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Full text of "A text-book of important minerals and rocks. With tables for the determination of minerals"

GIFT TO THE LIBRARY 

CIVIL ENGINEERING DEPARTMENT 

UNIVERSITY OF CALIFORNIA 

BY 

PROFESSOR FRANK SOULE 
1912 



L- 




WORKS OF PROF. S. E. TILLMAN 



PUBLISHED BY 



JOHN WILEY & SONS, 



Descriptive General Chemistry. 

A Text-book for Short Course. 8vo, cloth, 
83.00, net. 

Elementary Lessons in Heat. 

Second edition, revised and enlarged. 8vo, 
cloth, $1.50, net. 

A Text-book of Important Minerals and Rocks. 

With Tables for the Determination of Minerals. 
8vo, cloth, 186 pages. $2.00, net. 



A TEXT-BOOK . 



OF 



IMPORTANT MINERALS 
AND ROCKS. 



WITH 

TABLES FOR THE DETERMINATION 
OF MINERALS. 



BY 



S. E. TILLMAN, 

of Chemistry \ Mineralogy, ant 
U. S. Military Academy, West Point, N. Y. 



Professor of Chemistry, Mineralogy, and Geology, 



FIRST EDITION. 
FIRST THOUSAND. 



NEW YORK: 

JOHN WILEY & SONS. 

LONDON: CHAPMAN & HALL, LIMITED. 

1900. 



' -* V: X- ""> " - 




Copyright, 1900, 

BY 
S. E. TILLMAN, 



ROBERT DRUMMOND, PRINTER, NEW YORK. 



PREFACE. 



THIS book is the slow outgrowth of the efforts to meet 
the necessities of this institution for a convenient text-book 
of the important minerals and rocks. The number of min- 
eral species has reached nearly one thousand and is con- 
stantly increasing. Of this number less than one-tenth is of 
common occurrence or can be considered of much economic 
importance, and a small proportion of this same tenth in- 
cludes the essential constituents of all roeks. To embrace 
in descriptive text all mineral species necessarily results in 
an embarrassing mass of matter for the general student. 
Similar embarrassment, though to a less extent, is experienced 
in complete descriptions of all the rocks/ To reduce these 
descriptions to a convenient yet satisfactory form for gen- 
eral students is the object of the present effort. 

There are described in the book about seventy-five dis- 
tinct species of the important and in the main common min- 
erals, and the principal members of the different classes of 
rocks. It is thought that the selection is extended enough 
for general purposes, and it includes abundant material for 
the study of both minerals and rocks. The book is prima- 
rily prepared to meet the necessities of the Military Academy, 
whose students are well fitted for the work when they begin 
it, have excellent opportunity for the examination and com- 
parison of specimens, and for laboratory work in determin- 

iii 



785375 



IV PREFACE. 

ing them. It is hoped that the book may be of conveni- 
ence to a larger class of students whose facilities in the 
study may be less, but whose aim is the same as ours to 
acquire a fair knowledge of the important minerals and 
rocks. 

Chapter I of the book contains in brief outline the more 
fundamental principles of crystallography, followed by a 
description of the different crystalline systems and of some 
of the more important crystalline aggregates and irregular 
forms. The subject-matter of the chapter can be almost 
indefinitely extended by lecture if so desired. The reason 
that the crystallographic branch is so briefly treated is stated 
in the introduction to the book, no other treatment being 
considered appropriate in a short general course. 

Chapter II contains a short description of the general 
properties of minerals, of the laboratory facilities for de- 
termining them, and of the manner of using these facilities. 

In Chapter III an effort has been made to give a concise 
and accurate statement of the more readily observed phy- 
sical properties of the mineral species and of the ordinary 
mineralogical tests for distinguishing and determining them. 
There are also added many desirable facts relating to the 
use and occurrence of the minerals. 

A table for the determination of minerals follows this 
chapter and is intended for a guide and companion in the 
practical examinations and tests of the minerals. 

The table merely puts in condensed form the described 
properties and characteristics of the minerals as given in 
Chapter III. This tabular arrangement has many advan- 
tages over a descriptive text-book without tables, or with 
tables bound in separate form. A statement of the proper- 
ties of each species in the body of the text as well as in the 
table has been found advantageous when recitation and 
practical work are conducted simultaneously. 

The tables have been a slow growth, of nearly twenty 
years, from very simple beginnings, and have during that 
time been used by our pupils under separate binding. In 



PREFA CE. - V 

this preparation I have had valuable suggestions from sev- 
eral officers who have served as instructors in the depart- 
ment, but I would here especially acknowledge my great 
indebtedness to Capt. J. P. Wisser, /th U. S. Artillery, who, 
as Lieutenant Wisser and while serving as Assistant Profes- 
sor in the Department in 1890 and '91, did the larger part of 
the work which placed the tables in their present shape. 

Part II is devoted to the common rocks. The prin- 
ciples of classification, the classes, and the distinguishing 
characteristics of each class are given ; the appearance of the 
different members of each class is described and their min- 
eral composition given, to which are added many important 
facts as to occurrence and use and the more prominent con- 
clusions as to origin. 

The greater portion of the matter contained in the 
book, exclusive of the mineral tables and the contents of 
Chapter I, has been used at the Academy for the past six 
years, and has been frequently added to and revised during 
that time. 

The arrangement of mineral species in the text is mod- 
eled after that of the late Professor J. DrDana in his man- 
ual of Mineralogy and Petrography. The mineral com- 
pounds of the same metals are brought together, except in 
the case of silicates. The important metals and their ores 
are consecutively treated, as are the important rock-making 
minerals. This arrangement has, from experience, been 
found very satisfactory. 

In the preparation of this little book I have consulted 
many authorities, but would especially acknowledge my 
obligations for mineralogical matter to the works of Pro- 
fessors J. D. Dana, E. S. Dana, G. J. Brush, S. L. Penfield, 
H. Bauerman, W. O. Crosby, D. M. Barringer ; for petro- 
graphic material to various published papers of the U. S. 
Geological Survey, to the works of Professors J. F. Kemp, 
W. B. Scott, and J. D. Dana; for the chapter on Crystal- 
lography to the works of Professors G. H. Williams, E. S 
Dana, H. Bauerman, and N. Story Maskelyne. 



of the more important crystalline aggregates cj 
forms. The subject-matter of the chapter a 
indefinitely extended by lecture if so desired, 
that the crystallographic branch is so briefly trej 
in the introduction to the book, no other tre; 
considered appropriate in a short general cour j| 

Chapter II contains a short description oJBp"c 
properties of minerals, of the laboratory facil 
termining them, and of the manner of using th| 

In Chapter III an effort has been made to gj 
and accurate statement of the more readily oti 
sical properties of the mineral species and of 
mineralogical tests for distinguishing and deter 
There are also added many desirable facts re| 
use and occurrence of the minerals. 

A table for the determination of minerals 
chapter and is intended for a guide and comp 
practical examinations and tests of the minerals 

The table merely puts in condensed form t 
properties and characteristics of the minerals 'Wrcii til 
Chapter III. This tabular arrangement has many advan- 
tages over a descriptive text-book without tables, or with 
tables bound in separate form. A statement of the proper- 
ties of each species in the body of the text as well as in the 
table has been found advantageous when recitation and 
practical work are conducted simultaneously. 

The tables have been a slow growth, of nearly twenty 
years, from very simple beginnings, and have during that 
time been used by our pupils under separate binding. In 



PREFA CE. V 

this preparation I have had valuable suggestions from sev- 
eral officers who have served as instructors in the depart- 
ment, but I would here especially acknowledge my great 
indebtedness to Capt. J. P. XVisser, /th U. S. Artillery, who, 
as Lieutenant Wisser and while serving as Assistant Profes- 
sor in the Department in 1890 and '91, did the larger part of 
the work which placed the tables in their present shape. 

Part II is devoted to the common rocks. The prin- 
ciples of classification, the classes, and the distinguishing 
characteristics of each class are given ; the appearance of the 
different members of each class is described and their min- 
eral composition given, to which are added many important 
facts as to occurrence and use and the more prominent con- 
clusions as to origin. 

The greater portion of the matter contained in the 
book, exclusive of the mineral tables and the contents of 
Chapter I, has been used at the Academy for the past six 
years, and has been frequently added to and revised during 
that time. 

The arrangement of mineral species in the text is mod- 
eled after that of the late Professor J. DrDana in his man- 
ual of Mineralogy and Petrography. The mineral com- 
pounds of the same metals are brought together, except in 
the case of silicates. The important metals and their ores 
are consecutively treated, as are the important rock-making 
minerals. This arrangement has, from experience, been 
found very satisfactory. 

In the preparation of this little book I have consulted 
many authorities, but would especially acknowledge my 
obligations for mineralogical matter to the works of Pro- 
fessors J. D. Dana, E. S. Dana, G. J. Brush, S. L. Penfield, 
H. Bauerman, W. O. Crosby, D. M. Barringer ; for petro- 
graphic material to various published papers of the U. S. 
Geological Survey, to the works of Professors J. F. Kemp, 
W. B. Scott, and J. D. Dana; for the chapter on Crystal- 
lography to the works of Professors G. H. Williams, E. S. 
Dana, H. Bauerman, and N. Story Maskelyne. 



VI PREFACE. 

Through the courtesy of Professor E. S. Dana I have 
been permitted to use the crystalline figures shown under 
numbers 2, 3, 4, $, 18, 20, 22, 25, and 26, which are taken 
from his Text-book of Mineralogy. Figures 19, 31, 32, 33, 
and 34 are from Williams's Elements of Crystallography, 
through the courtesy of the publishers, Henry Holt & Co. 

S. E. TILLMAN, 

U. S. MILITARY ACADEMY, WEST POINT, N. Y., 
October i, 1900. 



TABLE OF CONTENTS. 



PART I. 
IMPORTANT MINERALS. 

CHAPTER I. 

ELEMENTS OF CRYSTALLOGRAPHY. 

PAGES 

INTRODUCTORY REMARKS 1-3 

GEOMETRIC SYMMETRY 3-4 

CRYSTALLOGRAPHIC SYMMETRY ~. 4-6 

CRYSTALLOGRAPHIC AXES 6-9 

CRYSTALLOGRAPHIC LAWS 9-10 

CRYSTALLINE SYSTEMS 11-18 

CRYSTAL FORMS 18 

DISTORTIONS IN CRYSTALS 19-22 

CRYSTALLINE AGGREGATES 23-24 

CHAPTER II. 

PHYSICAL AND CHEMICAL PROPERTIES OF MINERALS. 

PHYSICAL PROPERTIES OF MINERALS 25-27 

CHEMICAL PROPERTIES OF MINERALS 27-31 

CHAPTER III. 

DESCRIPTIVE MINERALOGY. 

NATIVE ELEMENTS 32-40 

ORES OF SILVER 40-42 

ORE OF MERCURY 42-43 

COPPER AND ITS ORES 43-48 

ORES OF LEAD. 48- r 

vti 



Vlll TABLE OF CONTENTS. 

PAGES 

ORES OF ZINC 51-52 

ORES OF IRON 53-60 

ORES OF ANTIMONY AND MANGANESE 60-61 

TIN ORE 61 

RARE MINERALS 62-65 

COMPOUNDS OF SODIUM AND POTASSIUM 65-67 

COMPOUNDS OF CALCIUM 67-74 

QUARTZ, SILICA 74-78 

SILICATES 78-94 

M i NERAL COAL 94-96 

DESCRIPTION OF TABLES 96-97 

TABLES FOR DETERMINATION OF MINERALS 98-137 

PART II. 

COMMON ROCKS. 

ROCK CONSTITUENTS 139-140 

CLASSIFICATION OF ROCKS 140-141 

SEDIMENTARY ROCKS 141-152 

IGNEOUS OR UNSTRATIFIED ROCKS 152-158 

TABULAR CLASSIFICATION OF ROCKS 158 

METAMORPHIC ROCKS 159-161 



The following abbreviations are used in the text : 

Before blowpipe B.B. 

Color C. 

Hardness H. 

Luster L. 

Oxidizing Flame , O.F. 

Reducing Flame .^, . . R.F. 

Sign of inequality greater than > 

Specific gravity G. 



PART I. 
IMPORTANT MINERALS. 



CHAPTER I. 
INTRODUCTORY REMARKS. 

THE natural objects of the universe can in general be 
included in two great groups or kingdoms, the organic and 
the inorganic. To the first belong the bodies which origi- 
nate through the agency of life, to the second the bodies not 
thus originating. 

Those bodies occurring in the inorganic kingdom which 
have a definite chemical composition are termed minerals. 
Mineralogy is the science which describes and teaches how 
to distinguish and determine minerals. The distinction of 
minerals from each other is based upon the consideration of 
the composition, external form, and internal structure, all of 
which must be determined and investigated in the full 
classification of minerals. 

The term ' mineral species ' is generally made to include 
all those minerals which have the same composition and a 
definite form and structure. With few exceptions minerals 
at ordinary temperatures are solids, and all minerals in be- 
coming solid, whether from state of vapor, fusion, or solu- 
tion, tend, under favorable conditions, to form regular 
geometrical solids bounded by plane surfaces. The regular 
forms thus assumed by minerals are called crystals. The 
natural bounding-plane surfaces of a crystal are called the 
faces, the lines in which the faces intersect are called edges, 



CR 1 'S TA LLOGRA PH Y. 



the angles between edges are plane angles, those between 
faces are interfacial angles, and those formed by the meeting 
of three or more faces are solid angles. 

In the study of crystal forms it was early observed 

i st. That there was a marked symmetry in the arrange- 
ment of their parts, as faces, edges, points, etc. 

2d. It was discovered that the forms of the same species 
obeyed certain laws that made possible a geometrical classi- 
fication of the crystals of different species. 

It was later developed by studying the physical proper- 
ties of the crystals that there is an intimate and complete 
accord between these properties and the forms of the crys- 
tals, and that the form is but the obvious external evidence 
of a definite internal structure ; that it is the structure that 
is characteristic, the form and physical properties are the 
evidences of the structure. 

The consideration of the properties or characteristics 
which distinguish minerals (structure, form, composition) 
give rise to two distinct divisions of the science of min- 
eralogy. 

I. Crystallographic mineralogy, which considers the 
form and structure of the minerals, and this has two 
branches : 

(a) Geometric or morphological crystallography, which 
considers the external form of minerals and the geometric 
relations of their faces and plane surfaces. 

(b) Physical crystallography, which investigates the 
properties which are mainly the result of structure, i.e., 
physical properties, such as cohesion, elasticity, and the 
properties displayed under the action of light, heat, elec- 
tricity, etc. 

II. Chemical mineralogy, which is primarily concerned 
with determining the chemical composition of the minerals. 
It also extends to the consideration of the chemical relations 
between constitution and form. 

The knowledge obtained through all the above branches 
of mineralogy when systematically arranged and presented, 
together with information as to mode of occurrence, distri- 






ELEMENTS OF GEOMETRIC SYMMETRY. 3 

bution, and association of the different species, constitutes 
Descriptive Mineralogy. 

Thorough acquaintance with all branches of mineralogy 
are essential to the work of specialists, but for the general 
student the essentially chemical branch is far more impor- 
tant, for through it the composition can usually be more 
readily determined, and it is upon the composition that all 
other relations depend. For this reason only brief reference 
will be made in this book to the crystallographic branch, 
and then only to the most fundamental principles. 

CRYSTALLOGRAPHIC CONSIDERATIONS. 

Elements of Geometric Symmetry in the Form of Solids. 

The symmetry of form in solids may be considered with 
reference to planes of symmetry, axes of symmetry, or cen- 
ters of symmetry. 

Planes of Symmetry. The form of a solid is geometri- 
cally symmetrical with reference to a plane when the plane 
divides the solid into two precisely corresponding parts, so 
that every normal to the plane section would meet a cor- 
responding point of the solid at the same distance from the 
section. A polyhedron placed upon a plane mirror forms 
with its image a symmetrical figure, of which the mirror 
surface is the plane of symmetry. Again, a plane passing 
through the center of a cube parallel to either face divides 
it symmetrically, and it is at once evident that there are 
three such planes for a cube. So the planes passing through 
the diagonally opposite edges of a cube are planes of sym- 
metry. There is generally a distinction between the mineral- 
ogical symmetry of crystals and the full geometric sym- 
metry of figure here defined. This distinction will appear 
subsequently. 

Axes of Symmetry. An axis of symmetry of a solid is a. 
line about which if the body be rotated it will successively 
occupy the same position, or will fill the same place in space.. 
Axes of symmetry can be distinguished from each other by 
the number of times the body occupies the same position^ 
during a complete revolution about each. 



CR YS TA LL OCR A PH Y. 



A cube turned about a line joining the middle point of 
opposite faces will occupy the same position four times dur- 
ing one revolution ; such line is an axis 
of quaternary or tetragonal symmetry. 
A line joining the middle points of 
diagonally opposite edges in a cube is 
an axis of binary symmetry. In the 
square octahedron, Fig. I, the vertical 
axis a is an axis of quaternary sym- 
metry, while c and d are axes of binary 
symmetry. The axis about which the 
third or a higher order exists is a 
principal axis of symmetry; other axes 
are secondary axes. 




FIG. i, 



Center of Symmetry. A center of symmetry 
of a solid exists when a line passing through the 
center meets similar points in the opposite halves of the crystal at the 
same distance from the center. A center of symmetry may exist without 
either axes or planes of symmetry being present. 

In every case of a center the crystal polyhedron is bounded by pairs 
of parallel planes which are at equal distances from the center, and it 
can always be shown that the points in which a line through the center 
pierces any two of these planes are corresponding points in two halves 
into which the crystal may be divided. 

Crystallographic Symmetry. Geometric symmetry, above 
referred to, relates to the external form of the solid. In 
crystals, as already stated, the physical properties have a 
definite, constant and most intimate connection with the ex- 
ternal form. Both form and physical properties are deter- 
mined by the structure of the particular body ; the struc- 
ture is the most essential physical character of the crystal, 
and the form is only the most important external mani- 
festation of the structure. A solid in the form of a 
crystal, without the related internal structure, does not 
constitute a crystal ; such a solid is only a model of the ex- 
ternal form. 

Natural crystals very frequently exhibit geometric sym- 



CR YS TA LLOGRA PHIC S YMME TR Y. 



metry in their external form, and it is thought that if crys- 
tallization took place without any disturbance of, or inter- 
ference with, the most favorable circumstances for the 
process, geometric symmetry of form would generally 
result. In such cases crystallographic symmetry would be 
denned by the relations of geometric symmetry which would 
result. Crystallographic symmetry, however, exists with- 
out being completely expressed in the external form. The 
form is but one indication of the internal structure, the 
physical properties are another. The physical character of 
minerals have been very carefully studied, and in general 
are found to be the same in all parallel directions. This 
fact is believed to demonstrate a like internal structure or 
molecular arrangement in these parallel directions. The 
intimate relations between the physical character and the 
faces and planes of a crystal lead to the conclusion that the 
planes are but external expressions of the internal structure. 
The faces are accordingly definitive because of their direc- 
tion or angular position, and not because of their size or 
distance from any assumed origin. Thus Figs. 2 and 3 are 





FIG. 2. 



FIG. 3. 



equally symmetrical about a vertical or horizontal plane 
passing through their centers. Again, a crystal may be a 
crystallographic cube, though departing widely from the 
geometric form, as in Figs. 4 and 5, provided it can be 
shown that the three pairs of faces are alike ; this would 
have to be done from the physical character of the faces, by 
the kind of cleavage, or by optical means. 

The important point to be grasped in regard to crystal- 
lographic symmetry is that the symmetry in crystals about 



CR YS TALLOGRAPHY. 



FIG. 4. 



FIG. 5. 



lines or planes is one of direction and not of position. In 
consequence of this fact any plane of a crystal may be con- 
sidered as shifted parallel to itself without affecting the 
crystallographic symmetry : hence 
the corresponding symmetrical faces 
of a crystal may be of very unequal 
size and distance from the origin, 
without disturbing the crystallograph- 
ic symmetry. In general, for conven- 
ience in the discussion and description 
of forms it is better to consider 
symmetry of position as well as of 
direction ; in other words, we may 
readily imagine the similar crystal 
planes to be shifted in directions parallel to themselves 
until a solid of geometric symmetry is produced. 

Coordinate or Crystallographic Axes. For studying and 
classifying crystal forms, and for describing the position of 
their faces, it is convenient to assume a system of coordinate 
axes after the manner of analytical geometry. Different 
sets of axes may, for this purpose, be assumed in crystals, 
but that set is usually employed which enables expression in 
the simplest manner of the position of the faces and the re- 
lations between different crystalline forms. These consid- 
erations have led to the selection of the axes of symmetry as 
coordinate axes whenever the proper number of these axes 
are present. If only one axis of symmetry is present, it is 
employed in connection with two other assumed directions. 
The axes chosen under the above conditions will differ in 
their relations to each other in different crystalline forms. 
They may intersect at right angles, giving orthometric forms, 
or obliquely, giving clinometric forms. They may be all 
equal in length, only two equal, or all unequal ; in some 
cases they connect the centers of opposite faces, in others 
the middle points of opposite edges, or the apices of oppo- 
site solid angles. It should be remembered that the axes 
usually assumed are not the only ones that could be em- 
ployed, but are such as afford the simplest relations for the 



LOCATION OF PLANES BY REFERENCE TO AXES. 7 

descriptions of forms. The planes in which the coordinate 
axes lie are called the axial or diametric planes. They cor- 
respond to the coordinate planes of analytical geometry, 
and divide the spaces within the crystal into eight solid 
angles, and in one system where four axes are used the 
space is divided into twelve solid angles. 

Location of Planes by Reference to Axes. The position of 
any plane is known when its intercepts on the assumed axial 
directions are given. If #, y, z represent the intercepts on 
the respective axes of a plane, the position of the plane may 
be expressed by x : y : z. The intercepts on the axes are 



FIG. 6. 

called the parameters of the plane. In general the axes are 
lettered a, b, c, the vertical axis usually being represented 
by c, that from right to left b, from front to rear by a ; as in 
analytical geometry, the positions of the semiaxes on oppo- 
site sides of the origin have opposite signs, the plus sign (+) 
being applied to the halves in front, to the right, and above 
the origin, and the minus sign ( ) to the opposite halves, 
Fig. 6. If definite lengths on the axial directions be 
assumed as unit semiaxes, the parameters of any plane may 
be expressed in these lengths. The unit semiaxes assumed 
are those belonging to a particular crystal form of each 



CR YS TA LLOGRA PH Y. 

species. This particular form is called the unit form or 
fundamental form. The unit form and the crystallographic 
axes in the form are so chosen as to give the simplest ex- 
pression for the parameters in the different crystals of the 
species. If we let a, b, and c represent the unit axes, the 
parameters x, y, and z of any plane may be written ma : nb : 
re, which is the general expression for a face. The letters 
m, n y and r are the ratios of the intercepts to the lengths of 
the semiaxes and are called parameter coefficients. It is 
evident that the intercepts of all parallel planes bear the 
same ratio to each other, and since crystallographic sym- 
metry is not affected by shifting a plane parallel to itself, 
one of the intercepts of a plane may always be assumed 
equal to unity, and the general expression for the face 
becomes a : nb \ re. It follows from these considerations 
that all parallel planes lying on the same side of the origin 
have identical expressions ; parallel planes on the opposite 
sides of the origin have the same expressions except as to 
sign. Parallelism to any axis is represented by the sign in- 
finity associated with that axial symbol. Thus a : oo b : oo c 
indicates a plane parallel to two of the axes (b and c}. The 
positions of a plane may also be expressed by using the 
reciprocals of the parameters ; such reciprocals are termed 
indices of the plane. Several systems of notation have beea 
devised, the object in each case being to represent briefly 
and clearly the position of the faces with reference to the 
crystallographic axes. It is not practicable to here describe 
the system of notation. 

Definitions Pertaining to Crystals. Cleavage is the quality 
which minerals possess of splitting in certain definite 
directions along plane surfaces. Cleavage is, of course, a 
result of molecular structure, and a consideration of the 
molecular arrangements in a mineral which would produce 
crystal faces explains also the tendency to cleave in direc- 
tions parallel to the faces. Every cleavage plane is a possi- 
ble face of a crystal, and is due to the molecular arrange- 
ment which produces faces. The more fundamental the 
face the more perfect is the cleavage in that direction. The 



^%^e 



CRYSTALLOGRAPHIC LAW. $. 

natural planes of a crystal are called its faces ; those ob- 
tained by splitting are called cleavage planes. As already 
stated, the intersections of bounding planes are edges. 
When an edge is cut off by a plane it is said to be replaced / 
when the replacing plane is equally inclined to the original 
faces the edge is truncated ; when the edge is cut off by 
two planes equally inclined respectively to the original faces 
it is bevelled. 

Similar planes are those which can be expressed by the 
same notation except as to signs. Similar edges are pro- 
duced by the intersection of corresponding pairs of similar 
planes. Similar angles are formed by the meeting of the 
same number of corresponding similar planes. Planes which 
have like positions with respect to the axes, except as to 
direction from the center, are like planes. 

Similar planes are always like planes ; thus the faces of 
the cube are all like planes, but only the opposite faces are 
similar planes. 

Crystallographic Law Law of Axial Ratios, or Rationality 
of Parmeters or Indices. From what has preceded we see that 
symmetry is inherent in nearly all solid minerals and is part 
of their nature. Crystallographic symmetry may be con- 
sidered as a natural result of the molecular structure of a 
mineral. Certain geometric relations have been found to 
connect all the faces which belong to the crystals of any 
one mineral. 

The law governing these relations is known as the law of 
axial ratios, or the law of rationality of parameters or indices. 
It is an empirical law, but there are no known exceptions to 
it, and it is the basis of mathematical crystallography. The 
law may be stated as follows : 

The ratios of the intercepts on the same axis by the different 
planes of a crystal can only be o, oo, or rational numbers ; these 
ratios can never be irrational. The law may also be expressed 
thus : The position of all the planes of a crystal, located by their 
intercepts, can always be expressed by numbers bearing a simple 
ratio to the relative lengths of the axes of the unit form. 

The geometric consequences of this law are the exclu- 



I O CR YS TA LLOGRA PH Y. 

sion from crystalline forms of all but the simpler types of 
symmetry about an axis, binary, ternary, quaternary, and 
senary. Regular solids of a higher order than the cube or 
octahedron are thus excluded. 

Constancy of Angles. Since the planes of a crystal may 
be shifted without affecting crystallographic symmetry 
provided each plane is moved parallel to itself it follows 
that the above law, the constant ratio of the intercepts for 
the different planes of the crystal, also fixes a constant angle 
between the intersecting planes, and we may write as a 
second crystallographic law : that the angles of inclination 
between like faces of the crystals of the same species are constant. 

The unequal development of the faces of a crystal during 
its growth has the same effect as the shifting of the planes 
in directions parallel to themselves. This does not change 
the ratios existing among their intercepts ; hence the angles 
between the faces is constant, however much the faces may 
vary in size in the different crystals of the same species. 

All possible classes of crystalline forms can be deduced 
mathematically, in the same manner that possible geomet- 
rical polyhedrons are deduced, and the solution is less com- 
plex, for the law of axial ratios excludes the higher orders 
of symmetry. The possible crystalline classes are found, 
under the law, to be thirty-two. Natural representatives of 
all the possible classes are not yet known, though nearly all 
that do not occur in nature have been produced in the 
laboratory. 

Zonal Relations. The planes occurring in crystals are frequently ar- 
ranged in belts extending around the crystal in different directions. 
A zone includes a series of faces whose intersections are all parallel to 
each other. An imaginary line through the center of the crystal, par- 
allel to the common direction of intersection, is called the zonal axis. 
All the planes which belong to the same zone are said to be tautozonal. 
The zonal relation establishes the fact that the parameters of the faces 
of the same zone have constant ratios for two of the axes. 

(i) When the positions of two planes of a zone are known, the 
direction of the zonal axis is determined. The position of a plane be- 
longing to two zones is known when the directions of the zonal axes 
-are known. 



CRYSTALLINE SYSTEMS. 



II 



(2) The parameter relations between the faces of a zone make it 
always possible to deduce some simple numerical relation between the 
faces belonging to the same zone ; the relations so expressed give the 
zonal equation. The determination of what planes belong in the same 
zone is simple in principle, and not especially difficult in practice, but 
the method to be pursued cannot be here explained. 

We have seen that the symmetry of form of crystals can be ex- 
pressed in their axial relations, according to the number and character 
of their axes of symmetry. On this basis the possible groups of crystals 
are generally classed in six systems, depending upon the number, rela- 
tive lengths, and inclinations of their crystallographic axes. 



CRYSTALLINE SYSTEMS. 



I. The Isometric System. This system has three equal 
axes at right angles to each other, each axis being an axis of 
quaternary symmetry. The simplest forms under this system 
are the cube, Fig. 7, the regular octahedron, Fig. 8, and the 



---, 




FIG. 7, 



FIG. 8. 



regular dodecahedron, Fig. 9. The positions of the axes 
are indicated in the diagrams. Either of these forms can be 
assumed as fundamental and the others readily derived from 
it ; for example, if in the cube planes be passed parallel to 
one lateral axis and through the extremities of the vertical 
and the other lateral axis, the octahedron will result, or pass 
planes through the extremities of the semi-axes of the octa- 
hedron, perpendicular to one axis and parallel to the other 
two, and the intersections will form the edges of an enclosing 
cube. The faces of one or more of the above forms are 



12 



CK YS TA LLOGRA PH Y. 



sometimes found in the same crystal, as shown at Figs. 10 
and ii. 

Besides the crystallographic axes of quaternary symmetry referred 
to in this system, there are other axes of symmetry six axes of binary 




<^\ / 


I>\ 


r " N 


/ 1 

J 




FIG. 9. 



FIG. 10. 



FIG. ii. 



symmetry, which connect the middle points of diagonally opposite 
edges, and four axes of ternary or trigonal symmetry, which join the 
vertices of opposite solid angles. 

II. The Tetragonal System. In this system there are 
three axes, at right angles to each other; the two lateral 
axes are equal in length, and the vertical axis is longer or 
shorter. The simple forms in this system are the right 
square prisms, Figs. 12, and 13, and the square octahedrons, 
Figs. 14, and 15. The cross-sections of these forms, perpen- 
dicular to the vertical axes are squares. As mentioned in 
the preceding system these forms are derivable from each 
other. In this system the vertical axis is an axis of quater- 
nary or tetragonal symmetry. The lateral axes may join the 
centers of opposite faces or of opposite vertical edges. The 
relative lengths of the vertical and horizontal axes may 
vary, depending upon whether a long or short octahedron 
be assumed as the unit form. The selection of this form 
depends upon considerations already mentioned. 

III. The Hexagonal System. This system has two divi- 
sions: (a) Hexagonal, (b) Rhombohedral. (a) In the hex- 
agonal division there are four axes, one vertical and three 
lateral axes ; the lateral making angles of sixty degrees 
with each other, and the vertical axis being perpendicular 



CRYSTALLINE SYSTEMS. 



to the plane of the lateral. The vertical axis is an axis of 
senary symmetry, while the lateral axes are of binary sym- 
metry. The lateral axes are in sets of three each, the axes 
of each set being equal in length, (b) In the rhombohedral 








:^ 






- 


^ 




F 


IG. 


12 





FIG. 13. 





FIG. 14. 



FIG. 15. 



division the arrangement of certain planes around the verti- 
cal axis are alternate in the upper and lower halves of the 
crystal. This arrangement leaves the vertical axis an axis 
of ternary or trigonal symmetry instead of hexagonal, with 
three horizontal axes of binary symmetry. Some of the 
simpler forms of the hexagonal division are shown in Figs. 



CRYSTALLOGRAPHY. 



16, 17, and 18; Fig. 19 shows the possible positions of the 
lateral axes in the hexagonal division; Figs. 20 and 21 show 
two forms of the rhombohedral division. 




/K 



\s ' 






n 



FIG. 16. 



FIG. 17. 



FIG. 18. 





FIG. 19. 



FIG. 20. 



IV. The Orthorhombic System. This system has three 
rectangular axes, no two of which are of the same length. 
The simpler forms of the system are the right rectangular 
prism, Fig. 22, the right rhombic prism, Fig. 23, and the 
rhombic octahedron, Fig. 24. The planes of these three 
forms, as well as of others not mentioned, are sometimes 
found in the same crystal. 

In this system each axis is an axis of binary symmetry. 



CRYSTALLINE SYSTEMS. 



V. The Monoclinic System. This system has a vertical 
and two lateral axes, no two being of the same length. One 
lateral axis is oblique to the vertical axis, and the other 




^^ I 


^^ 


I 

L 




^\ 

u \= 





FIG. 21. 



FIG. 22. 









i 

j 




I 

i 
i 


^_J 


i 

-i 



FIG. 23. 




FIG. 24. 



lateral axis is perpendicular to the plane of the vertical and 
oblique lateral axis. The simple forms in the system are 
the rhombic prism, Fig. 25, the oblique rectangular prism, 
Fig. 26, and the right rhomboidal prism. As in the other 
systems, the planes of different forms sometimes occur hi 
the same crystal. 



CR YS TA LLOGRA PH Y. 



In different species belonging to this system the relative 
lengths and inclinations of the axes vary. 

The system has only one axis of binary symmetry. 

VI. The Triclinic System. This system has three axes of 
unequal length, each being oblique to the plane of the other 



-i .f- 

/! 

:- i 

/ 



7 



FIG. 25. 




two. A simple form is the oblique rhomboidal prism. In 
different species belonging to this system, as in the preced- 
ing, both the relative lengths and inclinations of the axes 
vary. 

There is no axis of symmetry in this system, the symmetry existing 
only with respect to a point which is a center of symmetry. In this 
case, if an imaginary plane be passed through the center parallel to one 
of the faces and the portion of the crystal on one side of the plane be 
thought of as rotated 180 about a line perpendicular to the plane and 
passing through the center, the two halves of the crystal would then be 
mirror images of each other across the plane. The center of symmetry 
of the polyhedron is also a center of symmetry for every polygonal 
figure formed by the intersection of the faces of the crystal with a plane 
passing through the center. Every such polygon rotated in the plane 
about the center occupies congruent positions after every turn of 180 
degrees. 

It will be observed that the above systems can be grouped into three 
classes, depending upon the number of their principal axes of sym- 
metry. A principal axis of symmetry has already been defined as one 
that is of the third or higher order of symmetry. This, as a general 
statement, is correct, and any crystal which has trigonal symmetry has 
a principal axis of symmetry, but an axis of trigonal symmetry is not 
necessarily a principal axis of symmetry in a system where there are 
axes of higher symmetry. Thus, in the cube (isometric), the three axes 
of tetragonal symmetry connecting the middle point of opposite faces 



CRYSTALLINE SYSTEMS. 1 7 

are principal axes, while the four axes of trigonal symmetry connecting 
diagonal opposite angles are secondary axes in this system. 

The groups of the above six systems according to the number of 
their principal axes are : 

i st. Those without a principal axis of symmetry. Under this group 
are included the Triclinic, the Monoclinic, and the Orthorhombic. The 
first is without linear symmetry, and the other two have only binary 
symmetry. 

2d. Those with one principal axis of symmetry. Under this group 
are the Hexagonal and Tetragonal ; the principal axis in the first being 
one of senary symmetry, and in the second of quaternary. 

3d. Those with three principal axes of symmetry. The Isometric is 
the only system in this group; the three principal axes of the system 
being of quaternary symmetry. 

Crystal Symmetry about Planes. In grouping the crystal forms ac- 
cording to their axial relations, only symmetry about lines and points 
has been described, but it is evident that symmetry about lines involves 
symmetry with reference to planes. The crystallographic axes assumed 
in the first four systems of crystallization result from the intersection of 
planes of symmetry. In the Monoclinic system there is one axis of 
binary symmetry, which must accordingly be perpendicular to a plane 
of binary symmetry. In the Triclinic system, there being no axis of 
symmetry, there is no plane of symmetry. Axes of symmetry are said 
to be like or equivalent when they are of the same order of symmetry 
and of the same length. Planes of symmetry are like when they divide 
the perfect form into identical halves. In general a plane which con- 
tains two or more like axes of symmetry is a principal plane of sym- 
metry, the others are secondary planes; this statement must be limited 
in the isometric system, so that the like axes shall be those of the 
highest symmetry. Principal axes of symmetry are normal to principal 
planes of symmetry, and secondary axes to secondary planes. From 
the above definition it is seen that in the isometric system the assumed 
coordinate or crystallographic axes are the principal axes formed by the 
intersections of the principal planes of symmetry. In the tetragonal 
system these coordinate axes are formed by the intersection of one 
principal plane of symmetry, with two secondary planes of symmetry, 
all at right angles to each other. 

In the Hexagonal the assumed axes are formed by the intersection of 
one principal plane with six secondary planes meeting at angles of 30. 

In the Orthorhombic system the coordinate axes are formed by the 
intersection of three secondary planes, all at right angles to each other. 
In the Monoclinic system one of the crystallographic axes is the 
normal to the plane of symmetry; the other two are in that plane and 
so chosen as to give greatest convenience : the positions of these latter 
are usually taken as previously stated. 



18 



CR YS TA LLOGRA PH Y. 



In the Triclinic system there are neither planes nor axes of sym- 
metry, and the choice of coordinate axes is arbitrary. 

Hexagonal symmetry, of necessity, includes trigonal symmetry, and 
tetragonal symmetry includes binary symmetry. 

Crystal Forms Closed and Open Forms. A form in crystallography in- 
cludes all of the like faces in the crystal like faces, as already denned, 
being those which have like positions with reference to the axes, except 





FIG. 27. 



FIG. 28. 





FIG. 29. 



FIG. 30. 



as to their direction from the origin. If all the faces of the crystal are 
like, they constitute a closed form ; that is, the enclosed solid is entirely 
bounded by like faces. If the like faces do not enclose the solid, the. 



DISTORTIONS IN CRYSTALS. ig 

form is open. There are no closed forms in the Monoclinic and Tri- 
clinic systems that is, no crystal forms in which all the faces are like ; 
in the other four systems there are closed forms, those in which the 
crystal faces are all alike. The maximum number of like faces in the 
closed forms of these systems varies with the symmetry of the system. 
The number is 48 in the Isometric, 24 in the Hexagonal, 16 in the 
Tetragonal, and 8 in the Orthorhombic, which are shown at Figs. 27, 
28, 29, and 30. The opposite pairs of the faces in these forms are simi- 
lar planes. 

Holohedral and Hemihedral Forms. When a crystal is contained by all 
the faces necessary to the complete symmetry of the system, to each 
face there is a parallel similar face, the total number being even and 
never less than six ; such forms are holohedral. There are occurring 
forms in which there are only one-half or one-fourth the number of 
faces necessary to complete symmetry; these are called respectively 
hemihedral and tetrahedral forms. 

These forms, other than the holohedral, may be considered as pro- 
duced by the suppression of one-half or three-fourths of the planes of 
the complete forms, and the extension of the remaining planes until 
they intersect. The surviving and suppressed planes in these forms are 
always those which fulfill certain definite conditions. One-half or 
three-quarters of the planes of a complete form, arbitrarily chosen for 
suppression or extension, will not produce the other forms. The sym- 
metry of the hemihedral and tetrahedral forms is of a lower order than 
that of the complete forms in the same system. The symmetrical ele- 
ments of the lower forms are less in number, but identical with the sym- 
metrical elements in the holohedral forms, and well-defined geometrical 
laws connect the forms with each other. 

DISTORTIONS IN CRYSTALS. 

It has been already stated that crystallographic symmetry is not 
always accompanied by geometric symmetry. For the purpose of de- 
scribing the systems, it is simpler to consider the ideal forms as we 
have done, but the perfect forms of the systems seldom occur in nature. 
The departures from the ideal forms which are due to the unequal 
development of the faces of the crystal and to the unequal dimensions 
of like axes are called distortions. 

Distortions render more difficult the identification of forms, but the 
constancy of interfacial angles and the identical characters of like faces 
are the means by which the difficulty is overcome. For example, the 
perfect cube is not generally met with in nature; if lengthened or 
shortened in the direction of one axis, it assumes the form of a right 
square prism ; if varied in the direction of two axes, it becomes a rect- 
angular prism (see Figs. 4 and 5). In the first case its geometric form 



20 



CR YSTALLOGRAPHY. 



would place it in the tetragonal system, in the second case in the 
orthorhombic. The physical similarity of its faces, or equal cleavage in 
the three rectangular directions, would place it in its proper system. 

Other forms more complex than the cube have distortions not so 
readily recognized, but the considerations above mentioned, together 
with a general familiarity with the more common distortions, usually 
serve to place the specimen under consideration. The faces of crystals 
are frequently not plane surfaces: they may be either striated or curved, 
These imperfections in crystals may result from oscillatory combinations 
or twinning, to which reference will be made. Curvature is also some- 
times due to mechanical causes, as is thought to be the case in tourma- 
line, or to the molecular conditions of crystallization, as in the diamond. 



MULTIPLE CRYSTALS. 

The crystal individuals thus far considered have all been polyhe- 
drons, whose interfacial angles are less than 180. Such is always the 
case with the distinct individual. On many crystalline surfaces re- 
entering angles are found which always indicate a combination of two 
or more individuals. These groups of crystals conform to certain defi- 
nite laws. A few of the important groups will be briefly referred to. 

Parallel Grouping. The simplest cases of parallel grouping consist 
of similar crystals so arranged that the line joining their centers coin- 
cides with a crystallographic axis or is parallel to it. These forms are 
illustrated in Figs. 31, 32, 33. If two cubes were joined as are the forms 
in Fig. 31, there would result a right square prism which would appear 






FIG. 31. 



FIG. 32. 



FIG. 33- 



as a single crystal. The re-entering angles denote the junction of sepa- 
rate individuals in parallel growth. 

If the width of the alternating planes is very small, there results what 



* 



MULTIPLE CRYSTALS. 21 

appears to be a single crystal with striated faces ; this arrangement of 
planes in a surface is termed oscillatory combination ; there is an ap- 
proximation to this in Fig. 33. 

Often complex crystalline forms result from parallel growths. Many 
of the delicate dendritic forms are thus brought about. In these par- 
allel groupings the crystal as a whole is symmetrical with reference to 
some plane which is also a plane of symmetry for each individual form. 

Twin Crystals. In twinning combinations two individual crystals or 
two halves of the same crystal are joined so as to have either a common 
crystallographic direction or crystallographic plane, but the parts are 
not in completely parallel positions. The two crystals or two halves of 
the same crystal are accordingly symmetrical with reference to a plane 
which is not a plane of symmetry for the individuals, and this is the 
main distinction between the parallel grouping and the twinning posi- 
tion. 

The relation of the parts in a twin crystal may be understood from 
Fig. 34, which shows a regular octahedron divided into halves by a plane 
parallel to an octahedral face ; in the figure the front half has been 
rotated through 180 about an axis normal to the plane. 

Contact Twins. The form of structure shown in Fig. 34 is an exam- 
ple of what is designated as contact twins ; this particular form is also 
termed a hemitrope crystal. Another form of contact-twinning is- 
shown at Fig. 35. 

