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Bulletin No. 213
Series A, Economic Geology, 24
DEPARTMENT OF THE INTERIOR
UNITED STATES GEOLOGICAL SURVEY
CHARLES D. WALCOTT, Director
CONTRIBUTIONS
ECONOMIC GEOLOGY
19 0 2
S. F. EMMONS
C. W. HAYES
Greologists in. Charge
WASHINGTON
GOVERNMENT PRINTING OFFICE
1 9 0 3
e 0 N T E NTS.
Page.
Letter of transmittal 7
Introduction, by C. W. Hayes 9
Investigation of metalliferous ores, by S. F. Emmons 15
Investigation of nonmetalliferous economic minerals, "by C. W. Hayes 29
Gold and silver 31
Progress report on Park City mining district, Utah, by J. M. Boutwell 31
Placer gold mining in Alaska in 1902, by Alfred H. Brooks . , 41
The Glenn Creek gold-mining district, Alaska, by Arthur J. Collier 49
Gold and pyrite deposits of the Dahlonega district, Georgia, by Edwin
C.Eckek _._ 57
Neocene rivers of the Sierra Nevada, by Waldemar Lindgren (54
Mineral deposits of the Bitterroot Range and the Clearwater Moun-
tains, Montana, by Waldemar Lindgren 66
The Chistochina gold field, Alaska, by Walter C. Mendenhall . 71
Gold mining in central Washington, by George Otis Smith . . 76
Ore deposits of Tonopah and neighboring districts, Nevada, by J. E.
Spurr 81
Gold mines of the Marysville district, Montana, by Walter Harvey
Weed 88
List of Survey publications on gold and silver 90
Quicksilver, platinum, tin, tungsten, chromium, and nickel 92
Stream tin in Alaska, by Alfred H. Brooks 92
Platinum in copper ores in Wyoming, by S. F. Emm< >ns 94
Tungsten mining at Trumbull, Conn., by W. H. Hobbs. 98
Tin deposits at El Paso, Tex. , by Walter Harvey Weed . 99
Tungsten ore in eastern Nevada, by F. B. Weeks 103
List of Survey publications on quicksilver, platinum, tin, tungsten,
chromium, and nickel . - 104
Copper 1 05
Ore deposits of Bingham , Utah, by J M. Boutwell 1 05
Copper deposits of the Redding district, California, by J. S. Diller. 123
Copper deposits at Clifton, Ariz. , by Waldemar Lindgren 1 33
Copper deposits of the Mount Wrangell region, Alaska, by Walter C.
Mendenhall and Frank C. Schrader 141
Copper deposits of Bisbee, Ariz. , by F. L. Ransome 149
Mineral resources of the Encampment copper region, Wyoming, by
Arthur C. Spencer 158
Reconnaissance examination of the copper deposits at Pearl, Colo., by
Arthur C. Spencer 163
Ore deposits at Butte, Mont. , by Walter Harvey Weed 170
Copper deposits of the Appalachian States, by Walter Harvey Weed... 181
List of publications on copper _ 186
4 CONTENTS.
Page.
Lead and zinc •. - 1 87
Zinc and lead deposits of northern Arkansas, by George I. Adams 187
Lead and zinc deposits of the Joplin district, Missouri-Kansas, by W. S.
Tangier Smith 1 97
Lead, zinc, and fluorspar deposits of western Kentucky, by E. O. Ulrich
and W. S. Tangier Smith 205
Zinc and manganese deposits of Franklin Furnace, N. J. , by J. E. Wolff _ 214
List of Survey publications on lead and zinc 218
Iron and manganese 219
Iron ores of the Redding quadrangle, California, by J. S. Diller 219
Utilization of iron and steel slags, by Edwin C. Eckel 221
Manganese ores of the Cartersville district, Georgia, by C. W. Hayes. 232
Iron ores of the Cartersville district, Georgia, by C. W. Hayes and
Edwin C. Eckel 233
Iron-ore deposits of the Cranberry district. North Carolina-Tennessee,
by Arthur Keith 243
Geologic work in the Lake Superior iron district during 1902, by C. K.
Leith 247
Manganese deposits of Santiago, Cuba, by Arthur C. Spencer 251
List of publications on iron and manganese 256
Coal 257
Coal fields of the United States, by C. W. Hayes 257
Recent work in the bituminous coal field of Pennsylvania, by M. R.
Campbell 270
Coal resources of the Yukon Basin, Alaska, by Arthur J. Collier 276
Recent work in the coal field of Indiana and Illinois, by Myron L.
Fuller and George H. Ashley 284
List of Survey publications on coal, lignite, and peat 294
Oil, gas, and asphalt 296
Origin and distribution of asphalt and bituminous rock deposits in the
United States, by George H. Eldridge 296
The petroleum fields of California by George H. Eldridge 306
The Boulder, Colo. , oil field, by N. M. Fenneman 322
Asphalt, oil, and gas in southwestern Indiana, by Myron L. Fuller 333
Structural work during 1901 and 1902 in the eastern Ohio oil fields, by
W. T. Griswold 336
Oil fields of the Texas-Louisiana Gulf Coastal Plain, by C. W. Hayes, . 345
Asphalt deposits of Pike County, Ark. , by C. W. Hayes 353
List of publications on oil, gas, and asphalt 356
Stone 357
The stone industry in the vicinity of Chicago, 111. , by William C. Alden_ 357
The slate industry at Slatington, Pa., and Martinsburg, W. Va., by
T. Nelson Dale 361
Limestone of the Redding district, California, by J. S. Diller 365
Tennessee marbles, by Arthur Keith 366
List of Survey publications on stone 371
Cements _ 372
Cement investigations in Arizona, by Edward Duryee 372
List of xuiblications on cements 381
Clays and fuller's earth 382
Stoneware and brick clays of western Tennessee and northwestern
Mississippi, by Edwin C. Eckel 382
Fuller 's-earth deposits of Florida and Georgia, by T. Wayland Vaughan
List of Survey publications on clays, fuller's earth, etc
392
400
CONTENTS. 5
Page.
Gypsum, salt, borax, and soda 401
Borax deposits of eastern California, by M. R. Campbell - 401
Salt and gypsum deposits of southwestern Virginia, by Edwin C.
Eckel _ . . 406
List of Survey publications on gypsum, salt, borax, and soda 417
Pli< >sphates and other mineral fertilizers 418
Origin and extent of the Tennessee white phosphates, by C. W. Hayes- 418
The white phosphates of Decatur County, Tenn., by Edwin C. Eckel _ . 424
List of publications on phosphates and other mineral fertilizers 426
Mineral paints 427
Occurrence and development of ocher deposits in the Cartersville dis-
trict, Georgia, by C. W. Hayes and Edwin C. Eckel. . 427
Talc 433
Talc deposits of North Carolina, by Arthur Keith 433
Miscellaneous nonmetalliferous mineral products 439
Index 441
Digitized by the Internet Archive
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http://archive.org/details/bulletinofunited213emmo
LETTER OF TRANSMITTAL.
Department of the Interior,
United States Geological Survey,
Washington, D. C, March 9, 1903.
Sir: I have the honor to transmit, for publication as a bulletin of
the Survey, a manuscript entitled Contributions to Economic Geology,
1002.
The report contains 61 contributions from X'} members of the Survey
who have been engaged more or less continuously throughout the year
in economic work, together with a brief statement bj~ the geologists in
charge of the sect ion of metalliferous ores and the section of non-
metalliferous economic minerals, of the extent and character of the
economic work being carried on in the Survey.
Very respectfully,
C. W. Hayes,
Geologist in Charge of Geology.
Hon. Charles I). Walcott,
Director United States Geological Surrey.
CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902.
S. F. Emmons,
C. W. Hayes,
Geologists in Charge.
INTRODUCTION.
By C. W. Hayes, Geologist in Charge of Geology.
This bulletin has been prepared primarily with a view to securing
prompt publication of the economic results of investigations by the
United States Geological Survey. It is designed to meet the wants of
the busy man, and is so condensed that he will be able to obtain
results and conclusions with a minimum expenditure of time and
energy. It also affords a better idea of the work which the Survey as
an organization is carrying on for the direct advancement of mining
interests throughout the country than can readily be obtained from
the more voluminous reports. Should this bulletin be favorably
received by those interested in the development of the mineral indus-
tries of the United States, it is proposed to publish early in each cal-
endar year a similar bulletin containing the results of the last year's
field work in economic geology.
In the preparation of the present volume, promptness of publica-
tion has been made secondary only to the economic utility of the
material presented. The papers included are such only as have a
direct economic bearing, all questions of purely scientific interest
being excluded.
The papers represent three classes: (1) Preliminary discussions of
the results of extended economic investigations, which will later be
published by the Survey in more detailed form; (2) comparatively
detailed descriptions of occurrences of economic interest, noted by
geologists of the Survey in the course of their field work, but not of
sufficient importance to necessitate a later and more extended descrip-
tion; (3) abstracts of certain economic papers which have appeared
in Survey publications during the last year, chiefly such as give a
general account of the distribution and mode of occurrence of
particular mineral deposits throughout the United States.
The papers have been grouped according to the subjects treated.
At the end of each section is given a list of previous publications on
that subject by this Survey. These lists will be found serviceable by
those who wisli to ascertain what has been accomplished by the Sur-
9
10 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 11)02. [bull. 213.
vey in the investigation of any particular group of mineral products.
They are generally confined to Survey publications, though a few
titles of important papers published elsewhere by members of the
Survey are included.
