
abrading effects. The battered face of the Sphinx and the fantastically
carved natural monuments in the Garden of the Gods are classic examples
of aeolian abrasion.

In towns and cities wind-borne particles consist principally of dust
from streets or roads and soot or clinkers from stacks and chimneys. In
country regions sand grains are carried from roads, fields, and hillsides.
The abrasive action tends to be most severe in shore or coastal regions,
where beach or dune sands are plentiful and where winds are more prev-
alent and attain higher velocity than at interior points.

Wind action on stone buildings is most intense close to the ground,
particularly on corner blocks where air currents converge and wind pres-
sure is high. Abrasion is most noticeable on walls facing the direction
of prevailing winds. Stone carved in relief may be worn sufficiently to
impair its effectiveness. Inscriptions on monuments in old cemeteries
may become obliterated if they face the direction of prevailing winds.
Pits and grooves may be formed where soft spots or bands occur. Deep
pits may contain sand grains that are carried round and round by air
currents wearing the holes larger in the same manner that pot holes are
formed in stream beds. While wind action is a minor cause of injury to
stonework, it is sufiiciently important to merit care in the selection of

PRESERVATION AND CLEANING OF STONE 357

wear-resisting material for corners and surfaces exposed to unusual
abrasion from that source.

Settlements. — Poor foundations or badly built walls may cause frac-
tures in stone of the highest quality. Door and window caps or sills are
commonly fractured, not as a result of seams or weaknesses in the stone,
but because they were improperly placed or subjected to unequal strain
or because foundations have settled causing a downward movement of
certain parts of the wall. Many stone walls that should have existed in
good condition for a long period are fractured beyond repair because of
settling foundations. Unequal pressure, owing to faulty design, is a
contributory cause.

Causes Both Chemical and Physical. Plant Growth. — Lichen and
moss growths are common on monuments in many cemeteries and on old
stone buildings, particularly on their shady sides. All lichens that grow
on stone are not of the same character. Granites have types that prefer
an acid environment, while limestones nurture entirely different varieties
that subsist on more basic materials.

Lichen growth is not to be regarded as an evidence of stone decay,
for these remarkable little plants have the power of disintegrating per-
fectly fresh, solid rock in obtaining food supplies. Nor do they depend on
microcrevices for a foothold ; botanists have found that they can penetrate
the hardest rocks, even silica. However, the hyphae or rootlets of the
fungus portion of lichens may more readily enter small fractures caused by
surfacing machines or hand tools used in dressing stone.

The influence of plant growth on building stone is both mechanical
and chemical. Root pressure gradually widens openings and causes small
particles to fall away, and lichens secrete organic acids that have a mild
corrosive effect, particularly on limestones, dolomites, and marbles.
Lichens also retain moisture, soot, and grime on the surface of rock, thus
aiding the action of solvents and possibly increasing the effects of frost.
Ivy and creepers, although adding beauty to masonry structures, keep
walls moist and secrete acids that have a mild solvent effect. After
attaining a heavy growth, ivy inserts filaments between the stones, which
by enlargement slowly impair the integrity of the wall. The claim has
been made that bacteria are effective agents of stone decay, but they are
probably of minor consequence.

Marine Borers. — Breakwaters, docks, harbor walls, and other sub-
aqueous stone structures are damaged at times by certain rock-boring
molluscs, such as pholas and lithophagus. They penetrate limestone,
sandstone, or granite and may so impair walls that replacement becomes
necessary. Boring is effected by chemical rather than by mechanical
means.

Faults in Accessory Materials and Workmanship. — The quality and
permanence of stonework depend to quite an extent on workmanship and

358 THE STONE INDUSTRIES

choice of supplementary materials. Defective roofs, gutters, and flash-
ings or badly constructed window casements may permit water to soak
into parapets or run behind stone facing blocks. Unsightly stains may be
caused by the attachment of iron or steel bars to stone. The rusting of
iron to iron oxide is accompanied by great expansion, and pressure exerted
by a rusting iron bar closely fitted into a hole in stone may be enough to
burst the block. Lead joints have been known to stain polished monu-
mental marble.

Masonry mortars or cements are very important supplementary
materials used with building stone. Open joints between blocks of stone
caused by faulty mortar, or by use of too small an amount, are highly
undesirable as they permit access of water or injurious solutions. Accord-
ing to Anderegg,^^ properties of mortars that demand special attention
are, in order of their importance: Workability, bond strength, water-
tightness, weather-resistance, flexibility, shrinkage, compressive strength,
and freedom from efflorescence. Trainor^- expresses the properties
somewhat differently and lists them in order of their importance as
follows: Plasticity, adhesion, volume changes after hardening, elasticity,
resistance to frost, freedom from efflorescence, rate of hardening, absorp-
tion, and strength. Lime mortars, portland or natural cement mortars,
and mortars containing both lime and cement are all used. Lime has
properties that make it highly desirable, and cement has quite different
qualities that are also advantageous in masonry mortars. These proper-
ties may be regarded as supplementary to each other, and for this reason
many stonesetters prefer mortars containing both lime and cenient.
There are now on the market more than 40 masonry cements or mortars,
ranging in composition from those with a major lime content to those in
which the proportion of cement predominates. Mortar of any type
should have a minimum content of soluble calcium or magnesium salts,
as these may produce unsightly surface efflorescence. The nature and
qualities of materials entering into a mortar are of minor importance,
provided the desired properties of the finished product are attained.
Much detailed information is to be found in the articles mentioned in the
footnotes.

The importance of this subject has been duly recognized by the
American Society for Testing Materials which in 1932 established a
representative committee designated "C-12 on Mortars for Unit
Masonry." The principal object of the committee as expressed at the
time of its organization is ''Research to promote knowledge of properties

^1 Anderegg, F. O., Analysis of Properties Desired in Masonry Cements. Rock
Products, vol. 34, no. 25, 1931, pp. 40-42. Lime and Portland Cement for Masonry
Mortars. Rock Products, vol. 35, no. 4, 1932, p. 46.

" Trainor, Leo S., Fundamental Properties of Mortar for Durable Unit Masonry.
The Clay Worker, vol. 97, no. 5, May, 1932, pp. 250-253.

PRESERVATION AND CLEANING OF STONE 359

and tests of mortars for unit masonry, and development of methods of
test and specifications for such mortars."

Weathering Effects on Stones of Various Kinds. — In summarizing
weathering processes covered in preceding paragraphs some general
conclusions may be reached regarding the relative effects of various
agencies on different varieties of stone. Carbonate rocks (limestones,
dolomites, and marbles) are altered chiefly by chemical action, and to a
much smaller degree by physical agencies. Solution and slow disintegra-
tion on account of the expansion of alteration products are the chief
causes of deterioration in rocks of this type. They are, however, little
affected by expansion and contraction owing to temperature changes,
and fine-grained impervious types suffer only to a small extent by frost
action. Fine-grained limestones withstand the effects of fire remarkably
well up to the point of calcination.

As compared with carbonates the effects of weathering agencies on
granites, syenites, and similar igneous rocks are reversed in importance.
Their disintegration is brought about chiefly by physical agencies, the
most important of which are repeated expansion and contraction resulting
from variations in temperature, although igneous rocks are generally as
resistant as carbonate rocks to the effects of frost. Also, granites and
similar rocks spall badly if the building in which they are used is burned.

Few general rules can be established for sandstones, because they are
quite variable in character. Those with calcareous cement are affected
chemically in much the same way as limestones and marbles. Porous
sandstones are subject to disintegration by frost if they do not give up
included water freely. Diurnal expansion and contraction have little
effect. Firmly cemented siliceous sandstones probably are more resistant
to weathering than other ordinary building stones.

Slates are affected very little by solution, although a high calcium
content may lead to early disintegration if they are exposed to acid fumes
or solutions. Expansion and contraction affect them slightly. As noted
in the slate chapter, some high-grade American roofing slates show
scarcely any weathering effects after exposure for 100 to 200 years.

Importance of Care in Selection of Stone. — As stated in a previous
chapter, man can not change the quality of stone, but he has the power
of selection. Ability to select wisely depends on fundamental knowledge
of building stone, full comprehension of architectural demands, and an
adequate understanding of the agencies already mentioned that tend to
mar or weaken stone and to which the finished structure may be exposed.
For instance, white marble or granite might not be suitable in an industrial
city with smoke-laden atmosphere. Climatic conditions should also be
considered. Porous shell limestone that will endure many years in the
chmate of Bermuda would disintegrate rapidly in the Middle Atlantic
States. Consideration must also be given to the direction of prevailing

360 THE STONE INDUSTRIES

winds, which may carry polluted air from factories or chemical plants.
Structures exposed to winds bearing corrosive gases should be made of
stone that exhibits high resistance to chemical action.

PRESERVATION OF STONE

Preservatives. — A desire to maintain the integrity of ancient stone
buildings showing evidences of deterioration has led to the use of preserva-
tives with which to treat the surfaces to prevent further decay. Naturally,
this work has been done more in Europe, where the buildings are older
than in America. In England, especially, much study and experimenta-
tion have been devoted to the nature and effectiveness of various preserva-
tives and to methods of application. Warnes^^ has presented an excellent
review of the principal compounds employed and has pointed out their
respective merits.

An ideal preservative must satisfy a number of exacting requirements.
It is a solution applied to the surface of stone, the solid part of which —
the actual preservative — remains as a coating upon evaporation of the
solvent. The solution should penetrate some distance below the surface,
and quite a number of applications may be necessary to accomplish this.
It must be so noncorrosive that it will not affect the stone and sufficiently
resistant to weathering action to retain its effects a long time. It
should cause no noticeable staining or discoloration of the natural sur-
face; most reagents used change the color to a slightly darker shade. It
must prevent penetration of moisture and at the same time allow it to
escape. The latter condition seems paradoxical and is contrary to the
opinions of many that preservatives should seal the surface watertight.
Such sealing is highly desirable as a preventive of decay from absorbed
solutions and would be entirely feasible if stone were absolutely free of
moisture. It is impossible, however, to attain perfect dryness in a wall
already built and exposed to the weather, and if the surface of stone con-
taining moisture is sealed the pressure of water vapor and the crystalliza-
tion of salts beneath the coating will gradually result in deterioration.
It seems desirable to so treat the surface that the pores are not completely
closed; thus, escape of moisture is permitted and at the same time a
surface is obtained which will prevent moisture from passing into the
stone by capillary action. The latter condition may be attained by using
materials having high water-repellent properties. Waterproofing
materials should also be easy to apply and should be reasonably cheap.

Warnes has given careful consideration to preservative materials
of many kinds, including linseed oil, china-wood oil, liquid paraflSn,
petroleum jelly, paraffin wax, mineral soaps, resins, glue, animal fats,
cellulose compounds, and silicofluorides, and has come to the conclusion
that paraffin wax dissolved in light petroleum distillate or coal-tar

'•^ See bibliography at end of chapter.

PRESERVATION AND CLEANING OF STONE 361

naphtha is the best. The solution should contain no undissolved wax at
a temperature as low as 45°F., but at the same time it should not be too
dilute. Kessler,^* of the United States Bureau of Standards, ran a
series of tests of waterproofing materials covering two years. He found
that heavy petroleum distillates, fatty oils, and insoluble soaps were the
most effective materials; paraffin gave the highest waterproofing value
and appeared to be the most durable. He also found that the effective-
ness of waterproofing is influenced greatly by the character of pores; as
stones wdth minute pores are more difficult to waterproof than those
with large ones. As a result of experiments recently conducted at the
University of Manchester, England, it has been found that a new pre-
servative called "Cephasite" gives excellent results. The nature of the
compound has not been revealed.

A lime wash prepared by mixing hydrated lime with water has been
used for several centuries as a stone preservative. Usually some other
ingredient, such as salt, tallow, milk, or casein, is added. A coloring
agent may be used to simulate the appearance of the structure to which
the wash is applied. Carbon dioxide in rain water gradually converts
the lime into calcium carbonate. No doubt it is protective to some
extent, but it has serious disadvantages. The finely divided lime is
readily acted upon by acids, forming calcium sulphate which, as previously
pointed out, is one of the chief agents of stone decay. When binding
materials are added to the wash the surface may be completely sealed,
which results in trouble from included moisture. Repeated applications
may form a heavy coating that is liable to break off in cakes or patches.
In any event, a lime wash is not an attractive finish for large and stately
buildings, although it may be reasonably effective and not unsightly if
applied every one or two years to cottages or farm buildings. It is very
commonly applied to Bermuda coral limestone used both in walls of
houses and as roofing slabs.

Waterproofing compounds are commonly applied to surfaces other
than those exposed to prevent absorption and staining from brickwork,
mortar, cement, structural steel, or other metal parts. As faces thus
treated are all hidden, waterproofing compounds may be black or any
other color.

Consolidating Processes. — If stone has already partly decayed a first
step in its preservation is to consolidate the loosened particles. Silica
applied as an alcoholic solution of silicon ester is, according to present
knowledge, the material most satisfactory for this purpose. It decom-
poses in the presence of moisture, depositing silica and setting free
ethyl alcohol. The precipitated silica acts as cementing material for
loosened grains, and covers all particles with a thin film. The alcohol
evaporates and has no injurious effects. For best results application

^* See bibliography at end of chapter.

362 THE STONE INDUSTRIES

must be made by an experienced workman. Other consolidating
materials, such as sodium silicate (alone or with acids or calcium chloride),
hydrofluosilicic acid, silicofluorides, barium hydrate, resin, metallic salts
of fatty acids, and solutions of shellac either cause efflorescence or rock
corrosion or are detrimental in other respects.

Normally, the consolidating process is followed by one of the water-
proofing processes previously mentioned. When a preservative is
applied before decay begins the consolidating process may be omitted.

General Considerations. — As may be inferred from the preceding
paragraphs, w^eatherproofing is difficult both in selection of materials and
in technique of application. It may become a necessary step for the
preservation of historic edifices, but probably never will be found satis-
factory for general use. The difficulties and limitations of artificial
preservation emphasize the inestimable importance of selecting for
exterior use in monumental buildings the very highest grades of weather-
resisting stone. The fact that fair success has been attained in the
application of preservatives is no excuse for using stone of inferior
quality for noble structures.

CLEANING STONE

Necessity for Cleaning Process. — The surface of stonework gradually
becomes soiled from external causes. Grime may accumulate rapidly
in smoky industrial cities, although stone may remain comparatively
clean for many years in the open country or in towns and cities where
little soft coal is used. The lower courses of stone buildings are exposed
to many agencies which soil and discolor. Tombstones and monuments
are commonly coated with lichens or with wind-blown soil or soot. Their
surfaces may also be stained with solutions carried upward by capillarity
from the soil or from cementing materials at the base. Many building
stones exhibit characteristic individuality, and their distinguishing
features are lost when the surface becomes coated with foreign material.
To renew the surface that it may in some measure present its original
appearance requires some process of cleaning, which is also a necessary
step preparatory to any process of preservation.

Polished stone accumulates dirt less readily than unpolished surfaces
and is also very easily cleaned. Although polished surfaces are expensive,
they are chosen for the base courses of many large buildings because of
their attractiveness and cleanliness.

Although innumerable large stone buildings sooner or later require
some cleaning process, at times cleaning is detrimental rather than bene-
ficial. The mellowing influence of time is a beautifier of architectural
stonework. Old buildings may be neither stained nor disfigured, their
color tones being merely softened and harmonized with the surroundings.
Many Americans sadly lack appreciation of an atmosphere of antiquity

PRESERVATION AND CLEANING OF STONE 363

and seek newness at the expense of that attractiveness which weather-
ageing alone can supply.

Cleaning Methods. — Methods of cleaning stonework may be classified
in general as follows:
Dry processes

Working to a new face

Sand blasting

Wire brushing

Rubbing wdth Carborundum block or grit stones

Heating with blow torch
Wet processes

Scrubbing with water only

Scrubbing with various solutions and abrasives

Applying acids

Steam cleaning
Dry Processes, working to a new face. — ^Dressing a face with
stone masons' tools presents a new surface, but it demands skilled labor
and is therefore very expensive and usually unnecessary. The original
surface of a stone block, case-hardened to some extent by crystallization of
salts contained in quarry sap, is harder than any subsequent surface, and as
redressing removes it the new surface is less durable than the original.
As reworking is both detrimental and expensive it is rarely employed.
SAND BLASTING. — The sand-blast method is used widely for renovating
soiled stone-work but is entirely too severe in its effects to be recommended
as a cleansing agent. A sand blast removes grime by carrying away the
stone particles to which soot or soil adheres. It has the same dis-
advantage as working down the surface with tools, namely, removal of the
original hard surface. Sand blasting also rounds off sharp edges and
disfigures fine carving.

WIRE BRUSHING. — A wire brush sometimes is used to clean stone sur-
faces but is unsatisfactory, as it removes only loose soot and grime or
loosened particles of decayed stone. The softer stones may be brushed
to a fairly clean surface, but the harder varieties, with closely adhering
dirt or stains, cannot be cleaned effectively by this method. Moreover,
awkward corners and angles around cornices, moldings, or carvings
cannot be reached easily with a brush. Wire brushing may also cause
stains from the rusting of specks of iron left on the stone surface.

RUBBING WITH CARBORUNDUM BLOCK OR GRIT STONE. Rubbing down

with dry abrasive stones is so ineffective that it is rarely used. It
presents difficulties similar to those of wire brushing, namely, inability
to obtain a clean surface and to work in narrow spaces and corners.
HEATING WITH BLOW TORCH. — Heating a stone surface with a blow
torch and brushing away loosened fragments of stone is about the most
abusive method of cleaning that could be devised. Excessive heat

364 THE STONE INDUSTRIES

applied unevenly scales and disintegrates the surface, leaving it in bad
condition for resisting weathering effects.

Wet Processes, scrubbing with water only. — A scrubbing brush
and hot or cold water are used frequently for cleaning stone. Although
superficial dirt may be removed thus the process has little or no effect
on closely adhering soot or grime caked on the surface. It also fails to
remove foreign matter which enters the pores of stone,

SCRUBBING WITH VARIOUS SOLUTIONS AND ABRASIVES. Pumice,

diatomite, sand, stone dust, or other abrasives are used with water for
scrubbing surfaces of stone, and while more effective than pure water
they are far from satisfactory. Various reagents dissolved in water are
also used. Some are fairly effective, but quite a few are injurious if not
used carefully. Some of the more common reagents that demand
judicious use are discussed briefly.

CAUSTIC SODA. — Caustic soda (NaOH) dissolved in water is com-
monly used alone or in conjunction with sand or other abrasive for
scrubbing stone surfaces. Strong caustic soda may have corrosive or
disintegrating effects, particularly on carbonate rocks. Carbon dioxide
in the atmosphere changes it to soda carbonate, and sulphur dioxide may
alter it to sodium sulphate. Both changes involve increased molecular
volumes, and if such reactions take place in porous stone that has absorbed
the solutions, surface disintegration may result. If employed at all this
reagent should be used with great care.

SOAP SOLUTIONS. — Soap, with or without dissolved salts or abrasives,
is widely used. Soap solutions are subject to slight hydrolization into
acid soap and free alkali, usually caustic soda, the effect of which has
already been mentioned. If strong soap solutions are used they should
be thoroughly washed from the surface.

ACIDS. — Hydrochloric and hydrofluoric acids sometimes are employed,
but their use should be discouraged. The effects of acids on stonework
have been covered in an earlier part of this chapter dealing with deteriora-
tion. Although they may be effective as cleansing agents they corrode
and discolor the stone. Discoloration is due largely to chemical reac-
tions with iron-bearing constituents of the stone. Acetic acid is milder
in its action.

Special Cleaning Methods. — Much experimentation and research have
been conducted on cleaning processes, and as a result stone associations,
Government bureaus, or private companies have worked out formulas or
have prepared special compounds which they recommend as effective and
harmless. Several proprietary compounds are on the market and are
advertised in stone-trade journals.

Methods of Cleaning Limestone. — The following method has been
recommended for cleaning limestone : The equipment required is a steam
boiler capable of producing steam at 150 pounds pressure, and two sets

PRESERVATION AND CLEANING OF STONE 365

of hose, one for steam and one for water. Cold water and steam at high
pressure are mixed in a special nozzle, and the result is a spray of very-
hot water impinging on the stonework at high velocity. This dissolves
and carries away the soot, grease, and dirt. It is claimed that hot water
is more effective than steam, but this is doubtful. Where this method is
not practical the surface of the stone may be scrubbed with an ordinary
fiber brush and any white soap powder dissolved in soft water.

For oil, rust, smoke, and other stains not over a year old and not dried
deeply into limestone the following method was recommended some years
ago by the Indiana Limestone Quarryman's Association ; Wash the stone
with a solution of 2 pounds of oxalic acid in 1 gallon of water, allowing
time for it to soak in; then spread over the face of the stone to a depth of
one sixteenth inch a paste made by mixing 3 pounds of chloride of lime
with 1 gallon of hot water; leave the paste in contact with the stone for 24
hours; if upon its removal the stains have not disappeared, repeat applica-
tion of paste several times if necessary.

For removal of cement stains a mixture of chloride of lime and potash
in equal quantities is recommended. Enough plaster of paris should be
added to make a putty, which is applied to the stone and allowed to stand
for a week or longer. A layer one half inch thick of hot-lime putty is
also recommended. It should be left on the surface of the stone for
several days.

Methods of Cleaning Granite. — The following methods of cleaning
granite surfaces have been worked out by the United States Bureau of
Standards : Ordinary accumulations of dirt may be removed by scrubbing
with a stiff fiber brush and a grit cleaning powder and warm water. The
stone surface should first be soaked thoroughly with clean warm water,
the brush dipped in water and then in the dry powder, and applied to the
surface with vigorous scrubbing. Suitable powders may be purchased
under various trade names such as "Old Dutch Cleanser," "Marbhca,"
or "Wyandotte Detergent."

Lichens or moss growths on granite may be removed with a caustic
solution of 3 or 4 tablespoonfuls of ordinary lye in 1 gallon of water
applied with a stiff fiber brush. The treatment should be preceded and
followed by thorough washing of the surface with clean water.

Stubborn cases of soiled granite usually may be cleaned with ammonium
fluoride or ammonium bifluoride solutions made by dissolving about one
half pound of the crystals in 1 gallon of warm water. Such solutions etch
granite to some extent and hence should not be used on polished surfaces.
They should be applied after a preUminary wash with clear water, left on
the surfaces only long enough to give desired results, and then thoroughly
rinsed off.

Stains that have penetrated the surface and which cannot be removed
by the last-named process require special treatment. Generally the

366 THE STONE INDUSTRIES

method of treating stains on interior marble, which is described in a
later part of this chapter, may be applied with equal success to granite.

Steam Cleaning. — A steam jet for cleaning stone has been used generally
during recent years. Steam is generated in a portable boiler placed near
the building to be cleaned and is carried to any desired point through
flexible metallic hose. A boiler pressure of 40 to 60 pounds a square inch
is maintained, but the effective pressure of the steam as it reaches the
stone surface is very much less. Warnes, in the book previously cited,
estimates it at 1}4, to 2 pounds a square inch, a force too weak to wear
the stone, though it will carry away loose particles. Cleaning with steam
is the most satisfactory method yet devised. Not only is it effective
in removing dirt, but a steam jet is easy to direct into all corners, into the
intricacies of carvings, or into narrow places that are difficult to clean by
scrubbing processes. Furthermore, if properly conducted the process
is not injurious to stone. Some complaint has arisen, because in an
effort to speed up the cleansing process strong reagents, such as caustic
soda or acids, are used in conjunction with steam, but such unwise
accessory treatment should in no sense condemn steam cleaning.

While steam cleaning is effective for ordinary dirt it will not always
bring back the original color to the surface, because iron stains resulting
at times from alteration of iron-bearing minerals in the stone may be
deep-seated and difficult to remove. For the more tenacious discolora-
tions scrubbing with chemicals before steam cleaning may be necessary,
but care should be exercised in choice of reagents.

Maintenance of Interior Marble. — Stone used for interior structural
or decorative purposes, while not exposed to the weather, is subjected to
many soiling and staining agencies. Floors, particularly, require frequent
cleaning. Iron rust, tobacco, ink, oil, and various other stains may
require special treatment. Kessler^^ has made a very exhaustive study
of the maintenance of interior marble, and his conclusions are worthy of
brief review. Many of the methods proposed may be applied with equal
success to the treatment of stains and discolorations on other kinds of
stone.

Kessler found that commercial cleaning preparations fall into two
classes — a scouring type containing abrasive powder, usually volcanic
ash, and a nonscouring type consisting of soap or alkali salts. Scouring
powders are not appreciably injurious to floors or other unpolished marble
but should not be used on polished work. The lower part of polished
baseboards is often injured by contact of mops and brushes used in
scouring floors. Soapstone and talc grits will not injure polished marble.
A preparation consisting of 90 per cent soapstone and 10 per cent soap
powder is effective and satisfactory for cleaning either marble floors or
polished surfaces.

^^ See bibliography at end of chapter.

PRESERVATION AND CLEANING OF STONE 367

Injury to marble work may result from frequent use of such detergents
as sodium carbonate, sodium bicarbonate, or trisodium phosphate used in
nonscouring compounds. The effect is physical, owing to crystallization
of salts in the rock pores. Marble work may be safely cleaned by such
compounds if the surface is j&rst rinsed with clear water. Although soap
is sometimes objectionable it gives satisfactory service if used with soft
water. Ammonia water, acids, and preparations containing coloring
ingredients should be avoided.

Interior marble sometimes is stained when in contact with damp walls,
because moisture dissolves salts from masonry and slowly deposits them
in the stone. Marble slabs may be protected from such effects by water-
proofing the back of the slab before it is installed. Molten parafl&n
driven into the pores by heat is an effective sealing agent.

Treatment of Stains. — Stains that have penetrated marble usually re-
quire poultice treatment . No one method is applicable to all kinds ; most of
them require special methods. Kessler's recommendations for the more
common types of stains are given briefly, as they apply also in a gejieral way
to other types of rock. Details of treatment may be found in his^ech-
nologic Paper 350, mentioned in the bibliography at the end of this chapter.

For removing mild iron stains dissolve 1 part of sodium citrate in 6
parts water, add an equal volume of glycerin, mix thoroughly, and add
whiting to form a paste. Apply it to the stained surface and leave for
several days, repeating the treatment if necessary. For deep iron stains
sodium hydrosulphite (Na2S204) may be used; the surface should first
be soaked with a solution of sodium citrate.

Green or brown stains from copper or bronze may be removed with a
poultice made by mixing in dry form 1 part of ammonium chloride
(sal ammoniac) with 4 parts of powdered talc and adding ammonia water
to form a paste. A solution of 8 ounces potassium cyanide in 1 gallon of
water is also recommended, but this is a very poisonous solution that must
be handled with great care.

Ordinary ink stains may be treated with a strong solution of sodium
perborate dissolved in hot water, to which is added enough whiting to
make a thick paste. It is apphed in a layer one-fourth inch thick and left
until dry.

Tobacco stains usually can be removed with a paste made by mixing
any of the ordinary grit scrubbing powders with hot water.

For oil stains cut a piece of white canton flannel somewhat larger than
the stain and saturate it with equal parts of acetone and amyl acetate.
Place it over the stain and cover with a piece of glass or a slab of marble.
The cloth should be resaturated several times. For surface oil stains
that have not penetrated deeply into the stone nor oxidized, benzol or
gasoline may be mixed with hydrated lime, marble dust, or whiting to
make a paste which is plastered over the stain.

368 THE STONE INDUSTRIES

Linseed-oil stains from putty are difficult to remove, and several
methods are recommended. Repeated applications of hydrogen peroxide
may be effective, or a special poultice may be used. It consists of 1 part
of trisodium phosphate, 1 part of sodium perborate, and 3 parts of
powdered talc made into a paste by adding a strong soap solution.
Repeated applications of the paste may be necessary. To prevent
occurrence of linseed-oil stains substitution of grafting wax for putty is
recommended where plastic material is required to fill around pipes or for
other applications in contact with marble.

General service stains embrace dingy or yellowish effects due for the
most part to improper or insufficient cleaning. They may usually be
removed by scrubbing with javelle water or by poulticing with commercial
grit scrubbing powders.

The following method of removing fire stains from stone was given
by an English writer in 1931: To 1 gallon of soft soap add 2 pounds of
finely powdered pumice and 1 pint of liquid ammonia. After mixing
thoroughly apply with a fiber brush. Allow to remain on the stone 30
or 40 minutes and then rub the surface briskly with a sponge or scrubbing
brush dipped occasionally in clean warm water.

Bibliography

Behre, C. H. The Weathering of Slate. Proc. Am. Soc. Test. Mat., vol. 31, pt.

II, 1931, pp. 768-774.
Brightly, H. S. Economic Aspects of Masonry Decay from Weathering. Proc.

Am. Soc. Test. Mat., vol. 31, pt. II, 1931, pp. 716-724.
Federal Board for Vocational Education. Stone Setting; the Setting of Cut-stone

Trim in Brick Buildings. Bull. 106, 1927, 114 pp.
Kessler, D. W. Exposure Tests on Colorless Waterproofing Materials. Bur. of

Standards Tech. Paper 248, 1924, 33 pp.
■ A Study of Problems Relating to the Maintenance of Interior Marble.

Bur. of Standards Tech. Paper 350, 1927, 91 pp.
Weathering Test Procedures for Stone. Proc. Am. Soc. Test. Mat., vol.

31, pt. II, 1931, pp. 799-803.

Bibliography on Weathering of Natural Stone. Proc. Am. Soc. Test. Mat.,

vol. 31, pt. II, 1931, pp. 804-813.
Kessler, D. W., and Sligh, W. H. Physical Properties and Weathering Character-
istics of Slate. Bur. of Standards Research Paper 477, 1932, 35 pp.
LotiGHLiN, G. F. Notes on the Weathering of Natural Building Stones. Proc. Am.

Soc. Test. Mat., vol. 31, pt. II, 1931, pp. 759-767.
Marsh, J. E. Suggestions for the Prevention of the Decay of Building Stone.

Basil Blackwell, Oxford, England, 1923, 20 pp.
Merrill, G. P. Stones for Building and Decoration. 3d ed., John Wiley & Sons,

Inc., New York, 1910, 551 pp.
Rocks, Rock- Weathering, and Soils. The Macmillan Company, New York,

1921, 400 pp.
Schaffer, R. J. The Weathering of Natural Building Stones. Dept. of Sci. and

Indust. Research; Building Research Special Rept. 18, London, 1932, 149 pp.

(Contains an extensive bibliography.)
Warnes, a. R. Building Stones, Their Properties, Decay, and Preservation.

Ernest Benn, Ltd., London, 1926, 269 pp.

PART III
CRUSHED AND BROKEN STONE

CHAPTER XVI

GENERAL FEATURES OF THE CRUSHED -STONE
INDUSTRIES

History. — Dimension stone has been in use for many centuries, but
employing stone in fragmentary form, except in very small quantities,
is a comparatively recent development. The convict chain gang, break-
ing rocks with hand sledges to improve the surface of highways, was a
forerunner of the extensive crushed-stone industry, which grew with
accelerated speed after the invention of portland cement. The manu-
facture of cement has attained enormous proportions, with a production
of about 175,000,000 barrels a year. Nearly all of it is used in concrete,
which requires gravel, slag, or crushed stone as aggregate. Furthermore,
the manufacture of cement itself consumes a very large tonnage of lime-
stone. Within the past 50 years the production of crushed stone grew
from small, insignificant stature to a volume of approximately 188,000,000
tons a year in 1929. The quarrying and preparation of this vast tonnage
employ several thousand men and require an enormous investment in
equipment, because the processes are largely mechanical.

Types and Quantities Employed. — The chief varieties of rock used as
crushed stone are limestone (including marble), sandstone (including
quartzite), granite, basalt and related rock (trap), and various other
rocks generally grouped as miscellaneous. The tonnage of these various
types produced in crushed and broken form is shown in the following table
compiled from United States Bureau of Mines figures:

Crushed and Broken Stone Produced in the United States, 1929-1930 and
1936-1937, IN Short Tons, by Varieties

Kind

1929

1930

1936

1937

Limestone (including marble) . . .
Basalt (trap rock)

151,365,350

14,820,140

9,115,700

5,134,600

8,179,870

134,621,120

14,492,800

8,717,170

3,950,240

8,525,690

123,148,990

13,977,030

14,775,300

6,091,840

7,764,740

131,772,990
13,556,360

Granite

8,514,500

Sandstone (including quartzite)
Miscellaneous

4,841,030
10,374,130

Total

188,615,660

170,307,020

165,757,900

169,059,010

The quantities of limestone given in this table include that ordinarily
designated "crushed stone," together with that consumed in the manu-
facture of cement and lime and for miscellaneous uses.

371

372

THE STONE INDUSTRIES

The chart (figure 66) shows graphically the rapid and enormous
growth of the crushed-stone industry from 1907 to 1932. However,

l-J\J

inn

Value perTon^^^

'•-.

—

__^,

•_2:

■JL

Lid

■zi

inn

—

/7e

yet

/es

t
1

Value,clollars~

' j

J
1

■

Production, shorf ions

o 50

[

2 45

1 y

s.^

'•V

—

*^1

Fig. 66.

1908 1910 1912 1914 1916 1918 1920 1922 1924 1926 1928 1930 1932
Years

-Quantity and value of crushed stone sold in the United States, 1907-1932.

this graph does not correspond with figures of production as given in
the preceding table, because it is based on production of concrete
aggregate, road stone, and railroad ballast only. As may be observed

GENERAL FEATURES OF THE CRUSHED-STONE INDUSTRIES 373

in the chart, the production curve for the entire country rises to a sharp
peak in 1913, recedes shghtly during the early years of the World War,
and then drops precipitously in 1917 and 1918. After 1918 production
increased steadily each year at a fairly uniform rate until 1927, the peak
being almost double that of 1913, the high year up to 1918. The
extensive road-building programs in many States probably constitute the
largest single factor influencing this sharp increase. A second pronounced
drop in the curve began in 1928 preceding by a year the general business
depression and market breaks that began late in 1929.

Crushed Stone and Dimension Stone Contrasted. — The dimension-
stone and crushed-stone industries have little in common, except that
both employ native rock as raw material. For quarrying dimension stone
explosives are used very sparingly, as the integrity of blocks must be
maintained. Cuts are made with channeling machines or wire saws, or
rock masses are separated by wedging, whereas in quarrying crushed stone
heavy charges of dynamite are used for fragmentation. Similarly, in all
subsequent steps of preparation for market methods and equipment are
sharply contrasted. The producer of dimension stone uses saws, planers,
Carborundum machines, rubbing beds, and polishers; the producer of
crushed stone employs churn drills, power shovels, crushers, screens,
elevators, and belt conveyors. Dimension stone is sold chiefly by the
cubic foot, and much of it commands a price high enough to give it a
nationwide market. Crushed stone is sold by the ton and is so low-priced
that it will not bear heavy transportation expense. As raw materials for
crushing are available in many places, quarries are numerous and are
scattered throughout the country in thousands of communities, whereas
the dimension-stone industries are centralized in a much smaller number
of localities.

Uses of Crushed Stone. — The chief uses of crushed stone are for road
building, as concrete aggregate, and as railroad ballast. In highway
construction it is used as concrete aggregate, for road base, in waterbound
macadam, and in various other ways. Concrete, now used extensively in
all building construction, consumes large quantities of crushed stone or
similar aggregate. Millions of tons are used to ballast railway lines
throughout the country. In one or more of these three major appli-
cations crushed stone finds a place in the experience of virtually every
citizen. Numerous other uses are discussed in following chapters.

Competition. — Stone suitable for crushing is obtainable in many
places; in most regions it is practically impossible for an operator to
monopolize available deposits. Furthermore, he must face competition
from natural gravel, which is sold in immense quantities, and, in territory
near smelters, from crushed and granulated slag. Success in meeting
competition from other stone producers depends somewhat on relative
conditions, such as depth of overburden or ease of transportation. The

374 THE STONE INDUSTRIES

operator who controls the most favorably situated part of a deposit
enjoys an economic advantage. Modern trends involve more complete
mechanization of plants and the consolidation of small organizations into
fewer large ones. The former reduces production costs, and the latter
absorbs competitors and reduces administration expense through more
centralized control. With ever-increasing rigidity of specifications the
quality of the product is also an important factor in competition, because
a superior product may compete successfully with a lower-priced, inferior
commodity.

Markets. Local Markets. — Crushed stone commands a low price;
therefore, as haulage charges are relatively high, profitable operation
depends largely on the extent of local markets. The producer of crushed-
stone is most interested in steady market requirements to supply every-
day needs of builders, contractors. State highway departments, and other
users. As such requirements have a definite relation to population, an
increasing demand may be expected in growing communities. Large
crushing plants supplying wide markets usually suffer less from variation
in local demands than smaller plants with limited market areas. A new
highway, dam, or bridge may require large quantities of crushed stone
for a time, but the demand is reduced greatly when the project is com-
pleted. The wise producer gages his plant capacity by the normal
demand but is prepared to profit by any extraordinary market
opportunities.

The demand for crushed stone varies greatly in different communities,
even though they are similar in population and in per capita wealth.
Demand is influenced by prevailing types of architecture and by avail-
ability and cost of materials, such as sand and cement used with crushed
stone, and by competition of concrete with brick, stone, or other products.

Distant Markets. — Although crushed stone is a low-priced product
with a relatively limited market range, during recent years the market
area of many plants has been extended greatly. Production costs have
been reduced by the use of more efficient equipment and methods and by
consolidation into larger units. Transportation facilities have been
improved also. Year by year hard-surfaced highways are extended, and
trucks hauling heavy loads at 35 to 50 miles an hour are multiplying.
Increasing use of water transportation, notably on the Great Lakes, is an
important trend. Plants with large-tonnage production, efficient equip-
ment, economical management, and low-cost transportation may ship
their products long distances and compete successfully with local stone in
far-distant markets.

Transportation. — The haulage charge usually is a large part of the
delivered price of crushed stone. Producers strive to maintain low freight
rates, because even small increases are serious handicaps in a competitive

GENERAL FEATURES OF THE CRUSHED-STONE INDUSTRIES 375

field and tend to reduce market areas. Automobile trucks, water carriers,
and railroads are the three principal means of transportation. The first
and second have made notable progress during recent years, consequently
rail carriers have suffered some recession in their share of a rapidly
increasing business.

Prices. — Market prices for crushed stone differ materially from metal
prices. Copper, for example, is quoted at a certain price per pound
which is virtually constant throughout the entire country and even in
foreign markets. The price per pound is relatively so high that the cost
of transportation is too small to influence it appreciably. On the
other hand, transportation expense influences the price of crushed stone
greatly. Prices are therefore subject to local conditions of production
cost, and competition. Usually the market columns contain about 50
quotations representing the chief market centers. Prices may vary
widely even within restricted areas; therefore, the determination of
selling prices is an individual problem for each producer. As may be
noted from the curve (fig. 66), the average price of crushed stone at the
quarry is generally a little more than $1 a ton.

Royalties. — Many crushed-stone producers operate in deposits they
do not own. In such instances it is customary to pay the owner of the
property a royalty of so much per ton of crushed stone sold. Data on
which royalties are based have been discussed in chapter V. Royalties
for crushed stone are 1 to 10 cents a ton depending on local conditions.
The lower figures usually prevail where production is large, but other
factors, such as sales value per ton or production cost, may influence the
amount.

Capital Required. — A prospective operator desires to know how much
capital he must have to establish a crushed-stone industry. Investment
of capital is subject to considerable variation because of the number and
variety of elements that enter into it. Just as the operating cost in no
two quarries is the same, so the capital required to establish two equally
efficient crushing plants may vary widely. It is interesting, however,
to know even approximately the average investment for a stone quarry
and crushing plant.

The most reasonable basis for expressing investment is the capital
required per ton of annual production. Thus, if the plant costs $1,000,-
000 and the production is 1,000,000 tons a year, the investment is $1 an
annual ton. Certain variables enter into the problem at this point, for
annual production may refer to actual output or to plant capacity, and
the production capacity of a plant depends on efficiency of management
as well as on equipment. Capital investment, expressed in terms of
actual tons produced over a series of years, probably is of more value
to the industry than a figure based on rated plant capacity.

376 THE STONE INDUSTRIES

A detailed study of 64 crushed-stone plants in the United States shows,
according to a recent report,^^ an average capital investment of $1.25
an annual ton of average production over a two-year period. This figure
is based on depleted values representing actual replacement values of the
properties. Therefore, a prospective producer who is just beginning
operation, putting up new buildings, and buying new equipment must
estimate his initial investment at a somewhat higher rate than the figures
given above. Land and mineral constitute about 15 per cent of the
total capital requirement, plant and equipment about 85 per cent.

^^ Bowles, Oliver, Economics of Crushed-stone Production. Economic Paper 12,
U. S. Bur. of Mines, 1931, p. 53.

CHAPTER XVII

CRUSHED AND BROKEN LIMESTONE
TYPES OF STONE INCLUDED

For many uses the chemical composition of crushed stone has Uttle
significance. On this account the general term "Umestone," as used in
the crushed-stone industry, includes both pure and impure limestone,
high-calcium limestone, magnesian limestone, dolomite, and crystalline
forms that usually are classed as marbles. However a comparatively
small amount of crushed marble obtained as a by-product of the block-
marble industry is not included in the production figures given in a follow-
ing paragraph.

EXTENT OF INDUSTRY

Limestone is the most widely used of all rocks and is essential in a
greater number of industries than any other metallic or nonmetallic
mineral substances. It might be claimed that iron and steel are employed
more widely, but those industries as constituted at present could not
exist without large quantities of limestone; thus, it is indirectly essential
to all the uses of iron and steel. Other rocks, such as granite, trap, and
sandstone, are also used as crushed stone, but they form a smaller part
of the industry; limestone accounted for more than 80 per cent of the
total amount in 1929. The quantity produced from 1926 to 1937 is
shown in the following table:

Crushed and Broken Limestone* Sold or Used by Producers in the United

States, 1926-1937

Year

Quantity,
short tons

Year

Quantity,
short tons

1926
1927
1928
1929
1930
1931

141,321,640
151,163,700
149,025,390
151,135,720
134,425,430
102,789,680

1932
1933
1934
1935
1936
1937

69,672,740
65,938,430
81,446,000
82,688,160
123,081,030
131,660,690

* Includes stone used for cement and lime manufacture.

USES OF CRUSHED AND BROKEN LIMESTONE

The uses of limestone are more numerous and diversified than those of
other stones, because it has physical properties that adapt it to practically
all the uses for which any form of crushed stone may be employed ; and in
addition, it has active chemical properties that make it not only useful

377

378

THE STONE INDUSTRIES

but absolutely essential to a great many industries. The quantity of
crushed or broken limestone applied to various uses is indicated in the
following table for a typical year, adapted from United States Bureau
of Mines figures.

Crushed and Broken Limestone Sold or Used in the United States in 1930,

BY Uses

Short
Uses tons

Riprap 2,918,110

Crushed stone 56 , 775 ,

Fluxing stone 17,021

Sugar factories 414,

Glass factories 224 ,

Paper mills 248,

Agriculture 2 , 542 ,

AlkaU works 4,436,

Asphalt filler 430

Calcium carbide works 364

Carbonic acid works 2

Coal-mine dusting 47

Fertilizer filler 12

Filter beds 30

Magnesia works (dolomite) Ill

Mineral food 30

Mineral (rock) wool 64

Poultry grit 45

Refractory stone (dolomite) 453

Road base 139

Roofing gravel 1

Stucco, terrazzo, and artificial stone 59

Whiting substitute 119

Portland cement (including "cement rock") 40,500

Natural cement ("cement rock ") 341

Lime 6 , 780

Other uses* 310

060
350
340
180
790
100
160
290
750
290
750
240
860
740
350
850
920
350
030
740
570
350
000
000
000
260

134,425,430

* Includes stone for ammonia, baking powder, lime burners, nitrates, phosphates, powder, purifica-
tion of copper, reduction of aluminum ore, soap, sulphuric acid, and uses not specified.

For concrete aggregate, road stone, and certain other applications
such physical properties as hardness, strength, and porosity have primary
importance. For other uses, such as lime manufacture and furnace flux,
chemical composition is much more important than physical character.
The uses described in following pages are grouped in these two major
classes.

Uses for Which Physical Properties Are Most Important. Concrete
Aggregate. — Within the past twenty-five years concrete has become a
construction material comparable in importance with structural steel.
The cement output in the United States has reached the enormous volume

CRUSHED AND BROKEN LIMESTONE 379

of about 175,000,000 barrels annually; and nearly all of it is used in
concrete, principally for highway construction and in the building
trades. The vast tonnage of aggregate required consists chiefly of
limestone, although other kinds of crushed stone as well as gravel and
slag are used quite extensively. For such use limestone should be strong,
sound (free from incipient cracks or seams), and of low porosity. Much
work has been done in the development of tests by means of which the
quality of aggregate may be judged. A complete list of tests and
specifications has recently been published." Requirements of users
differ widely, but geneially aggregate should consist of clean, hard, strong,
durable, uncoated fragments free from injurious amounts of soft, friable,
thin, elongated or laminated pieces.

Alkalies and organic matter usually are regarded as undesirable.
Soluble sulphides are objectionable, as they oxidize and give sulphuric
acid, which attacks any calcareous aggregate or lime present in the
cement, forming gypsum. Gypsum expands greatly during crystalliza-
tion, thus disrupting the concrete. The chief qualities to be determined
are strength, soundness, and resistance to abrasion, although porosity,
hardness, and other properties may be considered. Standard tests
include the Deval abrasion test, the Dorry hardness test, the Page impact
test, and the ordinary methods of crushing-strength tests. Soundness is
important because disintegration of some concretes has been traced to
incipient seams or to other physical defects in the aggregate. Various
tests have been devised to determine the soundness of coarse aggregates.
The more important of them are: (1) freezing and thawing tests; (2) the
sodium sulphate test; (3) the sodium chloride test; and (4) the alkali test.
Each method involves the freezing or crystallization of a substance in the
pores or cracks, resulting in heavy interior strain.

Requirements may vary considerably, depending on whether the
stone is to be used for concrete aggregate, with bituminous material, or in
some other way. State highway officials are recognizing the need for
more uniform specifications, and this need has found expression recently
in a set of tentative standards^^ covering stone to be used in the construc-
tion of both macadam and concrete highways.

Much study is being devoted to the proper sizing of aggregates and the
proportioning of the various sizes necessary for maximum strength and
durability with a minimum of cement. The present tendency is toward
a combination of sizes that will give the lowest percentage of voids; in
other words, the aggregate mixture should approach a condition of maxi-

" Ingels, C. W., National Directory of Commodity Specifications. U. S. Bur.
of Standards Misc. Pub. 130, 1932, pp. 169-174.

^* Tentative Standard Specifications for Highway Materials of the American
Association of State Highway Officials. Washington, 1929, 56 pp. (see also revision
of 1931).

380 THE STONE INDUSTRIES

mum density. This condition is best attained when two diverse sizes
are used.

Road Stone. — Various sizes of stone are used for bituminous and
macadam roads. Material under }i inch, classed as fine screenings, is
used principally for waterbound macadam. Coarser screenings up to
}'2 inch are employed as fine aggregate for bituminous concrete. Sizes
between J^^ inch and ^4 inch classed as dustless screenings or chips are
utilized for surface treatment of bituminous roads. Sizes between
^■4 inch and 1^^ inch are used as coarse chips for bituminous macadam.
Sizes ranging from 1^4 to 2}^ inches are suitable for the wearing course
of waterbound or bituminous macadam. Fragments between 23^^ and
3^^ inches are used for base courses of highways.

The requisite qualities of road stone are similar to those of aggregate,
except that resistance to abrasion has first importance, for the stone
should be tough and hard enough to withstand the pounding and grinding
of traffic. For this reason, road stone may be subjected to an impact
test to determine its wearing qualities. Thousands of tests have been
made by the Department of Agriculture, Washington, D. C, to determine
the physical properties of road stone, and a tabulation of results has been
published. ^^

Road stone should break into sharply angular, chunky fragments.
Such fragments, if properly graded by size, will compact solidly into the
surface of the road and on account of the strong interlocking of angular
pieces will offer maximum resistance to disruption by traffic. Soft stone
breaks up rapidly under traffic; and laminated stone, even if fairly hard,
will break into flat or elongated pieces which will not compact solidly.
Rough-faced fragments bind and wear better than those with smooth
surfaces. A low ratio of absorption is desirable; otherwise, water may
penetrate and soften the structure of the road. Various standard
methods of tests, sampling, and mechanical analysis are given in American
Society for Testing Materials Standards, part 2, 1927.

Railroad Ballast. — Many thousand tons of limestone are used by
railroad companies to maintain or improve the condition of roadbeds.
The American Railway Engineering Association has fixed 9^ inch as the
minimum and 2}^ inches as the maximum for ballast sizes. The general
requirements are similar to those for aggregate and road stone. Some
railroad companies operate quarries of their own; others purchase the
necessary stone from quarries along their lines.

Riprap. — Riprap consists of heavy irregular rock fragments used
chiefly for river and harbor work, such as spillways at dams, shore protec-
tion, docks, and other similar construction that must resist the force of
waves, tides, or strong currents. It is also used to fill in roadways or

59 Woolf, D. O., The Results of Physical Tests of Road-Building Rock. U. S.
Dept. of Agriculture Misc. Pub. 76, 1930, 148 pp.

CRUSHED AND BROKEN LIMESTONE 381

low places in yards. Any type of dense, sound limestone may be used
in this way. There are no general specifications covering it, but require-
ments for individual jobs may be enumerated. Riprap is a very low-
priced product and usually is obtained from quarries situated along rivers
or available to cheap coastwise transportation.

Dusting Coal Mines. — Dust explosions in coal mines are dreaded
more than any other accidents by miners and operators. A coal-dust
explosion is an extremely rapid burning or combustion of coal particles.
The air shock travels ahead of the flame, stirs up the dust, mixes it with
the air, and thus enables the flame to extend the explosion. In a dusty
mine therefore an explosive wave may travel through miles of entries,
shafts, and headings and cause great loss of life.

When mixed with coal dust, fine incombustible dusts make ignition
of coal particles more difficult. If the inert dust equals the coal dust in
amount there is practically no danger of explosion from ordinary causes,
such as blow-out shots, because it practically dilutes mixtures of coal,
inert dust, and oxygen to a point where continued combustion becomes
difficult or impossible.

Any incombustible powder may be used for dusting, but some
materials are preferred above others. Dark dusts are not desirable, as
they can not be readily distinguished from coal dust. On the other hand,
white dust contrasts distinctly, and the proportion of inert material
present is more readily estimated. A high silica content is undesirable
because silica dust is regarded as injurious to the lungs of miners.
Therefore, the best dust is white, incombustible, and low in silica.

Limestone fulfills the foregoing conditions admirably. It is essen-
tially carbonate of lime, a compound that is not considered injurious to
the lungs. It can be ground to a white or light-gray powder ,^is abundant,
and usually may be procured at low cost. The advantage of dusting
coal mines as a safety measure has been urged by the Bureau of Mines,
and the satisfactory service rendered by limestone has led to its wide
use during recent years. Several hundred bituminous-coal mines now
employ the method, and for this purpose approximately 60,000 to
70,000 tons of pulverized limestone are used annually.

Producers of limestone welcome dusting of coal mines as an outlet
for waste material, because many of them are handicapped by accumula-
tions of fines which are difficult to sell. As the material commands a low
price per ton, quarries near coal fields have an advantage in this market.

A low silica content is desirable, but the screen-size specifications are
not exacting. Those approved by the United States Bureau of Mines
require that 100 per cent shall pass through a 20-mesh screen and 50 per
cent through a 200-mesh screen.

Chalk, Whiting, and Whiting Substitutes, general features. —
Chalk is defined as a noncrystalline, soft, friable, fine-grained, light-

382 THE STONE INDUSTRIES

colored type of limestone consisting essentially of calcareous shells of
minute organisms known as "foraminifera." The distinguishing physical
characteristics of true chalk never have been fully defined; probably its
noncrystalline and colloidal properties are most important. Whiting
is a pulverized, purified, carefully sized chalk. Whiting substitutes
include finely ground limestone or dolomite, ground marble (marble
flour), white marl, and chemically precipitated calcium carbonate.

Very little true chalk has been produced in the United States;
domestic requirements are supplied from deposits in England, France,
Belgium, and Denmark. A few years ago chalk was obtained from some
American deposits, but very little, if any, of the present domestic pro-
duction of pulverized calcium carbonate can be classed as true chalk.