Penetration Twins are those in which the twinning crystals are not 
joined along a plane, but more or less completely penetrate each other. 
Such forms are shown at Figs. 36, 37, and 38. 

Repeated Twinning. A third individual may be added to one of the 
two crystals of a twin according to the same law that joins the first two, 
thus causing repeated twinnings, giving rise to trillings, fourlings, five- 
lings, etc. The variations of form resulting from the different applica- 
tions of the twinning laws are very numerous, and further reference to 
them cannot be here undertaken. 

Pseudomorphs. Minerals generally belonging to one crystalline sys- 
tem are sometimes found to have the form of another. Such crystals 
are called pseudomorphs. They are thought to result sometimes 
through a change of composition in the mineral, or else the pseu- 
domorph is formed by the filling of a cavity left by the removal of a 
crystal of another form. 

ISOMORPHISM. 

Some of the compounds of certain elements crystallize 
in the same form ; and not only this, but one of these ele- 
ments may replace the others in a crystal without destroying 



22 



CR YS TA LLOGRA PH Y. 





FIG. 34. 



FIG. 35. 




FIG. 36. 





FIG. 37- 



FIG. 38. 



CRYSTALLINE AGGREGATES. 2$ 

the form ; such elements are said to be isomorphous. Cal- 
cium, magnesium, and iron are notable examples. 



CRYSTALLINE AGGREGATES. 

Most mineral masses are not composed of distinct crystal 
forms, but consist of an aggregation of imperfect crystals. 
Sometimes the aggregation is wholly irregular, and some- 
times more or less regular. There are many varieties of 
aggregates. The planes between the individuals in aggre- 
gates are simply planes of fracture ; when the fracture gives 
rise to a coarse rough surface it is called hackly ; when it 
gives rise to a smooth flat surface it is called even; and when 
it gives rise to curved surfaces, having shell-like appear- 
ances, it is called conchoidal. Some of the more important 
and common aggregates are : 

1. Dendritic. Composed of small crystals arranged in 
such a manner as to give a tree-like appearance, as in native 
gold and silver. The term is also frequently used for simi- 
lar forms, whether due to crystals or not, as to those pro- 
duced by the oxide of manganese 

2. Drusy. Composed of many small crystals implanted in 
a finer ground-mass, giving a very rough surface. 

3. Columnar or Fibrous. Composed of columnar or 
fibrous individuals, sometimes aggregated so as to give the 
appearance of a heterogeneous mixture, sometimes forming 
star-like groups, and sometimes giving rise to globular 
forms. These globules are sometimes arranged so as to 
give rise to forms resembling bunches of grapes, and there- 
fore called botryoidal. If the globular masses be nearly 
hemispheres, the form is called mammillary. 

4. Lamellar. Consists of plates or leaves. If the plates 
are very thin and easily separable, the structure is foliated, 
especially if the plates are minute scales. The varieties of 
mica well illustrate this structure. 

5. Granular. Composed of grains, either coarse or fine ; 
sometimes so fine that they cannot be detected by the 
microscope, then said to be cryptocrystalline ; sometimes of 



24 CRYSTALLOGRAPHY. 

the size of peas, giving rise to pisolitic forms ; sometimes of 
the size of the roe of fish, giving rise to oolitic forms ; some- 
times flattened like lenses, giving rise to lenticular forms. 

6. Concretions. Vary in shape from simple spherical 
masses to very grotesque aggregations, but always rounded 
in form. The more perfect forms often consist of concentric 
layers. The individual grains present in the granular for- 
mations are often concretions, as in the oolitic. One form of 
concretion, intersected by cracks which have been filled by 
foreign matter, is called a septarium or turtle-stone. 

7. Stalactitic. Cylindrical or conical in shape, composed 
of fine grains, fibers, or lamellae deposited from solution. 

7. Stratified. Composed of layers, sometimes of the same 
color throughout, sometimes of different colors, giving 
rise to banded forms; the layers are formed by successive 
deposition. 

8. Geodes. Forms resulting from incomplete filling of a 
cavity by a mineral, the interior often being covered witk 
crystals. 



*/t 



CHAPTER II. 

PHYSICAL AND CHEMICAL PROPERTIES OF MINERALS, 
PHYSICAL PROPERTIES OF MINERALS. 

THE properties of minerals which are useful in deter- 
minative mineralogy are of two kinds, viz., physical and 
chemical. The more important physical properties and 
those which can be most readily observed are (i) luster, (2) 
color, (3) hardness, (4) streak, (5) malleability, (6) taste, odor, 
and feel, (7) specific gravity. 

Luster. There are two general classes of luster, (i) 
metallic, (2) unmetallic. Metallic luster includes semi-metal- 
lic ; the name of the luster indicates the nature in each case. 
Unmetallic luster includes (i) vitreous, (2) resinous, (3) 
pearly, (4) greasy ; again, the name indicates the character 
in each case. 

Color. The mineral kingdom displays a great variety of 
colors. Colors are generally important only in the case of 
pure specimens. Some of the more common mineral colors 
are red, yellow, white, gray, brown, and black. A mineral 
is said to be opalescent when a milky, pearly, or glistening 
reflection is obtained from it ; phosphorescent when it emits 
light by friction or by being heated ; iridescent when it gives 
rainbow colors from the interior. When a mineral reflects 
prismatic colors upon being turned in the light it is said to 
give a play of colors. 

Streak. This is the name given to the color of the pow- 
der obtained by abrading the mineral, or to the color of the 
streak obtained by drawing it across a small plate of 
white porcelain. 

25 



26 PHYSICAL AXD CHEMICAL PROPERTIES OF MINERALS. 

Hardness. The hardness of minerals is determined by the 
use of a file. Care must be exercised in selecting a portion 
of the specimen to be rubbed with the file, as the true hard- 
ness will not be obtained upon very acute angles, or upon 
parts altered by exposure. The sound emitted as the file is 
drawn across the specimen is often as good a guide as the 
ease with which the specimen is abraded. For purpose of 
comparison, the following scale of hardness is adopted: 
i, talc ; 2, rock salt ; 3, calcite ; 4, fluorite ; 5, apatite ; 6, ortho- 
clase ; 7, quartz ; 8, topaz ; 9, sapphire ; 10, diamond. 

Malleability. When portions of a mineral can be flat- 
tened under the hammer it is said to malleable. 

Brittleness. When a mineral crumbles under the applica- 
tion of a force it is said to be brittle. 

Flexibility. When a mineral, or part of it, will bend and 
remain bent upon the relief of the force it is said to be 
flexible ; when it will return to the original position upon 
the relief of the force it is said to be elastic. 

Sectility. Refers to the property possessed by some 
minerals of being cut into thin slices without crumbling, but 
which crumble under the hammer. 

Odor. Odors are developed by moisture, heat, or acids ; 
only a few common ones need description : 

Argillaceous Odor. That of moist clay, developed when a 
clayey mineral is breathed upon. 

Alliaceous Odor. That of garlic, developed when the 
arsenical minerals are heated by friction or by the blow- 
pipe. 

Sulphurous Odor. That of burning sulphur, developed by 
heating some of the sulphides in air, or by burning sulphur. 

Feel. Some minerals have characteristic greasy, rough, 
or smooth feel. 

Specific Gravity. The specific gravity of a substance is 
the ratio of the weight of a given volume of the substance 
to the weight of an equal volume of water at a standard 
temperature. One of the simplest ways to determine 
specific gravity is to obtain the weight of a small piece of 
the mineral, and then to obtain the weight of this same 



CHEMICAL PROPERTIES OF MINERALS. 2/ 

piece immersed in water. These observations are sufficient 
to determine the specific gravity for ordinary purposes. 
There are specially contrived balances for taking these 
weights. 

For porous minerals the specific gravity is obtained by 
the use of a bottle of standard capacity by weight. A 
known weight of water is poured from the bottle and then 
the powdered mineral is added until the volume of the 
water is the same as before. From the original weight of 
water, from the weight of the water removed, and from the 
weight of the water with the mineral added the specific 
gravity can be obtained. 

This method is of course equally applicable to compact 
minerals. 

For minerals soluble in water a liquid must be used 
which will not dissolve them and whose specific gravity is 
known. 

The physical properties are of great importance in deter- 
minative mineralogy and many common species can be 
approximately determined by them. 

Tables to assist in the determination of the minerals 
described are included in the text. These tables have been 
prepared by classifying the minerals according to luster, 
subclassifying under luster according to color, color of 
streak, or hardness. Other physical properties are tabu- 
lated, and a column of remarks noting characteristics, not 
elsewhere included, is added. 

/'. / 

CHEMICAL PROPERTIES OF MINERALS. 

/ ,/ tnr 

If a specimen cannot be fully determined by the physical 
tests, the chemical properties must be considered. While 
the chemical tests will often afford a ready means for 
determining a specimen, it is always better to consider 
physical characters first. 

For examining the chemical properties of minerals the 
following facilities are usually to be had in the laboratory : 
hammer, anvil, steel mortar, agate mortar, forceps, open and 



28 PHYSICAL AND CHEMICAL PROPERTIES OF MINERALS* 

and closed tubes, charcoal, blowpipe, platinum wire, fluxes, 
and reagents. 

Hammer and Anvil. These are for removing small pieces 
from the specimen for subsequent treatment. By holding 
the specimen on the anvil a sharp blow properly adminis- 
tered will usually separate a suitable fragment. 

Steel Mortar. This is used for powdering the fragment, 
and the mortar should always be placed on the anvil for 
use. The agate mortar and pestle are used for further pul- 
verization by friction of the power obtained from the steel 
mortar. 

Forceps. Any forceps provided with platinum tips will 
answer ; but those so made that the tips will press together 
of themselves will be found most convenient. The forceps 
are used in connection with the blowpipe for fusing, or for 
detecting a volatile ingredient, which may yield an odor or 
color the flame. Only a small thin sliver of the specimen 
should be used, and it should be held so as to project well 
beyond the point of the forceps. Minerals easily reduced to 
the elementary state should not be heated in contact with 
the forceps, and as a rule it is well not to use the forceps 
with those having metallic luster. 

Charcoal. Charcoal is used as a support upon which 
various bodies are heated. The heating may be for the 
purpose of fusing, for volatilizing, or for the production of 
a sublimate. The odor from the volatilized body and the 
color of the sublimate, near and at a distance from the 
assay, are often characteristic. An infusible and non-volatile 
residue can often be subjected to additional treatment. 

Besides serving as a support as above indicated, the 
reducing power of the charcoal is often made use of to 
deoxidize certain bodies, as metallic oxides. The production 
of sublimates is often facilitated by the use of fluxes. Easily 
reducible compounds, as those of lead, zinc, arsenic, and 
antimony, should always be heated on charcoal and not in 
the forceps. 

Open Tubes. These are used to heat the mineral in con- 
tact with air. A small fragment, or better some of the 



CHEMICAL PROPERTIES OF MINERALS. 2$ 

powdered mineral, is put in the tube and the tube heated, 
being held as highly inclined as possible; the result to be 
expected will of course depend upon the particular mineral, 
and the observations to be noted are indicated in the tabular 
description of the species. 

Closed Tubes. These are used for heating the mineral 
out of contact with air and for making tests with liquid 
reagents. Only a very small quantity of the mineral must 
be used except in cases particularly specified, and only a 
small quantity of acid is necessary. Attention is called to 
the phenomena to be observed, in the tables above re- 
ferred to. 

Blowpipe. The blowpipe is simply a bent tube, with a 
very narrow orifice, provided with a platinum tip which can 
be removed and cleaned. Only very small pieces or amounts 
of mineral must be used before the blowpipe. 

In using the blowpipe it is necessary to blow and breathe 
at the same time, for results can generally be accomplished 
only by continued application of the flame for some time. 
This accomplishment is readily acquired by practice. Care 
must be taken that the flame be well protected from draft 
or anything which would cause flickering. The flame 
should be colorless, for the characteristic colors of many 
minerals are readily developed before the blowpipe. 

Platinum Wire. This is used for facilitating the action 
of the fluxes on the minerals and for affording opportunity 
for observing the action ; such action frequently gives 
characteristic colors. In general the manner of using the 
wire is as follows : Twist it into a small loop at the end, heat 
it, and dip it into the flux, and fuse to a clear bead, then 
into the powdered mineral, and fuse again ; repeat the opera- 
tion and observe carefully the fused mass, which is called 
a bead. The blowpipe may or may not be used in heating 
the beads; in some cases the beads have one color in 
the oxidizing flame and another in the reducing flame, as 
described in the tables. 

Fluxes. The common fluxes for making beads are borax, 
sodium borate, salt of phosphorus, phosphate of sodium and 



30 PHYSICAL AND CHEMICAL PROPERTIES OF MINERALS. 

ammonium, and soda, sodium carbonate. They owe their 
value to the fact that they dissolve or combine with metallic 
oxides, giving characteristic colors ; the mineral should be 
roasted before making a bead, so that the oxide will be 
formed if it is not already present. 

Soda is a very valuable flux for decomposing the 
metallic compounds. 

Reagents. The more common and useful reagents are 
sulphuric, hydrochloric, and nitric acids, ammonia, am- 
monium sulphide, potassium ferrocyanide, and ammonium, 
oxalate. 



SOME IMPORTANT AND COMMON MINERAL TESTS. 

(These should be learned at once by the student.) 

Before the Blowpipe Copper. Copperminerals moistened 
with hydrochloric acid give the flame an azure-blue color ; 
heated alone the flame is colored green. 

Iron. Minerals containing iron are converted into mag- 
netic oxide in the reducing flame; sometimes soda is re- 
quired. 

Lead. Lead minerals heated on charcoal with soda give 
a yellow oxide coating on charcoal and leave a lead globule. 

Zinc. Important zinc ores when heated on charcoal 
give a coating of oxide, yellow while hot, but white on 

cooling. 

Open-tube Tests. Arsenic. The common arsenical com- 
pounds give a white sublimate of arsenious oxide on the 
tube, an alliaceous odor, and an acid reaction with litmus 
paper. 

Sulphur. Sulphides give an odor of sulphurous oxide 
and an acid reaction. 

Closed-tube Tests. Arsenic. The common arsenic com- 
pounds in a closed tube give a coating of arsenic, a coating 
of red and yellow orpiments if sulphur be present, and emit 
an alliaceous odor. 

Carbon. Carbon mixed with a nitrate and heated will 
deflagrate. 



MISCELLANEOUS TESTS. 3 1 

Copper. To test for copper treat with nitric acid and add 
excess of ammonia ; if copper be present, a blue solution is 
given ; copper sulphides must first be well roasted. 

Calcium. To test for calcium treat with hydrochloric 
acid, neutralize with ammonia, add a soluble oxalate, and 
calcium oxalate will fall. 

Iron. To test for iron treat with hydrochloric acid, add 
potassium-ferrocyanide, and a blue precipitate will be 
formed. 

Mercury. To test for mercury mix a salt-spoonful with 
twice its volume of soda, heat, and globules of mercury will 
be deposited on the cool sides of the tube. 

Water. To test for water put the powdered mineral in 
the tube, heat the latter held in a nearly horizonal position ;, 
if present, water will be deposited on the cool sides of the 
tube. 

MISCELLANEOUS TESTS. 

Carbonates. Treated with hydrochloric, nitric, or sul- 
phuric acid, carbonic acid gas escapes with effervescence ; 
decomposition will sometimes take place if a drop is put on 
the mineral in mass; but in some cases the mineral must be 
pulverized ; in others the application of heat is necessary. 

Sulphates. With few exceptions, heated with hydro- 
chloric or nitric acid treated with a soluble salt of barium, 
yield a white precipitate of barium sulphate. 

Nitrates: Heated on charcoal deflagration takes place; 
or better, heated in a tube with powdered charcoal deflagra- 
tion occurs. 

Sulphides. Heated with soda on charcoal, moistening 
assay so obtained and placing on a silver plate, the latter will 
be tarnished if sulphur be present. The sulphides heated 
with nitric acid often give a mass of sulphur floating on the 
surface of the acid ; sulphides roasted in air give a sulphur- 
ous odor. 



CHAPTER III. 

DESCRIPTIVE MINERALOGY. 

NATIVE ELEMENTS. 

Diamond, C. 

Isometric. Commonly in octahedrons, but often in more 
complex forms, faces frequently curved. 

The diamond varies from colorless specimens through 
various shades of yellow, orange, red, green, blue, brown, 
and sometimes black. Transparent when white, dark 
varieties translucent to opaque. The luster is adamantine to 
greasy. H. = 10. G. = 3.516-3.525 in distinct crystals. 

Bort is a rounded variety of diamond, with rough exterior 
and lacking distinct crystalline structure ; its hardness is 
greater than the ordinary form (distinct crystals), but its 
specific gravity less. 

Carbonado, or black diamond, is massive, but with crys- 
talline structure, sometimes granular to compact ; its specific 
gravity is sometimes as low as 3.01, but it excels in hardness 
all other forms. It is found mainly in Brazil. 

The composition of the diamond is essentially pure 
carbon, but the different specimens of the gem which have 
been tested by combustion leave a small quantity of ash, 
showing impurity varying from one-twentieth of one per 
cent to two per cent. In this ash, silica and the oxide of 
iron have been detected. The black diamond leaves the 
greatest amount of ash. 

The diamond heated to a very high temperature with 
the air excluded is converted into a black mass resembling 
graphite or coke, without loss of weight ; highly heated in 
the air it is completely oxidized (except the small quantity 
of ash) yielding CO,. 

32 



UNI V ft ASH' V OF 

Mf*TMKMT or CIVIL CNQI M cam 

KRKCLKY, CALIFORNIA 

NATIVE ELEMENTS. 33 

The diamond, until the discovery of the South African 
fields, was found mainly in alluvial deposits of gravel, sand, 
and clay, often associated with gold, platinum, quartz, topaz, 
garnets, corundum, tourmaline, and other accessory miner- 
als. The frequent presence of itacolumite in the diamond 
regions, and the fact that diamonds have been found in this 
rock in Brazil, have led to a rather general belief that ita- 
columite (flexible sandstone) is the principal original 
diamond-bearing rock. The occurrence of diamonds in 
place in the South African mines shows that such is not the 
case. In these fields the diamonds are found associated and 
imbedded in a highly basic, brecciated volcanic rock, and it 
is still undetermined whether the diamonds were present in 
the original rock from which the breccia came .or whether 
they were produced by the action of the volcanic products 
upon the carbonaceous material which is found in the region 
as shale. Prof. H. C. Lewis, who gave able consideration 
to the subject, advocated the latter theory. 

The South African mines have yielded more diamonds 
than all the previous production of the world. Ninety-five 
per cent of the world's yearly supply of diamonds is now 
obtained from these mines, the remainder coming almost 
entirely from Brazil, India, and Borneo. A few diamonds 
have been found in the United States and Australia ; those 
obtained in this country have been found mainly in the 
Southern Alleghanies from Virginia to Georgia, or in the 
Sierra Nevada or Cascade ranges in Northern California 
and Oregon. 

Graphite, Plumbago, Black Lead. 

Hexagonal In six-sided laminge, commonly imbedded in 
foliated masses. Granular to compact and earthy. 

Graphite is carbon with from one to five per cent ot 
mechanical impurities, generally oxides of iron, manganese, 
and silicon. It varies in color from iron-black to steel-gray ; 
streak black, shining; luster metallic. H.= i to 2. G. 2.2^. 
Makes dark streak on paper and has greasy feel. It is infu- 



34 DESCRIPTIVE MINERALOGY. 

sible both alone and with reagents and is not acted upon by 
acids. Combustible only at very high temperature. Defla- 
grates when thoroughly mixed with niter and heated in a 
closed tube. In appearance greatly resembles molybdenite 
(MoS), but this gives off sulphurous fumes before the blow- 
pipe and is acted upon by nitric acid. 

Graphite occurs as scales and grains, nodular masses,, 
and in beds, generally in the crystalline rocks. It is found 
in New York, Pennsylvania, Massachusetts, Connecticut,, 
Rhode Island, New Jersey, North Carolina, South Carolina, 
Colorado, and California, and in several other states. It has, 
been mined in New York, Massachusetts, Connecticut* 
California, and North Carolina. The Ticonderoga mine in. 
New York and the Herron mine in North Carolina are the 
most important. 

Ceylon, Bavaria, and Siberia supply most of the foreign- 
graphite and much that is used in this country also. The 
English deposit at Borrowdale long furnished a superior 
quality of graphite, but is now nearly worked out. 

Graphite is largely used for the manufacture of lead- 
pencils, being ground up, and generally mixed with some 
cementing material and solidified by pressure. Fine clay is. 
used in the harder pencils. It is also largely used as a lubri- 
cant for machinery, for coating objects to be electrotyped, 
for polishing stoves and other iron- work, as a paint for 
smokestacks, boilers, etc., and for making crucibles ; for the- 
latter purpose being mixed with clay. 

Native Sulphur, St 

Orthorhombic. Most common form, right rhombic acute 
octahedron. Also various modifications of this form, and 
massive. 

Sulphur when pure is of a clear yellow color, frequently 
somewhat translucent, but sometimes opaque. Its streak is. 
yellow, sometimes tinged reddish or greenish ; it is very 
fragile and breaks with conchoidal fracture, vitreous or- 
resinous luster. G. = 2.1. H. = 1.5 to 2.5. Readily combusr- 



NATIVE ELEMENTS. 35 

tible, burning with blue flame and producing suffocating, 
acrid fumes. In closed tube wholly volatilizes and deposits 
on cool part of tube. 

The native form is most generally met with as masses or 
small grains disseminated in other minerals, or as fine yellow 
powder lining cavities. It often contains clay or bitumen 
and is sometimes colored orange-yellow by selenium sul- 
phide. The largest deposits of sulphur are found in recent 
sedimentary strata associated with gypsum or allied rocks, 
or in regions of extinct or active volcanoes ; nearly all active 
volcanic regions yield it in some abundance. The greater 
proportion of the supply of native sulphur is obtained from 
the volcanic districts of Sicily. It is usually purified from 
earthy impurities by fusion before shipment to the world's 
market. 

Sulphur deposits are found in many places in the United 
States both in the East and the West. Those in the Eastern 
States are too small to be of industrial importance except cer- 
tain beds in Louisiana, which are, in places, over one hundred 
feet thick and contain a large quantity of pure sulphur, but 
they are four or five hundred feet below the surface. The 
difficulty of mining these deposits has thus far proven so 
great that they have yielded only a small quantity of sul- 
phur. Deposits in the West are numerous and occur in Cali- 
fornia, Nevada, Utah, Wyoming, New Mexico, and Arizona 
Those most important as a source of sulphur are at the Rab- 
bit Hole mines, in Humbolt County, N. W. Nevada. These 
at the present time furnish the greater proportion of the 
sulphur mined in the United States. The mines near 
Beaver, Utah, are next most productive. Sulphur is very 
generally deposited around springs whose waters contain 
hydrogen sulphide in solution, especially in volcanic regions. 
Immense deposits of sulphur are known to exist in the crater 
of Popocatepetl. The sulphur consumed in the United 
States comes mainly from Sicily, which also furnishes the. 
greater proportion of the world's supply. 



36 DESCRIPTIVE MINERALOGY. 

Native Gold. 

Isometric. Octahedrons and dodecahedrons, but these 
are rarely found. 

Gold has a yellow color in mass, but when reduced to 
very fine powder it is ruby-red. It is very ductile and mal- 
leable. H. = 2.5 to 3, nearly as soft as lead. G. = 19 to 19.3. 
Fusing-point slightly above 2000 F. Not acted upon by 
any of the common acids ; dissolved by nitro-muriatic acid ; 
does not oxidize in the air. 

Gold is seldom found pure. It is most commonly alloyed 
'with silver, sometimes with copper, iron, rhodium, and bis- 
muth. It is occasionally found combined with tellurium. 
The silver present in the gold varies from a fraction of a 
per cent to one-third of the whole. An amalgam of gold 
and mercury has been found in Colombia, S. A., and in Col- 
orado. The native gold of California averages about 88 per 
cent of gold, the remainder being mostly silver. The native 
alloys with silver are much lighter in color than gold and 
occasionally nearly silver-white. 

Iron and copper pyrites may closely resemble gold in 
color and have, by the inexperienced, been mistaken for it ; 
for this reason they are sometimes called "fools gold." 
These minerals are brittle and give off sulphurous fumes 
when roasted in the air, which at once distinguish them from 
gold. 

Gold occurs principally in two ways: i. In quartz veins 
intersecting metamorphic rocks, frequently associated with 
ores of other metals. 2. As grains and nodules in the gravel 
and sands of the rivers and valleys of auriferous regions. 
The deposits in the second case result from degradation of 
the veins. The quartz veins most commonly occur inter- 
secting metamorphic talcose, chloritic and argillaceous 
schists, less frequently in diorites and porphyries. 

The gold occurs irregularly distributed throughout the 
quartz of the vein, in strings, scales, and grains, and is often 
invisible to the naked eye. The most perfect crystals and 
largest masses generally occur in the cavities of the quartz. 



NATIVE ELEMENTS. 37 

The most common minerals accompanying the gold in the 
vein-stuff are the sulphides of iron, copper, lead, and zinc 
and the red oxide of iron. The iron pyrite exceeds in quan- 
tity all the other minerals and is usually auriferous, the 
others frequently so. 

The quartz of the veins, for some distance below the sur- 
face, is often cellular and porous owing to the alteration and 
removal of the associated minerals by atmospheric agencies. 
The gold that was present in the removed mineral is thus 
frequently left in strings or scales in the cavities of the 
quartz. This weathered portion of the vein is more easily 
mined and the gold more easily obtained from it than from 
the unchanged portion. In quartz mining the gold is either 
obtained from the quartz or from the associated minerals ; 
the pyrite of a gold region is often worked as a gold ore, as 
is also the galenite. 

The method of obtaining the gold from the sands and 
gravels constitutes "alluvial washing"; in California called 
placer mining. The origin of these deposits is given in 
Geology. The gold is obtained from the deposits by taking 
advantage of its great specific gravity, the earthy matter 
being washed away by water. At first this was accom- 
plished by simple pan or cradle washing, but soon in Cali- 
fornia it developed into hydraulic mining upon a stupendous 
scale ; water for this purpose being often brought from long 
distances by artificial channels and turned, under great 
pressure, on the gravel-beds. Large bodies of sand could 
by this means be washed over; only by such means 
would it have been possible profitably to work immense 
beds of comparatively ppor material. The most imposing 
beds of sand and gravel disintegrate and melt away under 
the enormous force, aided by the softening power of the 
water. 

The cost of handling a cubic yard of auriferous gravel 
by the best method of washing employed in 1852 was re- 
duced more than fifty times by the introduction of the 
California hydraulic process, and as compared with the 
simple pan-process the cost was reduced a thousand times. 



38 DESCRIPTIVE MINERALOGY. 

i 

The auriferous beds thus washed over were often from 
one to two hundred feet thick. Up to the present time 
the greater portion of the world's supply of gold has come 
from the alluvial washing and not from the quartz minings. 

Gold is very widely distributed over the globe, being 
found to some extent in nearly all countries. It occurs in 
crystalline or semi-crystalline rocks of various ages from 
the tertiary downward. 

Up to the year 1890 the United States, Australia, and 
Russia produced by far the greater proportion of the 
world's supply of gold ; since that year the gold-fields of 
Africa have added largely to the production. In 1897 rich 
discoveries were reported on the uper waters of the Yukon, 
but the importance of the Klondike deposit is not yet fully 
determined. 

Gold is mined in many of the States of the United States 
and also in Alaska. Since 1849, the nrs ^ year after the dis- 
covery of gold in California, that State has almost contin- 
ually led in the production of gold. The California pro- 
duction rose from five millions in 1849 to sixty millions in 
1853. In that year the maximum was reached. Between 
1872 and 1878 Nevada produced more gold than California, 
as did Colorado in 1897 and 1898. At the present time 
California, Colorada, South Dakota, Montana, Nevada, 
Arizona, Alaska, Idaho, Oregon, and Utah are our principal 
producing regions, though many other States are small pro- 
ducers. 

The localities of gold-mines in the United States are too 
numerous to mention in full, but they are spotted from Ala- 
bama to Labrador along the Appalachians and are numerous 
in the Rocky Mountains and along the western slope of the 
Sierras ; the eastern slopes of the Sierras generally produce 
silver. 

Native Platinum. 

Isometric. Native crystals rare, cubes most common ; 
usually in grains, scales, and small masses. 



NATIVE ELEMENTS. 39 

Pure platinum is nearly silver-white, but the native metal 
nearly steel-gray ; streak same ; metallic, shining luster ; duc- 
tile and malleable. H. =4 to 4.5. G. = i6to 19; when pure, 
about 21. It is the most difficult metal to fuse, and is not 
acted upon by the common mineral acids. Native platinum 
is usually alloyed with one or more of the metals osmium, 
rhodium, iridium, palladium, copper, and iron. 

Russia supplies much the larger portion of the platinum 
of commerce. It is found mainly in alluvial material in the 
Ural Mountains, near Goroblagodat. Brazil, Borneo, Co- 
lumbia, and St. Domingo supply a small amount. It has also 
been found in the United States at several places, in Canada, 
and in Australia. Its great use is for the construction of 
chemical and philosophical apparatus. 

Native Silver. 

Isometric. In octahedrons without apparent cleavage, 
often aggregated into mossy, arborescent, or filiform shapes ; 
occasionally into solid masses. 

Silver is white, often tarnished black by sulphur. 
Malleable and ductile ; streak white and shining. H. = 2.5. 
G. = 10.1 to H. Fuses at about 1900 F. It is dissolved by 
nitric acid, and the solution gives a white precipitate by the 
addition of any soluble chloride. The precipitate blackens 
in the light and dissolves in solution of ammonia. 

Native silver is frequently alloyed with copper, and 
sometimes with bismuth. It is readily distinguished from 
tin, bismuth, and other white metals by its high fusing and 
volatilizing points, its great malleability, and by the wet test 
above given. 

Native silver occurs in veins traversing metamorphic 
rocks. It is usually accompanied by the ores of silver, and 
frequently of other metals. Four-fifths of the product from 
the celebrated mine of Kongsberg, Norway, was native 
silver. This mine was discovered in 1623, and several 
masses of silver weighing from 100 to 500 pounds have been 
taken from it. 



40 DESCRIPTIVE MINERALOGY. 

Silver is found in the Lake Superior region penetrating 
the native copper. It there exists in strings and masses, 
and is nearly pure silver. It has also been found in similar 
forms in the silver-mines of Idaho, Colorado, California, and 
Nevada. Peru has furnished much native silver, and much 
has come from Northern Mexico. Both gold and silver are 
present in sea-water, though to a very small extent. 



ORES OF SILVER. 

Argentite, Silver Glance, Ag 3 S. 

Isometric. This important ore of silver generally occurs, 
when crystalline, in some modification of the dodecahedron, 
also in dendritic, capillary, and reticulated forms, massive. 

Argentite has a dull metallic luster ; its color on fresh sur- 
face is a blackish lead-gray, streak similar to color, and 
glistening. It is malleable and sectile. H. = 2 to 2.5. 
G. = 7.2 to 7.4. Fuses before the blowpipe and gives off 
fumes of burning sulphur, yielding a bead of silver. Acted 
upon by nitric acid with a separation of sulphur ; hydro- 
chloric acid added to nitric acid solution gives precipitate 
of silver chloride. Solution in NO 3 H deposits silver on 
copper plate. Silver sulphide is distinguished from the re- 
sembling ores of lead and copper by its malleability, by 
yielding silver on charcoal ; it is also heavier, than resembling 
copper ores. 



Pyrargyrite, Ruby Silver, Dark Red Silver Ore, Ag 3 SbS 3 . 

Rhombohedral. Occurs in columnar crystals, faces often 
rounded, also massive. 

This ore in thin fragments has a dark cochineal color, in 
larger masses nearly black, streak cochineal or brownish 
red ; fuses easily before the blowpipe with spirting, giving 
white coating of antimony oxide, ultimately a bead of sil- 
ver. In open tube gives sulphurous fumes and white 



ORES OF SILVER. 4* 

sublimate, in closed tube red sublimate. Decomposed by 
NO 3 H, depositing sulphur and the sesquioxide of antimony. 



Proustite, or Light Red Silver Ore. 

This ore is closely related to pyrargyrite, but contains 
arsenic, replacing the antimony in part or whole. The streak 
and color are brighter red than in pyrargyrite. Heated in 
air gives sulphurous and arsenical fumes, in open tube white 
sublimate, in closed tube yellow orpiment. 



Stephanite, Black Silver, Brittle Silver Ore. 

This ore is also a sulphide of silver and antimony, whose 
composition is represented by the formula Ag B SbS 4 = 
5Ag. 2 S,Sb 3 S 3 . It has metallic luster. 

Black color and streak; is brittle and usually massive. In 
the open tube fuses, giving off sulphurous and antimonial 
fumes ; before the blowpipe on charcoal fuses easily, giving 
a coating of antimony oxide, with soda a globule of silver. 

Cerargyrite, Horn Silver, AgCl. 

Isometric. Usually occurs massive or as incrustations, 
also in cubes without cleavage, rarely columnar ; color pearl- 
gray to greenish gray and occasionally violet-blue ; by ex- 
posure to light color changes to purplish brown, nearly 
black. When pure sometimes colorless. Luster waxy, res- 
inous to adamantine; in many cases cuts and looks like horn. 
H. = i to 1.5. G. = 5.5. Fuses in closed tube without de- 
composition, on charcoal reduced to metallic silver. Soluble 
in ammonia. 

This is a common ore and has been extensively worked 
in our Western mines and in Mexico. 

The native metal furnishes only a small part of the 
world's supply of silver, the larger portion coming from the 
other ores of silver, the principal of which are the silver 



42 DESCRIPTIVE MINERALOGY. 

sulphide, the sulpharsenides, sulph-antimonides, the chlo- 
rides and bromides and the mixtures of these with the oxides, 
sulphides, arseniates, and carbonates of other metals. The 
principal ores of the Comstock Lode were native silver and 
gold, argentite (silver sulphide), and stephanite (sulphide of 
silver and antimony). Two hundred and eighty millions in 
silver and gold were taken from this lode between 1860 and 
1880. In the celebrated Ruby Hill mine at Eureka, Nev., 
the silver occurred mainly as argentite and chloride mixed 
with limonite, lead sulphite and sulphate and carbonate, and 
several other minerals. The most important ore of the 
Leadville region is auriferous galena with lead carbonate 
and silver chloride. Native gold and silver occur in the 
ores at both the places last named. 

The United States, Mexico, and South America have, up 
to the present time, furnished the greater portion of the 
world's silver. For the past dozen years the United States 
has furnished considerably over one-third of the world's 
product of silver. During this time the silver yield of this 
country has varied in value from about 40 to 76 millions of 
dollars. Nevada, Colorado, Montana, Utah, the Dakotas, 
and Idaho have been the principal contributors. 



Cinnabar, HgS. 

Cinnabar generally occurs massive with slightly granular 
texture ; when pure, it has a bright red to brownish-red color; 
streak scarlet; luster adamantine. H. = 2 to 2.5. G. = 9 ; 
less when impure. Impure varieties often have slaty struc- 
ture with darker color; streak tending to brown. Other 
impure varieties are of a yellowish-red color, little luster, and 
yellow streak. The hepatic cinnabar or liver ore contains 
carbonaceous matter and clay. Almost every variety shows 
glistening specks in the mass. Pure cinnabar is completely 
volatile. Roasted in air gives sulphurous fumes. Mixed 
with soda and heated in closed tube is decomposed and de- 
posits globules of mercury on cool sides of tube. These 



COPPER. 43 

tests readily distinguish it from cuprite and other red 
minerals. 

Cinnabar is the principal ore from which mercury is ob- 
tained. It usually occurs in veins associated with slates and 
shales. At Bahknut, in Southern Russia, it occurs impreg- 
nating a bed of sandstone, from which considerable mercury 
is obtained. The principal other mines are at Idria in Aus- 
tria, Almaden in Spain, and New Almaden in California. 
Some mercury is also obtained from Borneo, Mexico, and 
Servia. Mines, not now worked, exist in Chili, Peru, China 
and Japan, and several other countries. The Greeks are^ 
stated by Pliny to have obtained vermilion from Spain in 
700 B.C. Besides being the chief ore of mercury, pure 
cinnabar, under the name of vermilion, is used as a 
paint; for this purpose it is almost wholly an artificial 
preparation. 

Metallic mercury in this country is put up at the mines 
and transported in iron flasks weighing 76.5 pounds. 
Thus expressed, the world's product, for the past ten 
years, has been between 100,000 and 110,000 flasks, of 
which the United States produced about one-fourth. In 
1887 the product of the United States amounted to 80,000 
flasks. 



Native Copper. 

Isometric. In octahedrons and dodecahedrons, and modi- 
fied forms. The dendritic forms are frequently composed 
of aggregations of octahedrons. 

Copper has a red color and is very ductile and tenacious; 
when rubbed, emits a rather disagreeable odor; luster 
metallic ; streak red. H. = 2.5 to 3. G. = 8.8 to 8.95. Fuses 
before the blowpipe and oxidizes on surface in cooling; is 
acted upon by nitric acid, and the solution gives a blue 
color on addition of solution of ammonia. 

Native copper is widely distributed, and often contains a 
little silver. It generally occurs to a greater or less extent 



44 DESCRIPTIVE MINERALOGY. 

in connection with its ores, especially the carbonates and 
sulphides. Siberia and Cornwall have furnished very 
beautiful cabinet specimens ; Australia and the South Ameri- 
can countries afford it in greater quantity, Brazil especially 
having furnished some very large masses. The Lake 
Superior region of Michigan, however, is the most impor- 
tant locality in the world for native copper. The metal 
there occurs in layers, often called veins, distributed through 
amygdaloid and conglomerate and also in sandstone. Much 
of the copper contains a fraction of a per cent of silver in- 
timately alloyed. It also very frequently contains scattered 
grains and penetrating threads of silver. This mixture of 
copper and silver is found in other countries, and it has not 
been artificially imitated. The copper in the Lake Superior 
region is nearly all in the native state, and very large masses 
have been taken from the mines ; one weighing 420 tons 
and containing copper of 90 per cent purity was taken from 
the Minnesota mine in 1857. 

The gangue-stone contains generally from one to five per 
cent of copper. The mining operations of the largest com- 
pany (Hecla and Calumet) are simple, consisting of crushing 
and stamping the gangue and separating the metal by 
difference of specific gravity, the sands being washed away 
by running water. The machinery for this purpose is very 
extensive and perfectly adapted. The formations in which 
the copper occurs are not veins in any proper sense. They 
are most probably sedimentary formations whose original, 
position has been changed. The most important ores of 
copper are given below. 



ORES OF COPPER. 

The ores of copper are numerous and many of them not 
distinctly defined in composition. Only the more important 
will be described. 

The common wet test for a copper ore is to act upon the 
suspected mineral with nitric acid, dilute, and add ammonia; 
if copper is present, a blue solution is obtained. 



ORES OF COPPER. 45 

Chalcopyrite, Copper Pyrites, Copper and Iron Pyrites, CuFeS. y 

Is most commonly massive. Has a slighly greenish, 
bronze-yellow color, often iridescent by tarnish. Streak 
and powder greenish black. H. = 3.5 to 4. G. 4 to 4.3. 
Heated in the air before the blowpipe gives off sulphurous 
fumes and fuses to a magnetic globule ; this globule powdered 
and further heated on charcoal will reduce to a bead of 
iron and copper. Chalcopyrite must be well roasted before 
it will give the copper test with nitric acid and ammonia. 

It sometimes resembles native gold in color, or again 
iron pyrite. It is distinguished from the first by lack of 
malleability, and from the second by its softness, richer 
yellow color, and its greenish-black streak. 

Chalcopyrite is the ore from which the bulk of the 
copper of commerce is obtained. 

It occurs in veins intersecting metamorphic rocks and 
occasionally in cavities or veins in unchanged sedimentary 
rocks. Its most common associates are the copper carbon- 
ates and the sulphides of iron, lead, or zinc. 



Chalcocite, Copper Glance, Vitreous Copper, Cu 2 S. 

Occurs in crystals, but usually massive ; metallic luster ; 
color blackish lead-gray, often tarnished blue or green ; 
streak same as color, often glistening; slightly brittle. 
H. = 2.5 to 3. G. 3.5 to 5.8. Easily fusible by blowpipe 
on charcoal, giving sulphurous fumes and leaving a globule 
of copper. Acted upon by hot nitric acid with separation 
of sulphur ; nitric acid solution deposits copper on iron sur- 
face ; gives the usual copper test. 

The ore is not generally found pure, a portion of the 
copper being often replaced by iron. It occurs in great 
abundance and in nearly a pure form in several of the 
Montana mines. It is also an important ore in Arizona, 
Colorado, and New Mexico. 



46 DESCRIPTIVE MINERALOGY. 



Bornite, Erubescite, Variegated Copper 3(Cu,S,Fe 2 S 3 ). 

This in appearance is one of the most striking of the 
copper ores when in fresh condition. It then has a brilliant 
purplish-brown color, but changes on exposure to the air 
to many hues with varied iridescence. When pure it is 
represented by the formula 3(Cu 2 S,Fe,S 9 ), which may be 
written Cu,FeS,. The proportions of the constituent 
elements vary widely without materially affecting the 
general appearance of the ore. Has metallic luster; the 
streak is a dark grayish black. H. = 3. G. = 4.5 to 5.5. It 
is an important ore of the Butte mines. 

Before the blowpipe fuses easily to a black magnetic 
globule; this taken with its peculiar color and brilliant 
iridescence distinguishes it from chalcocite. 



Tetrahedrite, Gray Copper Ore. 

This mineral when pure is a double sulphide of copper 
and antimony. The antimony is frequently in part replaced 
by arsenic, and the copper by iron, zinc, silver, or lead. It 
is an unimportant ore in this country except when it 
becomes rich in silver, and is then valuable for the silver. 
This argentiferous form of the ore is found both in Mon- 
tana and Colorado. The pure tetrahedrite is represented 
by the formula 4Cu,S,Sb a S 8 . 

Tennantite. 

This mineral is essentially a sulphide of arsensic and 
copper ; it often contains antimony and graduates into the 
tetrahedrite. It is of no importance in this country as a 
copper ore. 

Cuprite, Red Copper Ore, Cu a O. 

Isometric. Prevailing form the octahedron, also in the 
derived forms. 



ORES OF COPPER. 47 

It occurs often massive and also earthy. Has different 
tints of deep red, often reddish gray ; luster adamantine or 
semi-metallic, dull in impure varieties; streak brownish red. 
H. = 3.5 to 4. G. 5.8 to 6.1. Heated on charcoal, reduces 
to metallic copper. Frequently occurs with the other 
copper ores ; outer surface often converted into carbonate. 
Gives copper test with nitric acid and ammonia. 



Melaconite, Black Copper Ore, CuO. 

Found as cubes in Lake Superior copper region, but 
generally in black masses and botryoidal concretions along 
with other copper ores. Important ore in some of the 
mines of this country, as in Tennessee. 

Tenorite is another variety of the same ore, found in the 
Vesuvian lavas and in earthy forms about copper lodes. 