The results of the Survey work in economic geology have been
published in a number of different forms, which are here briefly
described :
1. Papers and reports accompanying the Annual Report of the
Director, United States Geological Survey. — Prior to the present year
many economic reports were published in the ro}^al octavo cloth-bound
volumes which accompanied the Annual Report of the Director.
This form of publication for scientific papers has been discontinued
and a new series, termed Professional Papers, substituted.
2. Bulletins of the United Slides Geological Survey. — The bulletins
of the Snrve}T comprise a series of paper-covered octavo volumes,
each in general containing a single report or paper. These bulletins,
formerly sold at nominal prices, are now distributed free of charge t
those interested in the special subject discussed in an}^ particula
bulletin. This form of publication facilitates promptness of issue for
economic results, and most economic reports are therefore published
as bulletins. Their small size, however, precludes the use of large
maps or plates, and reports containing large illustrations are there-
fore issued in the series of Professional Papers.
3. Professional Papers of tin United States Geological Survey.—
This series, paper covered, but quarto in size, is intended to include
sueh papers as contain mapsor other illustrations requiring the use of
a large page. The publication of the series was commenced in 1002,
and the papers are distributed in the same manner as bulletins.
4. Monographs ofthi United States Geological Survey. — This series
consists of cloth-bound quarto volumes, and is designed to include
exhaustive treat iseson economic or other geologic subjects. Volumes
of this series are sold at cost of publication.
5. Geologic folios of the United Stoics Geological Survey. — Under
the plan adopted for the preparation of a geologic map of the United
States the entire area is divided into small quadrangles, bounded by
certain meridians and parallels, and these quadrangles, which num-
ber several thousand, are separately surveyed and mapped. The |
unit of survey is also the unit of publication, and the maps and
descriptions of each quadrangle are issued in the form of a folio.
When all the folios are completed thejT will constitute a C4eologic
Atlas of the United States.
A folio is designated by the name of the principal town or of a
prominent natural feature within the quadrangle. It contains topo-
graphic, geologic, economic, and structural maps of the quadrangle, and
occasionally other illustrations, together with a general description.
Under the law, copies of each folio are sent to certain public libra-
ries and educational institutions. The remainder are sold at 25 cents
HAYES.]
INTRODUCTION.
11
each, except such as contain an unusual amount of matter, which are
priced accordingly.
Circulars containing lists of these folios, showing the locations of
the quadrangular areas they describe, their prices, etc., are issued
from time to time, and may be obtained on application to the
Director of the United States Geological Survey. The tables on the
following pages show the folios issued to date, with the economic
products discussed in the text of each, the products of greatest
importance being printed in italics.
List of geologic folios showing mineral resources described.
No.
Name of folio.
State.
Area
in
sq. in.
Author.
Mineral products described
as occurring in area of
folio.
1
Mont ...
3,354
Iddings,J.P.;Weed,
W.H.
Gold, copper, clays, lime,
stone, coal.
. 2
Ringgold
Ga.-Tenn
980
Hayes,C.W
Coal, iron, manganese,
lime, clays, stone, road
metal.
:;
Placer ville
Cal
932
Lindgren, W.; Tur-
ner, H.W.
(! iild, copper, quicksilver,
chromite, stone.
4
Kingston
Tenn
969
Hayes,C.W
Coal, iron, lime, stone,
road metal, clay.
5
Sacramento
Cal
932
Lindgren, W
Gold, copper, chromite,
iron, coal, stone, lime,
clay.
6
Chattanooga
Tenn
975
Hayes, C. W
Coal, iron, lime, stone,
road metal, clay.
Pikes Peak-Crip-
ple Creek.
Colo
932
Cross, W
Gold.
8
Sewanee
Tenn
975
Hayes,C.W__.
Cool, iron, lime, stone,
road metal, clay.
9
Anthracite-
Crested Butte.
Colo
465
Eldridge,G.H._
Coal, silver, stone, lime,
clay.
11)
Harpers Ferry
Va.-W. Va.-
Md.
925
Keith,A
Iron, ocher, copper, stone,
road metal. lime, cement.
11
Jackson
Cal...
938
Turner, H.W
Gold, copper, chromite,
iron, manganese, ocher,
coal, stone, lime, clay.
r?
Estillville
Ya.-Ky-
Tenn.
957
Campbell, M.E ....
stone.
13
Preder icksbu r g
Md.-Va
93S
Darton,N.H
Qreensand m.arZ,stone, ful-
ler's earth, clays, sand,
gravel, underground
water.
14
Staunton
Va.-W. Va.:_
938
do
Iron, marble, lime, clay,
coal.
15
Lassen Peak
Cal
3,634
Diller,J.S ..
Gold , in f usor ial earth,
lime, stone, coal.
in
Tenn.-N.C...
969
Keith, A
Marble, slate, stone, gold,
lime, cement, (day, water
power.
17
Marysville
Cal
925
Lindgren, W.; Tur-
ner, H. W.
Gold, coal, gas, clay, lime,
stone, water supply.
is
Smartsville
do
925
do
Gold, copper, quicksilver,
iron, lime, clay, stone.
19
Stevenson ...
Ga.-Ala.-
Tenn.
980
Hayes, C. W
Coal, iron, lime, stone,
road metal, clay.
m
Cleveland . .
Tenn _ .
975
do
clay.
21
Pikeville
do..
969
969
do
do
22
McMinnville
do
Coal, iron, stone, clay.
23
Nomini
Md.-Va
938
Darton,N.H
earth, clay, stone, sand,
gravel, un dergro u nd
water.
12 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
List of geologic folios showing mineral resources described — Continued.
No.
Narne of folio.
State.
Area
in
sq.m.
Author.
Mineral products described
as occurring in area of
folio.
°i
Three Forks
Mont
3. S54
Peale,A.C.
Gold, silver, copper, iron,
coal, lime, clay, pumice,
mineral springs.
?5
Tenn
969
Keith,A
Coal, marble, lime, stone,
clay, iron, slate, water
power.
2(5
Pocahontas
Va.-W.Va...
950
Campbell, M.R
Coal, lime, stone, clay,
marble.
97
Morristown ..
Tenn
963
Keith, A ..
Marble, stone, lead, zinc,
lime, cement, clay, water
power.
28
Piedmont
Md.-W.Va...
925
Darton,N. H.; Taff,
J. A.
Coal, iron, lime, stone,
road metal, clay.
29
Nevada City spe-
cial.
Cal
35
Lindgren, W.
Gold.
30
Yellowstone Na-
tional Park.
Wyo
3,412
Hague, A.; Weed,
W. H.; Iddings,
J. P.
National Park; no mining
permitted.
31
Pyramid Peak
Franklin
( !al
932
Lindgren, W._
Gold.
32
Va.-W. V:i
032
I)art<m,N.H-.
Iron, coal, manganese,
lime, stone, road metal,
clay.
33
Briceville
Tenn
963
Keith.A
Coal, iron, lead, marble,
lime, stone, clay.
34
Bnokhannon
W.Va
932
Taff, J. A.; Brooks,
A.H
Coal, lime, stone, clay.
35
Gadsden
Ala
986
Hayes, C.W
Coal, iron, lime, stone.
36
Pueblo
Colo
938
Gilbert, G.K...
Stone, gypsum, clay, iron,
artesian water.
37
Downieville
Cal....
919
Tiiriirr,H.W--.
Gold, iron, ehromite, lime,
marble.
38
Butte special
Mont
*5
Emmons. S. F . ;
Tower, G. W.
( topper, silver, gold.
30
Truckee
Cal
925
Lindgren, W.
Gold, silver, coal, stone,
mineral springs.
40
Wartl mrg
Tenn . . .
963
Keith,A
Coal, oil, iron, lime, clay.
41
Sonera
Cal
94 1
Turner, H. W.; Ran-
some,F. L.
Gold, quicksilver, copper,
ehromite, lime, stone.
4*
Tex
1. 035
Hill,R.T.;Vaughan,
T.W.
Stone, gravel, under-
ground water.
43
BidwellBar
Cal
019
Turner,H.W
Gold, manganese, iron,
ehromite, stone.
44
Tazewell
Va.-W. Va .
051 )
Campbell, M.R
Coal, iron, barite.
45
Idaho
864
Lindgren. W
Gold, silver, coal, diato-
maceous earth, stone,
clay, springs, artesian
water.
4fi
Ky
944
Campbell, M.R
Coal, fluorite, phosphate,
clay, stone, road metal.
47
London __
do
050
do....
Coal, stone.
48
Tenmile district
special.
62
Emmons, S. F
Silver.
40
Roseburg
871
Diller, J S .
Gold, copper, quicksilver,
coal, clay, stone.
50
Holy oke
Mass.- Conn ..
8S5
Emerson, B. K
Granite, emery, ehromite,
quartz, trap, sandstone,
clay.
51
Big Trees
Cal
938
Turner, H. W.; Ran-
some, F. L.
Gold, silver.
52
Absaroka
Wyo ...
1,706
Hague, A
Silver.
53
Standingstone
Tenn.
063
Campbell, M.R
Coal, oil, lime, clay.
54
Tacoma
Wash
812
Willis, B.; Smith,
GO.
Coal, stone, clay.
55
Fort Benton
Mont .
3,234
Weed, W. H .
Gold, silver, lead, iron.
gypsum, coal, stone,
artesian water.
hayes. 1 INTRODUCTION. 13
List of geologic folios showing mineral resources described — Continued.
No.
Name of foli >.
State.
Area
in
sq. m.
Author.
Mineral products described
as occurring in area of
folio.