Chalks of Cretaceous age occur in many places, chiefly in the Mid-
Central and Southern States. Most of them contain high percentages of
impurities, such as clay and sand, but several occurrences of reasonable
purity have been noted. According to available records, the only produc-
tion of true chalk of any consequence has been confined to Alabama. In
other States, notably in Arkansas, Iowa, Kansas, Mississippi, Nebraska,
South Dakota, and Texas, further prospecting and testing may develop
valuable supplies. The Cretaceous occurrences of Colorado, Louisiana,
Montana, and North Dakota are unpromising as sources of chalk.

Whiting substitutes, mostly in the form of finely pulverized limestone,
are produced in many localities. They are used chiefly as rubber filler
and less extensively in paint and putty. Generally, limestone flour that
vrill successfully meet the requirements of fillers of a type like whiting or
china clay should be ground to a powder of approximately 300-mesh
grain size. Chemical purity, though not essential, is desirable, as snow-
white powder is most in demand. Some companies manufacture a very
pure calcium carbonate by a process of precipitation from a milk-of-lime
suspension. This chemically controlled product is used chiefly as a
dentifrice. Finely divided calcium carbonate obtained as a by-product
of caustic soda manufactured at paper mills is used chiefly as rubber
filler. In seeking a market for his product the manufacturer of whiting
substitutes should be familiar with the many and varied uses of whiting,
the more important of which are given in the following paragraph.

USES OF WHITING. — An important use is for calcimine and cold-water
paints which contain about 80 per cent pure white whiting. True whiting
is preferred because ground limestone and marble have poorer covering
effects. The manufacture of putty, a mixture of 85 per cent whiting
or whiting substitute with 15 per cent linseed oil, also consumes a large
amount. True whiting usually is preferred for this purpose also. A
third important use is as a ceramic raw material to supply the calcium
oxide component of glazes and enamels or as a fluxing agent in body
mixtures. Whiting is employed as a filler in numerous products, such as

CRUSHED AND BROKEN LIMESTONE 383

rubber, paint, paper, oilcloth, window shades, and linoleum. Other
products in which it is an important constituent include white ink,
dressing for white shoes, picture-frame moldings, dolls, wire insulation,
dyes, toothpaste, and fireworks. It is used for facing molds and cores
in brass casting and as a mild abrasive for polishing metals.

PREPARATION OF MATERIALS.— Crude chalk imported from Europe is
ground to a fine powder, purified, and classified by a process of water
settlement, the finest and highest-grade materials being those that
remain longest in suspension. The more modern mills employ bowl
classifiers, thickeners, and filters.

Limestone and marble are pulverized and graded by two processes —
the wet method and the dry method, but for some uses a wet-ground
product is preferred. Wet grinding usually is done in pebble mills, and
classification into sizes is accomplished by water settlement. Moisture
commonly is driven off by means of drum driers. For dry-process
grinding the crushed stone usually is passed through a rotary drier and
then ground by any one of a variety of processes. Rolls or impact mills
of the swinging-hammer type usually do the coarser grinding, and impact
pulverizers or pebble mills the final grinding. Sometimes grading by size
is done with air separators supplemented by vibrating screens. Several
mills are equipped for both wet and dry processes.

Calcium carbonate obtained as a chemical precipitate is manufactured
from calcium oxide (quicklime) and carbon dioxide gas. The lime is
hydrated and enough water added to make a milk-of-lime suspension.
The carbon dioxide gas, usually obtained by burning coke, is blown in at
the bottom of the tank containing the lime suspension and, combining
chemically with the lime, forms a finely divided calcium carbonate, which
is prepared for market by filtering and drying.

Miscellaneous Uses, sewage filter beds. — Growth of towns and
cities demands increasing use of filtering materials for sewage purposes if
public health is to be preserved. The function of filter stone is to supply
a lodging place for bacteria which accumulate on the surface of the rock
fragments and by their life processes effect purification of the sewage.
Crushed limestone is satisfactory for this purpose, and large quantities
are so used. The chief qualifications as described by Lamar^^ are as
follows: Certain impurities, notably pyrite, marcasite, and clay, are to be
avoided. If fine-grained and evenly distributed, siliceous impurities are
not objectionable. Either high-calcium or dolomitic limestone may be
used. Absorption should be low and pore space evenly distributed.
The stone should be of uniform solubility, firmly cemented, and strong,
and the fragments should have surfaces sufficiently rough to provide
anchorage for bacteria. Fines and dirt should be screened out.

*" Lamar, J. E., Limestone for Sewage Filter Beds. Illinois State Geol. Survey,
Kept, of Investigations 12, 1927, 21 pp.

384 THE STONE INDUSTRIES

STUCCO AND TERRAZzo. — Dense, compact limestones of attractive
colors may be crushed into small fragments for terrazzo floors. Similar
material reasonably impervious to moisture finds some use in stucco and
pebbledash work.

POULTRY GRIT. — Limestoue crushed to granules and screened to
uniform sizes is sold in considerable quantities as poultry grit. The term
is a general one, for the products may be graded by sizes into turkey grit,
chicken grit, pigeon grit, and bird grit. Producers reported to the
United States Bureau of Mines a total of 34,600 tons, valued at S221,610,
in 1929. It is probable that the figures given are low, as many operators
fail to report small sales of by-products. Very few plants operate for the
production of poultry grit only; it is obtained chiefly as a by-product at
crushing plants. The chemical composition of the stone is of minor
importance. Although pure, crystalline calcite may have some advantage
in appearance, almost any type of limestone, pure or impure, may be
used. In fact, one company reports a "mica crystal grit," from which
one would infer that it consists of siliceous material.

It is claimed that oyster shells have exceptional virtues as constituents
of poultry food, and increasing quantities are so used. Production for
this use increased from a value less than .$100,000 in 1918 to approximately
$2,000,000 in 1931; and exports, chiefly to the United Kingdom, were
valued at more than a half million dollars in the latter year. As this
material is derived from shell banks it is not included in limestone
statistics.

CONCRETE BLOCK FACING. — Concrete blocks made to resemble cut
stone or rough stone are used widely. The resemblance to stone is
increased by embedding limestone chips on the exposed surface. A small
tonnage of limestone is sold for this use.

CONCRETE BLOCK AGGREGATE. — Cement, sand, and fine aggregate are
mixed in various proportions in the manufacture of concrete blocks.
Limestone screenings are well-adapted for use as aggregate in both
concrete blocks and concrete brick.

ROAD SURFACING. — Limestone screenings are used widely for surfacing
waterbound macadam roads. Fine screenings are employed also as
coatings on the surface of new asphaltic pavements or in resurfacing and
patching old pavements.

YARD AND PLAYGROUND SURFACING. — Screenings without a binder are
used for station platforms; they afford good drainage, while footsteps of
travelers and w^heels of baggage trucks pack them down to a firm compact
surface. Screenings are also used to surface walkways, playgrounds,
school yards, and tennis courts. Fines usually are included to serve as a
binder.

LIMESTONE SAND. — Limestoue crushed to the size of sand grains is
used as a substitute for silica sand in mortar, wall plaster, and concrete.

CRUSHED AND BROKEN LIMESTONE 385

When carefully graded and washed, limestone sand has been employed
very successfully for this purpose, but attempts to use unclassified screen-
ings have caused some reaction against it. Mortar tests reported by.
Kriege*'^ show strengths considerably in excess of those obtained with
standard silica sands. Quite a large tonnage of limestone sand has been
used in concrete highway construction in the Middle West.

ASPHALT FILLER. — ^Limestone dust, approximately 80 per cent of which
will pass a 200-mesh screen, is the filler used most generally in road
asphalt-surface mixtures, although slate flour, portland cement, and
hydrated lime are employed to some extent. Many thousand tons are
used in the larger cities. The preparation of asphalt filler is an appreci-
able part of the business of some limestone-quarrying companies, but for
the most part it is regarded as a by-product activity for the utilization of
fine materials that would otherwise be wasted. Annual production in
the United States is about 400,000 tons, and the average price at the
grinding mill is $3 to $3.50 a ton. Asphalt fillers are described in some
detail by Emery. ^^

ROOFING GRAVEL. — Screened limestone chips ranging in quantity from
5,000 to 8,000 tons a year are sold as roofing gravel for use with tar on flat
roofs. The average price is $2 to $2.50 a ton at point of production.

Uses for Which Chemical Properties Are Most Important. Chemical
Purity Not Always Essential. — For all the uses enumerated in this
section the chemical composition of limestone is more important than
the physical properties; for some chemical purity is demanded. Thus,
stone for the manufacture of lime ordinarily should contain not more than
1 or 2 per cent siliceous impurities. For certain other uses the importance
of chemical composition is not to be interpreted as a demand for chemical
purity; for example, limestone for cement manufacture, although it may
not be pure, must have a composition that permits proper balance between
the chemical constituents. Ideal cement rock contains about 20 per cent
clay. For certain uses the magnesium content should be high.

Manufacture of Cement. — Limestone is the chief raw material of
Portland cement; in average practice about four parts of high-grade
limestone are mixed with one part of clay or shale. Briefly, cement
manufacture consists of calcining in a rotary kiln finely pulverized raw
materials to a temperature of incipient fusion and grinding the resulting
chnker to a fine powder. About 3 per cent gypsum, which serves as a
retarder, is added to the clinker before grinding. The process of cement
manufacture from quarry to pack house is shown diagrammatically in
figure 67.

^1 Kriege, Herbert F., Washed Limestone Sand. Pit and Quarry, vol. 17, no. 11,
Feb. 27, 1929, pp. 64-66.

^2 Emery, A. H., Mineral Fillers for Sheet-asphalt Paving Mixtures. Am. Inst.
Min. and Met. Eng., Contrib. 17, 1933, 28 pp.

386

THE STONE INDUSTRIES

ft?

CRUSHED AND BROKEN LIMESTONE 387

Common massive limestone is used most generally as a raw material,
but other varieties, including marble, chalk, marl, and cement rock, are
employed in some places. In Virginia, Texas, and California oyster
shells are used.

Cement rock is simply an argillaceous limestone, which in some
localities contains enough clay as it occurs in nature to adapt it for the
manufacture of cement, though sometimes it may be necessary to adjust
the composition by adding small quantities of high-calcium limestone or
clay. The Lehigh Valley district of Pennsylvania is an important
locality for the use of cement rock.

As Portland cement consists essentially of 60 to 70 per cent calcium
oxide, 20 to 25 per cent silica, and 5 to 12 per cent alumina and iron
oxides, evidently pure limestone is not required. Considerable per-
centages of silica and alumina are permissible, but to simplify the problem
of proportioning the raw materials, constancy in chemical composition is
desired. Although the requirements of limestone for cement manufacture
are not exacting the following limitations should be observed: (1) The
rock should be free of concretions of iron minerals, should contain little
free silica in the form of chert, flint, or quartz veins, and should be free
of silicate minerals, such as tremolite and diopside; (2) the silica and
alumina contents should be low enough and in such ratio that they will
not interfere with the desired silica-alumina ratio in the finished product ;
(3) the rock should be low enough in magnesium so that the finished
product will contain not more than 5 per cent magnesia (MgO) ; (4) the
content of iron should be sufficiently low that the ferric oxide content of
the finished cement will not exceed 4 per cent; (5) the sulphur content
should be low.

The manufacture of cement is a very important use for limestone, as
about 45,000,000 tons are consumed for this purpose every year. Lime-
stones suitable for cement manufacture occur in many localities, con-
sequently the industry is widely distributed, between 150 and 160 plants
operating in 33 States. The distribution of raw materials for cement
manufacture is given in some detail in a report by Eckel^' and others.

In choosing a location for a cement plant, however, an adequate
supply of suitable raw materials is not the only consideration. Other
factors on which success depends are markets, both local and distant,
transportation facilities, and fuel supplies.

Manufacture of Lime. — ^Lime consists of either calcium oxide or the
combined oxides of calcium and magnesium. In brief, the process of
lime manufacture consists in heating limestone to a temperature at which
the carbon dioxide is driven off. This process for a high-calcium lime-
stone may be expressed by the chemical equation CaCOs + heat =

^' See bibliography at end of chapter.

388 THE STONE INDUSTRIES

CaO + CO2. In converting limestone into lime there is great loss in
weight — 100 pounds of pure stone yielding only 56 pounds of lime.

Most lime plants consist of shaft kilns into which 4- to 12-inch
limestone fragments are dumped. Two or more fire boxes or grates are
situated near the bottom of the shaft, and heat therefrom calcines the
stone. The finished product sinks below the grate level and is removed
from the bottom of the shaft. Lime also is manufactured in rotary
kilns similar to those used in making cement.

Stone suitable for lime manufacture must conform to rather rigid
physical and chemical requirements. Both high-calcium and high-
magnesian limestones or dolomites are employed. High-calcium limes
are used chiefly for mortars and for chemical purposes, while highly
plastic magnesian limes are employed principally for finishing plasters.
Magnesium therefore is not regarded as an impurity in limestone for
lime manufacture. The most common impurities are silica, alumina,
iron, and sulphur. Most lime now sold is manufactured from stone of
exceptional purity, total carbonates ranging from 97 to 99 per cent of the
rock mass. The demand for a high degree of purity in the stone is due
largely to the fact that practically all impurities in each 100 pounds of
stone remain in the approximately 56 pounds of lime that results from
calcination. Therefore, lime manufactured from stone containing 2
per cent impurity will contain nearly 4 per cent of undesirable constituents.

The stone should be sound physically and so firmly consohdated that
it may be quarried with a limited production of fine materials which are
excluded from shaft kilns and are commonly wasted. Porous, friable
limestones not only produce abundant fines but break down during
calcination and so retard the draft that they can not be used satisfactorily
in shaft kilns.

Normally, between 8,500,000 and 9,000,000 tons of limestone are used
annually in the United States for manufacture of lime. A total of 381
active producers reported to the United States Bureau of Mines in 1929.
The industry is widely distributed throughout the country; plants
are operating in 39 States. Lime enters three important fields of utiliza-
tion; in 1929, 53.7 per cent of the total production was used in the chemical
industries, 38.4 per cent for mortar and plaster in the building industries,
and 7.9 per cent for liming land. In the chemical industries it has so
many diversified uses that it has been designated "the king of all the
bases." It is claimed that lime is essential to the conduct of more than
120 manufacturing industries, but as this book deals primarily with
stone in its raw state these uses are not considered.

Rockland, Me., is the most northeastern point in the country where
lime is now produced. A belt extending from the Canadian border
through western Vermont, Massachusetts, Connecticut, and eastern
New York contains both dolomitic and high-calcium limestones. Most

CRUSHED AND BROKEN LIMESTONE

389

of the lime produced in New York is from a belt extending across the
center of the State. Both high-calcium and dolomitic limestones are
widely distributed throughout the southern half of Pennsylvania, and
the heavy output of many large plants throughout that district has placed
the State second in rank as a producer of lime. From eastern Penn-
sylvania a limestone belt extends southward, supplying raw materials
for important lime industries in Maryland, Virginia, West Virginia, east
Tennessee, Georgia, and Alabama.

All of the Central States are well supplied with suitable limestone.
A district extending 20 to 30 miles from Toledo, Ohio, is the most pro-
ductive area in the country, and most of the plants utilize an almost pure

Fig. 68. — A typical Ohio lime plant and quarry with supplementary crushing and screening

plant shown at left.

dolomite. Eastern Wisconsin, southern Minnesota, Illinois, Indiana,
and Missouri are well provided with raw materials for numerous plants.

In the Rocky Mountain and Pacific Coast States the reserves of both
high-calcium and dolomitic limestones are adequate, but commercial
development is limited by the somewhat restricted demands for lime.
Present activity is confined chiefly to areas near centers of population and
lime-consuming industries, notably Denver, Salt Lake City, El Paso, Los
Angeles, San Francisco, Seattle, and Butte. A large Ohio lime plant is
shown in figure 68.

Furnace Flux. — Iron ores contain silica and alumina as impurities,
and in the smelting process the addition of a basic flux, such as limestone,
is necessary to remove the undesirable elements. The process of removal
is based on the fact that silica and alumina have a stronger affinity for
lime and magnesia than for iron; consequently, double silicates of lime
and alumina, or magnesia and alumina, are fused into liquid slag which

390 THE STONE INDUSTRIES

floats on the molten iron. Sulphur in the ore, together with sulphur and
ash from the coke, is also removed by slag.

As the chief purpose of flux is the removal of silica and alumina from
ores it is evident that limestone employed for this purpose should be low
in these compounds. If an impure stone is used, part of the carbonate
content is absorbed in fluxing off foreign elements in the stone, which
reduces the amount available for removing impurities of the ore. "Avail-
able carbonate" is a term applied to the percentage of calcium and
magnesium carbonates left for fluxing the ore after a sufficient percentage
has been deducted to neutralize impurities in the stone itself. In average
blast-furnace slag the ratio of silica plus alumina to lime plus magnesia
is about 1 to 1; in other words, for every pound of silica and alumina
in a high-calcium flux 1 pound of lime is required to combine with and
remove it as slag. A pound of lime (CaO) is derived from about 1.8
pounds of limestone (CaCOs); hence, if there is 4 pounds of silica plus
alumina in each 100 pounds of stone, not only is this 4 pounds of impurity
lost but, in addition, four times 1.8 pounds of pure limestone, which is
required to flux the impurity that is, a total of 11.2 pounds — and the
available carbonate in each 100 pounds of stone is only 88.8 pounds.
This may be expressed in a general formula as follows: If a equals the
percentage of silica (Si02) plus alumina (AI2O3) in the stone the available
carbonate is 100 — a — 1.8a or 100 — 2.8a. It is evident, therefore,
that a pure limestone is desirable for blast-furnace flux, the impure
content commonly being limited to 5 per cent.

Economic conditions greatly influence the use of pure or impure stone.
It is a peculiar circumstance that silica and alumina in a fluxing stone do
no real harm in a blast furnace; they merely make the stone less effective,
increase slag volume and fuel consumption, and retard production to a
limited extent. If the price differential between an impure stone and
one of high chemical purity is enough to offset these disadvantages an
impure stone may be preferred. The sulphur and phosphorus contents,
however, must be low. Sulphur should not exceed 0.5 per cent. The
highest permissible content of phosphorus for Bessemer iron is placed at
0.01 per cent, and for non-Bessemer iron at 0.1 per cent.

Opinions differ regarding the slagging effect of magnesia, but generally
the use of dolomites and high-magnesian limestones in blast furnaces is
not objectionable. High-magnesian flux has been used successfully at
Bethlehem, Pa., and Birmingham, Ala.^ and in many European furnaces.

Blast-furnace flux is a very important use for limestone, as about
900 pounds are required for each ton of pig iron manufactured. About
20,000,000 to 24,000,000 tons are used annuafly in United States iron
furnaces.

A relatively small tonnage of limestone is used in basic open-hearth
steel manufacture and in smelting lead, copper, and other nonferrous

CRUSHED AND BROKEN LIMESTONE 391

ores. Basic open-hearth slags are so high in lime and magnesia that the
formula for available lime reads 100 — 5.5a, whereas for blast-furnace
use, as shown previously, it reads 100 — 2.8a. It is evident, therefore,
that purer stone is required for steel-making than for blast-furnace flux;
the silica content usually is limited to 1 per cent, and the alumina content
to 1.5 per cent. As the chief purpose of basic open-hearth flux is to
remove phosphorus, and as magnesia is a poor remover of phosphorus, the
maximum permissible content of MgO usually is fixed at 5 per cent.

Owing to its enormous iron and steel industries western Pennsylvania
is the chief center of production for fluxing limestone. Michigan stands
second, not on account of its smelting industries, which are relatively
unimportant, but because highly efficient water transportation permits
shipment of the stone at low cost to many furnaces at Chicago, Gary,
Toledo, Cleveland, Buffalo, and other Lake ports. Ohio is third in
importance, chiefly on account of its many iron furnaces and its proximity
to the western Pennsylvania smelters. Alabama ranks fourth, as large
quantities of local stone are supplied to the Birmingham furnaces.
West Virginia is an important producer, providing supplementary sup-
plies chiefly for the ore furnaces of Pennsylvania. Arizona, Colorado,
Illinois, Indiana, New York, Utah, and Virginia produce substantial
tonnages.

Agricultural Limestone. — ^Limestone is important to agriculture as a
fertilizer, a soil conditioner, and a corrective of soil acidity. For these
purposes limestone of a high degree of purity is not essential, for although
impurities decrease the percentage of calcium or magnesium available
for improving the soil they are not injurious to plant growth. Therefore,
local limestones, though impure may be more economical than higher-
grade material from a distant source. Purity, however, is highly desir-
able. There is some difference of opinion regarding the suitabihty of
dolomitic limestones, but most authorities agree that magnesium has
value equal to calcium and that the agricultural value of stone may be
measured by the percentage of total carbonates present. From 2,000,000
to 2,500,000 tons of ground limestone are sold annually for liming land.

Miscellaneous Chemical Uses, alkali. — The manufacture of sodium
carbonate (soda ash) is an important chemical industry that consumes
4,000,000 to 5,000,000 tons of limestone a year. The Leblanc process,
one of the older methods, involves a reaction between limestone, sodium
sulphate, and carbon to form the desired sodium carbonate. A furnace
charge consists of about 100 pounds of salt cake (sodium sulphate),
100 pounds of limestone, and 50 pounds of coal dust. The magnesia
and silica content of the limestone should be low, or loss will ensue
through formation of insoluble residues.

A more modern method is known as the Solvay or ammonia soda
process. The principal reaction is in a brine (sodium chloride dissolved

392 THE STONE INDUSTRIES

in water) saturated with ammonia and carbon dioxide. The reaction
may be expressed as follows: NaCl + NH3 + H2O + CO2 = NH4CI +
NaHCOs. A second reaction for recovery of ammonia results from
treatment of the ammonium chloride thus formed with calcium hydroxide
(hydrated lime) according to the equation: 2NH4CI + Ca(0H)2 =
CaCU + 2H2O + 2NH3. Carbon dioxide used in the first reaction and
lime in the second are obtained by calcination of limestone in special
continuous kilns using coke as fuel. However, part of the requirement of
CO2 is obtained by calcination of the soda bicarbonate to form the normal
carbonate. Chemically pure limestone is desirable, though not essential.
About 11^ tons of limestone preferably in pieces 1 to 6 inches in size are
used for each ton of soda ash produced.

CALCIUM CARBIDE. — Calcium carbide (CaC2) is manufactured by
fusing an intimate mixture of powdered lime or limestone and coke in an
electric furnace. About 340,000 tons of limestone were used for this
purpose in 1929. About 2 tons of very pure limestone is required for
each ton of carbide made. The phosphorus content should be less than
0.01 per cent because phosphorus present in carbide used for producing
acetylene gas causes contamination with poisonous hydrogen phosphide.
The magnesia content should be less than 2 per cent, and the silica content
less than 3 per cent.

SUGAR. — ^Limestone is used in large quantities in refining beet sugar,
particularly in Colorado and Utah. More than 488,000 tons were used in
sugar factories in the United States in 1929. The limestone is calcined
into lime and used in the form of a milk-of-lime suspension to precipitate
impurities from the juices, or in the Steffens process to precipitate
sugar in the form of tri-calcium saccharate from impure solutions.
About 700 pounds of limestone are required for each ton of sugar, or,
expressed in another way, the lime requirement is about 2}^ per cent of
the weight of beets. Although lime rather than limestone is used in the
process, calcination at the refinery is desired because the carbon dioxide
is recovered for use in subsequent treatment of sugar-bearing juices.
Lump stone in 2- to 6-inch sizes is preferred. The presence of silica is
detrimental, as it becomes colloidal in the juices and forms a film on the
sugar crystals, retarding their growth and lowering their purity. Iron
oxide should be low, as it affects the color of the sugar. Much limestone
now used for this purpose averages 97 to 99 per cent calcium carbonate.
According to a specification issued by the U. S. Bureau of Standards,^
limestone (calcined before analysis) for the Steffens process should
contain at least 90 per cent of sugar-soluble lime and not more than 3
per cent of magnesium oxide.

"'' U. S. Bureau of Standards, Recommended Specifications for Limestone, Quick-
lime, Lime Powder, and Hydrated Lime for Use in the Manufacture of Sugar. Giro.
207, 1925, 0 pp.

CRUSHED AND BROKEN LIMESTONE 393

GLASS. — Either lime or limestone is used in the manufacture of glass
to supply the alkaline-earth compound necessary to its constitution.
Some manufacturers claim that limestone is preferable because the
evolution of carbon dioxide gas is beneficial in agitating the mix; others
prefer either quicklime or hydrated lime. Limestone of uniform grade
is required because of the rigid control necessary in composition of the
batch. In general, the lime content must not vary more than 2 per
cent from that stipulated in the contract. The iron content should be
low because of its coloring effect; for optical glass it must be practically
zero, whereas for the lower grades of bottle glass it may be as high as 0.5
per cent. Silica is not detrimental if moderate amounts are present, but
the sulphur and phosphorus content should be low. Combined calcium
and magnesium oxide requirements (on a calcined basis) are about as
follows: At least 89 per cent for bottle glass, 91 per cent for sheet glass,
93 per cent for blown glass, 96 per cent for rolled glass, and 99 per cent
for optical glass. Magnesium in limestone makes the glass batch more
difficult to melt but is advantageous in making some kinds of optical glass
and is preferred where certain types of automatic machinery are employed.

RUBBER. — Limestone or its products are used in two ways in rubber
manufacture — as whiting and as hydrated lime. Whiting is a bulking
agent or filler, performing the same function as clay or diatomite. It
also assists the rubber chemist in controlling hardness and elasticity in
building up his compounds. Some rubber contains as much as 25 to 30
per cent by weight of whiting. Pow^dered chalk is used in the manu-
facture of rubber cement.

PAPER. — Manufacture of paper from wood by the sulphite process
involves digestion of the pulp in an acid liquor under high temperature
and pressure until all constituents but cellulose are dissolved and removed.
The acid liquor, a solution of magnesium and calcium bisulphites,
together with more or less free sulphur dioxide, is obtained by treating
either milk of lime or wet limestone with sulphur dioxide prepared by
burning sulphur or iron pyrite in air. Lime manufactured from dolomite
or high-magnesian limestone is preferred for preparing acid liquor by the
milk-of-lime process, because magnesium bisulphite is said to be more
stable, more soluble, milder, and more effective in its chemical action
than calcium bisulphite. The limestone should be pure enough to give a
lime containing not more than 3 per cent total iron oxide, alumina,
silica, and other insoluble impurities.

A second method of obtaining acid liquor is by the Jennsen tower
system, whereby sulphur dioxide gas passes up through a tower packed
with limestone. Stone for this purpose should have preferably not more
than 2}^ per cent magnesium carbonate, although in some cases 3 per
cent may be tolerated, and rarely 5 or 10 per cent has been allowed.
Other impurities should not exceed 2}^ per cent, and a calcium carbonate

394 THE STONE INDUSTRIES

content of at least 95 per cent is recommended. The limestone should
also be virtually free from graphite or other carbonaceous material,
mica, and pyrite. Medium-grained stone in 8- to 14-inch fragments is
preferred. More than 273,000 tons of limestone were used in paper mills
in the United States in 1929. In addition, about 50,000 tons a year of
high-magnesian lime are sold to paper mills for use in the milk-of-lime
process.

FERTILIZER FILLER. — A Small amount of limestone is used with com-
mercial fertilizers as a diluting material or filler. It has the advantage
over inert fillers of possessing soil correcting and fertilizing properties.

STOCK FOOD. — Pulverized limestone is added to stock food as a bone
builder. Of limestone sold for miscellaneous uses in 1929, 25,270 tons
were classed as mineral food.

CARBON DIOXIDE. — Use of carbou dioxide has increased greatly during
recent years, chiefly because of its employment in solid form as a refriger-
ant. Adequate supplies are obtained principally from gas wells, coke
processes, or as a by-product of chemical and fermentation industries.
Dolomite is used to some extent as a source of carbon dioxide. In 1923
38,460 tons were so employed, but the amount has decreased steadily.
Since 1926 no figures are available because not more than two operators
reported. Vast quantities of carbon dioxide pass off from lime kilns and
this source of supply is receiving more serious attention.

MINERAL WOOL. — The name "mineral wool" or ''rock wool" is applied
to fine interlaced threads of calcium silicate. It is comparable with slag
wool or glass wool and used chiefly for heat insulation. One raw material
is argillaceous limestone, classified more properly perhaps as calcareous
shale. The stone is melted in a cupola furnace, and the slag thus formed
issues from a small opening and is blown with a steam jet into fine threads
which fall in a fluffy mass to the floor of a concrete chamber. Production
has grown rapidly. Numerous plants are springing up in various parts
of the country.

Uses of Dolomite and High-magnesian Limestone. — For the manu-
facture of a number of important products dolomite or high-magnesian
limestone is essential. Some of the uses for which a magnesium content
is essential or preferred are covered incidentally in preceding paragraphs,
and only the more important uses are mentioned in this section.

Eigh-magnesian Lime. — The use of limestone for manufacture of lime
has been covered in some detail on previous pages. For certain building
and chemical applications a high-magnesian lime is essential or preferred,
and the manufacture of such lime constitutes one of the important uses
of dolomite.

Refractories. — Dolomite and high-magnesian limestone are used
extensively as refractory linings in metallurgical furnaces, chiefly in

CRUSHED AND BROKEN LIMESTONE 395

basic open-hearth steel furnaces. Dead-burned material in various
forms is commonly used, although raw dolomite may be employed for
repair work. A dead-burned product is made by calcining dolomite or
high-magnesian limestone at about 1,500°C. either in a blast furnace or
in a special kiln. Virtually all the carbon dioxide is driven off, and the
calcium and magnesium oxides are sintered to an extent depending upon
the impurities present. Certain agents, such as iron oxide, alumina, or
silica, may be added to aid the sintering action.

There are two general ways of utilizing dolomite in furnace work;
it may be mixed with tar or a fluxing agent and applied as a monolithic
lining, or the calcined dolomite to which tar or suitable fluxing agents
are added may be shaped into bricks which are fired and then laid in the
same manner as other refractory brick.

Where dead-burned dolomite is used as a substitute for dead-burned
magnesite in basic furnace bottoms the raw stone should contain less than
1 per cent silica, less than 1.5 per cent combined iron oxide and alumina,
and at least 35 per cent magnesium carbonate, the remainder being
calcium carbonate. For this purpose dolomite is somewhat inferior to
grain magnesite; but it is satisfactory for repair work, which requires 40 to
50 pounds per ton of steel. More than 1,490,000 tons of dolomite were
used for refractory purposes in the United States in 1929. The amount
fell greatly in 1932 but reached 1,800,000 tons in 1937.

Technical Carbonate. — Technical carbonate, known also as basic
magnesium carbonate, block magnesia, or magnesia alba, finds its widest
utilization in the manufacture of pipe and boiler covering and for general
heat insulation, but it is also used in pharmacy, in the rubber trade, and
as a constituent of certain paints, varnishes, glass, printing inks, tooth
paste, and other commodities. It is manufactured chiefly from dolomite
by the Pattinson process or some modification of it. The process may be
outhned briefly as follows:

Dolomite is mixed with coke and calcined, and the carbon dioxide
thus driven off is recovered, purified, compressed, and cooled. The
calcined stone, consisting of a mixture of calcium and magnesium oxides,
is slaked in water and recarbonated with the recovered carbon dioxide.
The reaction results in formation of an insoluble calcium carbonate and a
soluble bicarbonate of magnesia having a composition expressed by the
formula Mg(HC03)2.H20. The calcium carbonate is removed by
filtration, and the filtrate is boiled, which drives off some of the carbon
dioxide and precipitates a white basic magnesium carbonate (the so-called
technical carbonate), a product somewhat variable in composition but
considered as having the formula 4MgC03.Mg(OH)2.5H20.

For manufacture of the so-called "85-per cent magnesia" molded
insulation, technical carbonate is mixed with about 15 per cent by weight
of asbestos fiber and possibly other bonding agents, molded into the

396 THE STONE INDUSTRIES

desired form, dried for jBve or six days, and finally cut to true dimensions
with special machinery. According to United States Bureau of Mines
figures, 84,750 tons of dolomite were used for manufacture of technical
carbonate in 1929, 111,740 tons in 1930, 80,820 tons in 1931, and 96,730
tons in 1937.

INDUSTRY BY STATES

General Distribution. — Limestones occur in every State. In some
States hundreds of deposits are quarried and prepared for the numerous
uses described on previous pages. The principal limestone areas of the
United States east of the Rocky Mountains are shown in figure 69.
The stone in these areas is of almost inestimable importance to industry,
and high-grade deposits are assets of great value to any community
within easy reach of possible consumers. The discussion of deposits
herein relates primarily to sources of crushed and broken stone. Deposits
of building limestone and marble described in previous chapters also are
potential or actual sources of crushed products, and to obtain an adequate
picture of the resources of any State the occurrences described in the
chapters on building limestone and marble also should be considered.

In following pages the distribution of limestone deposits is covered
by States in alphabetical order. For some of the more important States
tonnages or values for certain years are given to indicate the extent of the
limestone industries. Statistics of production for the several States are
published annually by the United States Bureau of Mines.

Alabama. — Chickamauga limestone of Ordovician age occurs in
parallel bands along river valleys in northern Alabama. The principal
occurrences are in Jones, Murphrees, Cahaba, Big Wills, and Coosa
Valleys. Although not quarried extensively it is sufficiently pure for
lime burning and for flux at several iron furnaces. Limestone of Ordo-
vician age is used for cement manufacture at Leeds, Jefferson County;
and at Ragland, St. Clair County. Cement plants at Birmingham use
Cambrian limestone with clay, shale, or slag.

Mississippian (Lower Carboniferous) limestone outcrops along the
sides and at the base of plateaus in the same general region occupied by
the Chickamauga beds but at a higher level. In many places it has a
high degree of purity and is, or has been, quarried extensively for iron-
furnace flux, notably near Rockwood, Franklin County; Bangor, Blount
Springs, and Graystone, Blount County; Rock Springs, Etowah County;
and Trussville, Tarrant, and Compton, Jefferson County. Dolomite for
refractory use also is quarried at Ketona and New Bessemer in this
county and calcined at Ensley. Longview and Newala limestones of
Ordovician age are the chief sources of stone for an important lime-burn-
ing industry centered in Shelby County south of Birmingham. Lime is
manufactured at Graystone, Blount County.

CRUSHED AND BROKEN LIMESTONE

397

398 THE STONE INDUSTRIES

White crystalline Cambrian or early Ordovician marbles occurring
in a belt in Talladega County are very pure, containing 99 per cent or
more calcium carbonate. Although they are used principally for building
and ornamental stone, they are suitable for furnace flux and have been so
used. Waste marble is crushed and pulverized for many uses.

The Selma Chalk of Upper Cretaceous age, extending across central
Alabama, is too friable for uses other than those demanding finely
divided material. The chalk beds have been quarried for whiting
manufacture, and a cement plant near Demopolis, Marengo County,
utilizes calcareous stone from this formation.

The St. Stephens limestone of Tertiary age crosses southern Alabama
and extends into Mississippi, where it is known as the Vicksburg lime-
stone. It is softer, more uniform in composition, and higher in calcium
than the Selma Chalk, While suitable for cement manufacture, little
of it is hard enough for high-grade crushed stone. A cement plant at
New Orleans, La. is supplied with stone from this formation. It is
quarried at St. Stephens on the Tombigbee River, Washington County,
and is shipped by water.

Aside from that employed in cement and lime manufacture about
nine tenths of all the crushed and broken limestone produced in Alabama
is used as furnace flux for the great iron industry of Birmingham. Crushed
stone for road material, concrete aggregate, and railroad ballast is
obtained chiefly from the Mississippian beds of northern and central
Alabama, with minor supplies from the Cambrian, Chickamauga, and St.
Stephens beds. Crushed stone is produced at Florala, Covington
County; and at Bridgeport, Jackson County,

A bituminous oolitic limestone of Mississippian age is quarried near
Margerum, Colbert County. The best of the quarry product, that which
is highest in bitumen, is enriched with the addition of 4 to 5 per cent
petroleum asphalt and sold as ready-mixed paving material. The
leaner product is sold as crushed stone. Lime is also manufactured at
Margerum.

Arizona. — The Arizona limestones have been developed only in a
small way. Cretaceous limestone is quarried near Douglas, Cochise
County, for production of flux, lime, crushed stone, and agricultural
limestone. Beds of Carboniferous age near Nelson, Yavapai County,
are utilized for the manufacture of lime. Stone from the same formation
is quarried at Perkinsville and calcined into lime, chiefly for use in the
Clarkedale smelters. A new lime plant is in prospect near Tucson,
Pima County. Its supply of stone is 7 miles west of the city. Lime
for metallurgical uses is manufactured at Radium, 7 miles north of
Miami, Gila County. By-product crushed stone and fines are used for
concrete aggregate and as stone sand and railroad ballast. Fluxing lime-
stone and small quantities of lime are produced at Tempe near Phoenix,

CRUSHED AND BROKEN LIMESTONE 399

Maricopa County. Some years ago the United States Government
operated a cement plant to supply material for building the Roosevelt
Dam, but upon completion of the project the plant was abandoned.

The smallness of the limestone industry in Arizona probably is due
more to restricted markets than to lack of raw materials.

Arkansas. — The principal limestone area of Arkansas lies in the
northern part of the State, in the Ozark Plateau region. High-calcium
rocks are represented in several formations, chiefly the Plattin, Kimms-
wick, and Ferndale, of Ordovician age; the St. Clair (Silurian); the Boone
and Pitkin (Mississippian) ; and the Brentwood and Kessler, of Penn-
sylvanian age. The Boone formation, with a maximum thickness of 425
feet, extending from White County to the Oklahoma Une, is the most
important. It is utilized for the manufacture of lime at Johnson,
Washington County; Ruddells, Izard County; Limedale, Independence
County; and St. Joe, Searcy County. Crushed stone and agricultural
limestone are manufactured at St. Joe, and stone quarried at Williford,
Sharp County, is used for agricultural limestone, aggregate, and ballast.
High-magnesian limestones of Lower Ordovician age are plentiful in the
Ozark region.

The Annona and Saratoga Chalk formations, both of Upper Cretaceous
age, occur prominently in Southwestern Arkansas. In places the rock is,
or closely simulates, true chalk. In past years it has been ground
quite extensively at Whitecliffs, Little River County, for agricultural
limestone and as whiting or whiting substitute for various filler uses.
The Annona attains a maximum thickness of 100 feet and is higher in
calcium than the Saratoga. It is used for cement manufacture southwest
of Nashville, Howard County. Cretaceous chalk will supply raw
material for a new cement plant which was under construction in 1932 at
Foreman, Little River County.

California. — Several geologic periods are represented by the California
limestones. In the more northerly section they are of Paleozoic age. In
the Coast Ranges the more important limestones are of early Jurassic
(pre-Franciscan) age; and in the Sierra Nevada foothill belt limestones
occur in lenses in the Calaveras (Mississippian) formation or its equivalent.
At several places in the central district north and east of San Francisco
Bay travertine bodies of recent age have been deposited by springs near
eruptive rocks. Some of them cover fairly large areas surficially but are
relatively thin.

Few extensive limestone deposits comparable with those in many
of the eastern States occur in California. Most of them are irregular,
lenticular bodies of variable magnesia content. Mining or quarrying
problems often are difficult, and many deposits are far from markets.
Numerous comparatively small areas of shelly, compact, or crystalline
limestones outcropping in many counties supply the chief raw materials

400 THE STONE INDUSTRIES

for important cement and lime industries, but various igneous rocks are
used more widely than limestone as sources of crushed stone. Never-
theless, crushed and pulverized limestones are utilized in many ways,
including stone for concrete aggregate, road construction, railroad ballast,
flux, refractories, glass and sugar manufacture, agricultural use, roofing
gravel, terrazzo, chicken grit, whiting, and whiting substitute. Both
the extreme northern part of California and the desert regions in the
south have larger deposits of limestone than the more populous parts of
the State, but owing to distance from markets and inadequate transporta-
tion facilities they have little or no commercial value.

Lime and crushed-limestone products sold in California in 1929 were
valued at over $1,100,000 and cement nearly $23,000,000. In 1937 the
figures were, respectively, $2,037,540 and $17,900,739.

Cement manufacture, centered in about a dozen localities, is an
important industry. Proximity to the extensive Los Angeles markets
has encouraged operation of large plants at Colton and Victorville and
construction of a new mill near Amboy, all in San Bernardino County.
Other large plants are near Crestmore and Oro Grande, both close to the
boundary between San Bernardino and Riverside Counties. Plants
near Los Angeles, Los Angeles County, and at Monolith, Kern County,
use local raw materials. San Juan Batista, San Benito County, is an
important center. Limestones adjacent to the coast are utilized in a
plant at Davenport, Santa Cruz County. Oyster shells pumped from
San Francisco Bay are used for cement manufacture at Redwood City,
San ]Mateo County. The shell deposits contain both the lime and clay
necessary for a proper cement mixture. Local limestone is consumed by a
plant at Co well. Contra Costa County. Some years ago limestone was
quarried for cement manufacture near Suisun, Solano County, but this
source of supply proved unsatisfactory. Until 1929 cement continued
to be manufactured in this locality, but the stone was shipped 85 miles
from Auburn, Placer County. Limestone obtained at El Portal, Mari-
posa County, is shipped 63 miles to a plant at Merced, Merced County.
An isolated area of limestone 12 miles long and about 3^ mile wide is
quarried for a mill at San Andreas, Calaveras County.

The most southerly lime plants of California are at Westend, Colton,
and near Ludlow, San Bernardino County. Lime is made from local
stone at Rincon and Felton, Santa Cruz County; and near Concord,
Contra Costa County. A plant using oyster shells as raw material began
operation in 1931 at Newark, Alameda County. A comparatively large
deposit of limestone crossing the western end of Tuolumne County is
utilized for lime manufacture at Sonora. Other lime plants are at
Diamond Springs and near Auburn, El Dorado County; and at Kennett,
Shasta County.

CRUSHED AND BROKEN LIMESTONE 401

Crushed and pulverized limestone products are obtained in quite a
number of important areas. As the deposits and production centers are
scattered, they are considered by counties, beginning in the southern
part of the State.

The limestones of Los Angeles County are used as fluxing stone and
asphalt filler and for road stone and sugar manufacture. San Bernardino
County deposits not only supply important cement and lime plants,
mentioned previously, but are quarried for various crushed-stone prod-
ucts at Westend and Victorville, Both limestone and dolomite quarried
near Monolith, Kern County, are shipped to Los Angeles markets. A
dolomite deposit near Lone Pine, Inyo County, is quarried for the
manufacture of alkali and other products and for use as a steel-furnace
refractory. Limestone obtained near Lemoncove, Tulare County, is
used principally in agriculture, for glass factories, and as a finely pulverized
product for the filler trade. A dolomite deposit near Salinas, Monterey
County, is worked at times for production of agricultural limestone and
refractories. At Hollister in the same vicinity limestone is quarried
and crushed for a variety of uses. For several years oyster shells have
been pumped from San Francisco Bay and conveyed to Alviso, Santa
Clara County, where they are ground for poultry grit and agricultural
limestone. The latter product is prepared also near Concord, Contra
Costa County; and at Sonora, Tuolumne County. An attractive red
travertine quarried near Bridgeport, Mono County, is used for terrazzo.
Crushed stone, fluxing stone, whiting substitute, and limestone for
chemical plants and sugar mills are obtained near Diamond Springs and
Shingle Springs, El Dorado County. The only important commercial
crushed-stone development in the comparatively large limestone deposits
of northern California is at Kennett, Shasta County, where smelter flux
and agricultural limestone are produced as occasion demands.

Colorado. — The Colorado limestones may be divided conveniently
into two groups — an eastern division, mostly of Cretaceous age, forming a
belt immediately east of the Front Range, and a second division, mostly
of Carboniferous age, lying west of this range. The Cretaceous forma-
tion consists of two members, the Niobrara and the Greenhorn; the
former is the more extensive.

The Niobrara limestone outcrops continuously from north of Fort
Collins to the middle of Douglas County, passing a little west of Denver.
From this location to a point 10 miles south of Colorado Springs the
outcrop is much interrupted by faulting and overlap of later formations.
It occupies quite a large area in southwestern El Paso County, the eastern
end of Fremont County, much of Pueblo, Otero, Huerfano, Las Animas,
Bent, Prowers, and Kiowa Counties, and a small area in Cheyenne
County. The best rock contains more than 90 per cent total carbonates,

402 THE STONE INDUSTRIES

but most of the formation is intermixed with shale. Some of the Car-
boniferous limestones west of the Front Range are pure enough for even
the highest-grade uses, but their location has discouraged commercial
development.

Exploitation of limestone deposits has been confined chiefly to a
central area, comprising El Paso, Pueblo, Fremont, and Chaffee Counties,
and all the quarries except those of Chaffee County are in the Niobrara
formation. Lime is manufactured at Manitou, El Paso County, and
produced in a small way at Pueblo, Pueblo County, but chief operations in
the latter county are near Stone City, where large quantities of furnace
flux are produced. In Fremont County stone is quarried at Concrete
and Portland for cement manufacture and at Canon City chiefly for
furnace flux, with smaller amounts for sugar factories, agriculture, and
highway construction. Dolomite is quarried for use as a refractory
lining in furnaces. Large quantities of fluxing stone for the smelting
industry at Pueblo are obtained from Carboniferous beds near Monarch
and Garfield in southern Chaffee County, where limestone for sugar
factories is also produced. At the travertine quarries near Salida
crushed material is sold and some lime is manufactured as by-products of
a building-stone industry. Magnesian limestones near Leadville, Lake
County, have been used for smelter flux.

The largest operation outside this central district is for the production
of stone to supply a cement plant at Boettcher near Fort Collins, Larimer
County. Stone for sugar mills is obtained from the Ingleside formation of
Carboniferous age at Ingleside.

A small production of lime and fluxing limestone has been reported
at Durango, La Plata County, near the southwest corner of the State
from beds of Carboniferous age.

Connecticut. — The only important calcareous rocks of Connecticut
are the Stockbridge crystalline limestones of Cambro-Ordovician age at
the western border of the State. They extend from Canaan in northern
Litchfield County southward beyond Danbury, Fairfield County. Small
outcrops of limestone reported in other parts of the State have little
commercial importance. As most of the Stockbridge limestone is
dolomitic it is unsuitable for cement manufacture. The crushed-lime-
stone industry of Connecticut is very small, because trap rock is much
more abundant and gives excellent service for road construction, concrete
aggregate, or railroad ballast.

The Litchfield County dolomites are utilized principally for lime
manufacture. At least five large lime plants near Canaan, East Canaan,
and New Milford have been in operation during recent years for the
manufacture of high-magnesian lime, with a minor output of low-
magnesian lime. There is also in this county a small production of
agricultural limestone and filler.

CRUSHED AND BROKEN LIMESTONE 403

Near Danbury, Bethel, and Redding, Fairfield County, both high-
magnesian and low-magnesian limestones are crushed or ground for road
stone, concrete aggregate, aggregate for the manufacture of cast stone,
poultry grit, agricultural limestone, and filler.

Delaware. — Small areas of crystalline limestone, mostly dolomitic
but with variable magnesian content, occur in the extreme northern part
of Delaware. They are of no present commercial importance.

Florida. — Calcareous rocks, all of Eocene age or later, are dis-
tributed widely in Florida. The Ocala limestone, of Eocene age, a
high-calcium rock occurring in very pure form in places, outcrops or is
available near the surface in the northern part of Jackson County, also
in central Florida over a large area comprising part or all of Suwannee,
Lafayette, Gilchrist, Alachua, Dixie, Levy, Marion, Sumter, and Citrus
Counties. The Marianna limestone, of Oligocene age, a high-calcium
stone of which some is soft and chalklike, occurs only in a small area at
Marianna, Jackson County. The Glendon limestone, also of Oligocene
age, a compact white rock, quite hard in places, occurs in the northwestern
part of Florida in parts of Holmes, Washington, and Jackson Counties,
and less extensively farther east in Madison, Suwannee, and bordering
counties. Tampa limestone, of Miocene age, a fairly hard, compact,
light gray to yellow rock, occurs typically in parts of the west-central
counties — Citrus, Hernando, Pasco, Pinellas, and Hillsborough. A large
area occurs also in northern Florida, in Suwannee, Hamilton, Madison,
Lafayette, Taylor, Jefferson, Leon, and Wakulla Counties. Coral and
oolitic limestones, of Pleistocene age, form the foundation of the keys
from Miami to Key West and border the eastern side of the Everglades.
Coquina and related shell limestones, of Pleistocene and Recent age,
occupy a large part of southern Florida, as well as sections of several
northern counties, particularly along the coast.

Chief production is in the Ocala formation of central Florida in
Marion, Levy, Alachua, and Citrus Counties. Near Reddick, Kendrick,
and Ocala, Marion County, limestone is quarried for road construction,
railroad ballast, and agricultural use. In response to the rapidly increas-
ing demands of building construction in Florida an important lime
industry has grown up during recent years at Ocala and Reddick. Several
large crushed-stone plants at Raleigh, and Williston, Levy County, and
York, Marion County are producing concrete aggregate and road stone.
Similar quarries are worked in Alachua County. A crystallized lime-
stone widely used for concrete aggregate is quarried at Crystal River,
Citrus County.

Chief developments in northwestern Florida are at Marianna and
Cottondale, Jackson County, where stone for agriculture and for highway
construction is quarried in large quantities. Another important produc-
tion center is Hernando County on the west coast. Limestone, of the

404 THE STONE INDUSTRIES

Tampa formation, is quarried near Brooksville and shipped by rail about
50 miles to Hooker's Point near Tampa, where it is manufactured into
cement in Florida's one cement plant. Crushed stone for railroad
ballast and concrete aggregate is also produced in the Brooksville district.

In Dade County, both near Miami and farther south at Naranja,
large quantities of limestone and dolomite are crushed for ballast and road
construction. Road stone is produced in Suwannee and Volusia Counties
and shell marl in Glades County. Road stone was produced near Fort
Lauderdale, Broward County, in 1930. Near Jacksonville, Duval
County, dredges are employed to obtain submerged calcareous building
sand, fertilizer sand, and oyster shells.

Georgia. — Commercial limestones of Georgia are confined principally
to the northwestern counties. Cambrian and pre-Cambrian crystalline
marbles of the Piedmont occur extensively in Fannin, Gilmer, Pickens,
and Cherokee Counties. The great marble industry of Georgia is
centered in Pickens County. West of this crystalline belt in counties
constituting the Appalachian Valley district of Georgia limestones are
abundant and of great economic importance. Geologically, they com-
prise the Conasauga and Beaver limestones, of Cambrian age; the Knox
dolomite, of Cambro-Silurian age; the Chickamauga limestone, of Silurian
age; and the Floyd and Bangor limestones, which have been assigned to
the Carboniferous period. Limestones, of Tertiary age, occur in many
parts of the great Central Plain area of southern Georgia, but most of
them are thin-bedded, argillaceous limestones or marls for which uses
are limited.

An industry of some importance has been developed in Pickens
County through utilization of pure high-calcium waste marble. It is
crushed for flux, aggregate, terrazzo, stucco, and poultry grit, ground for
agricultural use, or pulverized to an impalpable powder for filler or
whiting substitute. The marbles of Gilmer County at times are crushed
for road stone and terrazzo and the fine materials sold for soil improvement.

Limestones of Polk, Dade, and Bartow Counties of the Appalachian
Valley now have the greatest commercial importance. They furnish
calcareous raw materials for two large cement plants in Polk County,
one each at Portland and at Rockmart. Crushed limestone is also pro-
duced in this county. An important lime industry has been established
at Ladds near Cartersville, Bartow County. The quarry, which
provides stone for lime manufacture, also supplies a large tonnage for
road work, agricultural use, chemical applications, and asphalt filler. A
marble-flour industry of some importance is conducted at Cartersville.
Pure, high-calcium marble waste is shipped from Pickens County or from
Alabama and ground by wet or dry methods to produce marble flour for
the paint trade or for the varied uses of whiting and whiting substitute.
Road stone is produced at Graysville, Catoosa County.

CRUSHED AND BROKEN LIMESTONE 405

Coastal Plain limestones are quarried most extensively in Houston
County. They supply raw material for a cement plant at Clinchfield
and are quarried on a large scale near Perry to produce road stone.
Crushed-stone output is reported at times from Crisp County, and from
Sandersville, Washington County. The above producing areas are near
the center of the State. At Cuthbert, Randolph County, farther
southwest, travertine chips have been sold for terrazzo and ground
travertine for agricultural use.