Malachite, Green Hydrous Copper Carbonate, CuC0 3 ,CuO,H a O. 

Monoclinic. Crystals (rare in nature) generally tabular 
prisms. 

Usually occurs in incrusted masses with reniform, 
botryoidal, or mammillary surfaces with fibrous texture, 
often showing concretionary structure. Also compact or 
earthy. Color varies from emerald to nearly grass-green. 
Streak green, but generally lighter than mineral. Luster 
vitreous, pearly, or silky ; earthy varieties have little luster. 
H. = 3.5 to 4. G. = 3.7 to 4. Acted upon by the common 
mineral acids and gives the copper test with nitric acid and 
ammonia. 

Malachite is generally associated with other ores of 
copper; and when in sufficient quantity is a very valuable 
mineral. The incrustations made by it often have banded 
shades of green which give a very pleasing effect. It is 
susceptible of a high polish and is much used in indoor 
decorations, making beautiful mantels, table-tops, vases, 
etc. It is too soft for jewelry, though it is sometimes 



4 DESCRIPTIVE MINERALOGY. 

passed off as turquois, The mines of Siberia have given 
the largest quantity, though it occurs in a good many 
countries to a smaller extent. 

Azurite, Blue Hydrous Copper Carbonate. 

This mineral is very similar to malachite, but the 
color varies from azure-blue (the color of the powder) 
to indigo-blue ; its streak is also blue. These charac- 
teristics distinguish it from malachite ; it fulfills the tests 
given for that mineral. It is valuable when abundant, 
but occurs much less abundantly than malachite. Some- 
times used as a pigment, but is not very permanent. 
Contains a smaller per cent of copper than malachite. 

Chrysocolla, Hydrous Copper Silicate, CuOSi0 3 ,2H 2 0. 

This is an amorphous, compact mineral of bluish-green 
color ; sometimes occurs in thin layers, as incrustations ; 
and as botryoidal masses. H. = 2 to 4. G. = 2 to 2.4. 
Distinguished from the carbonates by its bluish-green 
color and no visible action with acids; very frequently 
contains the carbonate. Valuable as an ore when abun- 
dant. 

The world's product of copper in 1897 was about 
412,000 tons, of which the United States furnished more 
than one-half. Michigan, Montana, and Arizona in that 
year gave over eleven-twelfths of the yield of the United 
States. Only in the first-named State is the metal ob- 
tained in large quantity from the native form, elsewhere 
it is from the ores. The principal Montana ores are the 
different forms of copper sulphide in a siliceous gangue. 
Much silver is associated with the ores. The Arizona 
ores are largely the oxidized forms, though they frequently 
change to the sulphides in the lower reaches of the 
veins. 



OKES OF LEAD. 49 



ORES OF LEAD. 

Lead rarely occurs native, but exists in many compounds. 
It occurs combined with oxygen, sulphur, arsenic, tellurium, 
selenium, and as carbonates, sulphates, chromates, molyb- 
dates, and phosphates. Its principal ore is the sulphide. 

Galenite, Galena, Lead Sulphide, PbS. 

Isometric, Usually in cubes or some of the simpler de- 
rived forms ; also granular. It has metallic luster, bluish- 
gray color, streak slightly darker. H. 2.5. G. = 7 2 to 7.6. 
Before the blowpipe on charcoal it fuses readily and emits 
sulphurous fumes, coats the charcoal with lead oxide, and 
leaves a globule of lead. It is acted upon by strong nitric 
acid with separation of some sulphur ; this solution gives 
black precipitate with ammonium sulphide. 

Galena is a very widely distributed ore. It occurs both 
in veins and in beds or pockets, and both in metamorphic and 
unchanged rocks. Galena is very frequently associated with 
the sulphides of iron, copper, zinc, and silver. Some silver 
sulphide is nearly always present in galena ; when the silver 
becomes worth extracting the ore is called argentiferous 
galena. The argentiferous galena generally has a more 
micaceous appearance than the common ore. The gangue 
in lead-mines is generally calcite, quartz, or baryta, and 
sometimes fluor-spar. 

Abundant lead-ore deposits occur in the States of Iowa, 
Wisconsin, Missouri, and Illinois. None of these deposits 
come under the head of true veins, but are in sheets or beds 
between the strata. The sheets are usually only a few inches 
thick and are rarely accompanied by gangue or true vein- 
walls. The bed-deposits in this region are large, thick 
masses, as though underground caves or chambers had been 
filled by the ore. It is probable that the solvent waters that 
produced the caves also deposited the mineral from solution. 
Casts of fossils in galena are often found in the region, 



$0 DESCRIPTIVE MINERALOGY. 

showing the aqueous origin of the ore. Galena occurs in 
true veins in several of the Eastern States and in many of the 
Western. Of late years the greater portion of the lead pro- 
duced in the United States has been in connection with the 
gold and silver mining of the West, the lead being a by- 
product. In 1897 from this source there were obtained 
145,000 tons of lead, while only about 50,000 were obtained 
from other domestic sources. 

The greatest consumption of lead is in the manufacture 
of white lead, though large quantities are used in making 
pipes, shot, and sheeting. Galena is sometimes used for 
glazing coarse stoneware, being finely ground, mixed with 
other glaze material and applied to the vessels. 

Cerussite, White Lead Ore, Lead Carbonate, PbCO,. 

Orthorhombic. Cerussite occurs in orthorhombic crystals, 
often compound, but more generally the ore is found gran- 
ular compact, or in earthy masses. The crystalline forms, 
when pure, vary in color from white to dark gray, almost 
black ; the presence of copper gives blue or green tinge ; 
streak uncolored ; luster adamantine, vitreous to resinous, 
and pearly. H. 3 to 3.5. G. = 6.4 to 6.6. Brittle. Fuses 
readily before blowpipe and yields lead in reducing-flame ; 
acted upon with effervescence by nitric acid ; in closed tube 
it decrepitates, loses CO 2 , and turns brown or yellow. 

The lead carbonate is a very important ore at many 
mines in the Western States, especially in Colorado, Utah, 
and Nevada. The carbonate is formed from galena by 
meteoric agencies, and in these mines is generally found as 
loose sand or in compact lumps of a yellowish or brown 
color, due to the iron present ; clusters of crystals are also 
frequently present in the compact masses. 

Anglesite, Lead Sulphate. 

This ore of lead resembles cerussite and often occurs 
with it, both being formed from the sulphide. Its crystal- 



ORES OF ZINC. 51 

line system is the same as that of cerussite. It fuses readily, 
and in reducing-flame or with soda yields metallic lead. 
It is slightly soluble in nitric acid, but no effervescence 
which distinguishes it from the carbonate. This ore gener- 
ally accompanies cerussite in the mines of the Rocky Moun- 
tain region. 



ORES OF ZINC. 

If zinc occurs native, it has not been found in any con- 
siderable quantity. It has been reported from Australia, 
South Africa, Colorado, and Alabama, but satisfactory infor- 
mation has not yet been given in regard to these finds. Its 
compounds are pretty widely distributed ; they are the 
oxides, sulphides, carbonates, and silicates, all of which are 
used for obtaining the metal. 

Sphalerite, Blende, ZnS. 

Isometric. Prevailing forms, the octahedron and dodeca- 
hedron and modifications. Often massive and sometimes 
fibrous. 

The color of blende presents various shades of yellow, 
red, brown, and black; also gray to white and sometimes 
greenish. Luster resinous to waxy and sometimes semi- 
metallic. Streak is white to yellowish brown. H. 3.5 to 4. 
G. 3.9 to 4.2. The purer specimens will often become 
phosphorescent by friction in the dark. The sulphides of 
iron, cadmium, and lead are often present in it. It is fusible 
with difficulty by the blowpipe; heated in open tube gives 
sulphurous odor ; on charcoal gives yellow coating which 
turns white on cooling. It is acted upon by hydrochloric 
acid and emits hydrogen sulphide ; often shows efferves- 
cence. 

This ore occurs in many localities and in rocks of all 
ages. The lead-mines of the Mississippi valley afford it 
abundantly, as do the zinc-mines of Missouri arid Kansas. 
By oxidation the ore is converted into white vitriol. 



52 DESCRIPTIVE MINERALOGY. 

Zincite, ZnO. 

This ore generally occurs in tabular masses or dissemi- 
nated grains. Luster adamantine or semi-metallic ; its color 
varies from bright red to dark or brown ; streak is orange- 
yellow. H. =4.0 to 4.5. G. = 5.6 to 5.8. Acted upon by 
nitric acid. Yields yellow coating on charcoal, which turns 
white on cooling. It is a good ore of zinc, and is the ore of 
Sussex County, N. J. 

Smithsonite, Zinc Carbonate, ZnC0 3 . 

Rhombohedral. Smithsonite seldom occurs distinctly crys- 
tallized ; generally botryoidal, reniform, or stalactitic ; some- 
times granular or loosely compacted. This ore is of light 
color, but seldom white ; generally light gray or brownish 
white, sometimes shaded green, blue, or buff ; streak uncol- 
ored ; luster vitreous to pearly. Brittle. H. = 2 to 4. G. =' 
4.2 to 4.5. It is infusible before blowpipe alone ; with soda 
on charcoal gives a coating of zinc oxide ; effervesces in 
acid. 

This is a valuable ore of zinc, and is found abundantly in 
the mines of the Mississippi valley, also in Pennsylvania. 
It very generally accompanies galena and sphalerite. Cer- 
tain forms of it are termed dry-bone by miners. The carbon- 
ate in England is often called Calamine. 

Calamine, Hydrous Zinc Silicate. 

Orthorhombic. Crystalline forms seldom distinct. Cala- 
mine is a hydrous zinc silicate and closely resembles the 
carbonate in appearance and physical properties. It usu- 
ally occurs associated with the carbonate, and is found in 
the localities named above for that mineral. It gelatinizes, 
but does not effervesce with acids. It yields water in 
closed tube. 

Willemite, Zinc Silicate. 

Hexagonal, Rhombohedral. Occurs in long or short hexag- 
onal prisms ; also in massive, granular, and rounded forms. 



IRON. 53 

This mineral differs from calamine in composition in being 
anhydrous. 

Willemite varies in color from white and greenish yellow 
through light to dark brown. Its streak is uncolored ; 
luster vitreous or resinous. H. = 5.5. G. = 3.9 to 4.2. It 
fuses with difficulty, and gelatinizes with acids. Its com- 
position is Zn a SiO 4 ; a part of the zinc is sometimes replaced 
by manganese. It is frequently present with zincite and 
franklinite being thus found in New Jersey. 

Native Iron. 

Isometric. Generally massive. Native iron has gray 
color and streak; it is malleable and ductile. H. = 4.5. 
G. = 7.3 to 7.8. Acts on magnet. 

Native iron is of very limited occurrence ; there are 
two varieties, meteoric and telluric. Meteorites contain 
native iron usually alloyed with nickel in considerable 
quantity, and small quantities of cobalt and copper are often 
present. A polished surface of meteoric iron, when acted 
upon by nitric acid, will frequently show triangular figures 
indicating a coarse octahedral structure in crystallization. 
These figures are called Wiedmannstadt's figures, and 
when uniform in different specimens indicate an identical 
origin. Meteoric iron often contains nodules of iron 
monosulphide and the phosphide of iron and nickel 
(Schreibersite). Meteorites have been found in many 
places varying in size from an ounce in weight up to 
twenty tons. They are believed to have a non-terrestrial 
origin. 

Telluric iron is native iron of terrestrial origin. It is 
found as imbedded particles or grains in some basaltic rocks. 
Masses have also been found ; one weighing twenty tons 
was found on Disco Island, Greenland, in 1870. It is 
thought probable that this telluric iron has been pro- 
duced by the reduction of the iron-bearing minerals in 
the passage of the containing rock through carbonaceous, 
strata. 



54 DESCRIPTIVE MINERALOGY. 



ORES OF IRON. 

The ores of iron are the oxides, carbonates, and sul- 
phides. The oxidized forms and the silicates are very 
widely distributed as the common coloring matter of soils. 
The ores, when heated in the reducing flame of a blow- 
pipe, become magnetic, and when treated with hydrochloric 
acid give a blue precipitate on the addition of potassium 
lerrocyanide. 

Pyrite, Iron Pyrites, FeS 2 . 

Isometric. Usually in cubes, faces frequently striated ; 
striae of adjoining faces are always perpendicular to each 
other. Occurs in forms derived from cube, also in globular 
nodules with radiated structure. 

Pyrite has generally a brass-yellow color, sometimes 
brownish by surface alteration ; is brittle, and has metallic 
luster. H. = 6 to 6.5 ; will strike fire with steel. G. 4 to 5. 
Streak is brownish black. Roasted before the blowpipe 
gives sulphurous fumes and leaves a globule fusible with dif- 
ficulty and attracted by the magnet. It resembles copper 
pyrites, but is of a lighter color, harder, and has different 
streak. It is readily distinguished from gold by its hardness 
and brittleness. 

Pyrite is one of the most widely distributed of ores, but 
is more generally employed to obtain sulphur than iron. It 
occurs in rocks of all ages. In auriferous regions it often 
contains gold, and is sometimes worked to obtain that metal. 
Owing to its common occurrence in rocks and its change- 
able nature it is one of the chief natural causes of rock dis- 
integration. No stone containing it should be used for 
building purposes. The disintegration of the rock contain- 
ing it is brought about by the oxidation of the pyrite and 
the solution of the resulting compound. Other sulphides 
of iron have the same effect on the containing rock. Pyrite 
is used in the manufacture of sulphuric acid, alum, green 



ORES OF IRON. 55 

vitriol, and sulphur ; occasionally the iron is extracted. 
Pyrite is sometimes called mundic and fool's gold by miners. 

Pyrrhotite, Magnetic Pyrites, Fe 7 S 8 . 

Hexagonal. The crystals of this mineral belong to the 
hexagonal system, but well-defined crystals are rare. It 
usually occurs massive or disseminated in granular or scaly 
aggregates. 

Pyrrhotite is a sulphide of iron whose general formula 
is Fe M S M + I , in which n may vary from 5 to 16; the average 
composition is accepted to be indicated by Fe 7 S 8 , which 
gives the percentage composition S = 39.6, Fe = 60.4. Its 
color is generally between bronze-yellow and copper-red ; it 
readily tarnishes to a dull bronze ; streak grayish black. 
H. = 3. 5 to 4.5. G. =4.5 to 4.7. Brittle and slightly mag- 
netic ; powder attracted by magnet. Its color and magnetic 
properties distinguish it from chalcopyrite ; these charac- 
ters and its inferior hardness from pyrite. It is acted upon 
by HC1, yielding H 3 S ; before the blowpipe on charcoal 
gives magnetic globule. 

Pyrrhotite is found in small quantities at many places, 
and is sometimes used as an ore of sulphur in the manufacture 
of sulphuric acid. It is often present in meteoric iron, 
though the monosulphide FeS, troilite, is the principal sul- 
phide of meteorites. 

Mispickel, Arsenopyrite, Sulpharsenide of Iron, FeAsS. 

Its color is steel-gray or tin-white. Metallic luster; 
streak grayish black. H. = 5.5 to 6. G. = 6 to 6.4. It is 
brittle, and the texture often granular, giving slightly hackly 
fracture. Heated in closed tube gives red and yellow sub- 
limates of arsenic sulphide and also a metallic-like deposit 
of arsenic; roasted before the blowpipe gives strong garlic 
odor of arsenious oxide and leaves a globule attracted by 
the magnet ; when struck sharply with a steel it gives the 
same odor. It is very frequently associated with the ores of 



56 DESCRIPTIVE MINERALOGY. 

silver and lead and the sulphides of iron, copper, and zinc. 
Cobalt sometimes replaces some of the iron in mispickel, 
such compound being one of the ores of cobalt. Mispickel 
is one of the chief ores of arsenic. 



Hematite, Specular Iron Ore, Fe 2 3 . 

Rhombohedral. Often in granular masses, compact or 
friable; also lamellar, micaceous, and earthy; also in botry- 
oidal and stalactitic forms. 

The color of the metallic varieties varies from iron-black 
to steel-gray, the crystals often iridescent. Luster metallic, 
of crystals brilliant ; streak cherry-red to brownish red. 
H. = 5.5 to 6.5. G. 4.5 to5.3. Sometimes slightly mag- 
netic. The compact and earthy varieties have not the luster 
or color of the metallic, but give the same streak. Acted 
upon by hydrochloric acid, and gives blue precipitate upon 
addition of potassium ferrocyanide. 

The more important varieties of the hematite are the 
following : 

Specular. With distinct metallic luster. 

Red Hematite. Dark or brownish-red color, semi-metallic 
luster. 

Micaceous. In thin scales, schistose structure. 

Ocherous. The red earthy varieties often containing 
clay ; when soft and pulverulent, red ocher ; when harder, 
compact, and of fine texture, it is red chalk. 

Argillaceous. Includes compact red and brownish-red 
varieties, often of semi-metallic luster. Composed of the 
oxide, with sand, clay, and often other impurities. The 
most compact of these varieties, with a jasper-like texture 
and appearance, is the jasper clay ore. The less hard and 
jaspery gives the clay iron-stone variety. This last name is 
also applied to the clayey siderite and limonite. 

When made of flattened concretions or grains it is the 
lenticular ore. The argillaceous varieties give the red or 
brownish-red streak. When heated in the reducing-flame 
hematite easily becomes magnetic. Acted upon by hydro- 



O&ES OF IRON. 57 

ch/oric acid, and gives blue precipitate with potassium 
ferrocyanide. These tests, with its red streak, serve to 
distinguish the mineral. 

Martite has the same composition as hematite, but crys- 
tallizes in isometric forms, octahedrons, dodecahedrons, 
which are thought to be pseudomorphous of magnetite ; 
the color is iron-black, luster sub-metallic; the streak is 
purplish-brown, and the mineral but slightly, if at all, mag- 
netic. These characters distinguish it from magnetite. It 
is of frequent occurrence in magnetic regions. 

Hematite is one of the most common and widely dis- 
tributed of ores, and occurs in rocks of all ages. It is found 
in so many localities that only a few can be named. The 
island of Elba has been celebrated for this ore since before 
the Christian era, and it still produces it. The ore of the 
two so-called iron mountains of Missouri was mainly hema- 
tite ; it is an abundant ore of the Marquette region, Michi- 
gan, and is found at many other places in the United 
States ; when pure, it is less easy to work than the other 
oxidized ores. 

The pulverized ore is used for metal polishing. The 
artificially prepared oxide furnishes the Venetian-red paint, 
and the red chalk is used for crayons and coarse pencils. 

Magnetite, Magnetic Iron Ore, Fe 3 4 . 

Isometric. Prevailing crystalline forms the octahedron 
and dodecahedron ; very commonly massive and granular. 

The color of the ore is distinct iron-black, luster semi- 
metallic, streak black. H. = 5.5 to 6.5. G. = 4 to 5. It is 
magnetic and sometimes endowed with polarity. Acted 
upon by hydrochloric acid, and gives blue precipitate upon 
addition of potassium ferrocyanide. The weight, streak, 
and magnetic properties distinguish this ore from alj other 
minerals. 

Magnetite occurs in beds, principally in metamorphic 
rocks, and is most abundant in the Archean. It is found in 
many places throughout the world. It is the principal ore 



58 DESCRIPTIVE MINERALOGY. 

-of Sweden and Norway, and exists in extensive beds in 
New York and to a less extent in several of the New Eng- 
land States. 

Franklinite. 

This ore is similar to magnetite, but some of the iron has 
been replaced by zinc and manganese. Its physical proper- 
ties are about the same as magnetite, but the streak is 
generally not so black, often a reddish brown. This ore 
occurs abundantly in New Jersey and often contains zincite. 
The franklinite is a valuable ore for the manufacture of zinc- 
white and Spiegeleisen. 



Limonite, Brown Hematite, 2Fe 2 3 ,30H 2 . 

This ore occurs in botryoidal, mammillary, and stalac- 
titic forms with fibrous texture ; also massive, and as con- 
cretions and earthy. 

The color is brown to black, and in the earthy varieties 
yellowish brown. Streak yellowish brown. Luster, when 
present, semi-metallic, sometimes silky ; it is frequently 
without luster, especially in the earthy forms. H. = 5 to 5.5. 
G. greater than 4 ; pulverulent varieties less hard and less 
heavy. 

The principal forms of the ore are the following : 

Brown Hematite, which includes the more compact forms, 
usually with semi-metallic luster, the botryoidal, stalac- 
titic, etc. 

Ocherous Ore. All soft, earthy varieties of brown or 
yellowish color, giving the brown and yellow ochers. 

Impure compact, clayey ores constitute the brown and 
yellow clay iron-stone. 

Bog Ore is a soft brownish-black ore when pure. It 
sometimes takes imitative forms, and when mixed with silica, 
which is very frequently the case, is quite hard. 

These ores give off water in a closed tube readily, be- 
come magnetic before the blowpipe, and give the iron test 



OKES OF IRON. 59 

with hydrochloric acid and potassium ferrocyanide. These 
characters with the streak distinguish the ore. 

Limonite is a common and valuable ore and is abundantly 
and widely distributed in the United States. The localities 
of its occurrence are too numerous to mention. The ore is 
the result of the alteration of iron-bearing minerals, brought 
about by atmospheric agencies. The yellow ocher is used 
for a common paint. The name limonite is from the Greek 
word for meadow. 

Siderite, Spathic Iron Ore, Chalybite, Iron Carbonate, FeC0 3 . 

Rhombohedral. Occurs also in botryoidal and nodular 
forms, in compact masses and earthy. Crystalline form 
shows sparry faces which are often curved. 

Color of mineral is ash-gray to yellowish gray, yellow 
to reddish brown, often brown to brownish black from 
exposure. Luster pearly to vitreous, also dull. Streak 
light yellow to yellowish brown. H. 4. G.=4. Before the 
blowpipe it blackens and becomes magnetic. When pow- 
dered acted upon with effervescence by hydrochloric acid, 
and gives a blue precipitate upon addition of potassium 
ferrocyanide. 

Spathic Ore is the crystallized form with sparry faces. 
When the ore is largely mixed with clay it gives the clay 
iron-stone, and when bituminous matter is present it is the 
black band. 

It is a valuable ore, occurring as the gangue in certain 
veins, and in beds, and is abundant as clay iron-stone in 
the coal formations. It takes the limonite color when 
exposed to atmospheric agencies due to conversion into 
that form. Chalybeate waters hold it in solution and 
deposit it upon coming to the surface, the color around 
such springs being due to its conversion into hydrated 
sesquioxide. 

The clay iron-stone constitutes the great ore of England. 
It occurs also in the coal-beds of Pennsylvania, West Vir- 
ginia, and Ohio. The United States now produces more 



6O DESCRIPTIVE MINERALOGY. 

iron than any other country in the world, England coming 
next in production with nearly as much. 

Chromite, Chromic Iron Ore, FeCr 2 4 or FeOCr 2 3 . 

Isometric. Chromite usually occurs in granular or com- 
pact masses or in disseminated grains. Color is brownish 
black to iron-black ; streak brown. H. = 5.5. G. 4.3 to 4.6. 
Sometimes slightly magnetic. It is distinguished from 
magnetite by its streak and by giving a green bead indic- 
ative of chromium when fused with borax. 

Chromite is the source of nearly all the compounds of 
chromium which are so extensively used as pigments, its 
principal use being in the production of potassium bi- 
chromate. 

Stibnite, Gray Antimony, Antimony Glance. 

Orthorhombic. Crystals prismatic, long columnar or acicu- 
lar, faces vertically striated ; pyramidal faces curved or 
distorted ; common in radiating or divergent groups of 
acicular crystals, also massive with columnar fibrous 
texture. 

Stibnite is the sesquisulphide of antimony, Sb a S t . Its 
color is lead-gray ; luster metallic, very brilliant on fresh 
cleavage surface ; tarnishes black, sometimes iridescent ; 
streak lead-gray. H. = 2. G. = 4.55 to 4.65. 

Heated in open tube stibnite gives off sulphurous and 
antimonial fumes, the latter being partly Sb 2 O 3 and partly 
Sb 2 O 4 ; the first oxide is fusible and volatile, the latter 
neither. Stibnite is easily fusible and entirely volatile 
before the blowpipe ; when pure it is acted upon by 
HC1 with evolution of H 3 S. The above characters dis- 
tinguish it from galena and graphite, which it sometimes 
resembles. 

Stibnite is the chief ore of antimony, besides being 
directly used as a substitute for sulphur in some prepara- 
tions. 



OXIDES. 6 1 



Pyrolusite, Black Oxide of Manganese, Mn0 2 . 

Pyrolusite occurs in orthorhombic crystals, but may be 
pseudomorphous. Generally occurs in short columns, often 
parallel fibrous and divergent, granular massive and reni- 
form, also compact. 

Pyrolusite is the dioxide of manganese, MnO a . Its color 
is dark gray to iron-black, sometimes bluish ; luster almost 
metallic ; streak black. Crystals have a hardness of 2 to 2.5, 
other varieties softer. G = 4.7 to 4.9. 

Fused with borax gives violet bead of manganese ; acted 
upon by HC1 with evolution of Cl. 

Pyrolusite is the most important ore of manganese, being 
employed both for its manganese and oxygen, and for 
making bleaching-powder. 

Manganite is a hydrous manganese sesquioxide. Its 
streak is generally less dark than that of pyrolusite ; it is 
also harder and yields water in a closed tube. 

Psilomelane and wad are minerals largely composed of 
oxides of, manganese of varying degrees of purity, but whose 
compositions are not definite. 

Cassiterite, Tin-stone, Black Tin, Tine Ore, Tin Oxide, Sn0 2 . 

Tetragonal. Occurs in crystals of short pyramidal type 
or slender columns acutely terminated, twins common ; also 
in reniform and spheroidal masses with divergent fibrous 
texture ; in granular masses and in rounded pebbles. 

The color is sometimes white, gray, yellow, or red, but 
more generally brown or black ; streak light gray to brown. 
H. 6 to 7. G. = 6.8 to 7.1. Before blowpipe infusible 
alone, gives globule of tin on charcoal with soda. 

Stream-tin ore is the detritus from veins and is found in 
the alluvial deposits of streams which drain tin-bearing re- 
gions. The globular masses of tin ore with radiating 
fibrous texture and concentric structure are sometimes called 
wood-tin, from the woody appearance. 



62 DESCRIPTIVE MINERALOGY. 

Cassiterite is the principal ore of tin. It occurs in veins 
intersecting granite and metamorphic rocks. The largest 
amounts of tin are produced in the island of Banca and in 
Great Britain ; considerable quantities also come from Ger- 
many, Austria, Siberia, Australia, and Bolivia. Tin has as 
yet been produced only in very small quantity in this 
country. 

Rutile. 

Tetragonal. Often in twinned crystals ; in prisms of four, 
eight, or more sides, faces of prisms usually striated verti- 
cally ; often in fibrous acicular aggregates penetrating 
quartz ; sometimes massive. 

Rutile is the dioxide of titanium, TiO 2 . Its color is red- 
dish brown to red, passing through violet, bluish to black, 
sometimes yellowish ; luster adamantine or metallic ; streak 
pale brown. H. = 6 to 6.5. G. = 4.2 to 4.3. 

It occurs in the more distinctly crystalline rocks, both 
metamorphic and plutonic. 

It is frequently found penetrating quartz in acicular 
needles or hair-like fibers ; polished stones of this kind are 
sometimes very beautiful and constitute what the French 
have called " fleches d'amour." 



Corundum, A1 2 3 . 

Rhombohedral. Generally in combinations of six-sided 
prisms and acute pyramids, often with uneven and irregular 
surfaces, also massive and fine or coarse granular. 

Corundum is the sesquioxide of aluminum ; the uncrys- 
tallized varieties usually show a small per cent of iron. 

Corundum is sometimes colorless, but generally some 
shade of blue, red, or yellow, massive forms often brown or 
black ; streak uncolored ; luster adamantine to vitreous, 
sometimes pearly on bases. H. =9. G. == 3.9 to 4.1. B.B. 
infusible. 

Corundum is distinguished by its great hardness, infusi- 
bility, high specific gravity, and its luster. 



OXIDES. 6$ 

Sapphire or oriental ruby are the names applied to clear 
crystals of fine colors; blue is the true sapphire color; 
true ruby is red, highly prized as a gem. 

Corundum is the name applied to the dull irregularly 
colored crystals and masses as well as to the species. 

Emery includes the granular varieties, usually of dark 
color from presence of magnetite. 

Corundum, the species, occurs in crystalline rocks, both 
plutonic and metamorphic. Burmah and Ceylon are cele- 
brated for their rubies and sapphires ; many fine gems have 
been secured in this country, the finds in North Carolina 
and Montana being most numerous. Corundum is mined in 
North Carolina, and emery in Massachusetts and New 
York. Corundum and emery are crushed to powders of 
different fineness and used for polishing. 

Diaspore is the hydrous oxide of aluminum, A1,O 8 ,H 3 O ; 
it is usually found with corundum. 



lswft* 



Bauxite, Beau 

Bauxite is a clay-like mineral found also in grains, con- 
cretions, and massive. It is a hydrated aluminum oxide, 
Al 2 O 3 ,2H a O; iron is frequently present, replacing some of 
the aluminum. 

Its color varies from white through gray to yellow and 
brown ; in its purer forms it is largely used in France in the 
preparation of the alums and also in the manufacture of 
aluminum. 

Turquois. 

Turquois is a hydrous aluminum phosphate. It has a 
bluish-green color, vitreous to waxy luster. H. = 6. G. = 
2.6 to 2.8. When heated before the blowpipe it gives off 
water and turns brown ; infusible, but dissolves quietly in 
hydrochloric acid. It often contains from one to five per 
cent of copper, also a little iron and manganese. 

It has been found in New York, Arizona, and Nevada in 



64 DESCRIPTIVE MINERALOGY. 

this country, and in several places abroad. It is susceptible 
of high polish and is used as a gem. 



Monazite. 

Monazite is a phosphate of the cerium group of metals. 
It has come into considerable prominence in the past years 
as the source of cerium oxide and other infusible earths. It 
contains cerium, lanthanum, thorium, didymium. It is now 
found in greatest quantity in rolled sands in Brazil ; under 
similar conditions considerable quantity has been obtained 
from North Carolina. 

Spinel. 

Isometric. Occurs only in crystals, usually in octa. 
hedrons. 

Spinel is an aluminate of magnesium (MgO,Al a O 3 ) ; the 
magnesium is often partly replaced by iron or manganese, 
and the aluminum by iron or chromium. The color is 
occasionally white, but more generally some shade of red, 
brown, blue, or green ; streak white ; luster vitreous. H. = 
8. G. = 3. 5 to 4.1. B.B. infusible. Its most evident dis- 
tinctions are its hardness, infusibility, and octahedral form. 

Spinel occurs imbedded in granular limestone, serpen- 
tine, and other metamorphic rocks ; also in volcanic rocks. 
The spinels of fine color are prized as gems ; the red spinel 
is the common ruby of jewelry ; it often resembles the true 
ruby (corundum), but the latter never occurs in octahedrons. 

Chrysoberyl. 

Orthorhombic. Occurs in short columnar or thick tabular 
crystals. Often forms compound crystals, like irregular 
six-pointed stars. 

Chrysoberyl is an aluminate of beryllium. Its color 
varies through several shades of green, occasionally rasp- 
berry by transmitted light, pleochroic ; streak uncolored ; 



COMPOUNDS OF SODIUM AND POTASSIUM. 6$ 

luster vitreous. H. = 8.5. G. = 3.5 to 3.8. B.B. alone in- 
fusible. 

Its hardness, infusibility, and tabular crystals and high 
specific gravity, taken in connection with its greenish color, 
are its most evident characteristics which distinguish it from 
resembling minerals. 

Chrysoberyl is found in this country in Connecticut,Maine, 
New Hampshire, and New York. The finest crystals make 
beautiful gems. Two varieties of the species are : 

Alexandrite, which is an emerald-green chrysoberyl, sup- 
posed to be colored by chromium. 

Cat's-eye has a greenish color and exhibits chatoyant 
effects. 

Halite, Rock Salt, NaCl. 

Isometric. Cube the prevailing form. 

Rock salt is sometimes transparent and colorless, though 
often tinged some shade of yellow, red, or green. Its taste 
is well known. H. = 2. G. 2.2. Decrepitates when heated, 
easily fusible, and colors flame yellow. It is soluble in 
water and gives a white precipitate with silver nitrate. 

Salt exists in all geological formations from the Silurian 
up. It is found in beds extending over large areas and is 
usually associated with gypsum, anhydrite, clays, or sand- 
stone. In some places the salt is mined, or taken in the 
solid state directly from the beds; in others the waters 
from brine-springs are evaporated. The salt-mines of Po- 
land and Hungary are the most celebrated in the world. 
The first, near Cracow, have been worked for over seven 
centuries and are almost of inexhaustible extent. Salt is 
mined in this country in Louisiana, and Kansas, and in 
Wyoming, Genessee, and Livingston counties, New York. 

Most of the salt made in the United States is by the 
evaporation of brines or waters from salt-springs. Michi- 
gan and New York are the chief producers by this method, 
though other States furnish some. The rock salt taken 
from mines is generally so impure that it is dissolved and 
recrystallized by evaporation before going into the market. 



66 DESCRIPTIVE MINERALOGY. 

Salt is also made in some places by the evaporation of sea- 
water or the water of salt lakes. The consumption of salt 
in the United States is about one bushel per capita, and the 
productive capacity is considerably more than this. 



Cryolite, Ice-stone, Double Fluoride of Sodium and Aluminum, 
Na,AlF B or 3NaF,AlF,. 

Monoclinic. Cryolite usually occurs massive, generally 
white, though sometimes giving shades from red through 
brown to black ; translucent ; has an irregular platy or 
fibrous fracture which is very characteristic. It fuses 
readily in forceps, coloring flame yellow ; on charcoal easily 
yields clear bead ; acted upon by sulphuric acid with evolu- 
tion of hydrofluoric acid. 

This mineral is largely used in the production of alumi- 
num and formerly of sodium. It is principally obtained at 
the Ivigtut mines of west Greenland, from which place it is. 
largely imported to the United States. 



Niter, Saltpeter, KNO. 

Orthorhombic. Niter, when pure, is white and very brit- 
tie. It has a saline and cooling taste. H. = 2. G. = 1.97. 
Deflagrates when heated with powdered charcoal. Differs 
from sodium nitrate in not deliquescing when exposed to 
the air. 

Niter is sometimes found mixed with the earthy flooring 
of caves ; Kentucky, Tennessee, and several Western States 
have furnished it in small quantity from this source. It 
forms abundantly as an efflorescence on the soil in certain 
countries, especially during hot weather after rains. India 
and Persia are the most noted countries for this natural 
production. In many countries it is artificially prepared as 
described in Chemistry. 



COMPOUNDS OF CALCIUM. 67 



Carnallite. 

Hydrous chloride of potassium and magnesium. 

This mineral occurs in granular masses. It is of white 
color when pure, but generally reddish ; has a bitter taste 
and is deliquescent ; showing greasy luster when fresh. 

Carnallite is found in large quantity alternating with 
beds of common salt at the Stassfurt salt-mines. It is the 
principal source of potassium chlorid,e. 

Its composition is represented by the formula 

KMgCl s ,6H,0. 

COMPOUNDS OF CALCIUM. 

These compounds are very abundant in the mineral 
kingdom. The most abundant and important are the car- 
bonates, sulphates, phosphates, silicates, and the fluoride. 
The carbonate is one of the most common of minerals ; 
other native compounds are found less commonly. The 
compounds named are insoluble or only very slightly solu- 
ble in water. 

Fluorite, Fluor Spar, CaF 2 . 

Isometric. Prevailing form is the cube; also frequently 
compact and fine granular. It is sometimes colorless and 
transparent, but usually has some light color, e.g., some 
tint of green, blue, purple, or yellow ; rose-red and violet 
shades are rare and highly prized. Streak light. H. = 4* 
G. = 3. Below red heat the mineral phosphoresces, but 
above that temperature it ceases to phosphoresce and loses 
its color. The phosphorescent colors are independent of 
the actual colors. That giving a green phosphorescence 
is called chlorophane. Before the blowpipe the mineral de- 
crepitates. It is very brittle. 

Fluorite occurs in veins, also in beds, and sometimes as, 
the gangue in metalliferous veins, especially of lead and 



68 DESCRIPTIVE MINERALOGY 

tin. It is the most abundant native compound of fluorine* 
The massive varieties are worked into vases, candlesticks, 
and ornamental objects. It takes a high polish, but is diffi- 
cult to work because of its brittleness. It is decomposed 
by sulphuric acid, with liberation of hydrofluoric acid, and 
is used to obtain this acid for etching on glass. It is also 
used as a flux in certain metallurgic operations. The Cum- 
berland and Derbyshire districts of England are most noted 
for its production. 

Gypsum, Hydrous Calcium Sulphate, CaS0 4 ,20H 2 . 

Monoclinic. Crystals frequently of arrow-head form. 
Occurs massive with foliated and granular texture, also 
fibrous and in radiating forms. 

Gypsum varies in color from white to yellow, red, brown, 
and black. The crystals are generally more or less trans- 
parent, other forms translucent to opaque. Luster silky, 
vitreous to pearly. H. = 2. G. = 2.3. In thin plates flex- 
ible, but not elastic. Before the blowpipe loses water, 
becomes white, opaque, and exfoliates. In closed tube gives 
off water easily ; dissolves in hydrochloric acid, and after 
dilution gives a white precipitate with a soluble barium 
salt. 

Gypsum is the most widely distributed of the sul- 
phates, and there are several varieties. 

Alabaster. This has a very fine granular texture, almost 
compact to the eye. 

Selenite. Includes the crystalline forms, usually in trans- 
parent plates. 

Satin Spar. A white, finely fibrous variety. Some of 
, the fibrous varieties have a radiated structure and are then 
called Radiated Gypsum. 

Common Gypsum. Compact and fine granular, may be 
white, yellow, brown, red, or black. Gypsum occurs in ex- 
tensive beds in limestone and clay strata. Common salt is a 
very frequent mineral associate. When three-fourths of its 
water is driven off from gypsum by heat it constitutes plaster 



COMPOUNDS OF CALCIUM. 69 

of Paris, so called because the gypsum quarries near Paris 
have long been famous for supplying it. The plaster mixed 
with water is used in taking casts, making moldings, etc. 
Alabaster is carved into various objects, as statuettes, parlor 
ornaments, etc. The name of alabaster is sometimes applied 
to a variety of calcium carbonate. Gypsum, finely divided, 
is also used as a fertilizer. 



Anhydrite, CaS0 4 . 

This mineral resembles gypsum, and its tests are the 
same except that it gives off no water when heated. It is 
also harder and heavier than gypsum, and its crystalline 
form is orthorhombic. H. = 3 to 3.5. G. = 3. 



Apatite, Calcium Phosphate, with Chlorine and Fluorine. 

Hexagonal. Prevailing form hexagonal prism ; also 
massive, sometimes globular with fibrous texture. 

Color is usually some shade of green, but may be white, 
yellow, reddish yellow, or brown. Luster vitreous to sub- 
resinous, streak light. H. = 5. G. = 3.2. It often closely 
resembles beryl in appearance, but is softer and more resin- 
ous. It is readily soluble in hot nitric and hydrochloric 
acids. Solutions treated with sulphuric acid give a 
white precipitate. Nitric acid solution added to molybdate 
of ammonium in excess gives immediately, or upon warm- 
ing, a bright yellow precipitate. 

Calcium phosphate is the main constituent of animal 
bones. Coprolites and guano are the fossil excrements of 
birds, and are chiefly composed of calcium phosphate, but 
contain also the phosphates of ammonium, sodium, and mag- 
nesium. 

Apatite occurs in veins in Quebec and Ontario, often of 
great purity, but generally mixed with rock material, such 
as pyroxene, hornblende, calcite, and many others. Im- 
mense deposits of phosphatic nodules occur in the Tertiary 
formations of South Carolina and Florida. These nodules 



7O DESCRIPTIVE MINERALOGY. 

contain from fifty to sixty per cent of tricalcic phosphate 
mixed with sand, calcium carbonate, and some organic 
matter. The great importance of guano and apatite is due 
to the phosphoric acid in their composition. Both are val- 
uable fertilizers. The apatite, before use, is converted into 
the soluble superphosphate of calcium by treatment with 
sulphuric acid. The phosphate industries of the United 
States are very important and extensive. 

Calcite, Calcspar, CaCO s . 

Rhombohedral. Often coarse and fine fibrous, granular, 
compact, and earthy. 

There are many varieties of this mineral, and they vary 
very much in color, from transparent white to yellow, red, 
and mottled in the crystalline forms ; the compact forms 
may be almost any dull shade to black. Typical crystals 
have vitreous luster, sometimes pearly; fibrous variety is 
often silky ; the others, from common to earthy in appear- 
ance. Hardness (of crystals) 3. G. = 2.5 to 2.8. Some of the 
earthy forms are very soft. Calcite is infusible, but when 
heated gives off carbon dioxide and is reduced to quick- 
lime, which when moistened gives alkaline reaction ; it is 
acted upon readily, with effervescence, by the mineral 
acids even when cold ; the solution in hydrochloric acid 
diluted gives a white precipitate upon addition of sulphuric 
acid. 

Calcite is one of the most abundant and widely distrib- 
uted of minerals, probably coming next to quartz in this re- 
spect. Some of the most important varieties are mentioned 
below. 

Limestone. This term is sometimes, and not improperly, 
applied to all calcspars, but it is generally limited to the 
granular and compact varieties. The granular include those 
of a distinct crystalline granular texture, often glistening 
owing to the facets of the grains ; architectural and statuary 
marbles are the best examples. The latter must be of fine 
grain, homogeneous texture, and pure color. The architec- 



COMPOUNDS OF CALCIUM. 71 

tural varieties may be of various shades of color and is used 
for decorations as well as in structures. 

The compact limestones include the crypto- crystalline 
and non-crystalline varieties. Hydraulic limestone is one of 
these ; it contains clay as an impurity, and produces a lime 
that yields a mortar that will set under water. Slow ef- 
fervescence, conchoidal fracture, and argillaceous odor inci- 
cate, but do not insure, hydraulic properties. 

Lithographic Limestone. A very fine-grained compact 
limestone ; its use is indicated by the name. 

Oolitic Limestone. Compact and often composed of con- 
cretionary grains somewhat resembling the roe of a fish, 
hence the name, from the Greek oon, an egg. If the grains 
are larger, the stone is called pisolite, from the Latin pisum^ 
a pea. The grains are not always concretionary, but some- 
times comminuted and rounded fragments. In each case 
the grains are cemented together by calcium carbonate. 

Chalk. A compact but soft variety, mainly composed of 
rhizopod shells. 

Chemically deposited Limestone. Under this head are in- 
cluded the limestones deposited from water holding them in 
solution. Some of the most important are: , 

Travertine. Deposited from rivers and springs ; it is 
often in variegated layers and makes a most ornamental 
marble. Mexican onyx is an illustration. 

Stalactites. The cones and cylinders found depending 
from the roofs of many caves. 