56
Little Belt Moun-
tains.
Mont ..
3,295
Weed,W. H
Coal, silver, lead, copper,
iron, sapphires, mineral
water.
57
Telluride
Colo
236
Purington, C. W
Gold, silver.
58
Elmoro
...do
950
Hills, R. C
water.
59
Bristol
Va.-Tenn ....
957
Campbell, M.R
<'<»il, iron, zinc, barite,
marble, clay.
61)
La Plata
Colo
287
Purington, C. W
(rolil, silver, coal.
61
Monterey
Va. W.Va.
938
Darton, N.H
Iron, stone, clay, road
metal.
62
Menominee spe-
cial.
Mich
125
Van Hise, C. R.;
Bayley, W. S.
Iron.
68 , Mother Lode dis-
trict.
Cal
428
Ransomo, F. L
Gold, silver, manganese,
quicksilver, stone.
64
Uvalde
Tex
1,040
Vaughan, T. W
Asphalt, gold, silver, iron,
coal, water supply.
65
Utah .
229
To wer,G.W.; Smith,
G. O.; Emmons,
S. F.
Gold, silver, lend, copper.
66 | Colfax
Cal
925
Lindgren, W
Gold, stone, clay, water
supply.
67
Danville
Ill.-Ind
228
Campbell, M. R
Coal, clay, gravel, under-
ground water.
6S
Walsenburg
Colo
944
Hills, R. C
Coal, stone, clay, artesian
water.
69
Huntington
W.Va-Ohio..
938
Campbell, M. R
Colli.
70
Washington
D.C.-Va.-Md
465
Darton, N. H.; Keith,
A.
Gold, iron, clay, stone,
road materials, green-
sand marls, underground
water.
71
Spanish Peaks
Colo
950
Hills, R. C
Coal, stone, gold, silver,
artesian water.
72
Charleston
W.Va
938
Campbell, M.R
Coal, salt, oil, gas, iron.
78
Coos Bay ...
Oreg
871
Diller. J. S
Coal, gold, stone.
74
Coalgate
Ind.T
980
Tuff, J. A
Coal, stone, clay.
75
Maynardville
Tenn
963
Keith, A .
zinc, lime, road mate-
rials, clay, water power.
76
Austin
Tex
1,030
Hill, R.T.; Vaughan,
T.W.
Oil, stone, lime, clay, ce-
ment, artesian water.
77
Raleigh _
W.Va
944
Campbell, M. R . .
Coal.
78
Rome
Ga.-Ala
986
Hayes, C.W
Bauxite, iron, slate, lime.
70
Atoka
Ind.T
986
Taff, J.A
Coal, stone, clay.
80
Norfolk
Va.-N.C
1,913
Darton, N.H
water.
81
Chicago
111. Ind
892
Alden,W.C
Stone, clay, molding sand,
water power, water
supply.
82
Masontown-
Uniontown.
Pa
458
Campbell, M. R
Coal, oil, clay, stone, glass
sand, iron.
m
New York City
N.Y.N.J....
906
Merrill, F. J. H.; Hol-
lick, A.; Darton,
N.H.
Trap, marble, granite,
road material, clay, iron,
water power, water
supply.
84
Ditney __
Ind .
938
Fuller, M. L.; Ash-
ley, G.H.
Coal, gas, clay, stone, iron.
85
Oelrichs
S. Dak.-Nebr
871
Darton, N.H
Stone, gypsum, lime, vol-
canic ash, underground
water.
86
Ellensburg
Wash
820
Smith, CO
Budding stone, road metal,
ground tenter, artesian
water.
87
Scotts Bluff
Nebr
892
Darton, N.H
Volcanic ash.
88
Camp Clarke
do
892
do
Volcanic ash.
14 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
6. Mineral Resources of the United States. — From 1883 to 1804,
inclusive, an octavo cloth-bound volume bearing the above title was
issued annually, with only two exceptions, the years L883-S4 and
1889-90 being included by pairs in single volumes. The first of this
scries was Mineral Resources of the United States, 1882; the last,
Mineral Resources of the United States, 189o. In 1894 this form of
publication was discontinued, in accordance with an act of Congress,
and the material was included in certain parts of the sixteenth, seven-
teenth, eighteenth, nineteenth, twentieth, and twenty-first annual
reports. The separate publication of the series on mineral resources
was resumed, however, in 1901, in accordance with an act of Con-
gress, and two volumes of the new series, Mineral Resources of the
United States for 1900 and for 1901, have been issued.
This publication contains a systematic statement of the production
and value of the mineral products of the United States, a summary
of new mineral resources developed, and occasionally short papers
on economic geology, when necessary in accounting for the new
developments.
INVESTIGATION OF METALLIFEROUS ORES.
By S. F. Emmons, Geologist in Charge.
INTRODUCTION.
In the years immediately following the organization of the United
States Geological Survey its geological work was classed under two
broad divisions, namely, general geology and mining geology. The
primary object of the latter work was, by careful scientific studies of
the most extensive mines and mining districts of the country, to
gather together such an array of accurately determined facts with
regard to the phenomena of ore deposition as would serve as a basis
for generalizations, or laws governing the formation of metalliferous
deposits. Incidentally it was expected that a demonstration of the
correct geological structure and relations of the deposits in each indi-
vidual district would prove of immediate practical value to those
engaged in mining in that district, and serve as a guide to them in
their explorations. This, however, was regarded as of secondary
importance compared to the first object, since general laws are useful
to mine owners the world over and are not confined in their applica-
tion to the mines of a certain district.
The commercial interest of mining industry was more directly sub-
served by the collection of statistics of the mineral resources of the
country, which was at first a branch of mining geology. As time has
gone on and, with increasing pecuniary resources, the field of work
of the Survey has widened, the above-mentioned classification of its
work has been somewhat changed in title, as well as in the scope of
the different divisions, but the main underlying principles have
remained practically the same.
The collection of mineral statistics is of direct commercial value to
mining industry, which was readily recognized by the general public,
and, direct and generous appropriations having been made for it, it
lias become a special division.
GENERAL GEOLOGY.
Whereas in the early days but little could be done toward preparing
•i geological map of the whole country, which is theoretically the prime
abject of a geological survey, because of the want of the indispensable
15
16 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
topographic basis for such a map, so great progress lias now been
made in the preparation of the topographic map that geological map-
ping is in an advanced stage, and what was formerly called "general
geology" is now mainly comprised under the term "areal geology."
Under the folio form, in which the separate sheets of the Geological
Atlas of the United States are published, there appears, together with
the topographic and areal maps of the given fraction of a degree which
it represents, a so-called economic map. The topographic map rep-
resents the physical relief, or shape of the surface; the arealt map
indicates by color conventions the area occupied on that surface by
the different varieties of rocks which constitute the surface, while on
the economic mail the different rock varieties arc so indicated that
emphasis is given to those which carry minerals of economic value.
Thus, the areal geologic work affords results of economic value, and
is, moreover, an indispensable basis upon which all economic studies
must be founded.
ECONOMIC GEOLOGY.
What was formerly called "mining geology11 is now designated
"economic geology," and in late years the scope of this work has so
greatly increased that it has been found advisable to have it con-
ducted under two general heads, with a geologist in charge of each,
namely, that of "metalliferous ore deposits," and that of "lionmetal-
liferous deposits," those of iron being included in the latter class
because of their close economic connection with coal deposits.
The investigation of deposits of metalliferous minerals as at present
conducted comprises several types of work varying with the condi-
tions under which it is carried on. These are: First, the investiga-
tion of important and extensive mining districts, such as Cripple-
creek, Leadville, etc., which may be called "special district sur-
veys." These are regions of unusually large concentrations of metal-
liferous deposits, where within a small area the underground workings
of a great many large mines have laid open to scientific observation
relatively large portions of the interior of the earth, and whose indi-
vidual outputs form a comparatively large fraction of the total
product of the country. Even in cases where such districts have
passed their prime from an industrial standpoint, their investigation
is of the utmost value, since it affords a scientific record of critical
phenomena which furnish material for the formulating of the general
laws spoken of above. Hence, this work must be done with the
highest degree of scientific accuracy and detail, and it generally occu-
pies the work of at least two field seasons — one by the topographic
corps in preparing the necessary maps, and one by the geologists in
making the areal and underground surveys.
To the general public, and especially to those who own mining
property in a region, it often seems that the publication of such work
is unduly delayed, since they are mainly anxious to learn the facts
emmons. J INVESTIGATION OF METALLIFEROUS ORES. 17
that directly aid in the development of their own property; but from
the point of view of those engaged in the work, and who are respon-
sible for a correct determination of the facts of nature, it is more
essential that these facts, upon which future generalizations must be
based, should be determined with the greatest possible accuracy than
that the public demand for prompt publication should be yielded to.
The second class of economic work may be called economic work
incidental to areal work. In regions that are under areal survey it
often happens that there are considerable mining developments, though
the important mines are not gathered together into one small area or
district, but occur at points so widely separated throughout the region
that it would be inadvisable to survey the whole area with the amount
of detail that is given to the work in special districts. In such cases,
after the areal surveys have been completed and published, economic
geologists are detailed to study the various mine developments of the
area with a view to the determination of facts of structure and gene-
sis of the ore deposits examined rather than of their immediate com-
mercial value. Such are the reports on the Telluride quadrangle by
Mr. Purington, and on the Silverton quadrangle by Mr. Ransome.