Idaho. — Limestone deposits are to be found in many parts of Idaho,
those of chief value occurring in the northwestern and southeastern
counties. Cambrian Hmestones in Bannock County near the south-
eastern corner of the State have assumed importance owing to their
utilization for cement manufacture in a plant at Inkom, which began
operation in 1929. Crushed stone for lime manufacture, aggregate, and
flux has been produced near Pocatello in the same county, and stone has
been quarried in Cassia County for lime burning and for supplying
sugar refineries.

In northwestern Idaho lime is manufactured near Bayview in the
extreme northeastern corner of Kootenai County. Small amounts of
flux, chicken grit, and agricultural limestone are also produced in this
locality. A nearby quarry at Lakeview, Bonner County, supplies a large
tonnage of stone which is shipped to Spokane, Wash., for the manu-
facture of cement.

Limestones, probably of Triassic age, occur along Snake River in
Nez Perce County and have been quarried near Lewiston for agricultural
stone, chicken grit, stucco, and terrazzo. Farther east, at Orofino,
Clearwater County, the above products, as well as lime, are produced.
Pure limestone from Butte and Teton Counties is or has been shipped to
sugar factories in Idaho and Utah.

Illinois. — Commercial limestone deposits occupy about one third of
Illinois, including the northern end and a belt along the western and
southern borders. Scattered deposits of minor economic importance
occur in the remaining two thirds of the State. The northern area,
which contains an abundance of Ordovician and Silurian limestones,
includes Whiteside, Lee, La Salle, Grundy, and Kankakee Counties and
all those north of them. Most of the rock in this area is dolomitic. The
greater part of the crushed-stone industry of Illinois is centered in this
area, within a radius of 75 miles of Chicago. The western district com-
prises a narrow strip along the Mississippi and lower Illinois Rivers,
extending from Rock Island to Randolph County. Nearly all the
limestones are of Carboniferous age, chiefly Mississippian. The southern
district, comprising 10 counties, also contains prominent Carboniferous
limestone deposits, with minor exposures of Devonian age.

406 THE STONE INDUSTRIES

Illinois produces annually about 5,000,000 tons of crushed stone for
aggregate, road stone, and ballast and more agricultural limestone than
any other State. Important cement industries are situated at La Salle
and Dixon. Lime production is centered chiefly near Quincy, Cordova,
and Chicago.

The limestones of each district are described briefly by counties in
alphabetical order, but for the sake of brevity several counties where
production is small are omitted.

Northern District. — The dolomites of Boone County were worked quite
extensively at one time for local building stone, but at present they are
quarried only for crushed stone at Belvidere. An abundance of limestone
occurs in the Chicago district of Cook County. It is very important
because of the immense demand for road, street, and building material
in that populous center; it is used also as riprap for harbor work. Some
of the largest, best-equipped limestone plants in the country are to be
found at the suburban towns Bellewood, McCook, Lamont, La Grange,
Lyons, and Thornton. Lime is burned in and about Chicago; but much
of the raw stone is purchased, and some is obtained by water from
Calcite, Mich. A considerable quantity of the crushed limestone
utilized in the Chicago district is taken from the spoil banks of the canal
along the Des Plaines River. Railroad ballast, aggregate, filter stone,
and agricultural limestone are produced in large quantities at Elmhurst,
Du Page County, from thick dolomite beds adjoining those in Cook
County.

A fine-grained, dense, white dolomite occurs in Kankakee County and
is quarried extensively near Kankakee for road stone, concrete aggregate,
and agricultural limestone. Other small quarries are operated for local
use. Available limestone outcrops in Kendall County generally are
small, but locally the larger deposits are quarried for crushed stone and
agricultural limestone. La Salle County is characterized by an extensive
occurrence of low-magnesian Carboniferous limestone associated with
shale. It supplies raw material for an important cement industry near
La Salle and Oglesby. Two cement plants obtain their stone from open-
pit quarries, while one has extensive underground and open-pit workings.

Unlike most limestones of the northern district, the Platteville rock,
of Ordovician age, occurring in northwestern Lee County, is locally of the
high-calcium type. It is a fine-grained, dense, blue-gray stone in beds
2 to 40 inches thick. A large open-pit quarry supplies stone for a cement
plant at Dixon. Galena and Platteville dolomite occurs in the same
vicinity, but no crushed stone is produced, except occasionally from
numerous smajl quarries.

An abundance of Silurian limestone underlies practically the entire
area of Will County, but the overburden is too heavy for profitable
work, except near the western side. The rock is a white, light gray, or

CRUSHED AND BROKEN LIMESTONE 407

buff dolomite in beds aggregating about 200 feet or more in thickness,
though quarry faces are only 25 to 90 feet high. All the active quarries
are near Joliet, and some are very large and well-equipped. The chief
products are aggregate, road stone, and ballast, with a minor output of
agricultural limestone, filter-bed stone, and screenings. Crushed stone,
agricultural limestone, and lime are, or have been, produced from the
Galena formation at Rockford and elsewhere in Winnebago County near
the northern border of the State.

Western District. — Large, important lime industries are centered
near Quincy and Marblehead, Adams County. Keokuk-Burlington
(Mississippian) limestone occurs beneath so heavy an overburden that
it is available only along the river bluffs. Underground mining is now
generally followed. Part of the stone mined is used for lime manufacture
and the remainder crushed for aggregate and chicken grit or ground for
agricultural limestone and filler. A substantial production of riprap and
crushed stone is reported from Golden Eagle, Calhoun County; and also
from Grafton, Jersey County. High-calcium Mississippian limestone is
quarried near Eldred, Green County, for road material, concrete aggre-
gate, and agricultural limestone and flour, with a small production of
poultry grit.

Fine-grained gray to white Mississippian limestone occurs in Madison
County but is covered with a mantle of drift or loess averaging about
40 feet thick, except where the rock beds are exposed along the river
bluffs. The rock is quarried quite extensively for road material, concrete
aggregate, and agricultural limestone. One large quarry at the top of
the bluff provides stone for glass making and agricultural use and for
grinding to a very fine powder as a filler for paint, putty, rubber, and
asphalt. Road stone is quarried near Livingston.

Mississippian and Ordovician limestones occur in Monroe County.
The former are crushed for concrete aggregate, road material, ballast,
and agricultural limestone. The Ordovician limestones, however, are
regarded as too soft for road stone but are well-suited for aluminum-
refinery flux or for agricultural limestone uses. The chief production is
near Columbia and Valmeyer, where quarries are operated in the Missis-
sippian and Ordovician formations, respectively.

Limestones in Randolph County are available in thick beds along the
Mississippi River. Recent production has been confined principally to
the prison quarry at Menard, where agricultural limestone, concrete
aggregate, and road stone are obtained. Niagara (Silurian) limestone
is quarried for manufacture of lime and for crushed stone near Cordova,
northern Rock Island County.

St. Clair County, in the East St Louis district, is a very active quarry
center. Mississippian limestone outcrops extensively in the western
part of the county, and very large quarries are worked near Columbia,

408 THE STONE INDUSTRIES

at StoUe, and at Falling Spring 1)^ miles north of Columbia. The chief
products are aggregate, ballast, road stone, flux, chemical stone, and
agricultural limestone.

Southern District. — At Shetlerville, Hardin County; near Cypress,
Johnson County; and at Anna, Union County, a lower Mississippian
limestone, the massive Ste. Genevieve formation, is quarried for road
stone, concrete aggregate, agricultural limestone, and riprap.

Indiana. — Limestone occurs very widely in Indiana and is available in
many geological formations. Ordovician, Silurian, and Devonian lime-
stones appear in various counties in the southeast. The most important
are the Mississippian beds, which form a belt about 20 miles wide extend-
ing northwest through the central part of the State to the Illinois line.
Some limestone beds occur in the Upper Carboniferous (Pennsylvanian),
and Quaternary marls have been utilized quite extensively for the
manufacture of cement in northern Indiana.

Regardless of the well-known building-limestone industry the quarry-
ing of limestone and its manufacture into crushed-stone products are
important industries in Indiana. The value of crushed stone for aggre-
gate, road material, and ballast amounts normally to about $3,500,000 a
year. Indiana usually stands second to fourth in rank among all the
States as a cement-manufacturing center and normally about eight lime
plants are in operation.

The industries as now constituted may be considered most conveniently
by counties grouped in certain geographic areas, as follows: South and
southeastern, eastern, south-central, north-central, north and north-
western. Such grouping is in no sense permanent, for new developments
or the inactivity of some plants now producing might lead to an entirely
different alignment.

South and Southeastern Area. — A large output of aggregate, agri-
cultural limestone, and ballast originates near Marengo, northeastern
Crawford County, and at St. Paul and New Point, Decatur County.
Lime is produced in northwestern Harrison County not far from Mill-
town and crushed stone in the same district. Road stone and aggregate
are reported from Jefferson County; Washington, Daviess County;
Vernon, Jennings County; and Napoleon, Holton, and Osgood, Ripley
County. Salem, Washington County, is the center of a large lime and
crushed-stone manufacturing industry; and cement is manufactured at
Speeds, Clark County. Large quarries for road-stone production are at
Charlestown and Sellersbury, Clark County. There are mineral-wool
plants at Campbellsburg and Salem, Washington County.

Eastern Area. — Road stone, aggregate, and other products are
obtained at Linngrove, Adams County; and near Muncie, Delaware
County. The manufacture of lime is an active industry at Huntington,
Huntington County, where large quantities of ballast and road stone also

CRUSHED AND BROKEN LIMESTONE 409

are produced. Stone for aggregate, road building, and agricultural use is
quarried near Portland, Jay County; and near Ingalls, Madison County.
A calcareous rock high in silica and alumina occurring near Alexandria,
Madison County, near Wabash and Lagro, Wabash County, and at
Yorktown, Delaware County, is melted in cupola furnaces and manu-
factured into mineral wool. Quarries for the production of road stone
and aggregate, some of which are of large size, are situated near Albany
and at Ridgeville, northern Randolph County; near Glenwood, Rush
County; and at Bluff ton. Wells County.

South-central Area. — The greatest building-limestone industry in the
world is centered in Lawrence and Monroe Counties. Large, irregular
blocks of stone obtained in many quarries of both counties are sold as
riprap; and stone is prepared at various points for fiux, agricultural uses,
glass factories, road stone, and other applications. Lime is manufactured
at Bedford. These commodities are to be regarded chiefly as by-products
of the building-limestone industry. Road stone and aggregate are
produced at Spencer, Owen County, and a large output of similar products
originates near Greencastle, Putnam County. Important cement-
manufacturing industries are located near Greencastle, Putnam County,
and at Mitchell, Lawrence County.

North-central Area. — A large rotary-kiln lime plant operates at Kee-
port near Logansport, Cass County. Extensive quarries for production
of ballast, aggregate, and road stone are operated near Kenneth and
Logansport, Cass County; and at Kokomo, Howard County.

North and. Northwestern Area. — Rensselaer, Jasper County, and
Kentland, Newton County, are centers of crushed-stone production.
Railroad ballast and concrete aggregate are produced near Monon,
White County. At Stroh, La Grange County, a cement plant is in
operation, the chief raw material used being marl dredged from low-lying
areas. Marl formerly was used for the manufacture of cement much
more extensively than at present. A very large cement plant at Buffing-
ton, Lake County, uses no local stone; its raw materials consist of
slag from the Gary furnaces and limestone shipped from Calcite, Mich.

Iowa. — Limestones are very plentiful in Iowa. The oldest sediments,
those of Cambrian age, occur in the northeastern counties, and formations
of successively later ages appear to the west. The eastern Cambrian and
Silurian limestones are almost without exception high in magnesia, and
most of the Ordovician calcareous rocks are likewise dolomitic. The
Devonian limestone of east-central Iowa is magnesian in the northern
part and high-calcium in the south. Carboniferous limestones in central
and southern Iowa are low in magnesia. Chalk beds of Cretaceous age
occur in the valley of the Big Sioux River in the western part of the State.

Stone produced in Iowa in 1930 for concrete aggregate, road material,
and ballast was valued at more than $1,500,000, and almost all of it was

410 THE STONE INDUSTRIES

limestone. Cement manufacture is important; normally six plants
produce 6,000,000 to 7,000,000 barrels annually.

Limestone quarries are most numerous in eastern Iowa, active
operations being conducted in many counties. Quarries (some of which
are large and well-equipped) for the production of concrete aggregate,
road stone, agricultural limestone, ballast, and flux are operated more or
less continuously near Lansing, Allamakee County; La Porte City,
Black Hawk County; Waverly, Bremer County; Marquette, Clayton
County; Dubuque, Dubuque County; near Fayette, Fayette County;
Floyd, Floyd County; near Iowa City, Johnson County; near Stone City
and Anamosa, Jones County; and near Cedar Rapids, Linn County. A
lime plant is operated intermittently at Hurstville, Jackson County,
where riprap and some crushed and ground limestone are also produced.
A large cement plant is operated near Davenport, Scott County, using
local raw materials. Concrete aggregate, road stone, agricultural lime-
stone, and flux are also produced extensively in this county, particularly
near Buffalo and Linwood. A large road-stone quarry is situated at
Decorah, Winneshiek County.

Limestone industries of some magnitude are located in central Iowa.
Large quarries for production of concrete aggregate, road stone, ballast,
and agricultural limestone are in operation at Alden, Hardin County;
Legrand, eastern Marshall County; and Earlham, Madison County.
Quarries at Earlham also supply limestone and shale for cement
manufacture.

Two large cement plants are active at Valley Junction near Des
Moines, Polk County, but neither obtains its limestone near by. One
plant derives its supply from Earlham, Madison County, and the other,
which has obtained stone from Mississippian beds near Gilmore City in
Pocahontas County, later acquired a deposit near Winterset, Madison
County. Two of the largest cement plants in the State are at Mason
City, Cerro Gordo County, in northern Iowa. Both limestone and shale
are obtained from near-by quarries in Upper Devonian strata, which
also supply stone for aggregate and other uses. Pure limestone from
Osage, Mitchell County, is supplied at times to sugar factories. A large
cement plant at Gilmore City, Pocahontas County, uses local raw
materials. Aside from this plant and some small quarries, limestone is
utilized to a very limited extent in western Iowa. Quarries in the extreme
southeast at Keokuk, Lee County, and Douds, Van Buren County,
produce concrete aggregate, road stone, agricultural limestone, and flux.

Kansas. — Commercial limestones of Mississippian, Pennsylvanian,
and Permian age are confined to the eastern third of Kansas. Cretaceous
rocks in the central and western areas contain limestones, but little
economic use has been found for them. The lower Niobrara member of
the Cretaceous of western Kansas contains large reserves of chalk that

CRUSHED AND BROKEN LIMESTONE 411

may in future find an important place in industry. Cement manufacture
is important in eastern Kansas because the Pennsylvanian (Upper
Carboniferous) formation, which appears in the counties of the three
eastern tiers and part of the fourth tier, contains high-grade Hmestones
and shales and because markets and transportation routes are convenient.
Seven or eight plants are normally in operation, with a total annual
production of nearly 7,000,000 barrels. The total annual production of
crushed limestone for concrete aggregate, road construction, and railroad
ballast normally is about $1,000,000 at the quarries.

Except for one plant at Bonner Springs, Wyandotte County, not far
from Kansas City the cement industry is centered in the southeastern
corner of the State. Allen County has three plants, at lola, Humboldt,
and Mildred, respectively. Other plants are at Chanute, Neosho
County; Independence, Montgomery County; Fredonia, Wilson County;
and Fort Scott, Bourbon County. The only natural cement plant in
Kansas is at Fort Scott, and lime was manufactured here many years ago.

Crushed limestone for concrete aggregate, road building, railroad
ballast, and agricultural uses and to a limited extent for other applica-
tions is produced in the southeastern district, principally at Fort Scott,
Bourbon County; Humboldt and Moran, Allen County; Parsons, Labette
County; Moline, Elk County; Eldorado, Butler County; and Galena,
Cherokee County. In the northeastern area crushed-stone products are
obtained from several quarries near Kansas City, Wyandotte County; at
Atchison, Atchison County; near Topeka, Shawnee County; at Fort
Riley, Geary County; and in Douglas and Johnson Counties. In the
east-central part of the State a small output has been recorded from
Marion, Linn, and Osage Counties and from more extensive quarries
near Ottawa, Franklin County; and Garnett, Anderson County. Atchi-
son, Doniphan, and to a less extent Anderson, Cowley, Franklin, Shawnee
and Wyandotte Counties produce riprap, mainly for river and harbor
work.

Kentucky. — Limestones are widespread in Kentucky, as in most of the
Middle West States. Pennsylvanian (Upper Carboniferous) limestones
appear in many eastern and southeastern counties, as well as in the
northwest, but most of them are too thin or impure to have great com-
mercial importance. Mississippian (Lower Carboniferous) limestones
occur in eastern, central, and western Kentucky, while Ordovician
(Cincinnatian, Trenton, and Stones River) formations outcrop promi-
nently in the north-central region. As high-quality rocks are available
to transportation lines in many localities the crushed-stone industry is
large and widespread, with well-equipped, active quarries in more than
30 counties distributed in various parts of the State. Crushed stone
sold for concrete aggregate, road stone, and ballast was valued in 1929 at
more than $2,250,000 and in 1937 at about $2,555,000 at the quarries.

412 THE STONE INDUSTRIES

A large proportion was limestone. Although low-magnesian limestones
are plentiful there is only one cement plant in the State. Two large lime
plants are normally in operation. Aside from lime and cement, the chief
marketed commodities are concrete aggregate, road materials, railroad
ballast, and agricultural limestone, with a smaller output of riprap,
flux, screenings, and pulverized products.

Greatest activity is in the north-central counties, most of which have
within their boundaries one or more quarries for the production of crushed
stone. The one cement plant at Kosmosdale, in southwestern Jefferson
County, obtains its supply of limestone 30 miles to the west, in Meade
County. The stone is brought to the plant by barges on the Ohio River.
Stone for concrete aggregate, road construction, railroad ballast, and
agriculture, and to a small extent for other uses, is obtained from a group
of six or seven quarries near Louisville, Jefferson County; and from
large quarries near Clermont, Bullitt County; Tyrone, Anderson County;
Frankfort, FrankHn County; and Highbridge, Jessamine County. Less
extensive operations are reported from Nelson, Spencer, Oldham, Henry,
Owen, Scott, Fayette, Clark, Bourbon, Harrison, Kenton, Campbell, and
Fleming Counties. A considerable tonnage of riprap is obtained at times
in Campbell County.

Quarries for the production of crushed stone are established in
central Kentucky, notably at Danville and Perry ville, Boyle County;
at Trimble, Pulaski County; Jackson and Lincoln Counties; and at
Withers, Mount Vernon, and Sparks Quarry, Rockcastle County. The
largest, most continuously operated lime plant in Kentucky is at Pine
Hill, Rockcastle county. Its products are used in the chemical, metallur-
gical, and building industries, and for agriculture. A smaller lime plant
was in operation a few years ago at Campbellsville, Taylor County.

Crushed and broken limestone is produced extensively in western
Kentucky. Large quantities of riprap for use along the Ohio River are
quarried at Smithland, Livingston County. Quarries for production of
crushed limestone operate more or less continuously at Stephensburg and
Upton, Hardin County; in Larue County; at Irvington, Breckenridge
County; Russellville, Logan County; in Warren and Barren Counties;
at Hopkinsville, Christian County; Cerulean, Trigg County; Princeton,
Caldwell County; and in Crittenden County.

Supplies of roadstone and ballast are available also in eastern
Kentucky. Well-equipped quarries produce a large tonnage of crushed
limestone at Olive Hill, Lawton, and Carter, Carter County, and at
Yellow Rock, Lee County.

Louisiana. — Commercial limestones of Louisiana are limited to two
occurrences — one in Winn and the other in Evangeline Parish, Each
is part of the cap rock of a salt dome and is of indeterminate age. The
most important is the Winn Parish outcrop, about 3 miles west of the

CRUSHED AND BROKEN LIMESTONE 413

town of AVinnfield. The rock is a blue or in places a black and white
banded crystalline limestone, which has been used for lime burning,
concrete aggregate, railroad ballast, riprap, agricultural limestone, and
furnace flux. Since 1929 it has been utilized extensively for road building
and railroad ballast. A massive calcareous sandstone, probably of
Middle Eocene age, occurring near Coochie Brake in this county has been
described in literature as limestone. It has been used to a very limited
extent.

Two small outcrops of fine-grained, dark gray limestone, containing
small amounts of asphalt in pores and crevices, occur 7 miles southwest of
the village of Bayou Chicot, Evangeline Parish. They are parts of the cap
rock of the Pine Prairie salt dome. The rock was used for the manufac-
ture of lime before the Civil War and again for this purpose in 1934.

It is reported that limestone concretions of Tertiary age have been
used for the manufacture of crushed stone at Shreveport and for lime
burning near Natchitoches. A large cement plant at New Orleans uses
limestone and shale, which are quarried in Alabama and brought to the
plant by water.

Maine. — The most important limestone deposits of Maine are in the
ancient Taconic series of uncertain age near Rockland, Knox County.
They are surrounded by schists and other siliceous rocks and have been so
tilted from their original horizontal position that in some places the
bedding is practically vertical. As a result of metamorphism they are all
highly crystalline. Both high-magnesian and high-calcium rocks are
available. Resources of commercial stone are large and for many years
have supplied raw materials for an extensive lime industry. Seven lime
plants are, or have recently been, in operation in the district which
includes Rockland, Rockport, Union, and Thomaston. A large cement
plant at the latter town utilizes stone from this belt. A limestone outcrop
near Caribou, Aroostook County, in the northern part of Maine has been
utilized for manufacture of lime.

Crushed-limestone production in Maine is confined to a limited output
in the Rockland area of concrete aggregate, railroad ballast, agricultural
limestone and stone for paper mills. Numerous limestone areas appear
in other parts of the State, but lack of markets and scarcity of trans-
portation lines have discouraged development.

Maryland. — Maryland is well-supplied with limestones of many
geologic ages from pre-Cambrian to Carboniferous. The most ancient
are the crystalline varieties, probably of pre-Cambrian age, that outcrop
prominently in Carroll, Baltimore, and Howard Counties and less
extensively in Frederick County. Some of them, the Cockeysville
marble, for example, are magnesian, while others, such as those at Texas
and Union Bridge, are of the high-calcium type. Limestones of Cambrian
age — the Shady dolomite and Elbrook limestone— outcrop chiefly north-

414 THE STONE INDUSTRIES

east of Harpers Ferry; and the Stones River and Beekmantown limestones
of Ordovician age outcrop across Washington County, through, and west
of Hagerstown; and in Frederick County, near Frederick. Silurian
(Cayuga) argillaceous limestones occur in thin, persistent beds in Allegany
County and the western part of Washington County. Devonian
(Helderberg) limestone occurs above the Silurian in the same general
locations, Mississippian (Greenbrier) limestone outcrops only in Alle-
gany and Garrett Counties. Following is a brief review of the crushed-
limestone industries of Maryland, beginning with the eastern, or oldest,
formations.

A verde antique marble quarry is worked at Cardiff, northern Harford
County, and large tonnages of terrazzo chips, with smaller quantities of
aggregate and ballast, are produced as by-products. Ground waste
stone is used also for the manufacture of cement blocks.

The crystalline calcareous rocks of Baltimore County are utilized as
sources of marble, lime, and crushed stone. Large marble quarries have
been worked for many years at Cockeysville, and some of the waste
dolomitic marble is crushed and ground for poultry grit and agricultural
limestone. Lime is manufactured at Texas, and fluxing limestone,
stucco, and filter stone are obtained from several small quarries. Union
Bridge, Carroll County, is the center of a large cement industry, and lime
has been produced at Union Bridge and Westminster. Production of
crushed stone also is reported from this county.

Frederick County limestones have been utilized in many places.
Large lime plants are operated at Lime Kiln, Grove, Le Gore, and
Woodsboro, with smaller production at times near Thurmont and
Buckeystown. Quarries for production of concrete aggregate and road
stone are operated near Emmitsburg, Frederick, and Thurmont. Wash-
ington County is an important source of limestone products. Cement is
manufactured in large quantities at Security near Hagerstown, and both
lime and crushed stone are produced at Cavetown. Large quarries for
crushed-stone production are located near Hagerstown and Hancock.

In the extreme western section limestone is utilized chiefly as road
stone. The principal quarries are at Oakland, Garrett County; and
Cumberland and Mount Savage, Allegany County.

Massachusetts. — The calcareous rocks of Massachusetts consist
chiefly of Cambrian and Ordovician high-calcium and dolomitic marbles,
which are confined principally to Berkshire County at the western edge
of the State. High-calcium crystalline rocks are confined to the north-
western part of the county; nearly all of those in the central and southern
areas are dolomitic. Limestone quarries of commercial importance are
confined to Berkshire County.

Lime is a very important mineral product in Massachusetts, the State
ranking fifth in value of output in 1929 and fourth in 1932. Normally

CRUSHED AND BROKEN LIMESTONE 415

about eight plants, some large and provided with the most modern equip-
ment, are in operation. The chief centers of lime manufacture are
Adams, Farnams, Pittsfield, West Stockbridge, Lee, and Great Barring-
ton. Fluxing and agricultural limestone, stucco, and poultry grit are
produced from dolomite beds at Ashley Falls. Stone for furnace flux,
agricultural use, and paper manufacture is quarried at Pittsfield. Opera-
tions at West Stockbridge produce a large tonnage of agricultural lime-
stone, and this product, with fluxing stone, is obtained from quarries at
Lee. It is noteworthy that practically no calcareous rock is quarried for
concrete aggregate, road stone, or ballast in Massachusetts, as such needs
are supplied from trap and granite quarries.

Michigan. Geology of Limestones and Extent of Industry. — The chief
commercial limestones and marls of Michigan are of Devonian, Carbon-
iferous, and Quaternary ages. Most pre-Cambrian crystalline limestones
and dolomites which occur in the iron-ore districts in the western half of
the northern peninsula are too impure to be of economic importance,
though some relatively pure deposits are used in Dickinson County.

In the eastern part of the northern peninsula Ordovician limestones,
under the general name "Trenton," occur in Menominee, Delta, and
Schoolcraft Counties and extend eastward through the center of the
peninsula to St. Marys River. The rock, much of which is argillaceous,
is high in calcium in the upper part and magnesian in the lower part.
Its thickness ranges from 250 feet on Green Bay to 100 feet on St. Marys
River. Silurian (chiefly Niagara) limestone forms a belt 10 to 15 miles
wide from Garden Peninsula on the east side of Green Bay eastward along
the north shore of Lake Michigan and Lake Huron to the east end of
Drummond Island. Great thicknesses of high-grade rock are available.

In the southern peninsula Bass Island (Upper Silurian) impure
dolomite occurs in heavy beds in Monroe County. Dundee limestone of
Lower Devonian age occurs in a belt 2 to 9 miles wide running north-
east across Lenawee, Monroe, and Wayne Counties in southeastern
Michigan. It occurs also at the extreme north of the southern peninsula
on Mackinac and near-by islands and in adjacent parts of the northern
peninsula. Very thick deposits of Dundee limestone occur in a belt
from a point about 6 miles west of Rogers, Presque Isle County, southeast
to False Presque Isle Island. The largest area is near Rogers, where
there are apparently several hundred million tons of high-calcium lime-
stone, the upper 60 to 90 feet averaging from 97 to over 98 per cent
calcium carbonate.

The Traverse formation, also of Devonian age, lies above the Dundee.
It forms a belt 2 to 3 miles wide across southeastern Michigan and another
belt 12 to 15 miles wide around the northern end of the southern peninsula
from Alpena on Lake Huron to Little Traverse Bay on Lake Michigan.
From this point it forms a much narrower belt southwestward to Frank-

416 THE STONE INDUSTRIES

fort, Benzie County. This formation is not exposed in southeastern
Michigan but occurs in extensive outcrops in many parts of the northern
belt, where it ranges from 600 to 800 feet in thickness. In this belt the
reserves are practically inexhaustible. The Dundee and Traverse forma-
tions of the northern belt may be regarded as more productive of lime-
stone commodities than any other area of equal size in the United States.

A third important limestone formation, — the Grand Rapids of Car-
boniferous age — consists of the Bayport limestone at the top and the
Michigan series of shale, limestone, and gypsum at the bottom. Impor-
tant outcrops occur near Bayport and Pigeon, Huron County, on the
east side of Saginaw Bay; on the Charity Islands in Saginaw Bay; at
several places in Arenac County; Bellevue in Eaton County; and near
Portage River 5 or 6 miles north of Jackson. Both magnesian and high-
calcium beds occur in the Bayport, and, although in places it is sandy and
cherty, the purer beds range from 92 to over 96 per cent total carbonates.

In addition to the above massive limestones, Quaternary marl deposits
abound throughout the southern peninsula. Most of them are too small
for development, except as sources of agricultural limestone. They have
been widely used for cement manufacture, but this consumption has
greatly diminished. Some marls are fairly pure, although they rarely
contain more than 95 per cent total carbonates.

Limestone and its products constitute an important part of the
mineral wealth of Michigan, where sales of limestone, cement, and lime in
1929 were valued at more than $28,000,000. The value of these products
in 1937 was more than $16,400,000. It normally ranks third or fourth
among all the States as a producer of cement and limestone.

Cement Industry. — In normal times 14 to 16 cement plants are in
operation. The present situation differs widely from that 15 or 20 years
ago, when a large percentage of the cement production was from marl
plants. Because of the shortage of raw materials, increasing cost of
transporting marl from more and more distant points, low plant output,
obsolescence of plants, and difficulty of winter operation, a change to
other sources of raw material has taken place. Only about three marl
plants are now active.

The first group of plants considered comprises those that now use marl
and those that used it originally. Cement mills at Coldwater and
Quincy, Branch County, and at Fenton, Genesee County, still use this
material. A plant at Cement City, northwestern Lenawee County,
originally used it as the chief raw material; later a mixture of marl and
limestone was employed, and still later limestone shipped from a distance
replaced marl entirely. A cement mill at Chelsea, Washtenaw County,
used marl several years. This source of supply became unsatisfactory,
and stone shipped to Detroit from an upper lake port was brought to
Chelsea by rail. The plant was abandoned later. A mill at Newaygo,

CRUSHED AND BROKEN LIMESTONE 417

Newaygo County, at first employed marl but now uses limestone shipped
from Petoskey.

Only three cement plants in Michigan use local supphes of hard rock.
Mills at Alpena, Alpena County, and at Petoskey, Emmet County,
utilize the Traverse limestone, and a plant at Bellevue, southwestern
Eaton County, uses Carboniferous rock which occurs near by.

An interesting trend in the Michigan cement industry has resulted
from the enormous growth in production of limestone at lake ports in
Schoolcraft, Presque Isle, Emmet, and Alpena Counties because of
facilities for low-cost shipment. Large cement mills at Port Huron,
St. Clair County; Detroit, Wayne County; and Bay City, Bay County;
in addition to the Newaygo plant mentioned above, obtain most of their
raw materials from these northern lake ports.

A cement mill at Dearborn, Wayne County, uses furnace slag and
limestone screenings shipped from the northern quarries, and one at
Wyandotte in the same county uses in part calcium carbonate formed as a
by-product of alkali manufacture. The latter plant is the only one of its
kind in America.

Lime Industry. — When economic conditions are normal six to eight
lime plants operate in Michigan, all of them in the northern part of the
State. Several plants are located in Charlevoix and Emmet Counties in
the region surrounding Petoskey. The largest production is at Menomi-
nee, Menominee County, the stone being shipped by water from Rogers
City. Other large plants are situated near Manistique, Schoolcraft
County; and at Afton, Cheboygan County. Large quantities of lime are
burned at Sault Ste. Marie in the manufacture of calcium carbide.

Raw-limestone Industry. — The extensive deposits of high-grade lime-
stone close to deep water, the development of low-cost mass production,
and the invention of ships that unload automatically have effected
phenomenal development of large quarries near the north end of the lower
peninsula and on the north side of Lake Michigan. The movement of
limestone from Rogers City, Alpena, and Rockport on the lower peninsula
and Port Inland on the upper peninsula, to various points on the lower
lakes is comparable with the enormous shipments of iron ore from Great
Lakes ports farther north and west. The largest and most completely
equipped hmestone quarry in the world is at Rogers City, Presque Isle
County. The Dundee limestone is worked in tw^o benches, each about
55 feet high, and the quarry face is about 3 miles long. When the
author visited the quarry in 1927 electric shovels with 10-ton dippers
were employed for loading, and 16 trains were required to carry rock to
the crusher. The most modern methods of washing, screening, storing,
and loading from storage are used. Many thousands, even millions, of
tons of limestone are shipped from these ports to iron and steel furnaces;
to alkali, carbide, and other chemical works; and to cement and lime

418 THE STONE INDUSTRIES

plants at various lake ports. Large quantities of cement and lime are
manufactured in other States in plants that use Michigan limestone as raw
material. Smaller quantities of stone are shipped to various ports for glass
manufacture, agricultural use, and filler in asphalt and other products.

In Alpena County large quarries have been in operation at Alpena
and Rockport for many years, and another began operation at Alpena in
September 1931. Stone from Alpena is shipped to Wyandotte, Mich.,
and to Fairport, Ohio, for alkali manufacture, and the fines are made into
Portland cement at Alpena and Wyandotte. The stone from Rockport
is used chiefly for furnace flux and concrete aggregate.

Stone quarried in the Petoskey district is used not only for the manu-
facture of cement and lime, but also for furnace flux and for supplying
sugar mills, and stone for the latter use is also obtained at Afton, Cheboy-
gan County. At Bay Port, Huron County, a large quarry is operated
to produce road stone and aggregate, with a smaller output of furnace
flux and riprap.

Limestone is quarried at several points on the northern peninsula
for a variety of uses in addition to the manufacture of lime. At the
Fiborn and Ozark quarries in Mackinac County not far from Trout Lake,
large quantities of metallurgical stone are produced, with smaller
amounts for road construction, concrete aggregate, and railroad ballast.
The Ozark quarry produces dolomite for refractory use. At Manistique,
Schoolcraft County, stone for paper mills is the chief quarry product,
aside from lime. A very large limestone operation at Calspar north of
Hunts Spur is connected by a standard-gage electric railway 7 miles long
to a large modern crushing plant and harbor at Port Inland, on Lake
Michigan about 15 miles east of Manistique. Regular operation began
in the spring of 1930. Road stone and concrete aggregate are produced
at Wells and Gladstone, Delta County. At Randville and Felch, Dickin-
son County, special products are prepared for use in the m.anufacture of
cast stone and paints.

Large quarries are in operation also in southeastern Michigan.
Many thousand tons of road material, concrete aggregate, railroad
ballast, and agricultural limestone are quarried at Monroe, Monroe
County. At Sibley, Wayne County, a high-calcium stone is quarried,
chiefly to supply alkali works, although there is also a substantial produc-
tion of road stone, concrete aggregate, furnace flux, agricultural lime-
stone, and asphalt filler.

Minnesota. — Commercial limestones, all of Paleozoic age, occur only
in southeastern Minnesota. The oldest of them, the St. Lawrence, is a
sandy, buff rock, of Cambrian age, which outcrops near Judson and St.
Lawrence Siding on the Minnesota River and at many points along the
Mississippi bluffs from Red Wing to the Iowa line. The chief commercial
limestones are of Ordovician age and include the Oneota, Shakopee,

CRUSHED AND BROKEN LIMESTONE 419

Platte ville, and Galena formations. The Oneota dolomite, consisting of
heavy gray or buff beds 75 to 200 feet thick, occurs prominently at
Kasota and Mankato and almost continuously along the Mississippi
River and its tributaries from Red Wing to the southeastern corner of
the State. The Shakopee dolomite, which is 25 to 75 feet thick, lies
above the Oneota. It outcrops along the Minnesota River at Shakopee
and on the bluffs of the Mississippi River between St. Paul and Hastings.

The bluish or buff Platteville limestone, which is 12 to 30 feet thick
outcrops prominently along the Mississippi River in Minneapolis and
St. Paul and caps many hills in the southeastern counties. Important
outcrops of Galena occur only in Dodge, Mower, and Fillmore Counties,
where they supply quarry rock of good quality. Devonian limestones
appear only in Mower, Fillmore, and Faribault Counties. Quaternary
marls are plentiful.

Most Minnesota limestones are dolomitic, and many are nearly pure
dolomites. Low-magnesian limestones occur only in the Platteville,
Galena, and Devonian formations of the southeastern counties and
possibly in the Cretaceous near New Ulm, Brown County.

The limestone industry of Minnesota is comparatively small; in fact,
the annual value of the stone and its primary products other than building
stone totals less than one half million dollars. * Since the State has
abundant supplies of gravel, with trap rock and granite available in
certain localities, very little limestone is used on Minnesota highways.

Few supplies of low-magnesian limestones in locations advantageous
for Portland cement manufacture have yet been found, and no portland
cement has been made from local stone. Natural cement is manu-
factured at Mankato, Blue Earth County, and near Austin, Mower
County. At Duluth, St. Louis County, portland cement is manufactured
in a large mill supplied with raw materials which comprise furnace slag
from the iron furnaces at Duluth and limestone shipped from a Michigan
lake port. The largest lime plant in the State is at Duluth, and its supply
of stone is also obtained by water from Michigan. Lime is manufactured
from native stone at Mankato, Blue Earth County, and Le Roy, Mower
County.

Quarries producing crushed and broken limestone are confined to that
section of the State lying south and southeast of Minneapolis. Quarries
near Minneapolis, Hennepin County, supply considerable quantities of
road stone and concrete aggregate for use in that populous center, as
well as a small amount of ground limestone for agriculture and asphalt
filler. Similar products are obtained from quarries near St. Paul, Ramsey
County. Riprap for use along the Mississippi River is sold as a by-
product of a marble industry at Kasota, Le Sueur County, and derived
also from quarries at Mankato. Road stone and concrete aggregate are
obtained in the latter region and also at various points in Olmsted and

420 THE STONE INDUSTRIES

Fillmore Counties. Quarries on the river bluffs near Winona, Winona
County, supply road stone, concrete aggregate, agricultural limestone
and terrazzo chips. Small quantities of riprap are produced in Houston
County in the extreme southeast. Marl is used extensively on roads in
Crow Wing County and for liming soils in Stearns, Sherburne, and
Wright Counties. A small amount of crushed limestone for aggregate
is reported from Goodhue County, and riprap, flux and aggregate from
Rice County.

Mississippi. — The Mississippi Umestones are of Devonian, Carbon-
iferous, Cretaceous, Eocene, Oligocene, and Tertiary age. Siliceous
Devonian limestones and some fairly pure Mississippian (Lower Carbon-
iferous) calcareous rocks are exposed in Itawamba and Tishomingo
Counties in the northeast, but transportation facilities are inadequate.
Selma Chalk, of Cretaceous age, outcrops in a zone 10 to 30 miles wide,
passing southward from Alcorn County at the Tennessee line to Noxubee
County, where it turns eastward into Alabama. It is 250 to 900 feet
thick, and the best of it contains 70 to 84 per cent total carbonates. By
careful selection chalk of good quality might be obtained. The Ripley
limestone, of Upper Cretaceous age, and the Midway (Eocene) fossiliferous
limestone occupy small areas west of the Selma Chalk. A belt of Vicks-
burg (Tertiary) limestone crosses the State from Waynesboro to Vicks-
burg. The formation, consisting largely of alternating beds of limestone
and marl, is not well-suited for the production of crushed stone or lime,
although the combination might not be unsatisfactory for the manu-
facture of cement.

No cement or lime and very little crushed stone are produced in
Mississippi. The principal requirements for road work, concrete
aggregate, and railroad ballast are supplied from numerous gravel banks.
The Selma Chalk is quarried near Okolona, Chickasaw County, and the
Vicksburg limestone is now or has been quarried near Vicksburg, Warren
County; near Brandon, Rankin County; and on Limestone Creek, 3 or 4
miles northwest of Waynesboro, Wayne County. An important use of
the product is for liming the land.

Missouri. — Cambrian dolomite or magnesian limestone covers a
large part of southeastern Missouri, except the corner counties, where the
covering is Tertiary clay, gravel, and sand. Ordovician limestones
outcrop prominently near the Mississippi River northward from Cape
Girardeau to the northern part of Jefferson County. They cover western
St. Louis County and northern Frankhn County and appear in St.
Charles, Warren, Montgomery, and Callaway Counties on the north side
of the Missouri River. They are exposed again near the Mississippi
River farther north in Lincoln, Pike, Ralls, and Marion Counties. Most
of them are low in magnesium, and many of the deposits are of a high
degree of purity.

CRUSHED AND BROKEN LIMESTONE 421

Mississippian (Lower Carboniferous) limestone, much of which is
high in calcium and contains a low percentage of impurities, covers
extensive areas along the Mississippi and Missouri Rivers and in the
southwestern counties. It is used widely for lime and cement manu-
facture and as crushed stone at various points along the Mississippi
River, notably in Ste. Genevieve, St. Louis, St. Charles, Lincoln, Marion,
Lewis, and Clark Counties. In the southwest it is utilized most exten-
sively in Greene and Jasper Counties. Almost all northern and western
Missouri is covered by the Pennsylvanian (Upper Carboniferous) series,
which consists chiefly of shales and sandstones but contains some beds
of limestone, which are utilized principally in Clay and Jackson Counties.

The manufacture of cement and lime and the quarrying of limestone
for use in crushed and broken form are important industries in Missouri;
the normal annual sales value of such products is approximately $19,000,-
000. In 1929 the value of cement sold exceeded $11,500,000, and the
marketed value of lime at the plants exceeded $2,300,000. In 1937 these
totals were $7,041,016 and $2,326,928, respectively. The State ranks
third as a producer of lime; it is exceeded only by Ohio and Pennsylvania.
Missouri leads all other States in production of riprap, used for shore
protection along the Missouri and Mississippi Rivers.

Normally five large cement plants at widely separated points are in
operation. A plant at Hannibal, Marion County, in the northeast, and
two plants near St. Louis utilize Mississippian limestone. A cement
mill at Independence, Jackson County, near the western edge of the
State, uses Pennsylvanian limestone, and one near Cape Girardeau in
the southeast employs Ordovician rock.

Thirteen to 18 lime plants operate in Missouri under normal business
conditions. The most productive district is at Ste. Genevieve, Mosher,
Brickeys, and nearby territory, Ste. Genevieve County, where large,
well-equipped plants produce high-calcium lime from the Spergen
formation of Mississippian age and the Kimmswick limestone of Ordo-
vician age. Lime plants are operated also at Centaur and Glencoe,
St. Louis County, and at Byers and Glen Park, Jefferson County.

A second important lime-producing center is in the southwest, where
high-grade Mississippian limestone is available. Large plants are
situated at Ash Grove, Galloway, and Springfield, Greene County, and
smaller plants at Pierce City, Lawrence County, and near Osceola,
St. Clair County. Burlington limestone, of Mississippian age, is utilized
for burning lime in a third district at Hannibal, Marion County.

Quarries for the production of crushed and broken limestone are
widely scattered throughout the State, the east-central district around
St. Louis and west-central district in the neighborhood of Kansas City
being the most productive. Numerous quarries in and about the city of
St. Louis provide many thousand tons of riprap for river work, and also

422 THE STONE INDUSTRIES

crushed limestone for street and highway construction and for concrete
aggregate. Quarries at Clayton, Florrisant, Glencoe, Jefferson Barracks,
Koch, Vigus, University City, and other small towns in St. Louis County
also contribute to the demands of this populous center. Large quarries
at Weldon Springs, St. Charles County, supply railway ballast, road stone,
agricultural limestone, and riprap, the last commodity being produced
also at Bernheimer, Warren County. At Elsberry, Lincoln County,
limestone is quarried for glass factories, agricultural use, and filler and
whiting substitute. Auxvasse and Cedar City, Callaway County, and
Berger, Franklin County, are important centers for production of
riprap. Large quantities of riprap are produced at Louisiana, Pike
County; Columbia and other points in Boone County; and in Moniteau,
Montgomery, and Ralls Counties. Dolomite for refractory use is
quarried near Bonne Terre, St. Francois County.

Quarries in Ste. Genevieve County produce stone for riprap, concrete
aggregate, and road building, also finely ground stone for coal-mine
dusting, paint, asphalt filler, and other industrial uses. At Cape Girar-
deau, Cape Girardeau County, in southeastern Missouri large quantities
of road stone, concrete aggregate, and agricultural limestone, and a small
amount of riprap are produced, while at Neely's Landing in the same
county riprap is the leading product.

Moderate supplies of road stone and agricultural limestone are
obtained at White Bear and Hannibal, Marion County, in northeastern
Missouri. Stone from these quarries is used also for poultry grit,
asphalt filler, mineral-food mixtures, and whiting substitute. Riprap
and crushed stone are produced in Lewis and Clark Counties. The
largest operations in central Missouri are for production of riprap, nota-
bly at Osage City, Cole County; Blackwater and near Arrow Rock,
Cooper County; Wellington, Lafayette County; Glasgow, Howard
County; and Slater, Saline County. A substantial production of road
stone, concrete aggregate, railroad ballast, and agricultural limestone is
also obtained at Blackwater.

Western Missouri is well-supplied with limestone quarries. In
Greene County the important lime industry of Ash Grove and Galloway
and the building-stone industry of Phenix are supplemented by a moder-
ate production of crushed stone and agricultural limestone. Road
stone concrete aggregate, and agricultural limestone are produced in
large quantities from several quarries near Springfield. At Carthage,
Jasper County, both crushed stone and ground products are made, the
latter including poultry grit, terrazzo and roofing chips, and asphalt
filler. Carthage stone is also supplied to glass and sugar factories and to
metallurgical works. Some of the largest quarries in the State and at
least a dozen smaller ones are active in and near Kansas City and Inde-
pendence, Jackson County. Like the quarries around St. Louis their

CRUSHED AND BROKEN LIMESTONE 423

principal activity is the production of road and street-paving material
and concrete aggregate for use in public works and building construction.
Riprap is produced in smaller amount, and agricultural limestone and
other ground products are also marketed. Near-by quarries at Birm-
ingham, Smithville, Excelsior Springs, Missouri City, and South Liberty,
Clay County; St. Joseph, Buchanan County, and at Amazonia, Andrew
County, are sources of similar products.

Montana. — The most valuable limestones of Montana are confined to
the western part of the State. They occur in massive beds flanking the
mountain ranges from Red Lodge in Carbon County through Livingston
in Park County northwest to the principal mountain ranges west of
Great Falls in Lewis and Clark and Powell Counties. In places the beds
are nearly vertical. The purest limestones are of Mississippian (Lower
Carboniferous) age; but impure limestones (dolomitic, siliceous, and
argillaceous) of Jurassic, Pennsylvanian, Devonian, Cambrian, and
pre-Cambrian Age are widespread and of great thickness. Cretaceous
rocks, outcropping in many places throughout the eastern two thirds of
the State, contain lenses and concretions of limestone that have been
used locally for lime burning.

Tw^o cement and two lime plants have recently been in operation.
The chief production of crushed limestone is for smelter flux; road
material and concrete aggregate are next in importance, while somewhat
smaller amounts are quarried for riprap and for supplying sugar refineries.

Jefferson is usually a productive county. The quarry centers are at
the northern end near East Helena and in the south at Limespur where
interesting underground methods are used. The stone is of exceptional
purity, much of it exceeding 98 per cent total carbonates ; on this account
the larger part of the output is used for flux or for sugar manufacture,
though some of it is used for road stone and concrete aggregate.

Pure, high-calcium limestone quarried near Sappington, Gallatin
County, is used for sugar refining, while the more siliceous rock at
Trident near Three Forks is quarried for cement manufacture. Lime is
manufactured at Lost Creek 7 miles west of Anaconda in Deerlodge
County, and a considerable quantity of fluxing stone, with a minor output
of crushed stone, is also obtained in this county. Lime used chiefly for
metallurgical purposes is manufactured near EUiston, Powell County.
Stone for sugar manufacture is quarried at Drummond, Granite County,
and for both sugar refineries and for use in crushed form in Cascade
County. The only noteworthy riprap quarry in the State is in Mussel-
shell County. Upper Paleozoic limestone is used for cement manu-
facture at Hanover, Fergus County. Calcite from veins occurring near
Springdale, Park County, is utilized in stock and chicken food.

Nebraska. — Limestones of greatest economic value in Nebraska are
the Pennsylvanian and Permian, of Carboniferous age, and the Niobrara,

424 THE STONE INDUSTRIES

of Cretaceous age. Pennsylvanian limestones outcrop chiefly in the
southeastern counties — Sarpy, Cass, Lancaster, Otoe, Johnson, Nemaha,
Pawnee, and Richardson. Available Permian limestones are confined
chiefly to Gage County. The Niobrara formation is exposed most
prominently along the Missouri River in northeastern Nebraska, and
from Alma to Superior in the Republican Valley at the southern edge of
the State. Representative analyses of this chalklike formation show a
total carbonate content of 67 to 96 per cent. As a source of commercial
chalk it has possibilities that have not yet been developed.

The limestone industries of Nebraska are relatively small and confined
to southeastern counties; of these, Cass and Sarpy are the most produc-
tive. Pennsylvanian limestone is utilized at Louisville, Cass County,
for cement manufacture and for production of concrete aggregate, road
stone, riprap, railroad ballast, flux, and agricultural limestone. Most of
the stone is obtained from underground mines. Riprap is quarried near
Nehawka. At Weeping Water riprap and stone for poultry grit and for
glass making are produced, with large amounts of pulverized limestone
for use in rubber, putty, paint, and asphalt. Riprap, road stone, and
concrete aggregate are produced north of Louisville in Sarpy County;
and Permian limestone is, or has been, quarried for similar purposes at
Blue Springs, Gage County. The Niobrara chalk formation is utilized
for cement manufacture at Superior, Nuckolls County.

Nevada. — Limestones, chiefly of Carboniferous age, outcrop in various
places in the eastern third of Nevada. Crystalline limestones are
reported in Esmeralda and Elko Counties. Owing to difficulty of
transportation and limited markets few quarries have been operated.
Chief developments are in Clark County, where both high-calcium and
magnesian limestones are available. High-calcium and dolomitic rocks
are utilized extensively at Sloan; the chief products are limestone for
sugar mills and open hearth furnaces, ground limestone, and a smaller
quantity of crushed stone. Lime and crushed stone have been produced
also at Jean. A small output in other counties is used locally only.

New Hampshire. — Very little limestone occurs in New Hampshire,
and there has been no recent production. Occurrences are confined
almost exclusively to the Helderberg (Devonian) formation of Grafton
County. Crystalline limestones of variable composition were utilized
many years ago for lime burning at various points, notably Littleton,
Haverhill, and Lisbon.

New Jersey. — The Franklin Hmestone of pre-Cambrian age is the
calcareous rock of greatest commercial importance in New Jersey. It is
white, is coarsely granular and crystalline, and ranges in composition from
nearly pure calcium carbonate to dolomite. It is utilized chiefly for
cement manufacture in Sussex and Warren Counties. The Jacksonburg
limestone of Ordovician age outcrops prominently in Warren County, and

CRUSHED AND BROKEN LIMESTONE 425

its principal use is for the manufacture of cement. Although some of it
runs as high as 95 per cent calcium carbonate it contains numerous
shaly layers.

Limestones occur in various other formations, but the only one of
present economic importance is the Kittatinny magnesian limestone of
Cambrian and Ordovician age. It occurs in thick, highly foliated beds,
which are most readily available for commercial use in Sussex, Warren,
Somerset, and Hunterdon Counties.

Cement is the most important limestone product of New Jersey.
Large mills are in operation at New Village and Vulcanite, Warren County,
and until recent years it was manufactured also at Alpha near Vulcanite.
The so-called cement rock is an argillaceous limestone which approaches
the proper composition for a cement mixture as it occurs in nature.

In Sussex County a large quarry in the crystalline beds near Newton
produces stone for a great variety of uses, including road stone, concrete
aggregate, fluxing stone, agricultural limestone, poultry grit, and pulverized
material for asphalt filler and various other applications. Fluxing stone
for iron furnaces at Bethlehem, Pa., has been quarried at McAfee, but the
quarry is now inactive. Limestone is obtained at times from quarries
near Hamburg and Sparta. Lime plants were at one time operated at
Hamburg and McAfee.

Dolomitic limestone occurring at Peapack, Somerset County, is used
for lime burning and also for road stone, concrete aggregate, agricultural
limestone, and asphalt filler. Similar stone for highway construction is
quarried near Clinton, Hunterdon County.