Stalagmites. Calcareous formations over the bottoms of 
caves and often rising in cones, meeting similar projections 
from above. These cave formations are frequently arranged 
in different colored curved layers, and when broken across 
give very beautiful effects. The cave deposits are made by 
the waters which percolate into the caves. Luray Cave in 
Virginia is one of the most celebrated in the world for these 
formations. 

Calcareous Tufa. An irregular porous deposit frequently 
incrusting twigs or similar objects and usually made by 
small springs and rather turbulent waters. 



DESCR 



v i. 



Rock 
deposited from spring 

In the case of all t h 
first taken into solutio 1 
solution, and is depos 
water, or in some ca >< 
itself. 

Of the non-massiv , 
only necessary to mention a few : 

Iceland Spar. The name applied to the limpid, crystal- 
line specimens. 

Dog-tooth Spar. Composed of crystals of scalenohedral 
form ; frequently occurs as an incrustation. 

Satin Spar. The delicately fibrous variety, affording a 
fine satin luster after polishing. 

In addition to the varieties above described calcite occurs 
in many other forms. The living and often fossil shells of 
the mollusca are mainly composed of it as well as the many 
forms of shell-limestone and coral-rock. It is also an essen- 
tial constituent of marls. The granular and compact lime- 
stones constitute immense rock formations in nearly all geo- 
logical, ages and are found widely distributed. True chalk 
is abundant in Europe, especially in England, but has only 
been found in Texas and Kansas in this country. Marble is 
a term applied to any limestone susceptible of a polish. 
Besides its use in structures, limestone is the source of quick- 
lime, which is employed in enormous quantity throughout 
the world for making common mortar. 



Arragonite, CaCO s . 

This mineral has the same chemical composition as cal~ 
cite, but differs in crystalline form, being orthorhombic ; it 
is also slightly harder and heavier. The action under the 
blowpipe and acids is the same as that of calcite, except 
that it crumbles to powder more easily after heating. It 
receives its name from Arragon in Spain, where very fine 
crystals have been found. 



COMPOUNDS OF CALCIUM. 73; 

Dolomite, Calcium-magnesium Carbonate, Magnesium Limestone, 

CaMg(CO,) a . 

Rhombohedral. Granular and massive. 

The massive varieties of dolomite vary in color from white 
to gray, yellow, reddish, green to brown or black. The 
lighter varieties have vitreous or pearly luster. H. = 3.5 to 4. 
G. = 2.8 to 2.9, slightly harder and heavier than calcite. 
Before the blowpipe reacts the same as calcite. It gives 
sluggish effervescence with cold dilute acid, sometimes has 
to be powdered for this action. It often cannot be distin- 
guished from calcite without a chemical analysis. 

Dolomite is a double carbonate of calcium and mag- 
nesium and forms beds in rocks of all ages. It occurs 
mainly in two forms : 

1. The distinctly crystalline granular variety, usually of 
white or yellowish-white colors, is generally designated as 
Dolomite. Its external characters are often hard to distin- 
guish from granular limestone. 

2. The finely granular, almost compact variety is gener- 
ally called Magnesium limestone ; it is often difficult to 
distinguish from siliceous limestone. 

Dolomite is a common marble in New York and the New 
England States, and is largely used as a building-stone. It 
is also very common in Kansas and other of the Western 
States. Dolomite is a good building-stone where anthracite 
coal is the fuel, but in cities where bituminous coal is the 
fuel the greater amount of sulphur present in the coal is 
found to result very injuriously to the stone. This stone 
was selected for the new Houses of Parliament in London, 
after the old ones were destroyed by fire in 1838. The 
effects of the bituminous fuel in London have rendered it 
necessary to protect the buildings by artificial preparations 
such as soluble glass, etc. Some of the dolomites, such as 
the Sing Sing marble, by cautious reduction, reducing the 
magnesian carbonate with perhaps some (but not all) of the 
calcium carbonate, gives a lime possessing hydraulic prop- 
erties. 



74 DESCRIPTIVE MINERALOGY. 



Witherite, BaCO,. 

Orthorhombic. Crystals nearly hexagonal in form, like 
modified hexagonal pyramids, but composed of repeated 
twins, as shown by their optical properties, often in com- 
pact aggregates of columnar or granular texture. 

Witherite is a barium carbonate. Its color is white 
through gray to yellowish ; luster vitreous or slightly resin- 
ous ; streak white ; brittle. H. = 3 to 3.7. G. = 4.25 to 4.35. 
When heated in forceps gives yellowish-green color to flame 
and melts to a clear glass, opaque on cooling. Acted upon 
by hydrochloric acid, effervesces less violently than calcite ; 
the solution gives white precipitate with sulphuric acid, 
insoluble in acids. 

Witherite is used considerably in glass manufacture, and 
the artificial carbonate is used as a poison. 

Quartz, Silica, SiO a . 

Hexagonal. Common form, the hexagonal prism with 
corresponding pyramidal ends. Granular, cryptocrystal- 
line and compact. 

Quartz occurs under a great variety of forms, but certain 
properties are common to them all. H. = j. G. = 2.5 to 2.8. 
Alone it is infusible before the blowpipe, but when heated 
with sodium carbonate it fuses with effervescence, due to 
the escape of carbon dioxide. It is not acted upon by the 
common acids and shows no cleavage. Quartz may be con- 
veniently divided into two series, the distinctly crystalline 
or vitreous series and the cryptocrystalline or chalcedonic 
series. Some of the more important varieties of each series 
will be briefly described. 

Crystalline or Vitreous Series. 

The vitreous series have glassy luster and fracture and 
include : 

Rock Crystal. Which is pure quartz, colorless, and trans- 



SILICA. 75 

parent. It is used in jewelry under the name of white- 
stone and occidental diamond. 

Amethyst. Has a purple or bluish-violet color; perfect 
specimens are highly prized. Color supposed due to 
manganese. 

Rose Quartz. Has rose color, which becomes paler after 
long exposure to light. Usually occurs massive, slightly 
transparent. Color probably due to titanic acid and 
manganese. 

Smoky Quartz, Cairngorm. Of a smoky or brownish-black 
tint, believed to be due to organic matter. 

Milky Quartz. Of a milky color and sometimes a slightly 
greasy luster, usually massive and almost opaque. 

Cat's-eye. A gray or greenish variety, presenting opa- 
lescence when cut in convex form. Appearance due to 
penetrating asbestos. 

Aventurine. Aventurine is a form of quartz with glisten- 
ing spangles, due to the presence of scales of mica, iron 
oxide, or other mineral. The basic color is usually red or 
brown. The aventurine is frequently imitated in glass, but 
such imitations can be detected by the inferior hardness. 

There are several other varieties of vitreous quartz. 
Some authors describe all the vitreous varieties as rock 
crystal more or less pure. 

Cryptocrystalline or Chalcedonic Series. 

Chalcedony. Waxy or horn-like in appearance ; varies 
much in color, generally translucent ; frequently shows its 
origin by deposition from siliceous waters ; occurs as sta- 
lactites, lining cavities, and as incrustations. 

Agate. A mottled or cloudy chalcedony with different 
colored layers made by successive depositions. When a 
section is made across the layers the colored edges are 
shown in more or less regular lines or bands. If the layers 
are very irregular the section shows zigzag lines and the 
stone is called fortification agate. 

An agate containing moss-like or dendritic forms is called 



76 DESCRIPTIVE MINERALOGY. 

moss-agate. The colored layers are believed due partly to- 
organic matter, partly to metallic oxides (Fe and Mn), and 
largely to rate of deposition. The colors of agates may be 
changed artificially, and this is sometimes done in agates cut 
for ornaments. 

Onyx. An agate with plane layers ; these render it suited 
for cutting into cameos. If the layers are alternately white 
and sard, the stone is a sardonyx. 

Carnelian. A light red chalcedony. 

Sard. A deep red or brownish-red chalcedony, espe- 
cially by transmitted light. 

Chrysoprase. An apple-green chalcedony, colored by 
nickel oxide. 

Flint. A compact chalcedony usually dark brown or 
gray. It occurs in great abundance in nodular forms in 
the chalk-beds. It has conchoidal fracture and leaves sharp 
edges in breaking. 

Jasper. An impure opaque chalcedony, color some shade 
of yellow, red, brown, or black. Occasionally gray or green. 
If in striped bands of such colors, it is called ribbon or riband 
jasper. 

Heliotrope or Bloodstone. With green color and spots 
of red ; the green color is due to some chlorite, and the red 
to iron oxide. All the above varieties of quartz are suscept- 
ible of polish and are used as gems or in ornamental work. 

Granular Quartz. In addition to the above varieties 
many rocks consist of silica nearly pure, or quartz grains 
firmly cemented together ; such are quartzite and quartz 
sandstone. Buhrstone is a cellular quartz rock having much 
the appearance of coarse chalcedony. 

Silica is the most common petrifying material. It some- 
times replaces calcite and fluorite in their crystalline forms, 
thus giving pseudomorphous quartz. Silica is the common 
petrifying agent of shells and wood. Silicified wood is 
found in great abundance in Arizona, Wyoming (National 
Park), Colorado, and other Western States. The petrified 
forests of Arizona and Wyoming are very extensive ; the 



SILICA. 77 

first named have furnished specimens of agatized wood of 
unsurpassed beauty. 



Tridymite. 

Hexagonal. This mineral is a variety of silica whose 
crystalline form belongs to the hexagonal system, but it usu- 
ally occurs in minute, thin tabular forms. The crystals are 
generally minute and six-sided, often in twins or fan-shaped 
groups. Its properties are the same as quartz except that 
it is completely soluble in a boiling solution of sodium car- 
bonate. It occurs chiefly filling cavities in acidic volcanic 
rocks, often associated with sanidin, hornblende, or augite, 
and sometimes opal. G. = 2.28 to 2.33. 



Opal 

is an amorphous form of silica containing from three to 
thirteen per cent of water. There are several varieties 
differing widely in color. Opal is slightly less hard and 
heavy than common quartz, has a glistening, resinous lus- 
ter, and dissolves entirely in heated solution of potash ; 
frequently decrepitates when heated. The finest specimens 
give beautiful internal rainbow-reflections as the stone is 
turned in the light. 

The luster and the evident amorphous texture usually 
sufficiently distinguish opal. Like other silica it is fre- 
quently a petrifying material. 

Fiorite, Siliceous Sinter.- These terms include the siliceous 
incrustations from hot springs ; they are usually more or 
less porous, sometimes almost fibrous. 

Geyser ite. Includes the concretionary siliceous deposits 
from geysers ; these deposits are very varied in shape, and 
occur in great beauty and abundance in the Yellowstone 
Park. The terms fiorite, geyserite, and siliceous sinter are 
very often used synonymously. 

Tripolite, or Infusorial Earth is another form of opal re- 
sulting from the accumulation of diatom shells and the 



DESCRIPTIVE MINERALOGY. 



spicules of sponges. The polishing powder known as 
Electro- silicon is composed of this material. 



SILICATES. 

Silica is the abundant acid oxide of the earth's crust, and 
forms silicates with various metallic bases. The silicates are 
the most impotant rock-making minerals. 

An entirely satisfactory classification of the silicates, 
based upon their composition, has not been accomplished, 
as the definite constitution of the acids from which the sili- 
cates result is not known. 

The ordinary classification of the silicates is based upon 
what appears to be the ratio between the oxygen in the basic 
and acid anhydride parts of the silicate. The principle of this 
classification is readily seen when the formulae of the sili- 
cates are written after the dualistic method so as to show 
this oxygen relation. Thus representing by R a dyad me- 
tallic element, in the following table are written the gen- 
eral formulae of the silicates named, with the formulae of 
the acids from which they are supposed to be formed : 



. . Add. 

Orthosilicate ........ R 2 O 2 .SiO 2 I to i SiO 4 H 2 = SiO 2 .2H 2 O Orthosilicic 

Unisilicates (Dana) 

Metasilicate ......... RO.SiO 2 ito2 SiO,H 2 =SiO 2 .H 2 O Metasilicic 

Bisilicates (Dana) 

Trisilicate ........... 2RO.3SiO a 1103 Si 3 O 8 H 4 = 3SiO 2 2H 8 O Trisilicic 

Disilicate ............ RO.2SiO, 1104 Si,OH 2 = 2SiO 2 .H 2 O Disilicic 

There are many species in which the oxygen ratio is less 
than i : i, as 3 14, 2 : 3. Such species are called subsilicates, 
and it is evident that they contain a larger proportion of the 
basic radicle than the examples given in the table. In addi- 
tion it is thought probable that there are other silicic acids 
from which natural silicates may result. Neither can a dis- 
tinct line of demarcation be drawn between hydrous and 
anhvdrous silicates. 



SILICA TES. 79 

The majority of the silicates come under the head of 
metasilicates or orthosilicates, and are considered as derived 
from the corresponding- acids, SiO,H 2 , metasilicic acid, and 
SiO 4 H 4 , orthosilicic acid. The normal orthosilicates would 
then be represented by R 3 SiO 4 or R 2 O 2 SiO a , and the normal 
metasilicate by RSiO 3 or ROSIO,, in which R represents a 
dyad metal. When a greater proportion of the acid or 
basic radical is contained than the formulae indicate there 
result respectively polysilicates or subsilicates. The group- 
ing here adopted for the principal silicates is mainly in. 
tended to emphasize and fix in mind their relationship and 
importance as rock-forming minerals. 



PYROXENE AND AMPHIBOLE GROUPS. 

The members of these groups are silicates of various 
bases, among which generally appear calcium, magnesium, 
andiron; manganese, zinc, potassium, and sodium less often, 
and aluminum still more rarely. More than one base is usu- 
ally present, though some members of the group contain but 
one. The two groups are closely related in composition 
and crystalline form. Each group shows forms belonging 
to different systems of crystallization, either orthorhombic, 
monoclinic, or triclinic. The monoclinic species are most 
important, the triclinic least important. The amphibole 
group has prismatic cleavage of 124 30' and 55 30', while 
that of the pyroxene group is nearly 90. This cleavage 
angle taken in connection with the build of the crystal 
establishes the chief distinction between the groups. With 
pyroxene the distinct crystals are usually short prisms, 
often complex, in massive specimens lamellar or granular ; 
with amphibole the distinct crystals are long prisms 
and simple, in massive kinds columnar and fibrous. Only 
the more important species of each group are here de- 
scribed. 



O DESCRIPTIVE MINERALOGY. 

(A) Pyroxene Division, 
(i) Mono clinic Section. Pyroxene. 

Distinct crystals usually in short stout prisms, often 
complex, massive, granular or lamellar, sometimes fibrous 
or compact. The more important varieties of this species 
are silicates of two or more of the bases calcium, mag- 
nesium, and iron, calcium being always present, with either 
iron or magnesium or both ; aluminum in certain cases. 
The color is usually some shade of green, brown, or black; 
also occurs white. Luster varies from dull vitreous through 
imperfectly resinous to slightly pearly. H. = 5 to 6. The 
rectangular cleavage when evident distinguishes it from 
amphibole. The more important varieties are : 

Augite. This is a very abundant and important mineral, 
and is a silicate of calcium, magnesium, iron, and aluminum. 
It is black or greenish black in color and opaque. It is the 
common form of pyroxene in the basic eruptive rocks. The 
term augite is sometimes used synonymously with pyroxene, 
but more generally it is limited to the variety just 
described. 

Diallage is a thinly foliated or lamellar variety of augite. 

Malacolite. This is sometimes called white augite, and 
is a calcium-magnesium pyroxene. The granular form is 
frequently called white coccolite, from coccos, a grain. The 
green granular form, green coccolite, contains calcium and 
iron. 

The varieties of the pyroxene species are very important 
rock-making minerals. 

(2) Orthorhombic Section. 

The orthorhombic pyroxenes are magnesium, or iron 
and magnesium, silicates. The species of the pyroxene 
group under this section are : 

Enstatite. Which contains the smaller proportion of iron 
oxide not over five per cent and sometimes iron is 
absent. The color varies from grayish, yellowish, or 



SILICATES. 8 1 

greenish white to brown. Luster vitreous to pearly. 
H. = 5.5. G. = 3.1 to 3.3. It is infusible and not attacked by 
acids ; strongly resembles the monoclinic pyroxenes. 

Enstatite in a very pure state is a frequent constituent 
of meteorites. 

Bronzite. This contains more iron than the preceding 
and its color deepens from grayish yellow-green to olive- 
green. The amount of iron oxide generally ranges from 
5 to 14 per cent ; with a greater per cent of iron the bronz- 
ite passes to the next variety. 

Hypersthene. This mineral contains more iron than 
either of the preceding, the amount of iron oxide varying 
from 14 to 30 per cent. Color is a dark greenish brown or 
black, sometimes approaching a copper-red. Streak gray 
or brownish gray. H. = 5 to 6. G. = 3.4 to 3.5. 

Hypersthene often has a characteristic iridescence due 
to minute, interspersed foreign crystals, symmetrically ar- 
ranged. B.B. it fuses to a black enamel, and on charcoal 
yields a magnetic mass. This species is a common constit- 
uent of certain of the eruptive rocks. 



,y ^y^^ 

(i) Monoclinic Section. Amphibole. 

The species of the amphibole group form a series closely 
related to those of the pyroxene group ; the general dis- 
tinction between the two groups has already been indicated. 
The amphibole species of this group are analogous to the 
pyroxene species of the pyroxene group, being silicates of 
the same bases, though potassium and sodium are more 
frequently present. 

Amphibole usually occurs in columns less stout than 
those of pyroxene, often in bladed crystals, also fibrous and 
granular; the cleavage more oblique than that of pyroxene. 
The color of the amphibole varies from black to white 
through many shades of green ; streak lighter than color. 
Luster vitreous to pearly on fresh surfaces, fibrous varieties 



82 DESCRIPTIVE MINERALOGY. 

often silky. H. = 5 to 6. G. = 2.9 to 3.4. The principal 
varieties of this species are : 

Tremolite. A white lime-magnesia amphibole. It usually 
occurs as blades or needles penetrating the gangue with 
which they are associated, sometimes radiated or aggregated 
into columnar masses of silky luster. Tremolite most 
often occurs with dolomite. 

Actinolite. Of the same composition as tremolite with 
iron in addition, and occurring in the same way as aggrega- 
tions of needles or blades or in radiating forms. It usually 
occurs with serpentine. 

Asbestus. Both varieties of amphibole pass into asbestus. 
Asbestus includes the finely fibrous forms, fibers easily 
separable and resembling flax ; when the fibers are more 
like silk it is called amianthus. When the fibers adhere 
closely and the stone resembles petrified wood, it is called 
ligniform asbestus. When the fibers are interlaced so as to- 
make tough sheets, it is called mountain leather. 

Asbestus is the only variety of the amphibole species 
used in the arts. It is sometimes woven into lamp-wicks^ 
fire-proof cloths, etc. It is incombustible, and articles made 
of it may be cleansed by throwing them into fire. Asbestus 
is found at many localities in the United States, but generally 
of inferior quality and only adapted for grinding, and use 
for paints, cements, boiler and steam-pipe coverings, safe- 
linings, etc. The greater portion of the mineral called as- 
bestus, suitable for weaving into cloth is a variety of serpen- 
tine and does not fall under this species. Canada supplies, 
this serpentine form in large quantity. 

Crocidolite. This species of the amphibole group is a 
silicate of iron and sodium. It occurs asbestiform, also- 
massive and earthy. The color is lavender-blue or light 
green. Luster silky or satin to dull. H. 4. G. = 3. 2 to 3. 3. 
In closed tube gives a little water which is slightly alkaline. 
B.B. fuses easily with intumescence to a black magnetic glass 
coloring flame yellow. 

An altered form of this mineral is found abundantly in 
South Africa and popularly called " tiger-eye " or " cat's- 



SILICA TES. 83 

eye." The alteration is due to the oxidation of the iron and 
infiltration of silica. The altered mineral has a delicate but 
distinct fibrous texture and chatoyant luster, with amber- 
yellow to brown color. This form of the mineral has come 
into frequent use as an ornamental stone. 

Hornblende. This term is often used as synonymous with 
amphibole, but it is more generally applied to the dark- 
colored varieties containing a larger per cent of iron ; it 
occurs in dark green or black crystals, massive and com- 
pact. Hornblende, like pyroxene, is an important rock- 
making mineral. It is an essential constituent of the 
plutonic rocks. Such difference as exists between horn- 
blende and pyroxene is probably mainly due to the different 
conditions under which they were formed, the composition 
being substantially the same. 

Chrysolite, Olivine, Peridot. 

Chrysolite is the most important species of a group 
of silicates of the same name. It is an iron and magnesium 
silicate, color usually olive-green, but has different shades 
passing to a yellowish brown or red ; streak uncolored, 
sometimes yellowish or brownish. Hardness is about the 
same as quartz. 

Olivine is the most common variety of chrysolite ; it has 
a dark olive-green or yellow-green color. It occurs very 
generally disseminated through basaltic rock, sometimes in 
masses. 

Beryl, Emerald. 

Hexagonal. Prevailing form hexagonal prism, sometimes 
massive. 

Beryl is essentially a silicate of aluminum and beryllium 
(glucinum). There are several varieties of this mineral ; 
some are pellucid, but they are generally some shade of 
yellow, green, or blue. Luster vitreous to resinous, streak 
uncolored. H. =7.5 to 8. G.= 2.67 to 2.76. Infusible, though 
it changes color under the blowpipe. The common vari- 



84 DESCRIPTIVE MINERALOGY. 

eties with less delicate shades of color are all included 
under the name of Beryl simply ; color supposed to be due 
to iron oxide. Emerald is of a rich green color ; it contains 
a small per cent of chromium oxide, to which its color is 
generally ascribed. Aquamarine includes the transparent 
forms of very delicate shades of green or blue. 

Fine specimens of beryl come from Siberia, Ceylon, 
Colombia, and Brazil ; they have also been found at many 
places in the United States in Maine, New Hampshire, and 
North Carolina, and several of the Western States. Very 
large ones have been obtained in the two States first named. 
Beryl in color and form often resembles apatite, but is much 
harder. 

Garnet. 

Isometric. Prevailing forms are the dodecahedron and 
trapezohedron. Also occurs massive and granular. 

Garnet is a cornplex silicate which may contain two or 
more of the metals calcium, magnesium, aluminum, iron, 
and chromium, the varieties being due to the different pro- 
portions of these elements. Garnets vary much in color. 
Luster vitreous to resinous. H.=6.$ to 7.5. G. = 3.i to 4.3. 
The darker varieties may be fused without difficulty. The 
more important and common forms are the following : 

Almandite, or Almandine. Various shades of light red to 
brown. Those with clear color and considerable transpar- 
ency are the precious garnets. Almandite is an iron-alumina 
garnet. 

Essonite, or Cinnamon-stone. An alumina-lime garnet of a 
cinnamon color. 

Pyrope. An alumina-magnesia garnet of a deeper red 
color than almandine, sometimes almost black. It is also 
called precious garnet when it is fairly transparent and has a 
pure color. Pyrope is frequently found in small rounded 
masses and grains. 

Colophonite. A lime-iron garnet, consisting of a mass of 
grains of a brownish-red to brownish-yellow color ; has 
resinous luster and generally gives iridescence when turned 
in the light. 



SILICATES. 85 

The different forms of garnet often occur disseminated 
through metamorphic rocks; are found in the gneiss rocks 
about West Point. In this class of rocks the garnets are 
usually almandine. The fine red garnets constitute the 
carbuncle of the ancients. 

Garnets are found at many places. Ceylon is noted for 
its red garnets, but the richest gems come from Burmah. 
Garnets are found at many places in the United States. 
Fine specimens of pyrope abound in Arizona, New Mexico, 
Colorado, and other Western States, and are the so-called 
Arizona rubies. 

Lapis Lazuli. 

Isometric. Usually massive. This mineral is a com- 
plex silicate of aluminum and sodium and contains copper, 
iron, snlphur, and chlorine. It has an azure-blue color and 
vitreous luster. Its color is thought to be due to sodium 
sulphide. When powdered it is dissolved by hydrochloric 
acid with separation of gelatinous silica. The finest speci- 
mens are much esteemed for making ornaments and for 
inlaid work. The powdered mineral was formerly used as a 
paint under the name of ultramarine ; this color is now pre- 
pared artificially, and is very much cheaper than the natural 
paint. 

Mica. 

This term embraces a group of minerals which are 
essentially hydrous silicates of aluminum and an alkali 
metal. Potassium is the alkali metal most abundantly and 
commonly present. Sodium is often present, and in one 
variety it entirely replaces the potassium. The next most 
important constituents are lithium, iron, and magnesium, 
the last-named metal being so abundant in some varieties, 
that they are sometimes called magnesian micas; in these,, 
however, potassium is present. Most of the micas contain 
fluorine. The formulas for the different varieties of mica, 
have not been precisely determined. 

The micas belong to the monoclinic system and are,- 



86 DESCRIPTIVE MINERALOGY. 

characterized by a highly laminated structure and perfect 
cleavage. The laminae are flexible and elastic. 

Muscovite is one of the common micas, being a hydrous 
silicate of aluminum, potassium, and iron. It has white or 
silvery color, passing to various shades of yellow, brown, 
and green. H. = 2 to 2.5. It is a common constituent of 
granite, gneiss, and mica schist, and in these rocks usually 
occurs in minute silvery scales. 

Lepidolite is muscovite containing a little lithium, which 
gives it a delicate lilac or rose-colored shade found only in 
this variety. 

Biotite. Like muscovite, a hydrous silicate of aluminum, 
potassium, and iron, but in addition containing a large per 
cent of magnesium. It is generally greenish black to black 
in color. It is even more common in the granitic arid met- 
amorphic rocks. 

Mica, in the clear transparent forms, has long been used 
for furnace and stove doors and lamp-protectors. It is now 
very largely used as an insulator in the construction of 
dynamo machines. For this purpose the color is imma- 
terial, but perfect cleavage is necessary, as the plates must 
be of uniform thickness and often very thin. For insulating 
purposes small laminae can be fastened together by suitable 
mucilage so as to form large sheets. Mica is also ground 
up and used for mural painting and in the manufacture of 
wall-paper. It can thus be made to produce a metallic, 
frosted, or spangled surface. The ground mica is also used 
as an absorbent of nitroglycerin in certain mica powders. 
For grinding, waste mica is generally used. Mica is chiefly 
mined in this country in New Hampshire, North Carolina, 
and South Dakota. Most of that now used in this country 
is imported from India and Canada, though this will proba- 
bly not be long done. 

FELDSPAR. 

The feldspars are essentially silicates of aluminum, potas- 
sium, sodium, and calcium. They all contain aluminum, the 
other metals alternating in the different species. The com- 



SILICA TES. 87 

mon and important forms of feldspar all belong- to the tri- 
clinic system, except orthoclase, which is monoclinic. The 
group has a hardness of from 6 to 7, and a specific gravity 
of from 2.4 to 2.7. 



Orthoclase, Common Feldspar, Potash Feldspar. 

Monoclinic. Prevailing forms, oblique prisms or deriva- 
tives. Also massive, with lamellar or granular texture. 
Sometimes finely compact. 

A silicate of aluminum and potassium containing a 
little sodium. Generally light or flesh color, though dark 
colors are not uncommon, and there are various intermedi- 
ate shades. It is similar in other respects to albite, except 
that it has two cleavage planes at right angles to each other, 
which, when evident, is sufficient to distinguish it from that 
form. It is a common constituent of many of the igneous 
and metamorphic rocks ; abundant in the gneiss about West 
Point. Ground orthoclase is extensively used' as a glaze 
and flux in the manufacture of pottery. 

Sanidin. Is a transparent and glassy form of orthoclase, 
frequently in crystals imbedded in lava. 

Adularia.\s a white, clear orthoclase, often with pearly 
opalescence. 

Albite, Soda Feldspar. 

Triclinic. Usually in crystalline masses with more or 
less lamellar structure. 

In composition a silicate of aluminum and sodium ; color 
generally white or gray, often of shades of blue, red, or 
green ; subtranslucent. Is not acted upon by acids ; fuses 
with difficulty and colors flame yellow. 

Albite is a constituent of many crystalline rocks, such as 
diorite, granite, and gneiss. The finest crystalline specimens 
occur in granite veins. Albite frequently shows fine striae 
on cleavage surfaces due to intersection of faces of crystal- 
line laminae. 



88 DESCRIPTIVE MINERALOGY. 



Microcline. 

This species is in composition nearly the same as ortho- 
clase, but more generally contains sodium. It is, however,, 
triclinic, though the cleavage angle varies but slightly from 
a right angle. 

There are many other varieties of feldspar, the more im- 
portant of which are Anorthite, Labradorite, Andesite, and 
Oligoclase. The first named is a calcium feldspar, and the 
others are calcium and sodium feldspars. Anorthite and 
Labradorite are sometimes called basic feldspars because 
they contain less than 60 per cent of silica ; the others are 
termed acid feldspars. Plagioclase is a general term often 
used to include all the triclinic feldspars except microcline. 
The feldspar species is one of the most important rock-mak- 
ing minerals. 

FELSPATHOID GROUP. 

This group includes several silicates of aluminum and an 
alkali metal, and in this respect is closely related to the feld- 
spars. The group, however, have different crystalline forms 
and physical properties, and in the arrangement of the sili- 
cates already referred to they do not fall in the same class. 
as the feldspars. The more important species of the fel- 
spathoid group are given below. 



Leucite, Amphigene. 

Isometric. Leucite generally occurs in crystals, grains, or 
granular masses. The larger crystals often show inclusions 
of foreign matter symmetrically arranged. 

Leucite is a silicate of aluminum and potassium, the lat- 
ter being sometimes replaced in small quantity by sodium. 
Color usually dull white to dark gray ; streak white. H. = 
5.5 to 6. G. = 2.4 to 2.5. Brittle with conchoidal fracture.. 
B.B. infusible, blue color with cobalt solution by ignition. 

Generally found in recent eruptive rocks. 



ft^ir 

SILICATES. 89- 



Nephelite, Nepheline. 

Hexagonal. Occurs in white columnar crystals, six- or 
twelve-sided, also in granular masses and compact. 

Nephelite is a silicate of potassium and sodium ; its color 
is white or yellowish, massive varieties dark green, bluish 
gray, brown or red ; luster vitreous to greasy. H. = 5.5 to 6. 
G. = 2.55 to 2.65. Brittle, with semi-conchoidal fracture. 
B.B. fuses to a colorless glass; gelatinizes with acids. 

Nepljelite occurs in both recent and ancient lavas, also 
in certain plutonic rocks. 

Analcite, Analcine. 

Isometric. Occurs in trapezohedra, also massive and 
granular ; cleavage cubical but imperfect. 

Analcite is a hydrous silicate of aluminum and sodium. 
Color is white, sometimes shaded gray, green, yellow, or 
red ; luster vitreous. H. = 5 to 5.5. G. = 2.2. Brittle, with 
semi-conchoidal fracture. Gives water in closed tube. 
B.B. fuses without difficulty to a colorless glass. Gelatinizes 
with hydrochloric acid. 

Analcite is of frequent occurrence in cavities and seams 
in basic volcanic rocks, also in granite and gneiss. 

Of the species here included in the felspathoid group, 
leucite and nephelite are richer in alkali than the feldspars, 
and analcite is a hydrous silicate. 

Topaz. 

Orthorhombic. Crystals commonly prismatic, generally 
differently modified at the two extremities, faces usually 
striated vertically ; also massive in columnar aggregates, 
coarse or fine granular. Perfect cleavage parallel to base. 

Topaz is a silicate of aluminum with part of the oxygen 
replaced by fluorine; also frequently contains hydroxyl. 
Its color varies from yellow, through gray and white to 
shades of green, blue, or red ; luster vitreous ; streak white ; 



pO DESCRIPTIVE MINERALOGY. 

brittle. H. = 8. G. = 3.4103.6. B.B. infusible ; not affected 
by acids, except partially by H 2 SO 4 . Distinguished by its 
hardness, infusibility, brilliant and easy basic cleavage. 

Topaz most generally occurs in the acidic igneous rocks, 
as granite and rhyolite ; also in metamorphic schists. It is 
frequently accompanied by fluorite, tourmaline, beryl, and 
apatite. The transparent and colorless varieties are used 
as gems, the pink crystals being most valuable. 



Andalusite. 

Orthorhombic. Crystals generally nearly square prisms, 
massive and indistinctly columnar, occasionally radiated and 
granular. 

Andalusite is a silicate of aluminum ; some of the alumi- 
num is often replaced by iron. Color white, pearl-gray, 
pink to brownish red and olive-green; luster vitreous; 
streak uncolored; brittle. H. = 7.5. G. = 3. i to 3.2. B.B. 
infusible ; not affected by acids. Heated with cobalt solu- 
tion gives a blue color. 

Occurs only as imbedded crystals, most commonly in 
schists. 

Kaolinite. 

Kaolinite is a hydrous silicate of aluminum resulting 
mainly from the decomposition of the feldspars. In the 
course of time rocks containing these minerals, such as 
granite, gneiss, etc., are disintegrated by aqueous and 
atmospheric agencies, the disintegration being due to the 
decomposition of the feldspars. 

The feldspars in passing to kaolinite lose their alkaline 
and lime bases and part of their silica and take up water. 
It is thought that the carbon dioxide of the atmosphere and 
other organic acids are the essential agents in removing the 
bases from the minerals. With the change in the feldspar, 
the rock crumbles, and both the kaolinite and the associated 
constituents are eroded and carried away by the running 
waters and eventually deposited. 



SILICATES. 91 

Kaolinite is ordinarily called kaolin. When pure it has 
a soapy feel, white color, and when touched to the tongue 
adheres strongly. When breathed upon it gives the well- 
known clay odor, it is infusible, not acted upon by acids 
under ordinary conditions, and yields water when heated in 
a closed tube. 

Common clays contain more or less kaolinite mingled 
with eroded material from the parent rock and from the 
rocks over which the depositing waters have passed. The 
minerals most frequently mingled with the kaolinite are 
finely divided quartz, feldspar, and mica. 

Common clays usually contain some of the compounds of 
iron, and if these are of such nature as not to withstand heat, 
the clay will generally burn red, due to the transformation 
of the iron compound into the red oxide. The ordinary 
alterable iron compounds in clay are the limonite, carbon- 
ate, or perhaps iron, combined with some organic acid. If 
the iron be in some of the silicated forms, the clay does not 
change color by heat. The well-known cream-colored 
Milwaukee bricks are made of such clay. 

The use of clay in brick-making is well known. If of 
good clay, brick is one of the best building-stones to resist 
heat. Porcelain is made of the purest kaolin, stoneware of 
the less pure varieties. Fire-bricks are generally made of a 
fine quality of clay, though they are sometimes composed 
of a large per cent of silica. 

Tourmaline. 

Hexagonal. Prism the prevailing form, with three (or 
some multiple of three) sides. Sides usually striated or 
channeled. Ends of crystals frequently unlike. Also 
occurs massive. 

Tourmaline is a complex silicate, essentially of aluminum 
and boron, but with several other bases, the proportions of 
which are believed to give the many different varieties. 

The common forms are usually brown or some shade of 
black, but there are various shades of red, yellow, and 



92 DESCRIPTIVE MINERALOGY. 

green. Generally translucent to opaque. H. = 7.5. It is 
brittle, fractured surface uneven. Tourmaline when in 
crystals is distinguished by the number of faces being some 
multiple of three. Its hardness is usually sufficient to dis- 
tinguish the dark varieties from resembling minerals. 

Rubellite is the red tourmaline. 

Indicolite is the blue tourmaline. 

Tourmaline is also found in white, blue, and green colors. 

This mineral usually occurs penetrating crystalline rocks; 
it is not an essential constituent. The fine specimens are 
highly prized as gems. 

Specimens that rival any in the world in beauty have 
been found in Maine, at Paris and Hebron. Fairly fine 
specimens have been found in many other States of the 
Union. Ceylon and Brazil have also given celebrated 
crystals. 

Talc. 

Talc is a hydrous silicate of magnesium and nearly 
always contains a little iron. Generally occurs in foliated 
masses with a pearly luster, readily peeling off in layers ; 
masses also compact and of fine scales, occasionally granular 
and less often fibrous. Talc is usually of a greenish- white 
color, but varies to other shades of green and to nearly pure 
white. In the laminated variety H. = i to 1.5. The scales 
are flexible but not elastic. Yields water with difficulty 
when heated in closed tube. Infusible and not acted upon 
by acids. All varieties have a greasy feel. 

There is a number of varieties of this mineral, of which 
the more important will be mentioned. 

Talc. This term is commonly limited to the more dis- 
tinctly foliated varieties. 

Steatite, Soapstone. Fairly compact or finely granular in 
texture, usually greenish gray or gray. 

French Chalk. The white laminated variety, used for 
marking on cloth. 

Indurated Talc. An impure variety of a somewhat shaly 
texture, with hardness of 3 to 4. 



SILICA TES. 93 

Talc occurs in many of the States and in Canada. Penn- 
sylvania furnishes the greater quantity of the steatite, 
though it is also mined in Virginia, North Carolina, and 
South Carolina. It is trimmed into slabs for various uses 
as bath-tubs, laundry -tubs,, frames to hot-air registers, etc. 
In the powdered form it is largely employed as a filler in 
mineral paints and in fire-retarding paints. Fibrous talc is 
extensively mined at Gouverneur, N. Y., and is largely used 
to give weight and filling in the manufacture of paper. 
This form passes under the name of mineral pulp. The 
powdered form is also used as a lubricant for machinery and 
for diminishing machinery friction generally. Boot-powder 
is composed of it. 

Serpentine. 

This mineral, like talc, is also a hydrous silicate of 
magnesium, but contains more water and less silica than 
talc. It generally occurs massive and compact and finely 
fibrous. Color is usually some shade of green, more often 
green tinged with yellow, though sometimes nearly white. 
Luster faintly resinous to oily. H. = 2.5 to 4; often has 
greasy feel, but less so than talc. Yields water readily 
when heated in closed tube, and changes color to brown. 

Precious Serpentine. When the color is a bright tint of 
yellow-green and the mineral translucent. When the 
mineral is opaque and the color dull it is common serpentine. 

Chrysotile. This is the finely fibrous variety and is largely 
used under the name of asbestus. This is the mineral that 
is, in this country, generally woven into fire-proof roofing, 
clothes, etc. It is obtained in New York, but much more 
abundantly in Canada, being called asbestus. 

Verd Antique, Ophiolite. This name is applied to a 
mineral composed of a mixture of serpentine and lime- 
stone. When polished it gives a marble, mottled, and often 
of much beauty. Serpentine itself gives a marble, but 
generally not so variegated as when calcite is present. 
Pennsylvania furnishes a serpentine which is used as a 
building-stone. 



94 DESCRIPTIVE MINERALOGY, 

Chlorite. 

Chlorite is a general term applied to a group of minerals 
which are hydrous silicates of magnesium and aluminum, 
and in which iron and other metals are usually present in 
small quantity ; less silica is present than in serpentine. 
The term chlorite is also applied to the more important 
varieties of this group, which are of extensive occurrence, 
but whose compositions are not well determined and whose 
forms are not distinctly defined. The distinctly crystallized 
species are not of great importance. When the word is 
used in the limited sense it refers to the dark green varieties 
which occur foliated and massive and also in fine granular, 
almost compact forms and finely fibrous. H. = i to 2. 
Streak is whitish or slightly greenish, yields water in closed 
tube. Color due to the large per cent of iron present. 

MINERAL COAL. 

This important substance is essentially composed of car- 
bon, hydrogen, oxygen, a little nitrogen, and sulphur, to- 
gether with some earthy matter which gives the ash. There 
may also be a little moisture present and sometimes oc- 
cluded hydrocarbons, but these are accidents in the coal. 
Coal occurs massive and uncrystallized, is from brown to 
black in color. H. = 1.5 to 2.5. 

Perfect coal when pure may be divided into two general 
classes, Anthracite and Bituminous, depending upon the 
per cent of volatile ingredients present. 

Anthracite. This coal has a high luster, between vitre- 
ous and metallic, color glistening-black, often iridescent. 
H. =: 2 to 2.5. G. about 1.6. Often gives conchoidal frac- 
ture ; it burns with a pale blue flame. In this coal go to 95 
per cent of the combustible matter is fixed carbon. It con- 
tains from 5 to 12 per cent of earthy matter, which is left as 
ash in burning. The volatile matter in the coal ranges from 
three to seven per cent. It is sometimes called stone-coal or 
glance. 



MINERAL COAL. 9 

Bituminous Coal. This coal has a dull or slightly resin- 
ous luster. H. = 1.5 to 2. G. = about 1.3. It burns with a 
smoky yellow flame. 

In this coal the combustible matter contains from 45 to 
85 per cent of fixed carbon, from 15 to 55 per cent of volatile 
matter; there is present from i to 8 per cent of earthy mat- 
ter. When the combustible matter contains from 80 to 85, 
per cent of fixed carbon and 15 to 20 per cent of volatile 
matter it is called semi-bituminous. When the volatile mat- 
ter rises to 30 or 40 per cent it is full bituminous, and when 
beyond this per cent it is highly bituminous. 

Common bituminous coals are generally divided into 
two kind, caking and non-caking. Caking coal softens 
and becomes pasty in the fire, so that pieces in contact ad- 
here, forming a solid mass. Non-caking coal burns freely 
without softening. These varieties cannot be distinguished 
by external characters, nor has the chemical difference be- 
tween them been determined. 

Cannel Coal. A highly bituminous variety, of compact 
texture, with little luster, and conchoidal fracture. It burns 
brightly with much flame. It is very valuable for making 
gas as well as for open-grate burning. 

Brown Coal. An imperfectly formed coal, in which the 
conversion of the vegetable matter into coal has not beea 
completed. It contains from 15 to 35 per cent of oxygen. 
It is of a brownish-black or black color, streak brown. 
When the woody structure is still clearly visible it is called 
lignite. 

Jet. This is a very black, compact variety of brown coal. 
It takes a high polish and is used for cheap ornaments. 

In addition to these varieties a native coke has been found 
in Virginia, probably resulting from the action of eruptive 
rocks on bituminous coal. It resembles common coke, but 
is more compact. 

All the varieties of coal may contain greater or less pro- 
portions of mineral impurities, giving other divisions de- 
pending upon the degree of impurity. If the ash does not 
amount to more than 8 or 10 per cent in anthracite, the coal 



9 DESCRIPTIVE MINERALOGY. 

may be considered as pure. The pure anthracite gives 
more ash than the pure bituminous, which was to be ex- 
pected, as the former results from a condensation of the 
latter. The mineral matter making up the ash of pure coal 
comes from the plants out of which the coal was formed. 
It consists mainly of silica, alumina, oxide of iron, lime in 
small quantity, and a little potash and magnesia. 

The origin of coal and the location of the beds are given 
in Geology. 



TABLES FOR USE IN THE DETERMINATION 
OF MINERALS. 

THESE tables have been constructed with the view of 
facilitating the determination of the minerals of the text. 
The order of arrangement and the directions for use of 
the tables are intended .to develop and improve the powers 
of comparison and observation, as well as to bring about a 
correct determination of the mineral species. 

The minerals are classified under three general sub- 
divisions, A, B, and C. 

A includes all the minerals with a distinctly metallic 
luster. 