A third class of economic work is the reconnaissance examina-
tions, in which it is not intended to make a complete or exhaustive
examination of a mine or district, but such a characterization as may,
in a comparatively short time, bring out its most striking and evi-
dent features, both structural and genetic. Here again the primary
object, from the point of view of the Survey, is the gathering of facts
bearing upon the broader questions of structure and origin. As to
the practical bearing of such work in determining the probable value
in depth of individual deposits in a region which is still in the pros-
pect stage, mining men are apt to have somewhat exaggerated ideas.
While a geologist who has had wide field experience in studying
mining districts should be able to draw more valuable conclusions as
to the future prospects of a region as a whole than the prospector or
miner, as to an individual deposit, until it can be studied underground
over a considerable extent, both vertically and longitudinal^, he can
not, as a rule, obtain such scientific data as will enable him to give
an authoritative estimate of its probable value.
It has hitherto not been the policy of the Survey to publish this
reconnaissance work in all cases. It has been considered that, inas-
much as the very fact of publication of a report by the Survey gives
to its statement a measure of official indorsement by the Government,
and as courts of law have accorded to such publications an authority
as evidence in mining cases equal to that of a text-book on geology
or mining, incomplete material or opinions that are confessedly
liable to be changed or modified by more complete studies should not
be accorded the dignity of a Survey publication. Certain parts of
this work, foi instance the rapid examinations of mining districts by
Bull. 213—03 2
18 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
heads of divisions for the purpose of determining whether or not they
should be the subject of official examination in the immediate future,
are primarily not intended for publication. Again, visits are often
made to a number of different districts for the purpose of determining
certain isolated and special facts that bear upon some important
generalizations under consideration, and their immediate publication
might defeat the end for which they were made.
Facts of general interest, with regard either to special mines or to
mining districts, or generalizations from facts gathered in studies of
a great many mines or districts, but which are of a more or less tenta-
tive nature, have been published from time to time by members of
the Survey, under authorization of the Director, in some scientific
publication, such as the Transactions of the American Institute of
Mining Engineers, thus reaching directly and without delay the class
of persons most immediately interested in them, namely, the mining
engineers.
The practical working of this system was well illustrated during
the Washington meeting of the American Institute of Mining Engin-
eers in 1900. At this meeting papers were read by different members
of the Survey, as the result of their independent observations during,
a series of years, on the following subject s :
Some Principles Controlling Ore Deposition, by C. R. Van Hise.
Secondary Enrichment of Ore Deposits, by S. F. Emmons.
Enrichment of Gold and Silver Veins, by W. H. Weed.
Motasomatic Processes in Fissure Veins, by W. Lindgren.
These papers presented theoretical views upon the processes
involved m the formation of ore deposits which the respective authorsi
had been gradually arriving at during their Survey work. In most
cases they represented rather preliminary statements, made for the
purpose of stimulating discussion and investigation among mining
engineers, than final and completed results, such as would be expected;
from an official publication. Yet this prompt publication has been of
the utmost practical importance to mining industry, for the first thr
papers give a scientific means of answering a question of the most
vital interest to the investor in mines, to which, in spite of all that has
been written on it, only vague and contradictory answers had hitherto
been presented — the question, namely, whether veins (or ore deposits)
become richer or poorer with increasing depth. The answer was not
categorical, for such answers are seldom possible in so complicated a
science as geology, but it explained the manner of formation of the
very rich bonanzas which have made certain mines famous and why
they are succeeded by leaner ores in depth.
The stimulation of discussion and investigation, which was the gen-
eral purpose of such papers, has been so fully accomplished in thi&j
case that they have been followed by a series of important contribu-i
tions from the most eminent authorities on the study of ore deposits
emmons] INVESTIGATION OF METALLIFEROUS ORES. 19
in Europe, as well as in this country, and all have been gathered
together and published in a special volume by the Institute of
Mining Engineers. Such publications are not intended to be final.
Already, since the appearance of the above-mentioned volume, impor-
tant modifications of the views therein presented have been suggested,
and further important additions to our knowledge of the subject are
to be expected from the constantly increasing amount of accurate
work that is being done every year by the Survey.
A brief review will now be given of the published results of this
work, together with a statement of that which is in progress but has
not yet reached the stage of publication.
Economic Publications on Metalliferous Deposits.
During the year 1901 there was published in the Bulletin series, by
F. L. Ransome, a volume (Bulletin No. 182) on the Economic Geology
of the Silverton Quadrangle, which belongs to the second class of
economic publications mentioned above — that is, economic examina-
tions incidental to areal work. The Silverton quadrangle had already
been areally surveyed hy a party under the charge of Whitman Cross,
who has been engaged for a number of j^ears past in making a geo-
logical study of the whole region of the San Juan Mountains in south-
western Colorado. Under the system adopted by the Survey, as each
fraction of a degree — in this case one-sixteenth, or fifteen minutes — is
surveyed topographicaltyand areally, the results are published in folio
form, and when mining interests justify it an economic geologist is
detailed to work either with the areal party or following it and to make
a special study of the mines and ore deposits of the whole area. Such
a study had already been made by C. W. Purington of the mines of the
| Telluride quadrangle, and his results were published as a special
paper in the Eighteenth Annual Report.
The whole San Juan region is rich in ore deposits, occurring to an
unusual degree in well-defined fissures and also in more irregular
forms, called stocks or chimneys, which carry values in gold, silver,
i' copper, lead, and zinc. The Silverton quadrangle, which lies next
east of the Telluride, contains, like the latter, a large number of
important mines within its area. In many of these the richer ores or
bonanzas have been extracted and they are, for the time being, aban-
doned; others, such as the Camp Bird, Silver Lake, and Tom Boy, are
in active operation. The record obtained from the latter is naturally
the most valuable, but the former also afford data of importance.
IThis report contains not only a statement of the geological relations
of each important deposit in the area which must prove of practical
value to those engaged in mining there, but some very valuable gen-
tliijeralizations which Mr. Ransome was able to make from the lode
ilmi fissures and stocks or masses, also a statement of their contained min-
erals and their paragenesis and origin, as well as important contri-
butions to the new theory of enrichment of ores by descending waters.
20 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull, 213.
It is to be noted that under the new system of gratuitous distribu-
tion of such papers, recently ordered by Congress, the edition of this
report was exhausted within a few weeks of its appearance.
In Bulletin No. 178, W. II. Weed has given the result of a recon-
naissance examination of tin deposits in the Franklin Mountains, near
El Paso, Tex. The openings upon these deposits were too shallow to
afford very satisfactory data as to their probable value or continuity,
and the paper is mainly useful as proving the actual occurrence of
tin minerals at the locality named, since the existence of such miner-
als has often been announced without any satisfactory basis of fact.
Bulletin No. 18(5, on Pyrite and Marcasite, by H. N. Stokes, though
more strictly classed as a chemical paper, deserves mention here
because it represents the results of experimental observations on the
chemical processes which take place during the secondaiy enrichment
of ore deposits.
These investigations were undertaken b}7 the division of chemistry
and physics at the request of the geologists who had read papers upon
this subject at the Washington meeting of the American Institute of
Mining Engineers, and who felt that the theory needed confirmation
from the chemical side, since, while their field studies had shown that
certain conditions produced certain results, they necessariby could not
demonstrate the actual chemical processes by which those results had
been brought about.
Part II of the Twenty-Second Annual report, forming a volume of
nearly 900 pages, published in 1902, was devoted exclusively to reports?
upon ore deposits. These were:
(1) The Old Tungsten Mine at Trumbull, Conn., by W. H. Hobbs.
This is a geological description of an abandoned mine in a locality
which had long been classic for the fine mineral ogical specimens
obtained there. While not important from an economic point of view,
the paper is valuable as furnishing data with regard to the manner of
occurrence of the rare tungsten minerals — hiibnerite and scheelite.
(2) Lead and Zinc Deposits of the Ozark Region, by H. F. Bain and C. R. Van
Hise.
This report was made in response to a demand for a prompt pre-«
liminary statement concerning the lead and zinc ores of the Ozark
region. It is both areal and economic in character, and in some respect?
in the nature of a reconnaissance, since it was not possible under the
circumstances to make the study exhaustive, and work is still being car-
ried on in the region. Perhaps its most important result is the prac-
tical demonstration and confirmation of Professor Van Ilise's theory
with regard to the agency of surface waters in redistributing and!;
enriching the lead and zinc deposits of the Mississippi Valley region.'
and the indication of the practical deductions that may be drawr
therefrom to guide the miner in his search for ore.
BMMons.] INVESTIGATION OF METALLIFEROUS ORES. 21
(3) Ore Deposits of the Rico Mountains. Colorado, by F. L. Ransome.
This urea is also situated in the San Juan Mountains, and the eco-
nomic work followed an areal survey by Mr. Cross and his party, but
the conditions there differ from those in the Silverton quadrangle, in
that the ore deposits are concentrated within a limited area. It could
thus be properly made the object of a special survey, especially as the
peculiar nature of the ore deposits renders it unusually worthy of such
detailed study. Unfortunately, by the time the Survey was in condi-
tion to undertake this examination the principal mines had been prac-
tically worked out and a large proportion of their underground work-
ings had become inaccessible. This fact has given rise to some unfa-
vorable criticism of the methods of the Survey on the part of those
who consider that the most important result of its work is the imme-
diate aid afforded by it to the miner in the development of the mines
of the particular district under survey. In this case geological-con-
ditions are such that it would have been impossible to make a satis-
factory study of the ore deposits until the peculiarly complicated
geology of the whole quadrangle had been worked out. Further-
more, few mining districts present conditions so favorable for a definte
determination of some of the undertying principles controlling ore
deposition, conditions which the able mining engineers who had at
different periods had charge of the principal mines of the district had
of necessity been unable to completely understand, because the true
geological relations of the deposits were not yet known.