New Mexico. — Limestones of Ordovician, Silurian, Carboniferous,
and Cretaceous age occur in New Mexico; however, very little is known
of their extent and quality. Inadequate transportation and restricted
markets have discouraged developments. Aside from a small lime plant
near Meadows, San Juan County, the only noteworthy activity is at
Montezuma, San Miguel County, where lime, road stone, and concrete
aggregate are produced.

New York. General Geology and Production Centers of Limestone. —
Except for the southern counties along the Pennsylvania border lime-
stones are distributed widely in New York and constitute the most
important source of crushed stone. Crystalline limestones of pre-
Cambrian age occur extensively on the west side of the Adirondacks
in Lewis, Jefferson, and St. Lawrence Counties. Cambrian limestones
and dolomites occur in Herkimer and Saratoga Counties and in a small
area in the Champlain Valley. The Chazy limestone of Ordovician age
outcrops at various points in the eastern Adirondacks from Saratoga
County north to the Canadian boundary, attaining its maximum thick-
ness in Clinton County. It is gray and finely crystalline and contains
95 per cent or more calcium carbonate.

426 THE STONE INDUSTRIES

The Mohawkian formation (including Trenton, Black River, and
Lowville), also of Ordovician age, is very important commercially.
One belt beginning in the Champlain Valley near Whitehall extends
through northern Washington County to Glens Falls in southern Warren
County and continues into Saratoga County. Another belt begins in the
Mohawk Valley and extends with gradually increasing width northwest
through Oneida, Lewis, and Jefferson Counties to the St. Lawrence
River. The formation occurs also along the lower Hudson River near
Poughkeepsie. The Mohawkian limestone is gray to almost black and
is generally pure and low in magnesia. It is used for cement and lime
manufacture and is crushed and pulverized for various purposes.

The Clinton, Lockport, and Guelph members of the Niagara group of
Silurian age extend from Otsego County northwestward to Oneida Lake
and westward through Rochester to the Niagara River. The Clinton,
the most important member, is quite argillaceous in the eastern section
but becomes purer to the west and occurs as a high-grade limestone in
the Niagara district. It is important as a source of fluxing stone for the
Buffalo smelters, although most of their supply is now obtained by
water from Michigan lake ports. The Lockport limestone is quarried
near Rochester. Cayugan limestone, also of Silurian age, occurs in
Erie, Schoharie, Onondaga, and Ulster Counties. This formation is
suitable for the manufacture of natural cement in Ulster and Erie
Counties.

The Helderberg and Onondaga limestones of Devonian age are exten-
sive and have great economic importance. The belt extends from Buffalo
in Erie County eastward to Oneida County, and southeast to Albany
County, where it curves south through Greene, Ulster, eastern Sullivan,
and Orange Counties to the Delaware River. It is generally a bluish
gray, massive limestone containing some chert. It is used widely as
crushed stone and for cement and lime manufacture. The most extensive
as well as the purest rocks occur in the central and southern areas of the
belt.

The Tully limestone, also of Devonian age, occurs in a very irregular
belt intersecting the Finger Lakes of central New York. It is thin,
somewhat argillaceous, and best-adapted for crushed stone or for cement
manufacture, but is suitable for lime manufacture in places. Quaternary
marls occur extensively in central and eastern parts of the State. New-
land^^ describes New York limestones in greater detail.

The principal centers of limestone production are in the Hudson
River Valley, for the New York market; in Oneida, Madison, and
Onondaga Counties, for the central New York markets; and in Monroe,

" Newland, D. H. The Mineral Resources of the State of New York. New York
State Museum Bulls. 223, 224, 1919, pp. 255-272.

CRUSHED AND BROKEN LIMESTONE 427

Genesee, and Erie Counties, for the demands of Buffalo, Rochester, and
other western markets.

New York ranks second as a producer of crushed Kmestone, and it
normally ranks fourth as a producer of cement. The total value at the
plant of cement, lime, and limestone sold in the State in 1929 exceeded
S30,000,000. It had dropped to about half that amount in 1932.

Cement Industry. — The most productive district is in the Hudson
River Valley, where cement is now, or has recently been, manufac-
tured at Cementon, Alsen, and Catskill, Greene County, and near
Hudson, Columbia County, on the opposite side of the river. In eastern
New York cement plants are also operated at Glens Falls, Warren
County; and at Howes Cave, Schoharie County. There is a plant for
the manufacture of natural cement at Rosendale, Ulster County. James-
ville, Onondaga County, and Portland Point, Tompkins County, are the
productive areas of central New York. Cement requirements of the
western part of the State are supplied principally from plants at Akron
and at Buffalo, Erie County. Part of the limestone supplied to plants in
this district is shipped by water from Michigan Lake ports.

Lime Industry. — Lime plants are operated in many parts of New York,
but few are large. The largest eastern centers are at Chazy, Clinton
County; at Glens Falls, Warren County; and at Dover Plains, Dutchess
County. A few small plants operate in Washington, Fulton, and
Ulster Counties. In the central area lime is manufactured at Jordan-
ville, Herkimer County; and dead-burned dolomite is prepared for
refractory uses at Natural Bridge, Jefferson County. A small output
is reported from Seneca County. Lime plants are operated at Oakfield,
Genesee County, and at Buffalo, Erie County, in western New York.
The Buffalo plant is supplied with stone from Michigan.

Manufacture of Crushed and Ground Limestone. — Quarries for the
manufacture of crushed-limestone products are most numerous in
eastern New York. At Chazy and Plattsburg, Clinton County, in the
northeastern corner of the State, limestone is quarried for flux, road
stone, and concrete aggregate. Stone for the last-named uses is quarried
at Glens Falls and other points in Warren and Washington Counties.
Pure rock obtained at Bald Mountain in the latter county has been sold
to paper mills. Other important quarries for production of concrete
aggregate and road stone are operated at Saratoga Springs, Saratoga
County; Mayfield, Fulton County; Cranesville, Montgomery County;
Schoharie, Schoharie County; and Feura Bush, Ravena, and South
Bethlehem, Albany County. In the southeastern counties several
exceptionally large limestone quarries supply part of the enormous
demands of the district in and about the city of New York. They are
within easy distances of this extensive market and have the advantages
of both rail and water transportation. There is a notable quarry at

428 THE STONE INDUSTRIES

Stoneco, Dutchess County, and a large new plant has recently been
built at Clinton Point near by. Other large quarries are worked near
Marlboro, Ulster County, on the opposite side of the Hudson River;
near Newburgh, Orange County; Tomkins Cove, Rockland County;
and Verplanck, Westchester County.

In north-central New York crushed limestone for aggregate, flux,
paper mills, agriculture, and other uses is produced at Norwood, Ogdens-
burg, Gouverneur, and Richville, St. Lawrence County. Crushed lime-
stone is also produced at Watertown, Jefferson County; Jordan ville and
Newport, Herkimer County; and Oriskany Falls and Prospect, Oneida
County. Madison County is a producer of limestone for road work,
concrete aggregate, agricultural uses, railroad ballast, and riprap. The
chief quarry centers are Munnsville, Perryville, and Canastota. Excep-
tionally large quarries are worked in Onondaga County at Rock Cut
and Jamesville, the major output of the latter locality being used for alkali
manufacture. Auburn, Cayuga County, is another important quarry
center.

The construction and industrial activities of western New York are
well-supplied with limestone. Concrete aggregate, road stone, and
ballast are quarried near Geneva, Ontario County. Exceptionally large,
well-equipped plants produce crushed dolomite at Penfield and Rochester,
Monroe County. Quarries at Le Roy and Stafford, Genesee County, and
at Lockport and Gasport, Niagara County, supply fluxing stone for
Buffalo furnaces in addition to large quantities of the usual crushed-stone
products. The requirements of the Buffalo district are supplied mainly
from quarries at Akron, Buffalo, and Cheektowaga, Erie County.

North Carolina. — The great post-Cambrian crystalline belt that
provides extensive limestone resources in Alabama, Georgia, Tennessee,
and Virginia passes west of North Carolina, therefore her resources are
confined to relatively limited deposits of Cambrian and pre-Cambrian
limestones, with Eocene, Miocene, and Quaternary shell rock and marls.
Both high-calcium and magnesian limestones occur in many counties in
the western section of the State, mostly in valleys, and are so covered
with soil that careful surveying and prospecting are required to determine
their extent and quality. Granite is so abundant in North Carolina that
limestone is a relatively unimportant source of crushed stone. Produc-
tion is confined almost exclusively to the southwestern counties. No
cement is manufactured in the State.

Fletcher, in northern Henderson County, is the most active center of
limestone production. Quarries in this locality supply materials for a
substantial output of lime, crushed stone used chiefly for highway work,
and a smaller amount of agricultural limestone. Crushed stone and
agricultural limestone are produced at Ashford, McDowell County.
Agricultural limestone and road stone are produced at times in Madison

CRUSHED AND BROKEN LIMESTONE 429

County. Small quarries are operated in New Hanover County, and
crushed marble is produced in Cherokee County. Coastal Plain marls of
eastern North Carolina are used locally for soil improvement.

North Dakota. — The only limestone formation of North Dakota is the
Niobrara, of Cretaceous age, a soft chalklike rock usually intermixed with
clay. No cement, lime, and crushed stone are now produced in the State.
A cement plant was operated some years ago in Cavalier County, but the
rock was found to be too low in lime.

Ohio. General Geology and Production Centers of Limestone. — The
oldest limestone formation of Ohio is the Trenton (Ordovician), which
underlies much of the State but appears at the surface only in Clermont
County. Cincinnatian limestone, also of Ordovician age, occurs in
southwestern Ohio, in Hamilton County, and in several other counties to
the east and north. There are numerous limestone layers, most of them
limited to a foot or less in thickness and in general quite impure. Brass-
field (Silurian) limestone somewhat irregular in composition occurs in
southwestern Ohio, principally in Prebble, Montgomery, Miami, Clark,
Greene, Clinton, Highland, and Adams Counties.

Niagara limestone, of Upper Silurian age, occurs prominently in
western and northern Ohio. Exceedingly pure dolomites prevail in this
formation and constitute much of the raw material for the most pro-
ductive lime-manufacturing area in the country. The Lower Helderberg
(Devonian) limestone of western and northern Ohio is chiefly dolomitic
and supplements the Niagara as a source of raw material for the manu-
facture of magnesian lime. It is widely used also as crushed stone.
Corniferous (Devonian) limestones occur in a belt in central Ohio extend-
ing from Pickaway County to Erie County and in a second belt in the
northwest passing through Pauling, Henry, Wood, and Lucas Counties.
Some of them are dolomitic, while others may have a magnesia content
as low as 7 or 8 per cent. They are used for lime burning, for flux, and
in crushed and pulverized form.

The Maxville (Lower Carboniferous) limestone is associated closely
with the coal fields. It generally ranges from 80 to 90 per cent calcium
carbonate, but most of it lies too far below the surface to have economic
value. It outcrops or is easily available only in Perry, Muskingum,
Vinton, Jackson, and Scioto Counties. The Putnam Hill (Upper
Carboniferous) limestone lies in the western part of the coal fields. It is
used for cement manufacture in Stark County, but in other places the bed
usually is too thin.

In contrast to these two limestones, the Vanport or Ferriferous
(Upper Carboniferous) limestone occupies a place of importance eco-
nomically. It occurs in two areas, the northernmost of which is best
developed in Mahoning County, where it is quarried for furnace flux.
The southern area, which is the more outstanding, appears prominently in

430 THE STONE INDUSTRIES

Vinton, Jackson, Gallia, Lawrence, and Scioto Counties in southern
Ohio. The beds range from 4 feet or less to a maximum of about 16 feet
in thickness. The rock, which is relatively high in iron and low in
magnesia and carries 80 to 90 per cent calcium carbonate, is used for
cement manufacture in Lawrence County. In southeastern Ohio the
Monongahela (Upper Carboniferous) limestone occurs quite extensively
but is used to a limited extent only, as it is rarely pure, and most of it
high in magnesium. Quaternary marls occur less extensively than in
Michigan and Indiana.

Limestone is the raw material for a series of basic industries of vast
importance in Ohio. With an output valued at $4,000,000 to $9,000,000
a year the State overtops all others by a wide margin as a producer of
lime. Ohio usually ranks fifth or sixth in order in the manufacture of
cement. The total sales value of cement, lime, and limestone (other
than building stone) at the quarry, mine, or mill was approximately
$33,000,000 in 1929 but had dropped to less than $25,000,000 in 1937.

Lime Industry. — Normally, 25 to 30 lime plants are in operation in
Ohio. The most productive area in the State or, in fact, the whole
country is the Toledo district, embracing Ottawa, Sandusky, Seneca, and
Wood Counties. Unless otherwise specified, all the plants in this district
produce high-magnesian lime that is particularly well-adapted for use in
finishing coat plaster. Plants at Clay Center and Genoa, Ottawa
County are among the largest in the world, that at the former locality
having 53 shaft and 1 rotary kiln, and that at the latter having 40 shaft
and 2 rotary kilns. Another large plant at Marblehead in this county
produces high-calcium and low-magnesian limes. Gibsonburg and
Woodville, Sandusky County, are also very large lime centers, three to
four plants operating near each town. One of the Woodville plants has
53 shaft kilns. Dead-burned dolomite is manufactured at Bettsville
and Maple Grove, and lime is made at Tiffin, Seneca County. Luckey,
Wood County, is another source of supply.

A second district farther south reports substantial production of
lime, although most of the plants are smaller than those in the district
already mentioned. Lime plants are located at Carey, Wyandot County;
Forest, Hardin County; Delaware, Delaware County; Columbus,
Franklin County; and Cedarville, Greene County; while three plants
operate near Springfield, Clark County. Low-magnesian lime is the
product of Delaware and Franklin Counties.

A large quarry at Peebles, Adams County in southern Ohio provides
dolomite which is manufactured into lime and dead-burned products at
Kenova, West Virginia. In northeastern Ohio small plants near Bolivar,
Stark County, and at Zoar, Tuscarawas County, burn agricultural lime
for local use.

CRUSHED AND BROKEN LIMESTONE 431

Cement Industry. — About 10 cement plants operate in widely scattered
localities in Ohio. Along the northern border of the State there are
plants at Toledo, Lucas County; at Castalia and Baybridge, Erie County;
and at Painesville, Lake County. A plant at Middlebranch, Stark
County, is supplied with Putnam Hill rock from a ledge about 12 feet
thick overlying a thin seam of coal. A cement mill at Fultonham,
Muskingum County, uses stone from an open quarry, but the supply is
now supplemented from a recently opened underground mine. Two
plants at Osborn, Greene County, utilize the Brassfield high-calcium
limestone. Carboniferous limestones are used for cement manufacture
in two localities in Lawrence County. At Superior a heavy capping of
sandstone permits removal of Vanport limestone from underground
drifts a short distance below the surface. At Ironton a vertical shaft
penetrates the Maxville limestone at a depth of 450 feet, where an
elaborate room-and-pillar mining system is followed.

Crushed- and Ground-limestone Industry. — Broken-, crushed-, and
pulverized-limestone industries are extensive and consist of many
widely distributed units. For convenience the productive counties are
grouped by their geographic location. For the sake of brevity, no men-
tion is made of places where production was small or quarries were
inactive in recent years.

The first region described embraces a group of counties in north-
western Ohio. A small quarry is worked near Paulding, Paulding County ;
and several quarries operate near Cloverdale, Fort Jennings, Kalida,
Ottawa, Rimer, and Pandora, Putnam County. A large quarry is
operated near Findlay and smaller ones near Arlington, Findlay, Vanlue,
and Williamstown, Hancock County. Chief centers of production in
Wood County are North Baltimore and Portage, with smaller outputs
at Bloomdale, Luckey, Rudolph, and other points. Almost the entire
production of the quarries in the counties mentioned is used for road
stone and concrete aggregate. There are very extensive developments
at Waterville, Holland, Sylvania, and Whitehouse, Lucas County. The
products are concrete aggregate, road stone, a substantial output of
railway ballast, agricultural limestone, and stone for sugar mills. Quarries
at Genoa, Clay Center, and Marblehead, Ottawa County, produce many
thousand tons of crushed stone, and the last town also is an important
center for the production of fluxing stone, agricultural limestone, and
asphalt filler. Stone for refractory use and paper mills is produced in
considerable quantities at Clay Center. Quarries near Bellevue and at
Gibsonburg, Fremont, and Woodville, Sandusky County, produce very
large quantities of crushed stone for road work and concrete aggregate.
The pure dolomite is marketed extensively as furnace flux, refractory
stone, and agricultural limestone and also is employed in glass factories.
Stone is quarried extensively for similar purposes at Bascom, Bloomville,

432 THE STONE INDUSTRIES

and Maple Grove, Seneca County. Large fluxing-limestone quarries
are operated on Kelleys Island, Erie County; and at Marblehead, Ottawa
County. Equally large quarries at Sandusky produce road stone,
concrete aggregate, ballast, and agricultural limestone. Part of the
crushed-stone output of this northwestern district is produced in con-
junction with the lime industry.

A second group of counties considered is in western and western-
central Ohio. Large quarries near Delphos and at Middle Point, Van
Wert County, produce about equal quantities of railroad ballast and
stone for highways and concrete aggregate. Allen County has large
quarries at Lima and Bluffton, with several smaller ones at Westminster
and other points. Limestone obtained at Piqua, Miami County, is used
for a variety of products, including concrete aggregate, road stone,
fluxing stone, and poultry grit; in pulverized form it is used for agricultural
limestone and filler for putty, asphalt, and other products. Other large
quarry centers for railroad ballast, road stone, and concrete aggregate
are at Ada, Dunkirk, Forest, and Kenton, Hardin County; Marion,
Marion County; and Carey, Wyandot County. Crushed stone is
produced at East Liberty, Belle Centre and Rushsylvania, Logan County,
and east of West Mansfield, Union County. High-magnesian limestone
is crushed for road work and agricultural use at Celina and Rockford,
Mercer County. There are several smaller quarries in the latter counties
and also near Lewisburg, Preble County; Centerville and Phillipsburg,
Montgomery County; and Springfield, Clark County.

Important limestone industries are located in central and north-
central Ohio. Quarries at Spore, Crawford County, and Delaware and
Radnor, Delaware County, produce substantial quantities of road stone
and aggregate. One of the largest quarries in the Middle West, at
Columbus, Franklin County, produces crushed stone for ordinary
purposes, and in addition large quantities of stone for furnace flux and
alkali manufacture, smaller amounts for glass factories and chicken grit,
and pulverized stone for agricultural use and as filler in asphalt and rubber.

In southwestern Ohio large quarries are operated at Melvin, Clinton
County, and north of Greenfield, Fayette County. Crushed stone is
produced also in Hamilton, Clermont, and Adams Counties. Limestone
quarrying is relatively unimportant in the eastern half of Ohio. Produc-
tion, except for local use, is confined chiefly to Fultonham, Muskingum
County, where crushed stone is produced in conjunction with a large
output of limestone for glass and cement manufacture, and to a quarry
near Adena, Harrison County, the products of which are crushed stone
and agricultural limestone.

Oklahoma. — The oldest limestone of Oklahoma is the Arbuckle, of
Cambrian and Ordovician age, which occurs in two areas. The larger
is in the Arbuckle Mountain district, including parts of Coal, Pontotoc,

CRUSHED AND BROKEN LIMESTONE 433

Pittsburg, Atoka, Garvin, Murray, Carter, and Johnston Counties;
the smaller area is in the Wichita Mountains, in Comanche and Kiowa
Counties. The formation is 4,000 to nearly 8,000 feet thick, and the
central part is dolomitic. It has been described in some detail in a
recent report.^® Heavy limestone beds, of Simpson (Ordovician) age,
occurring prominently in the eastern and central parts of the Arbuckle
Mountains and at the north end of the Criner Hills, have little commercial
value at present. The Viola limestone, of Ordovician age and the
Hunton, of Silurian and Devonian age, occurring in small areas adjacent
to the Arbuckle formation, for the most part are low in magnesium but
are inclined to be irregular in composition and somewhat siliceous.
Mississippian (Lower Carboniferous) limestone, occurring in several
southeastern counties, and Pennsylvanian (Upper Carboniferous), which
is available in several counties in the northeastern section of the State, is
suitable for the manufacture of cement and use as crushed stone.

The leading limestone industry of northeastern Oklahoma is the
manufacture of cement at a large plant near Dewey, Washington County,
where crushed stone for roads is also produced. Limestone is crushed
chiefly for railroad ballast at Avant, Osage County. Large quarries for
production of concrete aggregate, road stone, and smaller amounts of
ballast, agricultural limestone, and asphalt filler are worked at Garnett,
Sand Springs, and Price, Tulsa County. Lime has been produced at
Sand Springs, in this county. Road stone is quarried in Rogers County
and stone for glass factories in Adair County.

Southeastern Oklahoma likewise has one large cement plant at Ada,
Pontotoc County; the limestone used is obtained from an open-pit quarry
about 6 miles away. Crushed stone is produced in the same quarry.
Very large quarries and crushing plants for production of concrete
aggregate, road stone, and railway ballast are located at Crusher, Murray
County; in southwestern Coal County not far from Bromide; at String-
town, Atoka County; and at Hartshorne, Pittsburg County. Asphaltic
limestone occurs near Dougherty, Murray County. Limestone produc-
tion of western Oklahoma is confined to one quarry at Richards Spur,
Comanche County, where road stone and railway ballast are prepared in
large quantities.

Oregon. — In Oregon limestones occur principally in three widely
separated localities — the southwestern, the northwestern, and the north-
eastern corners. Those of the southwestern area, occurring in Jackson
and Josephine Counties, are of Devonian, Cretaceous, and probably
Carboniferous age. Some contain only 5 per cent or less impurities and
therefore are suitable for Hme burning and chemical uses. Most lime-
stones in the northwestern counties are impure. Very pure rock in beds

*^ Decker, C. E., and Merritt, C. A., Physical Characteristics of the Arbuckle Lime-
stone. Oklahoma Geol. Survey Circ. 15, 1928, 54 pp.

434 THE STONE INDUSTRIES

at least 100 feet thick occurs in Baker County in the northeastern corner
of the State. Deposits are found also in Grant, Union, and Wallowa
Counties in the same section.

Very little limestone is consumed for road work or concrete aggregate
in Oregon, as demands for such uses are supplied chiefly by trap rock and
gravel. In the northeastern area lime and cement are manufactured at
Lime, in southeastern Baker County; and lime is manufactured also
at Enterprise, Wallowa County. In southwestern Oregon limestone is
quarried at Gold Hill, Jackson County, for lime and cement manufacture,
and stone from the same deposit is supplied to paper mills. Josephine
County reports production for agricultural use, for paper mills, and for
asphalt filler. The limestone industry of the northwestern area is
represented by a cement plant near Oswego in northwestern Clackamas
County.

Pennsylvania. Reasons for Leadership. — The limestone industries of
Pennsylvania are far in the lead of those in all other States. Their
preeminence is due to the presence of an abundance of high-grade stone
and availability of very extensive markets. Enormous iron and steel
industries use many thousand tons of fluxing and refractory stone. The
State is populous, and its numerous cities and towns require a network of
connecting roads. The road building involved in its wide system of
highways consumes great tonnages of both limestone and cement.
Extensive building construction demands crushed stone, cement, and
lime, and the last product is used widely also in numerous chemical
plants. Coal-mine dusting, agriculture, and many manufacturing indus-
tries also require large supplies of limestone. Not only are its home
markets extensive, but the State occupies a strategic position for supply-
ing outside markets in many industrial centers.

Geology of Limestones and Extent of Industry. — ^Limestones are wide-
spread in Pennsylvania, but high-grade rock of greatest commercial
importance is confined to the central and southeastern counties and to an
area north of Pittsburgh near the western border. The oldest limestone,
which is of pre-Cambrian age, occurs in relatively small outcrops in the
southeast, notably in Chester, Bucks, Berks, and Northampton Counties.
Most of it is coarsely crystalline. It has been used to a limited extent
for crushed stone. Cambro-Ordovician limestones occur very promi-
nently in many parts of central and southeastern Pennsylvania. Their
great thickness and easy solubility compared with associated formations
have made them the most important valley-forming limestones of the
State. A prominent valley in this rock passes across the State through
Easton, Bethlehem, Allentown, Reading, Lebanon, Carlisle, and Cham-
bersburg. Lancaster Valley and York Valley are of similar origin. The
beds are folded, and outcropping belts run, in general, northeast and
southwest. The rock is variable in both structure and composition, as

CRUSHED AND BROKEN LIMESTONE 435

the lower beds are generally higher in magnesium than the upper strata.
Rock of a high degree of purity is used in many places. An argillaceous
phase constitutes the famous "cement rock" in the Lehigh Valley district.
The Cambro-Ordovician formation furnishes much of the raw materials
for cement, lime, and crushed stone in the State.

The Helderberg and Tonoloway (Devonian-Silurian) limestones occur
in south-central Pennsylvania in great, longitudinal folds that have been
worn down by erosion. They appear as narrow curving, contorted bands
running, in general, northeast and southwest. Frequently the rocks
are siliceous and argillaceous, but very pure stone has been found in
some localities. Hundreds of quarries are, or have been, worked in these
beds for the manufacture of agricultural limestone, crushed stone,
furnace flux, and lime. Other Silurian and Devonian limestones occur
but have minor economic importance.

Carboniferous limestones are very widespread throughout the. north-
central and western half of the State. Occurrences are most numerous
in the southwestern section and with the exception of the Vanport forma-
tion become less abundant and in general of less economic value toward
the north and northeast. The stone is used locally in southwestern
counties for lime burning and road construction. The Vanport (Penn-
sylvanian) limestone, which corresponds with the Ferriferous formation
described in the section devoted to Ohio, is the most important of the
Carboniferous rocks. It is used extensively in Armstrong, Butler, and
Lawrence Counties for furnace flux, crushed stone, and the manufacture
of lime and cement.

Detailed information on Pennsylvania limestones is given by Miller. ^^

The total value at the plant of limestone, cement, and lime produced
in Pennsylvania in 1929 exceeded $75,000,000. Crushed and broken
limestone, aside from that used for cement and lime manufacture, sold
during the same year was valued at about $13,937,000, a larger sum than
was obtained for similar products in any other State. Pennsylvania far
exceeds all other States as a cement producer; the sales value exceeded
$55,000,000 in 1929 and $31,000,000 in 1937. Pennsylvania has a greater
number of lime plants than any other State, but in value of output
Ohio usually leads by a wide margin. Pennsylvania stands second, with
a sales value at the plant of nearly $5,900,000 in 1929 and $5,117,733 in
1937. The total value of crushed and broken limestone and its primary
products, cement and lime, reached about $50,000,000 in 1937.

Cement Industry. — Twenty-seven or twenty-eight cement plants
normally are in operation in Pennsylvania. Geographically they fall
into two groups. The southeastern, which is by far the more important
area comprises Northampton, Lehigh, Berks, Montgomery, and York

«^ Miller, B. L., Limestones of Pennsylvania. Topog. and Geol. Survey of Penn-
sylvania Bull. M 7, 1925, 368 pp.

436 THE STONE INDUSTRIES

Counties, while the western or smaller area includes Allegheny, Butler,
and Lawrence Counties. Conditions strongly favor maintenance of a
great industry in southeastern Pennsylvania. First, the abundant supply
of raw materials consists chiefly of so-called cement rock, an argillaceous
limestone in which the silica, alumina, and lime occur in approximately
the proper proportions for a cement mixture, though in many places the
composition must be adjusted by addition of a small percentage of lime-
stone or shale. The rock is easily quarried and pulverized, and the
intimate natural mixture of limestone and clay is advantageous. Second
the district is located centrally with respect to large markets and is well-
served with railroads. The easy availability of fuel supplies is a third
favorable factor. This combination of advantages has resulted in
development of a more extensive cement industry in Lehigh and North-
ampton Counties than is to be found in any other area of equal size in the
world.

In Northampton County there are 4 plants near Nazareth, 3 near
Bath, 2 at Northampton, and 1 each at Martin's Creek, Stockertown,
Siegfried, and Sandt's Eddy. The cement mills of Lehigh County are
at Coplay, West Coplay, Egypt, Fogelsville, Ormrod, and Cementon.
Mills are operated also at Evansville, Berks County; West Conshohocken,
Montgomery County; and York, York County. The dry process of.
manufacture is most generally used. All plants in the district obtain
their rock from open-pit quarries.

In Lawrence County, in the western district, limestone from open-pit
quarries is supplied to cement mills at Walford Station and New Castle,
while stone for a mill at Wampum is obtained from an underground mine.
In Butler County the Vanport limestone is mined underground for a
cement mill at West Winfield. Two cement plants operate near Pitts-
burgh, Allegheny County, one at Neville Island and one at Universal.
Both employ furnace slag to which Vanport limestone is added.

Lime Industry. — Pennsylvania has more lime plants than any
other State; about 130 were active in 1929. As many of them which
supply agricultural limestone for local use have a relatively small output,
the aggregate production is much less than that reported from the 28
lime plants of Ohio. However, many large, well-equipped plants are
operated. In the following brief reference to individual locations, many
small plants that are chiefly of local interest are necessarily omitted.
The most active production centers are in southeastern and central
Pennsylvania.

In the southeastern section lime is produced in Adams County not
far from Hanover. One of the largest high-magnesia lime plants of the
State is at Devault, Chester County, and lime is produced also near
West Chester in this county. Lime is manufactured at Swatara Station
and Paxtang, Dauphin County and at Billmeyer and other localities in

CRUSHED AND BROKEN LIMESTONE 437

Lancaster County. A high-grade bed of Hmestone in the Lebanon Valley,
Lebanon County, supplies stone for lime plants at Annville, Myerstown,
and Lebanon. Several important lime plants are located near York and
Thomasville, York County, and near Bridgeport and Plymouth Meeting,
Montgomery County. A small output is reported from Cumberland,
Franklin, Northampton, and Perry Counties.

Centre County in central Pennsylvania is the most productive
county in the State having several large well-equipped plants near
Bellefonte and Pleasant Gap. Most of the raw material is obtained
from a bed of very pure high-calcium stone approximately 80 feet thick
dipping at a steep angle. A very large underground mine supplies stone
to one plant near Bellefonte. Other lime plants in the central area are
located at Naginey, Mifflin County; and at Jersey Shore, Muncy, and
Williamsport, in southern Lycoming County. Smaller plants operate in
Blair, Huntingdon, Juniata, Snyder, and Union Counties. In east-
central Pennsylvania lime is burned at Bloomsburg and other points in
Columbia County, at Danville and several other places in Montour
County, and in Northumberland County.

Bedford County, in southwestern Pennsylvania, is an active producer,
with plants at Everett, New Enterprise, and seven or eight other localities.
Quite a number of small plants operate in Somerset and Westmoreland
Counties.

No large lime plants are situated in western Pennsylvania. Lime
is burned at Branchton, Butler County; at Reynoldsville, Jefferson
County; and at Rose Point, Lawrence County. Smaller plants operate
at other points in the above and in Armstrong and Indiana Counties.

Crushed-stone Industry. — As over 200 quarries produce crushed lime-
stone in Pennsylvania, reference necessarily is confined to the chief
production centers. The most active producing districts are in south-
eastern and central Pennsylvania, though there are several very large
mines and quarries in the western part of the State. Unless otherwise
noted, the quarried stone is used for concrete aggregate or as road
material.

Southeastern District. — Quarries are operated at Springtown and other
points in Bucks County. Montgomery County is an important source
of dolomite. The principal quarries are at Bridgeport, Conshohocken,
Plymouth Meeting, Norristown, and Ambler. Although large quantities
are used for ordinary crushed-stone purposes, substantial quantities are
employed as a refractory in steel furnaces and as a raw material for
magnesia for "85 per cent magnesia" pipe covering. Stone from one
quarry at Bridgeport is pulverized and sold as filler in rubber, asphalt,
and other products. Very extensive dolomite quarries are worked at
Devault, Berwyn, Malvern, West Chester, and Howellville, Chester
County, part of the product being used as a source of magnesia for pipe

438 THE STONE INDUSTRIES

covering, for filler, and as agricultural limestone. West of Hanover,
Adams County, high-calcium limestone is quarried very extensively
for furnace flux, as well as for road stone and concrete aggregate.

York County is a very important producer of limestone. One large
quarry near York supplies great quantities of fluxing stone and several
produce road stone, concrete aggregate, stone for refractory uses, and
pulverized stone for filler. A large quarry at Thomasville produces
stone for furnace flux, glass and paper mills, and agricultural purposes.
Scores of quarries operate in the high-grade limestone beds of Lancaster
County. The largest of these, at Bainbridge, produces stone for iron
furnaces and paper mills, as well as for ordinary crushed-stone products.
Other important quarries are at Rheems, Lancaster, Columbia, East
Petersburg, Blue Ball, Quarryville, West Manheim, Mount Joy, Bare-
ville, and Ephrata. Several large quarries are worked in Berks County,
notably at Shillington, South Temple, Reading, West Leesport, and
Wernersville. Large quarries at and near Allentown supply that popu-
lous center in Lehigh County, and limestone is quarried also at other
points. Northampton, Nazareth, Easton and Bethlehem are the
chief quarry centers of Northampton County; the Bethlehem quarries
supply large quantities of fluxing stone for the iron and steel industry
of that city.

A belt of high-calcium limestone passing through Lebanon County
is worked in several places, though quarrying is difficult owing to an
excessive flow of water. Much stone from this area is used by cement
plants in Lehigh and Northampton Counties to raise the calcium car-
bonate content of the cement rock. Fluxing stone and agricultural
limestone are other important products. The chief quarry centers are
Annville, Lebanon, Donaghmore, Myerstown, and Palmyra.

The largest quarry in Dauphin County is at Steelton. The principal
product is fluxing stone for use in furnaces located near the quarry.
A large modern crushing plant was recently built. Fluxing stone is
obtained also at Swatara Station. A new crushing plant of modern
design serves a large quarry near Harrisburg. Paxtang, High Spire,
Hummelstown, and Hershey are other limestone-quarry centers in this
county. Crushed stone is produced near Bloomsburg, Columbia County;
and at Mausdale, Montour County.

Cumberland County is an active producer, with quarries at Carlisle,
Camp Hill, Lemoyne, Shippensburg, and Newville. In Franklin County
large quarries operate at Williamson, Waynesboro, and Chambersburg
and quite a number of smaller ones at various points. Limestone
for road construction is quarried at Landisburg and Blain, Perry
County.

Central District. — Canister, Blair County, is an important center of
production of fluxing limestone. Crushed limestone is produced also

CRUSHED AND BROKEN LIMESTONE 439

at Canoe Creek, Frankstown, Duncans vi lie, Roaring Spring, and Tyrone
in this county.

An important limestone in Centre County is suitable for a variety of
uses, and large quantities are quarried for furnace flux, coal-mine dusting,
glass factories, and agriculture in addition to that devoted to the more
common uses, such as concrete aggregate and road building. The
principal quarries are near Bellefonte, Oak Hall Station, State College,
and Pleasant Gap.

A quarry at Salona, Clinton County, produces concrete aggregate,
road stone, and railroad ballast. Large quarries are worked at Union
Furnace, Mapleton Depot, and Orbisonia, Huntingdon County; and at
Naginey, Mifflin County. One of the Naginey quarries has been devel-
oped recently and is well-equipped to produce great quantities of fluxing
stone for use in open-hearth steel furnaces. Crushed stone is produced
at Jersey Shore, Muncy, and Chippewa, Lycoming County, and at
various points in Snyder and Union Counties.

Southwestern and Western Districts. — Ashcom, Hyndman, and Water-
side are the principal quarry centers of Bedford County. A great many
small quarries, most of them now inactive, are to be found in many parts
of Westmoreland County. Road stone is quarried at several places in
Somerset County, chiefly at Garrett.

High-grade deposits of Vanport limestone in several western counties
have great economic value because of their proximity to the extensive
iron and steel industries of the Pittsburgh district. Most of them,
however, have the disadvantage of a very heavy overburden; in conse-
quence, large underground mines have been developed. What is
probably the largest limestone mine in the country, capable of producing
3,500 tons of stone a day, is operated at Kaylor, Armstrong County.
Other mines in this county for production of fluxing stone are located at
Worthington, Kittanning, and Templeton. In Butler County very
extensive mines whose chief product is fluxing stone are located at
Annandale, Osborne, Branchton, and West Winfield.

Enormous quantities of limestone are produced in Lawrence County.
One underground mine is worked near Ellwood City, but the great bulk
of production is from a series of large open pits near Hillsville. During
a normal year between 2 and 3 million tons of fluxing stone, with sub-
stantial supplies of crushed stone for concrete aggregate, road building,
and agricultural limestone, are produced in this district. A large open
quarry is worked at Rose Point. Road stone is produced near Clarion,
Clarion County.

Rhode Island. — Commercial limestone occurrences in Rhode Island
are confined to the vicinity of Lime Rock, Providence County, in the
northern part of the State. The stone is used principally for lime manu-
facture in one lime plant, with a minor production of stone for furnace

440 THE STONE INDUSTRIES

flux and other uses. The lime may be classed as low-magnesian, a typical
analysis of the stone showing about 9 per cent magnesium carbonate.
Limestone beds occurring in other parts of the State are too small to have
economic importance.

South Carolina. — Metamorphosed limestone or marble occurs in
western South Carolina and soft Tertiary limestones or marls on the
Coastal Plain. Most of them are high in silica but might prove satis-
factory for cement manufacture. No cement has yet been made in the
State. Crushed Hmestone is produced at Gaffney, Cherokee County, and
agricultural limestone at Saint Matthews, Calhoun County.

South Dakota. — ^Limestones occur in the Black Hills district of west-
ern South Dakota and in the eastern part of the State. The Black
Hills uplift of crystalline rocks brought with it a series of Paleozoic and
Mesozoic sediments which dip outward toward the plains. Limestones
of various ages appear where the upturned strata have been partly eroded
away. The more important are the Englewood and Pahasapa, of Mis-
sissippian (Lower Carboniferous) age, and the Minnekahta, of Pennsyl-
vanian (Upper Carboniferous) age. The latter contains considerable
magnesium. The Niobrara (Cretaceous) chalk underlying most of
South Dakota averages about 150 feet in thickness. It appears most
prominently in the southeastern part of the State, where it outcrops in
many places along the Missouri River from Yankton to Fort Thompson
and in the James River Valley.

Limestone quarries are confined almost exclusively to the Black Hills
district. The State has one cement plant, at Rapid City, Pennington
County. Recent production of lime has been confined to plants in
Pennington County near Rapid City, but lime is produced at times in
Custer, Lawrence, and Meade Counties. The largest quarries for
production of crushed stone are near Rapid City, Pennington County.
The products are concrete aggregate, road stone, and limestone for sugar
mills. Smaller quarries are operated in Custer, Lawrence, and Fall
River Counties. Except for small local quarries in southeastern counties
the Niobrara chalk has no commercial use at present.

Tennessee. — ^Limestones abound in Tennessee, particularly in the
eastern and central regions. The most important of the oldest (Cam-
brian) limestones is the Knox dolomite, although the upper part of the
Knox is classed as Ordovician. East of the valley of the Tennessee
River, which passes through Knoxville, Ordovician limestones are plenti-
ful. The lowest bed is the Chickamauga, part of which is argillaceous;
but the part known as the Holston formation is a very pure, high-grade,
crystalline rock that has made Knoxville famous as a marble center.
Other limestones occur at higher levels, but most of them are impure.
On the western side of this valley Chickamauga limestones, 1,200 to

CRUSHED AND BROKEN LIMESTONE 441

2,000 feet thick, occur in great abundance. Some parts of the formation
are pure, while other beds are argillaceous.

The lowest available limestones of middle Tennessee are those of
the Stones River group, of Ordovician age. The Murfreesboro is the
lowest member, and following in order are the Pierce, Ridley, Lebanon,
and Carters. They consist of pure to argillaceous limestones, most of
which are low in magnesium. The Carters, which occurs in most of the
counties of the central basin, is widely used for lime burning. Lime-
stones, of Trenton age, many of which are argillaceous, form an irregular
belt which entirely encircles those of the Stones River group. Above
the Trenton are the Cincinnatian (Upper Ordovician) and the Silurian
and Devonian limestones; the latter occur prominently in middle, west-
middle, and northern Tennessee. Like the Trenton rocks, many of them
contain considerable clay and shale. The Mississippian (Carboniferous)
formation, which occurrs most prominently in the northern and western
counties of middle Tennessee, contains high-grade limestone in places.

The total value at the plant of limestone and its principal primary
products (cement and lime) produced in Tennessee in 1929 approached
$9,000,000, and in 1937, approximately $7,900,000. Cement plants,
lime kilns, and quarries for production of raw limestone are widely
scattered throughout the eastern and central areas. Recent additions
of cement plants, raising the total of the State to six, has made Tennes-
see an important producer, with normal annual value of cement reaching
5)4 to 63-^ million dollars.

In eastern Tennessee two cement plants are in operation. One of
the long-established mills at Kingsport, Sullivan County, is supplied
with limestone from a quarry at Speer's Ferry, Va. A plant at Caswells
Station east of Knoxville, Knox County, uses the Holston marble as its
calcareous raw material. Mississippian beds furnish limestone to one
of the newer cement plants at the base of Signal Mountain near Chat-
tanooga, Hamilton County. A short distance west, at Richard City,
Marion County, is the oldest plant of the State; it was first operated in
1907. Other plants are located at Cowan, Franklin County, and at
Nashville, Davidson County; the latter plant uses Ordovician limestone.

Knox County produces the most lime; the pure high-calcium Holston
marble supplies raw material for several plants near Knoxville. All
the other important lime plants are in central Tennessee. Lime is
manufactured at Crab Orchard, Cumberland County; and at Summit-
ville, Coffee County. The largest plant in the State (at Sherwood,
Franklin County) is equipped with both rotary and shaft kilns. Other
lime-producing centers are Watauga, Carter County; Burns, Dickson
County; Erin, Houston County; Palmyra, Montgomery County; and
Columbia, Maury County.

442 THE STONE INDUSTRIES

The crushed-limestone industry extends throughout the same general
territory as the lime and cement industries, namely, the eastern and
central counties. Stone is quarried for concrete aggregate and road
building at Bristol, Kingsport, and other points in Sullivan County near
the eastern tip of the State; road stone at Johnson City, Washington
County; and furnace flux near Milligan College and Watauga, Carter
County. The largest quarries are in Knox County near Mascot and
Strawberry Plains. Many thousand tons of railroad ballast, concrete
aggregate, and road stone are produced, as well as large supplies of
roofing gravel, asphalt filler, and agricultural limestone. Stone for
railroad ballast and other uses is quarried at Crab Orchard, Cumberland
County. Another large quarry is located at Harriman, Roane County,
and smaller ones in Blount, Loudon, and Campbell Counties. Quarries
are worked in Coffee, Rutherford, Marshall, and White Counties in
central Tennessee. Limestone quarried at Sparta in the latter county
is pulverized and sold as filler. Crushed limestone is produced at Sher-
wood, Franklin County, and at East Chattanooga and other points in
Hamilton County. Antioch and Nashville, Davidson County, and
Franklin, Williamson County, are important quarry regions in western-
central Tennessee. Impure limestone quarried at Rockdale, Maury
County, is used for the manufacture of mineral wool. Crushed stone is
obtained at Clarksville, Montgomery County, and in Wilson County,
while fluxing stone is quarried in Hickman County.

Texas. — ^Limestones are distributed widely in Texas, particularly in
the eastern half of the State. The Ellenburger limestone, of Cambro-
Ordovician age, occurring in east-central Texas, is a hard, light-colored
rock recrystallized to marble in places. Carboniferous and older Palae-
ozoic rocks occurring in the north-central region are used to a limited
extent.

The most important limestones for cement, lime, and crushed-stone
uses are of Cretaceous age. The Austin Chalk, which is of especial
importance as a cement-making material, occurs in a well-defined belt
in east-central Texas. From Red River in the northeastern part of the
State it extends westward near Clarksville, Honeygrove, Paris, and
Sherman. From Sherman it extends south and southwest beneath
Dallas, Waco, Austin, and San Antonio, terminating a little southwest of
the last city. It is 400 to at least 600 feet thick and in many places
remarkably uniform. Analyses show a calcium carbonate content of
70 to more than 90 per cent and very little magnesium. It occurs in the
most populous part of Texas, and quarry conditions are favorable.

The Fredericksburg group of Lower Cretaceous Age outcrops west of
the Austin Chalk. There are three important members — the Goodland
at the north, and the Edwards and the Comanche Peak to the south.
The limestones of this group occur in large areas in Wise, Parker, Hood,

CRUSHED AND BROKEN LIMESTONE 443

Erath, Bosque, Hamilton, Coryell, Lampasas, Burnet, Blanco, Kendall,
Comal, and Bexar Counties. Still larger areas are exposed in the
Edwards Plateau west of San Antonio. Ordovician, Silurian, Carbon-
iferous, and Cretaceous limestones occur in western Texas near El Paso.
The Ordovician is used for lime and the Lower Cretaceous for the manu-
facture of cement and fluxing stone.

With 9 or 10 plants normally in operation and a production value of
nearly $12,000,000 in 1929 and $11,490,000 in 1937, Texas is an important
producer of cement. In the former year the Hme output was valued
at more than $838,000, and limestone sold in the raw state in crushed
and broken form at about $2,300,000. Corresponding figures for 1937
were $440,000 and about $1,397,000.

Most Texas cement plants are on the Cretaceous belt. Two near
Dallas, Dallas County, one at Waco, McLennan County, and two near
San Antonio, Bexar County, use the Austin Chalk, and a plant at Fort
Worth, Tarrant County, Lower Cretaceous limestone. Three cement
plants operate near Houston, Harris County; one utilizes oyster shells
as calcareous raw material. A plant at El Paso, El Paso County,
western Texas, is supplied with limestone from Lower Cretaceous beds.

The lime industry of western Texas is confined to a group of plants
near El Paso, El Paso County. A plant first operated in 1929 near
Houston, Harris County, employs a gas-fired rotary kiln to calcine
oyster shells into lime. The other lime plants of the State are in the
east-central district. The largest are at New Braunfels, Comal County;
McNeil, Travis County; and Round Rock, Williamson County. Lime
is also produced at Lime City near Oglesby, Coryell County; and, accord-
ing to report, a new plant was built at Big Spring, Howard County, in
1931.

Except for large quarries at El Paso producing concrete aggregate,
road stone, and smaller quantities of furnace flux, practically all of the
crushed-limestone plants are in the east-central area. In the north-
central district large quarries are worked at Jacksboro, Jack County;
Bridgeport and Chico, Wise County; Salesville, Palo Pinto County;
and in Shakelford and Jones Counties. The products are road stone and
concrete aggregate, with a smaller output of railroad ballast. Farther
south large operations are conducted at Tiffin, Eastland County, chiefly
for railroad ballast, with smaller quantities of concrete aggregate, road
stone, and riprap. Ballast is produced in Brown County, and large
quantities of both ballast and road stone are quarried at Richland,
Navarro County. The largest establishment in southern Texas is at
New Braunfels, Comal County, where many thousands of tons of con-
crete aggregate, road stone, and railroad ballast are produced. San
Antonio, Bexar County, is another important center, where several
quarries produce crushed stone, road base, ballast, and stone for filter

444 THE STONE INDUSTRIES

beds. Road material is quarried in Milam County and also in Sutton
County farther west.

A coarse-grained, asphalt-bearing limestone of Upper Cretaceous Age,
associated with igneous intrusions, is quarried extensively near Uvalde,
Uvalde County, and in Kinney County. Average rock consists of 10 to
12 per cent asphalt and 88 to 90 per cent limestone, a proportion which
gives very satisfactory road-building material. The stone, shattered
with dynamite, is loaded by steam shovels into standard-gage railroad
cars and hauled to a central crushing plant, where it is crushed, pulverized,
screened, and blended with asphaltic flux oil. It is claimed that 1 ton of
stone will cover 20 square yards of pavement 1 inch thick. It is produced
on a large scale and has been used in surfacing hundreds of miles of
highways, chiefly in Bexar County.

Utah. — The most important limestones of Utah are those of Carbon-
iferous age, which occur in many parts of the Wasatch Mountains in the
northern and north-central counties. Many of the deposits are argil-
laceous, a condition which is not detrimental for cement manufacture
but is undesirable for most other uses. However, quite a number of
occurrences are pure enough for the manufacture of lime and for use in
sugar mills. Softer limestones, of Eocene age, occur in the Plateau
district. Marl deposits in an ancient bed of Great Salt Lake are also
available.

Although Utah has some important cement and lime industries, lime-
stones have not been utilized extensively in other ways. Quarries
are confined almost exclusively to the northern and north-central regions.

The oldest cement plant of the State is at Salt Lake City, Salt Lake
County. Its calcareous raw material is obtained from limestone beds,
probably of Carboniferous age, at Parley's Canyon several miles south-
east of the city. Another large plant at Devils Slide, Morgan County,
also employs Carboniferous limestone. A cement plant built at a later
date at Bakers, Box Elder County, is supplied with marl and underlying
clay from an abandoned bed of Great Salt Lake.

The largest output of lime in the State is in Salt Lake County, where
one large and several smaller plants produce it for building and for
metallurgical use in the important smelters and ore-treatment plants
of Salt Lake City. A plant at Garfield is unique in that it utilizes
limestone sand as raw material. Lime is made also at Logan, Cache
County; near Ogden, Weber County; at Grantsville, Tooele County;
and in the southwest corner of Utah County near Eureka. A small plant
near Salina, Sevier County, produces lime for building and for sugar
manufacture. A small output is reported from Cedar City, Iron County,
near the southwestern corner of the State.

The crushed-limestone industry of Utah is relatively small and is
peculiar in that very little of the product is used for the more common

CRUSHED AND BROKEN LIMESTONE 445

applications, namely, as road stone or concrete aggregate. At Lucin and
Lakeside, Box Elder County, considerable quantities of railroad ballast
are produced as occasion demands. The chief production is at Topliff,
Grants ville, and other points in Tooele County, to provide stone for
furnace flux and, in smaller quantities, for sugar mills. Fluxing stone is
produced also in Salt Lake County, and pulverized stone for coal-mine
dusting at Devils Slide, Morgan County. Limestone is furnished to sugar
factories from quarries in Cache, Sevier, Salt Lake, and Utah Counties,
and for use as poultry grit in the last two counties.

Vermont. — The calcareous rocks of Vermont are of two distinct types.
Marbles occurring abundantly in the Champlain Valley, passing through
Brandon, Rutland, and Dorset, have been described in some detail in the
chapter devoted to the marble industry. The second type comprises
the noncrystalline limestones of Ordovician age (Chazy and Trenton),
occurring principally in the northwestern counties, Addison, Chittenden,
and Franklin. Most of the marbles are very pure and low in magnesium.
The limestones are more variable in composition, but most of them
contain only a small amount of magnesium.

Suitable stone for cement manufacture is obtainable in Vermont,
but an industry has not been established because the State is handicapped
by limited local markets and high-priced fuel.

The largest lime plant, at West Rutland, Rutland County, uses waste
marble, which is very abundant in this region. It is calcined in a rotary
kiln. Moderate-sized lime plants operate at Fonda Junction, St. Albans,
and Swanton, Franklin County; Winooski, Chittenden County; Leicester
Junction and New Haven Junction, Addison County; and Amsden,
Windsor County.

Crushed-limestone production is small, and much of it consists of
by-products at lime plants. Road stone and concrete aggregate are
produced in limited quantities at Swanton, Franklin County, and near
Burlington, Chittenden County. Agricultural limestone is, or has been,
ground at Winooski in the latter county and in Bennington County.
Terrazzo chips are manufactured from waste marble at West Rutland and
Brandon, Rutland County, and at Middlebury, Addison County. Road
stone and agricultural limestone are also produced in the latter county
and a small quantity of agricultural limestone in Windham and Windsor
Counties.

Virginia. — The famous Shenandoah Valley and similar valleys lying
northwest of the Blue Ridge Mountains contain the valuable Virginia
limestones. The most important members are the Shady dolomite, of
Cambrian age, and the Lenoir, Mosheim, and Holston limestones, of
Ordovician age. The Mosheim is the highest grade limestone of the
state and is practically continuous from Maryland to Tennessee and
beyond. Limestones of these formations have great commercial value in

446 THE, STONE INDUSTRIES

the two western tiers of counties throughout the entire length of the State,
except Buchanan and Dickenson Counties, which are west of the valley
region.