B includes all minerals that have not a distinctly metallic 
luster, but have a colored streak. 

C includes all minerals with an unmetallic luster and an 
uncolored streak. 

In the first subdivision (A) the minerals are again clas- 
sified according to color ; in the second (B) according to 
streak; and in the third (C) according to hardness; and in 
each of these smaller classes the minerals are arranged in 
the order of their hardness. 

The tables consist of two principal parts ; in the first 
are given the external characteristics of the minerals ; in 
the second are described the effects of acids and of heat. 
The former should always be examined first. Some speci- 
mens can be determined from external characteristics alone, 



TABLES fOR DETERMINATION OF MINERALS. 97 

and many others can be limited to a small number of species. 
The method of procedure in the determination of minerals 
should be as follows: 

Take up the specimen and note its luster, whether 
metallic, semimetallic, or unmetallic ; if metallic, note its 
color ; if semimetallic or unmetallic, determine its streak. 
Finally, determine the hardness of the specimen. Now try 
to place it as rapidly as possible in the table : in A by its 
color first, then by its hardness; in B by its streak first, 
then by its hardness ; in C by its hardness alone. When 
the specimen under consideration is thus approximately 
determined, see if the other characters given in its descrip- 
tion correspond to what is observed in the specimen. This 
is all that can be accomplished by the use of the first part 
of the tables ; for further verification the directions in the 
second part of the tables must be followed and the effects 
of acids and heat observed. For a proper use of the tables 
the student must be familiar with the contents of Chapter 
II, which precedes, and must; also have instruction and as- 
sistance in the use of the appliances of the mineralogicai 
laboratory. 



9 8 



A. MINERALS WITH 

EXTERNAL CHARACTERISTICS. 



No. 


Species. 


Color. 


Streak. 


Hardness and 
Tenacity. 


Remarks. 



I. BED OB BROWN. 



Copper 


Copper red 


Copper red 


H.=2.7 

Malleable 


Proustite 


Scarlet ver- 
milion 


Scarlet, ver- 
milion, 


H.=2. 5 

Brittle 






sometimes 








orange 
yellow 




Bornite 

(Erubescite) 


Brownish 
red 


Dark gray- 
ish black 


H.=3.o 
Brittle 


Cuprite 


Red to 
brown 


Brownish 
red 


H. =3.5104 
Brittle 


Rutile 


Red to 
brownish 
red 


Gray to 
yellowish 
brown 


H.=6to6.5 
Brittle 


Cassiterite 


Brown to 
reddish 
brown 


Gray to 
light 
brown 


H.=6 to 7 
Brittle 



Crystals isometric; occurs 
usually massive and in 
plates or strings penetrat- 
ing the gangue; clings to 
a file. G.>8 

Generally found with other 
ores of silver, especially 
with pyrargyrite, cerargy- 
rite, and native silver 



Color decidedly more red 
than that of chalcopyrite 



Sometimes in octahedrons, 
but often massive, gran- 
ular, and earthy; frequent- 
ly contains iron oxide^ 
G. = 5.8 to 6.1 

Distinguished from tin ore 
by not giving tin with 
soda on charcoal 

Practically the only ore ofi 
tin. G.=6.8 to 7.1* 



II. YELLOW. 



7 


Gold 


Golden yel- 


Yellow 


H. = 2. 5 


Crystals isometric, occurs 






low 




Malleable 


usually in grains, strings, 












or plates in a gangue of 












quartz, the latter being 












often discolored by iron- 












Clings to a file. G.>i$ 


8 


Chalcopyrite 


Bronze yel- 


Greenish 


H.= 4 -2 


Often tarnished and irides- 






low 


black 


Brittle 


cent, sometimes green on 












surface ; purer varieties 












have deeper color 



METALLIC LUSTER. 



99 



No. 


Composition. 


Action of Acids. 


Effects of 


Heating. 



Cu 



Ag 3 AsS 3 



Cu 3 FeS 3 



Cu 2 



TiO, 



SnOj 



Acted upon by HNOs, hy- 
drogen escaping ; addi- 
tion of ammonia to diluted 
solution gives blue color 



Acted upon by HNO 3 with 
separation of sulphur 



After careful roasting par- 
tiallyactedupon by HNO 3 , 
and addition of ammonia 
to diluted solution gives 
blue color 

Acted upon by HNOs and 
diluted solution gives blue 
color with ammonia 



No action 



Not perceptibly acted upon 
by acids 



On charcoal fuses easily 
and gives odors of sul- 
phur and arsenic oxide; 
white sublimate in open 
tube. With soda and re- 
ducing flame, bead of silver 

Fuses readily to a black 
magnetic globule 



Fuses easily in forceps and 
colors flame green; yields 
bead of copper on char- 
coal 



B. B. infusible alone 



B. B. alone infusible; with 
soda on charcoal reduced 
to metallic tin and gives 
white coating ; requires 
long blowing 



Au 



CuFeS, 



No action 



After careful roasting par- 
tiallyacted uponby HNO 3 , 
and addition of ammonia 
to diluted solution gives 
blue color 



Fuses without difficulty, 
but no action with fluxes 



Carefully roasted and' 
mixed with soda and 
heated on charcoal, gives 
a globule of copper 



100 



A. MINERALS WITH 

EXTERNAL CHARACTERISTICS. 



No. 


Species. 


Color. 


Streak. 


Hardness and 
Tenacity. 


Remarks. 



II. -YELLOW. 



9 Pyrrhotite 



10 



Pyrite 



Bronze yel- 


Grayish 


H. =3.5104 


low 


black 


Brittle 


Brass yel- 


Brownish 


H.=6 


low 


black 


Brittle 



III.-WHITE. 



12 



Silver 


Silver white 


Silver white 


H.=2. 5 

Malleable 


Arsenopyrite 

(Mispickel) 


Tin-white 
to gray- 
ish 


Grayish 
black 


H. = 5-5 
Brittle 



Usually slightly magnetic. 
Composition varies, but 
conforms to the general 
formula Fe n S n -| i 

Isometric; sometimes mas- 
sive, but generally in 
crystals disseminated 
through rocks. Sides of 
cubes often striated at 
right angles to each other. 
Harder than chalcopyrite 



Isometric; occurs in strings 
or plates disseminated 
through the gangue; 
clings to a file; generally 
tarnished on exposed sur- 
face. G. = 10.5 

Hard, strikes fire with steej 
and emits odor of garlic. 
G.=6 



IV.-GRAY. 



13 


Graphite 


Iron gray 


Black, shin- 
ing 


H. = i 

Friable 


Feels greasy, soils paper; 
micaceous or scaly, rarely 
compact. Often dissemi- 
nated through rock in fine 
scales. G. = 2.25 


14 


Molybdenite 


Lead gray, 
inclining 
to black 


Bluishgray, 
shining 


H. = i. 5 

Friable 


Feels greasy; occurs thin, 
tabular, or scaly; soils 
paper. G.>4 


15 


Stibnite 


Lead gray 


Dark gray- 
ish black 


H.=2.5 
Brittle 


Burns in flame of candle; 
slightly sectile. Princi- 
pal ore 



METALLIC LUSTER. '. ,,/*, 



I 10 1 



No. 


Composition. 


Action of Acids. 


Effects of 


Heating. 



Fe 7 S 6 



FeS 2 



Acted upon by HC1 with 
liberation of hydrogen 
sulphide 



Roasted first; slightly acted 
upon by HC1; addition of 
K 4 FeCy 6 gives blue pre- 
cipitate 



B. B. fuses easily to a black 
magnetic globule 



B. B. sulphurous odor and 
fuses to magnetic globule 



12 



Ag 



FeAsS 



Acted upon by HNO 3 ; ad- 
dition of HC1 gives a 
white curdy precipitate, 
soluble in ammonia. Cop- 
per plate placed in nitric 
solution becomes coated 
with silver 



On charcoal alliaceous 
odor, giving white coating 
on coal; leaves magnetic 
globule. In closed tube 
gives a black sublimate of 
arsenic; sometimes red 
and yellow sublimates 



No action 



MoS a Acted upon by HNO 8 , giv 

ing a grayish residue of 
molybdic oxide 



Sb-Sa When pure, acted upon by 

HC1; HNO 3 causes a sep- 
aration of sulphur and 
antimony pentoxide 



Mixed with niterand heated 
in closed tube, deflagrates 



In forceps colors flame 
green; finely powdered, 
gives sulphurous odor in 
open tube 

Fuses easily and gives 
white fumes and volatile 
white coating on charcoal 



102 



A. MINERALS WITH 



EXTERNAL CHARACTERISTICS. 



No. 


Species. 


Color. 


Streak. 


Hardness and 
Tenacity. 


Remarks. 



IV.-GBAY. 



16 



18 



21 



Argentite 


Blackish 
lead gray 


Blackish 
lead gray 


H.=2. 5 
Malleable 


Galenite 


Bluish gray 


Dark gray 


H.=2. 7 
Friable 


Chalcocite 


Blackish 
lead gray 


Dark lead 
gray to 
black 


H. =2. 5103 
Brittle 


Tetrahedrite 


Dark gray 
to black 


Dark gray 
to black, 


H.=3to 4 
Brittle 






and inclin- 








ing to red 




Tennantite 


Blackish 
lead gray 
to black 


Dark gray 
to black, 
sometimes 


H.=3to 4 
Brittle 






reddish 




Hematite 

Specular 
iron ore 


Between 
iron black 
and dark 


Cherry red, 
brownish 
red 


H.=6. 5 
'Brittle 




steel gray 







Can be cut like lead when 
massive; is usually finely 
disseminated through the 
gangue. Most common 
ore of silver. G. - 7.3 



Is chief ore of lead. Often 
has characteristic cubical 
cleavage which is easily 
obtained. Also occurs in 
granular masses; very of- 
ten contains some silver 
sulphide. The ore be- 
comes more micaceous as 
the silver sulphide in- 
creases. G. > 7 

Somewhat resembles argen- 
tite, but is not sectile 



Often a valuable ore of sil- 
ver, the copper being in 
part replaced by silver 



Closely related to tetrahe- 
drite, the antimony being 
wholly or partly replaced 
by arsenic 

Hexagonal; occurs com- 
pact, scaly, fibrous; some- 
times slightly magnetic* 
G.=4-9 t 5-3 



V. BLACK. 



22 


Graphite 


Iron black 


Black, shiny 


H. = i 
Friable 


Other characteristics the 
same as the gray variety, 
13 above 



METALLIC 






LUSTER. 









103 



No. 


Composition. 


Action 


of Acids. 


Effects of 


Heating. 



r6 



18 



Ag,S 



PbS 



Cu,S 



Cu 8 S 7 Sba 



Cu 8 S 7 As 2 



Fe,0 3 



Acted upon by HNO 3 , with 
separation of sulphur; ad- 
dition of HC1 gives a 
white curdy precipitate, 
soluble in ammonia. Cop- 
per plate placed in nitric 
solution becomes coated 
with silver 

Acted upon by HNO 3 , with 
separation of sulphur and 
formation of some lead 
sulphate; addition of am- 
monium sulphide gives 
black precipitate 



Acted upon by hot HNO 3 , 
with separation of sul- 
phur; solution coats knife 
blade with copper 

Acted upon by HNO 3 , and 
addition of ammonia to 
dilute solution gives blue 
color. (Copper test) 



Acted upon by HC1; addi- 
tion of K 4 FeCy to dilute 
solution gives blue pre- 
cipitate 



Sulphurous odor in open 
tube; fuses easily on char- 
coal and gives globule of 
silver 



On charcoal decrepitates; 
sulphurous odor; gives 
yellow coating on coal 
and yields globule of lead 



On charcoal powder gives 
sulphurous odor and 
leaves globule of copper 



Fuses easily on charcoal, 
giving sulphurous odor 
and white sublimate; a 
globule of copper after 
long heating with soda 



Infusible, but easily be- 
comes magnetic on char- 
coal 



No action 



Same as 13 above 



104 



A. MINERALS WITH 

EXTERNAL CHARACTERISTICS. 



No. 


Species. 


Color. 


Streak. 


Hardness and 
Tenacity. 


Remarks. 


V. BLACK. 


23 


Argentite 


Grayish 

black 


Gray black 


H.=2t02.5 

Malleable 


Same as 16 above 


24 


Pyrolusite 


Iron black 
to bluish 
black 


Black, blu- 
ish black, 
sometimes 
shining 


H.=2t02.5 

Brittle 


The common ore of manga- 
nese ; occurs compact to 
unconsolidated. G. 4.8 


25 


Pyrargyrite 


Black, red 
by trans- 
mitted 
light 


Purplish 
red 


H.=2to 2.5 
Brittle 


Occurs with other ores of 
silver. G. = 5.8 


26 


Stephanite 


Black to 
iron black 


Black to 
iron black 


H.=2 to 2. 5 
Brittle 


Brittle with uneven frac- 
ture. G. >6 


27 


Chalcocite 


Grayish 
black 


Grayish 
black 


H. = 2. 5 to 3 
Brittle 


Often tarnished blue or 
green. G. = 5-5 to 5.8 


28 


Melaconite 


Black to 
gray 

i 


Black 


H. = 3 to 4 
Brittle to 
earthy 


Black masses and concre- 
tions along with other 
ores of copper. G. = 5.8 
to 6.2 


29 


Chromite 


Black, iron 
black, 
brown 
black 


Yellow, 
gray or 
dark 
brown 


H. = 5 to 5. 5 
Brittle 


Generally magnetic, some- 
times strongly so. G.= 
4-3 


30 


Magnetite 


Iron black 


Black 


H. = 5.5 
Brittle 


[sometric ; granular or com- 
pact ; black streak and 
magnetic property usually 
distinguish it. G. >5 


V 


Franklinite 


Iron black 


Brownish 
black 


H. = 5.5 to 
6.5 
Brittle 


Isometric. Resembles mag- 
netite, but generally has 
more earthy black color, 
usually feebly magnetic 


32 


Hematite 


Between 
iron black 
and dark 
steel gray 


Cherry red, 
brownish 
red 


H.=6.5 
Brittle 


Hexagonal. Occurs com- 
pact, scaly, fibrous, some- 
times slightly magnetic. 
G. =4.9 to 5.3 



METALLIC LUSTER. 



ios 



No. 


Composition. 


Action of 


Acids. 


Effects of 


Heating. 



23 
24 



26 



27 



29 



Ag 2 S 
MnO a 

Ag 3 SbS< 



Ag,SbS< 



Cu 2 S 



CuO 



FeCr 2 4 



Fe,0 4 



Oxides of 
iron, zinc, 
and manga- 
nese 

Fe 3 3 



Same as 16 above 



Acted upon by HC1 with 
evolution of chlorine 



Same as 16 above 



Amethystine bead with 
borax in oxidizing flame 



Acted upon by HNOa, with On charcoal fuses easily 
separation of sulphur and with spurting, giving 
antimony oxide. Copper 
plate in nitric solution be- 



comes coated with silver 



Acted upon by HNO 8 , with 
separation of sulphur. 
Copper plate in nitric so- 
lution becomes coated 
with silver 

Same as 18 above 



Acted upon by HNOj, and 
gives copper test with am- 
monia as in 4 and 8 



Not acted upon 



Acted upon by HC1. Gives 
iron test, same as 21 above 



Acted upon by HC1 with 
occasional evolution of 
chlorine. Gives iron test 
as in 21 

Gives iron test with 
K 4 FeCy 6 , same as 21 



white coating of antimony 
oxide. With soda in re- 
ducing flame gives silver; 
red sublimate in open 
tube, white in closed 



On charcoal gives sulphur- 
ous odor; fumes and coat- 
ing of antimony. With 
soda a globule of silver 



Same as 18 above 



Gives copper with soda on 
charcoal 



Gives emerald green color 
to bead of borax and salt 
of phosphorus 



B. B. infusible 



Amethyst bead with borax, 
bluish green bead with 
soda 



Same as 21 



io6 



A. MINERALS WITH 

EXTERNAL CHARACTERISTICS. 



No. 


Species. 


Color. 


Streak. 


Hardness and 
Tenacity. 


Remarks. 


V.-BLACK, 


33 


Rutile 


Black 


Gray to 

light 
brown 


H. =6 to 6.5 
Brittle 


Distinguished from tin ore 
by not yielding tin with 
soda on charcoal. G.= 












4-2 


34 


Cassiterite 


Black 


Gray to 
light 
brown 


H=6to7 
Brittle 


Principal ore of tin. G.= 
6.8 



B. MINERALS WITHOUT 

EXTERNAL CHARACTERISTICS. 



No. 


Species. 


Luster and 
Color. 


Streak. 


Hardness and 
Tenacity. 


Remarks. 


I.-STREAK GRAY, BLACK, OB GREEN. 


35 Graphite 


L. Semi- 


Black or 


H. = i 


Luster sometimes dull or 






metallic 


dark gray 


Friable 


earthy black, other char- 






C. Iron 






acters same as 13 






black to 












dark gray 








36 


Coal 


L. Resinous 


Grayish 


H. = 2. 5 


Usually shows lamination; 




(Bitumin- 


to vitre- 


black 


Friable 


the cannel coal is compact 




ous) 


ous; some- 


Brownish 


Brittle 


with large conchoidal 






times 


black 




fractures. Decomposing 






silky 






pyrite in coal produces a 






C. Black 






gray or yellowish powder 












with inky taste. G. =1.03 


37 


Melaconite 


L. Unmetal- 


Black 


H.=2.5 


A black powder or massive 




Tenorite 


lic 




Friable 


and compact; often stained 






C. Black 






greenish; soils fingers 












when massive or pulver- 












ulent. G.>5.5 


38 


Coal 


L. Semi- 


Black 


H.=2. 7 5 


Hard, with high luster; 




(Anthracite) 


metallic; 




Very 


breaking with small con- 






vitreous 




brittle 


choidal fracture. G. = i.6 






C. Black 








39 


Amphibole 


L. Vitreous 


Dark gray 


H. = 5-6 


Monoclinic; crystals long 




(Horn- 


C. Black to 


to green- 


Tough 


and slender, cleavage ob- 




blende 


greenish 


ish gray 


Brittle 


lique, 124; massive spe- 






black 






cimens have black color, 












common luster, are often 












made up of bladed crystals 












intersecting in all direc- 












tions. G.=3.3 



METALLIC LUSTER. 



107 



No. 


Composition. 


Action of Acids. 


Effects of 


Heating. 



33 TiOa No action 



34 



SnO a 



Not perceptibly acted upon 
by acids 



Infusible alone 



B. B. alone infusible; with 
soda on charcoal yields 
metallic tin and gives 
white coating ; requires 
long blowing 



METALLIC LUSTER; STREAK COLORED. 



No. 


Composition. 


Action of Acids. 


Effects of Heating. 



35 



37 



39 



Carbon with 
some hydro- 
gen and 
oxygen 



CuO 



Carbon 



Magnesium, 
calcium, 
iron and 
aluminum 
silicate 



No action 



No action 



Acted upon by HNO 3 ; ad- 
dition of ammonia to dil- 
uted solution gives blue 
color 



Thoroughly mixed with 
niter deflagrates in closed 
tube 



In forceps burns with yel- 
low flame. Thoroughly 
mixed with niter, defla- 
grates in closed tube 



Gives copper with soda on 
charcoal. Moistened with 
HC1, colors B. B. pipe 
flame azure blue 



Burns without flame; gives 
no odor. Thoroughly 
mixed with niter, defla- 
grates in closed tube 

Anhydrous , fusible with 
intumescence in forceps 
or on charcoal 



io8 



B._ MINERALS WITHOUT METALLIC 

EXTERNAL CHARACTERISTICS. 



No.l 


Species. 


Luster and 
Color. 


Streak. 


Hardness and 
Tenacity. 


_ Remarks. 



I. STREAK GRAY, BLACK, OR GREEN. 



40 



42 



Pyroxene 
(Augite) 


L. Vitreous 
C. Gravish 
black, 
greenish 
black 


Dark gray, 
greenish 
gray 


H.=6 
Tough 
Brittle 


Franklinite 


L. Semi- 
metallic to 


Black 


H.=6.25 
Brittle 




dull vitre- 








ous 








C. Black 






Magnetite 


L. Semi- 
metallic, 


Black 


H.=6.25 
Brittle 




vitreous 








C. Black 







Monoclinic; crystals short 
and stout, cleavage 
nearly rectangular; gran- 
ular varieties are called 
coccolite; massive speci- 
mens are often composed 
of stout crystals with 
ends projecting on the 
surface. G.=3.4 

Isometric; occurs in octa- 
hedrons; usually slightly 
magnetic due to Fe 3 O 4 . 
Often occurs with red 
zincite 

Isometric; in small octahe- 
drons; usually in granular 
masses; magnetic, heavy. 
G.> 5 



II. STREAK BROWX. 



43 


Lignite 


L. Dull, 
generally ; 
if shining, 
resinous 
C. Brown, 


Brown, 
verging 
on black 


H.=2. 5 
Friable 


Sometimes laminated; gen- ' 
erally showing woody 
structure; often earthy; 
peat contains rootlets; 
air-dried contains con- 






black 






siderable water. G. = i.2 


44 


Cuprite 

(impure) 


L. Common 
C. Brown 


Brown 


H.= 4 

Brittle 


Impure with clay; often 
stained green on surface. 
G.>4 


45 


Sphalerite 


L. Resinous 
Adaman- 


Yellow to 
brown 


H.= 4 
Brittle 


Isometric; cleavage dis- 
tinct. G.=4 






tine 












Vitreous 












C. Black, 












brown 









LUSTER; STREAK COLORED. 



IOQ 



No. 


Composition. 


Action 


of Acids. 


Effects of 


Heating. 



40 



42 



Magnesium, 
calcium, 
iron, and 
aluminium 
silicate 



Oxide of Zn, 
Fe, and Mn 



Fe 8 4 



Same as for 31 



Acted upon by HC1; after 
dilution addition of 
K 4 FeCy 6 gives blue pre- 
cipitate 



Anhydrous; fusible with 
intumescence in forceps 
or on charcoal 



Becomes magnetic; when 
fused with soda and some 
niter on platinum foil the 
manganese present usu- 
ally colors the mass green 

Borax bead is bottle-green 
in R. F., in O. F. it is yel- 
low while hot, colorless 
when cold 



43 . 



44 



45 



Carbon, 
hydrogen, 
oxygen 



Cu,0 



ZnS 



Acted upon by HNO 8 ; after 
dilution, addition of am- 
monia colors solution 
blue 

Effervesces in hot HC1 with 
evolution of H 2 S 



Burns with yellow flame in 
forceps; gives off empy- 
reumatic odors. Mixed 
with niter deflagrates in 
closed tube 



Fuses easily in forceps and 
colors flame green. Yields 
bead of copper on char- 
coal 

Pulverized and heated on 
charcoal gives sulphur- 
ous odor ; slight zinc 
fumes; coating near assay 
which is yellow while hot, 
white on cooling. In open 
tube, very little (if any) 
sublimate of sulphur; 
slight odor of SO 2 and an 
acid reaction 



110 



B. MINERALS WITHOUT 

EXTERNAL CHARACTERISTICS. 



No. 


Species. 


Luster and 
Color. 


Streak. 


Hardness and 
Tenacity. 


Remarks. 



II. STREAK BROWN. 



46 



47 



Limonite 


L. Vitreous, 


Yellowish 


H. = 5-5 




resinous, 


brown 


Brittle 




silky, 








pearly 








C. Brown 






Amphibole 


L. Common 


Yellowish 


H. = 5 .5 


(Basaltic 


C. Black 


brown, 


Brittle 


hornblende) 




issr 








brown 




Cassiterite 


L. Adaman- 


Gray to 


H.=6.5 




tine 


light 


Brittle 




C. Brown 


brown 






to black 






Rutile 


L. Adaman- 


Light 


H.=6to6.5 




tine 


brown 


Brittle 




C. Reddish 








brown to 








red, black 







49 



III. STREAK RED. 



Usually earthy or botry- 
oidal, with a fibrous tex- 
ture. G. >4 



Monoclinic ; cleavage of 
crystals oblique 124; 
massive specimens often 
are made up of bladed 
crystals intersecting in all 
directions. G. = 3.3 

When of composition given 
sometimes called basaltic 



Principal tin ore. G.=6.8 



Very like tin ore, dis- 
tinguished as stated in 33 



Hematite 

(Red chalk) 


L. Common 
C. Dark red 


Brownish 
red 


H.=2 

Friable 


Massive, pulverulent, or 
compact; earthy; rather 
light 


Cinnabar 


L. Adaman- 
tine 
C. Cochi- 
neal red 


Scarlet 


H.=2 102.5 
Friable 


Massive granular, glisten- 
ing in specks; earthy 
when impure; volatile. 
G. from 3 to 8, > 8 when 










pure 



METALLIC LUSTER; STREAK COLORED. 



i u 



No. 


Composition. 


Action of Acids. 


Effects of 


Heating. 





46 2Fe a O 3 ,3H a O 



47 



49 



Magnesium, 
calcium, 
iron, and 
aluminum 
silicate 



SnO a 



TiO 5 



Acted upon by HC1; after 
dilution addition of 
K 4 FeCy 6 gives blue pre- 
cipitate 



Not perceptibly acted upon 
by acids 



Not acted upon 



Gives off much water easily 
in closed tube. Borax 
bead is bottle green in R. 
F. ; in O. F. yellow while 
hot, colorless cold. On 
charcoal becomes black 
and magnetic 

Anhydrous. In forceps or 
on charcoal fuses with in- 
tumescence 



B. B. alone infusible; with- 
soda on charcoal yields 
metallic tin and gives 
white coating; requires, 
long blowing 

Infusible alone 



Fe a 3 



HgS 



Slightly acted upon by 
HC1; addition of K 4 FeCy 6 
to dilute solution gives 
blue precipitate 



Not acted upon by either 
nitric or hydrochloric 
acid: attacked by aqua 
regia with separation of 
sulphur 



On charcoal becomes mag- 
netic if not too impure. 
Often gives off water in 
closed tube, due to clay 
present 

Heated in closed tube with 
sodium carbonate gives 
sublimate of i^ercury in 
small globules; alone 
gives a black sublimate, 
wholly volatile when pure. 
In open tube gives sul- 
phurous odor 



112 



B. MINERALS WITHOUT 

EXTERNAL CHARACTERISTICS. 



No. 


Species. 


Luster and 
Color. 


Streak. 


Hardness and 
Tenacity. 


Remarks. 



III. STREAK RED. 



Proustite 



53 



'54 



S5 



Pyrargyrite 



Cuprite 



Hematite 



L. Adaman- 
tine to dull 
C. Scarlet 
vermilion 


Scarlet ver- 
milion 


H.=2 tO 2. 5 

Brittle 


Generally found with other 
ores of silver. See 2, G. 
= 5-6 


L. Adaman- 
tine todul] 
C. Black to 
deep red 


Purplish 
red 


H.=a. S 
Brittle 


Occurs with other ores of 
silver, G.=5.8 


L. Adaman- 
tine, semi- 
metallic, 
common 
C. Carmine 
red, red- 
dish lead 


Brownish 
red 


H.= 4 

Brittle 


Cleavage distinct; often 
impure from clay; .copper 
ores are often stained 
green on the surface. G. 
= .5.8 to 6.1 


gray 








L.Common, 
semi-me- 
tallic 
C. Dark 
red. Part- 
ly steel 
gray 


Brownish 
red 


H. =5 (vari- 
able) 
Brittle 


Massive, granular, fibrous, 
lenticular, pulverulent, 
rarely botryoidal. G.>4 



IV.-YELLOW. 



56 


Limonite 


L. Common 


Yellow 


H. = i 


Usually earthy, containing 




(Yellow 


C. Yellow 




Friable 


much clay; very light 




ocher) 










57 


Sulphur 


L. Resin- 


Straw yel- 


H.=2 


G.-2 






ous, ada- 


low ' 


Brittle 








mantine 




Friable 








C. Sulphur 












yellow, 












grayish 












yellow 









METALLIC LUSTER; STREAK COLORED. 113 



No. 


Composition. 


Action of Acids. 


Effects of 


Heating. 



52 AgaAsSs 



53 



54 



55 



AgsSbSs 



Cu a O 



Fe,0 s 



Acted upon by HNO 3 , with 
separation of sulphur 



Acted upon by HNO 3 , with 
separation of sulphur. 
Copper plate in nitric so- 
lution coated with silver 



Acted upon by HNOs; ad- 
dition of ammonia to di 
lute solution gives blue 
color 



Acted upon by HC1; addi- 
tion of K 4 FeCy to dilute 
solution gives blue color 



On charcoal fuses easily 
and gives odors of sul- 
phurous and arsenic 
oxides. White sublimate 
in open tube. With soda 
and reducing flame bead 
of silver 

On charcoal fuses easily, 
with spurting, giving 
white coating of antimony 
oxide. With soda in re- 
ducing flame gives silver; 
red sublimate in closed 
tube, white in open 

B. B. colors flame green 
and fuses readily, yield- 
ing metallic copper on 
charcoal 



Anhydrous; becomes mag- 
netic on charcoal 



57 



Acted upon by HNOs; ad- 
dition of K4FeCy 6 to di- 
lute solution gives blue 
precipitate 



Becomes magnetic, if not 
too impure. Gives much 
water easily 

Burns with blue flame and 
sulphurous odor 



114 



B. MINERALS WITHOUT 

EXTERNAL CHARACTERISTICS. 



No. 


Species. 


Luster and 
Color. 


Streak. 


Hardness and 
Tenacity. 


Remarks. 



IV.-YEL.L.OW. 



58 


Cinnabar 
(impure) 


L. Common 
C. Yellow- 
ish red, 
cochineal 


Yellow 


H.=2.25 

Friable 


Massive granular, glisten- 
ing in specks; earthy,, 
containing clay 






red 








59 


Sphalerite 


L. Resin- 
ous, ada- 
mantine 
C. Gray, 
brown 


Light yel- 
low to 
brown 


H.= 4 
Brittle 


Isometric ; cleavage of 
crystals eminent; massive 
Missouri blende is glis- 
tening on a fresh surface; 
often contains iron. 












G.= 4 


60 


Siderite 


L. Vitreous 
to pearly 
C. Yellow, 
yellowish 


Pale yellow, 
brown 
when 
weathered 


H.= 4 
Brittle 


Rhombohedral; crystals 
often curved; often brown 
or black by weathering. 
G.= 4 






gray to 
yellowish 












brown 








61 


Zincite 


L. Adaman- 
tine 
C. Red, 


Orange 
yellow, 
brownish 


H.=4 
Brittle 


Cleavage distinct, often in 
laminated aggregations; 
occurs with Franklinite. 






orange, 
brown 


yellow 




G.> 4 


62 


Limonite 


L.Common, 
silky 
C. Brown 


Brownish 
yellow, 
ocher 
yellow 


H. = 5.5 
Brittle 


Usually earthy or botry- 
oidal, with a fibrous tex- 
ture; bog ore is sometimes 
loose, porous and earthy. 
G.>4 


63 


Amphibole 
(Basaltic 
horn- 
blende) 


L. Common 
C. Brown- 
ish black 


Grayish 
yellow, 
ocher 
yellow 


H. = 5 .5 
Brittle 


Monoclinic; cleavage 
oblique, 124; crystals 
usually long and slender, 
often acicular or bladed; 












massive specimens are 
nearly black and some- 
times made up of bladed 
crystals intersecting in 
all directions. When of 












composition given some- 
times called basaltic horn- 












blende 



METALLIC LUSTER; STREAK COLORED. 115 



No. 


Composition. 


Action 


of Acids. 


Effects of 


Heating. 



59 



60 



61 



62 



HgS 



ZnS 



FeCO 3 



ZnO 



2Fe a O 3 ,3H 2 O 



Magnesium, 
calcium, 
iron, and 
aluminum 
silicate 



Not acted upon by either 
nitric or hydrochloric 
acid. Attacked by aqua 
regia with separation of 
sulphur 



Acted upon by HC1, pro- 
d u c i n g effervescence, 
evolving H 2 S 



When powdered, hot HC1 
acts upon it, producing 
effervescence; addition of 
K 4 FeCye to dilute solution 
gives blue precipitate 



Acted upon by acids 



Acted upon by acids; addi- 
tion of K 4 FeCy e to dilute 
solution gives blue pre- 
cipitate 



Mixed with soda and heat- 
ed in closed tube gives 
small globules of mercury 
on side of tube; alone 
gives a black sublimate. 
In open tube gives sul- 
phurous odor 

On charcoal sulphurous 
odor, zinc fumes; coating 
(near assay) which is yel- 
low while hot, becoming 
white on cooling 



Blackens and becomes 
magnetic in reducing 
flame 



On charcoal, zinc fumes; 
coating (near assay) which 
is yellow while hot, be- 
coming white on cooling 



Becomes magnetic in re- 
ducing flame; gives much 
water in closed tube 



Anhydrous; on charcoal or 
in forceps fuses with in- 
tumescence 



B. MINERALS WITHOUT METALLIC 

EXTERNAL CHARACTERISTICS. 



No. 


Species. 


Luster and 
Color. 


Streak. 


Hardness and 
Tenacity. 


Remarks. 



V. STREAK GREEN. 



64 


Chlorite 


L. Common, 


Grayish 


H. = 2.s 


Schistose in structure; often 






pearly 


green 


Friable 


earthy by weathering; its 






C. Dark 






fracture is micaceous, 






green 






compact, or earthy; cleav- 












age eminent, folia flexible 












but not elastic 


65 


Serpentine 


L. Resinous 


Grayish 


H.=3 


Amorphous; massive; when 




(impure) 


(weak) 


green 


(variable) 


impure it is earthy, when 






C. Green, 




Friable 


pure its fracture is splin- 


F 




yellow, 




Brittle 


tery; unctuous feel; when 






and some- 






breathed upon smells bit- 






times 






ter; often mixed with cal- 






white; 






cite 






rarely 












dark 


^>-~ 






66 


^Chrysocolla 


L. Vitreous 


Bluish 


H.=2.4 to 3 


Amorphous; often reni- 






to earthy, 


green to 


Friable 


form; compact in texture 






resinous 


white 


Brittle 


and fracture; accompanies 






C. Green 


when pure 




other ores of copper, es- 












pecially malachite; seldom 












pure 


67 


Malachite 


L. Vitreous, 


Emerald 


H.= 3 .5 


Often reniform ; compact, 






pearly, 


green, 


Brittle 


fibrous, or earthy. G.=4 






silky 


paler than 










C. Emerald 


color 










green 








68 


Crocidolite 


L. Silky to 


Same as 


H.= 4 


Opaque 






dull 


color 


Fibers 








C. Laven- 




slightly 








der blue 




elastic 








or leek 












green 








69 


Pyroxene 


L. Common 


Grayish 


H.=5.S 


Monoclinic; crystals short 




(Common 


C. Blackish 


green 


Brittle 


and stout, cleavage dis- 




augite) 


green 






tinct, nearly rectangular; 












usually massive granular 












or composed of stout crys- 












tals with ends projecting 












on surface 



LUSTER; STREAK COLORED. 



117 



No. 


Composition. 


Action 


of Acids. 


Effects of 


Heating. 



64 



66 



68 



69 



Hydrous, 
magnesium 
iron, and 
aluminum 
silicate 



Hydrous, 
magnesium 
silicate 



Hydrous, 
copper 
silicate 



Hydrous, 
copper 
carbonate 



Iron and so- 
dium sili- 
cate; a form 
of asbestos 



Magnesium, 
calcium, 
iron, and 
aluminum 
silicate 



H a SO 4 and HC1 act upon it 
with a separation of silica 



Acted upon slightly by 
HNO 3 ; addition of am- 
monia to dilute solution 
gives blue color. In HC1 
decomposes with separa- 
tion of SiO 2 without gelat- 
inization 

Acted upon by HNO 3 
diluted, addition of am 
monia colors solution 
blue. Effervesces with 
acids 

Not acted upon by acids 



Gives off water readily; 
does not change color 



Gives off much water very 
readily; color changes to 
brown 



Gives off much water read- 



B. B. decrepitates and 
blackens ; colors flame 
green; gives off much 
water easily 



In closed tube gives a little 
water. B. B. fuses to a 
black magnetic glass, col- 
oring flame yellow 



Fusible with intumescence.- 



u8 



B. MINERALS WITHOUT METALLIC 

EXTERNAL CHARACTERISTICS. 



No. 


Species. 


Luster and 
Color. 


Streak. 


Hardness and 
Tenacity. 


.Remarks. 



V.-STREAK GREEN. 



70 



Amphibole 


L. Common 


Grayish 


(Common 


C. Blackish 


green 


horn- 


green 




blende) 







. = 5.5 

Brittle 



Monoclinic ; crystals long 
and slender, often acicu- 
lar; cleavage oblique, 124; 
granular or lamellar; usu- 
ally a mass of bladed crys- 
tals 



TI.-STREAK BLUE. 



ri 


Chrysocolla 


L. Vitreous, 


Greenish 


H.=2.4to 3 


Amorphous ; often reni- 






resinous 


blue, smalt 


Friable 


form; compact in texture 






C. Blue 


blue 


Brittle 


and fracture , accompa- 












nies other ores of copper, 












especially malachite 


'2 


Azurite 


L. Vitreous 


Smalt blue 


H.=3-75 


Often in incrustations; com- 






C. Lazuli 




Brittle 


pact, fibrous, or earthy. 






blue 






G.= 4 


73 


Lapis Lazuli 


L. Vitreous 


Smalt blue 


H.=5.5 


Often contains scales of 






C. Lazuli 




Brittle 


mica ; usually compact. 






blue 






G. = 2.5 



C. MINERALS WITHOUT METALLIC 

EXTERNAL CHARACTERISTICS. 



No. 


Species. 


Color. 


Luster. 


Hardness and 
Tenacity. 


Remarks. 



I.-VERY SOFT. 



74 


Calcite 


White 


Common 


H. 0.5 to i 


Usually a soft, white, por- 




(Rock milk) 






Pulverulent 


ous, earthy mass ; very 












light 



LUSTER; STREAK COLORED. 



119 



No. 


Composition. 


Action of 


Ac 


ids. 


Effects of 


Heating. 



70 



Magnesium, 
calcium, 
iron, and 
aluminum 
silicate 



Fusible with intumescence 



72 



73 



Hydrous, 
copper sili- 
cate 



Hydrous, 
copper car- 
bonate 



Sodium, alu- 
minum 
silicate, with 
sodium sul- 
phide and 
sulphate 



Acted upon by HNO 3 ; addi- 
tion of ammonia to dilute 
solution gives blue color. 
In HC1 decomposes with 
separation of SiO 2 , with- 
out gelatinization 

Acted upon by HNOsI solu- 
tion diluted, gives blue 
color on addition of am- 
monia. Effervesces with 
acids 

Slowly acted upon by HC1, 
giving odor of H a S 



Gives off much water easily 



B. B. decrepitates and 
blackens ; colors flame 
green. Gives off much 
water easily 



Fusible; loses its color 



LUSTER; STREAK WHITE OR LIGHT GRAY. 



No. 


Composition. 


Action of Acids. 


Effects of 


Heating. 



74 



CaCO, 



Acted upon with efferves- 
cence by HNO 3 and HC1; 
addition of H 2 SO 4 to di- 
luted solution gives white 
precipitate 



Infusible; assay after igni- 
tion reacts alkaline 



120 



C. MINERALS WITHOUT METALLIC 

EXTERNAL CHARACTERISTICS. 



No. 


Species. 


Color. 


Luster. 


Hardness and 
Tenacity. 


Remarks. 



I.-VEBY SOFT. 



75 


Kaolinite 


White 


Pearly 


H. = i 


Usually a soft, white, im- 










Friable 


palpable earthy mass, with 












unctuous feel and clayey 












taste and odor. Ordinary 












clay consists largely of 












kaolinite 


76 


Talc 


White, 


Eminently 


H. = i 


Usually in foliated or com- 






green 


pearly 


Friable 


pact masses, with an unc- 










Sectile 


tuous feel; folia flexible; 












cleavage eminent 


77 


Calcite 


White, gray 


Common 


H. = i 


Usually a compact, white 




(Chalk) 


to brown 




Friable 


mass, composed of shells. 












of foraminifers 


78 


Cerargyrite 


Gray to 


Resinous to 


H. = i to 1.5 


Very valuable ore of silver; 




(Horn sil- 


brown, 


dull 


Highly 


easy of treatment; com- 




ver) 


green, and 




sectile 


mon in South America, 






blue 




when pure 


Mexico, and southern 












United States. Plate of 












iron rubbed with it be- 












comes silvered. G. = 5-5 


79 


Niter 


White 


Vitreous 


H. = i.75 


Taste saline and cooling ; 










Friable 


occurs in incrustations or 










Brittle 


crystallized in right rhom- 












bic prisms 


80" 


Gypsum 


White, 


Vitreous, 


H.=2 


Occurs compact, fibrous, 






gray, yel- 


silky, 


Friable to 


and foliated, sometimes 






low, red, 


pearly 


brittle 


fine granular; cleavage 






and 






eminent; folia flexible. 






brown 






G. = 2.3 


81 


Sulphur 


Yellow, 


Adaman- 


H.=2 


Compact, in crusts or pul- 






g rav 


tine, resi- 


Brittle to 


verulent. G.=2 






brown 


nous 


friable 




82 


Mica 


Gray, 


Pearly 


H.=2. 5 


Usually in foliated or mica- 




(Muscovite) 


white, 




Friable 


ceous masses or thin 






pale yel- 






sheets; cleavage eminent; 






low or 






folia tough and elastic 






brown 









LUSTER; STREAK WHITE OR LIGHT GRAY. 



No. 


Composition. 


Action of Acids. 


Effects of 


Heating. 



75 



76 



77 



79 



80 



Si 



Hydrous, alu- 
minum sili- 
cate 



Hydrous, 
magnesium 
silicate 



CaCO, 



AgCl 



KN0 9 



CaSO 4 ,2H 2 O 



Hydrous, po- 
tassium, 
aluminum 
silicate 



No action 



No action 



Gives off much water read- 
ily 



Exfoliates before blowpipe. 
Yields very little water (if 
any) with difficulty 



Acted upon by HNO 3 and Infusible; assay after igni- 
HC1 with effervescence ;! tion reacts alkaline 
H 2 SO 4 added to dilute so-l 
lution gives white precipi- 
tate 

Not acted upon by HNOs or Fuses in flame of candle ; on 
HC1, but soluble in am- charcoal, metallic bead of 
monia silver 



Fuses in closed tube; bits 
of charcoal dropped in 
cause deflagration 

Fuses; leaves assay which 
is alkaline. Gives off wa- 
ter easily 



Dissolves in hot HC1 or 
HNO 3 ; after dilution ad- 
dition of barium chloride 
gives white precipitate 



Burns with a blue flame 
sulphurous odor 



Yields little water in closed 
tube 



122 



Q MINERALS WITHOUT METALLIC 

EXTERNAL CHARACTERISTICS. 



No. 


Species. 


Color. 


Luster. 


Hardness and 
Tenacity. 


Remarks. 



I.-VERY SOFT. 