Mr. Ran some's report, in spite of the obstacles he had to contend
with in making the examination, gives a remarkably able and satis-
factory delineation of the conditions governing ore deposition along
bedding planes of limestone under impervious shales, in part replacing
a bed of gypsum, and associated with well-defined fissure systems and
different ial movements along bedding planes, and of the genetic con-
nection of its deposition with the intrusions of igneous rock in the
immediate vicinity. It constitutes a most valuable contribution of
well-determined facts bearing upon the general theoiy of ore deposits.
(4) Geology and Ore Deposits of the Elkhorn Mining District, Montana, by
W. H. Weed and Joseph Barrell.
This is mainly the study of one great mine; a mine, moreover, that
is practically worked out, and to which are applicable the same criti-
cisms that were made of the Rico report. Here, also, the study has
been extremely fruitful in presenting facts bearing upon the forma-
tion of a rather unusual type of ore body. The deposit is considered
Iby Mr. Weed to be in the nature of a saddle-reef deposit, formed in
crushed limestone under a shaly roof within arches of pitching anti-
clines, lie further considers the ore to have been deposited by hot
solutions rising from a cooling batholith of eruptive rock. There is
also evidence of secondary sulphide enrichment in the ore.
22 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
(5) Gold Belt of the Blue Mountains of Oregon, by W. Lindgren.
This report is the result of an elaborate reconnaissance examination
made by' the author in the summer of 1900 of an area somewhat over
50 by 100 miles in extent. It shows the ability and thoroughness that
characterize all of Mr. Lindgren's work, and will no doubt prove a
useful source of information to those engaged in mining in that
region. In actual scientific results such work is generally less fruit-
ful than would have been the same amount of time and labor devoted
to a smaller area containing well-developed mines.
(6) Ore Deposits of Monte Cristo, Washington, by J. E. Spurr.
This, the final report of the volume, is also in the nature of a recon-
naissance, since the region had not been previously mapped geolog-
ically and the available topography was on so small a scale as to afford
a very imperfect base for his geological observations. His time was
also limited; nevertheless, as the area was small (3^ by 4 miles), he
was able to make as fairly complete a study of the deposits and
map the geology in as much detail as the economic importance of
the region demands. His general conclusions are, first, that the ore
occurs mainly as replacements of certain igneous rocks and to a less
extent as the filling of open spaces; second, that they have been
deposited by descending waters, and hence that the best deposits will
be found relatively near the surface.
The other economic publications that have appeared during the
year 1902 are:
Bulletin No. 193. — Geological Relations and Distribution of Platinum and
Associated Metals, by J. F. Kemp.
This is an account of few known occurrences of platinum and
associated metals throughout the world, based upon the published
literature on the subject and supplemented, in the case of a few
occurrences in this country and Canada, by personal observations of
the writer. It contains also a discussion on the mineralogical asso-
ciation and probable origin of these metals.
Professional Paper No. 1. — Ketchikan Mining District of Alaska, with an Intro-
ductory Sketch of the Geology of Southeastern Alaska, by A. H. Brooks.
This is the first paper of a new series of quarto publications by the
United States Geological Survey, authorized by the law of Congress
of May, 1902, which confines the report of the Director to a single
volume, and directs that these papers, like the bulletins, shall be dis-
tributed gratuitously. It is a reconnaissance report on the present
mining development of this large district of southeastern Alaska,
which includes Prince of Wales Island and the adjoining mainland.
It is accompanied by a sketch of the geology of those parts of south-
eastern Alaska that have been visited by members of the Survey.
emmons] INVESTIGATION OF METALLIFEROUS ORES. 23
Economic Work on Metalliferous Deposits now in Progress.
In enumerating the different pieces of work which have not yet
readied the stage of completion, the order followed will be geo-
graphic, taking each State and Territory, in which actual work has
been done, in alphabetical order.
APPALACHIAN REGION.
Mining in the Appalachian region, except for iron and coal, has
been conducted mainly in widely separated localities, and there are
few concentrations of metallic deposits which form mining districts
comparable to those in the West; hence hitherto no studies of special
areas have been made. In the course of journeyings, however, obser-
vations have been made in different parts of the region, especially by
Mr. Weed, of the copper deposits, many of which have been reopened
since the rise in the price of this metal. On later pages he gives an
interesting summary of observations on various of these deposits,
notably in New Jersey, along the contacts of the trap bodies which
break through the Triassic rocks, in the interior of Maryland, and in
the southern part of Virginia and North Carolina. Such observations
will be continued from time to time as the conditions of Survey work
admit.
ARIZONA.
The copper production of Arizona has in recent years assumed an
economic importance rivaling that of the Lake Superior region and of
Butte, Mont., which up to a comparatively recent date had together
furnished more than two-thirds of the entire copper output of the
country. Its principal mines had in consequence been developed to
such an extent that their study promised to yield valuable data of vital
importance in the theory of ore formation, especially in the line of
secondary enrichment, a process which is particularly active in warm
and arid climates. Since the commencement of the decade, therefore,
considerable economic work has been done in this Territory, of whose
geology up to this time but little was known. The following areas
have been studied :
Bradshaw quadrangle. — This area was geologically surveyed during
the summer of 1901 and its economic resources studied, as far as their
development permitted, by T. A. Jaggar, jr., and Charles Palache,
instructors of geology at Harvard University. Under ordinary cir-
cumstances it would have been more logical to have commenced work
in this region on the Jerome quadrangle, which adjoins the Bradshaw
on the northeast, but work in this area would have necessarily been
incomplete because members of the Survey had been refused admis-
sion to the most important copper mine of the region, the United
Verde, by the owner of the mine, for reasons best known to himself.
24 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
The Bradshaw quadrangle contains important deposits of both cop-
per and gold in the same series of rocks in which those of the United
Verde occur, but developments on most of them had, unfortunately,
not been pushed to any great depth. The ores occur mainly as vein
deposits in old Algonkian schists associated with eruptives. One
important result of the work has been to detect a tendency in the ore
deposits to arrange themselves peripherally around the bosses of the
granite which outcrop in the area. The results of this work will be
published in f^lio form.
Glohe quadrangle. — This area was surveyed and its mines and ore
deposits studied in the autumn of 1901 by F. L. Ransome, assisted
during part of the time by J. D. Irving. It lies to the southeast of
the Bradshaw quadrangle and in a similar relation to the great Plateau
region of northeastern Arizona. It includes the important mines of
the Old Dominion and United Globe companies, together with many
other deposits, of both copper and silver, which are mostly replace-
ments of limestone associated with eruptive rocks. The report on
this district was completed during the summer of 1902 and will shortly
appear as Professional Paper No. L2.
Clifton-Mort nci quadrangle. — This area lies still farther southeast,
near the borders of New Mexico and also not far from the southwest-
ern edge of the great Plateau region. The three areas just mentioned
thus give important data as to the remarkable change of structure
from the horizontal attitude and comparatively undisturbed position
of the strata in the plateau to 1 heir ex1 remely broken and complicated
structure in the ranges of the Basin region. This area, which is of
even greater economic importance than either of the other two, was
studied by W. Lindgren, assisted by J. M. Boutwell. The field work
was commenced in the autumn of 1901 and continued well on into the
spring of 1902. The ore occurs mainly in limestone and associated
eruptive rocks. Mr. Lindgren is now engaged in the preparation of
his report, of which a brief summary is given on later pages.
Bisbee mining district. — This district was studied in 1892 hy F. L.
Ransome, assisted by J. Morgan Clements and A. B. Rock. The area
lies in the extreme southern part of the Territory, near the Mexican
boundary line. It has long been one of the most important copper
producers of the Territory, and, as in the last-named district, mining
has received a new impetus as the result of the recent impulse given
to copper mining in general through the increased demand for the
metal and its consequent rise in price. The ores occur in limestone
near eruptive rocks, but without the contact phenomena that charac-
terize the Clifton-Morenci deposits. They present remarkably clear
evidence of secondary enrichment by descending solutions. Mr. Ran-
some is at present engaged in preparing his report of the region, of
which a brief statement is given in this bulletin.
emmons] INVESTIGATION OF METALLIFEROUS ORES. 25
CALIFORNIA.
Shasta County. — The copper deposits around the head of the Sac-
ramento Valley in California have been assuming considerable
economic importance of late years, and as they present a somewhat
different type from those hitherto studied it has been judged wise
to make a special study of them. In preparation for this work
J. S. Diller was engaged during the summer of 1902 in making an
areal survey of the Redding quadrangle, which includes the most
important copper deposits. He has prepared a brief summary of
the results of his work, showing the general geological relations of
the deposits. Detailed topographic maps are now being prepared
of the smaller areas, in which the most important ore bodies occur,
preparatory to special economic surveys, which will be made as early
as practicable.
Neocene river systems of the Sierra Nevada. — A very large pro-
portion of the gold product of California is derived from gravels
deposited in the beds of rivers belonging to an ancient system of
drainage quite distinct and independent of the present river system
of the Sierra Nevada. These gravels are now buried beneath more
recent deposits and lava flows, and it is of great importance to miners
to be able to trace their probable position in still undeveloped areas.