Helderberg (Devonian) limestone occurs in the Alleghany Mountains.
It is quite variable in composition but has been found satisfactory for
cement manufacture in Augusta County. Greenbrier and Newman
limestones, of Mississippian age, occur in narrow bands in the south-
western corner of the State, beds of maximum thickness appearing near
Cumberland Gap at the Tennessee border.

Tertiary shell beds or shell marls occur in the eastern Coastal Plain
district, chiefly in Norfolk, Nansemond, Isle of Wight, Surry, York, and
Gloucester Counties. They consist of shells of various molluscs mixed
with sand and clay. They have little practical value, except for manu-
facture of cement.

The limestone industries of Virginia have considerable importance.
The value of the output of cement is unrecorded because of the small
number of plants. Lime sold in 1929 was valued at over $1,000,000 and
the production of crushed limestone at nearly $2,500,000. Correspond-
ing figures for 1937 were $1,248,479 and $3,016,899.

Virginia has two cement plants. One, which uses Tertiary shell
deposits as raw material, is favorably situated at South Norfolk, Norfolk
County. The second plant, using the Helderberg limestone, is at
Fordwick, Augusta County.

Over 30 lime plants are normally in operation, nearly all of them in
the Appalachian Valley in the western part of the State. One of the
few producing districts in the Piedmont east of the Blue Ridge is at
Leesburg, Loudoun County. The largest plants in the State are at
Stephens City, Frederick County; and at Riverton, Warren County.
Other important lime plants in the northwestern area are at Limeton,
Warren County; and at Oranda, Strasburg, Strasburg Junction, and
Toms Brook, Shenandoah County. In the west-central area lime plants
operate at Linville and Bridgewater, Rockingham County; several small
plants are located at Staunton and other points in Augusta County;
and three large plants, one at Indian Rock and two at Eagle Rock, are
located in Botetourt County. In the southwestern part of the State
lime plants are located at Kerns and Ripplemead, Giles County; and at
Maxwell, Richlands, and Tazewell, Tazewell County. A small output is
reported at times from Montgomery County.

Crushed limestone is produced in large quantities in Virginia and is
applied to a great variety of uses. In the northwestern area road stone
and concrete aggregate are produced at Leesburg, Loudoun County; and
the same products, with fluxing stone and agricultural limestone, are
prepared at Stephens City and Winchester, Frederick County. Railway
ballast and other forms of crushed stone are produced at Riverton and

CRUSHED AND BROKEN LIMESTONE 447

Limeton, Warren County, as by-products of lime industries. Large
quantities of road stone have recently been quarried at Strasburg, Toms
Brook, Mount Jackson, and New Market, Shenandoah County, mainly
for improvement of the famous Shenandoah Valley pike.

In the west-central area quarries for the production of road stone
and aggregate are maintained at Harrisonburg and other parts of Rock-
ingham County; at Waynesboro, Staunton, New Hope, and other
points, in Augusta County; and at Hot Springs, Bath County. Crushed
stone for railroad ballast and other uses is produced in Rockbridge
County. Agricultural limestone and fertilizer filler are the chief products
of quarries near Falling Springs, Alleghany County. Many thousand
tons of road stone and railroad ballast are produced at Blue Ridge and
Rocky Point, Botetourt County, and quarries at the latter place produce
stone also for furnace flux, paper mills, agricultural use, asphalt filler,
and for coal-mine dusting. Road stone is quarried near Bonsacks, and
both flux and road stone are sold as by-products of lime industries
situated near Buchanan and at Eagle Rock.

In southwestern Virginia large quarries are worked for road stone and
ballast production near Roanoke, Roanoke County; near East Radford,
Pulaski County; and at Pembroke and Ripplemead, Giles County.
Stone for carbide manufacture is produced near Kerns, Giles County. A
large quarry at Ivanhoe, Wythe County, at times provides limestone for
calcium carbide manufacture, and agricultural limestone is produced at
Austinville. Fluxing stone is obtained at Pulaski. Agricultural lime-
stone and road stone are other important products of Pulasli County.
One of the largest quarries in the State supplies stone for alkali manu-
facture at Saltville, Smyth County, while quarries at Marion and other
points produce ballast and road stone. Other important limestone-
quarry centers in the southwest are at Pounding Mill, Tazewell County;
and Wheeler, Lee County. Quarries are also operated in Russell,
Washington, Wise, and Scott Counties. A quarry at Speer's Ferry, Scott
County, supplies limestone to a large cement plant at Kingsport, Tenn.

Washington. — Northwestern Washington has the distinction of
possessing the only extensive limestone deposits on deep water along the
Pacific coast of the United States. The more important of the coast
deposits are the highly crystalline limestones, of Devonian, Carbonifer-
ous, and Triassic ages, on San Juan and Orcas Islands. On San Juan
Island they outcrop in heavy beds, reaching a height of 200 feet above
tidewater. Similar crystalline limestones occur near Kendall, Whatcom
County; near Granite Falls, Snohomish County; and in eastern King
County. They also outcrop in various parts of northern and north-
eastern counties near the British Columbia boundary. The north-
eastern limestones range in age from possible pre-Cambrian to
Carboniferous.

448 THE STONE INDUSTRIES

As six plants normally are in operation in Washington the manu-
facture of cement is an important industry, but the lime and limestone
industries are relatively small. Crushed-limestone products sold in 1929
were valued at about $130,000 and the lime output at about $325,000.
Figures for cement are not available.

Four of the six cement plants are in western counties, and two are
close to the eastern border of the State. A plant at Bellingham, What-
com County, uses crystalline limestone quarried at Balfour 35 miles
away. Marketing of the product is favored by availability of water
transportation. A mill at Concrete, Skagit County, is supplied with
limestone quarried about 2 miles away and brought to the plant by aerial
tramway. A cement mill at Seattle, King County, is unusual in that its
limestone supplies are shipped by water from Dall Island, Alaska,
about 700 miles. A plant at Grotto, in northeastern King County, uses
local limestone. A cement mill that has operated for many years at
Metaline Falls, Pend Oreille County, near the northeastern corner of the
State uses crystalline limestone occuring near the plant. Limestone
supplies for a cement mill at Spokane, Spokane County, are shipped by
rail from a quarry at Lakeview, Idaho.

The lime industry of Washington is confined to the northwestern
and northeastern corners of the State. There are several plants at
Roche Harbor, Friday Harbor, and other points on Orcas and San Juan

Islands, San Juan County. The crystalline limestones of these islands
calcine to a very pure lime, and availability of water transportation is an
added asset. Lime is manufactured near Bossburg, Stevens County,
from high-calcium marble. Dolomite calcined at Colville in this county
is used in paper manufacture.

Relatively small amounts of crushed limestone are produced in
Washington and very little of it is used, except locally, for road stone or
concrete aggregate. The crystalline limestones of San Juan County are
quarried to supply paper mills, glass factories, and sugar refineries
and for manufacture of furnace flux and poultry grit. The limestones or
marbles quarried in northern Stevens County are sold chiefly to paper
mills or as furnace flux, with smaller amounts for agriculture, poultry
grit, terrazzo, and coal-mine dusting.

West Virginia. — The more important limestones of West Virginia
occur in Jefferson and Berkeley Counties by virtue of the fact that they
intersect the Shenandoah Valley, which is traversed by a broad belt of
rock known formerly as the Shenandoah limestone; its important mem-
bers are the Shady dolomite, of Cambrian age, and the Mosheim lime-
stone of Ordovician age. One member of the Shenandoah group —
the Stones River of Ordovician age — furnishes high-quality limestone
which is particularly well-developed in the northeastern counties of
West Virginia. The rock is admirably suited for furnace flux, chemical

CRUSHED AND BROKEN LIMESTONE 449

uses, and cement manufacture. Other members of the Shenandoah
formation provide high-grade dolomites that are utihzed extensively for
basic refractories. A detailed description of the limestones in this area
has been published.®*

Other limestones, of Cambrian, Ordovician, Silurian, Devonian, and
Mississippian ages, outcrop in the folded territory of other eastern and
southeastern counties, but few approach in purity those of the north-
eastern Panhandle region. Some are of high quality, for use in crushed
form as concrete aggregate, road stone, or railroad ballast, and are
quarried for such purposes, particularly in Greenbrier, Pocahontas,
Preston, and Monongalia Counties. They also provide raw material
for cement manufacture in Preston County.

The limestone industries of West Virginia are of considerable mag-
nitude. Three cement plants are in operation, but figures for value
of production are not available. Normally about a dozen lime plants are
active, their output being valued at more than $1,800,000 in 1929
and $1,617,040 in 1937. Crushed and broken limestone produced was
valued at nearly $3,000^000 in 1929 and more. than $2,450,000 in 1937.

A cement plant at Martinsburg, Berkeley County, employs Shenan-
doah limestone as its calcareous raw material, A second plant, at
Manheim, Preston County, is provided with limestone from large, care-
fully planned underground workings. The third cement mill of the
State, at Kenova, Wayne County, is supplied with limestone quarried
at Lawton, Ky.

All the larger lime plants of West Virginia are in the northeastern
Panhandle district, where high-grade Stones River limestone is available.
Chief centers of production are near Martinsburg and Berkeley, Berkeley
County; and at Bakerton and Millville, Jefferson County. A high-
grade dolomite occurring near Millville in the latter county is quarried
extensively for manufacture of refractory dead-burned dolomite. Lime
is manufactured at Terra Alta, Preston County, and small kilns are
located at several other places in that county. Lime and dead-burned
dolomite are manufactured at Kenova, Wayne County, from dolomite
shipped to the kilns from quarries at Peebles, Ohio.

Aside from that used in the manufacture of cement and lime, nearly
two thirds of the crushed and broken limestone of West Virginia is sold
as furnace flux. The most important production centers are Falling
Waters and Martinsburg, Berkeley County; and Millville and Engle,
Jefferson County. Most of the furnace flux is used in the Pittsburgh
(Pa.) district. Crushed stone produced at most of the above locations
and also at Berkeley is sold as railroad ballast, concrete aggregate, and
road stone ; for glass manufacture ; and in pulverized form, as agricultural

^' Grimsley, G. P., Jefferson, Berkeley, and Morgan Counties. West Virginia
Geol. Survey, 1916, pp. 361-583.

450 THE STONE INDUSTRIES

limestone and asphalt filler. Large quantities of ballast, concrete aggre-
gate, and road stone are produced at Fort Spring, Renick, and near
Frazier, Greenbrier County. Other quarries for production of crushed
stone or agricultural limestone are operated at Greer, Monongalia
County; and at Wheeling and other points in Ohio County. Many
small quarries have been worked in Preston County, but most of them
are now inactive.

Wisconsin. — Pre-Cambrian rocks, which are enveloped by suc-
ceeding belts of Paleozoic sediments, occupy the north-central and
northern sections of Wisconsin. Limestones appear in a broad belt
along the eastern side of the State, extend across the southern part, and
are available in certain areas along the western side. They dip in a
general way toward the nearest boundary of the State. The principal
formations are the Lower Magnesian, Platteville (Trenton), and Galena,
of Ordovician age, and the Niagara, of Silurian age. A small occurrence
of limestone, younger than the Niagara, appears north of Milwaukee.
Like those of Minnesota, the limestones of Wisconsin are of the high-
magnesian type, and nearly all of them are dolomites. They are
unsuited for cement manufacture but are well adapted for making high-
magnesian and special limes, and for many uses in crushed, broken,
or pulverized form.

The output of cement in the State is small, but other limestone
products are manufactured in large quantities. Eighteen or twenty lime
plants are operated in times of normal business activity. Their produc-
tion was valued at more than $1,000,000 in 1929 and at $508,536 in 1937.
In the number of active limestone quarries within its borders Wisconsin
is exceeded only by Pennsylvania and Ohio. The value at the quarry of
crushed and broken limestone sold in 1929 exceeded $3,800,000, and in
1937, $2,338,000.

The only cement plant in the State is operated at Manitowoc, Mani-
towoc County. As all the limestones in this territory are dolomitic,
supplies of calcareous raw materials are obtained from a Michigan Lake
port. A cement-packing plant is maintained at Milwaukee.

The lime industry is confined to the east-central counties. Plants
are operated near Green Bay, Brown County, from limestone shipped
from Michigan. It is also manufactured at Brillion, Hayton, and High-
cliff, Calumet County. Manitowoc County is an important center of
production. Special grades of high-magnesian lime produced at Francis
Creek near Manitowoc are sold for polishing and buffing. Plants are
operated also at Grimms, Quarry, and Valders. Sheboygan, Sheboy-
gan County; Eden, Fond duLac County; Nasbro, Mayville, and Knowles,
Dodge County; and Cedarburg, Ozaukee County; are other important
centers of high-magnesian lime production.

CRUSHED AND BROKEN LIMESTONE 451

Crushed limestone is produced principally in the eastern and south-
eastern sections. The most northerly, as well as the largest quarry in
the State, is at Sturgeon Bay, Door County. Quarries are operated also
at Green Bay, Duck Creek and other points in Brown County; at Kau-
kauna, Outagamie County; at Oshkosh and Menasha, Winnebago
County; at Highcliff, Hayton and Brillion, Calumet County; and at
Grimms, Quarry, Valders and Manitowoc, Manitowoc County. Lime-
stone is quarried at Eden, Oak Center, Ripon, and Hamilton, Fond du
Lac County; and in conjunction with lime manufacture at Sheboygan,
Sheboygan County. Quarries are in operation at Nasbro and Mayville,
Dodge County, and at Cedarburg and other points in Ozaukee County.
The chief production in Waukesha County is centered near Waukesha.
The main product is crushed stone for road work and concrete aggregate ;
smaller amounts are employed as flux, agricultural limestone, asphalt
filler, and poultry grit. Other important quarries are at Lannon, where
riprap and crushed stone are produced. Large quarries at Wauwatosa,
and Milwaukee, Milwaukee County, supply that populous region, and
even larger operations are conducted near Racine, Racine County, near
the southeastern corner of the State. By far the largest proportion of all
limestone quarried in the eastern area is for road construction and con-
crete aggregate, with smaller amounts for furnace flux, agricultural
limestone, railroad ballast, stucco, and riprap.

Other important limestone centers, though comprising a less-pro-
ductive area than the eastern, are scattered throughout western and
southwestern counties, principally along the Mississippi River. Crushed
stone is produced at Wilson, St. Croix County; in Buffalo County; and
at Elmwood, Pierce County. Agricultural limestone is an important
supplementary product of the latter region. Road stone and concrete
aggregate are produced at La Crosse and other places in La Crosse
County; in Sauk County; and at Hillsboro, La Farge, Springville, and
other points in Vernon County. Riprap for shore protection along the
Mississippi River is an important product of the last county. Many
quarries for production of crushed stone are operated in Grant County
in the southwest corner of the State, at Fennimore, Blue River, Cassville,
Lancaster, Kieler, Bloomington, Mount Hope, Wyalusing, and other
points. Lafayette and Green Counties at the southern border record an
output of crushed limestone for large highway construction projects.
Many small local quarries having an aggregate production of considerable
magnitude produce highway-surfacing limestone in Richland, Iowa,
and Crawford Counties.

Wyoming. — Limestones are found in many parts of Wyoming but
have not been developed extensively. The best-known deposits are in
Albany, Laramie, and Platte Counties in the southeast and in Weston

452 . THE STONE INDUSTRIES

County in the northeast. Most of them are of the high-calcium type,
and many deposits low in impurities are available.

No lime has been made in Wyoming during recent years, but the State
has one cement plant. Aside from that used for cement, more than 80
per cent of the limestone quarried in Wyoming is used in beet-sugar
manufacture. Limestone sold was valued at about $475,000 at the
quarries in 1929 and at $317,000 in 1932.

A cement plant began operation at Laramie, Albany County, in 1929.
Its limestone supply is obtained from Niobrara (Cretaceous) beds 9 miles
west of the mill.

One of the largest quarries in the country to supply limestone for sugar
factories is at Horse Creek, Laramie County. The same product is
obtained at Granite Canon and other points in this county. Stone to
supply sugar factories is obtained in substantial quantities at Guernsey
and Hartville, Platte County, and this county is also a source of road
stone and riprap in small amount.

QUARRY METHODS AND EQUIPMENT

Preliminary Steps. — Establishment of the quality and quantity of
limestone available in a deposit is an important preliminary step. Meth-
ods of rock exploration and removal of overburden from the rock sur-
face, have already been described in the chapter on prospecting and
development.

Plan of Quarry. — Limestone is a sedimentary rock deposited in suc-
cessive horizontal layers or strata. In some important quarry regions,
particularly throughout the Middle West, the original beds are prac-
tically undisturbed, the strata remaining horizontal or inclined at low
angles. The method of quarrying such deposits is usually simple. Beds
are worked from open-pit quarries, except in a few localities where the
overburden is so heavy that underground methods are used. The depth
of quarrying depends greatly on the thickness of the strata of good stone.
If beds are flat-lying and relatively thin, the pit must be enlarged laterally,
and the extent of the area available and depth of overburden are matters
of first importance. Thus, at Marblehead, Ohio, a 22-foot horizontal
bed of rock with very light overburden has been removed from an area
of more than 1 square mile. If beds are thick, deeper and narrower
quarries may be developed, and this method will involve less extensive
stripping.

In other regions, notably in the Appalachian Mountain district of
eastern United States, the beds are folded so greatly that they may
stand at steep angles, sometimes approaching the vertical. Quarrying
such deposits is more complex. If beds are tilted at steep angles and
are many feet thick, deep quarrying may be pursued. If tilted beds are

CRUSHED AND BROKEN LIMESTONE 453

thin, any lateral extension must be in the direction of the strike or
outcrop. If the beds dip at steep angles, the quarry may be worked to
considerable depth, but removal of waste rock to avoid a dangerous
overhang involves ever-increasing expense as the quarry is deepened.
A narrow working face is a great disadvantage in quarrying steeply
inclined beds of limited thickness; operations are cramped, and a large
daily tonnage is difficult to obtain. This condition may be partly
overcome by quarrying at several levels, so that each bench provides an
additional working face. If work beyond moderate depths is necessary,
resort to underground methods may be advisable.

Quarry Processes. Drilling. — Piston drills are used in many locali-
ties for drilling horizontal, inclined, or vertical holes for primary blasting.
Where an irregular or seamy rock surface makes vertical drilling difficult,
blasting sometimes is done in horizontal or inclined holes known as
"snake holes" driven at the base of the bench. For this purpose piston
drills usually are employed. Some years ago steam supplied the power
to nearly all piston drills. Steam is not economical, as losses of heat by
radiation and condensation are very high, although they may be overcome
somewhat by insulating the pipes or using superheaters. Compressed
air has proved much more economical and is now generally used.

Hand-manipulated compressed-air hammer drills are used to some
extent in primary drilling, but chiefly in secondary drilling in preparing
for pop shots to break up the larger fragments. Although hammer
drills work rapidly, are mobile, and may be held with the hands without
a tripod or bar support, even for holes 12 to 20 feet deep, they are seldom
used for heavy blasting because the drill bit is small. Ordinary hammer
drills use a IJ^-inch bit to start a hole, while many piston drills are
21-i inches in diameter. As the depth occupied by 4 pounds of dynamite
in a hammer-drill hole would accommodate 9 pounds in a piston-drill
hole, the latter is generally preferred. Some quarrymen, however,
believe that the speed of operation of a hammer drill more than com-
pensates for the restricted size of the holes.

Churn drills, or well drills as they are commonly called, have been
used very widely during recent years in preparing for primary blasting.
They may be driven by steam, gasoline, compressed air, or electricity.
The last is most convenient and requires least labor. Churn drills
usually are regarded as the best equipment for benches 20 feet or more
high. The purpose of drilling is to obtain space for the explosive, conse-
quently the only fair method of comparing costs is to consider drilling,
not in terms of cost per foot but rather on the basis of the volume of
space obtained. Churn-drill holes are usually about 6 inches in diameter
and are as large, or nearly as large, at the bottom as at the top, whereas
piston-drill or hammer-drill holes diminish in diameter with increasing
depth. Small holes often are sprung with dynamite to give space for the

454 THE STONE INDUSTRIES

explosive, a tedious and somewhat dangerous operation, but churn-drill
holes seldom require springing.

It is claimed that some improved hammer drills will sink holes to a
depth of 30 to 36 feet and will maintain a diameter of 2 inches at the
bottom. The volume of drill holes varies as the square of the diameter,
therefore a 6-inch churn-drill hole of given depth has nine times the
volume of a 2-inch hole of the same depth. Hence, if no springing is
employed, nine 2-inch holes are needed to provide space for explosives
equal to that supplied by one 6-inch hole. Tripod or hammer-drill
holes of shallower depth may maintain a diameter of 2)^ inches to the
bottom, and about six such holes are equivalent to one churn-drill hole.
It is then evident that the small drill competes most keenly with the
churn drill in shallower holes, where there is little loss in diameter from
top to bottom. Therefore, where springing is not employed the problem
of relative cost resolves itself into the question : Is the total cost per foot,
including repairs, overhead, interest on investment, and similar charges,
six times as great for churn-drill operation as for small drills that bottom
with 2}2-iiich diameter, or nine times as great as for small drills that
bottom with 2-inch diameter? The advantage probably lies with small
drills for low benches and with churn drills for high benches.

Churn drills are most advantageous where the quarry face is 30 to
100 feet high, although they have been used successfully on benches of
not more than 20 feet. As low benches require closer spacing of drill
holes and lighter charges smaller drills usually are preferred. In many
limestone regions the rock is greatly dissected by erosion, leaving a rugged
surface over which it is difficult to move a churn drill, and on which a
timber staging is required. Where such difficulties are encountered
drilling from the face with piston or hammer drills may be preferable.

Steeply inclined beds separated by open or clay-filled seams present
drilling difficulties, for when a churn-drill bit meets a slanting surface
it may be diverted, forming a crooked hole in which tools may bind,
causing great loss of time, with possible loss of the drill bit and abandon-
ment of the hole. To overcome this difficulty, pieces of rock, wood, or
cast iron may be thrown into the hole, so that the drill will pound on
them for some time. When the downward progress of the drill is thus
retarded it enlarges the hole, particularly by cutting away rock that
tends to divert it from its vertical course; thus the hole is straightened.
Other methods of overcoming the difficulty are to explode a stick of
dynamite in the hole or to pour in concrete, which is allowed to set before
drilling is resumed.

In some deposits successive beds may so vary in composition that they
must be applied to different uses. Thus, an upper bed may be suitable
only for road stone and a lower one for furnace flux or for lime burning.
Obviously, such a quarry should not be worked as a single bench and is

CRUSHED AND BROKEN LIMESTONE 455

not adapted for churn drills unless one or more of the separate benches
is at least 20 feet high.

Blasting. — The preliminary shattering of rock in its native bed
is known as "primary blasting," It may be done in piston-drill or
hammer-drill holes, in chambers, or in deep churn-drill holes. The
last method is employed quite generally in quarries where the limestone
is used as crushed stone or for the manufacture of cement, but less com-
monly where it is quarried for lime plants. Where churn-drill blasting
is practiced it usually is conducted on a large scale, and a single blast at
times supplies stone for several months' handling.

Some quarrymen claim that heavy blasts in churn-drill holes break
rock effectively and therefore little secondary blasting is necessary,
while advocates of small-hole blasting maintain that more general dis-
tribution of the explosive in small holes throughout the rock mass breaks
it more completely and less block-hole shooting is necessary than by the
churn-drill-hole method. Undoubtedly, different results are obtained in
different types of rock. In any case, the amount of secondary blasting
depends largely on the quantity of explosive used and the arrangement
of drill holes for the primary blast.

Ammonia dynamite is the explosive most commonly used in quarry
work, although gelatin dynamite is used in wet holes. Choice of explo-
sives depends somewhat on the use to which the stone is to be put.
High-grade explosives may be used where extreme fragmentation is
desired — for example, in rock for cement manufacture. In preparing
stone for lime burning, for furnace flux, or in any crushed form where
fines are undesirable, explosives with a high rate of detonation generally
are not used; dynamite of 30 to 40 per cent strength is most satisfactory.

Liquid oxygen (commonly called "L.O.X.") is used in quarry blasting
to some extent as a substitute for dynamite. It is safer to handle than
ordinary explosives and because it evaporates rapidly there is no danger
from misfires. Cartridges of absorbent paper filled with lampblack
alone or mixed with ground cork are submerged in liquid oxygen until
saturated, then placed in drill holes with as little delay as possible,
tamped with sand, and fired with an electric detonator. The L.O.X.
method of blasting is not feasible, except where quarries are near a
liquid-oxygen-manufacturing plant or where companies are large enough
to justify manufacture of their own supplies of liquid oxygen.

Piston-drill and hammer-drill holes usually are closely spaced because
they can accommodate only small charges. In some quarries where small
drills are used the stone is removed from low benches drilled from the top ;
in others the holes are drilled from the face horizontally or inclined.
In " snake-hole" blasting, where holes are at the base of the bench, ''spring-
ing" is commonly employed to obtain a chamber large enough to hold
an effective charge. In springing, 1 to 4 sticks of dynamite may be used

456 THE STONE INDUSTRIES

in each hole for a first charge, 5 to 8 for a second, 10 to 20 for a third,
and 20 to 30 for a fourth. The holes may be sprung more than four
times, but it is not advisable to make the springing charges very heavy,
for cracks may be opened, which will decrease the effectiveness of the
final charge. For the final charge the chambers and part of the drill
holes are completely filled with explosive, the remainder of the holes
being tamped with clay or rock dust. The charges are fired simultane-
ously by electricity.

Another blasting method, known in the East as "tunnel," in the
Middle West as ''gopher-hole," and on the Pacific coast as "coyote-hole"
blasting consists of firing large charges in tunnels driven into the quarry
face at the floor level. The method is simply snake-hole blasting on a
large scale. The tunnel or drift usually is 3 to 4 feet wide and 4 feet
high. An entry is driven 40 or 50 feet, then right and left cross headings
are driven at right angles to the main leg, thus making a T-shaped
opening. All the dynamite is placed in the cross headings and none in
the main leg. The intersection of the legs and at least half of the main
leg may be filled with lean concrete, or the passages may be blocked by
rough arches of small boulders. The charges are wired in parallel and
fired, preferably by a power current. Trinitrotoluene detonating fuse,
which is described later, may be used to connect the explosive-filled
chambers. This method is best-adapted for quarrying a high face where
the strata are irregular or conditions make it difficult to operate cable
drills.

An important feature of churn-drill work in deep quarries is the sub-
stitution of a single bench for a series of low benches. Disadvantages
of multiple-bench quarrying that may be obviated by using a churn drill
are: (1) Danger to workmen from rock fragments falling from one bench
to another; (2) loss in productive capacity w^here men watch for falls of
rock from the bench above; (3) loss of time and danger of accident where
workmen climb ladders and move explosives and equipment from bench
to bench ; and (4) unduly complicated systems of transporting stone from
different levels.

A single row of churn-drill holes usually is preferred where the quarry
face is 50 or more feet high. Where it is 20 to 30 feet high two to five
rows of holes may be shot at once. The burden (distance of hole from
face) and spacing (distance from hole to hole in the row) may vary con-
siderably in different types of stone. An operator may begin with close
spacing and increase it gradually until the maximum spacing that will
effectively shatter the rock is attained. In average limestone worked
from a quarry having a 35- to 40-foot face the spacing is about 10 to 12
feet and the burden 12 to 15 feet. Spacing and burden increase with
increasing depth of holes but rarely exceed 20 to 25 feet for the deepest
holes.

CRUSHED AND BROKEN LIMESTONE 457

Some blasting experts recommend that where more than one row
of holes is shot at once the back rows should contain at least 10 per cent
more of explosive than the front row. A shorter burden for the back
rows also is recommended, and holes in adjacent rows are
staggered.

In approximately flat-lying beds an open-bed plane sometimes may
be utilized to form the quarry floor; it is then comparatively easy to blast
the rock to the base of the ledge. Where there is no open-bed seam or
where the rock is steeply inclined and there is no joint that may be utilized
as a floor seam, clearing the rock at the toe is more difficult. A common
mistake in drilling is to sink the hole not far enough below the quarry-
floor level. One blasting expert advises a depth of 5 feet below grade in
solid limestone.

The effects of a charge may be reduced greatly or lost entirely if the
drill hole penetrates a mud seam or clay pocket. If open seams occur in
any definite system or exhibit any degree of regularity, it may be possible
to calculate their position at depth and thus avoid them in drilling.
Where large, open, or clay-filled spaces are encountered in drilling it
generally is advisable to abandon the hole. Where the seam is of
moderate size, however, the drill hole may be utilized if the explosive is
kept away from the seam. This may be done by filling the hole with
stemming from a point 3 or 4 feet below the seam to one 3 or 4 feet above
it. Sometimes it is considered better to concrete the cavity and redrill it
when the cement has set.

At many quarries determination of the amount of explosive to use
for the entire charge or for each drill hole is mere guesswork. Neither
high blasting efficiency nor consistent improvement in blasting methods
is to be expected unless the charge is regulated according to the estimated
tonnage of rock to be moved. The tonnage is determined by multiplying
the burden by the spacing by the depth to ascertain the number of cubic
feet of rock ; this is multiplied by the weight of 1 cubic foot of limestone
(usually about 160 pounds) and divided by 2,000. Thus, if the burden is
15 feet, the spacing 12, and the depth 50, the number of short tons of rock

Au ,x. 1 • • V. ^ -11 K 1 • 15 X 12 X 50 X 160
to be moved by the explosive m each drill hole is 2l)00 ~

720 tons. In average quarries 1 pound of 40 per cent ammonia dyna-
mite shatters 3 to 6 tons of rock, depending on its toughness. A first
charge may be estimated on an average basis, say a pound for every
4 tons. For the drill hole above mentioned 180 pounds of dynamite
would constitute a reasonable charge. Results will indicate how cor-
rectly a charge has been estimated. If the rock is not broken enough,
the next charge may be calculated on the basis of 1 pound for every 3)^
tons ; if too greatly shattered the charge may be decreased to a ratio of 1
pound for every 5 tons.

458

THE STONE INDUSTRIES

II
u

fvl

ii
u

Best results are obtained not only by varying the charge but by
changing the spacing or burden of drill holes. Where the rock is brittle
and is pulverized close to the explosive charge, though not broken enough
at a distance, it may be advisable to use smaller drills and thus distribute
the charge more generally throughout the rock mass. In the best-
regulated quarries superintendents keep accurate blasting records, which
show for each large shot the number and depth of holes, spacing, burden,
kind and weight of explosive in each hole, tonnage of rock moved, and

condition of fragmentation. Such records are
of inestimable value in calculating other
blasts.

The charge is modified somewhat to suit
the loading method. For hand loading it is
adjusted to throw the rock out in a thin sheet.
For steam-shovel loading, however, the rock
fragments should lie in a steep ridge near the
quarry face. In quarries with low faces where
several rows of holes are shot at one time to pro-
vide stone for steam-shovel loading, a method
known as "buffer" or "blanket" shooting
sometimes is employed. Part of the broken
stone from the previous blast is left against
the face to offer resistance or confinement to
the charge, thus assuring better fragmentation
and preventing fragments from hurtling over the quarry floor and
damaging or burying tracks. The buffer method is not used where
faces are more than 50 feet high.

In practically all primary shots in quarries the explosives in various
holes are fired simultaneously. If electric detonators are used there are
two general methods of connecting wires when several shots are to be
fired at once. These methods are known as "series connection" and
"parallel" or "multiple connection." The distinguishing characteristics
of each are shown in figure 70. As a rule, shots should be connected in
series when they are to be discharged by hand or by spring-operated
magneto generators, because these generators do not have enough current
capacity to fire in multiple. Where the shots are discharged by current
taken from a power circuit, either series or multiple connection may be
used. If shots are connected in series, a minimum potential of about 13-^
volts per shot will be required if the source of potential is constant; if it
is variable, as is the case when hand- or spring-operated magneto gener-
ators are used, a somewhat larger voltage is desirable. The source of
power used to fire shots connected in series should be capable of supplying
at least 1}^ amperes. When shots are connected in parallel the source of
power should supply about an ampere for every shot to be fired and should

Fig. 70. — Method of con-
necting wires for firing dyna-
mite. A, wiring in series; B,
wiring in parallel.

CRUSHED AND BROKEN LIMESTONE 459

be capable of supplying enough potential to force the total current through
the connecting conductors. A third method, sometimes employed where
many holes are fired at once, is a combination of the above methods and
may be termed a "multiple-series" or "parallel-series" connection.
Holes are connected in series in small groups, and the groups are con-
nected in parallel. Each subseries must have the same resistance.

As a safety precaution to avoid misfires each electric detonator, as
well as the entire circuit, usually is tested with a galvanometer. Strong
detonators are used, and as a rule two are placed in each charge. For
heavy blasting in deep churn-drill holes detonators are distributed at
intervals throughout the length of the charge.

A method of firing gradually being adopted more widely involves
the use of the detonating fuse known in the trade as "Cordeau."
It consists of a lead tube carefully drawn to uniform size and filled
with trinitrotoluene. The fuse extends to the bottom of each
blast hole. After the holes are loaded and tamped a main line of
fuse is placed on the surface and attached to the branches from each hole.
No detonators are placed in the holes; one detonator is attached to the
main line, and when fired the explosive wave flashes along the main line
and into each drill hole. As the rate of detonation of the fuse is very
high all charges are fired at virtually the same time. Greater safety
and increased efficiency are advantages of the detonating fuse. Trinitro-
toluene can not be exploded by friction, fire, or ordinary shock but
requires the shock of a detonator; it is therefore safe to handle and store.
When a fuse is used detonators are not required in the holes, and the
danger from accident during loading is greatly reduced.

The primary shot ordinarily is insufficient to break rock to small
enough sizes for loading, and secondary blasting must be employed.
This process is known locally as "blistering" or "bulldozing." Two
methods are in common use. The "mud-capping," or "adobe" method
consists of placing a stick of dynamite with, a fuse attached on the
surface of the rock to be broken and covering it with a mass of clay, which
tends to confine and direct the explosion toward the rock. This method
usually is inefficient and expensive. By the second method, known as
"blockholing," or "pop-shooting," holes several inches deep are drilled
in the blocks with hammer drills, and a stick, or part of a stick, of dyna-
mite is placed in each hole. Rock dust or clay may be used for stemming.
A number of shots are thus prepared, the fuses lighted, and the blasts
discharged in rapid succession. This method is regarded as at least ten
times more effective than mud-capping for a given quantity of explosive.

Loading. — ^Loading broken stone into cars for removal from the pit is
usually the largest single item of quarry expense. Two general methods
are followed — hand loading and power-shovel loading. Hand loading is
commonly employed .at quarries supplying lime plants or providing flux

460 THE STONE INDUSTRIES

for furnaces. For such uses, chemical purity is demanded, and hand
methods afford a means of selective loading with rejection of siliceous or
otherwise impure fragments. Furthermore, lump stone, with a minimum
of fines, is desired for both these uses, and the hand loader can sledge the
larger masses with a minimum production of fines. The small outlay-
required for loading equipment and the uninterrupted flow of stone to
kilns, furnaces, or crushers are other advantages.

In quarries producing aggregate, road stone, or ballast where chemical
composition is unimportant and where large tonnages are involved a
power shovel is generally used. Some years ago nearly all power shovels
were steam-driven, but both compressed air and electric shovels are now
in use, the latter type having greatly increased in numbers during recent

-^^.'■<ec'^''

Fig. 71. — A large railroad-type shovel loading limestone into cars hauleil by steam

locomotive.

years. The size of shovel is governed by the volume of material to be
handled. For a daily output of 150 to 300 tons of stone small tractor
shovels with 3^- to 1} 4-yard dippers are suitable. Caterpillar tractors
offer special facilities for rapid moving or for working on a soft bottom.
For larger quarries heavier shovels are used. For some large open-pit
operations shovels with dippers capable of handling 5 to 10 tons are
employed. A mechanical shovel can handle rock fragments weighing
several hundred pounds or even more than 1 ton. If a primary blast
breaks the rock moderately well, very little secondary blasting may be
required, whereas in hand loading much secondary blasting and a great
deal of laborious hand sledging are necessary.

The tonnage per man is increased greatly by using power shovels.
Records of a number of quarries a few years ago show an average daily
output of 112 tons per man (pitmen and shovel men only) by power
shovel, contrasted with a daily average of 16 tons per hand loader.

CRUSHED AND BROKEN LIMESTONE 461

The power shovel has some disadvantages. It lacks the ability to
sort materials and, as it handles large fragments, requires accessory
crushing and screening equipment. The large investment involved makes
it more profitable to employ hand-loading methods at many small
quarries, but for large enterprises power-shovel equipment is indispensa-
ble. A typical loading operation is shown in figure 71.

Haulage. — Haulage involves the motive power and equipment
required to convey stone from the loading place at the quarry face to some
point outside the quarry, w^here it is transshipped, crushed, or otherwise
treated. Ordinary transportation equipment may be divided into three
classes — trackage, cars, and haulage systems. The arrangement of tracks
for quarry cars depends on the loading method and the size and shape of
the quarry opening. For hand loading it is desirable for maintenance of a
maximum output to have many working places, each with independent
trackage from the main line. A convenient system for a quarry with a

Fig. 72. — Track arrangement for hand loading at a long quarry face.

long face consists of a main line paralleling the face and a series of spurs
each ending in a Y running from the main line to the face, as shown in
figure 72. Thus, space is provided on one branch for an empty car that
may be loaded while the car already filled is conveyed from the other
branch of the Y to the main track. At some plants, tracks converge
like the spokes of a wheel from the quarry face to the point where the
stone leaves the quarry. Thus cars may be placed at many points
along the face, and those loaded at each working place may be moved
independently. Such a track arrangement is shown in figure 73.

For power-shovel loading two different systems are followed, according
to the width of the working face. Where it is wide enough to permit
necessary movement of cars, the car track parallels the face ; thus cars may
be moved along and filled in succession until a train is loaded. This
system, which is followed in virtually all large quarries, is illustrated in
figure 71.

For mechanical shovel loading at quarries having a narrow face the
track usually runs directly toward the face and ends in a Y, each branch
of which accommodates two or more cars. While the shovel loads stone
into cars on one branch, loaded cars may be shifted from the other branch

462

THE STONE INDUSTRIES

and replaced by empties. This arrangement permits almost continuous
operation. Careful grading of the quarry floor that will permit gravity
movement of loaded cars from the face is an advantage.

At some point in the quarry the method of haulage usually changes.
In pit quarries it is at the foot of the incline up which cars are hauled to
the quarry bank. At shelf quarries it is the place where cars are assembled
for removal in trains. Cars may be removed from shelf quarries over
tracks that are level or have only moderate grades. Transportation
from pit quarries may involve the use of inclined tracks, many of which
are so steep cable haulage is required. On short inclines each car usually
is handled independently, but on long inclines a car may be attached to

Fig. 73. — A limestone quarry worked in two benches; the stone is loaded by hand.

each end of a long cable, the empty being returned while the loaded
car is elevated. The weight of the empty car thus assists in elevating
the loaded one, and both time and power are conserved. Such a system
may have double tracks the entire length of the incline or a single track
below the center switch and a two- or three-rail track above it. Eleva-
tion also may be attained by back-switching on a zigzag track. The
gage of quarry tracks is generally 24 to 42 inches, although standard
railroad gage, 563^^ inches, is occasionally used.

The weight of steel required for tracks depends on the method of
haulage and size of cars. For 2- to 3-ton cars hauled by animals or
moved by gravity, steel weighing 16 pounds to the yard may serve, but a
20- or 25-pound rail is better. For cars or locomotives weighing 7 to
10 tons a minimum weight of 35 to 40 pounds a yard is recommended.

CRUSHED AND BROKEN LIMESTONE

463

Centrifugal force tends to overturn or derail cars on curves if the
outer rail is not elevated adequately. The following table gives the
correct elevation for the outer rail.

Proper Elevation of Outer Rail on Curves of Different Radii for a Speed
OF 6 Miles an Hour on a 30-inch Track

Radius of curve,

Elevation,

Radius of curve,

Elevation,

feet

inches

feet

inches

100

V4.

150

200

The elevation should vary directly with the width of gage and as the
square of the velocity.

Quarry cars are of many different types and sizes. For hand loading,
low cars of 2 to 2^^ tons capacity are most popular, and open-side cars
offer some advantages. For power-shovel loading larger and stronger cars
are required. Side-dump cars are the most common, though end-dump
cars sometimes are used. Although hand-loaded cars should be low, cars
for steam-shovel work should be high, as a high position gives a better
angle of discharge from the shovel dipper.

Quarry cars of many varieties are now in use. Opinions differ
widely among operators as to the advisability of standardizing cars and
reducing the number of sizes and styles employed. Many approve such
standardization, particularly where loading is by contract, as cars of
uniform size and height obviate a possible cause of complaint by loaders
and simplify the fixing of contract prices. On the other hand, many
operators see little prospect of standardization because of the great
differences in quarry conditions, sizes of crushers, and types of haulage.

Various types of motive power are employed. Gravity is the most
economical source and is employed in many quarries where conditions
favor use. Careful adjustment of grades makes car movement in some
quarries largely automatic. A favorite method is to maintain a gentle
down grade from the face to the incline, permitting loaded cars to proceed
by gravity. The empties may be hauled back by horses or mules. Many
operators prefer animal power for short hauls within a quarry or mine,
especially where stone is hand-loaded, but there is a growing tendency to
replace it with smaller types of electric or gasoline locomotives. For
larger operations, particularly where loading is mechanical and the
distance exceeds 500 feet, locomotive haulage generally is employed.
Steam locomotives or ''dinkeys" are widely used and favorably regarded
by many. They may haul trains of 5 to 20 cars. Other operators prefer
gasoline or electric locomotives. Some are small and able to handle 1 to

464 THE STONE INDUSTRIES

3 cars only, although some of the newer gasoline locomotives will
haul 10 to 15 cars. Some large quarries use the Woodford central-
control electric third-rail system. The track is divided into sections,
with an independent current for each; thus cars on different sections are
subject to independent control. Movements of cars are controlled from a
central tower.

Cable-and-drum haulage is commonly employed on inclines. The
so-called "ground hog" or ''barney car" is used on some inclines to take
the place of cable attachment to each individual car. A heavy buffer
mounted on four wheels and attached to the cable operates on a narrow-
gage track between the rails of the car track. On the level or nearly level
floor some distance from the foot of the incline the narrow-gage track
runs into a depression below the car-track level. When the cable is out
the buffer rests in this depression. Loaded cars pass along the track
over the excavation, and as the cable winds on the drum, the buffer comes
up behind the car and pushes it up the incline. Usually only one car is
taken up at a time.

Some quarries maintain smooth roadways with moderate grades and
use truck haulage, eliminating the need of tracks. The crushing plant
may be situated on the quarry floor, and a belt conveyor or bucket
elevator used to carry the crushed stone to the surface. Among the
more unusual means of elevating stone from pit quarries are derricks,
overhead cablew^ays, and traveling cranes.

Crushing. — At quarries where hand-loaded stone is used for lime
burning or furnace flux crushers may not be needed. However, crushing
equipment is an important adjunct of nearly all quarries producing stone
for concrete aggregate, road building, or railroad ballast. At small
quarries stone may be loaded by hand and reduced with portable crushers.
It is generally conceded that it is cheaper to break stone by crushing than
by the use of explosives.

The main types of crushers in general use are the gyratory crusher,
the jaw crusher, double rolls, single rolls, cone, and disk. Details of
construction and operation may be obtained from handbooks on milling
or from manufacturers' catalogs. Gyratory or jaw crushers are used in
nearly all hard-rock quarries. Rolls provided with blunt teeth give
satisfactory service w^here the stone is not exceptionally hard. They
may be operated in pairs (the stone being crushed between them), or
used singly, a baffle plate being substituted for the second roll. Their
wide, hopperlike mouths adapt them for large fragments. Rolls are in
common use at quarries which supply limestone to cement plants.

Crusher size is governed to some extent by the size of stone fragments
that can be loaded and transported. Where stone is loaded with power
shovels, crushers at the best-regulated quarries are large enough to
accommodate any stone fragment the shovel dipper can handle. Some

CRUSHED AND BROKEN LIMESTONE 465

crushers are adapted in size to handle any block that will pass through the
dipper, and shovel runners are instructed to load no fragments of larger
size. An undersize crusher is a serious handicap, as it retards all opera-
tions, demands excessive secondary blasting, and involves heavy repair
charges. Some quarrymen prefer oversize crushers, for while first cost
and power charges may be high, maintenance expense is usually low, and
there are few or no delays with jammed blocks.

Where stone is prepared for lime manufacture or for aggregate, road
stone, or ballast a minimum percentage of fines is desired. Opinions
differ as to the type of crusher that will give the least fines. It is a
generally recognized principle that "choke feeding" — keeping the crusher
filled to capacity — tends to give more fines than when stone is fed
gradually, and not faster than the crusher can handle it. To avoid choke
feeding an apron feed that supplies stone to the crusher in a steady
uniform stream may be employed. At quarries of cement plants condi-
tions are quite the reverse, for as the stone is pulverized before use a
maximum percentage of crusher fines is desired.

Screenmg. — Crushed-stone fragments are assorted by size wdth some
form of screen. For separation of the larger sizes of limestone used for
lime burning or furnace flux an inclined railroad rail or bar grizzly with
33^- to 5-inch spacing sometimes is used. The rotary screen or trommel
is the most widely employed of all types at stone-crushing plants. Screen-
ing equipment has undergone many recent changes. The most note-
worthy change in coarse sizing or scalping is the introduction of rotary
disks, such as the cataract grizzly and the multiroU sizer, as substitutes
for trommels. They consist of a series of rotating disks wdth spacer
between them through which the finer stone drops. As the oversize
stone descends, it successively encounters disks that rotate at greater
speeds, preventing binding and grinding. The advantages claimed are
long wear, absence of vibration, and minimum grinding and breaking of
the stone, as there is no cascading action on the screen. Another change
worthy of mention is increasing use of vibrating screens for finer
sizes.

Washing. — The demand for clean stone with a minimum of fines has
led to the addition of washing equipment at many plants. Washing is
particularly desirable at quarries where clay seams are present, for there
is no other way of easily separating adhesive clay from stone. Washing
is accomplished by directing a jet of water on the stone as it cascades in a
trommel, or as it passes over rotary disks or vibrating screens.

Elevating and Conveying. — Pan conveyors or bucket elevators may be
used to raise stone from crushers to screens or to storage. Belt conveyors
are serviceable if the angle of elevation is low, and stone is conveyed to
storage and from storage to shipping equipment with them at many
plants. Cascading of stone from high elevations is to be avoided,

466 THE STONE INDUSTRIES

particularly if the stone is soft, as undesirable quantities of fines are thus
produced.

Storage of Stone. — Both rate of production and market demands may
fluctuate. In northern climates winter weather may interrupt and
curtail production, and in numerous locations protractd rains may
cause suspension of work in open quarries. Unfavorable quarry condi-
tions, broken equipment, or other unforeseen difficulties may contribute
to these interruptions. On the other hand, demands for the product may
be small at times, particularly in winter, or rush orders may call for
deliveries of stone at a rate much in excess of quarry capacity. Many
operators find it desirable, therefore, to maintain stone in storage to
supply unusual needs or provide for the demands of regular customers
when for one reason or another the crusher plant is idle. Storage
capacity also permits operation of quarries when sales have diminished.
At most plants, storage facilities of some kind are necessary because
delivery of stone directly from crusher to truck, railroad car, or vessel is
not feasible. Separate storage must be maintained for each of the
regular screen sizes. Some convenient storage systems consist of bins or
piles to which stone is carried by belt conveyors and from which it is
loaded directly to trucks or cars through chutes, or to vessels by belt
conveyors. The latter are carried in tunnels beneath the storage piles.
Speedy mechanical handling with a minimum of labor is the first requisite
of an efficient storage system.

Fine Grinding. — As noted in the section on uses, much limestone is
employed in ground form. Because most of the products are too low-
priced to justify the cost of drying a slurry or pulp, dry-grinding processes
generally are used. A variety of grinding mills is in use. Some mills
are of the rollhead type, working like pestle and mortar. Roller mills
of various types, as well as impact, beater, or swinging-hammer mills, are
employed. Ball or pebble mills are preferred by many for very fine-
grained products. Extremely fine subdivision is attained by means of
revolving-plate machines, such as the colloid mill. In pulverizing lime-
stone for paints or ceramic wares in which the iron content must be very
low, flint pebbles rather than steel balls are used. For successful dry
grinding the moisture content of the stone must be low, hence usually it is
passed through a rotary drier. Dry products generally are classified
according to size by air separation, although vibrating screens give good
service, particularly for sizes coarser than 50-mesh.

Removal of finished material from the system as soon as it is produced
is a notable recent advance in fine grinding. A good example of this
process is to be found in the air-swept tube mill, where the finer sizes are
carried away as soon as formed. Grinding efficiency is increased thereby
because the cushioning effect of fine particles is greatly reduced. Closed-
circuit grinding is in general use, the coarser particles being returned to

CRUSHED AND BROKEN LIMESTONE 467

the system for further reduction. It has recently been found advantage-
ous to carry high-circulating loads in ball mills. Very finely divided
material, known as whiting substitute or marble flour, is prepared by wet
or dry processes described previously. (See page 383.)

Operating Costs. — Quarry conditions are so variable that both the
individual items and the total cost are quite diverse in different quarries.
Therefore, it is difficult to estimate costs definitely for a particular
operation, but average costs may have some value. Thoenen^^ obtained
a cost of 67 cents a ton as an average for 30 open-pit limestone quarries
in various parts of the country. For an average quarry operating on a
large scale this total might be distributed as follows: Stripping, 6 cents;
drilling, 9.5 cents; explosives, 7.5 cents; loading (hand), 22 cents; mucking,
6 cents; haulage, 5 cents; repairs, taxes, and similar charges, 5.5 cents;
interest and amortization, 5.5 cents; total, 67 cents. If a power shovel
is used the direct-loading cost in general would be much less than 22
cents, but with interest on investment, together with additional crushing
expense, the total would probably differ little from the hand-loading cost.
It must be emphasized that some of these items will be much higher and
some much lower under the peculiar conditions of individual quarries.
A cost analysis by Thoenen'^° of 110 limestone quarries grouped according
to size and equipment show direct quarrying and crushing costs ranging
from 35 to 95 cents a ton.

Underground Mining Methods. — Limestone is obtained chiefly from
open-pit quarries. Where the overburden is thin, quarrying by deep-hole
blasting and power-shovel loading is the cheapest method of obtaining
stone. However, conditions do not always favor open-pit work, and
more and more operators are finding it advantageous to employ under-
ground methods. The chief factors tending toward use of the mining
method are (1) a heavy overburden of soil or inferior rock which blankets
a flat-lying deposit of good limestone, (2) inclination of the beds of service-
able stone that demands too great an extension of the pit along the strike
or outcrop and results in an increasing overburden as the pit is enlarged
in the direction of dip, and (3) the necessity for working at increasing
depths as surface deposits are exhausted. Limestone is too low in price
to justify the expense of mine timbering, except possibly in shafts or
entries, hence mining is successful only where the rock is strong and
massive enough to permit maintenance of safe roofs in drifts and cham-
bers, with supporting pillars spaced not less than 25 or 30 feet apart.

The principal advantages of underground work are avoidance of
stripping, freedom from contamination by overburden, and protection

^» Thoenen, J. R., Underground Limestone Mining. Bur. of Mines Bull. 262,
1926, p. 94.

'" Thoenen, J. R., Study of Quarry Costs. Bur. of Mines Rept. of Investigations
2911, 1929, p. 2.

468 THE STONE INDUSTRIES

to laborers from snow, ice, and rain. Some disadvantages are to be
noted. Drilling and blasting are more costly than in open-pit work, the
proportion of fines is increased, and 20 to 25 per cent of the rock is unused,
as it must remain in the form of pillars for roof support.

Thoenen'^'^ found that the average cost of mining limestone in the United
States was about 96.4 cents a ton and therefore exceeded the average cost
of quarrying by about 30 cents a ton. Hence, under average conditions,
if the stripping cost exceeds 30 cents a ton of rock uncovered, it would be
cheaper to mine. This rule, however, must not be taken too literally,
for conditions may not favor underground methods. No set rule govern-
ing a choice between underground and open-pit work can be given;
each operation is an individual problem that must be considered on its
merits. Weight must be given conditions of roof, strength and soundness
of rock, and presence of floor and roof seams, and to other conditions on
which successful underground work depends.

In 1925 at least 64 underground limestone mines were operating in the
United States, and new ones have been developed since that date. Some
are very extensive; one mine in Pennsylvania produces normally about
3,500 tons of stone a day.