83 


Mica 


Black 


Pearly 


H.=2.5 


Usually in foliated or mi- 




(Biotite) 






Brittle to 


caceous masses or thin 










friable 


sheets; cleavage eminent; 












folia tough and elastic 


84 


Chlorite 


Green; 


Pearly 


H.=a.5 


Schistose in structure; of ten 






rarelv 




Friable 


earthy by weathering; its 






bluish 






fracture is micaceous, 






red 






compact, or earthy; cleav- 












age eminent; folia flexi- 












ble but not elastic 


5 


Halite 


White, 


Vitreous to 


H. = 2.0 


Isometric, in cubes; mas- 






gray, red 


resinous 


Brittle to 


sive, compact, or granular; 










friable 


taste saline 


86 


Cryolite 


White to 


Vitreous to 


H.=2.5 


Massive; fracture uneven. 






brown 


greasy 


Brittle 


G.= 3 


87 


Anglesite 


White, 


Adaman- 


H.=2.7 to 3 


G.=6.i to 6.4 






gray to 


tine to 


Brittle 








yellowish 


vitreous 






88 


Carnallite 


Red 


Vitreous to 


H. = 2.7 


Soluble in water, bitter 








greasy 


Sectile 


taste, deliquescent 


II. SOFT. 


89 


Calcite 


All colors; 


Vitreous 


H.r= 3 


Crystals and cleavage 






white, 




Brittle 


rhombohedral ; usually 






gray, and 






compact, granular, or 






reddish 






fibrous ; sometimes tufa- 






common 






ceous ; impure varieties 












often contain clay and sil- 












ica. G. = 2.7 


90 


Anhydrite 


Gray, 


Vitreous, 


H.= 3 


Usually compact ; harder 






white, and 


resinous, 


Brittle 


and heavier than gypsum; 






bluish 


pearly 




fracture often splintery. 






gray 






G.= 3 .o 



123 
LUSTER; STREAK WHITE OR LIGHT GRAY. 



No. 


Composition. 


Action of Acids. 


Effects of 


Heating. 



Hydrous, 
potassium, 
magnesium 
iron, alu- 
minum 
silicate 

Hydrous, 
magnesium, 
iron, alu- 
minum 
silicate 



NaCl 



Fluoride of 
sodium and 
aluminum 

PbSO 4 



Mixture of 
potassium 
and mag- 
nesium 
chlorides 



Soluble in H 2 O; addition of 
solution of silver salt 
gives white, curdy precipi- 
tate of silver chloride. 



Yields little water in closed 
tube 



Gives off a moderate quan- 
tity of water rather read- 
ily; does not change color 



Fusible ; colors flame yel- 
low 



Fuses easily in flame of 
candle ; colors flame yel- 
low 

Fuses easily; metallic lead 
on charcoal 



Fuses easily 



CaCO s 



CaS0 4 



Acted upon by HC1 and 
HNOs, effervesces. Solu- 
tion diluted, addition of 
H a SO 4 gives white precip- 
itate 



Dissolves in hot HC1 and 
HNO 3 ; addition (after di- 
lution) of barium chloride 
gives white precipitate 



Infusible; assay after igni- 
tion reacts alkaline 



Fuses; assay after ignition 
reacts alkaline ; gives off 
little or no water 



124 



C. MINERALS WITHOUT METALLIC 

EXTERNAL CHARACTERISTICS. 



No. 


Species. 


Color. 


Luster. 


Hardness and 
Tenacity. 


Remarks. 


II.-SOFT. 


9i 


Cerussite 


White to 
gray 


Adaman- 
tine to 


H. = 3 to 3.5 
Brittle 


Occurs massive and stalac- 
titic. G.=6.5 








vitreous 






92 


Witherite 


White 


Vitreous 
to resi- 


3 to 3.5 
Brittle 


G.= 4 . 3 








nous 






93 


Chrysocolla 


Verdigris 
green, sky 
blue 


Shimmer- 
ing (vitre- 
ous, silky) 


H.= 3 -5 
Brittle 


Amorphous ; often reni- 
form; compact in texture 
and fracture; accompanies 
other ores of copper, es- 
pecially malachite 


94 


Aragonite 


White,gray, 
pale yel- 
low 


Vitreous, 
silky 


H.= 4 
Brittle 


Common in columnar ag- 
gregations ; harder than 
calcite. G.=2.9 


95 


Serpentine 


Yellow, 
green, and 
sometimes 
white; 
rarely 
dark 


Resinous 
(weak) 


H.= 4 

Brittle, 
friable 


Amorphous; massive; when 
pure its fracture is splin- 
tery, when impure it is 
earthy ; unctuous feel ; 
when breathed upon 
smells bitter; often mixed 






green 






with calcite 


96 


Sphalerite 


Yellowish 


Adaman- 
tine 


H.= 4 

Brittle 


Isometric, cleavage of crys- 
tals eminent ; massive 












Missouri blende is glisten- 
ing on a fresh surface. 
G.= 4 


97 


Fluorite 


White, 
grayish, 
light 
greenish 
and 
bluish, 


Vitreous 


H.= 4 

Brittle 


Isometric ; cleavage octa- 
hedral, distinct ; occurs 
crystallized, also massive, 
granular ; generally 1'ght 
colors. G.=3 






common 








98 


Dolomite 


White or 
grayish 


Vitreous, 
pearly 


H.=4 
Brittle 


Rhombohedral ; usually a 
crystalline mass ; often 
brown by weathering ; a 
little harder and heavier 












than calcite. G.=2.g 



125- 



LUSTER; STREAK WHITE OR LIGHT GRAY. 



No. 


Con 


Q position. 


Action of Acids. 


Effects of 


Heating. 



91 



92 



'93 



'94 



95 



96 



98 



PbCO 5 



BaCO, 



Hydrous, 
copper 
silicate 



CaCO< 



Hydrous, 
magnesium 
silicate 



ZnS 



CaF, 



CaMg(C0 3 ), 



Readily acted upon 
HNO 3 , effervesces 



by Yields lead with soda on 
charcoal, alone if heated 
carefully 



Acted upon by HC1 with 
effervescence and dilute 
acid solution gives white 
precipitate with H 2 SO 4 

Acted upon by HNO 3 ; ad- 
dition of ammonia colors 
solution blue. Decom- 
posed by HC1 with separa- 
tion of white silica, with- 
out gelatinization 

Acted upon by HC1 with 
effervescence ; after dilu- 
tion, addition of sulphuric 
acid gives white precipi- 
tate 



Effervesces with HC1 
strong odor of H a S 



Dissolves quietly in HC1 
solution diluted, netraliz- 
ed with ammonia and ox- 
alic acid added, gives a 
white precipitate 



When powdered, acted upon 
by HC1 with efferves- 
cence; after dilution, addi- 
tion of H 2 SO 4 gives white 
precipitate 



Fuses easily, color flame to 
yellowish green. 



Gives off much water easily 



Infusible; assay after igni- 
tion reacts alkaline 
Anhydrous 



Gives off much water very 
readily; changes color to 
brown 



Pulverized, heated on char- 
coal, sulphurous odor; 
slight zinc fumes; coating 
(near assay) yellow while 
hot, white on cooling 

Phosphoresces and decrep- 
itates; fuses; assay after 
ignition reacts alkaline 



Infusible ; assay after igni- 
tion reacts alkaline 



126 



C MINERALS WITHOUT METALLIC 

EXTERNAL CHARACTERISTICS. 



No. 


Species. 


Color. 


Luster. 


Hardness and 
Tenacity. 


Remarks. 



II.-SOFT. 



99 Siderite 



100 



101 



Smithsonite 



Calamine 



Yellow, 
yellowish 


Vitreous to 
pearly 


H.= 4 
Brittle 


gray, 
yellowish 
brown 






Gray, green, 
blue, 
brown to 


Vitreous, 
pearly to 
dull 


H. =4.5 to 5 
Brittle to 
friable 


white 






Gray, yel- 
low to 


Vitreous to 
dull 


H. =4.5 to 5 
Brittle 


brown 







Rhombohedral; crystals of- 
ten curved; often brown 
or black by weathering. 



Found in veins, but more 
generally in deposits of 
limestone; usually results 
from alteration of ZnS. 



Stalactitic, botryoidal, fib- 
rous, also massive and 
granular. G.=3.5 



III.-HARD. 



102 


Pyroxene 


Dark green, 


Semi-metal- 


H.= 4 .75 


Monoclinic; lamellar or 




(Diallage) 


brown or 


lic, pearly 


Brittle 


tabular; cleavage nearly 






gray 






rectangular. G.=34 


103 


Amphibole 


White gray, 


Vitreous, 


H.= 4 -75 


Monoclinic; crystals long, 




(Tremolite) 


greenish 


silky 


Brittle 


slender and bladed, often 






white 






fibrous (asbestos); fre- 












quently in crystals dis- 












seminated through a mass 












of dolomite; cleavage 












oblique, 124. G.=3 


104 


Amphibole 


Green 


Vitreous, 


H.= 4 -75 


Monoclinic; crystals long 




(Actinolite) 




silky 


Brittle 


and slender, sometimes 












fibrous (asbestos); usually 












in fibrous crystals dissemi- 












nated through a mass of 












talc or serpentine. G.=3 


105 


Analcite 


White to 


Vitreous 


H. =4.5105.5 


Isometric; trapezohedrons, 






pale red 




Brittle 


rarely massive. G. = 2.3 












to 2.4. Transparent to 












opaque 



127 



LUSTER; STREAK WHITE OR LIGHT GRAY. 



No. 


Composition. 


Action 


of Acids. 


Effects of Heating. 



100 



FeC0 3 



ZnCOs 



Hydrous, 
zinc silicate 



When powdered acted upon 
with effervescence by hot 
HC1; after dilution addi- 
tion of K 4 FeCy 6 gives blue 
precipitate 

Acted upon by HC1, effer- 
vesces 



Gelatinizes perfectly in HC1 



Blackens and becomes mag- 
netic in reducing flame 



Coating of zinc oxide with 
soda on charcoal 



Yields water in closed tube 



102 


Calcium, 




Fusible with intumescence 




magnesium, 








iron, silicate 






103 


Magnesium, 




Fusible with intumescence 




calcium, 








silicate 






104 


Calcium, 




Fusible with intumescence 




magnesium, 








and iron 








silicate 


v 


, 


105 


Hydrous, 




Water in closed tube; fuses 




silicate of 




easily to colorless glass 




sodium and 








aluminum 







-128 



Q MINERALS WITHOUT METALLIC 

EXTERNAL CHARACTERISTICS. 



No. 


Species. 


Color. 


Luster. 


Hardness and 
Tenacity. 


Remarks. 



III. HARD. 



106 


Apatite 


Usually 


Vitreous to 


H. = 5 


Hexagonal; crystals are 






green, 


somewhat 


Brittle 


hexagonal prisms with 






sometimes 


resinous 




pyramidal terminations, 






brown, 






having a more resinous 






etc. 






luster than beryl ; often 












massive. G.=3.2 


107 


Willemite 


White to 


Vitreous 


H.=5-5 


Usually massive ; also in 






gray, yel- 




Brittle 


hexagonal crystals. 






low, green, 






G.=3.g to 4.2 






brown 








108 


Enstatite 


Gray, yel- 


Vitreous to 


H.= 5 .5 


Orthorhombic; occurs mas- 






low, green 


pearly 


Brittle 


sive, fibrous, and lamel- 






to brown 






lar; translucent to opaque. 












G. = 3.i to 3.3 


109 


Bronzite 


Gray, yel- 


Vitreous to 


H. = 5.5 


Enstatite contains little or 






low, green 


pearly 


Brittle 


no iron, bronzite contains 






to brown 






over 5 per cent of iron 


no Monazite 


Red to dark 


Adaman- 


H. =5 to 5.5 


Monoclinic; generallyfound 






brown, 


tine or 


Brittle 


as rounded grains of sand, 






reddish 


resinous 




sometimes known as tho- 






or yellow- 






rium sand; translucent 






ish brown 








in 


Hypersthene 


Darkish 


Vitreous, 


H.=5to 6 


Orthorhombic ; massive, 






green to 


resinous, 


Brittle 


tubular and lamellar. 






brown and 


pearly, 




G.=3.4 to 3.5 






black 


almost 












metallic 






112 


Amphibole 


Black 


Vitreous 


H.=5-75 


Monoclinic ; crystals long 




(Horn- 






Tough 


and slender; cleavage ob- 




blende) 








lique, 124; granular; mas- 












sive specimens have com- 












mon luster and often con- 












sist of a mass of interlaced 












bladed crystals. G.=3-3 



I2 9 



LUSTER; STREAK WHITE OR LIGHT GRAY. 



NO. 


Composition. 


Action 


of 


Acids. 


Effects of Heating. 



106 Calcium 

phosphate 



Zinc silicate 



Magnesium, 
iron silicate 



Magnesium, 
iron silicate 



Phosphate of 
cerium, 
lanthanum, 
and didym- 
ium 

Iron and 
magnesium 
silicate, alu- 
minum 
sometimes 
present 

Magnesium, 
aluminum, 
calcium, 
iron silicate 



Soluble in hot HC1 or 
HNO 3 . Solution treated 
with H 2 SO 4 gives precipi- 
tate of calcium sulphate. 
The nitric acid solution 
added to excess of ammo 
nium molybdate produces 
immediately, or by gentle 
warming, a bright yellow 
precipitate, which shows 
the presence of phosphor- 
ic acid 



Soluble with difficulty in 
HC1 



Anhydrous. Fuses with 
difficulty ; coating of zinc 
oxide with soda on char- 
coal, yellow while hot, 
white on cooling 

Fusible with difficulty 



B. B. infusible 



B. B. on charcoal fusible 
with difficulty to a black 
magnetic mass 



Fusible with intumescence 



130 



C. MINERALS WITHOUT METALLIC 

EXTERNAL CHARACTERISTICS. 



No 


Species. 


Color. 


Luster. 


Hardness and 
Tenacity. 


Remarks. 



III. HARD. 



113 


Pyroxene 


White or 


Vitreous 


H. = 5 .75 


Monoclinic ; crystals short 




(Malacolite) 


gray 




Brittle 


and stout; cleavage near- 












ly rectangular ; granular 












varieties are called cocco- 












lite ; massive specimens 












often composed of crystals 












with ends projecting on 












surface. G. =3.4 


114 


Leucite 


White to 


Vitreous to 


H. =5.5106 


Isometric; trapezohedrons, 






gray 


resinous 


Brittle 


sometimes massive, trans- 












lucent to opaque 


H5 


Nephelite 


White to 


Vitreous to 


H. = 5.5106 


Hexagonal; transparent to. 






gray or 


greasy 


Brittle 


opaque 






yellow 








Ii6 


Pyroxene 


Grayish 


Vitreous 


H.=6 


Monoclinic; crystals short 




(Augite) 


black, 




Tough, 


and stout; cleavage nearly 






greenish 




brittle 


rectangular; granular va- 






black 






rieties are called coccolite; 












massive specimens are 












often composed of crystals 












with their ends projecting 












on the surface. G.=3.4 


*I7 


Orthoclase 


Reddish, 


Vitreous, 


H.=6 


Monoclinic ; two cleavage 






gray, 


pearly on 


Brittle 


planes at right angles ; 






white, yel- 


cleavage 




cleavage eminent, seen 






low, rarely 


surface 




when broken with a ham- 






green 






mer ; breaks into pieces 












resembling rhombohe- 












drons. G. =2.6 


118 


Albite 


White 


Vitreous, 


H.=6 


Triclinic; usually a mass of 








pearly on 


Brittle 


interlacing bladed crys- 








cleavage 




tals. G.:=2.62 








surface 






119 


Turquois 


Bluish 


Somewhat 


H.=6 


Massive, reniform, without 






green 


waxy 


Brittle 


cleavage. G.=2.y 


120 


Opal 


White, yel- 


Resinous 


H. = 5-5 to 


Amorphous ; generally in 






lowish, or 




6.5 


rounded masses with a 






brownish, 




Brittle 


compact, conchoidal frac- 






common 






ture; opalescent, present- 












ing internal reflections 



LUSTER; STREAK WHITE OR LIGHT GRAY. 



No. 


Composition. 


Action of Acids. 


Effects of Heating-. 



114 



116 



Magnesium, 
calcium sil- 
icate 



118 



119 



120 



Silicate of 
aluminum 
and potas- 
sium 

Silicate of 
aluminum 
and potas- 
sium 

Magnesium, 
calcium, 
iron, alu- 
minum sili- 
cate 



Potassium, 
aluminum 
silicate 



Sodium, alu- 
minum sili- 
cate 



Hydrous, 
aluminum 
silicate 

SiO 2 



Decomposed by HC1 with- 
out gelatinization 



Gelatinizes with acids 



No action 



No action with acids 



Soluble in HC1 



No action with acids 



Fusible with difficulty, in- 
tumescence 



B. B. infusible 



B. B. fuses quietly to a 
colorless glass 



Fusible with intumescence. 
Anhydrous 



Fuses with difficulty 



Fusible with difficulty, col- 
oring flame yellow 



Infusible; becomes brown. 
Gives off water 



Gives off water; fuses with 
effervescence when heated 
with soda on charcoal 



132 



C. MINERALS WITHOUT METALLIC 

EXTERNAL CHARACTERISTICS. 



No. 


Species. 


Color. 


Luster. 


Hardness and 
Tenacity. 


Remarks. 



III.-HAKD. 



Microline 



122 



Rutile 



White to 
light 
cream yel- 
low, also 
red, green 


Vitreous, 
sometimes 
pearly 


H.=6to6.5 
Brittle 


Red to 
brown 


Adaman- 
tine 


H.=6to6.5 
Brittle 



Same in composition as 
orthoclase, but triclinic; 
translucent to transparent 



Tetragonal, often prismatic 
and striated; translucent 
to opaque. G.=4.2 



IV. VERY HARD. 



123 


Olivine 


Green, yel- 


Vitreous 


H.-6.75 


Occurs usually in grains, 




(Chrysolite) 


low 




Brittle 


or granular disseminated 












through basalt in small 












glassy crystals; transpar- 












ent to translucent. 


124 


Quartz 


White, 


Vitreous 


H.=7 


Hexagonal, rhombohedral 




(Vitreous) 


gray, light 




Brittle 


division; crystals trans- 






pink, and 






parent, in hexagonal 






amethyst 






prisms with pyramidal 






blue are 






terminations; no cleavage 






common 






apparent; occurs also 












massive, either compact 













or granular 


125 


Quartz 


Brown, 


Somewhat 


H.= 7 


Cryptocrystalline; translu- 




(Chalce- 


yellow, 


waxy 


Tough 


cent; mamillary, nodular, 




donic) 


white, and 






or in layers lining cavities; 






red are 






compact, breaking with 






common 






conchoidal fracture 


126 


Quartz 


Red, brown, 


Common 


H.=7 


Cryptocrystalline; opaque; 




(Jaspery) 


green, and 


dull 


Tough 


usually in compact masses, 






yellow are 




, 


sometimes banded 






common 








127 


Garnet 


Yellow, 


Vitreous to 


H.=7 


In separate disseminated 






brown, 


resinous 


Brittle 


crystals (dodecahedrons 






red, and 






or trapezohedrons) or in 






black are 






granular masses; trans- 






common 






parent to opaque. G.>3 












and <5. Pyrope is in 












small granules 



133 
LUSTER; STREAK WHITE OR LIGHT GRAY. 



No. 


Con 


aposition. 


Action of 


Acids. 


Effects of 


Heating. 



121! Potassium, 
aluminum 
silicate 



122 



TiO s 



No action with acids 



Not acted upon 



Fuses with difficulty 



Infusible alone 



123 



124 



125 



126 



127 



Magnesium, 
iron silicate 



SiO 2 



SiO 5 



SiO 2 



Calcium, 
magnesium, 
iron, 

aluminum 
silicate 



No action with acids 



No action with acids 



No action with acids 



No action with acids 



Infusible (whitens). 



Fuses with effervescence 
with soda on platinum 
wire or on charcoal 



Fuses with effervescence 
with soda on platinum 
wire or on charcoal 



Fuses with effervescence 
with soda on platinum 
wire or on charcoal 



Dark varieties are fusible, 
usually leaving a mag- 
netic globule; others in- 
fusible 



134 



C MINERALS WITHOUT METALLIC 

EXTERNAL CHARACTERISTICS. 



No. 


Species. 


Color. 


Luster. 


Hardness and 
Tenacity. 


Remarks. 


IV. VERY HARD. 


128 


Tourmaline 


In all 


Resinous to 


H.=7 


Usually in separate crys- 






colors. 


vitreous 


Brittle 


tals disseminated through 






black most 






quartz, etc.; number of 






common 






sides of crystals some 












multiple of three; termin- 












ations low three-sided pyr- 












amids ; aggregations of 












crystals often coarse col- 












umnar; faces of crystals 












deeply striated. G.=3 to 












3-2 


129 


Andalusite 


White to 


Vitreous to 


H.=6 107.5 


Orthorhombic, often in 






gray, red, 


dull, 


Brittle 


square prisms transparent 






yellow, 


earthy 




to opaque. G. = 3.i to 3.2 






green, 












brown 


. 






130 


Beryl 


Green to 


Vitreous; 


H.=7-5 


Sometimes massive; usu- 






yellowish 


yellow 


Brittle 


ally in separate crystals 






and bluish 


varieties 




(hexagonal), terminated 






green, 


sometimes 




by plane bases; faces 






white to 


resinous 




often striated; usually 






light yel- 






shows cleavage parallel 






low, some- 






to base when broken. G. 






times blue 






= 2.7 






and red 








I3 1 


Spinel 


Black, red, 


Vitreous 


H.=7-7 to 8 


Isometric; usually in octa- 






gray, 




Brittle 


hedrons and rounded 






yellow, 






grains, transparent to 






green, 






opaque. G. =3. 5 to 4. 1 






blue 








132 


Topaz 


Pale yel- 


Vitreous to 


H.=8 


In right rhombic prsims 






low, white, 


adaman- 


Brittle 


usually differently modi-i 






blue, red, 


tine 




fied at the two extrem- 


i 




and green 






ities. G.=3-4 to 3.66 


133 


Chrysoberyl 


Various 


Vitreous 


H.=8.5 


Orthorhombic; transparent 






shades of 




Brittle 


to translucent. G.=3-5 to 






green to 






3-85 






yellow 




. 




134 


Corundum 


Blue, red, 


Adaman- 


H.= 9 






(Sapphire, 


white, 


tine to 


Brittle to 


Rough hexagonal crystals, 




ruby) 


gray, yel- 


vitreous 


tough 


massive to fine granular, 






low, green, 






transparent to opaque. 






and brown 






G. 3.9 to 4.1 



135 



LUSTER; STREAK WHITE OR LIGHT GRAY. 



No. 


Composition. 


Action of Acids. 


Effects of Heating. 


128 


Complex 
silicate 


No action 


Dark varieties are fusible 
with difficulty; and after 
fusion decomposed by 
H a SO45 others infusible 


I2 9 
130 


Silicate of 
aluminum 


No action 


Infusible 
Infusible 




Beryllium, 
aluminum 
silicate 


No action 


131 


Aluminate of 
magnesium 


No action 


Infusible 




132 


Aluminum 
silicate with 
silicon 
fluoride 


No action 


Infusible 




133 


Aluminate of 
beryllium 


No action 


With borax fuses 
great difficulty 


with 


^34 


Al,0 3 


No action 


Infusible 





136 



C. MINERALS WITHOUT METALLIC 

EXTERNAL CHARACTERISTICS. 



No. 


Species. 


Color. 


Luster. 


Hardness and 
Tenacity. 


Remarks. 



IV. VERY HARD. 



135 


Diamond 


White or 


Adaman- 


H. = io 


Isometric ; commonly in 






colorless, 


tine, 


Brittle 


octahedrons; usually 






sometimes 


greasy, 




transparent, translucent 






pale 


brilliant 




to opaque; conchoidal 






shades of 






fracture. G. =3.516 to 






yellow, 






3-525 






red, 












orange, 












green, 












blue, 












brown, and 












occasion- 












ally black 









. 137 
LUSTER; STREAK WHITE OR LIGHT GRAY. 



No. 


Composition. 


Action of 


Acids. 


Effects of 


Heating. 



135 Pure carbon No action 



At temperature of electric 
arc in air burns to CO 2 ; 
out of air changes to a 
sort of coke 



PART II. 
THE COMMON ROCKS. - 

The term rock is applied to the more extensive mineral 
masses which make up the earth's crust. Some of these 
constituent masses are composed of a single mineral, but 
most rocks are mineral aggregates. Pure limestone or pure 
siliceous sandstone are examples of rocks consisting of a 
single mineral; the first is composed of calcium carbonate 
and the second of silica. Nearly all rocks, however, are 
mineral aggregates, being composed of two or more min- 
erals ; even those composed essentially of a single mineral 
usually contain small quantities of other minerals. The term 
rock is ordinarily held to imply a solid, hard mass, but in 
geological usage it is not so restricted, but is equally ap- 
plicable to soft clay, loose sand, and hard granite. 

Although there have been distinguished and more or less 
fully described about nine hundred distinct mineral species, 
a small number of these make up the great mass of the 
earth's crust : only about twenty species are of prime im- 
portance as rock constituents ; these are the essential constit- 
uents of the rocks ; all other species are accessory or acci- 
dental minerals. 

CONSTITUENTS OF ROCKS. 

The principal rock-making minerals may be included 
under two general heads, siliceous and calcareous minerals. 
The first includes silica and the silicates ; the second the car- 
bonates, sulphates, and phosphates of calcium. 

The principal rock-making minerals are : 

SILICA, quartz, the most abundant mineral of the earth's 
crust. 

139 



140 



THE COMMON ROCKS. 



THE 
SILICATES. 



CALCA- 
REOUS 
MINERALS. 



rp, f Monoclinic, Orthoclase. 
Feld \ Triclinic ( Albite, Oligoclase, Ande- 
spart KSSS2, rthlte ' Labr " 



Feldspath- ( Nepheline. 
old < Leucite. 
group. ( Analcite. 
The Micas, Biotite, Muscovite, and Hydrous 

Mica. r . 

Amphibole group. 
Pyroxene group. 
Talc. 

Serpentine. 
Chlorite. 

f Calcite and Aragonite. 
I Dolomite. 
1 Gypsum. 
[Apatite. 



In addition to these most abundant rock-making species, 
the metallic ores, coal, peat, salt, and a few other minerals 
form limited, but, from an economical point of view, most 
important rock deposits. The metallic ores and coal have 
been already described as minerals. 



THE CLASSIFICATION -OF ROCKS. 

The classification of rocks can be based upon their phys- 
ical condition and texture, as crystalline and uncrystalline ; 
upon their mineral characters, as calcareous aud siliceous ; upon 
their mode of origin, as igneous and sedimentary; upon their 
structure and texture, as stratified and unstratified ; upon 
whether transformed from original condition, as metamorphic 
or not. 

A classification from any single point of view is unsatis- 
factory, because it fails to display important relationships 
among rocks and fails to give much desirable information. 
in regard to the characters and properties of rocks. 

For the purposes of the general student the most useful 
and instructive arrangement must involve to a certain 
degree all of the above distinctions. While, therefore, none 



SEDIMENTARY ROCKS. 141 

of these distinctions are ignored, the fundamental divisions 
here observed are geological and depend upon structure, 
mode of origin, and transformation. 

GENERAL CLASSES. 

The three most general classes under this arrangement 
are : 

I. Sedimentary or stratified rocks. 
II. Igneous or unstratified rocks. 
III. Metamorphic rocks. 

The sedimentary rocks appear far more extensively at 
the surface of the earth, and as a rule their constituents 
have simpler composition than those of the other classes; 
they will be first described. 



I. SEDIMENTARY ROCKS. 

The sedimentary rocks have resulted from the deposition 
of sediments or comminuted material, the material being 
primarily derived from the decomposition and disintegra- 
tion of pre-existing rocks. The rocks are therefore deriv- 
ative or secondary. The sedimentary rocks have been 
generally deposited from water, and one of their most 
obvious and common characteristics is stratification. So 
common is this origin and structure that the terms aqueous, 
stratified, and sedimentary are frequently used synony- 
mously. 

All the sedimentary rocks, however, have not been laid 
down under water; very limited masses have been accumu- 
lated on land : this fact gives rise to two divisions of the 
sedimentary rocks : 

A. Aqueous ; those laid down under water. 

B. Terrestrially deposited; those accumulated on land. 
It is true only in a very general sense that some of the 

aqueous rocks can be termed stratified, and the same is true 
to a greater extent as regards the terrestrial. It is evident, 
therefore, that the terms aqueous, sedimentary, and stratified 
are not strictly synonymous. 



142 THE COMMON ROCK'S. 

A. AQUEOUS ROCKS. 

The aqueous rocks may be further subdivided into : 

(a) Fragmental or mechanically deposited. 

(b) Chemically deposited. 

(c) Organic origin. 

(a) Fragmental Rocks. 

The fragmental rocks are uncrystalline and are usually 
either arenaceous or argillaceous, and are mechanically 
deposited. 

I. Arenaceous. 

The arenaceous, mechanically deposited rocks are com- 
posed of angular or worn fragments resulting from the dis- 
integration and wear of older rocks. The principal com- 
ponent of the arenaceous rocks is silica, though small 
quantities of the more common silicates are often present, as 
feldspar, mica, etc. To the arenaceous group the following 
varieties belong : 

SAND. Sand is comminuted rock material in an in- 
coherent state ; common sand is mainly quartz-grains, though 
some sands contain fragments of other minerals, as feldspar, 
mica, garnet, and iron oxide. Calcareous matter is also 
sometimes present. The roundness of the grains of sand 
depends upon the attrition to which they have been sub- 
jected ; river and land sands are accordingly less likely 
to be round than those of sea-beaches. 

GRAVEL. Gravel is composed of water-worn pebbles 
which range in size from a pea to a hen's egg. Various 
rock material may be present in the gravel, but, owing to 
its permanence, quartz is most common. A gravel beach 
usually has some sand mixed with the pebbles. The larger 
pebbles and cobblestones with or without gravel are usually 
called shingle. 

SANDSTONE. Sandstone is a consolidated rock made 
from sand. The cementing material may be calcium car- 



SEDIMENTARY ROCKS. 14$ 

bonate, clay, ferric oxide, or silica. The two cements last, 
named give the more durable stone. 

Varieties of sandstone are extensively used as a building- 
stone. It is quite durable and is easily quarried and cut. 
The " brownstone " used much in New York city and else- 
where for building is quarried in Connecticut and New 
Jersey. Sandstones when used for a building or wall should 
be placed with the bedding horizontal, since that is the 
position in which the stone will stand the greatest pressure 
and absorb the least moisture from the foundation. When 
pyrite is present in a building-stone it is likely to cause dis- 
integration. Sandstone is usually more or less laminated, 
especially if it contains clay. 

When sandstone splits readily into even plates or slabs,, 
it is called flagstone or paving-stone. Even-grained, friable- 
sandstones of various degrees of fineness are used as grind- 
stones or scythe-stones. 

NOVACULITE. This is an exceedingly fine-grained sand- 
stone, often called oilstone. It is found extensively in 
Arkansas and is valuable for whetstones. Sandstones often 
contain a considerable amount of clay, to indicate which 
they may, very properly, be termed argillaceous sandstones. 

QUARTZ CONGLOMERATE. A siliceous rock made up of 
sand, pebbles, or angular fragments of rocks cemented 
together. If the pebbles are rounded the conglomerate is a 
pudding-stone ; if angular, a breccia. The term " conglomerate " 
is often appled to the pudding-stone alone. 

GRIT. A grit is a hard, siliceous conglomerate, the 
grains being less rounded than in common sandstone. It is 
composed of vitreous quartz and was formerly sometimes 
used for millstones. 

2. Argillaceous. 

CLAY. Soft, very fine grained, almost impalpable, more 
or less plastic material, chiefly kaolinite in composition, and 
of various colors, as white, gray, yellow, red, brown, or 
black. When wet it can be kneaded between the fingers; 



144 THE COMMON ROCKS. 

when dry it is soft and friable and adheres to the tongue. 
It often contains much quartz-sand, and pulverized feldspar. 
Marl is a clay containing carbonate of lime, and the amount 
of carbonate may be so large as to place the rock among 
the chemically deposited. 

SHALE. Shale is a soft, fragile, argillaceous rock, having 
an uneven, slaty structure, splitting along planes parallel to 
the planes of deposit. Gray, brown, black, red, and other 
shades ; consists essentially of clay with some fine sand or 
pulverized feldspar. It is fine mud consolidated. Shales, 
by the addition of sand, graduate into fissile sandstones ; by 
the addition of calcareous matter into limestones ; by the 
addition of carbonaceous matter into coaly shales. 

FIRE-CLAY. A clay nearly free from alkalies and iron 
and capable of standing a great heat without fusing. It is 
usually of a light color and is found abundantly beneath the 
coal beds. 

(b) Chemically Deposited Rocks. 

OOLITE. Is a limestone composed of minute spherical 
grains resembling the roe of a fish, each grain being com- 
posed of concentrically deposited layers of calcite. PISO- 
LITE is a similar rock in which the grains are as large as 
peas. The unconsolidated oolitic grains are found as beach 
sand at Pyramid Lake, Nev.; similar but finer sand is now 
forming at Great Salt Lake. An oolitic rock is also found 
composed of calcareous, rolled sand cemented by calcium 
carbonate. This last is a fragmental rock. Extensive 
deposits of oolitic rock are known to exist. 

f GYPSUM. Is composed of calcium sulphate, and is a 
chemically deposited rock formed by the evaporation of the 
water holding it in solution. The decomposition is hastened 
by the presence of an abundance of common salt in the solu- 
tion. 

SALT. Common salt, like gypsum, is deposited by 
evaporation from waters holding it in solution. Salt and 
gypsum are generally associated, the latter being deposited 



SEDIMENTARY ROCKS. 145 

first. Salt occurs as an ingredient of other deposits, as salt 
shales ; also in thin sheets and enormously thick beds. 

TRAVERTINE. A massive limestone, formed by deposi- 
tion from calcareous springs or streams. It is usually cel- 
lular and more or less concretionary. A handsome com- 
pact, banded kind, translucent and of great beauty, comes 
from Mexico, and is sometimes called Mexican onyx. 

STALACTITE AND STALAGMITE. These are deposits, 
usually more or less columnar, formed on the roofs and floors 
of caves by deposition from solution. 

SILICEOUS SINTER. Is composed of opal silica. Occurs 
in compact, porous, and concretionary forms. It is deposited 
from hot siliceous waters, and is thus frequently found 
around geysers, forming mounds and occasionally terraces. 
From this fact it is sometimes called GEYSERITE. The .de- 
posit is mainly due to the evaporation of the water, but in 
some cases to the action of algae. 

CHERT, FLINT. A dark, compact rock occurring in 
nodules and in beds and composed almost entirely of chal- 
cedonic quartz. Its mode of origin is not thoroughly under- 
stood. Under the microscope the siliceous spicules of 
sponges and siliceous shells of diatoms, also calcareous shells 
or spines converted into silica, have been observed in it. 
The first two facts would indicate that the rock is, in part 
at least, formed from the segregated remains of organisms, 
while the last indicates a substitution of silica by a chemical 
process. The mass of the rock is believed to come more 
properly under Chemical Deposits, though in some cases it 
might be placed among those .organically formed. The 
nodules occur abundantly in chalk formations. 

BUHRSTONE. Is a highly siliceous, compact, though cel- 
lular rock. It is principally found in the Tertiary rocks of 
the Paris basin, and occurs in beds associated with sand and 
argillaceous marl deposits. The rock often abounds in land 
and fresh-water shells as well as in the stems and seeds of 
land and aquatic plants, all converted into silica. The exact 
mode of deposition is not known, but it was probably the 
action of siliceous waters on a previously existing fossilifer- 



146 THE COMMON ROCKS. 

ous rock, the silica replacing other material. The rock is 
chalcedonic quartz and is largely used for millstones in 
flouring-mills, cement-factories, potteries, chemical works, 
and other similar establishments. It has also been found in 
the Tertiary of South Carolina. 

MARL. Marl is a clay containing a greater or less pro- 
portion of CaCO 3 , from a small per cent to over one-half. 
Though testacea are usually abundant in marl beds, the 
CaCO 3 has more generally been deposited from waters 
holding it in solution ; to this extent marl is a chemically 
deposited rock. When the clay is taken into consideration 
marl might be classed, as already stated, as an argillaceous 
sedimentary rock. The marls are used as fertilizers. 



(c) Organic Origin. 

The rocks of organic origin are those mainly composed: 
of the remains of organisms. These remains have in many 
cases been acted upon, and to a certain extent the rocks 
formed by mechanical agencies, so that some of them might 
properly be classed as mechanically deposited rocks, but 
their essential origin rather than their accumulation is their 
more distinctive characteristic. 

LIMESTONE. This is a general term which includes all 
those rocks mainly composed of CaCO 8 , though they vary 
greatly in degree of purity. 

Most limestones are of organic origin and are marine 
deposits, though, as already seen, some are chemically de- 
posited by streams or springs. The organic limestones 
show every gradation of structure and texture. The de- 
posits range from thin laminae to beds several thousand feet 
in thickness. In some the organic remains are shown in 
almost perfect preservation, in others the organic origin is 
only evident under the microscope, and in still others the 
organic structure is no longer visible. From formations 
now being made in coral regions it is known that rocks of 
evident organic origin do not always show this origin in. 



SEDIMENTARY ROCKS. 147 

their texture ; oome of the more important and distinctive 
organic limestones are the following : 

SHELL-MARL. This is a friable rock mainly composed of 
shells and their fragments cemented together by calcium 
carbonate. Clay and sand are usually present. Such de- 
posits are generally formed in lakes and ponds. When com- 
pacted into solid stone they constitute fresh-water lime- 
stones. 

COQUINA. Shell-limestone. Coquina is a marine, porous 
shell-limestone made up almost entirely of fragments of 
shells, though occasional shells are entire. When first re- 
moved from the ground the rock is soft and may be easily 
cut; by exposure to the air it is greatly hardened. This 
rock is found in Florida and is extensively used in the forts 
and structures of St. Augustine. In the Florida rock the 
spaces between the shells are often partially filled with clear 
quartz sand. The stone is now being formed at numerous 
points along the Florida coast. Shell-limestones are formed 
at other places, but they differ from coquina in that they 
are more compacted ; such a rock is found along the Genesee 
river, near Rochester, N. Y. 

CHALK. Is a white earthy, friable limestone, composed 
mainly of the shells and shell-remains of rhizopods. 

HYDRAULIC LIMESTONE. This is an impure limestone 
containing clay and which, when calcined, yields a lime 
which furnishes hydraulic cement ; that is, a cement which 
sets under water. The indications of hydraulic properties 
in a limestone are compact texture, argillaceous odor, con 
choidal fracture, and sluggish effervescence. 

DOLOMITE. Is not distinguished by the eye alone from 
calcite limestone. It is calcium-magnesium limestone and 
occurs in beds often associated with gypsum and rock salt, 
also in irregular bands traversing limestone. The origin of 
dolomite is not fully understood. In some cases it seems to 
have been deposited as calcium carbonate and subsequently 
a portion of the calcium carbonate was replaced by magne- 
sium carbonate, by the chemical action of the magnesium 
salts in sea- water. 



148 THE COMMON ROCKS. 

In other instances this action seems highly improbable, 
and the rock was more likely formed as suggested by Hunt, 
being deposited in closed oceanic basins whose waters were 
rich in magnesium carbonate. Dolomite contains less than 
fifty per cent of magnesium carbonate, the remainder being 
calcium carbonate. Sing Sing marble, a typical dolomite, 
gives an hydraulic lime by cautious reduction, reducing 
the MgCO 3 with perhaps some of the CaCO,. Reduction at 
high temperature gives a fat lime. 

CALCAREOUS CONGLOMERATE. A rock composed of 
fragments of calcite or dolomite cemented by calcium car- 
bonate. If the pebbles are rounded the conglomerate is a 
pudding-stone ; if angular, a breccia. The term " conglomerate" 
is often applied to the pudding-stone alone. 

Other massive limestones are often named from the char- 
acter of the predominating organic remains such are coral 
rock, which consists of fragments of coral and other marine 
remains cemented by CaCO 3 ; crinoidal limestone is composed 
largely of the disks and stems of crinoids cemented together ; 
mummulitic limestone is a cream-colored rock consisting of 
nummulites, little flattened, disk-shaped fossils, cemented by 
calcite. Some of the pyramids of Egypt, including that of 
Cheops, are made of this rock. 

GREENSAND. An olive-green sand-rock, friable, con- 
sisting mainly of grains of glauconite (hydrous silicate of 
aluminum, iron, and potassium) with more or less sand. 
Many of the glauconite grains, under the microscope, are 
seen to be the casts of foraminiferous shells, and the proba- 
bilities seem to be that the glauconite was originally de- 
posited in organisms. 

SILICEOUS LIMESTONE. A limestone containing sili- 
ceous sand. It has a gritty feel under the fingers and may 
be distinguished by dissolving the pulverized rock in hy- 
drochloric acid, when the sand will be left as a gritty 
powder which is capable of scratching glass. 

MARBLE. Any limestone which occurs in large masses 
and is capable of receiving a polish is included under the 
-general term marble ; a more restricted use confines it to 



SEDIMENTARY ROCKS. 149 

the metamorphic, crystalline limestones. If the marble has 
colors distributed in blotches or streaks it is called varie- 
gated ; if it contains angular fragments it is called brecciated 
marble. Many of the calcareous rocks referred to give 
marbles. 

TRIPOLITE. An infusorial earth, consisting chiefly of 
siliceous shells of diatoms with the spicules of sponges, and 
is silica in the opal state. It resembles clay or impure 
chalk in appearance, but is a little harsh between the 
fingers and scratches glass when rubbed on it. It forms 
thick deposits, and is often found in old swamps beneath 
the peat. It derives its name from Tripoli in Africa, where 
it was first obtained. 

CARBONACEOUS DEPOSITS. Peat and the various forms 
of coal come under this head, all being of vegetable origin. 
Peat is a mass of partially disintegrated and decomposed 
vegetable matter. It has a black or brown color and is 
much richer in carbon than unchanged vegetable matter. 
In recent peat, or that in which the carbonization has not 
greatly progressed, the vegetable structure is readily de- 
tected by the unaided eye, but in the more perfect forms it 
can only be seen by the microscope. It occurs in many 
places and is valuable as a fuel. The various forms of coal 
have been already referred to as minerals. 

B. TERRESTRIAL OR LAND-FORMED ROCKS.* 

This division includes the rocks accumulated on land 
or areas not habitually covered by water. ,Such rocks are 
principally produced and accumulated by meteoric agen- 
cies. The most important of this class is the soil. 

SOIL. This is a general term for the products which 
result from the subaerial decomposition and disintegration 
of the more compacted rocks of the earth's surface. It is 

* There is no general agreement in the classification of the rocks here 
included under the term terrestrial. Nearly the same formations have 
been included under the terms aerial, subaerial, and ceolian, but none of.' 
these is thought to be as appropriately applicable as that adopted. 



15 THE COMMON ROCKS. 

an intimate mixture of such material and generally contains 
some animal and vegetable matter. The mineral matter of 
the soil often results from the rocks immediately below it, 
but it may be more or less transported. All fertile soils 
contain organic matter. 