In the course of his areal studies of the geology of the Sierra
Nevada Mr. Lindgren had accumulated a great many facts concern-
ing the location of these ancient river beds, parts of which had been
studied and mapped by the able engineers in charge of various large
hydraulic mining undertakings. During the summers of 1901 and
1902 Mr. Lindgren was able to devote part of the time allotted to
field work to a further examination of the Sierra Nevada region for
the special purpose of supplementing his previous observations so as
to give a comprehensive view of the whole river system and to
enable him to map the probable course of the earlier or Neocene
rivers. In this study, which is largely of a physiographic nature, he
has been efficiently aided by J. M. Boutwell. It is a work which
necessarily requires very careful platting and much deliberate con-
sideration. It will be prepared for publication as rapidly as the
press of work admits. Its condition is more fully described by Mr.
Lindgren on later pages.
COLORADO.
In Colorado no new economic surveys have been commenced during
the last three years. The writer, assisted by J. D. Irving, has con-
tinued the gathering of data for a supplemental report on the geolog}^
of the Lead vi lie district during such time as could be spared from his
regular duties of supervising the work in other fields. This work
will be mainly of scientific interest, as at this late day it can hardly
26 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [buiZ. 213.
be of much value in directing the explorations of those engaged in
mining. It will be chiefly valuable in furnishing a record of the
immense ore bodies that have been mined in the district during the
last twenty-five years, in showing the possibilities and limits of geo-
logical induction by contrasting their actual geological relations with
those predicated in the first report from such facts as were open to
observation. It will also afford further data for testing and modify-
ing the theories of ore formation propounded in that report. Circum-
stances are such that it is impossible to determine when this report
will be ready for publication.
IDAHO.
Mineral deposits of flu Bitterroot Range and Clearwater Moun-
tains.— In the summer of L899 Mr. Lindgren was engaged in making
a geological reconnaissance in those parts of Idaho and Montana lying
north of the Salmon River and extending from the Bitterroot Vallej7
westward to the lava plains of the Columbia. In the course of this
work he observed the scattered ore deposits that are developed in this
region, without, however, having time to make an exhaustive study
of them. The area is largely of granite, with some sedimentary quarts
zites, slates, and limestones, principally upon the borders. It is
notable thai in the central part of the granite area no important ore
deposits have yet been discovered. In the subsequent pages Mi'.
Lindgren gives an interesting summary of his observations and of the
structural relations of the various deposits observed.
MISSISSIPPI BASIN.
Studies have been made during the summer of 1002 in the Missis-
sippi Valley region, first, of the lead and zinc deposits of northern
Arkansas by G. I. Adams, and, second, of the lead and zinc deposits
of the Joplin district of Missouri and of the lead, zinc, and fluorspar
deposits of western Kentucky by W. S. Tangier Smith.
All these deposits belong to a general type geologically distinct from
those found in the mountains of the West, and are of special interest
on that account. Brief summaries of the results thus far obtained
will be found on later pages of this volume.
MONTANA.
Copper mines of Butte. — The first study of the extremely important
vein deposits in granite at Butte Mountain was made in the summer
of 1896, and the results were published in folio form the following
year. Not long after the completion of this report, as a consequence
of litigation which sprung up between the most important mining
companies of the region, a great deal of underground exploration was
done for the express purpose of ascertaining more accurately the geo-
bmmons.;] INVESTIGATION OF METALLIFEROUS ORES. 27
logical structure and relations of the vein. So many new facts were
thus learned, and so important was their bearing upon the theory of
vein formation, that it was judged wise to make a second and more
exhaustive study of the copper veins of the region. This has been
carried on by Mr. Weed and his assistant since the spring of 1901
almost continuously, though his work has been interrupted at times
by the necessity of completing other pieces of work. It was not
thought best to hurry this work to completion, for the reason that the
geological questions at issue had most important bearing in the liti-
gation that was going on, and it was desired to avoid, as far as possi-
ble, influencing the results of this litigation, lest there might be a feel-
ing that the opinions expressed, which must necessarily favor one
side more than the other, indicated a partiality to the favored side.
The work is now approaching completion, but, on account of its mag-
nitude, will not be published for some time. A brief summary of the
important results is given by Mr. Weed on later pages.
NEVADA.
A new mining district in southern Nevada has sprung into sudden
prominence bjT its shipment of rich gold ores to the smelters, espe-
cialty at Salt Lake. Nevada has hitherto been regarded as essen-
tially a silver-producing State, and mining there has languished since
the fall in the price of the white metal, hence the development of its gold
resources is of the greatest importance. A brief account by the writer
of the important gold mine at De Lamar, in southeastern Nevada, was
published in the Transactions of the American Institute of Mining
Engineers in 1901.
During the autumn of 1902, J. E. Spurr, after assisting Mr. Spencer
in the Grand Encampment work during October, was detailed to
examine this new (Tonopah) district of Nevada. lie had been taken
ill with typhoid fever just at the opening of the field season in July,
hence was obliged to commence his field work at so late a date that
he found it advisable during the winter to make microscopical and
chemical studies of his rock specimens at Washington. He will com-
plete his field work in the spring and early summer, and a reconnais-
sance will then be made of neighboring mining districts in the Silver
Peak quadrangle and elsewhere.
SOUTH DAKOTA.
Economic Resources of the Northern Black Hills, by J. D. Irving and S. F.
Emmons.
This work was designed to be published in conjunction with the
Sturgis-Spearfish folio, for which the field work was completed some
years since. Its publication has been delayed by the calling off of the
principal author, T. A. Jaggar, jr., to other duties, notably to the study
28 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
of the volcanic eruptions in the West Indies in 1902. As soon as Ms
introductory sketch of the geology of the region is received the manu-
script will be sent to the printer. It comprises an account of the
geological relations of the various ore deposits of the region, main]}7
gold bearing, and a partial sketch of the famous Ilomestake lode,
which is, unfortunately, incomplete because permission to enter the
mine was withdrawn by the management before the study had been
completed.
WYOMING.
During the summer of 1002 a geological party, under charge of
A. C. Spencer, was engaged in an areal survey of the Grand Encamp-
ment Mountains, of Wyoming, and in a study of the copper deposits
occurring there. The writer spent some time with this party in the
summer, and also examined the important deposits of the New Ram-
bler mine, in the Medicine Bow Range, on the opposite side of the
North Platte Valley. The mines in this region are as yet opened to
only moderate depth and the study of their deposits can not yet be
expected to yield important data bearing upon their genesis, but the
extremely detailed and careful stud}7 of the very complicated geological
structure of the region made by Mr. Spencer and his associates will
probably be of service in helping the development of its mines, and
will certainly be an important contribution to our knowledge of the
geology of the Rocky Mountain system. An abstract of this work is
given on later pages.
INVESTIGATION OF NONMETALLIFEROUS ECONOMIC
MINERALS.
By C. W. Hayes, Geologist in Charge.
The distinctly economic work being done by the Geological Survey
has shown a steady growth in extent and importance since its organi-
zation in 1879. As pointed out Iry Mr. Emmons, this was at first
directed largely to the investigation of the ore deposits of the precious
and semiprecious metals — gold, silver, mercury, copper, etc. With
the extension of areal mapping in preparing the Geologic Atlas of
the United States, investigation of the more widely distributed ores
of iron, manganese, and aluminum and the nonmetalliferous minerals,
as clay, stone, phosphate, coal, asphalt, oil, and gas, was taken
up. The natural grouping of these two classes of mineral products
and the importance of their investigation were recognized by organiz-
ing, within the Geologic Branch of the Survey, in 1900, the two sec-
tions of metalliferous ores and nonmetalliferous economic minerals.
Since that time sj^stematic investigations of the nonmetalliferous
minerals have been carried on, both in connection with areal geologic
mapping and independently of areal work. It is impossible to
describe in detail all of the work of this kind which has been done
by the Survey, but its character and extent may be indicated by a
brief mention of some of the more important investigations carried
on in recent years.
The nonmetamorphic iron ores have been studied chiefly in connec-
tion with areal mapping, and their distribution is shown in the
geologic folios for considerable areas in Virginia, West Virginia, Ten-
nessee, Georgia, and Alabama. The same is true of manganese, ocher,
stone, and slate.
All known occurrences of bauxite, the ore of aluminum, have been
visited and examined by Hayes.
The slate quarries of Vermont and eastern Pennsylvania have been
examined by Dale, and the more important slate localities in the
Southern States by Keith and Hayes.
Special studies of the marble belt of Vermont have been made by
Dale, and Keith has mapped the marble of East Tennessee.
The phosphate deposits of Florida have been investigated by
Eldridge, and those of Tennessee by Ha.yes, Ulrich, and Eckel.
Investigation of the coal fields of the United States has been of two
29
80 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
kinds, detailed areal mapping and general summaries. Under the
first class of work large areas have been covered in the Appalachian
coal field, and the results have been published in numerous folios. The
work in Pennsylvania and West Virginia has been carried on by
Campbell and his assistants; in Tennessee by Campbell, Keith, and
Hayes, and in Georgia and Alabama by Hayes. Work has also been
done in southern Indiana by Campbell, Fuller, and Ashley; in the
southwestern field in Indian Territory by Taff and Adams; in the
Rocky Mountain fields in Montana and Colorado by Weed, and in
the Pacific fields by Diller, AVillis, and George Otis Smith.
The principal work of the second class has been the preparation of
a series of papers, 12 in number, summarizing existing knowledge
relating to coal fields of the United States. These are more fully
described on later pages.