Most mines are of the adit or tunnel type; that is, the entrance is an
approximately horizontal tunnel from an outcrop or from the side of an
open pit. A few mines are of the vertical or inclined-shaft type. Several
different methods of development are followed. The simplest is the
single-breast stope, which is best-adapted to thin, flat beds. The tunnel
is worked out in all directions on a constantly enlarged circumference,
and pillars for roof support are left at irregular intervals. A more
systematic method is known as room-and-pillar mining. Square or rib
pillars are left in regular rows, with rooms and haulageways between.
Tunnels may be advanced by carrying a breast stope just below the roof,
thus forming a bench in which holes for blasting are drilled vertically to
the floor level. Another method is to carry the breast stope at the floor
level and to drill upward in the so-called back stope. Many modifica-
tions of the methods are followed. Thoenen gives details of underground
mining in the bulletin already mentioned.

Modification of Method According to Use. — The major quarry proc-
esses, from stripping the rock surface through all stages of preparation
to storage of the finished product, have been covered in preceding pages.
Although they apply in general to all industries producing crushed and
broken limestone, quarry methods differ somewhat according to the use
for which the stone is prepared. Outstanding differences in method for
the chief subdivisions of the limestone industry are discussed briefly
in following paragraphs.

^1 Thoenen, J. R., Underground Limestone Mining. Bur. of Mines Bull. 262,
1926, p. 10.

CRUSHED AND BROKEN LIMESTONE 469

Methods at Cement-plant Quarries. — Cement can be manufactured
profitably only on a fairly large scale; hence, quarries that supply cement
mills with limestone are, as a rule, well-equipped for mass production.
Blasting is usually in deep churn-drill holes, and heavy charges are used
because maximum breakage of rock is desired. Clean stripping of
overburden is unnecessary if the cover consists of suitable clay, because
clay must be added to limestone to make a satisfactory mixture. To
maintain a proper proportion of lime, alumina, and silica and to keep
iron and magnesia within required limits, chemical control is required.
If the rock is variable from point to point laterally it is usually desirable
to work a long face to equalize the composition. At some quarries cars
loaded at successive points along the face are unloaded in regular rotation.
If a quarry has high-calcium stone at one end and low-calcium at the
other, power shovels are operated simultaneously at both ends, and cars
from the two loading places dumped alternately. If successive hori-
zontal beds vary in composition from top to bottom of a high working
face, blasting the full height of the face as a single bench also tends to
mix stone from different ledges. Uniform distribution throughout the
length of a large storage bin assists in equalizing composition.

Methods at Lime-plant Quarries. — Most of the lime now manufactured
in the United States is calcined in shaft kilns. Stone under 4 inches in
size is undesirable, because fines retard draft. Therefore, the object in
blasting is not to attain maximum fragmentation, as in cement-plant
quarries, but rather to shatter the rock with a minimum production of fines.
Moderate charges are used, and the explosive may be of lower grade
than that employed at cement-plant quarries, even though more second-
ary blasting is required. Many operators prefer hand-loading methods,
because hand sledging produces less fines than mechanical crushing.
The impurity in the stone should be preferably under 2 or 3 per cent,
and hand loading has the added advantage of permitting selection
according to quality. The necessity for purity in the stone demands
clean stripping of overburden. If clay pockets or seams are present
some siliceous impurity will be mixed with the broken stone. If hand-
loading methods are followed clay and fines are removed to the dump as a
mucking process. If mechanical shovels are used screening is necessary,
and some plants have both screening and washing equipment.

Methods at Fluxing-stone Quarries. — Methods at quarries producing
furnace flux are similar to those at lime plants, because for both uses lump
stone of high purity is demanded. However, many of the fluxing-stone
quarries are so large that mechanical loading is regarded as a necessity.
Where power shovels are used they must be followed by crushers and
screens, and washing equipment is not uncommon. Where hand-loading
methods are employed forks often are used to load the smaller fragments
to eliminate both fines and the sand or clay associated with them.

470 THE STONE INDUSTRIES

Methods at Crushed-stone Quarries. — Production of road stone, con-
crete aggregate, and railroad ballast has one feature in common with the
quarrying of fluxing stone and raw material for lime manufacture, namely,
the undesirability of fines, as the smaller sizes and dust usually are most
difficult to market. Here the similarity ends. For the crushed-stone
industries such physical properties of the stone as hardness, toughness,
and porosity have much greater importance than chemical composition.
This is evident from the fact that rocks as diverse in composition as
granite and limestone are used in identical ways as crushed stone. There-
fore, in quarry processes little or no attention is given to variations in
chemical composition. Except at small local quarries, mechanical
handling is the rule because the product commands so low a price that
quantity output requiring a minimum of labor is necessary if the project
is to be an economic success.

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Publishing Corporation, Chicago.

CRUSHED AND BROKEN LIMESTONE 471

Eckel, E. C, and others. Portland Cement Materials and Industry in the United

States. U. S. Geol. Survey Bull. 522, 1913, 401 pp.
FuLLERTON, W. J., and Cox, A. W. Method and Cost of Quarrying, Crushing, and

Grinding Limestone at Catskill Plant of North American Cement Corporation,

Catskill, N. Y. Bur. of Mines Inf. Circ. 6522, 1931, 15 pp.
Ganser, J. W. Method and Cost of Quarrying Limestone at Quarry of Trinity

Portland Cement Co., Fort Worth, Tex. Bur. of Mines Inf. Circ. 6513, 1931,

13 pp.
GouDGE, M. F. Limestone in Industry. Canadian Min. and Met. Bull. 217, May

1930, pp. 698-712.
HoTCHKiss, W. 0., and Steidtmann, Edward. Limestone Road Materials of Wis-
consin. Wisconsin Geol. and Nat. History Survey Bull. 34, Econ. Ser. 16,

1914, 137 pp.
Kirk, Raymond E. The Manufacture of Portland Cement from Marl. Univ. of

Minnesota Eng. Exp. Sta. Bull. 4, 1926, 98 pp.
Krey, Frank, and Lamar, J. E. Limestone Resources of Illinois. Illinois State

Geol. Survey Bull. 40, 1925, 392 pp.
Lamar, J. E., and Willman, H. B. High-calcium Limestone near Morris, 111.

Illinois State Geol. Survey Rept. of Investigations 23, 1931, 26 pp.
Lewis, J. Volney, and Kummel, H. B. The Geology of New Jersey. Geol. Survey

of New Jersey Bull. 14, 1915, 146 pp.
Logan, W. N. The Structural Materials of Mississippi. Mississippi State Geol.

Survey Bull. 9, 1911, 78 pp.
LouGHLiN, G. F., Berry, E. W., and Cushman, J. A. Limestones and Marls of

North Carolina. North Carolina Geol. and Econ. Sur\^ey Bull. 28, 1921, 211 pp.
Lowe, E. N. Road-making Materials of Mississippi. Mississippi State Geol.

Survey Bull. 16, 1920, 139 pp.
Marsh, Robert, Jr. Steam-Shovel Mining. McGraw-Hill Book Company, Inc.,

New York, 1920, 258 pp.
McAnally, S. G. Mining, Crushing, and Grinding Methods and Costs at the

ReUance Cement Rock Quarry of the Giant Portland Cement Co. Bur. of

Mines Inf. Circ. 6448, 1931, 16 pp.
Miller, B. L. Limestones of Pennsylvania. Topog. and Geol. Survey of Pennsyl-
vania Bull. M 7, 1925, 368 pp.
Morrison, George A. Mining and Crushing Methods and Costs at the West Penn

Cement Co., Limestone Mine, West Winfield, Pa. Bur. of Mines Inf. Circ.

6446, 1931, 21 pp.
MossoM, Stuart. A Preliminary Report on the Limestones and Marls of Florida.

Florida Geol. Survey Sixteenth Ann. Rept., 1925, pp. 33-195.
National Lime Association. Lime — Its Use and Value in the Industrial and Chemical

Processes. Washington, 1930, 88 pp.
Newland, D. H. The Mineral Resources of the State of New York. New York

State Museum Bull. 223, 224, 1919, pp. 255-272.
Orton, Edward, Jr., and Peppel, S. V. Limestone Resources and the Lime Indus-
try in Ohio. Geological Survey of Ohio, 4th ser.. Bull. 4, 1906, 356 pp.
Pit and Quarrj' (a monthly magazine). Complete Service Publishing Co., Chicago.
Pit and Quarry Handbook (with which is consolidated the directory of cement,

gypsum, lime, sand, gravel, and crushed-stone plants). Complete Service

Publishing Co., Chicago, published annually.
Quarry Managers' Journal. Institute of Quarrying, London; publishing office,

Birmingham, England.
Quarry and Roadmaking. The Colliery Guardian Co., Ltd., London.
Rock Products (a monthly magazine). Tradepress Publishing Corporation, Chicago.

472 THE STONE INDUSTRIES

Shedd, Solon. Cement Materials and Industry in the State of Washington. Wash-
ington Geol. Survey Bull. 4, 1912, 268 pp.

Smith, Eugene A., and McCalley, Henry. Index to the Mineral Resources of
Alabama. Geol. Survey of Alabama, 1904, pp. 27-29.

Smith, R. A. Limestones of Michigan. Michigan Geol. and Biolog. Survey Pub.
21, Geol. Ser. 17, part II, 1916, pp. 101-311.

Steidtmann, Edward. Limestones and Marls of Wisconsin. Wisconsin Geol.
and Nat. Hist. Sun/ey Bull. 66, Econ. Ser. 22, 1924, 208 pp.

Thoenen, J. R. Underground Limestone Mining. Bur. of Mines Bull. 262, 1926,
100 pp.

Trainer, David W., Jr. The Tully Limestone of Central New York. New York
State Museum Bull. 291, 1932, 43 pp.

CHAPTER XVIII

CRUSHED AND BROKEN STONE OTHER THAN LIMESTONE

GENERAL FEATURES

Although Hmestone is by far the largest source of crushed and broken
stone, other varieties are used extensively in many places. The chief
types so used are basalt (trap), granite, and sandstone. In statistical
compilations of the United States Bureau of Mines a miscellaneous group
includes all rocks not definitely identified with the major varieties.
Trap is a commercial term comprising fine-grained, basic igneous
rocks, such as diabase and basalt, but is somewhat indefinite in its applica-
tion, as it includes various rocks of uncertain composition. The term
granite, as used commercially, includes, in addition to true granite, syenite,
diorite, gabbro, and other medium- or coarse-grained igneous rocks.
Sandstone includes the highly indurated varieties known as quartzites.
Miscellaneous stone includes light-colored volcanic rocks (rhyolite,
trachyte, or tuff), schists, boulders from river beds, slate, serpentine,
fiint, and many other diverse sorts.

USES

Unlike limestones, most of the stones in these four groups are chemi-
cally inert and therefore have limited use outside the main fields of
application, namely, as concrete aggregate, road material, and railroad
ballast. Any of them may be used for riprap where the need exists.
Special uses may be briefly mentioned.

Various types of igneous rock are used as roofing gravel or as granules
for surfacing prepared roofing. More than 117,500 tons of granules made
of stone other than slate were sold in 1930. Their value at the mill was
about $727,000. Another important special application is the utilization
of quartzite for the manufacture of silica brick or as furnace lining or
furnace sand. Quartzite suitable for such uses is known as ganister.
For its principal use it is ground to a powder, mixed with about 2 per cent
lime as a binder, molded into bricks, and calcined. Silica brick are
classed as refractories and used extensively in lining coke ovens and
metallurgical furnaces. About 1,000,000 tons of ganister were produced
in 1929, but owing to furnace inactivity production fell to about 120,000
tons in 1932. Production is centered chiefly in Pennsylvania and
Wisconsin, with a smaller output in Alabama, Arizona, California,
Colorado, Illinois, Maryland, Minnesota, Montana, Ohio, South Dakota,
Tennessee, Washington, and West Virginia.

473

474 THE STONE INDUSTRIES

Outlets for waste stone, comprising varieties other than limestone,
are limited. Waste trap-rock and granite screenings are employed for
road surfacing and to a limited extent for filler in asphalt and other
products. Granite chips are used to face concrete blocks to make them
resemble stone and to give color to artificial stone and terrazzo. Sand-
stone fines are utilized as building, paving, and furnace and glass sand,
and to some extent as asphalt filler. Coarser sizes are sold as roofing
granules. Sandstone screenings may be used for the manufacture of
sand-lime brick, and screenings of various miscellaneous stones in the
same way as granite or trap. Serpentine chips are sold for terrazzo
flooring material.

GENERAL DISTRIBUTION AND VALUE

Igneous rocks are most abundant in rugged territory traversed by
few roads or railroads and remote from large centers of population.
Hence, the largest areas are those least used. Chief developments are in
outcrops, sometimes isolated and comparatively limited in extent, near
large cities.

Granites and other coarse-grained igneous rocks are utilized exten-
sively in New England and throughout other States traversed by the
Appalachian Mountains, as well as in Wisconsin and California. The
finer-grained, dark igneous rocks (basalt) are used extensively in Con-
necticut, Massachusetts, New Jersey, New York, Pennsylvania, Wash-
ington, and California. The fine-grained, light-colored igneous rocks
(trachyte, andesite, rhyolite, and tuff) are confined principally to the
Rocky Mountain and Western States, where vulcanism was much more
recent than in middle-western and eastern territory. More than half the
miscellaneous stone is reported from California. Other important
producers west of the Mississippi River are, Arizona, Nevada, Colorado,
Texas, and Arkansas. The principal output in the East is from Massa-
chusetts and Pennsylvania.

The chief centers of production of crushed sandstone are in California,
New York, Pennsylvania, South Dakota, and Washington. Sandstone
is used extensively for riprap in Oregon and Missouri.

The tonnage and value of production of the major groups by States
are shown in following tables compiled by the United States Bureau of
Mines. Figures for 1930 are given, as they are probably more typical
than those of later years.

CRUSHED STONE OTHER THAN LIMESTONE

475

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477

Basalt and Related Rocks (Trap Rock) Sold or Used by Producers in the

United States in 1930 by States

(Quantities approximate)

State

Short
tons

Value

State

Short
tons

Value

California

Connecticut

Hawaii

794,420
2,337,720
277,520
408,500
325,100
1,743,890
118,490
155,130
494,560

$ 903,570
2,440,151
442,869
378,038
470,441
1,874,042
202,335
302,115
131,502

New Jersey

New York

Oregon

Pennsylvania ....

Texas

Virginia

Washington

Wisconsin

Undistributed

2,412,970
1,235,580
1,476,050

1,203,370

1,318,720

230,230

$ 3,313,917
1,989,416
1,419,734

Idaho

1,714,137

Maryland

Massachusetts. . . .

Michigan

Minnesota

Montana

*
*

1,200,323

270,441

14,532,250

$17,053,031

* Included under Undistributed.

Of the total given in the preceding table 39,450 tons, valued at
$74,840, are classed as dimension stone, but figures are not available in
sufficient detail to distribute them by States.

INDUSTRIES BY STATES

In following pages the distribution, production centers, and uses of
basalt, granite, sandstone, and miscellaneous stone are covered briefly by
States in alphabetical order. Uses are mentioned only where unusual
applications outside the major fields (concrete aggregate, road stone, and
ballast) are involved. The stones of each State are covered in the
following order: Basalt (trap), granite, sandstone, and miscellaneous
stone. Where no mention is made of one or more of these varieties it
may be inferred that there are no developments of commercial importance.
Similarly, where an individual State is not mentioned, none of the
varieties is utilized therein to an extent to merit comment.

Alabama. — The Wisner (Cambrian) quartzite is quarried near
Anniston, Calhoun County, and to a smaller extent in Cherokee County,
for use as ganister to make silica brick. Canister is produced also near
Birmingham, Jefferson County. The extensive metallurgical industries
centered at Birmingham require silica brick for furnace linings.

Arizona. — ^Large quantities of massive sandstone are quarried near
Querino, Apache County for use as riprap. Quartzite (ganister) is
quarried in Cochise County for furnace lining. Stone of types included
in the miscellaneous group is abundant in Arizona. Decomposed granite
is quarried in Gila County, crushed gravel near Phoenix, Maricopa County,
and rock known as "caliche" in Pinal County. Caliche is defined as a

478 THE STONE INDUSTRIES

form of earthy impure limestone characteristic of the hot arid regions of
the Southwest.

Arkansas. — Sandstones and miscellaneous rocks occur in various
parts of Arkansas, but chief production is confined to central and western
districts. Sandstone has been quarried extensively at Fort Smith,
Sebastian County, near the western border of the State. Stone classed
as sandstone or argillite is quarried on a large scale at Little Rock,
Pulaski County, central Arkansas. Boulders are crushed for road build-
ing in this district.

California.- — Rocks of many varieties suitable for crushing occur in
various parts of California. Chief developments are in the two metro-
politan areas, Los Angeles and San Francisco, but numerous quarries
have been opened in other localities. Basalts are abundant and give
excellent service in building roads and for concrete aggregate. Loose
boulders of granite and other rocks occurring in many localities are
sources of crushed stone. Volcanic tuff, andesite, felsite porphyry,
decayed granite, serpentine, and other rock types of the miscellaneous
class are abundant.

Basalt is quarried extensively in the San Francisco district. Quarries
nearest the city are in San Francisco and San Mateo Counties and at
Richmond, El Cerrito, and Stege, Contra Costa County. Other quarry
centers supplying basalt to this populous territory are at Mayfield,
Santa Clara County; Napa, Napa County; and Thomasson, Solano
County. Large quarries are operated in Sonoma and Lake Counties.
Basalt is quarried also in Del Norte County in the extreme northwest.
Roofing granules consisting of trap rock are produced in large quantities
at Angels Camp, Calaveras County, in east-central California. Santa
Barbara is the only county in southern California that produces any
considerable quantity of crushed stone classed as basalt.

Granites are abundant. Very large quarries are operated at Logan,
San Benito County, to assist in supplying the extensive demands for
crushed stone in the San Francisco area. Crushed granite is produced
also in Humboldt, Madera, Riverside, and Sacramento Counties. Pro-
duction of riprap is reported from San Bernardino County.

Sandstone quarrying is likewise centered chiefly near San Francisco.
Large quarries are operated at San Rafael and Green Brae, Marin
County, and smaller quarries at El Cerrito, Contra Costa County, and
Leona and San Leandro, Alameda County. San Mateo County also
produces sandstone. The only large center of quarrying in southern
California is in Santa Barbara County. Quartzite (ganister) for the
manufacture of silica brick is quarried near San Bernardino, San
Bernardino County. Some of the basalt and sandstone quarries are
temporary and operate for only a year or two to supply stone for special
projects.

CRUSHED STONE OTHER THAN LIMESTONE 479

Bituminous sandstone is obtained in two localities in the State.
Fifty-foot beds of Miocene age occur on the coast about 5 miles northwest
of Santa Cruz, Santa Cruz County, and Pleistocene asphaltic sands near
Carpenteria, in southeastern Santa Barbara County. Materials from
both localities have been utilized in highway construction for many
years.

Rocks classed as miscellaneous occur very widely in California.
Quarries, some of them exceptionally large, are worked in more than 20
counties distributed throughout almost the entire length and breadth of
the State. California produces about 70 per cent of all stone classed as
miscellaneous quarried in the United States.

Beginning with counties nearest the southern boundary the first
commercial rock encountered is a felsite porphyry quarried at Sunnyside,
Spring Valley, Otay, and Chollas, San Diego County. Lava and other
volcanics also are produced in this county. Altered granite is quarried in
Orange County. The most extensive crushed-stone enterprises in the
State are in Los Angeles County. Many thousand tons of andesite and
decomposed granite are quarried at Avalon on Santa Catalina Island.
Stone of various sorts is quarried and crushed at Hollywood, Altadena,
Baldwin Park, Culver City, El Monte, Irwindale, Los Angeles, Whittier,
and other points ; the bulk of it is river-wash boulders and gravel. Activity
in so many centers is doubtless due to the rapid growth in population of
this region.

A red stone is used for the manufacture of roofing granules in San
Bernardino County. Crushed stone is prepared in Santa Barbara
County and at Inyokern and Mojave, Kern County. Substantial
amounts of volcanic tuff are quarried at Lone Pine and Olancha, Inyo
County; and large companies are engaged in crushing boulders at Friant
and serpentine at Piedra, Fresno County. Plants of moderate size pro-
duce crushed stone at Cathay, Mariposa County; Oakdale, Stanislaus
County; and Sacramento and Fairoaks, Sacramento County. The
products of the latter county are chiefly boulders and gravel from gold-
dredger tailings. The production of miscellaneous stone in the San
Francisco district is limited to small quarries in Alameda and Sonoma
Counties.

In north-central California production of crushed stone is reported in
Lake and Glenn Counties, and very large boulder-crushing operations
from gold-dredger tailings are established at Chico and Oroville, Butte
County. There are smaller quarries at Truckee and Nevada City,
Nevada County, and at several points in Sierra County. At Crescent
City, Del Norte County, in the extreme northwest large quantities of
schist are employed in harbor w'ork and as crushed stone. Road-building
requirements in northern California are supplied in part from indefinitely
classified stone quarried at Susanville, Lassan County; Flume and other

480 THE STONE INDUSTRIES

points in Shasta County; Weaverville, Trinity County; and Blue Lake,
Garberville, and Trinidad, Humboldt County.

Colorado. — Granite, sandstone, and miscellaneous rocks are the chief
sources of crushed stone in Colorado. Granites are plentiful and occur
near many towns. Basalt is available but is used in small amount.

The largest granite quarry is near Golden, Jefferson County. Sand-
stone is quarried in Boulder County; at Canon City and other points in
Fremont County; and near Stone City, Pueblo County. Of the miscel-
laneous types phonolite is crushed in Teller County and at Cripple Creek,
El Paso County. Volcanic ash or tuff is obtained in Routt County, and a
large crushed-stone plant is operated at Trinidad, Las Animas County.

Connecticut. — Basalt (trap rock), occurring in north and south ridges
in the central lowland area, is the most prolific source of crushed stone in
Connecticut. It is tough and durable and has a high reputation as
road material. Granites and granite gneisses abound in both the eastern
and western highlands but are not used extensively. Sandstones of the
Connecticut River Valley are supplementary sources of raw material.

Very extensive trap-rock quarries, with large modern crushing plants,
are operated at many places in central and southern Connecticut.
Among the principal centers of activity are Newington, Farmington,
Suffield, New Britain, West Hartford, Plainville, and Rockyhill, Hartford
County; Cheshire, Hamden, Meriden, New Haven, Wallingford, and
North Branford, New Haven County; and Bridgeport, Fairfield County.
Small amounts of granite for riprap and concrete aggregate are produced
in Hartford, Middlesex, Windham, and New London Counties. The
chief center of sandstone production is at Cromwell, Middlesex County.

Delaware. — Rocks in Delaware suitable for crushing are confined
almost entirely to granites and gneisses occurring near the northern end
of the State. Large quarries for production of riprap, road stone, and
concrete aggregate are operated near Wilmington, Newcastle County.

District of Columbia. — Granite gneiss occurring in the northern
section of the District of Columbia is quarried locally at times for con-
crete aggregate and street paving.

Florida. — Very little solid rock other than limestone occurs in Florida.
The only output worthy of mention consists of crushed stone, classed as
flint, produced at Morriston, Marion County.

Georgia. — The abundant granites of Georgia are crushed in moderate
amount, principally as by-products of the paving-block and curbstone
industry, at Lithonia, De Kalb County. Crushed granite is produced
also at Stockbridge, Henry County; at Toccoa, Stevens County; and in
Elbert County. Granite riprap is obtained in Oglethorpe County.

Idaho. — Rocks designated basalt or trap are quarried in northern
Idaho, chiefly by the State or counties for highway work. There are
quarries near Lewiston, Nez Perce County; and in Latah, Clearwater,

CRUSHED STONE OTHER THAN LIMESTONE 481

Bonner, Lewis, Benewah, and Kootenai Counties. Some quarries are
temporary, being worked for a limited time only to supply stone for special
projects. Rock classed in the miscellaneous group is quarried for railway
ballast at Crossport, Boundary County, and altered granite is quarried
in Clearwater County.

Illinois. — Very little rock other than limestone is used for the manu-
facture of crushed stone in Illinois. Most sandstones occurring in the
State are consolidated too loosely for such use; but a more indurated
variety, known as "novaculite," quarried at Tamms, Alexander County,
is used for road base. A small amount of ganister also is produced in
this county.

Kansas. — Quartzite is prepared for use as concrete aggregate near
Lincoln, Lincoln County. An asphaltic sandstone, with a bituminous
content of 6 to 12 percent, was quarried actively in and near Pleasanton,
Linn County, in 1932.

Kentucky. — The bituminous Kentucky sandstones are the most
important bituminous or asphaltic rocks quarried for road building in
the United States. As indicated in the table on page 482 compiled by
the United States Bureau of Mines, $2,000,000 to $3,000,000 worth is
mined annually in Kentucky.

Extensive deposits of the sandstone, which is of Carboniferous age,
occur in Edmonson, Breckenridge, Grayson, and Hardin Counties in
west-central Kentucky. At Kyrock and Asphalt, Edmonson County,
the commercial beds, which are quarried throughout the year, are about
20 feet thick and covered with 40 to 60 feet of sandstone overburden.
The latter is blasted, loaded with steam shovels, and removed as waste.
After blasting the bituminous rock is loaded by hand to permit careful
selection. A large output has been maintained for many years. The
product is shipped by barges to railway lines, either at Bowling Green or
Rockport, and is marketed in at least 35 States. The bituminous content
of the stone as shipped to customers is a little over 7 per cent. Other
production centers are Elizabethtown and Summit, Hardin County; and
Big Clifty and Leitchfield, Grayson County; all have railroad
facilities.

Maine. — Both granite and trap rock are quarried near Portland,
Cumberland County. Quarries producing granite as dimension stone in
Franklin, Hancock, and York Counties supply a small amount of by-
product crushed stone and riprap. Miscellaneous types are crushed at
Lewiston, Androscoggin County, and at various points in Cumberland,
Somerset, and other counties.

Maryland. — Basalt is an important source of crushed stone in Mary-
land. Several large quarries are operated at Woodlawn, Loch Raven,
and other points in Baltimore County. Crushed stone and riprap are
obtained at Port Deposit, Cecil County. Very large quarries, chiefly

4S2

THE STONE INDUSTRIES

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CRUSHED STONE OTHER THAN LIMESTONE 483

for the production of railroad ballast, operate on a bluff overlooking the
Susquehanna River near Havre de Grace, Harford County. Granite is
quarried near Baltimore and at Blue Mount and other points in Balti-
more County. Crushed stone is produced as a by-product of a dimension-
granite enterprise in western Baltimore County near Woodstock and in
southern Montgomery County near the District of Columbia. Ganister
is produced near Corrigansville, Allegany County. Crushed stone of
miscellaneous types, including serpentine, is quarried near Baltimore.

Massachusetts. — Basalt is the rock most widely used for crushing in
Massachusetts, There are more than 20 important centers of produc-
tion, and several quarries are among the largest in the United States.
Extensive market demands in the Boston metropolitan area and in near-
by cities are met from quarries at Lawrence, Beverly, Methuen, Salem,
and Swampscott, Essex County; and at Holliston, Pepperell, Sherborn,
Newton, Stony Brook, and Winchester, Middlesex County. The largest
plants are at the two last locations and at Swampscott. Quarries are
numerous in western Massachusetts. Many thousand tons of crushed
basalt are produced at Westfield, West Springfield, and Holyoke, Hamden
County. Other important quarry centers are at Amherst, Hampshire
County; and Greenfield, Franklin County.

Granite is quarried extensively in several eastern counties. Crushed
stone and riprap are produced at Salem, Rockport, Bay View, and Pigeon
Cove, Essex County. A very large quarry, chiefly for production of
road stone, is operated at West Roxbury, Suffolk County. The well-
known Quincy district of Norfolk County, where large amounts of
monumental and building granites are quarried, also provides many thou-
sands of tons of crushed granite. Other quarries operate in Plymouth
County; and at Acushnet and Westport, Bristol County.

Miscellaneous rocks contribute materially to the large output of
crushed stone in eastern Massachusetts. Rock classed as felsite is
quarried extensively at Saugus, Essex County, while flint stone and other
rocks are crushed at Southbridge, Worcester County. Rocks of volcanic
origin are quarried at Maiden, Middlesex County, and at Roslindale and
Revere, Suffolk County. A conglomerate is crushed at Jamaica Plain
and West Roxbury, Suffolk County.

Michigan. — There are two important centers of basalt production in
the northern peninsula of Michigan. Crushed basalt is used in highway
and street paving in and near Ishpeming and Negaunee, Marquette
County. A quarry at Negaunee provides stone for the manufacture of
granules used in the same way as slate granules for surfacing prepared
roofing. Considerable quantities of crushed basalt are produced at
Wakefield, Gogebic County. Crushed basalt is produced also in Hough-
ton and Iron Counties. Sandstone quarried near Marquette, Marquette
County, is used in highway construction.

484 THE STONE INDUSTRIES

Minnesota. — Basalt is applied to commercial use in St. Louis County,
northeastern Minnesota. Massive occurrences at Duluth and Biwabik
are quarried for highway work and concrete aggregate. Basaltic rock is
quarried at Ely for the manufacture of roofing granules.

Granite is quarried for road stone at Two Harbors in southern Lake
County. A very extensive block-granite industry is centered in Stearns
County, and waste from this district is utilized to some extent for the
manufacture of crushed products.

Sandstone is, or has been, utilized in three localities. Crushed stone
is produced at Sandstone, Pine County, in conjunction with a large
paving-block, curbing, and building-stone industry. The Sioux quartzite,
of Huronian age, is crushed at times for concrete aggregate at Pipestone,
Pipestone County, and at Jasper and Luverne, Rock County, in the
southwestern corner of the State. Quartzite quarried at Pipestone is also
manufactured into roofing granules. A northeastern extension of the
Sioux quartzite has been quarried for crushed-stone manufacture at New
Ulm, Nicollet County.

Missouri. — A small output of crushed granite is reported from
Graniteville, Iron County, and from Wayne County. Sandstone riprap
is obtained from quarries at Miami Station, Carroll County. Of the
miscellaneous varieties flint is crushed for concrete aggregate in Greene
County, rhyolite for road stone at Pilot Knob, Iron County, and "chats"
(siliceous gangue) in the lead-zinc districts.

Montana. — Riprap for use along railway lines is quarried from basaltic
rock in Flathead and Lincoln Counties in northwestern Montana, and
granite for similar use is obtained in Lewis and Clark County. At times
small amounts of altered-granite riprap are quarried in Silver Bow
County. A little sandstone (quartzite) is produced annually in Cascade
County for the manufacture of silica brick.

New Hampshire. — Granite riprap and concrete aggregate are obtained
at Redstone, Carroll County, and both crushed granite and roofing
granules in Coos County. Several large companies producing granite as
dimension stone at Milford, Hillsborough County, and Concord, Merri-
mack County, convert part of their waste rock into riprap and crushed
stone. Granite for use as road stone is quarried also in Stafford County.
A mica schist occurring at Warren, Grafton County, is crushed into
poultry grit, and small fragments are used for manufacture of cement
block and artificial stone.

New Jersey. — Basalt quarrying is an important industry in New
Jersey, the State usually ranking first in the country. Trap rock, which
forms the famous palisades along the Hudson River, extends westward
and appears in most counties of northern New Jersey. Quarries farthest
south are near Moore, Pennington, and other points along the Delaware
River, Mercer County; and at Lambertville, Hunterdon County. One

CRUSHED STONE OTHER THAN LIMESTONE 485

of the largest quarries in eastern United States is at Bound Brook,
Somerset County. Other important operations in this county are at
Milhngton, North Plainfield, Scotch Plains, and Westfield. Very large
crushing plants are located at Summit, Union County; and at North
Bergen, Hudson County. Extensive activities at South Orange, West
Orange, and North Caldwell supply the populous centers of Essex
County. At least 10 large quarry companies were operating in Passaic
County in 1930; the chief centers are Richfield, Great Notch, Little
Falls, Hawthorne, Clifton, and Paterson, Quarrying at various points
along the palisades of the Hudson River in Bergen County has been
discontinued, because it detracts from the scenic beauty of the river;
but one large quarry is still operated at Cliffside Park.

Rock approaching a granite in composition is quarried near Pompton
Lakes, Morris County, and sandstone is utilized as riprap in Hunterdon
County. Argillite (a firmly consoHdated, massive shale), which is
employed extensively for local building purposes at Princeton, Mercer
County, is also crushed for use as concrete aggregate.

New Mexico. — Crushed sandstone for railroad ballast is obtained
from a large quarry in Socorro County near SchoUe. A large plant was
under construction in 1932 near Santa Rosa, Guadalupe County, for
production of asphaltic sandstone to be used in highway work. A rock
known as "cahche," a form of earthy limestone characteristic of arid
regions in the Southwest, is quarried for road building in Mora County.

New York. — Basalt is quarried extensively in Rockland County,
New York, in a northward extension of the palisade trap rock of New
Jersey. One of the largest quarries for production of crushed stone in
eastern United States is at Haverstraw, and there are other large quarries
at West Nyack and Suffern.

Granite is quarried in several counties in eastern and southeastern
New York. Road stone is produced in Westchester County near New
York. Farther north along the Hudson River crushed granite is prepared
for use at a large quarry near West Point, Orange County, and riprap is
produced in Washington County as occasion demands. Granite is
crushed for road building at Altamont, Albany County. One of the
largest quarries in the State for production of crushed granite is at Little
Falls, Herkimer County. Other quarries are in Hamilton County; at
Ehzabethtown, Keene, Keesville, and Lake Placid, Essex County; and at
Alexandria Bay, Jefferson County.

Sandstone is quarried in many parts of New York. Rock, some of
which is red and useful for surfacing private roads and walks, is quarried
at Central Valley, Thompson Ridge, and other points in Orange County.
Bluestone is crushed for road stone and riprap in Sullivan County.
Sandstone, used principally for road stone, is quarried at Greensville,
Greene County; New Salem, Albany County; and Schenectady, Sche-

486 THE STONE INDUSTRIES

nectady County. Other quarries are at such widely separated locahties
as Steuben County in south-central New York and Oswego County near
the eastern end of Lake Ontario. The Medina sandstone, which is
utilized extensively for the manufacture of paving blocks and curbing, is
crushed for road base and concrete aggregate at Albion and other places
in Orleans County and at Lockport, Niagara County.

North Carolina. — Granite, the most important source of crushed stone
in North Carolina, is utilized in many western and northern counties.
Developments of importance farthest west are in Buncombe County,
chiefly at Asheville and Swannanoa. Large quarries are worked at
Hiddenite, Alexander County; at Winston-Salem, Forsyth County; and
at Charlotte, Mecklenburg County. Concrete aggregate and railroad
ballast are manufactured at Mount Airy in Surry County as by-products
of the extensive building-stone, paving-stone, and curbing industry
centered in that locality. Granite Quarry and Salisbury, Rowan County,
are important sources of crushed granite. Large quarries are worked in
several north-central counties. The principal centers are Stacey,
Rockingham County; Stokesdale, Guilford County; Chapel Hill, Orange
County; Greystone, Vance County; Wake Forest, Wake County; and
Sims, Wilson County. Crushed stone classed in the miscellaneous group
is quarried near Durham, Durham County.

Ohio. — Rocks other than limestone occurring in Ohio are of little
importance for crushing compared with the enormous limestone resources
of the State. The extensive block-sandstone industries of Amherst,
Lorain County, and Euclid, Cuyahoga County, produce considerable
sand as a by-product. It is used as building sand and in foundries and
steel mills. The building-sandstone industry at McDermott, Scioto
County, produces riprap as a by-product. Sandstone has been quarried
for concrete-aggregate manufacture in Athens and Tuscarawas Counties.
Rock classed in the miscellaneous group is crushed at Mifflin and Jeromes-
ville, Ashland County, and boulders are crushed for road stone and
concrete aggregate in Clermont County.

Oklahoma. — Crushed granite and riprap are produced at Granite,
Greer County, and crushed sandstone has been produced in Coal County.
Asphaltic sandstone of Ordovician age is quarried near Dougherty,
Murray County. A bituminous limestone obtained near the same
locality is mixed with the sandstone and the mixture used for highway
and street paving.

Oregon.— Basalt is abundant and widely used in Oregon, chiefly in
the western counties. It is an important source of raw material for high-
way construction throughout the western third of the State and also in
Wallowa County, in the northeastern corner. Oregon is characterized by
a large number of small or moderate-size quarries, the aggregate annual
production of which is in times of normal prosperity valued at about

CRUSHED STONE OTHER THAN LIMESTONE 487

$1,500,000. In the following brief outline of quarry centers, many
regions having relatively small production are omitted.

In the northwestern corner of the State basalt is quarried at Jewell
and Astoria, Clatsop County; and at Mist, Clatskanie, Saint Helens
and other places, Columbia County. Riprap is an important product in
the latter locality. Other quarry centers in the northwestern area are
Blaine and other points in Tillamook County; Hillsboro and Reedville,
Washington County; Yamhill and Gaston, Yamhill County; Portland
and vicinity, Multnoma County; Barlow, Clackamas County; Albany,
Brownsville, and Holley, Linn County; Alsea and Corvallis, Benton
County; The Dalles, Wasco County; and Wasco, Sherman County.
Many basalt quarries are or have been worked in southwestern Oregon,
principally at Ashland and Eagle Point, Jackson County; Crater Lake
and Klamath Falls, Klamath County; Yoncalla and Drain, Douglas
County; and Mapleton, Paris, Alma, and several other localities in Lane
County. In Wallow^a County, in the northeastern corner of the State,
basalt is quarried at times at Lastine, Flora, and Wallowa.

Sandstone is quarried as occasion demands for highway work and con-
crete aggregate in Coos and Washington Counties. Immense quantities
of sandstone riprap for breakwaters are quarried at Marshfield, Coos
County; Reedsport, Douglas County; and Florence, Lane County. A
number of both basalt and sandstone quarries are temporary in character,
operating only a year or two to supply stone for special projects.

Pennsylvania. — Sandstone and quartzite are the most important rocks
other than limestone used in crushed or broken form in Pennsylvania.
Large quantities of basalt are quarried, while granite and miscellaneous
rocks are utilized in smaller amounts.

Basalt or trap rock is confined to the southeastern part of the State.
Large, well-equipped quarries producing thousands of tons of crushed
stone for railroad ballast, concrete aggregate, and highway construction
are located at Glen Mills, Delaware County; Quakertown and Rockhill,
Bucks County; and Birdsboro, Berks County. Other basalt quarries
are at Elizabethtown, Lancaster County, and at several points in Mont-
gomery County. Roofing granules are manufactured extensively from
basalt and other igneous rock at Greenstone and near Charmian, Adams
County.

Granite of present commercial importance is restricted in occurrence
to the extreme southeastern corner of the State. Much so-called granite
is banded and therefore more correctly classified as gneiss. One of the
more important quarry centers is at Glenmoore, Chester County, but
substantial amounts are obtained in Philadelphia, Delaware, Montgomery,
and Berks Counties.

Large amounts of sandstone are produced for riprap and ordinary
crushed-stone uses, while in production of ganister, a form of quartzite,

488 THE STONE INDUSTRIES

Pennsylvania leads all States by a wide margin. Sandstone-crushing
plants are scattered widely throughout the State. In directing attention
first to eastern activities mention may be made of quarries producing
riprap and concrete aggregate at Lumberville and Neshaming Falls,
Bucks County, and also in Berks and Dauphin Counties. Both basalt
and granite are of much greater importance than sandstone as sources of
crushed stone in the southeastern counties. In northeastern Pennsylvania
sandstone is quarried in Pike County; at Scranton, Lackawanna County;
and at Wilkes-Barre, White Haven, Hendler, and other points in Luzerne
County. The crushed-sandstone industry of east-central Pennsylvania
is represented by quarries at Dalmatia and Shamokin, Northumberland
County, and by small road-stone quarries in Lycoming County. In the
central area large quarries are operated for railroad ballast and concrete
aggregate production at Williamsburg, Blair County; and at Water
Street, Huntingdon County. A small output of crushed sandstone has
been reported in Indiana County in west-central Pennsylvania, and
quite extensive operations are conducted at Connellsville, Dunbar, and
Coolspring, Fayette County; and at McCance and Torrance, Westmore-
land County.

Canister is quarried most extensively in central Pennsylvania,
although considerable quantities are obtained in other parts of the State.
"Floe" rock, occurring chiefly at high levels in the mountains and
consisting of talus-slope boulders, is obtained in great quantities at
Williamsburg, Claysburg, Flowing Spring (post office. Canoe Creek),
Sproul, and McKee, Blair County; Alexandria, Barree, Mount Union,
Water Street, and Neelyton, Huntingdon County; Port Matilda, Center
County; and Lewistown, Mifflin County. Canister is quarried at
Columbia, Lancaster County, in southeastern Pennsylvania; Layton,
Fayette County, in the southwest; and New Castle, Lawrence County,
near the western border. A small supply is obtained at times in Indiana
County.

One of the most important of the miscellaneous rocks is mica schist
quarried chiefly for furnace lining at Edge Hill, Glenside, and other points
in Montgomery County. Argillite is quarried at Perkiomenville and
Sanatoga in the same county; near Gettysburg, Adams County; and at
many places in Berks County. Serpentine is crushed for terrazzo
manufacture at Quarryville, Lancaster County. Immense quantities of
boulders and other miscellaneous varieties of stone were produced in
numerous wayside quarries for secondary road construction during 1932.

Rhode Island. — Crushed granite is produced as a by-product of a
granite dimension-stone industry at Bradford near Westerly in the
southwestern corner of Washington County. Granite is quarried and
crushed at Bristol, Bristol County, and at Newport and other points in
Newport County. A conglomerate rock is also quarried near Newport.

CRUSHED STONE OTHER THAN LIMESTONE 489

Serpentine rock is crushed for road building at Cranston and Providence,
Providence County. Rock, designated by some as trap, also occurs in
this county and is quarried at Berkeley, Diamond Hill, and Woonsocket
for use as concrete aggregate and road stone.

South Carolina. — Granite is the only rock used for the manufacture
of crushed and broken-stone products in South Carolina. The larger
operations are in the central and western parts of the State. The
quarry of largest output in northeastern South Carolina is at Pageland in
northern Chesterfield County. Large, productive quarries are located
in an area near the center of the State. The more important are at
Blairs, Fairfield County; Columbia, Richland County; and Cayce,
Lexington County. While crushed stone is the chief product a minor
output of riprap is reported from this district. Except for a quarry of
major proportions at Trenton, Edgefield County, near the western
border of the State, chief activity outside the central district is in the
extreme northwest. Large quarries for production of road stone and
concrete aggregate are at Liberty, Pickens County, and at Hellams,
Greenville County, while smaller quarries are worked in Oconee and
Spartanburg Counties.

South Dakota. — Granite quarried at Rapid City, Pennington County,
is used as crushed stone and also for filter beds in sewage plants. Sand-
stone is quarried for road construction and concrete aggregate in Hanson
County; and at Dell Rapids and Sioux Falls, Minnehaha County.
Canister for furnace lining and furnace sand is obtained in both the last-
named localities. Rock classed as porphyry is used as a source of crushed
stone at Lead and other points in Lawrence County.

Texas. — Prominent rounded knobs of trap rock stand out prominently
on the plains of Uvalde County, in southern Texas. They are quarried
extensively at Knippa, chiefly for railroad ballast. Riprap is produced
near Marble Falls, Burnet County, in central Texas, as a by-product of a
building and monumental granite industry. Sandstone is quarried for
breakwaters at Huntington, Angelina County; and for both riprap and
roadstone near Huntsville, Walker County.

The principal Texas rock classed in the miscellaneous group is
"caliche" which is quarried at Skidmore, Bee County; and at ReaUtos,
Duval County, in southern Texas; also in El Paso County and at Alla-
moore, Hudspeth County, in the far west. Rock of uncertain type is
used for road construction at Pittsburgh, Camp County. Volcanic tuff
is quarried in Martin County and unclassified rock at Mathis, San
Patricio County. Portable crushing plants are operated in various
counties, as occasion demands.

Utah. — Asphalt-bearing sandstone of Eocene age is quarried in the
Book Cliffs near Sunnyside, Carbon County. Stone is lowered 3,000
feet over a 3-mile tramway to a terminal base in Whitmore Canyon.

490 THE STONE INDUSTRIES

It is crushed at Sunnyside and shipped by rail for road-building purposes.
Rock classed in the miscellaneous group is manufactured into roofing
granules in Salt Lake County.

Vermont. — Although Vermont produces very large quantities of
monumental granite the output of crushed material is quite small. One
of the large companies producing dimension stone at Websterville,
Washington County, crushes granite waste and markets it as a by-
product. Small amounts of crushed granite and riprap for railroad use
are produced at other quarries in this county. At West Dummerston,
Windham County, and Bethel, Windsor County, a small part of the
waste at block-granite quarries is crushed for concrete aggregate and
road stone.

Virginia. — Trap rock is sometimes quarried in eastern Loudoun
County near Ashburn. Crushed granite is produced near Culpepper,
Culpepper County, and in Albemarle County. Large quarries are
operated for production of railroad ballast, road stone, and concrete
aggregate near Richmond, Henrico County; and at Boscobel, Goochland
County. The largest granite quarry in the State, at Skippers, Greens-
ville County, produces many thousands of tons of railroad ballast.
Sandstone is crushed in southern Augusta County near Waynesboro,
and there are small quarries in Bath and Highland Counties in west-
central Virginia.

Washington. — Basalt, chiefly of Tertiary age, is a very important
source of crushed stone in Washington. The rock is distributed very
widely and quarried in more than 20 counties. In southeastern Wash-
ington crushed basalt is produced in Asotin, Garfield, and Franklin
Counties; at Dayton, Columbia County; at Lamar, Walla Walla County;
at Pullman, Penawawa, RosaHa, Palouse, Colfax, and Colton, Whitman
County; and at Prosser, Benton County. Spokane County, in eastern
Washington, is an important producer, with quarries at Rockford, Plaza,
Medical Lake, Fairfield, and Mead. Pond Oreille County in the north-
east, Okanogan County in the north, and Kittitas and Grant Counties
in the central area are moderate producers. Both riprap and crushed
stone are produced at North Bend and other points in King County; at
Charleston, Kitsap County; and in Pierce County, in the west-central
region. There are numerous quarries in southwestern Washington.
Some of the active centers are Long Beach, South Bend, and Seaview,
Pacific County; Doty and Divide, Lewis County; and Stella, Cowlitz
County. Yakima, Yakima County, and Goldendale, Klickitat County,
are production centers in southern Washington. Some quarries are
temporary, operating for only a year or two to supply stone for special
projects.

Granite quarrying is confined to an area near the center of the State
where small to moderate-size quarries are operated at Lakeside and

CRUSHED STONE OTHER THAN LIMESTONE 491

Entiat, Chelan County, and in southern Douglas County near Trinidad
and Wenatchee. Sandstone occurs in west-central and northwestern
Washington. A little riprap is produced at Wilkeson, Pierce County,
as a by-product of a cut-stone industry. A total production of some
magnitude is obtained from the operation of portable crushers scattered
throughout various counties.

West Virginia. — Sandstone is the only rock other than limestone used
for crushing in West Virginia. Normally the most important sandstone
activity is the production of ganister at Berkeley Springs, Morgan
County. Concrete aggregate and road stone are produced at Charleston,
Kanawa County, and in Ohio County. Several sandstone quarries are
operated intermittently by the State.

Wisconsin. — The only important trap-rock-quarry region in Wisconsin
is at Dresser Junction, Polk County, on the western border. Minneapolis
and St. Paul, Minn., are important markets for the products of stone
crushers in this territory. Crushed or broken granite is produced
principally in the regions where monumental stone, building granite,
and paving blocks are manufactured, and much of it is a by-product of
these industries. Riprap and crushed granite are quarried at Lohrville
and Redgranite, Waushara County, and to a smaller extent in Green
Lake and Juneau Counties. Small quantities of sandstone riprap
constitute part of the output of Dunn County as a by-product of a
building-sandstone industry. Quartzite (ganister) for manufacture of
silica brick and furnace linings is produced near Ableman, Devils Lake,
and North Freedom and crushed quartzite for road work at Ableman and
Baraboo, all in Sauk County, in southern Wisconsin. The Baraboo
quartzite is also used for the manufacture of granules. Crushed stone,
classified in the miscellaneous group, is quarried for highway construc-
tion in Wood County.

Wyoming.— Sandstones occurring in Carbon and Platte Counties are
crushed for road building and concrete aggregate.

QUARRY METHODS AND EQUIPMENT

Methods of quarrying and preparing limestone for various markets
have been described in some detail in the preceding chapter. For types
of rock other than limestone the general procedure differs in no material
respect, therefore repetition of the various steps is unnecessary. Atten-
tion will be directed merely to certain differences between limestones
and other rocks and the influence these differences exert on equipment
and methods.

Granites and trap rocks are much harder than limestones. Depend-
ing upon their degree of cementation, some sandstones are also much
harder than average limestone, while others work quite easily. Drilling
in any of the harder varieties of rock is slower than in limestone, and the

492 THE STONE INDUSTRIES

drill steel wears rapidly, therefore drilling costs are comparatively high.
Heavy charges of dynamite are required for the tougher varieties.

Crushing equipment must ordinarily be sturdier than that for lime-
stone. The abrasive action of the more siliceous stones wears out the
contact parts of crushers, screens, and elevators rather rapidly.

For these reasons quarry costs are generally somewhat higher for
siliceous rocks than for limestone. According to a report on quarry
costs prepared by Thoenen,^^ average direct costs, including crushing
and screening, are 75 cents a ton for trap rock, $1.08 a ton for granite,
and 97 cents a ton for sandstone compared with an average limestone
quarrying and crushing cost of 56 cents a ton. These are general
averages and include quarries of all sizes. Operators of the larger and
more completely equipped quarries may reduce costs somewhat below
average figures, while smaller and less completely mechanized plants
may have somewhat higher costs.

As pointed out in the introductory part of this chapter, waste lime-
stone finds much wider use than waste stone of other types. Therefore,
for quarrying and crushing rocks other than limestone efforts are directed
toward obtaining explosives and equipment best-adapted for preparing a
high proportion of marketable sizes, with a minimum of fines.

MARKETING
Marketing problems differ in no essential respect from those of lime-
stone. Trap rock has a high reputation for road construction and finds
its best market in that field. Granite is used less widely in highways
but is employed in large quantities for concrete aggregate, railroad
ballast, and riprap. Sandstone also is marketed most extensively for the
last uses, although it is used to some extent for road base. Miscellaneous
rocks enter many fields of utilization, which are so diversified that no
general statements may be made regarding the scope of their markets.

Bibliography
Bowles, Oliver. Sandstone Quarrying in tlie United States. Bur. of Mines Bull.

124, 1917, 143 pp.
Coons, A. T. Chapters on Stone, Mineral Resources of the United States. Pub-
lished annually by Bur. of Mines (U. S. Geol. Survey prior to 1924, Minerals

Yearbook since 1931).
Landes, Henry. The Road Materials of Washington. Wash. Geol. Survey Bull. 2,

1911, 204 pp.
Moore, E. S., and Taylor, T. G. The Silica Refractories of Pennsylvania. Topog.

and Geol. Survey of Pennsylvania Bull. M-3, 1924, 100 pp.
Newland, D. H. The Quarry Materials of New York — Granite, Gneiss, Trap,

and Marble. New York State Museum Bull. 181, 1916, 212 pp.
Thoenen, J. R. Study of Quarry Costs — Trap Rock, Sandstone, Granite. Bur. of

Mines Inf. Circular 6291, 1930, 24 pp.

'2 See bibliography at end of chapter.