ALLUVIUM. Is a term applied to the soil brought to 
gether by the ordinary operations of water, especially 
during times of flood. It generally constitutes the flats on 
either side of streams and is usually in layers varying in 
fineness, due to successive depositions. 

BLOWN SANDS. Loose sands, of whatever origin, may 
be blown into mounds or heaps, forming dunes or downs, 
and if they be calcareous sands or contain considerable cal- 
careous matter, they may by the action of rain-waters be 
converted into compact stone. 

LOESS. Is a term applied to certain widely distributed 
deposits which have the same general characteristics, but 
probably all have not been deposited in the same way. 
The material under consideration is a light-colored loamy 
earth, generally unstratified. It covers immense areas in 
northern China, in the pampas of South America, and 
occurs as extensive bluff-deposits along the Mississippi and 
its tributaries, along the Rhine, Danube, and other Euro- 
pean rivers. Somewhat similar deposits occur in the basin 
regions of our western country. The origin of these for- 
mations is not yet solved. In some regions they have been 
ascribed to the action of the wind, which is known to have 
deposited immense quantities of dust after carrying it 
through great distances. In certain arid regions dust- 
storms have been known to fill the atmosphere with dust 
for days, even obscuring the sun. Wind-blown dust is 
probably one of the sources of loess deposit ; another is 
thought to be rain-washed sediment from bare slopes. The 
loess of river-valleys generally was probably laid down in 
water during the periods of flooded lakes and rivers. 

GUANO. This substance is a mixture of organic matter^ 
ammonium salts and phosphate, of lime. It is a brown, light, 
porous body with an ammoniacal odor. The deposits of 



SEDIMENTARY ROCKS. !$! 

guano occur in rainless regions and are the droppings of the 
immense flocks of sea-fowl that have for centuries frequented 
the regions. South America and the rainless islands off the 
western coast of that continent contain the most noted de- 
posits. If the underlying rock is calcium carbonate it may 
be gradually converted into calcium phosphate. Similar 
deposits made by bats have been found in many caves. 

VOLCANIC TUFA is a rock formed from the comminuted 
fragmentary material ejected from volcanoes. These mate- 
rials are consolidated partly by pressure and partly by infil- 
trating waters. Vast quantities of fine matter are often 
ejected from volcanoes, the finest being termed ashes. There 
is a gradation from this through sand into the coarser vari- 
eties of ejected matter. The term " ash " is used because of 
its resemblance to the ash from wood or coal, but no result 
of combustion is implied. The tufas, or " tuffs " as the word 
is sometimes written, include the rocks formed from the 
consolidated ashes, sand, and finer material. 

The ejected material may fall into bodies of water, thus 
giving aqueous as well as terrestrial tufas. The finer ejected 
material, especially that of a sandy nature, is sometimes 
called peperino. The erupted matter from volcanoes and 
fissures forms other extensive land deposits, but thev cannot 
be included under the head of sedimentary rocks. 

TALUS. This is a term applied to the piles of earth and 
bowlders generally seen at the base of cliffs and mountain- 
slopes. Talus results from the unceasing action of gravity 
and meteoric agencies in dragging down the higher eleva- 
tions. In the case of cliffs, if the debris is not removed from 
the base, the precipice will in time be converted into a 
slope. 

DETRITUS. Detritus is the general term for earth, sand, 
alluvium,* silt, gravel, and mud. The material is derived to 

* The alluvial material is constantly carried into lakes, bays, etc., at 
the mouths of the rivers and streams. It is not under such circumstances a 
terrestrial deposit. In bays and harbors these shore deposits are usually 
called silt. They tend to delta formation and may eventually give rich 
alluvial lands. 






I $2 THE CO MAI ON ROCKS. 

a great extent from the wear of rocks through disintegrating 
agencies, attrition and decomposition. 

DRIFT. Drift is the unstratified sand, gravel; and stones, 
with more or less clay, deposited by glaciers ; it is also called 
TILL. 



II. IGNEOUS OR UNSTRATIFIED ROCKS. 

The first of these terms is applied to this class of rocks 
because heat has evidently been concerned in their origin, 
and the second because of the entire absence of true strati- 
fication. These rocks are believed to have consolidated from 
a fused or semi-fused condition. The term eruptive is some- 
times used as synonymous with the above terms, but eruptive 
is also used as the equivalent of volcanic, and will be so 
understood in this text. 

EVIDENCE OF ORIGIN. The igneous origin of these rocks 
is primarily involved in the accepted theory of the earth's 
origin, and they are believed to have been the rocks first 
formed and to have resulted from the cooling and solidifica- 
tion of the molten globe ; they are therefore the primitive 
rocks from which all others have been derived and must of 
necessity, at greater depths, underlie all superficial rocks. 
Subsequently and up to the present time all exposed igneous 
rocks have been produced from within the earth's crust, and 
there is the strongest ground for thinking that all have been 
in a molten or a pasty condition. The effects which the 
igneous rocks have frequently produced upon the sedimen- 
tary deposits with which they have come in contact, and the 
extreme similarity of these rocks, in many cases, to modern 
lavas, leave little doubt that heat has been an agent in their 
production. 

CHARACTERISTICS OF IGNEOUS ROCKS. The igneous 
rocks in general differ from the sedimentary by the absence of 
all lamination, due to the sorting of material ; by the texture, 
which is more or less crystalline, glassy, or compact ; by the 
absence of fossils, and by the marked difference in the, 
manner of occurrence. 



IGNEOUS OR UNSTRATIFIED ROCKS. 153; 

Besides the general terms of coarse and fine texture, 
descriptive of rocks, the igneous rocks display four distinct 
types of texture with gradations from one to the other. 
These types are designated as follows : 

ist. Glassy, in which the rock is a glass mixture, not 
showing distinct minerals ; is devoid of crystalline masses and 
has that texture which is best described by the term itself 
and thus universally recognized. The incipient stages of 
crystallization are often shown under the microscope in 
native glasses, by hair-like formations (trichites) and minute 
grains (spherulites). When the fused glass material is sub- 
jected to the action of escaping gases, there may be pro- 
duced a fine cellular or vesicular mass, thus giving rise to. 
pumiceous or scoriaceous texture. 

2d. Compact, in which the mass is made up of minute 
crystals too small to be seen by the eye alone. When the 
microscope reveals the crystals the rock is macrocrystalline, 
and when they cannot thus be seen, cryptocrystalline. Compact 
rocks are homogeneous and stony, not glassy in appearance. 

3d. Porphyritic, in which distinct crystals are inter- 
spersed throughout a ground mass which is glassy, minutely 
crystalline, or both. The large crystals are called pheno- 
crysts. This texture is thought to indicate two periods of 
crystallization, the phenocrysts forming first and the magma 
solidifying later. In some cases, if not all, the phenocrysts 
were formed before the rock was erupted and hence are 
said to be intratelluric. 

4th. Granitoid, in which the texture is wholly crystalline 
without any amorphous ground-mass. 

CLASSIFICATION OF IGNEOUS ROCKS. 

The igneous rocks for the purposes of the general 
student can be best and most significantly divided into two 
primary groups, plutonic and volcanic, with a less distinctly 
defined group forming an intermediate series. The typical 
members of the first two groups are distinctly different, 
but other members of the group approach each other 
by insensible gradations until they might with equal 



154 THE COMMON ROCKS. 

propriety be assigned to either ; these form the intermediate 
series and are sometimes classed as intrusive rocks. These 
divisions of the igneous rocks involve distinctions both in 
mode of occurrence and in the texture of the kinds. 

i. Plutonic Rocks. 

The plutonic rocks occur in the greater masses and have 
cooled and solidified at greater depths than the other groups 
and consequently more slowly. They have never been 
erupted on the surface. This slow cooling has led to a more 
perfect and wholly crystalline texture. They have the 
granitoid texture; that is, the rocks are made up of an 
aggregate of crystals more or less perfect without any un- 
crystallized ground-mass between the crystals. They are 
coarsely crystalline (macrocrystalline) and granular. The 
constitutent minerals are mainly quartz, the feldspars, mica, 
and hornblende. The principal rocks of this group are : 

GRANITE. Common granite consists of quartz, feldspar, 
and mica. Massive, with no appearance of layers in the 
arrangement of the mineral ingredients. G. = 2.5 to 2.8. 
The quartz usually transparent, bluish glassy, without 
cleavage ; the feldspar (usually orthoclase) opaque white or 
reddish with glistening cleavage surface ; the mica in glisten- 
ing scales, either whitish or black. When all the crystals 
are small and the rock evenly granular it is sometimes 
called eurite or granulite. When the feldspar is in well- 
defined crystals in a finer but still crystalline ground-mass, 
it is called porphyritic granite. When the rock also contains 
hornblende it is called syenitic granite. When the mica is 
replaced by hornblende it is called hornblende granite. 
Granite is generally plutonic, but sometimes metamorphic. 

PEGMATITE (Graphic Granite] consists mainly of quartz 
and feldspar with little or no mica or hornblende, the 
quartz existing as bent plates in the feldspar, giving in 
cross-section the appearance of Hebrew or Arabic charac- 
ters. 

SYENITE is a rock composed essentially of orthoclase 



IGNEOUS OR UNSTRATIFIED ROCKS. 155 

and hornblende. The hornblende may be replaced by 
biotite or augite, giving mica or augite syenite. 

The term syenite has been, in many places, used to 
describe the rock above referred to as hornblende granite. 
It still has a wide popular use in this sense in this country. 

DIORITE. A dark, speckled, greenish or grayish black 
rock, generally consisting of a crystalline aggregate of 
triclinic feldspar (oligoclase) and hornblende, though some 
varieties contain pyroxene or biotite. Quartz frequently 
present ; if in large quantity it makes quartz-diorite. Usu- 
ally granitoid in texture, though much finer than granite. 
Generally plutonic, sometimes metamorphic. 

DIABASE. A dark, greenish, crystalline rock, similar in 
appearance to diorite, but containing augite in place of 
hornblende. Usually fine-grained. Often contains olivine. 

GABBRO. A coarse-grained variety of diabase. 

The above selections include the more typical rocks of 
the plutonic group, but they graduate into each other and 
give rise to many varieties. 

Diorite and diabase are often intrusive, and accordingly 
fall also in the intermediate series of trappean rocks. 

2. Eruptive or Volcanic Rocks. 

The volcanic rocks have been brought to or near the 
surface by volcanic action and thus have been subjected to 
more rapid cooling than the plutonics. This has generally 
resulted in a wholly glassy or only a partially crystalline 
texture ; when partially crystalline, the crystals are im- 
bedded in an amorphous or glassy paste ; they are usually 
micro- or cryptocrystalline, and have a minutely speckled 
appearance. While generally the characters are as stated 
above, some of the volcanics are holocrystalline, but even 
then the principal mass of the rock is likely to be of very 
minute crystals. The difference in texture between the 
volcanic and plutonic rocks is due to their modes of oc- 
currence, which involves difference in the conditions of 
cooling. 

OBSIDIAN. Lava which has been completely fused and 



156 THE COMMON ROCKS. 

cooled rapidly. A volcanic glass. Gray to black. Breaks 
with a conchoidal fracture, the splinters often transparent. 
Most of the obsidians are essentially composed of ortho- 
clase. Its dark color and opacity are due to vast numbers 
of incipient crystals. 

Pitchstone has much the appearance of obsidian, but 
contains water. 

PUMICE. A finely vesicular, light-colored variety of 
scoria. It is so light that it will float upon water. A 
strikingly similar substance can be produced by injecting 
steam into certain iron slags. Pumice may result from 
different magmas, but the more common kind is composed 
essentially of orthoclase. It is often capillary or in thread- 
like masses, even silky. 

RHYOLITE. This is one of the most common kinds of 
lava erupted when the original igneous material is granitic 
in composition. The ground-mass is mainly orthoclase in 
minute crystals with more or less glass. It has the por- 
phyritic texture, the isolated crystals (phenocrysts) being 
of quartz and sanidin. Rhyolites are exceedingly abundant 
in the western United States. When coarsely granular it 
is sometimes called nevadite. Liparite and quartz trachyte 
are also names applied to forms of rhyolite. 

TRACHYTE. A light-colored, ash-gray rock. It consists 
of a ground-mass which is mainly minute orthoclase crys- 
tals, with little or no glass, with phenocrysts of sanidin of 
glassy luster. Often contains amphibole, pyroxene, or bio- 
tite, and is slightly porphyritic in texture. It graduates 
into rholite. 

PHONOLITE. A compact, grayish-blue or brown feld- 
spathic rock, somewhat slaty in structure. It clinks under 
the hammer. It differs in composition from trachyte in 
containing nepheline and sometimes leucite and horn- 
blende. It is a rare rock in this country. 

BASALT. This term is applied to many varieties of the 
volcanic rocks, which differ considerably in appearance. 
As most commonly applied it is a dark, almost black, 
cryptocrystalline rock, breaking with a dull, slightly con- 



IGNEOUS OR UNSTRATIFIED ROCKS. 1 57 

choidal fracture. It contains microscopic crystals of labra- 
dorite, augite, and usually olivine, in a ground-mass of the 
same. Magnetite is often an abundant constituent. 

DOLERITE, has the same composition as basalt, except 
the olivine, and is more coarsely crystalline. Its color is 
dark grayish. It is commonly called trap-rock, a term 
which is applied to several other granular volcanic rocks. 

ANDESITE. A dark-grayish rock, consisting essentially 
of triclinic feldspar (oligoclase or andesite), with horn- 
blende (or augite). 

3. Intermediate, Intrusive Rocks. 

In the plutonic and volcanic groups we have described 
only the more typical varieties, but there are many other 
igneous rocks which cannot with more distinctness be 
assigned to one rather than to the other of these groups. 
Many of these ill-defined rocks, in their mode of occurrence 
as well as their texture, are intermediate between the plu- 
tonic and the volcanic. The volcanic are generally the 
superficial igneous rocks ; the plutonic are the profound 
masses underlying the surface ; the intermediate series 
form the connecting conduits and sheets between them. 
Sometimes they are driven like wedges between the strata 
which rest upon the plutonics and are overlaid by the 
volcanics. The most common of the intermediate rocks are 
intrusive forms of dolerite, diorite, and diabase. They 
differ from the plutonic varieties only in their modes of 
occurrence, which may also affect their texture. The 
terms trap and greenstone are often applied to the basaltic 
intrusive rocks. 

FELSTTE is a light-colored intrusive rock, usually red- 
dish or gray. It is compact, fine-grained, and composed 
chiefly of feldspar and quartz without glass. It is often 
porphyritic in texture, the phenocrysts being of quartz or 
feldspar. The first is sometimes called quarts-porphyry, and 
the second porphyrite. The term porphyry is applicable to 
any rock which consists of a homogeneous base, with well- 
defined crystals of the same material or another mineral. 



1 5 8 



THE COMMON ROCKS. 



We thus often have greenstone porphyry as well as felsitic 
porphyry. The term porphyry is very generally employed 
by miners in our West for any rock that occurs in what 
they call veins. 



OTHER MODES OF CLASSIFICATION OF IGNEOUS ROCKS. 

No single common system for the classification of 
igneous rocks has been adopted. In addition to the divi- 
sions based upon their mode of occurrence, above given, 
other divisions, based upon chemical and mineralogical com- 
position, are very generally recognized, and are more fun- 
damental to the special student. This method of classifying 
gives the following groups for the rocks described: 

i(i) f Obsidian. ") The principal minerals 

j Pitchstone. present are orthoclase 
Granite-rhyo- J Pumice. and quartz, oligoclase 

lite family. , Rhyolite. { in subordinate quan- 
| Felsites. tity, with some horn- 

(_ Granites. J blende and mica. 

Principal minerals pres- 
ent are orthoclase and 
hornblende, some oli- 
goclase, pyroxene, and 
biotite. Quartz gener- 
ally absent; orthoclase 
predominating mineral' 

-syenite belongs to this 
nepheline and leucite 

replacing orthoclase. 

"] Plagioclase (soda-lime) 
feldspar is the predomi- 
nating mineral, with 
hornblende in consider- 
able quantity. Pyrox- 
ene and biotite may 
occur. Quartz in small 
quantity. 

Principal minerals pres- 
ent, plagioclase feld- 
spar (labradorite or 
} anorthite) and pyrox- 

Iene. Magnetite and 
olivine are often pres- 
ent. 





(2) 


' 




S y enite-tra- 
chytefamily. 

- 


Trachyte. 
Phonolite. 
Syenite. 

j 


I n t e r media t e 
group, contain- 
ing between - 
55 and 65 per 
cent of silica. 


(3) 


Nephelit< 
family, 
largely 

1 




Diorite-Ande- 
site family. 


Andesite. 
Diorite. 



(4) 



Basic group, con- 
taining be- 
tween 45 and 
55 per cent of 
silica. 


Basalt-Gab- ^ 
bro family. 


Basalt. 
Dolorite. 
Diabase. 
Gabbro. 



Ultra-Basic, con- 
taining gener- 
ally less than 
45 per cent of 

silica. 



(5) 



Rocks composed almost entirely of pyroxene or horn- 
blende and olivine. 

Serpentine rocks. 



METAMORPHIC ROCKS. 159 



III. METAMORPHIC ROCKS. 

The metamorphic rocks are those which have been 
produced by the transformation without disintegration of 
pre-existing rocks. This transformation generally involves 
one or more and often all the following changes greater 
hardness, different and more crystalline texture, develop- 
ment of different minerals.* 

One of the most important characteristics of many of the 
metamorphic rocks is a foliated structure. This term gener- 
ally refers to that structure brought about by the presence 
of minute scales, such as produce the fissile character of 
schists, but the term is now often used in a more general 
sense and is made to include cleavage. 

Until quite recently it was thought that metamorphic 
rocks were all originally sedimentary rocks, but it is now 
known that the original rocks often belonged to the igneous 
classes. Metamorphic rocks may be said to have had two 
dates, one of formation and one of transformation. 

The metamorphic rocks have great extent and thickness 
at many places throughout the world. The more important 
kinds are the gneisses, schists, clay slate, marbles, quartzite, 
and serpentine. The gneisses, schists, and slates have the 
foliated structure, the other kinds have not. The foliation 
in slates is usually termed cleavage. 

COMMON GNEISS. This rock has the general appearance 
and mineral composition of granite, but the ingredients are 
arranged in layers. Gneiss grades insensibly on the one 
hand into granite and on the other through the schists into 
sandy clays or clayey sands. It is now thought that gneiss 
has frequently resulted from the metamorphism of granite. 

If hornblende is also present as a constituent in the rock 
it becomes syenitic gneiss. 

*The term metamorphic has recently been used to include rocks altered 
by decomposition and disintegration. Such use greatly enlarges this class 
of rocks, but also makes the use of the term very general and less definite. 



l6o THE COMMON ROCKS. 

THE SCHISTS. More or less fissile rocks, made up largely 
of scales or thin crystals of the minerals from which they 
derive their names. The structure is called schistose, and 
differs entirely from that of slates. 

The structure is included under the general term of folia- 
tion. It is now thought that schists may have been derived 
either from igneous or sedimentary rocks. 

The varieties of schists are : 

Mica Schist. This is a grayish fissile rock consisting of 
mica, considerable quartz, and frequently some feldspar. It 
often contains garnets. Some varieties are used for flag- 
stones. 

Hydromica Schist. Composed chiefly of hydrous mica or 
of this with some quartz. The surface nearly smooth, pearly 
to faintly glistening in luster, grayish in color. 

Chlorite Schist. Grayish green, smooth but not greasy to 
the feel. Consists of chlorite with usually some quartz and 
feldspar. Often contains crystals of magnetite. 

Talcose Schist. Composed essentially of talc. Has the 
appearance and feel of talc. 

Hornblende Schist. Schistose, dark-colored, rough to 
the feel, composed of hornblende. 

CLAY SLATE (ARGILLITE). An argillaceous rock, split- 
ting into thin even slabs, the planes of cleavage running 
athwart the stratification planes. Many of the common 
slates contain considerable quantities of mica and hydro- 
mica in scales. They are generally derived from sediment- 
ary argillaceous rocks, but it is believed that they may 
result through the transformation of volcanic tufas. 

THE MARBLES. The marbles were originally common 
limestone, but metamorphism has produced in them a crys- 
talline-granular texture. They are either calcite, dolomite, 
or calcite-dolomite. They often contain mica, tremolite, 
talc, pyroxene or apatite. Some of the common marbles 
are: 

Statuary Marble. Pure white and fine grained. 

Architectural Marble is coarse or fine grained, white 
and mottled of various colors. 



METAMORPHIC ROCKS. l6l 

Verd Antique, Ophiolite. A marble containing serpentine. 

QUARTZITE is a changed siliceous sandstone, usually 
firm and hard. The grains and the cement holding them 
together are both silica. It generally requires the micro- 
scope to recognize the fragmental nature of the rock, but 
sandstones and quartzites graduate into each other. 

ITACOLUMITE is a schistose quartzite through which 
are distributed scales of mica, chlorite, and talc. The rock 
is often only slightly compacted and almost friable. It is 
sometimes the matrix in which diamonds are found in Brazil. 
It is slightly flexible, due to the schistose scales. 

SERPENTINE ROCK is composed of serpentine. Fine 
granular, easily scratched with a knife. Generally of a dark 
oil-green color and slightly greasy on a smooth surface. 
The massive compact varieties which receive a good polish 
are termed serpentine marbles. The origin of serpentine is 
not well understood ; in some cases it appears to be derived 
from magnesian clays, but perhaps more often by the altera- 
tion of chrysolitic, augitic, and hornblendic rock. 



INDEX TO TABLES. 



Table A Minerals with metallic luster 98-106 

41 B " without" " , streak colored 106-118 

C " " " " , " white or light gray 118-136 



Actinolite, 126 

Albite. 130 

Amphibole, (Actinolite) 126, (Basal- 
tic hornblende) no, 114, (Horn- 
blende), 106, 118, 128, (Tremolite) 
126 

Analcite, 126 

Andalusite, 134 

Anglesite, 122 

Anhydrite, 122 

Anthracite coal, 106 

Apatite, 128 

Aragonite, 124 

Argentite, 102, 104 

Arsenopyrite, (Mispickel) 100 

Augite, 108, 116, 130 

Azurite, 118 

Basaltic hornblende, no, 114 
Beryl, 134 
Biotite, 122 
Bituminous coal, 106 
Bornite, 98 
Bronzite, 128 

Calamine, 126 

Calcite, 118, 122; (Chalk) 120, (Rock 

milk) 118 
Carnallite, 122 



Cassiterite, 98, 106, no 

Cerargyrite (Horn-silver), 120 

Cerussite, 124 

Chalcedonic quartz, 132 

Chalcocite, 102, 104 

Chalcopyrite, 98 

Chalk, 120; red, 114 

Chlorite, 116, 122 

Chromite, 104 

Chrysoberyl, 134 

Chrysocolla, 116, 118, 124 

Chrysolite, 132 

Cinnabar, no, 114 

Coal Anthracite, 106; Bituminous, 

106 

Copper, 98 

Corundum (Sapphire, Ruby), 134 
Crocidolite, 116 
Cryolite, 122 
Cuprite, 98, 108, 112 

Diallage, 126 
Diamond, 136 
Dolomite, 124 

Enstatite, 128 
Erubescite, 98 



Fluorite, 124 
Franklinite, 104, 108 



163 



1 64 



INDEX TO TABLES. 



Galenite, IO2 

Garnet, 132 

Gold, 98 

Graphite, 100, 102, 106 

Gypsum, 120 

Halite, 122 

Hematite, (Specular iron ore) 102, 

104, 112, (Red chalk) no 
Hornblende, 106, no, 114, 118, 128 
Horn-silver, 120 
Hypersthene, 128 

Jasper, 132 
Kaolinite, 120 

Lapis Lazuli, 118 
Leucite, 130 
Lignite, 108 

Limonite, no, 114, (Yellow ocher) 
112, lib 

Magnetite, 104, 108 

Malachite, 116 

Malacolite, 130 

Melaconite, 104, 106 

Mica, (Muscovite) 120, (Biotite) 122 

Microcline, 132 

Mispickel, 100 

Molybdenite, 100 

Monazite, 128 

Muscovite, 120 

Nephelite, 130 
Niter, 120 

Ocher, yellow, 112 
Olivine (Chrysolite), 132 
Opal, 130 
Orthoclase, 130 



Proustite, 98, 112 

Pyrargyrite, 104, 112 

Pyrite, 100 

Pyrolusite, 104 

Pyroxene, (Augite) 108, 116, 130,, 

(Diallage) 126, (Malacolite) 130 
Pyrrhotite, 100 

Quartz (Vitreous, Chalcedonic, Jas- 
pery), 132 

Red chalk, no 

Ruby, 134 

Rutile, 98, 106, no, 132 

Sapphire, 134 
Serpentine, 116, 124 
Siderite, 114, 126 
Silver, 100 
Smithsonite, 126 
Specular iron ore, 102 
Sphalerite, 108, 114, 124 
Spinel, 134 
Stephanite, 104 
Stibnite, 100 
Sulphur, 112, 120 

Talc, 120 
Tennantite, 102 
Tenorite, 106 
Tetrahedrite, 102 
Topaz, 134 
Tourmaline, 134 
Tremolite, 126 
Turquois, 130 

Willemite, 128 
Witherite, 124 

Zincite, 114 



GENERAL INDEX. 



PACK 

Actinolite 82 

Adularia . 87 

Agate, common 75 

fortification 75 

, moss 76 

Alabaster 68 

Albite 87 

Alexandrite 65 

Alluvium 150 

Almandine, almandite 84 

Amethyst 75 

Amianthus 82 

Amphibole 81 

group . 80 

Amphigene 88 

Analcime, analcite 89 

Andalusite 90 

Andesite 88, 157 

Angles, constancy of 10 

, interfacial 2 

, plane, solid 2 

Anglesite 50 

Anhydrite 69 

Anorthite 88 

Antimony, glance 60 

, gray ...... 60 

Anthracite . 94 

Apatite . . . 69 

Aquamarine 84 

Argentite, silver glance 40 

Argillite 160 

Arragonite 72- 

165 



166 GENERAL INDEX. 

PACK 

Arsenopyrite 55 

Asbestu s 82 

Asbestus, ligniform 82 

Augite 80 

Aventurine . 75 

Axes, crystallographic 6 

of symmetry 3 

, principal 17 

Azurite 48 

Basalt 156 

Bauxite 63 

Beauxite 63 

Beryl 83 

Biotite 86 

Bituminous coal 95 

Black copper ore 46 

silver ore, stephanite 41 

Blende, zinc 51 

Bloodstone 76 

Blown sand 150 

Blowpipe test for iron, lead, zinc 30 

, use of 29 

Bog-iron ore 58 

Bornite 44 

Bort 32 

Breccia 143 

Brittleness, property of 26 

Bronzite 81 

Buhrstone 76, 145 

Cairngorm 75 

Calamine 52 

Calcite 70 

Calcium, compounds of 67 

phosphate 69. 

sulphate, hydrous 69 

Calcspar : 70 

Carbonaceous deposits 149 

Carbonates 32 

Carbuncle 85 

Carnallite 67 

Carnelian 76 

Cassiterife 61 

*"at's eye, chrysoberyl 65 

quartz 75 



GENERAL INDEX. l6/ 

PACK 

Cerargyrite, horn-silver 41 

Cerussite 50 

Chalcedony 75 

Chalcocite 45 

Chalcopyrite 45 

Chalk . 71, 147 

, French 92 

Chalybite 59 

Chemical properties of minerals 27 

Charcoal, use of 28 

Chert 145 

Chlorite. '. 94 

Chloropfcane 67 

Chromite Bo 

Chrysoberyl 64 

Chrysocolla 48 

Chrysolite 83, 

Chrysoprase 76 

Chrysotile 93 

Cinnabar 42: 

Cinnamon-stone 84 

Clay, common 90, 143, 

, fire 144 

Cleavage 8, 9 

Coal, anthracite 94 

, bituminous 96 

Coal, brown 95 

, cannel 95 

, mineral 94 

Colophonite 84 

Color of minerals 25 

Columnar structure 23 

Concretions ' 24 

Conglomerate, calcareous 148 

, quartz 143 

Copper, common, test for 44 

glance 45 

, native, occurrence of 43 

ores 44 

pyrites 45 

, variegated 46 

, vitreous 45 

Corundum 62 

Coquina 14? 

Crocidolite 82 

Cryolite 66 



168 GENERAL INDEX. 

PAGE 

Crystalline aggregates 23 

systems. i ! 

Crystallography, geometric .,.. 2 

, physical 2 

Crystals, definition I 

, relating to 8 

, distortion in 19 

, multiple 20 

, parallel grouping 20 

, twins, contact, penetration 21 

Cuprite 46 

Dendritic structure 23 

Detritus 151 

Diabase . 155 

Diallage 80 

Diamond 32 

, source of 33 

Diaspore 63 

Diorite 155 

Distortions in crystals 19 

Dog-tooth spar 72 

Dolerite 157 

Dolomite 73, 147 

Downs 150 

Drift 151 

Drusy surface 23 

Dunes 150 

Edge, beveled 9 

, replaced 9 

. , truncated 9 

Edges I 

Electro-silicon 78 

Emerald 83 

Emery 63 

Enstatite :, 81 

Erubescite. 46 

Essonite 84 

Eurite 154 

Faces 1,9 

, curved, striated 20 

Feldspar 86, 87 

, common, potash 87 

, soda > 87 



GENERAL INDEX. 169 

PAGE 

Telsite 157 

Felspathoid group 88 

Fibrous structure 23 

Fiorite 77 

Flagstone , 143 

Flexibility, property of 26 

Flint 76, 145 

Fluorite 67 

Fluorspar 67 

Fluxes , 30 

Foliated structure 158 

Forceps, use of 28 

Forests, petrified 76 

Forms, clinometric 6 

, closed, open 18 

, fundamental 8 

, holohedral, hemihedral 19 

, orthometric 6 

, unit 8 

Franklinite 58 

Gabbro 155 

Galena 50 

Galenite 50 

Garnet , 84 

, precious i- 84 

Geodes 24 

Geyserite 77, 145 

Glauconite 148 

Gneiss, common , 159 

, syenitic .._ .*. 159 

Gold, method of obtaining 37 

, native ... . 36 

, occurrence of 36 

, production in U. S 38 

Granite 154 

, graphic , 154 

, hornblendic 155 

, porphyritic 154 

, syenitic 154 

Granular structure 23 

Granulite 154 

Graphite 33 

Gravel 142 

Gravity, specific 26 

'Gray antimony. 66 



GENERAL INDEX. 

PACK 

Gray copper ore 46 

Greensand ' 148 

Greenstone, trap 157 

Grindstones 143 

Grit * 143 

Guano 150 

Gypsum 68, 144 

Halite....* 65, 

Hammer, and anvil, use of 28 

Hardness table of 26 

Heliotrope 76 

Hematite, brown 58 

, red 56 

Hemihedral 19, 

Holohedral \ 19 

Hornblende 83, 

Horn-silver, cerargyrite 41 

Hypersthene 81 

Ice-stone 66 

Iceland spar 72 

Indices, rationality of 9, 

Indicolite 92 

Infusorial earth 79 

Iron carbonate 59 

, native 53 

, ores of 54 

Pyrites 54 

Isomorphism 21 

Itacolumite 161 

Jasper 76 

Jet....- 95 

Kaolinite 90 

Labradorite 88 

Lamellar structure 23 

Lapis lazuli. 85 

Law of axial ratios ; gfr 

Lead carbonate 50 

, ores of 49 

sulphate 50 

sulphide 49 

Lepidolite 86, 



GENERAL INDEX. 



Leucite 88 

Lewis, H. C 33 

Limestone, chemically deposited 71 

, crinoidal 148 

, hydraulic 147 

, lithographic 71 

, nummulitic 148 

, oolitic 71 

, origin organic 146 

, siliceous 148 

Limonite 58 

Liparite 156 

Lithographic limestone 71 

Loess I5a 

Magnesium limestone 73 

Magnetic pyrites 55 

Magnetite 57 

Malachite 47 

Malacolite 80 

Malleability, property of 26 

Manganese, black oxide of 60 

Marble 148, 160 

, architectural 160 

, brecciated 149 

, serpentine 161 

, statuary 160 

, variegated 149 

Marl 146 

, shell- 147 

Martite 57 

Melaconite 47 

Mica 85 

, uses of 86 

Microline 88 

Milky quartz ; ... 75 

Mineralogy, chemical 2 

, crystallographic 2 

, definition i 

, descriptive , 3 

Mineral species I 

Minerals, definition I 

Mispickel 55 

Monazite 64 

Mortar, steel , 28 

, agate 4 28 



1/2 GENERAL INDEX. 

PAGE 

Moss-agate .....* , 76 

Mountain leather , , 82 

Multiple crystals , 20 

Mundic. 56 

Muscovite 86 

Nepheline, nephelite. 89 

Niter * 66 

Novaculite 143 

Obsidian 155 

Ocherous ore, iron .. 58 

Odors of minerals 26 

Oilstone -. 143 

Oligoclase 89 

OH vine * 83 

Onyx *. 76 

Oolite 144 

Oolitic limestone , 71 

Opal ,...,, , 77 

Opalescence... ...... ,.,..,., ....... 25 

Ophiolite ... ., 93, 161 

Orthoclase 87 

Parallel grouping 20 

Parameters, rationality of 9 

Paving-stones , , 143 

Peat , , 149 

Pegmatite , 154 

Peperino ... 151 

Peridot 83 

Phonolite ,. 156 

Phosphorescence , 25 

Physical properties of minerals,. 25 

Plagioclase .,.. t . . . . 88 

Planes, like , 9 

, location by axes 7 

, similar... , 9 

Platinum, native. , .,.,.. 38 

Play of colors , , 25 

Plumbago 33 

Porphyrite 157, 158 

Porphyry, quartz- 15^ 

Proustite, red silver ore ^ 41 

Pseudomorphs 21 

Pudding-stone. ., ... ..,..,. 143 



GENERAL INDEX. I 7$ 

PAGE 

Pumice 156 

Pyrargyrite, ruby silver . . 40 

Pyrites, iron.. . . 54 

Pyrolusite 61 

Py rope 84 

Pyroxene division . . 79 

group 80 

Pyrrhotite 55 

Quartz 74 

, chalcedonic series 75 

, crystalline series 74 

, granular 76 

Quartzite 161 

Reagents 30 

Red copper ore 46 

Rhyolite 156 

Rock crystal 74 

-forming minerals. 139, 140 

milk 72 

Rocks, aqueous 142 

, chemically deposited 144 

, classification of 140 

Rock salt * 65 

Rocks, common 139 

, constituents of ; 139 

, eruptive ^ . * , 155 

, general classes of 141 

, igneous, classification of . 153 

, characteristics of . . . . i. 152, 153 

, origin of. ; < 152 

, unstratified < ***. 152 

, intermediate ;....* *... 157 

r intrusive -. 157 

, land-formed . * 149 

, metamorphic 159 

organic in origin 146 

, plutonic < * 154 

, sedimentary 141 

, tabular classification of... 157 

, volcanic f 155 

Rose quartz ...*........ 75 

Rubellite . 92 

Rubies, Arizona. ................ 4 85 

Ruby, common ...;;*.....-.... * ...-.<.. * 66 



174 GENERAL INDEX, 

PAGE 

Ruby, oriental 63 

Ruby silver, pyrargyrite 40 

Rutile 62 

Salt, common rock 66, 144 

Saltpeter 66 

Sand 142 

Sands, blown 149 

Sandstone ' 142 

, flexible, itacolumite 161 

Sanidin 87 

Sapphire 63 

Sard 76 

Sardonyx 76 

Satin spar, calcite 72 

, gypsum * . 68 

Schists 160 

chlorite 160 

hornblende 160 

hydromica 160 

mica 1 60 

talcose 160 

Scythestone 143 

Sectility, property of 26 

Selenite 68 

Serpentine, precious, common 93 

rock 161 

Shale 144 

Siderite 59 

Silica 74, 139 

Silicates, classification of 78 

Siliceous sinter 77 

Silver glance, argentite 40 

Silver, native 39 

, ores of , 40 

, sources of 41 

Slate, clay 160 

Smithsonite 52 

Smoky quartz 75 

Soapstone 92 

Soil 149 

Spathic iron ore 59 

Specific gravity 26 

Specular iron ore 56 

Sphalerite 51 

Spinel 64 



GENERAL INDEX. 1/5 

PAGE 

Stalactites 71, I4 g 

Stalactitic structure 24 

Stalagmites y lt I45 

Steatite 9 2 

Stephanite, black silver ore 41 

Stibnite 60 

Stratified structure 24 

Streak of minerals.. . . . 25 

Sulphur, native ^4 

, sources of 35 

Syenite I55 

Symmetry, axes of 3 

, center of 4 

, crystallographic 3 

, elements of 3 

, planes of 3, 17 

Systems, crystalline, isometric n 

, monoclinic 15 

, orthorhombic ..... 14 

, tetragonal, hexagonal 12 

, triclinic 5 

Tables, description of use 96 

Talc 92 

, indurated 92 

Talus 151 

Tennantite < 46 

Tests, miscellaneous . < 31 

Tetrahedrite 45 

Till 152 

Tin ore, black 61 

oxide 61 

stone 61 

Topaz 89 

Tourmaline 91 

Trachyte 156 

, quartz 156 

Trap-rock 157 

Travertine 71, 145 

Tremolite 82 

Tridymite 77 

Tripolite 77 

Tubes, closed 29 

, test with 31 

, open 29 

, test with 30 



176 GENERAL INDEX. 

PAGE: 

Tufa, calcareous 71 

, volcanic ;.. 151 

Turquois 63 

Ultramarine 85 

Verd-antique v 93i 161 

White lead ore 5 

Willemite 52 

Wire, platinum, use of 29 

Witherite 74 

Zinc blende 53 

carbonate 53 

, ores of 5i 

silicate 52 

Zincite 52 

Zonal relations J o 

Zone 10 







X/ 



SHORT-TITLE CATALOGUE 

OF THE 

PUBLICATIONS 

OF 

JOHN WILEY & SONS, 

NEW YORK, 
LOKDOX: CHAPMAN & HALL, LIMITED. 



ARRANGED UNDER SUBJECTS. 



Descriptive circulars sent on application. 

Books marked with an asterisk are sold at, vet prices only. 

All books are bound in cloth unless otherwise stated. 



AGRICULTURE. - 

Armsby's Manual of Cattle- feeding 12mo, $1 75^ 

Downing's Fruits and Fruit- trees of America 8vo, 5 00 

Grotenfelt's Principles of Modern Dairy Practice. (Woll.) . . 12mo, 2 00 

Kemp's Landscape Gardening 12mo, 2 50 

Maynard's Landscape Gardening as Applied to Home Decora- 
tion 12mo, 1 50 

Stockbridge's Rocks and Soils 8vo, 2 50 

Woll's Handbook for Farmers and Dairymen 16mo, 1 50 

ARCHITECTURE. 

Baldwin's Steam Heating for Buildings 12mo, 2 50 

Berg's Buildings and Structures of American Railroads. . . ,4to, 5 00 

Birkm ire's Planning and Construction of American Theatres.Svo, 3 00 

Architectural Iron and Steel 8vo, 3 50 

Compound Riveted Girders as Applied in Build- 
ings 8vo, 2 00> 

Planning and Construction of High Office Build- 
ings 8vo, 3 50 

Skeleton Construction in Buildings 8vo, 3 00 

Briggs's Modern American School Buildings 8vo, 4 00 

Carpenter's Heating and Ventilating of Buildings 8vo, 3 00 

Freitag's Architectural Engineering 8vo, 3 50 

" Fireprooflng of Steel Buildings 8vo, 2 50 

Gerhard's Guide to Sanitary House-inspection 16mo, 1 00 

" Theatre Fires and Panics 12mo, 1 50 

Hatfield's American House Carpenter 8vo, 5 00 

Holly's Carpenters' and Joiners' Handbook 18mo, 75 

Kidder's Architect's and Builder's Pocket-book.. 16mo, morocco, 4 00 

Merrill's Stones for Building and Decoration 8vo, 5 00 

1 



Moiicktoirs Stair-building 4to, 4 00 

Patton's Practical Treatise on Foundations.....! 8vo, 5 00 

Siebert and Biggin's Modern Stone-cutting' and Masonry. .8vo, 1 50 

Wait's Engineering and Architectural Jurisprudence Svo, 600 

Sheep, 6 50 

Law of Operations Preliminary to Construction in En- 
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Sheep, 5 50 

Law of Contracts 8vo, 3 00 

Woodbury's Fire Protection of Mills Svo, 2 50 

Worcester and Atkinson's Small Hospitals, Establishment and 
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with Plans for a Small Hospital 12mo, 1 25 

The World's Columbian Exposition of 1893 Large 4to, 1 00 

ARMY AND NAVY. 

Bernadou's Smokeless Powder, Nitro-cellulose. and the Theory 

of the Cellulose Molecule TOIH-9& 12mo, 2 50 

* Bruff's Text-book of Ordnance and Gunnery Svo, 6 00 

Chase's Screw Propellers and Marine Propulsion Svo, 3 00 

Craig's Azimuth 4to, 3 50 

Crehore and Squire's Polarizing Photo-chronograph Svo, 3 00 

Cronkhite's Gunnery for Non-commissioned Officers.. 24m o, mor., 2 00 

* Da vis's Elements of Law. Svo. -1 .10 

* " Treatise on the Military Law of United States. . .Svo, 7 00 

Sheep, 7 50 

De Brack's Cavalry Outpost Duties. (Carr.) . . . .24mo, morocco, 2 00 

Dietz's Soldier's First Aid Handbook 16mo, morocco, 1 25 

* Dredge's Modern French Artillery 4to, half morocco, 15 00 

Durand's Resistance and Propulsion of Ships Svo, 5 00 

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Eissler's Modern High Explosives Svo, 4 00 

* Fiebeger's Text-book on Field Fortification Small Svo, 2 00 

* Hoff's Elementary Naval Tactics Svo, 1 50 

Ingalla's Handbook of Problems in Direct Fire Svo, 4 00 

* " Ballistic Tables Svo, 1 50 

Lyons's Treatise on Electromagnetic Phenomena Svo, 6 00 

*Mahan's Permanent Fortifications. (Mercur's.).Svo, half mor. 7 50 

Manual for Courts-martial 16mo, morocco, 1 50 

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" Elements of the Art of War Svo, 4 00 

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" Ordnance and Gunnery 12mo, 5 00 

Murray's Infantry Drill Regulations 18mo, paper, 10 

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Powell's Army Officer's Examiner 12mo, 4 00 



Sharpe's Art of Subsisting Armies in War 18mo, morocco, 1 50 

Walke's Lectures on Explosives 8vo, 4 00 

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Winthrop's Abridgment of Military Law 12mo, 2 50 

Woodhull's Notes on Military Hygiene 16mo, 1 50 

Young's Simple Elements of Navigation 16mo, morocco, 1 00 

Second Edition, Enlarged and Revised 16mo, mor., 2 00 

ASSAYING. 