The investigation of oil and gas fields has only recently been taken
up. During the last year certain portions of the Appalachian field
have been studied by Campbell, Griswold, and Fuller. The work of
Griswold in the Cadiz field is especially noteworthy, since it is the
most successful attempt thus far made to work out the structure of
the oil-bearing sands by instrumental means and with a high degree
of accuracy. A thorough reconnaissance of the oil fields of Califor-
nia has been made by Eldridge, and of the Texas-Louisiana fields by
Hayes and Kennedy. The Boulder oil field of Colorado has been
studied by Fenneman.
All known asphalt deposits of the United States have been exam-
ined and reported upon by Eldridge, and those of Arkansas and
Indian Territory have been examined in detail by Hayes, Adams, and
Taff.
A general reconnaissance of the clay resources of the United States
east of the Mississippi River has been made by Ries, and his report
is now in press. Detailed studies of particular deposits have been
made by Vaughan in Georgia and Florida, and by various geologists
in connection with their areal mapping.
Important economic work has also been done under the section of pre-
Cambrian geology, especially upon the iron ores of the Lake Superior
region. All of the iron-bearing districts have been studied by Van
Hise and his assistants, Clements, Bay ley, and Leith, and reports are
either published or in press. Also under the supervision of Van Hise
the lead and zinc mines of the Mississippi Valley have been examined
in the Ozark region by Bain, Adams, and Tangier Smith, and in
western Kentucky by Ulrich and Tangier Smith.
GOLD AND SILVER.
In addition to the papers here included, which represent the results
of recent work by the Survey in important precious metal mining
districts, other reports bearing incidentally on the subject of gold and
silver will be found Under the head of "Copper," on pages 105 to 186.
PROGRESS REPORT ON THE PARK CITY MINING DISTRICT,
UTAH."
By J. M. Boutwell.
INTRODUCTION.
Field work. — During the field season of 1901 two detailed topo-
graphic maps of portions of the Park City district were prepared by
this Survey under the direction of E. M. Douglas, geographer in
charge, by Pearson Chapman and J. F. McBeth. The general map,
showing an area of approximately 32^ square miles on the scale of 3
inches to 1 mile, embraces the general area in Park City through
which mining operations have been conducted; and the other, on a
scale of 1 inch to 1,000 feet, or 5.2 inches to a mile, includes only that
portion of this area which lies in immediate proximity to the largest
producing mines.
Late in the field season of 1902 a detailed study of the areal and
economic geology of the Park City mining district was undertaken by
J. D. Irving and J. M. Boutwell, under the supervision of S. F.
Emmons, geologist in charge of metalliferous deposits, and was con-
tinued into December of that year. This was the first systematic
geological work in this region since Emmons mapped the broad fea-
tures of the range in 1869, while engaged in the " Geological Explora-
tions of the Fortieth Parallel," under the late Clarence King, and was
the first detailed geological examination of an extended area in the
Wasatch Range. Before detailed work in the area under survey
could be advantageously undertaken a general knowledge of the
geological history of this portion of the range and the establish-
ment of the geological succession were required. Accordingly, the
general geology of the region surrounding the special field of work,
including the main divide of the Wasatch Range to the west, its
"This sketch is merely a preliminary statement indicative of progress. A complete report
will be published after a detailed survey has been completed.
31
32 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213
eastern slope, and the adjacent portion of the Uintas to the east, was
studied en reconnaissance, and detailed stratigraphical sections in the
nearest undisturbed areas were examined and measured. The area
included in the general map of the Park City district was then trav-
ersed, a considerable part of this area and also of that shown on t lie
map of the region immediately about the mines was mapped in final
form, and a reconnaissance study of the chief mines was conducted.
Dining the few weeks which have elapsed since the close of these
field studies the nature of the writer's work has not enabled him to
obtain any significant results from mineral and rock determinations
and the correlation of geological data from this district beyond those
which were gained in the field. It should be understood, therefore,
that while broad geological conclusions have been reached, and in
some cases detailed results secured, final conclusions regarding areal
and economic problems have not been attained. In view of this fact
it is a matter of some doubt as to how much value may lie in these
general statements, based upon incomplete and unstudied data. The
following brief statement is presented, however, in the hope that it
may be of some service in the extensive development which is now in
active progress. Only t he general geological facts thus far determined,
and such broad economic features as seem least likely to be altered
by detailed underground studies, are given, and the statements are
to be regarded as field opinions and tentative conclusions, subject to
partial or complete modification after further field work.
After briefly touching on the geography, history, and production
of the district these general preliminary results will be given under
the following headings: Under "Areal geology" will be discussed the
stratigraphy, igneous rocks, and structure; and under "Economic
geology " will be treated the character and occurrence of ore and
present mining activity.
Geography. — Park City is pleasantly situated on the eastern slope
of the Wasatch Range, in the north-central part of Utah. It lies
about 25 miles southeast of and 3,000 feet above Salt Lake City,
at an elevation of 7,200 feet above sea level. In its location on the
southern edge of a high-lying mountain prairie, at the junction of
three great canyons which there descend to the prairie from the main
range, this thriving mining town (population, census 1900, 3,759) has
a position of rare commercial value. A branch line of the Rio Grande
Western unites it by way of Parleys Park with Salt Lake City (35
miles), and a branch line of the Union Pacific (28 miles) extends from
the main line at Echo. It thus forms a most convenient outlet point
for the producing mines of the district, which are all located on the
slopes of the canyons which rise from this point southward.
The Wasatch Range in the portion south of Salt Lake City is a
lofty mountain unit, trending generally north and south between the
Great Basin on the west and mountainous plateau regions on the east
boutwell] PARK CITY MINING DISTRICT, UTAH. 33
Its western slope presents a wall-like front of striking steepness,
which is deeply incised at regular intervals by narrow rock-walled
canyons. The portions intervening between these canyons show a
marked type of dissection, which is characterized by ravines that rise
from the level of the desert with steep sides and bottoms, and fork
repeatedly and symmetrically upstream. The eastern slope, in
marked contrast, is a gradual descent to upland ranges, plateaus, and
high-lying meadows, which extend in a north-south belt along the
eastern base of the range. This unsymmetrical range may thus be
compared to a mammoth step, about 3,000 feet in height, from the Great
Basin on the west up to the highlands which extend from its upper
portion eastward. That part of the upland which adjoins this range
is drained by streams which flow westward through the great canyons
into the basin.
The Park City district embraces a tract which lies between the pre-
cipitous walls of barren rock, inaccessible cliffs, and ledges that mark
the crest of the main range to the west, and the grass}^, verdant,
mountain meadows of Heber, Kamas, and Parleys, along its eastern
foothills. This intermediate belt lies upon the northern portion of
a prominent spur which stretches from Clayton Peak in the main range
toward the east. This spur forms the head ward portion of East Can-
yon, divides the Weber from the Provo, and is the connecting link
between the Wasatch Range and the Uinta uplift. It comprises three
topographical divisions — a steep slope southward, which overlooks an
extensive, relatively level tract to the south, Bonanza Flat; a gradual
descent northward, which is deeply cut by four narrow, steep-sided
gulches, Thaynes, Woodside, Empire, and Ontario; and a long, steep,
deeply incised slope eastward, which unites the Park City upland with
the prairie belt.
The climate is remarkably bracing, with short, cool summers, short
autumns, and long rigorous winters marked by heavy snowfalls and
low temperature. Being on the protected sunny side of the range,
however, it escapes much of the harshness of such conditions which
neighboring canyons suffer. Water, although hardly abundant, is
not scarce. Springs and currents cut by underground workings sup-
ply a constant flow of Avater the year round. Natural rock basins at
the foot of the pinnacle of Clayton Peak are utilized as reservoirs,
and a supply of water which is sufficient for domestic purposes is
obtained from the Alliance tunnel. The outflow from the Ontario
drain tunnel, which is generally believed to include the drainage
from a large portion of the great mines, furnishes the power for the
Park City electric-light plant. Although the slopes originally sup-
ported a growth of pine timber 3 to 5 feet in diameter, this was early
utilized for underground timber. Fuel is supplied from extensive
veins of good coal at Coalville, 28 miles to the north, and from the
forest growth on the distant portions of this and the Uinta ranges.
Bull. 213—03 3
34 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
History. — The earliest mining in this part of Utah was in the Miller
mine, at the head of American Fork Canyon; in the Emma, Flagstaff,
and other mines near Alta, at the head of Little Cottonwood Canyon ;
and in the adjoining districts at the head of Big Cottonwood Canyon
and Snake Creek. In those days the Miller and Emma were famous
mines and the Park City region received slight attention. Although
desultory mining had been carried on in this area on various properties,
such as the Pioneer, Clara Davis, Badger, White Pine, McHenry, etc.,
for a few years previous, actual mining may be said to have begun
with the discovery of the Ontario mine; and the early history of this
mine is generally considered to constitute the early history of the
camp.
The Ontario mine is generally believed to have been discovered by
Rector Steen and his associates " about June 15, 1872." He describes
the discoveiy as follows:
When we discovered this mine we found a little knob sticking out of the
ground about 2 inches. We scraped the dirt off the lead about 50 feet along the
lead. It was about 18 inches wide, and when we got down 8 feet it narrowed in
to 8 inches. We had the rock assayed and it went from 100 to 400 to the ton.«
On August 21 of the same year the discoverers sold the property to
Messrs. Hearst and Stanley for $30,000. During the succeeding years
development work was energetically conducted through tunnels from
the main ravine. In April, 1878, the first shaft was started. Since
then two more shafts have been sunk (the deepest recently attained a
depth of 2,000 feet), and extensive underground development work
has been in constant progress. As a result of these operations since
its final incorporation in 1883, this property has produced silver which
has been sold for $33,255,950, and since 1901 dividends amounting to
$13,752,500 are stated to have been paid.