INDEX

"A. S. T. M. Standards, 1927," 156
Abrasion, effect on stone, 355
Abrasives, for sawing, use, 93

scrubbing with, for cleaning stone, disad-
vantages, 364
Acids, for cleaning stone, disadvantages, 364
Adobe method, of blistering, description, 459
Africa, marbles of, 330
sandstone of, 311

(See also Algeria; Egypt; Morocco; Union of
South Africa)
Agalmatolite, deposits of, 342

uses, 342
Agricultural limestone, production, 391

use, 391
Alabama, bituminous rock sold in, data, 482
Blount County, limestone of, uses, 396
Calhoun County, quartzite production, use in

brick, 477
Cherokee County, quartzite production, use

in brick, 477
Colbert County, oolitic limestone of, uses, 398
Covington County, limestone of, uses, 398
crushed-limestone industry, 396
crushed sandstone sold in, 476
crushed-stone industry, 477

Etowah County, limestone of, use as iron-
furnace flux, 396
Franklin County, Bangor limestone of, 37

limestone of, use as iron-furnace flux, 396
Jackson County, limestone of, 398
Jefferson County, ganister production, use in
brick, 477
limestone of, uses, 396
limestone of, description, 37, 396
marble of, description, 200

production data, 200
Marengo County, chalk beds of, uses, 398
St. Clair County, limestone of, use for cement,

396
Shelby County, limestone of, use for lime, 396

"Variegated Marbles Southeast of," 226
Talladega County, niarble of, use as furnace
flux, 398
marble quarries, 200
Washington County, limestone of, uses, 398
"Alabama, Crystalline and Other Marbles of,"

200, 228
"Alabama, Index to the Mineral Resources of,"

472
Alabaster, deposits of, 342

uses, 342
Alaska, Dall Island, limestone production, 448
marbles, 203

"Alaska, Southeastern, Marble Resources of,"

203, 226
Algeria, onyx marbles of, 332
Alkali, manufacture, 391
Alteration, of minerals, effect on stone, 350
Aluminum, as substitute for stone, utilization, 9
Amazon stone (see Amazonite)
Amazonite, deposits of, 343
American Society for Testing Materials, 358

{See also "A. S. T. M. Standards, 1927")
Ammonium chloride, as solvent, effect, 350
Ammonium sulphate, as solvent, effect, 350
Anatolia, meerschaum of, 345
Anderegg, F. O., 65, 358
Architectural slates, manufacture, 271
Argentina, fluorite of, 344
marbles of, 331
onyx marbles of, 332
Argillite, definition, 485

(See also Arkansas, Pulaski County; New
Jersey, Mercer County; Pennsylvania,
Montgomery County)
Arizona, Apache County, fossil wood of, 346
sandstone of, use as riprap, 477
Cochise County, cretaceous limestone of, uses,
398
quartzite of, use as furnace lining, 477
crushed granite sold in, 475
crushed-limestone industry, 398
crushed sandstone sold in, 476
crushed-stone industry, 477
Gila County, decomposed granite of, 477

metallurgical lime of, 398
malachite of, 345

Maricopa County, crushed-gravel production,
477
fluxing limestone of, 398
onyx marbles of, 204
onyx marbles of, 204
Pima County, lime plant, 398
Pinal County, caliche production, 477
State Capitol, construction, 142
volcanic tuffs of, 142

Yavapai County, limestone of, uses, 398
onyx marbles of, 204
"Arizona, Mineral Industries of," 228
Arkansas, Baxter County, marble of, 204
crushed-limestone industry, 399
crushed sandstone sold in, 476
Garland County, novaculite of, 73
Howard County, limestone of, 399
Independence County, lime plants, 399

marbles of, 204
Izard County, lime plants, 399

marble of, quarrying, use of wire saw, 204
Little River County, chalk of, uses, 399

493

494

THE STONE INDUSTRIES

Arkansas, marbles of, 204

Montgomery County, slate of, 251

Polk County, slate of, 251

Pulaski County, argillite production, 478

Searcy County, lime plants, 399

Sebastian County, sandstone production, 478

Sharp County, limestone of, uses, 399

Washington County, lime plants, 399
"Arkansas, Northern, Black Marbles of," 228
"Arkansas, Slates of," 289
Arkose, definition, 67
Armstrong, W. D., 19
Ashlar, definition, 24

laying, diagram, 24
Ashley, G. H., 65
Asia, marbles of, 331
Asphalt filler, preparation, 385
Asphaltic rock (see Bituminous rock)
Aubury, Lewis E., 102, 167, 203, 226, 288
Australia, malachite of, 345

marble of, 331

slate of, 340
Austria, marbles of, 329
Azurite, description, 345

Ballast (see Railroad ballast)
Bangor district (see Pennsylvania)
Bangor limestone (see Alabama)
Bar drills, description, 145

use, 84
Barre granite (see Vermont, Washington County)
Basalt, crushed, bibliography, 492

industry by states, 477

marketing, 492

production, 371, 477

quarry costs, 492

quarry methods, 491

uses, 474
Bath stone (see England, Wiltshire, limestone

deposits)
Bayley, W. S., 194, 226
Baylor, H. D., 470
Bays Mountain belt (see Tennessee)
Bedford-Bloomington district (see Indiana,

limestone of)
Bedford limestone (see Indiana, limestone of)
Beede, J. W., 65

Beer stone (see England, Devonshire)
Behre, C. H., Jr., 142, 288, 368
Belfast-Edelman district (see Pennsylvania)
Belgium, limestone of, 306

marbles of, 325

quarrying methods, 326

slate of, 338
Berkey, C. P., 97, 98
Bermuda, limestone of, 303
Berry, E. W., 471

" Birdseye " marble, deposit of, 206
Bituminous rock, sales data, 482
Black marble, deposits of, 194, 202, 204, 205, 206,

323, 324, 326, 328, 329, 330
Black Oak belt (see Tennessee)
Blackboards, type of slate needed for, 235
Blagore, G. H., 323

Blanket shooting, description, 458
Blasting methods (see various stones discussed)
Blavier method, for mining slate, description, 337
Bleininger, L. V., 470
Blistering, description, 459

Blockholing method, of blistering, description, 459
Blow torch, heating with, disadvantages, 363
Blue John, use for ornaments, 344
Blue marble, deposits of, 324
Bluestone, commercial types, 99
composition, 97
definition, 97
durability, 98
finishing, trimming, 100
as flagging, use, 71
industry, discussion, 97
marketing, 101
quarrying, equipment, 99
methods, 99
splitting beds, 100
structure, 97
uses, 98
Bolin, D. C, 470
Bonewits. E. E., 228
Boulder quarries, 186

(See also Vermont, granite of, block quarries)
Boulders, in buildings, use, 296, 299
view, 300
origin, 296
view, 300
Bowles, Oliver, 19, 102, 114, 167, 181, 226, 227,

286, 288, 295, 340, 376, 470, 492
Bownocker, J. A., 81, 102, 470
Breccia, imports, table showing, 225
Briar Hill stone (see Ohio)
Brightly, H. S., 368

"British and Foreign Marbles and Other Orna-
mental Stone," 228, 341, 347
"British Slates, Quarrying and Mining of," 341
Broaching, definition, 145
Brownsville district (see Maine, Piscataquis

County)
Brush Mountain stone (see Virginia, Montgomery

County)
Buckley, E. R., 28, 167, 198
Buehler, H. A., 167, 198, 470
Buffer, for finishing marble, description, 220

view, 220
Buffer shooting, description, 458
Buhrstone, use as millstone, 71
^uilding stone, classes, 23
durability, 30
foreign, discussion, 301
types, 23
"Building Stone, Prevention of the Decay of,"

368
"Building Stones and Clays," 102, 167, 227, 228.

288, 289
"Building Stones; Their Properties, Decay, and

Preservation," 2^8, 341, 349, 353, 368
"Building Stones, Weathering of," 368
"Building Stones, Weathering of Natural," 368
Bulgaria, marbles of, 329
Bull sett, definition, 159
Bulldozing, description, 459
Burchard, E. F., 203, 226

INDEX

495

Burfoot, J. D., 295
Butts, Charles, 226

Caen stone {see France, Normandy)
Calcium carbide, manufacture, 392
Caliche, definition, 477
California, Alameda County, lime plant, 400

sandstone quarrying, 478
Amador County, marbles of, 203
basalt sold in, 477
bituminous rock sold in, data, 482
Butte County, crushed-stone industry, 479
Calaveras County, cement manufacture, 400

trap rock of, use in roofing granules, 478
Colusa County, sandstone of, 73
Contra Costa County, crushed-stone industry,
478

limestone of, uses, 400, 401
crushed granite sold in, 475
crushed-limestone industry, 399

production data, 400
crushed-stone industry, 478
crushed sandstone sold in, 476
Del Norte County, crushed-stone industry, 478,

479
diatomite of, 344
El Dorado County, limestone of, uses, 400, 401

slate of, 251
Fresno County, crushed-stone industry, 479

monumental granite of, 137
granite of, description, 137

production data, 137
Humboldt County, crushed stone of, use in

road building, 480
Imperial County, granite of, 137
Inyo County, dolomitic marble of, 202, 401

volcanic tuff of, 479
Kern County, crushed-stone industry, 479

limestone of, uses, 400, 401
Lake County, basalt production, 478
lapis-lazuli of, 345
Lassen County, crushed stone of, use in road

building, 479
Los Angeles County, arkose sandstone of, 73

cement manufacture, 400

crushed-stone industry, 479
Madera County, granite of, 137
marbles of, 202

production data, 202
Marin County, sandstone quarrying, 478
Merced County, cement manufacture, 400
Mono County, travertine of, 44, 401
Monterey County, argillaceous sandstone of, 73
Napa County, basalt production, 478
Nevada County, granite of, 137
Placer County, granite of, 137

limestone of, 400
Plumas County, monumental granite of, 137
Riverside County, cement manufacture, 400

granite of, 137
Sacramento County, building granite of, 137

crushed-stone industry, 479
San Benito County, cement manufacture, 400

granite of, use as crushed stone, 478

California, San Bernardino County, crushed-stone
industry, 478, 479

limestone of, 203, 400, 401
San Diego County, felsite porphyry of, 479

granite of, 137
sandstone of, 73
San Francisco County, crushed-stone industry,

478
San Mateo County, cement manufacture, 400

crushed-stone industry, 478
Santa Barbara County, crushed-stone industry,
478, 479

sandstone of, 73
Santa Clara County, basalt production, 478

limestone of, uses, 401

sandstone of, 73
Santa Cruz County, bituminous sandstone of,
479

limestone of, uses, 400
Shasta County, crushed stone of, use in road
building, 480

limestone of, uses, 400, 401
soapstone of, 291
Solano County, basalt production, 478

cement manufacture, 400

onyx of, 203
Sonoma County, basalt production, 478
Stanford University, sandstone used for, 73
Stanislaus County, crushed-stone industry, 479
Trinity County, crushed stone of, use in road

building, 480
Tulare County, granite of, 137
Toulumne County, limestone of, uses, 400, 401

marbles of, 203

slate of, 251
Ventura County, sandstone of, 73
volcanic tuflf of, 142
"California, Carmel Valley, Geology of Building

Stone from," 102
"California, Structural and Industrial Materials

of," 102, 167, 203, 226, 288
California State Mining Bureau, 227
Canada, British Columbia, jade of, 345

marbles of, 318
granite of, 311

imports, 166
labradorite of, 345

"Limestones of Quebec and Ontario," 340
Manitoba, limestone of, 302
Maritime Provinces, granite of, 311

sandstone of, 309
microcline of, 343
Ontario, granite of, 311

limestone of, 303

marbles of, 317

sandstone of, 309

sodalite of, 347
Prairie Provinces, granite of, 312

sandstone of, 309
"Quarrying and Dressing Stanstead Granite,"

340
Quebec, granite of, 312

marbles of, 317, 318

slate of, 333

soapstone of, 292

496

THE STONE INDUSTRIES

Canada, War Memorial, at Vimy Ridge, con-
struction, 330
"Canada, Building and Ornamental Stones of,"

29, 169, 227, 340
"Canadian Limestones for Building Purposes,"

340
Carbon dioxide from lime kilns, possible uses, 394

as solvent, effect, 349
" Carbonic Acid Tests on Weathering of Marbles

and Limestones," 227
Carborundum, rubbing with, disadvantages, 363
Carborundum saws, use for cutting limestone, 58
Carborundum wheels, use for machining marbles,

221
Cars, for transporting sandstone, description, 93

trackage, arrangement, 94
Carthage district (see Missouri)
Catlinite, deposits of, 344
(See also Minnesota)
Caustic soda, for cleaning stone, disadvantages,

364
Cement, manufacture, description, 385

diagram, 386
"Cement, Story of," 470

Cement-plant quarries, methods, description, 469
Cement rock, as raw material for cement, 387
Central America, marbles of, 331
Chalk, composition, 34
preparation, 383
use of limestone as, 381
"Chalk, Whiting, and Whiting Substitute," 470
Channeling, definition, 148
Chapman Quarries district (see Pennsylvania)
Chase saw, use, 161

Chemical reactions, effect on stone, 349
Chicken grit (see Poultry grit)
Chile, lapis-lazuli of, 345
marbles of, 331
onyx marbles of, 332
China, agalmatolite of, 342
Choke feeding, avoidance, 465
Churn drills, use in crushed-limestone quarries,

453, 454
Cipolin marbles, deposits of, 317, 325, 327, 330
Circular saws, use, 161
Clarendon district (see Vermont)
Clay, uses as building material, 344
Cleaning methods, for stone, discussion, 362
Coal mines, dusting, use of limestone for, 381
Cocalico stone (see Pennsylvania, Lancaster

County)
Cole, L. H., 340
Colombia, marble of, 331
Color, importance, 27
Colorado, basalt of, 480

Boulder County, sandstone quarrying, 480
Chaffee County, limestone of, uses, 402
quartz diorite of, 142
travertine of, 44
crushed granite sold in, 475
crushed-limestone industry, 401
crushed sandstone sold in, 476
crushed-stone industry, 480
El Paso County, limestone of, uses, 402
Manitou Green-Stone of, 37
phonolite of, 480

Colorado, Fremont County, limestone of, usee,
402
monumental-granite production, 142
sandstone quarrying, 480
travertine of, 44
granite production, 142
Gunnison County, marble of, 204
Jefferson County, granite quarry, 480
Lake County, limestone of, use, 402
La Plata County, limestone of, uses, 402
Larimer County, limestone of, uses, 402
Las Animas County, crushed-stone plant, 480
limestone of, 37

use for refining beet sugar, 392
marbles of, 204
microcline of, 343
Pueblo County, lime plants, 402
sandstone of, 73
quarrying, 480
Routt County, volcanic tuff of, 480
Teller County, phonolite production, 480
"Commodity Specifications, National Directory

of," 379
Compressed air, forcing sheeting planes with, 150

use for quarry drilling, 84
Compressed-air tools, adoption, 60
Concord belt (see Tennessee)
Concrete aggregate, requirements, 379

use for building purposes, 378
Concrete block aggregate, use, 384
Concrete block facing, use, 384
Conglomerate, definition, 67
Connecticut, basalt sold in, 477
crushed granite sold in, 475
crushed-limestone industry, 402
crushed sandstone sold in, 476
crushed-stone industry, 480
Fairfield County, magnesian limestones of, 403

trap-rock quarries, 480
granite of, 139

production data, 139
Hartford County, granite of, 139

trap-rock quarries, 480
limestone of, 402

Litchfield County, dolomites of, use for lime, 402
Middlesex County, sandstone of, 73

production, 480
New Haven County, granite gneiss of, 139

trap-rock quarries, 480
New London County, granite of, 140
Portland brownstone of, 74
sandstone of, 73

Windham County, granite of, 140
Consolidating processes, discussion, 361
Contraction, effect on stone, 353
Cooke, C. Wythe, 470
Coons, A. T., 167, 288, 470, 492
Copper stains, removal, 367
Coquina, composition, 34

deposits, 37, 403
Coral, composition, 34
Cordeau detonating fuse, use, 459
Core drilling, advantages, 11

Costs, crushed-limestone production, by quarry
methods, 467
by underground mining, 468

INDEX

497

Costs, crushed-stone quarrying, 492
granite quarrying, 156
limestone quarrying and milling, 63
Cox, A. W., 471

Coyote-hole blasting, description, 456
Crider, A. F., 470
Crinoid limestone, composition, 34
"Crowfoot structure," definition, 186
Crushed limestone, bibliography, 470
competitors, 373
crushing, 464
elevating, methods, 465
fine grinding, 466
industry, operating costs, 467
marketing, 374
mining methods, costs, 468

description, 467
prices, 375
production, quantity sold, graph, 372

table, 371
quarry cars, discussion, 463
quarrying methods, 373, 452
blasting, 455
drilling, 453
haulage, 461
by trucks, 464
trackage, 462

computation, 463
views, 460, 462
loading, 459
diagram, 461
views, 460, 462
plan, 452
royalties, 375
screening, 465
storage, 466
transportation, 374
uses, 373
washing, 465
Crushed stone, bibliography, 492
crushing equipment, 492
industries, capital required, 375
discussion, 371
by states, 477
marketing, 492

production, data, 473, 474, 475, 476, 477
quarrying methods, 470, 491

costs, 492
sources, distribution, 474
uses, 3, 473
Crushed Stone Journal, 470
" Crushed Stone Production, Economics of,

376, 470
Cuba, limestone of, 303

marbles of, 318
Curbing, manufacture, 95, 155

stones used for, 26
Cushman, J. A., 471
Czechoslovakia, meerschaum of, 346

Darton, N. H., 227
Davies, D. C, 340
Decker, C. E., 433
Delaware, crushed granite sold in, 475

crushed-stone industry, 480

limestone of, 403

monumental granite of, 142

Newcastle County, crushed-stone production,
480
Delcourt, E., 338

Derby gray (see Vermont, Orleans County)
"Developing a Quarry," 19

Development work, undertaking, factors govern-
ing, 11
Diamond core drills, description, 12
Diamond saws, for cutting limestone, use, 57

for finishing marble, use, 220
view, 221
Diatomite, use as building material, 344
Dikes, definition, 109
Dimension stone, adaptation to use, 30

color, 27

composition, 26

definition, 23

hardness, 27

industries, discussion, 23

marketing, complexities, 31

physical properties, summary, 29

porosity, 28

requirements, 26

royalties on, computation, 31

specific gravity, 29

strength, 28

texture, 27

uses, 23
history, 3

weight per cubic foot, 29
District of Columbia, granite gneiss of, iises, 480

Lincoln Memorial, construction, 172, 205, 222

Patent Ofiice, sandstone for, source, 79

Post Office, construction, 116

Union Station, construction, 116
plaza, fountains, construction, 118

United States Capitol, construction, 79, 181

Washington Monument, strength, 28

White House, sandstone for, source, 79
Ditcher, use for circular scabbling, 85
Dolomite, definition, 33

in marble, undesirability, 177

uses, 394

weathering efiPects, 359
Dorset Mountain district (see Vermont)
Dragline scraper, for stripping, 15
Drill holes, arrangement, 12, 86, 458
diagram, 87
results, views, 86, 87
Drilling, test, cost, 12

Dry processes, for cleaning stone, description, 363
Dunville stone (see Wisconsin)

Dale, T. Nelson, 103, 167, 181, 187, 189, 227, 239,

288
Daneker, Jerome G., 227

Eastern States, open pits in, characteristics, 18
Eckel, E. C, 102, 167, 227, 288, 387, 471
Ecuador, marble of, 331

498

THE STONE INDUSTRIES

Egypt, alabaster of, 343

granite of, 316

Great Pyramid, construction, 306

obelisks, construction, 316

onyx marble of, 332

red porphyry of, 346
Electric detonators, connecting wires, methods,
458
diagram, 458
Electrical slate, consumption, centers, 285

manufacture, description, 276
flow sheet, 277, 278
Emery, A. H., 385
Engineering and Mining Journal, 19
England, alabaster of, 343

Bath Abbey, construction, 308

Canterbury Cathedral, construction, 304

Cornwall, granite of, 313

Derbyshire, blue John of, 344
marbles of, 329

Devonshire, granite of, 313
limestone of, 309
marbles of, 328

Dorset, limestone of, 308

Eddystone Lighthouse, construction, 313

Ely Cathedral, construction, 309

Glastonbury Abbey, construction, 308

London Bridge, construction, 313

marbles of, 328

Northumberland, sandstone of, 310

Peterborough Cathedral, construction, 309

Rutland, oolitic limestone of, 309

St. Paul's Cathedral, construction, 308

sandstone of, 310

slate of, 336

Tintern Abbey, construction, 310

Warwick Castle, construction, 311

Warwickshire, ferruginous limestone of, 309

Wells Cathedral, construction, 308

Westminster Abbey, construction, 304

Wiltshire, limestone of, 307
quarrying methods, 307
Equipment, mechanical, for stripping, discussion,

16
Erosion cavities, stripping difficulties caused by,

14
Esopus stone (see New York, Ulster County)
Euclid bluestone (see Ohio)
Europe, slate industry, history, 236
Excavator (see Dragline scraper)
Expansion, effect on stone, 353
" Exploration and Geological Examination of a

Quarry Property," 19
Explosives, types used, 85

"Farm Layout, Economic Study of," 298
Federal Board for Vocational Education, 167, 368

acknowledgment, 113, 158
Federal Specifications Board, grading of roofing

slate by, 283
Fences, stone, cubic contents, 298

data, 297

mileage, 297

"Fencing Farms in North Central States, Cost

of," 298
Ferguson, E. G. W., 232
Fertilizer filler, crushed limestone in, 394
Figure stone (see Agalmatolite)
"Finding New Mines," 19
Finland, granite of, 315
exports, 315

manufactured, imports from, 166
red imports from, 166
Flagging, application, 26

"Flagstone Industry in Northeastern Pennsyl-
vania," 102
Flint, definition, 234

uses, 346
Floe rock, occurrence, 488
Floors, type of slate used for, 236
Florida, Alachua County, limestone quarries in,
403

Anastasia Island, coquina of, 38

Bradenton, travertine of, 44

Broward County, road stone of, 404

Citrus County, limestone of, uses of, 403

coquina of, 37, 403

coral limestone of, 403

crushed-limestone industry of, 403

Dade County, limestone of, uses, 404

Duval County, crushed-stone production, 404

Glades County, shell marl of, 404

Hernando County, limestone of, uses, 403

Jackson County, limestone of, uses, 403

Levy County, crushed-stone plants in, 403

limestone of, 403

Marion County, flint production of, 480
limestone of, uses, 403

Monroe County, coquina of, 38

Pinellas County, Tampa limestone of, 38

St. Augustine, coquina construction in, 38

Suwannee County, road stone of, 404

Tampa limestone of, 403

Volusia County, coquina of, 38
road stone of, 404
"Florida, Geology of," 470
"Florida, Limestones and Marls of," 471
Floridene stone, characteristics of, 44
Fluorite, uses, 344
Fluxing-stone quarries, methods at, description,

469
Fossil wood, uses, 346
Fossiliferous marble, deposits, 326
France, Ain, blue marble of, 324

alabaster of, 343

Calais, marble of, 324

granite of, 315

Hautes-Pyr6n6es, marble of, 323

Herault, marble of, 324

Isere, limestone of, 305

limestone industry in, canal transportation,
view, 305

marble of, 323

Meuse, limestone of, 304
view, 304

Normandy, limestone of, 304

onyx marble of, 332

Paris Basin, limestone of, 305

sandstone of, 310

INDEX

499

France, Savoie, marble of, 324

slate of, 337

Yonne, limestone of, 304
French Broad belt (see Tennessee)
"French Slate Quarries, Visit to," 341
Friendsville area (see Tennessee)
Frost action, effect on stone, 354
Fullerton, W. J., 471
Furnace flux, use of limestone as, 389

Gadder, definition, 210

view, 215
Galliher, E. Wayne, 102
Gang saws, description, 92
in marble mill, view, 218
Ganister, definition, 67, 473
industry by states, 477
production, 476
uses, 473
Ganser, J. W., 471
"Gems and Gem Materials," 347
Georgia, Atlanta district, royalty paid in, 32
Bartow County, lime industry, 404

slate of, 252
Catoosa County, road stone of, 404
Cherokee County, marble of, 195, 198
Crisp County, crushed-stone output, 405
crushed granite sold in, 475
crushed-limestone industry, 404
crushed-stone industry, 480
De Kalb County, building granite of, 131

granite of, uses, 480
Elbert County, granite of, 132
Gilmer County, waste marble, uses, 404
granite of, description, 131

forcing sheeting planes, with compressed air,

150
production data, 131
removal of stone from quarry, 154
Hancock County, granite of, 132
Henry County, granite of, uses, 480
Houston County, limestone of, uses, 405
limestone of, 404
marble, production data, 194
quarrying, channeling, 208
view, 208
Pickens County, marble of, 194, 196
arrangement, diagram, 195
waste marble, uses, 404
Polk County, cement plants, 404

roofing slate of, 251
Randolph County, travertine of, uses, 405
Stevens County, granite of, uses, 480
Stone Mountain, Confederate memorial, 131
Washington County, crushed-stone output, 405
"Georgia, Granites and Gneisses of," 167
"Georgia, Marbles of," 197, 227
"Georgia, Slate Deposits of," 289
"Georgia, Tate Quadrangle, Geology of," 194, 226
"Georgia Marble, Romance of," 227
Georgia Marble Company, acknowledgment, 208,

215
Germany, basalt paving manufacture, 316
granite of, 315

Germany, granite of, exports, 316

manufactured, imports from, 166

Hanover, onysette of, 332

marble of, 329

meerschaum-carving industry, 346

Saxony, agalmatolite of, 342

slate of, 339
" Gesteinsprilfung, Handbuch der bautechnis-

chen," 288
Glass, manufacture, use of limestone, 393
Glass seams, definition, 175
Gloryhole mining (see Mining, gloryhole)
Gneiss, classification, 7

deposits, 138
Gopher-hole blasting, description, 456
Gordon, Charles H., 181, 227
Goudge, M. F., 340, 471
Grain, definition, 108, 173, 233
Granite, bibliography, 167

black, deposits of 123, 130, 131, 132, 137, 140

block quarries, separating large masses in, 150

blocks, subdivision, 151
view, 152

carving, 160

channeling, 148
view, 149

chemical composition, 104

cleaning, approved methods, 365

color, 105

composition, 103

crushed, production, 371, 475

deposits, distribution, 112

dikes, 109

dimension, uses. 111
table showing, 112

drilling, procedure, 144
rate, 145

exports, 166

finishing, mechanical equipment, 160

foreign deposits, 311

hair lines. 111

hardness, 105

imports, 166

industry, discussion, 103

joints, 106
diagram, 107

knots, 110

marketing, 166

milling, methods, description, 156
hand cutting, 157
tools, 157
sketch, 158
surfacing machine, 159

mills, arrangement, 165
storage facilities, 165

physical properties, 104

porosity, 105

prices, 167

quarrying (see Granite quarrying)

related rocks, 106

rift and grain, 108

sand blasting, 160

sheet quarries, separating large masses, 150

sheeting planes, quarrying, 147
view, 148

structural features, 106

500

THE STONE INDUSTRIES

Granite, tariff, 167

texture, 105

varieties, 105

weathering effects, 359
"Granite," 167

"Granite, as Dimension Stone, Trends in Produc-
tion and Uses of," 114, 167
"Granite Cutting," 158, 167
Granite gneiss, deposits, 139

Granite quarrying, blasting, by Knox method,
145, 146

costs, 156

(See also "Quarry Costs, Study of")

haulage methods, 154

hoisting, 146

location, 143

methods, discussion, 143, 147

operations, 143
view, 144

plan, 143

removal of stone, 154

service yard, 154

waste disposal, 155

wedging, 146
Granules, production, 333, 473, 479, 483, 484, 490

use in roofing, 236
Greece, Athens, Parthenon, construction, 328

green porphyry of, 346

marbles of, 328

meerschaum of, 346

Mount Pentelicus, marble of, 328

Paros, marbles of, 328
Green marbles, deposits, 317, 328, 329

(See also Cipolin marbles)
Greenstone, deposit, 295
Greer, L., 341
Grimsley, G. P., 449
Grindstones, manufacture, 96

view, 96
Grit stone, rubbing with, disadvantages, 363
Guatemala, marble of, 331
Gypsum, massive, deposit, 342

Hair lines, definition. 111
Hammer drills, use, 84

in crushed-limestone quarries, 453, 454
Hand methods, for removing overburden, 16
Hansen, J. M., 228
Hard rolls, definition, 245
Hard way, definition, 108
Hardness, relationship to workability, 27
Hatmaker, Paul, 114, 167
Hauer, D. J., 19

Haulage, in slate quarries, methods used, 268
Hawaii, basalt sold in, 477
Hess, Frank L., 109
"Highway Material, Tentative Specifications

for," 379
Hirschwald, J., 288
Hoisting, granite, methods, 146

sandstone, equipment, 90
view, 90

slate, methods, 261
Holden, E. F., 347

Holland, The Hague, Peace Palace, construction,

314
Hopkins, T. C, 65

acknowledgment, 301
Horton stone (see England, Warwickshire)
Hotchkiss, W. O., 471
Hughes, H. Herbert, acknowledgment, 179, 238,

293, 295, 300, 470
Hummelstown brownstone (see Pennsylvania)
Humphrey, H. N., 298

Hydration, of minerals, effect on stone, 350
"Hydraulic Removal of Overburden from a

Stone Quarry," 19
"Hydraulic Stripping," 19
Hydraulic stripping, description, 14

■view, 15
"Hydraulic Stripping of Overburden," 19
"Hydraulic Stripping of Quarry Overburden," 19

Ice, use as building material, 346

Idaho, Ada County, sandstone of, 74

Bannock County, limestone of, uses, 405
basalt sold in, 477

Bonner County, limestone of, uses, 405
Boundary County, crushed-stone production,

481
Butte County, limestone of, use in sugar, 405
Cassia County, limestone of, uses, 405
Clearwater County, altered granite of, 481

limestone products, 405
crushed-limestone industry, 405
crushed-stone industry, 480
Kootenai County, limestone of, uses, 405
limestone of, 405
Nez Perce County, basalt of, use, 480

limestone of, uses, 405
Teton County, limestone of, use in sugar, 405
volcanic tuff of, 142

"Idaho, Tertiary Volcanic Tuffs and Sandstones
Used as Building Stones in," 142

Illinois, Adams County, limestone of, 38, 407
Alexander County, novaculite deposit, use as

road base, 481
Boone County, dolomites of, use, 406
Calhoun County, limestone of, uses, 407
Cook County, limestone of, uses, 406
crushed-limestone industry, 405

production data, 406
crushed sandstone sold in, 476
crushed-stone industry, 481
Du Page County, limestone of, uses, 406
Green County, limestone of, uses, 407
Hardin County, limestone of, uses, 408
Jersey County, limestone of, uses, 407
Johnson County, limestone of, uses, 408
Kankakee County, limestone of, uses, 406
Kendall County, limestone of, uses, 406
La Salle County, limestone of, uses, 406
Lee County, limestone of, uses, 406
limestone of, 38, 405
Madison County, limestone of, 38, 407
Monroe County, limestone of, uses, 407
Randolph County, limestone of, uses, 407
Rock Island County, limestone of, uses, 407

INDEX

501

Illinois, St. Clair County, limestone of, uses, 407
Union County, limestone of, uses, 408
Will County, limestone of, 38, 407
Winnebago County, limestone of, uses, 407
" Illinois, High-calcium Limestone near Morris,

471
"Illinois, Limestone Resources of," 471
"Illinois, Portland Cement Resources of," 470
Imports, of stone, 301
table showing, 302
India, Burma, jadeite of, 345
slate of, 340

Taj Mahal, construction, 331
Indian pipestone (see Catlinite)
Indiana, " Bloomington Quadrangle, Geology of,"
65
Cass County, limestone of, uses, 409
Clark County, limestone of, uses, 408
Crawford County, limestone of, uses, 408
crushed-limestone industry, 408

production data, 408
Daviess County, limestone of, uses, 408
Decatur County, limestone of, 39, 408
Delaware County, limestone of, uses, 409
dimension limestone, production data, 38
Floyd County, abrasive sandstone of, 74
Harrison County, lime production, 408
Howard County, limestone of, uses, 409
Jasper County, limestone of, uses, 409
Jay County, limestone of, uses, 409
Jefferson County, limestone of, uses, 408
Jennings County, limestone of, uses, 408
La Grange County, cement plant, 409
Lake County, cement plant, source of materials,

409
Lawrence County, limestone of, 39

uses, 409
limestone of, 38, 408
beds, channeling, 46
\dew, 46
stripping methods, 45
turning down blocks in, view, 50
wire saw, use, 48
color, 40
description, 38
durability, 40
grades of stone, 41
hardness, 40
production data, 38
reserves, 41
Madison County, limestone of, uses, 409
"Method and Cost of Quarrying Limestone

at Speed Quarry," 470
Mom'oe County, limestone of, 39, 409
Newton County, limestone of, uses, 409
oolite (see Indiana, limestone of)
Orange County, sandstone of, 74

whetstone manufacture, 74
Owen County, limestone of, 39

uses, 409
prospecting, 41

Putnam County, limestone of, uses, 409
Ripley County, limestone of, uses, 408
Rush County, road-stone quarries, 409
Salem limestone of, 39
sandstone of, 74

Indiana, Spencer County, building sandstone of,
74
"travertine" of, 41

Wabash County, limestone of, uses, 409
Washington County, limestone of, uses, 408
Wells County, road-stone quarries, 409
White County, limestone of, uses, 409
"Indiana, Bedford Oolitic Limestone of," 65
"Indiana, Southern, Geologic and Topographic

Section Across," 66
"Indiana, Southern, Geology of Lower Car-
boniferous of," 65
" Indiana Limestone, Efflorescence and Staining,"

65
" Indiana Limestone District, Hydraulic Stripping

in the," 19
"Indiana Limestone District, Quarry Waste in,"

63
"Indiana Oolitic Limestone," 40, 41, 65
Ingels, C. W., 379
Ingersoll-Rand Company, acknowledgment, 247,

264
Ink stains, removal from stone, 367
Iowa, Allamakee County, crushed-limestone
industry, 410
Black Hawk County, crushed-limestone indus-
try, 410
Bremer County, crushed-limestone industry,

410
Cerro Gordo County, cement plants, 410
Clayton County, crushed-limestone industry,

410
crushed-limestone industry, 409

production data, 409
Dubuque County, crushed-limestone industry,

410
Fayette County, crushed-limestone industry,

410
Floyd County, crushed-liniestone industry, 410
gypsum of, 342

Hardin County, limestone quarries, 410
Jackson County, lime plant, 410
Johnson County, crushed-limestone industry,

410
Jones County, crushed-limestone industry, 410
Lee County, limestone quarries, 410
limestone of, 409

Linn County, crushed-limestone industry, 410
Madison County, limestone quarries, 410
Marshall County, limestone quarries, 410
Mitchell County, limestone of, use for sugar

manufacture, 410
Pocahontas County, cement plant, 410
Polk County, cement plants, 410
Scott County, cement plant, 410
Van Buren County, limestone quarries, 410
Winneshiek County, road-stone quarry, 410
Ireland, granite of, 313
marbles of, 329
slate of, 336
Iron ores, need of furnace flux in smelting, 389
Iron stains, removal, 367
Iron sulphides, as impurities in marble, 175
Isle La Motte district (see Vermont)

502

THE STONE INDUSTRIES

Italy, alabaster of, 343

Carrara district, as center of marble industry,
168
history, 319

marbles of, description, 318
milling methods, 321
quarrying methods, 319

view, 321
view, 320
granite of, 316
exports, 316
Istria, marbles of, 322
limestone of, 306

quarrying methods, 306
marbles of, 318

Naples, calcareous tufa of, 307
Rome, buildings, marble for, source, 319, 330
Colosseum, construction, 307
St. Peter's Church, construction, 307, 323
Siena, marbles of, 321

haulage, view, 322
slate of, 339

exports, 339
travertine of, 307
"Italy, Mining Marble with Helicoidal Wire in,"
341

Jade, uses, 344

(See also Jadeite; Nephrite)
Jadeite, uses, 344, 345

Japan, pumice of, use as building material, 344
Jennsen tower system, description, 393
Jenny Lind {see Buffer)
Joints, definition, 233

origin, 174
Joplin district (see Missouri)

Kansas, Allen County, limestone of, uses, 411
Anderson County, crushed-limestone industry,

411
Atchison County, crushed-limestone industry,

411
Bourbon County, limestone of, uses, 411
Butler County, crushed-limestone industry, 411
Cherokee County, crushed-limestone industry,

411
Cowley County, limestone of, 41
crushed-limestone industry, 410
production data, 411
crushed sandstone sold in, 476
crushed-stone industry, 481
Douglas County, crushed-limestone industry,

411
Elk County, crushed-limestone industry, 411
Franklin County, crushed-limestone industry,

411
Geary County, crushed-limestone industry, 411
Johnson County, crushed-limestone industry,

411
Labette County, crushed-limestone industry,

411
limestone of, 41, 410

Kansas, Lincoln County, quartzite, use as
concrete aggregate, 481
Linn County, asphaltic sandstone of, 481
Montgomery County, cement industry, 411
Neosho County, cement industry, 411
Riley County, limestone of, 41
Shawnee County, crushed-limestone industry,

411
Wilson County, cement industry, 411
Wyandotte County, limestone of, uses, 411
Kentucky, Anderson County, crushed-limestone
industry, 412
bituminous rock sold in, data, 482
Boyle County, crushed-limestone production,

412
Breckenridge County, bituminous sandstone of,

481
Bullitt County, limestone of, 412
Campbell County, riprap production, 412
Carter County, crushed-limestone industry, 412
crushed-limestone industry, 411

production data, 411
crushed sandstone sold in, 476
crushed-stone industry, 481

production data, 481
Edmonson County, bituminous sandstone of,

481
Franklin County, crushed-limestone industry,

412
Grayson County, bituminous sandstone of, 481
Hardin County, bituminous sandstone of, 481
Jefferson County, limestone of, uses, 412
Jessamine County, crushed-limestone industry,

412
Lee County, crushed-limestone production, 412
limestone deposits, 42, 411
Livingston County, riprap production, 412
Meade County, limestone of, 412
Pulaski County, crushed-limestone production,

412
Rockcastle County, crushed-limestone produc-
tion, 412
sandstone of, 74
Rowan County, building sandstone of, 74
sandstone of, 74
Taylor County, lime plant, 412
Warren County, limestone of, 42
"Kentucky, Building Stones of," 66
Kessler, D. W., 29, 65, 227, 288, 361, 366, 368
Kirk, Raymond E., 471
Knots, definition, 110

Knox system, of blasting, description, 85
Knoxville belt (see Tennessee)
Kraus, E. H., 347
Krey, Frank, 471
Kriege, Herbert, F., 385
Kummel, H. B., 471

Labor problems, as factor in production costs, 10

Labradorite, deposits of, 345

Ladoo, R. B., 347

Lake Superior brownstone (see Wisconsin)

Lamar, J. E., 383, 471

Landes, Henry, 492

INDEX

503

Laney, F. B., 167
Lapis-lazuli, deposits of, 345

uses, 345
Lardstone {see Agalmatolite)
Laurvikite, occurrence, 314, 345

uses, 345
Lawton, E. M., 340
Layman, F. E., 470

Lehigh district (see New Jersey, Sussex County;
Pennsylvania, Lehigh County and North-
ampton County)
Lent, Frank A., 227, 340
Lewis, J. Volney, 471

Lime, high-magnesian, use of dolomite for, 394
industry by states, 396
manufacture, 387
plants, quarries, methods, description, 469

view, 389
production, 388
quarrying methods, 452
"Lime Industry, Quarry Problems in," 470
"Lime — Its Use and Value in Industrial and

Chemical Processes," 471
"Lime and Portland Cements for Masonry Mor-
tars," 358
Limestone, aggregate, discussion, 378
argillaceous, in mineral wool, 394
beds, channeling, description, 46
view, 46

cutting, with wire saw, 48
hoisting blocks in, description, 52

view, 52
key block, removal, description, 48
diagram, 49
view, 48
lifting, description, 50

diagram, 49
stripping, methods, 45
Bubdiv-iding blocks in, description, 51

view, 52
turning down blocks in, description, 51
views, 50, 51
bibliography, 65
cleaning, approved methods, 365
crushed, in alkali, 391
as asphalt filler, 385
bibliography, 470
in calcium carbide, 392
chemical properties, importance, 385
as concrete-block aggregate, 384
as concrete-block facing, 384
for dusting coal mines, 381
extent of industry, 377
as fertilizer filler, 394
as furnace flux, 389
in glass manufacture, 393
industry by states, 396
as limestone sand, 384
in paper manufacture, 393
as poultry grit, 384
production, 371
as railroad ballast, 380
in refining sugar, 392
as riprap, 380
as road stone, 380
as roofing gravel, 385

Limestone, crushed, in rubber manufacture, 393
in sewage filter beds, 383
in stock food, 394
stone included, 377
for surfacing, 384
as terrazzo, 384
uses, 377
definition, 33

dimension, production, by uses, table, 36
districts. Middle West, position of beds, 17
finishing mill, view, 61
foreign, discussion, 302
industry by states, 37, 396
manufacture, waste, 63
marbles, origin, 169
marketing, 65
milling, costs, 63
cutting, 59
drafting, 55

finished surfaces, types, 60
handling blocks, 55
methods, discussion, 55
planing, 58
sawing, 56
ticket system, 55
turning, 59
origin, 33

physical properties, 33
preparation for shipping, 61
products, preparation, 62
qualities, 35

quarrying, cleaning floor, 53
costs, 63

methods, 45, 306, 307
scabbling methods, 53
transportation of blocks, 53
waste, 63
sand, preparation, 384
uses, 36
varieties, 33
waste, utilization, 64
weathering effects, 359
"Limestone in Industry," 471

"Limestone Mining, Underground," 467, 468, 472
"Limestone, Quicklime, and Hydrated Lime for

Use in Manufacture of Sugar," 392
"Limestone Sand, Washed," 385
"Limestone for Sewage Filter Beds," 383
Lines, E. F., 470
Linseed-oil stains, removal, 368
Liquid oxygen explosive, use in blasting, 455
Litoslazuli, description, 344
Logan, W. N., 471
Loughlin, G. F., 40, 41, 65, 368, 471
Louisiana, crushed-limestone industry, 412
Evangeline Parish, limestone of, 413
Winn Parish, limestone of, 412
Lowe, E. N., 471
Luttrell belt (see Tennessee)
Luxemburg, slate of, 338

McAnally, S. G., 471
McCalley, Henry, 472
McCallie, S. W., 197, 227

504

THE STONE INDUSTRIES

Madagascar, amazonite deposits, 343
Maine, Androscoggin County, crushed-stone
production, 481
Aroostook County, limestone of, 413
crushed granite sold in, 475
crushed-limestone industry, 413
crushed-stone industry, 481

Cumberland County, crushed-stone production,
481
monumental granite of, 128
Franklin County, building granite of, 128
granite of, 127

hoisting equipment, 147
production, 127
sheet structure, view, 148
Hancock County, granite of, 128

sheeting planes, 108
Kennebec County, building granite of, 129
Knox County, limestone of, 413

pa^^ng-stone granite of, 130
lime production, 388
limestone of, 413
Lincoln County, granite of, 130
Monson district, slate of, 239
quarrying methods, 266
diagram, 266
North Blanchard district, slate of, 241
Piscataquis County, slate of, 241
slate of, description, 239
hoisting methods, 261
manufacture of mill stock, 276
production data, 239
structure, 253
Somerset County, crushed-stone production,
481
granite of, 130
Waldo County, monumental granite of. 130
Washington County, monumental granite of,

130
York County, monumental granite of, 131
Malachite, deposits of, 345

uses, 345
"Manitoba, Nonmetallic Mineral Resources of,"

341
Manitou Green-Stone (see Colorado)
"Marble," 227
Marble, bibliography, 226
color, cause, 171

(See also Black marble; Cipolin marble;
Green marble; Statuary marble)
composition, 168
definition, 168
deposits, distribution, 178
exports, 226
foreign, 316

geology, need for knowing, 177
hardness, 170
history, 168

imports, table, 225, 317
impurities, 175
industry, discussion, 168

by states, 181
interior, maintenance, 366

stains on, treatment, 367
jointing, 174
map, 179

Marble, marketing, 224

milling, finishing processes, description, 219
views, 220, 221
methods, 216
sawing, 218
View, 218
sources of power, 216
use of gang saw, 218
view, 218
mills for finishing, arrangement, 217

diagram, 217
origin, 169

pattern work, cutting, 222
physical properties, 170
porosity, 173
prices, 226

production data, tables, 180
prospecting for, 206

quarrying, channeling, description, 208
views, 208, 215
drilling, 210
hoisting, equipment, 214

view, 215
key blocks, handling, 212
methods, 206
plan, 207
scabbling, 216
transportation, 216
undercutting, 214

view, 215
underground, description, 213

diagram, 213
waste, prevention, 223

utilization, 224
wedging, 211

diagram, 212
wire saws, use, 210
rift, 173

silicated, uses, 177
solubility, 171
specific gravity, 171
strength, 173
tariff, 226
texture, 172

trade names (.See states and countries named)
translucence, 172
unsoundness, 175
uses, 178
varieties, 169

verde antique (See Verde antique)
weathering effects, 359
"Marble Decoration," 323

Marble Hill district {see Georgia, Pickens County)
" Marble, Interior, Problems Relating to Main-
tenance of," 227, 368
"Marble and Marble Working," 228, 325, 341
"Marble Quarrying, Technology of," 226
Marcasite, as impurity in marble, 175
Marine borers, effects on stonework, 357
Marketing, bluestone, 101
building limestone, 65
crushed stone, 492
granite, 166
marble, 224
problems, solving, 31
slate, 284

INDEX

505

Marketing soapstone, 294

"Marketing of Metals and Minerals," 288

Markets, for stone products, importance of study,

8
Marsh, J. E., 368
Marsh, Robert, Jr., 471

Maryland, Allegany County, ganister of, 483
limestone of, 414
road-stone production, 414
Baltimore County, basalt quarries, 481
dolomite of, 42
gneiss of, 138
granite of, 138, 483
limestone of, 42, 413

uses, 414
marble of, 205
serpentine of, 205
basalt sold in, 477
Carroll County, lime industry, 414

limestone of, 413
Cecil County, crushed-stone production, 481

granite of, 138
crushed granite sold in, 475
crushed-limestone industry, 414
crushed sandstone sold in, 476
crushed-stone industry, 481
dolomite of, 42

Frederick County, conglomerate of, 205
limestone of, 414
uses, 414
Garrett County, limestone of, 414

road-stone production, 414
gneiss of, description, 138
granite of, description, 137

production data, 137
Harford County, crushed-stone industry, 481
serpentine of, 205
slate of, 249

quarrying methods, 266
terrazzo production, 414
verde antique of, 205
Howard County, limestone of, 413
limestone of, 42, 413
marbles of, 205

Marriottsville, soapstone of, 291
Montgomery County, gneiss of, 138

granite of, 483
Peach Bottom district, slate of, structure, 253
Washington County, limestone of, uses, 414
"Maryland, Building and Decorative Stones of,"

167, 227
" Maryland Building Stones, Character and

Distribution of," 288
"Masonry Cements, Analysis of Properties

Desired in," 358
" Masonry Decay from Weathering, Economic

Aspects of," 368
Massachusetts, basalt sold in, 477

Berkshire County, limestone of, uses, 414
marbles of, 202
monumental granite of, 117
Boston, First Church of Christ Scientist, con-
struction, 135
Bristol County, building granite of, 117

crushed-granite production, 483
crushed granite sold in, 475

Massachusetts, crushed-limestone industry, 414
production data, 414
crushed sandstone sold in, 476
crushed-stone industry, 483
Essex County, crushed-stone industry, 483

granite of, 117
Franklin County, crushed-basalt production

483
granite of, description, 116
drilling method, 149
production data, 116
Hampden County, building granite of, 118
crushed-basalt industry, 483
sandstone of, 74
verde antique of, 202
Hampshire County, building granite of, 118

crushed-basalt industry, 483
marbles of, description, 202

production data, 202
meerschaum of, 346
Middlesex County, crushed-stone industry, 483

granite of, 118
Norfolk County, crushed-granite production,
483
granite of, sheeting planes, 108
monumental granite of, 119
Plymouth County, building granite of, 120

crushed-granite production, 483
Suffolk County, crushed-stone industry, 483

road-stone production, 483
Worcester County, building granite of, 120
flint production, 483
Massey, G. B., 19
Materials, accessory, faults, effects on stonework,

357
Matthews, E. B., 167, 227, 288
Meadow belt (see Tennessee)
Meerschaum, deposits of, 345

uses, 346
Memorials, stone for, types required, 25
Merrill, G. P., 12, 29, 103, 167, 227, 340, 344,

347, 349, 368
Merritt, C. A., 433
" Metallurgical Limestone," 470
Metals, competition from, 9
Mexican onyx, composition, 35
" Mexican Onyx, Genesis and Classification of,"

340
Mexico, Lower California, onyx marbles of, 331
Mica schist, deposits of, 346, 484, 488

uses, 346
Michigan, Arenac County, limestone outcrops,
416
Baraga County, roofing slate of, 252
basalt sold in, 477
Branch County, cement mills, 416
cement industry, 416

Cheboygan County, limestone of, uses, 418
crushed-limestone industry, 415
crushed sandstone sold in, 476
crushed-stone industry, 483
Delta County, limestone of, uses, 418
Dickinson County, limestone of, uses, 418
Eaton County, limestone of, uses, 416, 417
Emmet County, cement plant, 417
Fillmore County, limestone of, uses, 420

506

THE STONE INDUSTRIES

Michigan, Genesee County, cement mills, 416
Gogebic County, crushed-basalt production,

483
Houghton County, crushed-basalt production,

483
Huron County, abrasive sandstone of, 74

limestone of, 416, 418
Iron County, crushed-basalt production, 483
Lenawee County, cement plant, 416
lime industry, 417
limestone of, 415, 472

production data, 416
Mackinac County, limestone of, uses, 418
Marquette County, crushed-basalt production,
483
sandstone of, use in highway construction,

483
verde antiques of, 205
Menominee County, raw-limestone industry,

417
Monroe County, dolomite of, 415

limestone of, uses, 418
Newaygo County, cement mill, 417
Presque Isle County, limestone of, 415, 417
raw-limestone industry, 417
Schoolcraft County, limestone of, uses, 417, 418
Washtenaw County, cement plant, 416
Wayne County, limestone of, uses, 417, 418
Winona County, limestone of, uses, 420
Microcline (see Amazonite)
Milkowski, V. J., 19

Mill method, of manufacturing roofing slate,
description, 270
diagram, 272
Mill stock, manufacture, drilling holes, 276
methods, 274
sawing, 274
storage, 277

surface finishing, 275
use of slate as, 235
Mille, definition, 235
Miller, B. L., 435, 471
Milling methods, building limestone, 55
granite, 156
marble, 216
sandstone, 92
slate, 274
soapstone, 293
" Mineral Fillers for Sheet-asphalt Paving Mix-
tures," 385
" Mineral Industry," 288
" Mineral Products, Fundamental Factors in

Testing," 288
" Mineral Resources of the United States," 167,

227, 288, 470, 492
Mineral wool, use of argillaceous limestone, 394,

409, 442
Minerals, composing rocks, determination, 26

list, 5
" Minerals Yearbook," 288
Mining, gloryhole, use, 18

underground, advantages, 18, 467
application, 18
instead of stripping, 17
Minnesota, basalt sold in, 477
Benton County, granite of, 123

Minnesota, Big Stone County, monumental

granite of, 124
Blue Earth County, dolomitic limestone of, 42

limestone of, 419
catlinite of, 75

Crow Wing County, marl of, 420
crushed granite sold in, 475
crushed-limestone industry, 418
crushed sandstone sold in, 476
crushed-stone industry, 484
Dodge County, dolomitic limestone of, 42
dolomitic limestone of, description, 42
Goodhue County, crushed limestone of, 420
granite of, 121

hoisting equipment, 147

production data, 121
Hennepin County, limestone of, uses, 419
Houston County, riprap production, 420
Lake County, granite of, use in highway con-
struction, 484
Le Sueur County, dolomitic limstone of, 42

marble of, uses, 419
limestone of, 418

production data, 419
Mille Lacs County, monumental granite of, 123
Minnesota River Valley, granite of, 124
Morrison County, monumental granite of, 123
Mower County, limestone plant, 419
Nicollet County, quartzite of, use, 484

sandstone of, 75
Olmsted County, limestone of, uses, 419
Pine County, crushed-sandstone industry, 484

sandstone of, 74
pipestone of, 75
Pipestone County, catlinite of, 344

quartzite of, uses, 484

sandstone of, 75
Ramsay County, limestone of, uses, 419
red granite of, composition, 103
Redwood County, granite of, 124
Renville County, granite of, 124
Rice County, limestone of, uses, 420
Rock County, abrasive sandstone of, 75

quartzite of, use as concrete aggregate, 484
St. Cloud district, granite of, 121
block quarries, 147

sheeting planes, 108

strike of joints, diagram, 107
St. Louis County, basalt of, uses, 484

cement plants, 419
sandstone of, description, 74
Sherburne County, building granite of, 123
Stearns County, monumental granite of, 122
Winona County, dolomitic limestone of, 42

travertine of, 44
" Minnesota, Structural and Ornamental Stones

of," 167
Miscellaneous stone (see Crushed stone)
" Mississippi, Cement and Portland Cement