Fletcher's Practical Instructions in Quantitative Assaying with 

the Blowpipe 12 mo , morocco, 1 50 

Furman's Manual of Practical Assaying 8vo, 3 00 

Miller's Manual of Assaying 12mo, 1 00 

O'Driscoll's Notes on the Treatment of Gold Ores 8vo, 2 00 

Ricketts and Miller's Notes on Assaying 8vo, 3 00 

Wilson's Cyanide Processes 12mo, 1 50 

" Chlorination Process 12mo, 1 50 

ASTRONOMY. 

Craig's Azimuth 4to, 3 50 

Doolittle's Treatise on Practical Astronomy. , 8vo, 4 00 

Gore's Elements of Geodesy . 8vo, 2 50 

Hayford's Text-book of Geodetic Astronomy 8vo, 3 00 

Merriman's Elements of Precise Surveying and Geodesy. . . .8vo, 2 50 

* Michie and Harlow's Practical Astronomy 8vo, 3 00 

* White's Elements of Theoretical and Descriptive Astronomy. 

12mo, 2 00 
BOTANY. 

Baldwin's Orchids of New England _ .... Small 8vo, 1 50 

Davenport's Statistical Methods, with Special Reference to Bio- 
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Thome" and Bennett's Structural and Physiological Botany. 

16rno, 2 25 

Westermaier's Compendium of General Botany. (Schneider.) 8 vo, 2 00 

CHEMISTRY. 

Adriance's Laboratory Calculations and Specific Gravity Tables, 

12mo, 1 25 

Allen's Tables for Iron Analysis 8vo, 3 00 

Arnold's Compendium of Chemistry. (Mandel.) (In preparation.) 

Austen's Notes for Chemical Students 12mo, 1 50 

Bernadou's Smokeless Powder. Nitro-cellulose, and Theory of 

the Cellulose Molecule 12mo, 2 50 

Bolton's Quantitative Analysis. 8vo, 1 50 

Brush and Penfield's Manual of Determinative Mineralogy.. 8 vo, 4 00 
Classen's Quantitative Chemical Analysis by Electrolysis. (Her- 

rick Boltwood.) 8vo, 3 00 



Cohn's Indicators and Test-papers 12mo, 2 00 

Craft's Short Course in Qualitative Chemical Analysis. (Schaef- 

fer.) 12mo, 2 00 

Drechsel's Chemical Reactions. (Merrill.) 12mo, 1 25 

Eissler's Modern High Explosives .' .8vo, 4 Oft 

Eff rent's Enzymes and their Applications. ( Prescott. ) (In preparation. ) 
Erdmann's Introduction to Chemical Preparations. (Dunlap.) 

12mo, 1 25 
Fletcher's Practical Instructions in Quantitative Assaying with 

the Blowpipe 12mo, morocco, 1 50 

Fresenius's Manual of Qualitative Chemical Analysis. (Wells.) 

8vo, 5 oa 

System of Instruction in Quantitative Chemical 

Analysis. (Allen.) 8vo, 600 

Fuertes's Water and Public Health 12mo, 1 50 

Furman's Manual of Practical Assaying 8vo, 3 00 

Gill's Gas and Fuel Analysis for Engineers 12mo, 1 25 

Grotenfelt's Principles of Modern Dairy Practice. ( Woll.) . . 12mo, 2 00 
Hammarsten's Text-book of Physiological Chemistry. (Mandel.) 

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Helm's Principles of Mathematical Chemistry. (Morgan.) . 12mo, 1 50 
Holleman's Text-book of Inorganic Chemistry. (Cooper.) 

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Hopkins's Oil-chemists' Handbook 8vo, 3 00 

Keep's Cdst Iron. (In preparation.) 

Ladd's Manual of Quantitative Chemical Analysis 12mo, 1 00 

Landauer's Spectrum Analysis. (Tingle.) 8vo, 3 00 

Lassar-Cohn's Practical Urinary Analysis. (Lorenz.) (In preparation.} 
Lob's Electrolysis and Electrosynthesis of Organic Compounds. 

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Mandel's Handbook for Bio-chemical Laboratory 12mo, 1 50 

Mason's Water-supply. (Considered Principally from a Sani- 
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" Examination of Water. (Chemical and Bacterio- 
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Meyer's Determination of Radicles in Carbon Compounds. 

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Miller's Manual of Assaying. 12mo, 1 00 

Mixter's Elementary Text-book of Chemistry 12mo, 1 50 

Morgan's Outline of Theory of Solution and its Results. . . 12mo, 1 00 

" Elements of Physical Chemistry 12mo, 2 00 

Nichols's Water-supply. (Considered mainly from a Chemical 

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O'Brine's Laboratory Guide in Chemical Analysis 8vo, 2 00 

O'Driscoll's Notes on the Treatment of Gold Ores 8vo, 2 00 

Ost and Kolbeck's Text-book of Chemical Technology. (Lor- 
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4 



* Penfield's Notes on Determinative Mineralogy and Record of 

Mineral Tests 8vo, paper, 50 

Pinner's Introduction to Organic Chemistry. (Austen.) . . . 12mo, 1 50 

Poole's Calorific Power of Fuels 8vo, 3 00 

* Reisig's Guide to Piece-dyeing 8vo, 25 00 

Richards and Woodman's Air, Water, and Food from a Sanitary 

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Richards's Cost of Living as Modified by Sanitary Science. 12mo, 1 00 

Cost of Food, a Study in Dietaries 12mo, 1 00 

Ricketts and Russell's Skeleton Notes upon Inorganic Chem- 
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Ricketts and Miller's Notes on Assaying 8vo, 3 00 

Rideal's Sewage and the Bacterial Purification of Sewage. .8vo, 3 50 

Ruddiman's Incompatibilities in Prescriptions 8vo, 2 00 

Schimpf's Text-book of Volumetric Analysis 12mo, 2 50 

Spencer's Handbook for Chemists of Beet-sugar Houses. 

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" Handbook for Sugar Manufacturers and their Chem- 
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Stockbridge's Rocks and Soils 8vo, 2 50 

* Tillman's Elementary Lessons in Heat 8vo, 1 50 

Descriptive General Chemistry 8vo, 3 00 

Turneaure and Russell's Public Water-supplies 8vo, 5 00 

Van Deventer's Physical Chemistry for Beginners. (Boltwood.) 

12mo, 1 50 

Walke's Lectures on Explosives 8vo, 4 00 

Wells's Laboratory Guide in Qualitative Chemical Analysis. 

..8vo, 1 50 

" Short Course in Inorganic Qualitative Chemical Analy- 
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Whipple's Microscopy of Drinking-water ; 8vo, 3 50 

Wiechmann's Sugar Analysis Small 8vo, 2 50 

" Lecture-notes on Theoretical Chemistry. . . .12mo, 3 00 

Wilson's Cyanide Processes 12mo, 1 50 

" Chlorination Process 12mo, 1 50 

Wulling's Elementary Course in Inorganic Pharmaceutical and 

Medical Chemistry 12mo, 2 00 

CIVIL ENGINEERING. 

BRIDGES AND ROOFS. HYDRAULICS. MATERIALS OF 
ENGINEERING. RAILWAY ENGINEERING. 

Baker's Engineers' Surveying Instruments 12mo, 3 00 

Bixby's Graphical Computing Table Paper, 19x24 inches. 25 

Davis's Elevation and Stadia Tables 8vo, 1 00 

Folwell's Sewerage. (Designing and Maintenance.) 8vo, 3 00 

Freitag's Architectural Engineering 8vo, 3 50 



Goodhue's Municipal Improvements 12mo, 1 75 

Goodrich's Economic Disposal of Towns' Refuse 8vo, 3 50 

Gore's Elements of Geodesy 8vo, 2 50 

Hayford's Text-book of Geodetic Astronomy .8vo, 3 00 

Howe's Retaining-walls for Earth 12mo, 1 25 

Johnson's Theory and Practice of Surveying Small 8vo, 4 00 

Stadia and Earth- work Tables 8vo, 1 25 

Kiersted's Sewage Disposal 12mo, 1 25 

Mahan's Treatise on Civil Engineering. (1873.) (Wood.) . .8vo, 500 

* Mahan's Descriptive Geometry 8vo, 1 50 

Merriman's Elements of Precise Surveying and Geodesy. . . .8vo, 2 50 

Merriman and Brooks's Handbook for Surveyors. . . ,16mo, mor., 2 00 

Merriman's Elements of Sanitary Engineering 8vo, 2 00 

Xugent's Plane Surveying. (In preparation.) 

Ogden's Sewer Design 12mo, 2 00 

Patton's Treatise on Civil Engineering 8vo, half leather, 7 50 

Reed's Topographical Drawing and Sketching 4to, 5 00 

Rideal's Sewage and the Bacterial Purification of Sewage . . 8vo, 3 50 

Siebert and Biggin's Modern Stone-cutting and Masonry . . 8vo, 1 50 

Smith's Manual of Topographical Drawing. (McMillan.) . .8vo, 2 50 

* Trautwine's Civil Engineer's Pocket-book. ... 16mo, morocco, 5 00 
Wait's Engineering and Architectural Jurisprudence 8vo, 6 00 

Sheep, 6 50 

" Law of Operations Preliminary to Construction in En- 
gineering and Architecture 8vo. 5 00 

Sheep, 5 50 

" Law of Contracts 8vo, 3 00 

Warren's Stereotomy Problems in Stone-cutting 8vo, 2 50 

Webb's Problems in the Use and Adjustment of Engineering 

Instruments 16mo, morocco, 1 25 

* Wheeler's Elementary Course of Civil Engineering 8vo, 4 00 

Wilson's Topographic Surveying 8vo, 3 50 

BRIDGES AND ROOFS. 

Boiler's Practical Treatise on the Construction of Iron Highway 

Bridges 8vo, 2 00 

* Boiler's Thames River Bridge 4to, paper, 5 00 

Burr's Course on the Stresses in Bridges and Roof Trusses, 

Arched Ribs, and Suspension Bridges 8vo, 3 50 

Du Bois's Stresses in Framed Structures Small 4to, 10 00 

Foster's Treatise on Wooden Trestle Bridges 4to, 5 00 

Fowler's Coffer-dam Process for Piers 8vo, 2 50 

Greene's Roof Trusses 8vo, 1 25 

" Bridge Trusses 8vo, 2 50 

" Arches in Wood. Iron, and Stone 8vo, 2 50 

Howe's Treatise on Arches Svo, 4 00 



Johnson, Biyan and Turneaure's Theory and Practice in the 

Designing of Modern Framed Structures Small 4to, 10 00 

Merriman and Jacoby's Text-book on Roofs and Bridges: 

Part I. Stresses in Simple Trusses 8vo, 2 50 

Part II. Graphic Statics 8vo, 2 00 

Part III. Bridge Design. Fourth Ed. (In preparation.} , .8vo, 250 

Part IV. Higher Structures 8vo, 2 50 

Morison's Memphis Bridge 4to, 10 00 

WaddelPs De Pontibus, a Pocket Book for Bridge Engineers. 

16mo, mor., 3 00 

Specifications for Steel Bridges 12mo, 1 25 

Wood's Treatise on the Theory of the Construction of Bridges 

and Roofs 8vo, 2 00 

Wright's Designing of Draw-spans: 

Part I. Plate-girder Draws 8vo, 2 50 

Part II. Riveted-truss and Pin-connected Long-span Draws. 

8vo, 2 50 

Two parts in one volume 8vo, 3 50 

HYDRAULICS. 

Bazin's Experiments upon the Contraction of the Liquid Vein 

Issuing from an Orifice. (Trautwine.) 8vo, 2 00 

Bovey's Treatise on Hydraulics 8vo, 5 00 

Church's Mechanics of Engineering 8vo, 6 00 

Coffin's Graphical Solution of Hydraulic Problems. . 16mo, mor., 2 50 

Flather's Dynamometers, and the Measurement of Power. 12mo, 3 00 

FQ! well's Water-supply Engineering 8vo, 4 00 

Frizell's Water-power 8vo, 5 00 

Fuertes's Water and Public Health 12mo, 1 50 

" Water-filtration Works 12mo, 2 50 

Ganguillet and Kutter's General Formula for the Uniform 
Flow of Water in Rivers and Other Channels. (Her- 

ing and Trautwine.) 8vo, 4 00 

Hazen's Filtration of Public Water-supply ^^ 8vo, 3 00 

Hazleurst's Towers and Tanks for Water-works 8vo, 2 50 

Herschel's 115 Experiments on the Carrying Capacity of Large, 

Riveted, Metal Conduits 8vo, 2 00 

Mason's Water-supply. (Considered Principally from a Sani- 
tary Standpoint.) 8vo, 5 00 

Merriman's Treatise on Hydraulics 8vo, 4 00 

* Michie's Elements of Analytical Mechanics 8vo, 4 00 

Schuyler's Reservoirs for Irrigation, Water-power, and Domestic 

Water-supply Large 8vo, 5 00 

Turneaure and Russell. Public Water-supplies 8vo, 5 00 

Wegmann's Design and Construction of Dams 4to, 5 00 

Water-supply of the City of New York from 1658 to 

1895 4k>, 10 00 

W T eisbach's Hydraulics and Hydraulic Motors. (Du Bois.) . .8vo, 5 00 

Wilson's Manual of Irrigation Engineering Small 8vo, 4 00 

Wolff's Windmill as a Prime Mover 8vo, 3 00 

Wood's Turbines 8vo, 2 50 

" Elements of Analytical Mechanics 8vo, 3 00 

MATERIALS OF ENGINEERING. 

Baker's Treatise on Masonry Construction 8vo, 500 

Black's United States Public Works Oblong 4to, 5 00 

Bovey's Strength of Materials and Theory of Structures. . . .8vo, 7 50 

7 



Burr's Elasticity and Resistance of the Materials of Engineer- 
ing , . . 8vo, 5 00 

Byrne's Highway Construction 8vo, 5 00 

" Inspection of the Materials and Workmanship Em- 
ployed in Construction 16mo, 3 00 

Church's Mechanics of Engineering 8vo, 6 00 

Du Bois's Mechanics of Engineering. Vol. I Small 4to, 10 00 

Johnson's Materials of Construction Large 8vo, 600 

Keep's Cast Iron. (In preparation.) 

Lanza's Applied Mechanics 8vo, 7 50 

Martens's Handbook on Testing Materials. (Henning.) 

2 vols., 8vo, 7 50 

Merrill's Stones for Building and Decoration '. . 8vo, 5 00 

Merriman's Text-book on the Mechanics of Materials 8vo, 4 00 

Merriman's Strength of Materials 12mo, 1 00 

Metcalf s Steel. A Manual for Steel-users 12mo, 2 00 

Patton's Practical Treatise on Foundations 8vo, 5 00 

Rockwell's Roads and Pavements in France 12mo, 1 25 

Smith's Wire: Its Use and Manufacture Small 4to, 3 00 

Spalding's Hydraulic Cement 12mo, 2 00 

Text-book on Roads and Pavements 12mo, 2 00 

Thurston's Materials of Engineering 3 Parts, 8vo, 8 00 

Part I. Non-metallic Materials of Engineering and Metal- 
lurgy 8vo, 2 00 

Part II. Iron and Steel 8vo, 3 50 

Part III. A Treatise on Brasses, Bronzes and Other Alloys 

and Their Constituents 8vo, 2 50 

Thurston's Text-book of the Materials of Construction 8vo, 5 00 

Tillson's Street Pavements and Paving Materials 8vo, 4 00 

WaddelFs De Pontibus. (A Pocket-book for Bridge Engineers.) 

16mo, morocco, 3 00 

Specifications for Steel Bridges 12mo, 1 25 

Wood's Treatise on the Resistance of Materials, and an Ap- 
pendix on the Preservation of Timber 8vo, 2 00 

" Elements of Analytical Mechanics 8vo, 3 00 

RAILWAY ENGINEERING, 

Berg's Buildings and Structures of American Railroads. .4to, 5 00 

Brooks's Handbook of Street Railroad Location. . 16mo, morocco, 1 50 

Butts's Civil Engineer's Field-book 16mo, morocco, 2 50 

CrandalPs Transition Curve 16mo, morocco, 1 50 

Railway and Other Earthwork Tables 8vo, 1 50 

Dawson's Electric Railways and Tramways . Small 4to, half mor., 12 50 
" "Engineering" and Electric Traction Pocket-book. 

16mo, morocco, 4 00 

Dredge's History of the Pennsylvania Railroad: (1879.) .Paper, 5 00 
* Drinker's Tunneling, Explosive Compounds, and Rock Drills. 

4to, half morocco, 25 00 

Fisher's Table of Cubic Yards Cardboard, 25 

Godwin's Railroad Engineers' Field-book and Explorers' Guide. 

16mo, morocco, 2 50 

Howard's Transition Curve Field-book 16mo, morocco, 1 50 

Hudson's Tables for Calculating the Cubic Contents of Exca- 
vations and Embankments 8vo, 1 00 

Nagle's Field Manual for Railroad Engineers. . . .16mo, morocco, 3 00 

PhSbrick's Field Manual for Engineers 16mo, morocco, 3 00 

Pratt and Alden's Street-railway Road-bed 8vo, 2 00 



Searles's Field Engineering ISrno, morocco, 3 00 

" Railroad Spiral 16mo, morocco, 1 50 

Taylor's Prismoidal Formulae and Earthwork 8vo, 1 50 

* Trautwine's Method of Calculating the Cubic Contents of Ex- 

cavations and Embankments by the Aid of Dia- 
grams 8vo, 2 00 

* The Field Practice of Laying Out Circular Curves 

for Railroads 12mo, morocco, 2 50 

* " Cross-section Sheet Paper, 25 

Webb's Railroad Construction 8vo, 4 00 

Wellington's Economic Theory of the Location of Railways. . 

Small 8vo, 5 00 



DRAWING. 

Barr's Kinematics of Machinery 8vo, 2 50 

* Bartlett's Mechanical Drawing .8vo, 3 00 

Durley's Elementary Text-book of the Kinematics of Machines. 

(In preparation.) 

Hill's Text-book on Shades and Shadows, and Perspective. . 8vo, 2 00 
Jones's Machine Design: 

Part I. Kinematics of Machinery ." 8vo, 1 50 

Part II. Form, Strength and Proportions of Parts 8vo, 3 00 

-MacCord's Elements of Descriptive Geometry 8vo, 3 00 

Kinematics; or, Practical Mechanism 8vo, 5 00 

Mechanical Drawing 4to, 4 00 

Velocity Diagrams 8vo, I 50 

* Mahan's Descriptive Geometry and Stone-cutting 8vo, 1 50 

Mahan's Industrial Drawing. (Thompson.) 8vo, 3 50 

Reed's Topographical Drawing and Sketching 4to, 5 00 

Reid's Course in Mechanical Drawing 8vo, 2 00 

" Text-book of Mechanical Drawing and Elementary Ma- 
chine Design 8vo, 3 00 

Robinson's Principles of Mechanism 8vo, 3 00 

Smith's Manual of Topographical Drawing. (McMillan.) .8vo, 2 50 
Warren's Elements of Plane and Solid Free-hand Geometrical 

Drawing 12mo, 1 00 

Drafting Instruments and Operations 12mo, 1 25 

Manual of Elementary Projection Drawing 12mo, 1 50 

" Manual of Elementary Problems in the Linear Per- 
spective of Form and Shadow 12mo, 1 00 

" Plane Problems in Elementary Geometry 12mo, 1 25 

" Primary Geometry 12mo, 75 

" Elements of Descriptive Geometry, Shadows, and Per- 
spective 8vo, 3 50 

General Problems of Shades and Shadows 8vo, 3 00 

Elements of Machine Construction and Drawing. .8vo, 7 50 
" Problems, Theorems, and Examples in Descriptive 

Geometry 8vo, 2 50 

Weisbach's Kinematics and the Power of Transmission. (Herr- 
mann and Klein.) 8vo, 5 00 

Whelpley's Practical Instruction in the Art of Letter En- 
graving 12mo, 2 00 

Wilson's Topographic Surveying 8vo, 3 50 

Wilson's Free-hand Perspective 8vo, 2 50 

Woolf's Elementary Course in Descriptive Geometry. . Large 8vo, 3 00 



ELECTRICITY AND PHYSICS. 

Anthony and Brackett's Text-book of Physics. (Magie.) 

Small 8vo. 3 00 
Anthony's Lecture-notes on the Theory of Electrical- Measur- 

ments " 12mo. 1 00 

Benjamin's History of Electricity 8vo. 3 00 

Benjamin's Voltaic Cell Svo. 3 00 

Classen's Qantitative Chemical Analysis by Electrolysis. Her- 

rick and Boltwood.) ". 8vo. 3 00 

Crehore and Squier's Polarizing Photo-chronograph Svo. .3 00 

Dawson's Electric Railways and Tramways..Small 4to, half mor.. 12 50 
Dawson's " Engineering " and Electric Traction Pocket-book. 

16mo, morocco, 4 00 

Flather's Dynamometers, and the Measurement of Power. . 12mo. 3 00 

Gilbert's De Magnete. (Mottelay.) Svo, 2 50 

Holman's Precision of Measurements Svo, 2 00 

Telescopic Mirror-scale Method, Adjustments, and 

Tests Large Svo. 75 

Landauer's Spectrum Analysis. (Tingle.) -. Svo, 3 00 

Le Chatelier's High-temperature Measurements. (Boudouard 

Burgess.) 12mo. 3 00 

Lob's Electrolysis and Electrosynthesis of Organic Compounds. 

(Lorenz.) ". 12mo. 1 00 

Lyons's Treatise on Electromagnetic Phenomena Svo, 6 00 

* Michie. Elements of Wave Motion Relating to Sound and 

Light Svo. 4 00 

Niaudet's Elementary Treatise on Electric Batteries (Fish- 
back.) 12mo. 2 50 

* Parshall and Hobart's Electric Generators-Small 4ta, half mor., 10 00 
Thurston's Stationary Steam-engines Svo. 2 50 

* Tillman. Elementary Lessons in Heat Svo, 1 50 

Tory and Pitcher. Manual of Laboratory Physics. .Small Svo. 2 00 

LAW. 

* Davis. Elements of Law Svo. 2 50 

* " Treatise on the Military Law of United States. .Svo, 7 00 

Sheep, 7 50 

Manual for Courts-martial IGmo, morocco, 1 50 

Wait's Engineering and Architectural Jurisprudence Svo, 6 00 

Sheep, 6 50 

" Law of Operations Preliminary to Construction in En- 
gineering and Architecture ; < Svo, 5 00 

Sheep, 5 50 

" Law of Contracts Svo, 3 00 

Winthrop's Abridgment of Military Law 12mo, 2 50 

MANUFACTURES. 

Beaumont's Woollen and Worsted Cloth Manufacture. .. .12mo. 1 50 
Bernadou's Smokeless Powder Nitro-cellulose and Theory of 

the Cellulose Moleeule f2mo, 2 50 

Bolland's Iron Founder 12mo, cloth, - "><> 

" The Iron Founder " Supplement 12mo, 2 50 

" Encyclopedia of Founding and Dictionary of Foundry 

Terms Used in the Practice of Moulding. .. . 12mo. 3 00 

Eissler's Modern High Explosives Svo, 4 00 

Effront's Enzymes and their Applications. (Prescott.) (In preparation.) 

Fitzgerald's Boston Machinist ISmo, 1 00 

10 



Ford's Boiler Making for Boiler Makers 18mo, 100 

Hopkins's Oil-chemists' Handbook Svo, 3 00 

Keep's Cast Iron. (In preparation.) 

Metcalf s Steel. A Manual for Steel-users 12mo, 2 00 

Metcalf's Cost of Manufactures And the Administration of 

Workshops, Public and Private Svo, 5 00 

Meyer's Modern Locomotive Construction . 4to, 10 00 

* Reisig's Guide to Piece-dyeing Svo, 25 00 

Smith's Press-working of Metals 8vo, 3 00 

" Wire: Its Use and Manufacture Small 4to, 3 00 

Spalding's Hydraulic Cement 12mo, 2 00 

Spencer's Handbook for Chemists of Beet-sugar Houses. 

16mo, morocco, 3 00 

Handbook for Sugar Manufacturers and their Chem- 
ists 16mo, morocco, 2 00 

Thurston's Manual of Steam-boilers, their Designs, Construc- 
tion and Operation 8vo, 5 00 

Walke's Lectures on Explosives 8vo, 4 00 

West's American Foundry Practice 12mo, 2 50 

" Moulder's Text-book 12mo, 2 50 

Wiechmann's Sugar Analysis Small 8vo, 2 50 

Wolff's Windmill as a Prime Mover 8vo, 3 00 

Woodbury's Fire Protection of Mills 8vo, 2 50 



MATHEMATICS. 

Baker's Elliptic Functions 8vo, 1 50 

* Bass's Elements of Differential Calculus 12mo, 4 00 

Briggs's Elements of Plane Analytic Geometry 12mo. 1 00 

Chapman's Elementary Course in Theory of Equations.. .12mo, 1 50 

Compton's Manual of Logarithmic Computations... 12mo, I 50 

Da vis's Introduction to the Logic of Algebra 8vo, 1 59 

Halsted's Elements of Geometry Svo, 1 75 

Elementary Synthetic Geometry 777 Svo, 1 50 

Johnson's Three- place Logarithmic Tables : Vest-pocket size, pap., 15 

100 copies for 5 00 

Mounted on heavy cardboard, 8 X 10 inches, 25 

10 copies for 2 00 
Elementary Treatise on the Integral Calculus. 

Small Svo, 1 50 

Curve Tracing in Cartesian Co-ordinates 12mo, 1 00 

" Treatise on Ordinary and Partial Differential 

Equations Small Svo, 3 50 

Theory of Errors and the Method of Least 

Squares 12mo, 1 50 

Theoretical Mechanics , ... 12mo, 3 00 

* Ludlow and Bass. Elements of Trigonometry and Logarith- 

mic and Other Tables Svo, 3 00 

Trigonometry. Tables published separately. .Each, 2 00 

Merriman and Woodward. Higher Mathematics Svo, 5 00 

Merriman's Method of Least Squares Svo, 2 00 

Rice and Johnson's Elementary Treatise on the Differential 

Calculus Small Svo, 3 00 

Differential and Integral Calculus. 2 vols. 

in one Small Svo, 2 50 

Wood's Elements of Co-ordinate Geometry Svo, 2 00 

" Trigometry: Analytical, Plane, and Spherical. .. .12mo, 1 00 

11 



MECHANICAL ENGINEERING. 

MATERIALS OF ENGINEERING, STEAM ENGINES 
AND BOILERS. 

Baldwin's Steam Heating for Buildings 12mo, 2 50 

Barr's Kinematics of Machinery 8vo, 2 50 

* Bartlett's Mechanical Drawing 8vo, 3 00 

Benjamin's Wrinkles and Recipes 12mo, 2 00 

Carpenter's Experimental Engineering 8vo, 6 00 

Heating and Ventilating Buildings 8vo, 3 00 

Clerk's Gas and Oil Engine Small 8vo, 4 00 

Cromwell's Treatise on Toothed Gearing 12mo, 1 50 

Treatise on Belts and Pulleys 12mo, 1 50 

Durley's Elementary Text-book of the Kinematics of Machines. 

(In preparation.) 

Flather's Dynamometers, and the Measurement of Power . . 12mo, 3 00 

" Rope Driving 12mo, 2 00 

Gill's Gas an Fuel Analysis for Engineers 12mo, 1 25 

Hall's Car Lubrication 12mo, 1 00 

Jones's Machine Design: 

Part I. Kinematics of Machinery 8vo, 1 50 

Part II. Form, Strength and Proportions of Parts 8vo, 3 09 

Kent's Mechanical Engineers' Pocket-book. .. .16mo, morocco, 5 00 
Kerr's Power and Power Transmission. (In preparation.) 

MacCord's Kinematics ; or, Practical Mechanism 8vo, 5 00 

Mechanical Drawing 4to, 4 00 

Velocity Diagrams 8vo, 1 50 

Mahan's Industrial Drawing. (Thompson.) 8vo, 3 50 

Pople's Calorific Power of Fuels 8vo, 3 00 

Reid's Course in Mechanical Drawing 8vo, 2 00 

" Text-book of Mechanical Drawing and Elementary 

Machine Design 8vo, 3 00 

Richards's Compressed Air 12mo, 1 50 

Robinson's Principles of Mechanism 8vo, 3 00 

Smith's Press-working of Metals 8vo, 3 00 

Thurston's Treatise on Friction and Lost Work in Machin- 
ery and Mill Work 8vo, 3 00 

Animal as a Machine and Prime Motor and the 

Laws of Energetics 12mo, 1 00 

Warren's Elements of Machine Construction and Drawing. .8vo, 7 50 
Weisbach's Kinematics and the Power of Transmission. (Herr- 
mannKlein.) 8vo, 5 00 

" Machinery of Transmission and Governors. (Herr- 
mannKlein.) i '. 8vo, 5 00 

Hydraulics and Hydraulic Motors. (Du Bois.) .8vo, 5 00 

Wolff's Windmill as a Prime Mover '. 8vo, 3 00 

Wood's Turbines 8vo, 2 50 

MATERIALS OF ENGINEERING. 

Bovey's Strength of Materials and Theory of Structures. .8 vo, 7 50 
Burr's Elasticity and Resistance of the Materials of Engineer- 
ing 8vo, 5 00 

Church's Mechanics of Engineering 8vo, 6 00 

Johnson's Materials of Construction Large 8vo, 6 00 

Keep's Cast Iron. (In preparation.) 

Lanza's Applied Mechanics 8vo, 7 50 

Martens's Handbook on Testing Materials. (Henning.) . . . .8vo, 7 50 

Merriman'd Text-book on the Mechanics of Materials .... 8vo, 4 00 

Strength of Materials 12mo, 1 00 

12 



Metcalf's Steel. A Manual for Steel-users 12mo, 2 00 

Smith's Wire: Its Use and Manufacture Small 4to, 3 00 

Thurston's Materials of Engineering 3 vols., 8vo, 8 00 

Part II. Iron and Steel 8vo, 3 50 

Part III. A Treatise on Brasses, Bronzes and Other Alloys 

and their Constituents 8vo, 2 50 

Thurston's Text-book of the Materials of Construction. .. .8vo, 5 00 
Wood's Treatise on the Resistance of Materials and an Ap- 
pendix on the Preservation of Timber 8vo, 2 00 

" Elements of Analytical Mechanics 8vo, 3 00 

STEAM ENGINES AND BOILERS. 

Carnot's Reflections on the Motive Power of Heat. (Thurston.) 

12mo, 1 50 
Dawson's " Engineering " and Electric Traction Pocket-book. 

16mo, morocco, 4 00 

Ford's Boiler Making for Boiler Makers 18mo, 1 00 

Hemenway's Indicator Practice and Steam-engine Economy. 

12mo, 2 00 

Hutton's Mechanical Engineering of Power Plants 8vo, 5 00 

" Heat and Heat-engines 8vo, 5 00 

Kent's Steam-boiler Economy 8vo, 4 00 

Kneass's Practice and Theory of the Injector 8vo, 1 50 

MacCord's Slide-valves 8vo, 2 00 

Meyer's Modern Locomotive Construction 4to, 10 00 

Peabody's Manual of the Steam-engine Indicator 12mo, 1 50 

Tables of the Properties of Saturated Steam and 

Other Vapors 8vo, 1 00 

" Thermodynamics of the Steam-engine and Other 

Heat-engines 8vo, 5 00 

Valve-gears for Steam-engines 8vo, 2 50 

Peabody and Miller. Steam-boilers 8vo, 4 00 

Pray's Twenty Years with the Indicator Large 8vo, 2 50 

Pupin's Thermodynamics of Reversible Cycles in Gases and 

Saturated Vapors. (Osterberg.) 12mo, 1 25 

Reagan's Locomotive Mechanism and Engineering 12mo, 2 00 

Rontgen's Principles of Thermodynamics. (Du Bois.) . . . .8vo, 5 00 

Sinclair's Locomotive Engine Running and Management. . 12mo, 2 00 

Smart's Handbook of Engineering Laboratory Practice. .12mo, 2 50 

Snow's Steam-boiler Practice 8vo, 3 00 

Spangler's Valve-gears 8vo, 2 50 

Notes on Thermodynamics 12mo, 1 00 

Thurston's Handy Tables 8vo, 1 50 

Manual of the Steam-engine 2 vols., 8vo, 10 00 

Part I. History, Structure, and Theory 8vo, 6 00 

Part II. Design, Construction, and Operation 8vo, 6 00 

Thurston's Handbook of Engine and Boiler Trials, and the Use 

of the Indicator and the Prony Brake 8vo, 5 00 

Stationary Steam-engines 8vo, 2 50 

Steam-boiler Explosions in Theory and in Prac- 
tice 12mo, 1 50 

Manual of Steam-boilers, Their Designs, Construc- 
tion, and Operation 8vo, 5 00 

Weisbach's Heat, Steam, and Steam-engines. (Du Bois.). .8vo, 5 00 

Whitham's Steam-engine Design 8vo, 5 00 

Wilson's Treatise on Steam-boilers- (Flather.) 16mo, 2 50 

Wood's Thermodynamics, Heat Motors, and Refrigerating 

Machines 8vo, 4 00 

13 



MECHANICS AND MACHINERY. 

Barr's Kinematics of Machinery 8vo, 2 50 

Bovey's Strength of Materials and Theory of Structures. .8vo, 7 50 

Chordal. Extracts from Letters 12mo, 2 00 

Church's Mechanics of Engineering Svo, 6 00 

Notes and Examples in Mechanics Svo, 2 00 

Coinpton's First Lessons in Metal-working 12mo, 1 50 

Compton and De Groodt. The Speed Lathe 12mo, 1 50 

Cromwell's Treatise on Toothed Gearing 12mo, 1 50 

Treatise on Belts and Pulleys 12mo, 1 50 

Dana's Text-book of Elementary Mechanics for the Use of 

Colleges and Schools 12ma, 1 50 

Dingey's Machinery Pattern Making 12mo, 2 00 

Dredge's Record of the Transportation Exhibits Building of the 

World's Columbian Exposition of 1893 4to, half mor., 5 00 

Du Bois's Elementary Principles of Mechanics: 

Vol. I. Kinematics Svo, 3 50 

Vol. II. Statics 8vo, 4 00 

Vol. III. Kinetics Svo, 3 50 

Du Bois's Mechanics of Engineering. Vol. I Small 4to, 10 00 

Durley's Elementary Text-book of the Kinematics of Machines. 

(In preparation.) 

Fitzgerald's Boston Machinist 16mo, 1 00 

Flather's Dynamometers, and the Measurement of Power. 12mo, 3 00 

" Rope Driving 12mo, 2 00 

Hall's Car Lubrication 12mo, 1 00 

Holly's Art of Saw Filing 18mo, * 75 

* Johnson's Theoretical Mechanics 12mo, 3 00 

Jones's Machine Design: 

Part I Kinematics of Machinery Svo, 1 50 

Part II. Form, Strength and Proportions of Parts. .. .Svo, 3 00 
Kerr's Power and Power Transmission. (In preparation.) 

Lanza's Applied Mechanics Svo, 7 50 

MacCord's Kinematics; or, Practical Mechanism Svo, 5 00 

" Velocity Diagrams Svo, 1 50 

Merriman's Text-book on the Mechanics of Materials Svo, 4 00 

* Michie's Elements of Analytical Mechanics Svo, 4 00 

Reagan's Locomotive Mechanism and Engineering 12mo, 2 00 

Reid's Course in Mechanical Drawing Svo, 2 00 

" Text-book of Mechanical Drawing and Elementary 

Machine Design Svo, 3 00 

Richards's Compressed Air 12mo, 1 50 

Robinson's Principles of Mechanism Svo, 3 00 

Sinclair's Locomotive-engine Running and Management. .12mo, 2 00 

Smith's Press- working of Metals Svo, 3 00 

Thurston's Treatise on Friction and Lost Work in Machin- 
ery and Mill Work Svo, 3 00 

Animal as a Machine and Prime Motor, and the 

Laws of Energetics 12mo, 1 00 

Warren's Elements of Machine Construction and Drawing. .Svo, 7 50 
Weisbach's Kinematics and the Power of Transmission. 

(Herrman Klein.) Svo, 5 00 

" Machinery of Transmission and Governors. (Herr- 

(man Klein.) Svo, 5 00 

Wood's Elements of Analytical Mechanics Svo, 3 00 

" Principles of Elementary Mechanics 12mo, 1 25 

" Turbines Svo, 2 50 

The World's Columbian Exposition of 1893 4to, 1 00 

14 



METALLURGY. 

Idlest on's Metallurgy of Silver, Gold, and Mercury: 

Vol. I Silver 8vo, 7 50 

Vol. II. Gold and Mercury 8vo, 7 50 

Keep's Cast Iron. (In preparation.) 

Kunhardt's Practice of Ore Dressing in Lurope 8vo, 1 50 

Le Chatelier's High-temperature Measurements. (Boudouard 

Burgess.) 12mo, 3 00 

Metcalf's Steel. A Manual for Steel-users 12mo, 2 00 

Thurston's Materials of Engineering. In Three Parts 8vo, 8 00 

Part II. Iron and Steel 8vo, 3 50 

Part III. A Treatise on Brasses, Bronzes and Other Alloys 

and Their Constituents 8vo, 2 50 

MINERALOGY. 

Barringer's Description of Minerals of Commercial Value. 

Oblong, morocco, 2 50 

Boyd's Resources of Southwest Virginia 8vo, 3 00 

" Map of Southwest Virginia Pocket-book form, 2 00 

Brush's Manual of Determinative Mineralogy. (Penfield.) .8vo, 4 00 

Chester's Catalogue of Minerals 8vo, paper, 1 00 

Cloth, 1 25 

Dictionary of the Names of Minerals 8vo, 3 50 

Dana's System of Mineralogy Large 8vo, half leather, 12 50 

" First Appendix to Dana's New " System of Mineralogy." 

Large 8vo, 1 00 

Text-book ftf Mineralogy 8vo, 4 00 

Minerals and How to Study Them 12mo, 1 50 

Catalogue of American Localities of Minerals . Large 8vo, 1 00 

" Manual of Mineralogy and Petrography 12mo, 2 00 

Egleston's Catalogue of Minerals and Synonyms 8vo, 2 50 

Hussak's The Determination of Rock-forming Minerals. 

(Smith.) Small 8vo, 2 00 

* Penfield's Notes on Determinative Mineralogy and Record of 

Mineral Tests . . ; 8vo, paper, 50 

Rosenbusch's Microscopical Physiography of the Rock-making 

Minerals. (Idding's.) .8vo, 500 

* Tillman's Text-book of Important Minerals and Rocks . . 8vo, 2 00 
Williams's Manual of Lithology 8vo, 3 00 

MINING. 

Beard's Ventilation of Mines 12mo, 2 50 

Boyd's Resources of Southwest Virginia 8vo, 3 00 

" Map of Southwest Virginia Pocket-book form, 2 00 

* Drinker's Tunneling, Explosive Compounds, and Rock 

Drills 4to, half morocco, 25 00 

Eissler's Modern High Explosives 8vo, 4 00 

Goodyear's Coal-mines of the Western Coast of the United 

States 12mo, 250 

Ihlseng's Manual of Mining 8vo, 4 00 

Kunhardt's Practice of Ore Dressing in Europe 8vo, 1 50 

O'Driscoll's Notes on the Treatment of Gold Ores 8vo, 2 00 

Sawyer's Accidents in Mines 8vo, 7 00 

Walke's Lectures on Explosives 8vo, 4 00 

Wilson's Cyanide Processes 12mo, 1 50 

Wilson's Chlorination Process 12mo, 1 50 

15 



Wilson's Hydraulic and Placer Mining 12uio, 2 00* 

Wilson's Treatise on Practical and Theoretical Mine Ventila- 
tion 12mo, 1 25 

SANITARY SCIENCE. 

Fol well's Sewerage. (Designing, Construction and Maintenance.) 

8vo, 3 0(V 

Water-supply Engineering 8vo, 4 00 

Fuertes's Water and Public Health 12mo, 1 50 

Water-filtration Works 12mo, 2 50 

Gerhard's Guide to Sanitary House-inspection 16mo, 1 00 

Goodrich's Economical Disposal of Towns' Refuse. . .Demy 8vo, 3 50 

Hazen's Filtration of Public Water-supplies 8vo, 3 00 

Kiersted's Sewage Disposal 12mo, 1 25 

Mason's Water-supply. (Considered Principally from a San- 
itary Standpoint 8vo, 5 00 

" Examination of Water. (Chemical and Bacterio- 
logical.) 12mo, 1 25 

Merriman's Elements of Sanitary Engineering 8vo, 2 00 

Nichols's Water-supply. (Considered Mainly from a Chemical 

and Sanitary Standpoint.) (1883.) 8vo, 2 50 

Ogden's Sewer Design 12mo, 2 00 

Richards's Cost of Food. A Study in Dietaries 12mo, 1 OO 

Richards and Woodman's Air, Water, and Food from a Sani- 
tary Standpoint 8vo, 2 00 

Richards's Cost of Living as Modified by Sanitary Science . 12mo, 1 00 

Rideal's Sewage and Bacterial Purification of Sewage 8vo, 3 50- 

Turneaure and Russell's Public Water-supplies 8vo, 5 00 

Whipple's Microscopy of Drinking-water 8vo, 3 50 

Woodhull's Notes on Military Hygiene 16mo, 1 5Q 

MISCELLANEOUS. 

Barker's Deep-sea Soundings 8vo, 2 00 

Emmons's Geological Guide-book of the Rocky Mountain Ex- 
cursion of the International Congress of Geologists. 

Large 8vo, 1 50 

FerreFs Popular Treatise on the Winds 8vo, 4 00 

Haines's American Railway Management 12mo, 2 50 

Mott's Composition, Digestibility, and Nutritive Value of Food. 

Mounted chart, 1 25 

" Fallacy of the Present Theory of Sound 16ma, 1 00 

Ricketts's History of Rensselaer Polytechnic Institute, 1824- 

1894 Small 8vo, 3 00 

Rotherham's Emphasised New Testament Large 8vo, 2 00 

" Critical Emphasised New Testament 12mo, 1 50 

Steel's Treatise on the Diseases of the Dog 8vo, 3 50 

Totten's Important Question in Metrology 8vo, 2 5Q 

The World's Columbian Exposition of 1893 4to, 1 00 

Worcester and Atkinson. Small Hospitals, Establishment and 
Maintenance, and Suggestions for Hospital Architecture, 

with Plans for a Small Hospital 12mo, 1 25- 

HEBREW AND CHALDEE TEXT-BOOKS. 

Green's Grammar of the Hebrew Language 8vo, 3 00 

" Elementary Hebrew Grammar 12mo, 1 25 

" Hebrew Chrestomathy 8vo, 2 00 

Gesenius's Hebrew and Chaldee Lexicon to the Old Testament 

Scriptures. (Tregelles.) Small 4to, half morocco, 5 00 

Letteris's Hebrew Bible 8vo, 2 25 

16 



YC 32865 



785375 



gineering 
Library 



UNIVERSITY OF CALIFORNIA LIBRARY