Materials of," 470
Mississippi, Chickasaw County, chalk of, 420
crushed-limestone industry, 420
crushed sandstone sold in, 476
limestone of, 420
Rankin County, limestone of, 420
Warren County, limestone of, 420

INDEX

507

Mississippi, Wayne County, limestone of, 420
"Mississippi, Road-making Materials of," 471
"Mississippi, Structural Materials of," 471
Missouri, Andrew County, limestone of, uses, 423

Buchanan County, limestone of, uses, 423

Callaway County, riprap production, 422

Cape Girardeau County, limestone of, uses, 422

Carroll County, sandstone riprap of, 484

Carthage district, marbles of, 198

cement industry, 421

Clay County, limestone of, uses, 423

crushed granite sold in, 475

crushed-limestone industry, 420

crushed sandstone sold in, 476

crushed-stone industry, 484

Franklin County, riprap production, 422

Greene County, flint of, use as concrete aggre-
gate, 484
limestone of, 421, 422

Iron County, crushed-granite production, 484
granite of, 142
rhyolite of, use as road stone, 484

Jackson County, limestone of, uses, 421, 422

Jasper County, limestone of, uses, 42, 198, 422

Jefferson County, lime plants, 421

Joplin district, marbles of, 199

Lawrence County, lime plants, 421

lime industry, 421

limestone of, 420

production data, 421

Lincoln County, limestone of, uses, 422

marbles of, 42
description, 198

Marion County, limestone of, uses, 421, 422

Ozora district, marbles of, 199

Phenix district, marbles of, 199

St. Charles County, limestone of, uses, 422

St. Clair County, lime plants, 421

Ste. Genevieve County, limestone of, uses, 421,
422

St. Louis County, limestone of, uses, 421, 422

South Greenfield district, marble of, 199

Wayne County, crushed-granite production,
484
"Missouri, Quarrying Industry of," 167, 198, 470
Monson district (see Maine)
Montana, basalt sold in, 477

Broadwater County, black marble of, 205

Cascade County, quartzite of, use for brick, 484
limestone of, uses, 423

crushed granite sold in, 475

crushed-limestone industry, 423

crushed sandstone sold in, 476

crushed-stone industry, 484

Deerlodge County, limestone of, uses, 423

Fergus County, cement plant, 423

Flathead County, basaltic rock of, use for
riprap, 484

Gallatin County, limestone of, uses, 423
onyx marble of, 205

Gardiner, travertine of, 44

Granite County, limestone of, use for sugar
manufacture, 423

Jefferson County, limestone of, uses, 423

Lewis and Clark County, granite of, use for
riprap, 484

Montana, limestone of, 423

Lincoln County, basaltic rock of, use for

riprap, 484
Madison County, onyx marble of, 206
monumental granite of, 142
Musselshell County, riprap quarry, 423
Park County, calcite of, uses, 423
Phillips County, travertine of, 44
Powell County, lime production, 423
quartzite of. Bureau of Standards tests, 28
Silver Bow County, altered granite of, use for
riprap, 484
Monumental stone, definition, 25

(See also Granite; Marble)
Moore, E. S., 492
Morocco, meerschaum of, 346
Morrison, George A., 471

"Mortar for Durable Unit Masonry, Funda-
mental Properties of," 358
Mossom, Stuart, 470, 471
Mud-capping method of blistering, description,

459
Multiple-bench quarrying, advantages, 456
Multiple series connection, for electric detonators,

description, 459
Myers, W. I., 298,
Myers, W. M., 470

Nash, J. P., 167

National Building Granite Quarries Association,

acknowledgment, 113
National Lime Association, 471
National Slate Association, 284, 288
Nebraska, Cass County, limestone of, uses, 424

crushed-limestone industry, 423

Gage County, limestone of, uses, 424

limestone of, 423

Nuckolls County, chalk of, use in cement, 424

Sarpy County, limestone of, uses, 424
Nephrite, deposits of, 345

uses, 344
Neubert Springs area (see Tennessee)
Nevada, Clark County, limestone of, uses, 424

crushed-limestone industry, 424

limestone of, 424

volcanic tuff of, 142, 143
"Nevada, White Pine County, Marble of," 227
"New England, Commercial Granites of," 103,

167
New Hampshire, Carroll County, building granite
of, 134
crushed-stone production, 484

Cheshire County, granite of, 135

Coos County, crushed-stone production, 484

crushed granite sold in, 475

crushed-limestone industry, 424

crushed-stone industry, 484

Grafton County, limestone of, use for lime, 424
mica schists of, uses, 346, 484

granite of, description, 134
production data, 134

Hillsborough County, granite of, 135
use as riprap, 484

limestone of, 424

508

THE STONE INDUSTRIES

New Hampshire, Merrimack County, granite of,
135
use as riprap, 484
Stafford County, granite of, use as road stone,
484
New Jersey, basalt sold in, 477

Bergen County, trap-rock quarries, 485
crushed granite sold in, 475
crushed-limestone industry, 424
crushed sandstone sold in, 476
crushed-stone industry, 484
Essex County, crushed-stone plants, 485
Hudson County, crushed-stone plants, 485
Hunterdon County, argillite of, 75
limestone of, uses, 425
sandstone of, use as riprap, 485
trap-rock quarries, 484
limestone of, 424
Mercer County, argillite of, 75, 485

trap-rock quarries, 484
Morris County, granite of, 485
Passaic County, trap-rock quarries, 485
sandstone of, uses, 75
Somerset County, limestone of, uses, 425

trap-rock quarries, 485
Sussex County, limestone of, uses, 424, 425

slate of, 243, 244, 248
Union County, crushed-stone plants, 485
Warren County, limestone of, uses, 424, 425
verde antique of, 206
" New Jersey, Geology of," 471
Newland, D. H., 167, 227, 426, 471, 492
New Mexico, crushed-limestone industry 425
crushed sandstone sold in, 476
crushed-stone industry, 485
Grant County, meerschaum of, 346
Gaudalupe County, asphaltic sandstone of,

use for highway construction, 485
limestone of, 425
Mora County, caliche of, use for highway

construction, 485
San Juan County, lime plant, 425
San Miguel County, limestone of, uses, 425
Socorro County, crushed sandstone of, use as

railroad ballast, 485
volcanic tuff of, 142
Newsom, J. B., 48, 63, 66

acknowledgment, 305, 320, 321, 322
New York, Albany County, crushed-stone indus-
try, 485
limestone quarries, 427
sandstone of, 75

State Capitol, construction of, 311
basalt sold in, 477
bluestone production, 99
Broome County, sandstone of, 75
Cayuga County, limestone quarries, 428
Clinton County, granite of, 136
limestone of, uses, 427
marbles of, 201
Columbia County, cement plants, 427
crushed granite sold in, 475
crushed-limestone industry, 425

production data, 426
crushed sandstone sold in, 476
crushed-stone industry, 485

New York, Delaware County, sandstone of, 75
Dutchess County, limestone of, uses, 427, 428

marbles of, 201
Erie County, limestone of, uses, 427, 428
Essex County, crushed-granite production, 485
Fulton County, limestone of, uses, 427
Genesee County, limestone of, uses, 427, 428
gneiss of (see " New York, Quarry Materials

of")
granite of, description, 136

production data, 136

(See also " New York, Quarry Materials of")
Greene County, cement plants, 427

sandstone of, 75, 485
Hamilton County, crushed-granite industry,

485
Herkimer County, crushed-granite production,
485

lime plants, 427
Jefferson County, crushed-granite production,
485

granite of, 136

limestone of, \ises, 427, 428
limestone of, 42, 425

Madison County, limestone of, uses, 426, 428
marbles of, description, 201

production data, 201

(See also "New York, Quarry Materials of")
Monroe County, limestone of, uses, 426, 428
Montgomery County, limestone of, uses, 427
Niagara County, limestone quarries, 428

Medina sandstone of, uses, 486
Oneida County, limestone of, uses, 426, 428
Onondaga County, limestone of, 42, 426, 428
Ontario County, limestone of, uses, 428
Orange County, granite of, 136, 485

limestone quarries, 428

West Point Military Academy, construction,
136
Orleans County, Medina sandstone of, 75, 486
Oswego County, sandstone of, 486
Potsdam sandstone, of northern Adirondacks,

75
Rockland County, basalt of, uses, 485

limestone quarries, 428
St. Lawrence County, limestone of, uses, 428

marbles of, 201
sandstone of, 75

Saratoga County, limestone of, uses, 427
Schenectady County, sandstone of, use as

road stone, 485
Schoharie County, limestone of, uses, 427
slate of, description, 241

hoisting methods, 261

production data, 241

quarrying, floor breaks, 260

structure, 253
Steuben County, sandstone of, 486
Sullivan County, bluestone of, use as riprap,
485

sandstone of, 75
Tompkins County, cement plants, 427
trap rock of (see "New York, Quarry Materials

of")
Ulster County, bluestone of, composition, 97

esopus stone of, 71

INDEX

509

New York, Ulster County, limestone of, uses, 427
428
sandstone of, 75
Warren County, limestone of, uses, 427
Washington County, limestone of, uses, 427
slate of, 242, 243

quarry methods, 265
Westchester County, granite of, 136, 485
limestone quarries, 428
meerschaum of, 346
Wyoming County, sandstone of, 75
" New York, Method and Cost of Quarrying
Limestone at Plant of North American
Cement Corporation, Catskill," 471
" New York, Mineral Resources of the State of,"

426, 471
" New York, Quarry Materials of," 167, 227, 492
"New York, Tully Limestone of Central," 472
New York City, Cathedral of St. John the

Divine, construction, 136
Cleopatra's Needle, weathering, in Central

Park, 30
Grand Central Station, use of travertine, 34
Pennsylvania Railroad Station, construction,
120, 307
" Nonmetallio Minerals," 347
Nordmarkite, deposit of, 314
North, F. J., 288, 333, 340
North Blanchard district (see Maine)
North Carolina, Alexander County, granite of,
as source of crushed stone, 486
Buncombe County, granite of, as source of

crushed stone, 486
Cherokee County, crushed marble of, 429

marbles of, 206
crushed granite sold in, 475
crushed-limestone industry, 428
crushed-stone industry, 486
Davidson County, Piedmont Plateau granite

of, 127
Durham County, miscellaneous stone of, 486
Forsyth County, granite of, use for crushed

stone, 486
granite of, 124

forcing sheeting planes, with compressed air,

150
haulage methods, 155
production data, 124 .

removal from quarry, 154
Guilford County, as source of crushed granite,

486
Henderson County, Appalachian Mountain
granite of, 127
limestone of, uses, 428
limestone of, 428

McDowell County, limestone of, uses, 428
Madison County, limestone of, uses, 428
Mecklenburg County, granite of, as source of

crushed stone, 486
New Hanover County, limestone quarries, 429
Orange County, as source of crushed granite,

486
pyrophyllite of, 342
Rockingham County, as soiirce of crushed

granite, 486
Rowan County, as source of crushed granite, 486

North Carolina, Rowan County, Piedmont
Plateau granite of, 126
soapstone of, 291

Surry County, building-stone industry, use of
waste, 486
Piedmont Plateau granite of, 126
Vance County, as source of crushed granite, 486
Wake County, as source of crushed granite, 486

Piedmont Plateau granite of, 127
Wilson County, as source of crushed granite,
486
Coastal Plain granite of, 125
" North Carolina, Building and Ornamental

Stones of," 167
"North Carolina, Limestones and Marls of," 471
North Dakota, Cavalier County, cement plant,
429
crushed-limestone industry, 429
limestone of, 429
Norway, granite of, 313
marbles of, 330
slate of, 339
syenite of, 314

Trondhjem, cathedral at, construction, 290
Novaculite, characteristics, 73
deposits, 73, 481

Ohio, Adams County, limestone of, uses, 430, 432
Allen County, limestone of, quarries working,

432
Ashland County, miscellaneous rock of, as

source of crushed stone, 486
Athens County, sandstone of, use as aggregate,

486
Briar Hill stone of, 78

Carroll County, building sandstone of, 78
Clark County, quarries, 432
Clermont County, boulders of, uses, 486
Clinton County, quarries, 432
Columbiana County, building sandstone of, 78
Crawford County, limestone industry, 432
crushed-limestone industry, 431

production data, 430
crushed sandstone sold in, 475
crushed-stone industry, 486
Cuyahoga County, sandstone of, 77, 486
Delaware County, limestone of, uses, 430, 432
Erie County, limestone of, uses, 429, 431, 432
Euclid bluestone of, 77
Fairfield County, sandstone of, 78
Fayette County, quarries, 432
Franklin County, limestone of, uses, 430, 432
Greene County, limestone of, uses, 430, 431
Hancock County, limestone of, uses, 431
Hardin County, limestone of, uses, 430, 432
Harrison County, limestone of, uses, 432
Henry County, limestone of, uses, 429
Holmes County, building sandstone of, 78
Huron County, sandstone of, 76
Jefferson County, abrasive sandstones of, 78
Lake County, limestone of, uses, 431
Lawrence County, limestone of, uses, 430, 431
lime industry, 430, 431

510

THE STONE INDUSTRIES

Ohio, lime-manufacturing district, 389
view, 389
limestone of, 429

Logan County, crushed-stone production, 432
Lorain County, sandstone of, 76, 78, 486

view, 76
Lucas County, limestone of, uses, 429, 431
Mahoning County, limestone of, uses, 429

sandstone of, 78
Marion County, limestone of, uses, 432
Mercer County, limestone of, uses, 432
Miami County, limestone of, uses, 432
Montgomery County, quarries, 432
Muskingum County, limestone of, uses, 431,

432
Ottawa County, limestone of, uses, 430, 431,

432
Paulding County, limestone of, uses, 429, 431
Pickaway County, limestone of, uses, 429
Preble County, quarries, 432
Putnam County, limestone of, uses, 431
sandstone of, description, 76
quarrying, view, 90
use, as grindstones, 71
Sandusky County, limestone of, uses, 430, 431,

432
Scioto County, sandstone of, 76, 78, 486
Seneca County, limestone of, uses, 430, 432
Stark County, limestone of, uses, 429, 430, 431
Tuscarawas County, limestone of, uses, 430

sandstone of, use as aggregate, 486
Union County, crushed-stone production, 432
Van Wert County, limestone of, uses, 432
Washington County, abrasive sandstones of, 78
Wood County, limestone of, uses, 429, 430, 431
Wyandot County, limestone of, uses, 430, 432
"Ohio, Building Stones of," 81, 102
"Ohio, Limestone Resources and Lime Industry

in," 471
"Ohio, Mineral Industries of," 470
Oil stains, removal, 367

Oklahoma, Adair County, limestone for glass
manufacture, production, 433
"Arbuckle Limestone, Physical Characteristics

of," 433
Atoka County, limestone of, uses, 433
bituminous rock sold in, data, 482
Coal County, crushed sandstone of, 486

limestone of, uses, 433
Comanche County, limestone of, uses, 433
crushed granite sold in, 475
crushed-limestone industry, 432
crushed-stone industry, 486
Greer County, crushed-stone industry, 486
limestone of, 432
monumental granite of, 142
Murray County, limestone of, uses, 433
Osage County, limestone of, uses, 433
Pittsburg County, limestone of, uses, 433
Pontotoc County, cement plant, 433
Rogers County, road-stone production, 433
Tulsa County, limestone of, uses, 433
Washington County, cement plant, 433
Onysette, deposit of, 332
Onyx marbles, composition, 169
deposits of, 203, 204, 205, 206, 329

Onyx marbles, foreign, deposits of, 331
imports, table showing, 225

"Onyx Marbles: Their Origin, Composition, and
Uses," 227

Oolitic limestone, definition, 34

Open-pit quarrying {see Quarrying, open pit)

Orange Free State (see Africa, sandstone of)

Oregon, Baker County, limestone of, uses, 434
basalt sold in, 477
Benton County, riprap quarries, 487
Clackamas County, cement plant, 434

riprap quarries, 487
Clatsop County, basalt of, 487
Columbia County, crushed-stone industry, 487
Coos County, sandstone of, uses, 487
crushed sandstone sold in, 476
crushed-stone industry, 433, 486

production data, 486
Douglas County, basalt quarries, 487
Jackson County, limestone of, uses, 434

riprap quarries in, 487
Josephine County, limestone of, uses, 434
Klamath County, basalt quarries, 487
Lane County, basalt quarries, of, 487
limestone of, 433

Linn County, riprap quarries, 487
Multnoma County, riprap quarries, 487
Murray County, asphaltic sandstone of, 486
Sherman County, riprap quarries, 487
Tillamook County, riprap quarries, 487
Wallowa County, crushed-stone industry, 486,
487
lime plant, 434
Wasco County, riprap quarries, 487
Washington County, riprap quarries, 487

sandstone of, uses, 487
Yamhill County, riprap quarries, 487

Ornamental stones, foreign, discussion, 301

Orton, Edward, Jr., 471

Overburden, depth, 13
determination, 13
disposal, 17
nature, 13
utilization, 16

"Overburden, When to Strip," 19

Oxidation, of minerals, effect on stone, 351

Oyster shells, production, 384
uses, 384, 400, 404, 443, 446

Ozora district {see Missouri)

Paper manufacture, use of limestone in, 393

Parallel connection, for electric detonators, dia-
gram, 458

Parian marble {see Greece)

Parker, R. Montgomery, 341

Parks, Bryan, 228

Parks, W. A., 29, 169, 227, 340

Parnisari, Carlo, 341

Paving blocks, manufacture, 70, 156
varieties used for, 25

Peach Bottom district (see Maryland, Harford
County; Pennsylvania, Lancaster and York
Counties)

Pegmatite, definition, 109

INDEX

511

"Pegmatites," 109

Pen Argyl-Windgap district {see Pennsylvania)
Pencil stone (see Agalmatolite)
Pennsylvania, Adams County, crushed-stone
industry, 487, 488

limestone of, uses, 436, 438
Allegheny County, cement plants, 436
Armstrong County, crushed-stone industry, 439
Bangor district, soft-vein slate of, 246
basalt sold in, 477
Beaver County, sandstone of, 78
Bedford County, limestone of, uses, 437, 439
Belfast-Edelman district, hard-vein slate of, 245
Berks County, crushed-stone industry, 487, 488

limestone of, 43, 436, 438

monumental granite of, 140
Blair County, crushed-stone industry, 438, 488
bluestone production, 99
Bucks County, building granite of, 141

crushed-stone industry, 487, 488

monumental granite of, 140
Butler County, limestone of, uses, 436, 437, 439
cement industry, 435
Center County, floe rock of, 488

limestone of, uses, 437, 439
Chapman Quarries district, hard-vein slate of,

245
Chester County, building granite of, 141

building sandstone of, 78

gneiss quarries, 487

limestone of, uses, 436, 437

meerschaum of, 346

monumental granite of, 140

serpentine of, 206
Clarion County, crushed-stone industry, 439
Clearfield County, sandstone of, 78
Clinton County, crushed-stone industry, 439
Columbia County, limestone of, uses, 437, 438
crushed granite sold in, 475
crushed-limestone industry, 434

production data, 435
crushed sandstone sold in, 476
crushed-stone industry, 487

Cumberland County, crushed-stone industry,
438

limestone of, 43
Dauphin County, building sandstone of, 78

limestone of, uses, 436, 438

sandstone-crushing plants, 487
Delaware County, building granite of, 141

crushed-stone industry, 487

meerschaum of, 346
Fayette County, crushed-stone industry, 488
fluxing limestone of, production, 391
Franklin County, crushed-stone industry, 438

limestone of, 43
granite of, description, 140

production data, 140
Greene County, building sandstone of, 78
hard-vein slate district, quarry methods, 265
Harrisburg, limestone construction, 43
Hummelstown brownstone of, 78
Huntington County, crushed-stone industry.

439, 488
Indiana County, crushed-sandstone industry,
488

Pennsylvania, Lackawanna County, crushed-
sandstone industry, 488
Lancaster County, cocalico stone of, 71

crushed-stone industry, 487, 488

limestone of, uses, 437, 438

slate of, 249

quarry methods, 266
Lawrence County, ganister of, 488

limestone of, uses, 436, 437, 439

sandstone of, 78
Lebanon County, limestone of, uses, 437, 438
Lehigh County, limestone of, 43, 436, 438

slate of, 243

quarry methods, 263

soft-vein slate belt of, 235
limestone of, 42, 434, 435, 471

production data, 43, 435
Luzerne County, sandstone quarries, 488
Lycoming County, limestone of, uses, 437, 439

road-stone quarries, 488
Mifflin County, floe rock of, 488

limestone of, uses, 437, 439
Montgomery County, building granite of, 141

crushed-stone industry, 487, 488

limestone of, 43, 436, 437

marble of, 206

mica schist of, 488

quartzite building stone of, 78
Montour County, limestone of, uses, 437, 438
Northampton County, limestone of, 43, 436,
437, 438

slate of, 243, 288

geologic structure, 253
quarry methods, 262
diagrams, 262, 263

Boft-vein slate belt of, 235
Northumberland County, crushed-sandstone
industry, 488

lime industry, 437
open-pit slate quarries, depth, 18
Peach Bottom district, slate of, structure, 253
Pen Argyl-Windgap district, soft-vein slate of,
246

view, 247
Perry County, crushed-stone industry, 438
Philadelphia County, building granite of, 141

gneiss quarries, 487
Pike County, bluestone of, 78

crushed-sandstone industry, 488
sandstone of, 78
slate of, 243

geology, 244

quarrying, floor breaks in, 260
Slatington district, soft-vein slate of, 248
Somerset County, crushed-stone industry, 439
Susquehanna County, bluestone of, 78
Westmoreland County, crushed-stone industry,

439, 488
Wyoming County, bluestone of, 78
York County, limestone of, uses, 436, 437, 438

marble of, 206

slate of, 249

quarry methods, 266
"Pennsylvania, Building Stones of, 66, 102

•512

THE STONE INDUSTRIES

"Pennsylvania, Mining and Crushing Methods
at West Penn Cement Company Limestone
Mine," 471
"Pennsylvania, Northampton County, Observa-
tions on Structures in Slates of," 288
"Pennsylvania, Peach Bottom Slate Deposits,"

232
"Pennsylvania, Silica Refractories of," 492
"Pennsylvania, Slate in," 288
"Pennsylvania Slate Belt, Geologic Factors in

Development of Eastern," 288
Pentelic marble (see Greece)
Peppel, S. v., 471
Phenix district {see Missouri)
Physical agencies, effect on stone, 353
Pipestone (see Catlinite)
Piston drills, use, in crushed-limestone quarries,

453
Pit and Quarry, 19, 471
"Pit and Quarry Handbook," 471
Plant growth, effect on stonework, 357
Poland, marbles of, 330
Pop-shooting method of blistering, description,

459
Porosity, definition, 173

variations, relation to durability, 28
Porphyry, deposits of, 346

uses, 346
Portland brownstone {see Connecticut)
Portland cement, composition, 387

origin of term, 308
"Portland Cement from Marl, Manufacture of,"

471
Portland stone {see England, Dorset)
Portugal, marbles of, 327

slate of, 338
Potsdam sandstone {see New York)
Potstone {see Soapstone)
Poultry grit, preparation, 384

production, 384
Power shovels, in loading quarried crushed lime-
stone, 459, 460, 461
view, 460

for stripping, 16
Preservatives, for stone, discussion, 360
Prices, American marbles, 226

foreign marbles, 226

granite, 167

slate, summary, 287
Production costs, factors affecting, 9
Products, synthetic, competition from, 9
Prospecting, bibliography, 19

method of, selection, 11
Prouty, W. F., 200, 228
Puerto Rico, marbles of, 206
Pulpstones, manufacture, 96
Pumice, use as building material, 344
Purdue, A. H., 289
Pyrite, as impurity in marble, 176
Pyrophyllite, uses, 342

"Quality of Bluestone in Vicinity of Ashoken

Dam," 97
Quarry cars, deecription of, 463

"Quarry Costs, Study of," 467, 492
Quarry Managers' Journal, 341, 471
"Quarry Operation, Round-Table Discussion of,"

19
Quarry and Roadrrmking, 471
Quarrying, open pit, methods, 17

{See also Bluestone; Crushed limestone;
Crushed stone; Granite; Limestone; Mar-
ble; Sandstone; Slate; Soapstone)
Quartz, uses as ornament, 346
Quartz diorite, deposit of, 142
Quartzite, definition, 67
Quincy granite (see Massachusetts, Norfolk

County)

Railroad ballast, requisites, 380

Random ashlar, definition, 24

Reamer, definition, 145

Red marbles, deposits of, 317, 324, 325, 326, 327,

328
Reeds, definition, 81

occurrence, 98
Refractories, use of dolomite for, 394

quantity, 395
"Reliance Cement Rock Quarry, etc.. Mining,

Crushing, and Grinding Methods," 471
Renwick, R. G., 228, 325, 341
Replacement, of minerals, effect, 350
Rhode Island, Bristol County, granite quarries,
488
crushed granite sold in, 475
crushed-stone industry, 488
granite of, description, 139
drilling rate, 145
haulage methods, 155
production data, 139
subdividing blocks, view, 152
wedging method, modification, 153
limestone of, 439

Newport County, granite quarries, 488
Providence County, crushed-limestone indus-
try, 439
serpentine rock, use for road building, 488
soapstone of, 291

Washington County, crushed granite of, 488
granite of, 139
Rhyolite, deposits of, 133
Ribbons, definition, 234
Richardson, C. H., 66, 102, 167, 228, 289
Rift, definition, 81, 108, 173
Riprap, use, 380

"Road-building Rock, Physical tests of," 380
Road stone, requisites, 380
Rochester district (see Vermont)
Rock Products, 19, 471

acknowledgment, 386
Rock products, diversification, 8
"Rock Products Industry, Directory of," 470
"Rock Products, What State Geological Surveys

Are Doing for," 19
" Rock Quarrying for Cement Manufacture," 470
Rockport granite (see Massachusetts, Essex
County)

INDEX

513

Rocks, classification, 6
definition, 5
distribution, 7
igneous, definition, 6

occurrence in United States, 7
metaniorphic, definition, 6

occurrence in United States, 7
relation to minerals, 5
sedimentary, definition, 6
utilization, factors governing, 8
"Rocks, Rock-Weathering, and Soils," 349, 368
Roofing gravel, production, 385
Roofing slate, grading, 283
manufacture, description, 268
mill method, 270

diagram, 272
shanty method, 269
view, 271
production, 238, 239
qualifications for use, 235, 273
sizes, table, 270
storage, 273
"Roofing-Slate Industry, Consumption Trends

in," 288
Roxbury district (see Vermont)
Royalties, computation, 31, 375
Rubber, manufacture, use of limestone in, 393
Rubble, definition, 25
Rumania, alabaster of, 343

marbles of, 330
Run, definition, 81, 98, 108
Rush, D. B., 19
Rushmore Mountain memorial (see South

Dakota)
Russia, amazonite of, 343

malachite of, 345
Ryan, C. W., 295

St. Cloud district {see Minnesota)

Salem limestone (see Indiana, Salem limestone)

Sand blast cleaning, disadvantages, 363

Sand pumps, use, 93

Sandstone, ashlar, use of, view, 77

asphaltic, deposit of, 479, 481, 485, 486, 489

bibliography, 102

bituminous (see Sandstone, asphaltic)

blasting methods, 85
Knox system, 85

as building stone, use, 70

cementation, 68

channeling, discussion, 83
sketch, 84

color, 69

composition, 67

crushed, production, 371, 476

cutting, 96

definition, 67

dimension, production data, 72

discussion, 67

drilling, description, 84

foreign, deposits of, 309

grains, characteristics, 68

indurated, quarry methods, 82

Sandstone, industry, discussion, 67
by states, 73
waste in, prevention, 102
utilization, 101
porosity, 69

quarrying, costs (see " Quarry Costs, Study of")
haulage, 91

methods, discussion, 80
waste, 101
rock structures, effect on quarry methods, 80
sawing, rate, 93
sawmills, operation, 92
soft, quarry methods, 82
uses, 70

as abrasive, 71
as curbing, 70
miscellaneous, 71
as street paving, 70
varieties, 67
weathering effects, 359
"Sandstone Quarrying in the United States," 102
Scabbling, definition, 53, 216
Schaffer, R. J., 368
School slates, manufacture, 274

trimming, saw for, sketch, 274
type of slate needed for, 235
Scotland, granite of, 312

granite workers of, surface-finishing, methods,

162
sandstone of, 310
slate of, 336
Sculp, definition, 233
"Selling a Prospect," 19

Series connection, for electric detonators, dia-
gram, 458
Serpentine, deposits, 205, 206

derivation, 170
Settlement, effect on stonework, 357
Sewage filter beds, use of limestone in, 383
Sewell, John Stephen, 228

Shanty method of manufacturing roofing slate,
description, 269
view, 271
Shearer, H. K., 289
Shedd, Solon, 472
Sheeting planes, definition, 108
Shell marble, deposits, 325
Shot firing, methods, 86
Siebenthal, C. E., 65
Siena marble (see Italy)
Silica, as impurity in marble, 176
Single-bench quarrying, advantages, 456
Slate, bedding, 232
bibliography, 288
chemical composition, 230
color, 231
definition, 229
durability, 232
electrical resistance, 232
exports, destination, 287
value, 286
table, 287
flooring, use, 279
flour, uses, 236
foreign, deposits of, 333
general distribution, 237

514

THE STONE INDUSTRIES

Slate, grain, 233

granules, manufacture, flow sheet, 280

use, 279
history, 237
imperfections, 234
imports, sources, 286
industry, discussion, 229
history, 236
by states, 239
marbleizing, description, 278
marketing, 284
mill, flow sheet, 278
mineralogical composition, 230
mining, description, 266, 337
origin, 229

physical properties, 231
porosity, 232
prices, 287

production, tables, 238, 239
quarrying, blasting, 254
blocks, raising, 260
subdivision, 260
channeling, 255
drilling, 254
general plan, 252
hoisting, 261
methods, 261

diagrams, 262, 263, 266
view, 264
stripping methods, 253
waste utilization, 280
wedging, 254

wire saw, diagrams, 255, 256
use, 255
views, 257, 258
yard transportation, 268
specifications, 283
strength, 231
structural features, 232
tariff, 287
tests, 283
uses, 235
walks, use, 236
weathering effects, 359
" Slate Belt of Eastern New York and Western

Vermont," 288
"Slate, Characteristics of," 288
"Slate Industry, System of Accounts for," 286,

288
"Slate, Physical Properties and Weathering

Characteristics of," 29, 368
"Slate Roofs," 284, 288

"Slate, Scientific Method of Quarrying," 338
"Slate and Slate Quarrying, Treatise on," 340
"Slate, Technology of," 288
Slate Trade Gazette, 341
"Slate in the United States," 288
"Slate, Weathering of," 368
Slatington, district (see Pennsylvania)
Slaty cleavage, definition, 233
Sligh, W. H., 29, 65, 288, 368
Smith, E. L., & Co., acknowledgment, 149, 153
Smith, Eugene A., 472
Smith, R. A., 472
Snow, use as building material, 346

Snubbing, definition, 99

Soap solutions, for cleaning stone, disadvantages,

364
" Soapstone," 295
Soapstone, bibliography, 295

composition, 290

history, 290

industry, discussion, 290

marketing, 294

milling, description, 293
view, 293

occurrence, 292

origin, 292

production, 291

properties, 290

quarrying, methods, 292

uses, 291
Sodalite, deposits of, 347

Sodium chloride, in sea spray, effect on stone, 352
Solvay process, description, 391
"South, Granite, Marble, and Other Building

Stones of the," 226
South Carolina, Chesterfield County, granite
quarry, 489

crushed granite sold in, 475

crushed-stone industry, 489

Edgefield County, riprap quarry, 489

Fairfield County, biotite granite of, 142
granite quarries, 489

Greenville County, road-stone quarries, 489

Lexington County, granite quarries, 489

limestone deposits, 440

Pickens County, road-stone quarries, 489

Richland County, granite quarries, 489
South Dakota, crushed granite sold in, 475

crushed-limestone industry, 440

crushed sandstone sold in, 476

crushed-stone production, 489

Custer County, lime production, 440

Fall River County, building sandstone of, 79
lime production, 440

granite production, 141

Grant County, granite of, description, 141

Hanson County, sandstone of, uses, 489

Lawrence County, lime production, 440
porphyry of, use, 489

limestone of, 440

Minnehaha County, ciuartzite building stone
of, 79
sandstone of, uses, 489

Pennington County, granite of, uses, 489
limestone of, uses, 440

Rushmore Mountain memorial, 141
South Greenfield district (see Missouri)
"Southeastern Atlantic States, Granites of," 167
Spain, alabaster of, 343

Catalonia, marbles of, 327

marbles of, 32G, 341

meerschaum of, 346

slate of, 339
Specific gravity, determination, 29
Square, definition, 235
Statuary marbles, deposits of, 319, 324, 330

value, 178
Steam cleaning, of stone, advantages, 366
"Steam-Shovel Mining," 471

INDEX

515

steel, wear on, in channel cuts, 83
Steidtmann, Edward, 471, 472
Stock food, crushed limestone in, 394
Stoddard, B. H., 295
Stone, 228, 341, 470, 492
Stone, definition, 5

industry, extent, 3
major divisions, 3

selection, care in, importance, 359

used in industry, varieties, 4

used in manufacturing, treatment, 4
(See also Crushed stone)
Stone, R. W., 19, 66, 102
Stone Mountain (see Georgia)
"Stone Setting," 368
"Stones for Building and Decoration," 12, 29,

103, 227, 340, 344. 347, 368
Stonework, deterioration, 348

causes, outline, 349
Stout, Wilbur, 470

Strength, relation to crushing load, 28
Stripping, avoidance, by underground mining, 17

bibliography, 19

clean, importance, 14

difficulties, caused by erosion cavities, 14

discussion, 13

methods, description, 14
"Stripping Methods at Pits and Quarries," 10
"Stripping a Stone Quarry," 19
Struco slate, description, 279
Structural slate, type of material needed, 236
Stucco, preparation, 384
Stylolites, origin, 186
Sugar refining, use of limestone in, 392
Sulphur dioxide, as solvent, effect, 350
Surfacing, applications, 384
Swanton district (see Vermont)
Sweden, granite of, 314
exports, 315
imports, 166

marbles of, 330

slate of, 340
"Swiss Cippolino Marble," 341
Switzerland, granite of, 316

marbles of, 327

slate of, 339
Syene, deposits of, 316
Syenite, deposits of, 314, 316

weathering effects, 359

"Talc and Soapstone," 295
Tampa limestone (see Florida)
Tariff, on granite, 167

on marble, 226

on slate, 287
Tate district (see Georgia, Pickens County)
Taylor, T. G., 492

Technical carbonate, use of dolomite in, 395
Tennessee, Bays Mountain belt, marbles of, 184

Black Oak belt, map, 182
marbles of, 182

Carter County, limestone of, uses, 441, 442

Coffee County, limestone of, uses, 441, 442

Tennessee, Concord belt, map, 182
marbles of, 183, 184
crushed-limestone industry, 441

production data, 441
crushed sandstone sold in, 475
Cumberland County, limestone of, uses, 441,
442
quartzite of, 79
Davidson County, limestone of, uses, 441, 442
Dickson County, lime manufacture, 441
Franklin County, limestone of, uses, 441, 442
French Broad belt, map, 182

marbles of, 183
Friendsville area, map, 182

marbles of, 185
Hamilton County, limestone of, uses, 441, 442
Hickman County, fluxing-stone production, 442
Houston County, lime manufacture, 441
Knox County, limestone of, uses, 441, 442
Knoxville belt, map, 182

marbles of, 183, 185
limestone of, 440
Luttrell belt, map, 182
marbles of, 182, 184
marbles of, characteristics, 186
description, 181
distribution, 181
map, 182

physical properties, 187
production, 181
Marion County, cement plant, 441
Maury County, limestone of, uses, 441, 442
Meadow belt, marbles of, 184 •

Monroe County, slate of, 252
Montgomery County, limestone of, uses, 441,

442
Neubert Springs area, map, 182

marbles of, 186
Roane County, limestone quarry, 442
Sullivan County, limestone of, uses, 441, 442
Washington County, road-stone production,

442
Williamson County, limestone quarries, 442
Wilson County, crushed-stone production, 442
"Tennessee, East, Marbles of," 181, 227
Tenney, J. B., 228
Terrazzo, preparation, 384

Texas, Angelina County, sandstone of, use for
breakwaters, 489
basalt sold in, 477

Bexar County, limestone of, uses, 443, 444
Bee County, caliche of, 489
bituminous rock sold in, data, 482
Brewster County, black marble of, 206
Brown County, ballast production, 443
Burnet County, building granite of, 141

riprap of, 489
Camp County, rock of, use for road construe^

tion, 489
Cedar Park, travertine of, 44
Comal County, limestone of, uses, 443
Coryell County, lime production, 443
crushed granite sold in, 475
crushed-limestone industry, 443

production data, 443
crushed-stone industry, 489

516

THE STONE INDUSTRIES

Texas, Dallas County, cement plants, 443
Duval County, caliche of, 489
Eastland County, crushed-limestone produc-
tion, 443
El Paso County, caliche of, 489

limestone in, uses, 443
Gillespie County, monumental granite of, 142
granite of, description, 141

production data, 141
Harris County, cement plants, 443
Howard County, lime plant, 443
Hudspeth County, caliche of, 489
Jack County, crushed-limestone production,

443
Jones County, crushed-limestone production,
443
limestone of, 43
Kinney County, asphalt-bearing limestone of,
444
limestone of, 43
limestone of, 43, 442

Llano County, monumental granite of, 141
McLennan County, cement plant, 443
Martin County, volcanic tuff of, 489
Milam County, road-material production, 444
Navarro County, crushed-limestone produc-
tion, 443
Palo Pinto County, crushed-limestone produc-
tion, 443
San Patricio County, rock of, 489
Shakelford County, crushed-limestone produc-
tion, 443
Sutton County, road-material production, 444
Tarrant County, cement plant, 443
Travis County, lime plants, 443
Uvalde County, asphalt-bearing limestone of
444
trap rock of, use as railroad ballast, 489
Walker County, sandstone of, uses, 489
Williamson County, lime plants, 443

limestone of, 43
Wise County, crushed-limestone production,
443
"Texas Granites," 167

"Texas, Method and Cost of Quarrying Limestone
Trinity Portland Cement Co., Fort Worth,"
471
"Texas, Mining and Crushing Costs at Tiffin

Limestone Quarry, Fort Worth," 470
Texture, definition, 27
Thoenen, J. R., 467, 468, 472, 492
Through the Ages, 228
Tobacco stains, removal, 367
Tonnage, determination, importance, 457
Tools, for cutting granite, description, 157

sketch, 158
"Top Soil Removed by Two Clever Excavating

Schemes," 19
Trade names (see States and countries named)
"Trade Names and Descriptions of Building
Stones Quarried in the United States,
Canada, and Other Countries," 227, 340
Trainer, David W., Jr., 472
Trainor, Leo S., 358
Translucence, definition, 172
Transportation facilities, availability, 9

"Transvaal, Ornamental Building Stones of," 341
Trap rock, production data, 477

quarry costs (see "Quarry Costs, Study of")
Travertine, composition, 34

deposits, description, 43

origin, 170
Tripod drills, use, 84
Tripoli, use as filter blocks, 344
Tufa, calcareous, deposit of, 307

composition, 34
TufiFs, volcanic, deposits of, 142
Tunnel blasting, description, 456

" Union of South Africa, Building Stones of," 341
Union of South Africa, granite of, 316

slate of, 340
United States, basalt rock sold in, 477
bituminous rock sold in, 482
Bureau of Standards, 392
crushed granite sold in, 475
crushed limestone sold in, 378
crushed sandstone sold in, 476
crushed-stone industry, discussion, 473
crushed stone sold in, graph, 372
granite of, distribution, 112

map, 113
iron furnaces, consumption of flux, 390
limestone of, 37, 396

map, 397
limestone belt, extent, 388
marbles of, 178

map, 179
meerschaum of, 346
rocks in, distribution, 7
sandstone of, 73
slate, districts, list, 237
map, 238
industry, history, 237
review, 239
soapstone of, 292
early uses, 290
production, 291
Tariff Commission, 167
travertine of, 43
"United States, Physical and Chemical Tests of

Commercial Marbles of," 29, 227
"United States, Physical Properties of Principal
Commercial Limestones Used for Building
Construction in the," 29, 65
"United States, Portland Cement Materials and

Industry in," 471
"United States, Sandstone Quarrying in the," 492
" United States, Slate in the," 239
Unsoundness, definition, 174
Utah, bituminous rock sold in. 482

Box Elder County, limestone of, uses, 444, 445
Cache County, limestone of, uses, 444, 445
Carbon County, asphalt sandstone of, quarry-
ing, 489
crushed granite sold in, 475
crushed-limestone industry, 444
crushed-stone industry, 489
Duchesne County, meerschaum of, 346
Iron County, lime industry, 444

INDEX

517

Utah, limestone of, 43, 444

use for refining beet sugar, 392
Morgan County, limestone of, uses, 444, 445
Salt Lake County, granite of, 142
limestone of, uses, 444, 445
rock of, use as roofing granules, 490
San Pete County, limestone of, 43
Sevier County, limestone of, uses, 444
slate of, 252

Tooele County, limestone of, uses, 444, 445
Utah County, limestone of, uses, 444, 445

marbles of, 206
Weber County, lime manufacture, 444

Venezuela, marble of, 331

Verde antique, deposits of, 194, 198, 202, 205, 206,

328
derivation, 170
unsoundness in, cause, 175
Vermont, Addison County, limestone of, uses of, 445
Caledonia County, monumental granite of, 114
Chittenden County, limestone of, uses, 445
Clarendon district, marble quarry, 190
crushed granite sold in, 475
crushed-limestone industry, 445
crushed-stone industry, 490
Dorset Mountain district, marble quarries, 190
Franklin County, limestone in, uses, 445
granite of, block quarries, separation of large
masses, 150

channeling in, view, 149

composition, 103

deep holing, 152
view, 153

description, 114

drilling rate, 145

production data, 114

quarrying, view, 144
Isle La Motte district, marble quarry, 193
limestone of, 445
marbles of, beds in, succession, 189

discussion, 187

geologic features, 188

production data, 187

quarry districts, 190
Orleans County, mica schists of, uses, 346

monumental granite of, 115
Rochester district, serpentine quarry, 194
Roxbury district, verde antique quarry, 194
Rutland County, limestone of, uses, 445

slate of, quarry methods, 265
diagram, 265
slate of, description, 241, 243

hoisting methods, 261

production data, 241

quarrying, floor breaks, 260

structure, 253

waste, in quarrying, 280
soapstone of, 291

Swanton district, marble quarries, 193
"verde antique" (see Vermont, Rochester

district)
Washington County, granite waste, use as
by-product, 490

Vermont, Washington County, monumental
granite of, 115
West Rutland districts, quarries, 190

view, 191
Windham County, agricultural limestone
production, 445
granite waste, uses, 490
monumental granite of, 116
Windsor County, granite waste, uses, 490
limestone of, uses, 445
monumental granite deposits, 116
" Vermont, Eastern, Calcite Marble and Dolomite

of," 227
"Vermont, Western, Commercial Marbles of,"

187, 189, 227
Vermont Marble Company, acknowledgment,

191, 218, 220, 221
Virginia, Albemarle County, crushed-granite
production, 490
slate of, 251
soapstone of, 291
Alleghany County, crushed-limestone produc-
tion, 447
Amelia County, amazonite of, 343

soapstone of, 292
Arlington Cemetery, Tomb of Unknown

Soldier, construction, 205
Augusta County, crushed-sandstone produc-
tion, 490
limestone of, uses, 446, 447
basalt sold in, 477

Bath County, road-stone production, 447
Botetourt County, limestone of, uses, 446, 447
Buckingham County, slate of, 250
quarry methods, 267
structure, 253
crushed granite sold in, 475
crushed-limestone industry, 446

production data, 446
crushed sandstone sold in, 476
crushed-stone industry, 490
Culpepper County, crushed-granite production,

490
Fairfax County, soapstone of, 292
Fluvanna County, slate of, 250
Franklin County, soapstone of, 292
Frederick County, limestone of, uses, 446
Giles County, limestone of, uses, 446, 447
Goochland County, crushed-stone industry, 490
Greensville County, granite of, use for railroad

ballast, 490
Henrico County, crushed-stone industry, 490
Henry County, soapstone of, 292
Lee County, limestone quarries, 447
limestone of, 445
limestone fences, view, 299
Loudon County, limestone of, uses, 446

trap rock of, 490
Lynchburg, greenstone at, 295
microcline of, 343

Montgomery County, Brush Mountain stone
of, 71
lime production, 446
Mount Vernon, construction, 310
Mount Vernon Highway, bridges, construction,
138

518

THE STONE INDUSTRIES

Virginia, Nelson County, soapstone of, 291
mills near deposits, view, 293
Orange County, soapstone of, 292
Prince William County, sandstone of, 79
Pulaski County, crushed-limestone production,

447
Roanoke County, crushed-limestone produc-
tion, 447
Rockbridge County, railroad-ballast produc-
tion, 447
Rockingham County, black marble of, 200

limestone of, uses, 44G, 447
Scott County, limestone quarry, 447
Shenandoah County, limestone of, uses, 446,

447
Smyth County, limestone for alkali manufac-
ture, quarrying, 447
State Capitol, slate roof, 237
Stafford County, building sandstone of, 79
Tazewell County, limestone of, uses, 446, 447
Warren County, limestone of, uses, 446, 447
Wythe County, crushed-limestone production,
447
"Virginia, Origin of Talc and Soapstone Deposits

of," 295
"Virginia, Soapstone Mining in," 295
" Virginia, Stripping Clay from Seams and Pockets
in the Shenandoah Valley of," 19

Wagner, Percy A., 341
Wales, marbles of, 329
slate, description, 333
quarrying, 334
"Wales, Slates of," 288, 333, 340
Walks, type of slate used, 236
Wallace, R. C, 341

Warnes, A. R.. 228, 341, 349, 353, 366, 368
Washington, basalt sold in, 477

Benton County, crushed-basalt production, 490

Chelan County, sandstone of, 490

Columbia County, crushed-basalt production,

490
Cowlitz County, crushed-basalt production, 490
crushed granite sold in, 475
crushed-limestone industry, 448

production data, 448
crushed sandstone sold in, 476
crushed-stone industry, 490
Douglas County, sandstone of, 491
granite production, 142

Grant County, crushed-basalt production, 490
King County, cement mills, 448

crushed-basalt production, 490
Kitsap County, crushed-basalt production, 490
Kittitas County, crushed-basalt production,

490
Klickitat County, crushed-basalt production,

490
Lewis County, crushed-basalt production, 490
limestone of, 447
Okanogan County, crushed-basalt production,

490
Pacific County, crushed-basalt production, 490

Washington, Pend Oreille County, cement mill,
448
crushed-basalt production, 490
Pierce County, riprap production, 491

sandstone of, 79
San Juan County, limestone of, uses, 448
Skagit County, cement mill, 448
Snohomish County, granite of, 142
Spokane County, cement mill, 448
crushed-basalt production, 490
monumental granite of, 142
Stevens County, lime industry, 448

multicolored marble, 206
Thurston County, sandstone of, 79
Walla Walla County, crushed-basalt produc-
tion, 490
Whatcom County, limestone of, uses, 447, 448
Whitman County, crushed-basalt production,

490
Yakima County, crushed-basalt production,
490
"Washington, Cement Materials in Industry in

the State of," 472
"Washington, Road Materials of," 492
Waste, in granite quarrying, disposal, 155
in limestone quarrying and milling, 63
in marble quarrying, 223
in sandstone industry, 101
in slate quarrying, 280
Water, scrubbing with, for cleaning stone, dis-
advantages, 364
" Waterproofing Materials, Exposure Tests cm

Colorless," 368
Waterproofing methods, discussion, 361
Watson, John, 228
Watson, T. L., 167
Weathering, effect on stone, 352
"Weathering of Natural Stone, Bibliography (m,"

368
"Weathering Test Procedures for Stone," 368
Wedges, types, description, 88
Wedging, discussion, 88
Weigel, W. M., 210, 228
West Rutland districts (see Vermont)
West Virginia, Berkeley County, limestone of,
uses, 449
crushed-limestone industry, 449

production data, 449
crushed sandstone sold in, 476
crushed-stone industry, 491

Greenbrier County, crushed-limestone produc-
tion, 450
Jackson County, abrasive sandstone of, 79
"Jefferson, Berkeley, and Morgan Counties,"

449
Jefferson County, limestone of, uses, 449
Kanawha County , crushed-stone production , 49 1
limestone of, 448
Monongalia County, abrasive sandstone of, 79

crushed-limestone production, 450
Morgan County, ganister production, 491
Ohio County, crushed-limestone production,
450
crushed-stone production, 491
Preston County, building sandstone of, 79
limestone of, uses, 449, 450

INDEX

519

West Virginia, Wayne County, limestone of, uses,

449
Wet processes, for cleaning stone, description, 364
Whiting, definition, 382

substitutes, 382 ^

use of limestone as, 382
uses. 382
Williams-Ellis, M. I., 341
Wind action, effect on stone, 356
Wire brushing, disadvantages, 363
Wire saw, opening new floor with, description, 263
diagram, 263
view, 264
savings possible with, 260
use, 210

in quarrying, of limestone, 48, 306
of marble, 204, 319, 324, 330
of sandstone, 74
of slate, 255, 338
diagrams, 255, 256
views, 257, 258
" Wire Saw in Marble Quarrying, Application of,"

210, 228
" Wire Saw in Slate Quarrying," 288
"Wire-saw Operation in Europe, Significant

Features," 340
"Wire-saw Tests, Results of," 48
Wisconsin, Ashland County, granite of, 131
basalt sold in, 477
Bayfield County, sandstone of, 79
Brown County, limestone of, uses, 450. 451
Buffalo County, crushed-limestone production,

451
Calumet County, limestone of, uses, 450, 451
crushed granite sold in, 475
crushed-limestone industry, 450

production data, 450
crushed sandstone sold in, 476
crushed-stone industry, 491
Dodge County, limestone of, uses, 450, 451
Dunn County, sandstone of, 79

sandstone-riprap industry, 491
Dunville stone of, 80
Fond du Lac Coiinty, limestone of, uses, 450,

451
granite of, description, 132

production data, 132
Grant County, crushed-limestone production,

451
Green County, crushed-limestone production,

451
Green Lake County, crushed-stone production,
491
rhyolite of, 133
Juneau County, crushed-stone production, 491
La Crosse County, crushed-limestone produc-
tion, 451

Wisconsin, Lafayette County, crushed-limestone
production, 451
Lake Superior brownstone of, 79
limestone of, 43, 450

Manitowoc County, limestone of, uses, 450, 451
Marathon County, monumental granite of, 133
Marinetta County, granite of, 133
Marquette County, granite of, 133
Milwaukee County, crushed-limestone produc-
tion, 451
limestone of, 43
Ozaukee County, limestone of, uses, 450, 451
Pierce County, crushed-limestone production,

451
Polk County, trap-rock quarries, 491
Racine County, crushed-limestone production,

451
St. Croix County, crushed-limestone produc-
tion, 451
Sauk County, crushed-limestone production,
451
quartzite of, uses, 491
Sheboygan County, limestone of, uses, 450, 451
Vernon County, crushed-limestone production

451
Waukesha County, crushed-limestone produc-
tion, 451
limestone of, 43
Waupaca County, granite of, 133
Waushara County, crushed-stone production,
491
granite of, 134
Wood County, miscellaneous stone, use for
highway construction, 491
"Wisconsin, Building and Ornamental Stones of,

28, 167
"Wisconsin, Limestones and Marls of," 472
" Wisconsin, Limestone Road Materials of," 471
Woolf, D. O., 380

Workmanship, faults in, effect on stonework, 357
Wyberg, W., 341

Wyoming, Albany County, cement plant, 452
limestone of, 451
Carbon County, sandstone of, uses, 491
crushed-limestone industry, 452

production data, 452
crushed sandstone sold in, 475
Laramie County, limestone of, 451

for sugar manufacture, production, 452
Platte County, limestone of, 451, 452
Weston County, limestone of, 451

Yellow marble, deposits of, 330
Yugoslavia, marbles of, 329

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