The success which attended these operations stimulated exploring
and locating throughout the district, and the ground through which
the Ontario lode was supposed to extend from the northeast to the
southwest was quickly taken up and developed. This resulted in the
extension of successful mining operations to the west, in the ground
now owned and operated by the Daly, Daty-West, and Daly- Judge
mining companies. In 1880, eight years after the discovery of the
Ontario, there were 1,270 mining locations registered in this (the
Uinta) mining district, although only 500 were active. Development
progressed steadily until 1893, when the decline in the price of silver
seriously crippled the camp. Improvement in the lead market, the
high grade of ores, and important improvements in the treatment of
ores made it possible to resume mining activity at an early date,
"Mr. Steen, who is still enjoying good health after a succession of arduous hardships encoun-
tered in prospecting in California, Montana, Wyoming, and Arizona, previous to his discovery
of the Ontario, has kindly supplied valuable data concerning the early history of this camp,
which will be included in a detailed historical sketch in the complete report.
BOUTWELL.]
PARK CITY MINING DISTRICT, UTAH.
85
and this activity has continued and increased consistently to the
present time. Since the middle nineties, when valuable ore bodies
were discovered, outside of the previously productive area, in the
Mayflower, Woodside, and Silver King properties, exploration has
been carried on over a large tract, and the productive area has been
widely extended. At present mining is extensively conducted in the
Silver King, Daly- West, Ontario, and Daly- Judge properties; impor-
tant work is being carried on in the Kearns-Keith, Keystone, Cali-
fornia, Comstock, and other properties on the west; in the Little
Bell, J. I. C, and Thompson groups on the south; and in the Nail-
driver, Wabash, New York, etc., on the southeast. Work is con-
templated for the coming season by owners of various properties on
the eastern and northeastern borders of the district.
Production. — The product of the Park City mines consists chiefly of
silver, and, in minor quantities, of lead, copper, and gold. The pro-
portionate value of these four metals (silver, lead, copper, and gold)
in the present output may be roughly stated as 9.1 to 2.6 to 0.39 to
0.28. The quantity and value of the output have increased strongly
in recent years, and may be reasonably expected not only to have
increased in 1902 but to continue that increase in the immediate
future. The following table, taken from the report by B. H. Tatam
in the Annual Report of the Director of the Mint for 1901, shows the
kind, quantity, and value of ore produced in Salt Lake County, Utah
(practically entirely from Park City), during the years 1900 and 1901.
Kind, quantity, and value of ore produced in Salt Lake County, Utah, during
1900 and 1901.
Metal.
1900.
1901.
Increase.
Quantity.
Value.
Quantity.
Value.
Gold fine ounces. .
Silver (coining value),
..fine ounces..
Copper fine pounds. .
Lead do
Total.
9,093.375
3,931,205
703,369
46,982,647
$187,976.74
5,082,770.10
113,875.44
2,053,141.67
13,731.376
7,060,623.56
2,477,080
60,232,236
$283,852.73
9,128,887.03
399,230.98
2,610,465.11
$95,875.99
4,046,116.93
285,355.54
557,323.44
7,437,763.95
12,422,435.85
4,984,671.90
AREAL GEOLOGY.
General geology of the region. — In its geological structure the Wasatch Range
presents a type of extreme complication, contrasting strongly with the simplicity
and regularity of its nearest neighbor, the Uinta Range. The simplest expres-
sion of this structure would be that of a sharp north and south anticlinal fold
over preexisting ridges of granite and unconformable Archean beds, whose axis
has been so bent and contorted by longitudinal compression that it at times
assumes a direction approximately east and west. In connection with the folding
has been developed a widely-spread system of faulting and dislocation, in a direc-
tion generally parallel with the main line of elevation, which has cut off and
thrown down the western members of the longitudinal folds and the western ends
36 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
of the transverse folds, which are now buried beneath the valley plains, while the
detailed structure has been still further complicated by a system of transverse
faulting. * * *a
That portion of the range which is included between Utah Lake and Emigra-
tion Canyon forms a geological whole, consisting of a series of sedimentary for-
mations, flexed around a body of * * * granite. * * * Horizons from the
Cambrian up to the Middle Coal Measures are at different points in contact with
the granite body. * * * Of the immense arch which once covered this body
the western half has been faulted down, while the top of the arch, with its thick-
ness of 30.000 feet of rock masses, has been broken up and worn away by
atmospheric agencies. b
The composite crystalline mass comprising the granite of Lone
Peak and Little Cottonwood Canyon, the granodiorite at the heads of
Big and Little Cottonwood canyons, American Fork, and Snake Creek
(Provo), and the diorite at the heads of Big Cottonwood, East Can-
yon, and Snake Creek, with its extensions northeast through the
Park City district, in the form of dikes, is the dominant factor in the
greater geological structure of the middle Wasatch. The ages and
the relationships of these great intrusive masses have not yet been
completely established. In a broad structural sense the bodies may
be regarded as forming an immense composite laccolith. In this light
the striking obliteration of the normal anticlinal structure of the
Wasatch, and the marked quaquaversal dip in this immediate section,
become significant. The Algonkian on the west, the Cambrian to
Mesozoic on the north, the Carboniferous on the east, and the Cam-
brian to Carboniferous on the south, each dipping away from this
intrusive center, are seen to be the flanks of a great laccolithic dome.
This main structural feature, supported by the evidence afforded by
the intrusive character of the contact between the crystallines and
the elastics, by the marmorization and deformation of the adjacent
country rock, and by the occurrence of an unusually complete series
of typical contact-metamorphic minerals, is conclusive as to the part
this intrusive mass has played in the history of the region.
Stratigraphy of the district. — The stratigraphical series in the imme-
diate vicinity of Park City has been so modified by faulting, intru-
sion, and metamorphism that no reliable extended section could there
be found. One on the north side of Big Cottonwood Canyon, between
1 and 2 miles west of Park City, was studied in detail. As several
requests have been received for information regarding this section,
for the purpose of establishing the relative position of the ore-bearing
members in this mining district, a general summary of that section
is given. The sedimentary series includes three chief rock types —
quartzite, limestone with calcareous sandstone, and shale. In gen-
eral, the succession (from the older to the younger), the thickness,
« Emmons, S. F., U. S. Geo!. Expl. 40tb Par., Vol. II, p. 341.
&Ibid., pp. 353-355.
boutwell] PARK CITY MINING DISTRICT, UTAH. 37
and the probable age of the larger divisions are as follows: (1) lime-
stones of improved thickness, probably of Lower Carboniferous age;
(2) 1,500 feet of massive normal quartzite, unfossiliferous, probably
of Upper Carboniferous age; (3) 590 feet of calcareous beds, mainly
blue limestone, with some shale, of Carboniferous age; (4) 1,100 feet
of red shale and sandstone, probably of Mesozoic age; (5). 450 feet of
calcareous sandstone, interbedded limestone, shale, etc., Mesozoic;
(6) 140 feet of red shale, Mesozoic; (7) 630 feet of limestone, calca-
reous sandstone, and gray shale, Mesozoic; and (8) an unproved thick-
ness of red shale, Mesozoic (?).
The correlation of members of this series throws light upon their
relation to the ore-bearing rocks in neighboring mining regions. The
lowest limestones here may be tentatively correlated with those on the
divide north of Alta and with those which underlie the main ore-
bearing series at Bingham. Accordingly the main quartzite of Park
City may be tentatively correlated with the great quartzite series in
lower Weber Canyon in the vicinity of the railroad tunnels and with
the main quartzite at Bingham. Valuable data upon the geological
history of this region have been secured in the course of this strati-
graphical study. They will not be considered in the present abstract,
however, since the character of the country rock is of more direct
economic interest.
Igneous rocks. — Within this area igneous rocks of three types have
been found — a fine, even-grained dioritic type, a coarser porphyritic
type, and a poorly defined type which ranges from andesitic to basaltic
facies. The first two are intrusive in origin; the last, so far as it may
be judged from the present incomplete data, is extrusive or volcanic
in origin.
The origin of these rocks bears directly upon two in'actical matters
of deep importance to mining men — the extent and the origin of ore.
The extrusive or volcanic rocks (those which flowed out upon the
surface) are often found to be in the form of a blanket overlying the
country rock, and as such would not be expected to lead to ore forma-
tion nor to truncate in depth previously formed ore bodies. The
intrusive masses, however, having reached their present positions and
forms through injection in the state of a semiliquid pasty magma into
the sedimentary country rock, may reasonably be expected both to
have generated ore and to have truncated any previously existing ore
bodies which lay in their paths. That is to say, the intrusions of
diorite and diorite-porphyry do not underlie the sediments as a foun-
dation of older rocks, nor do thej^, like the extrusives, overlie the
sediments, but they break irregularly across the sediments from bed
to bed. When the molten magma came in contact with certain lime-
stones, it led to the formation of various secondary minerals, and in
those limestones which possessed suitable comrjosition it may have
induced the formation of ore.
38 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
Geological structure. — The sediments in the immediate vicinity of
the Park City area have a general northeast-southwest strike, and an
average dip of about 40° NW. In general, then, the highest, or young-
est beds occur in the northwest portion of the area, and the lowest or
oldest in the southern and southeastern portions. But they have suf-
fered strong deformation from two potent factors — Assuring with fault-
ing, and intrusion. Although intense fracturing occurred in both
north east- south west and northwest-southeast directions, the prevailing
trend of the principal fissures thus far studied is northeast- southwest.
The more common dip is steeply to the northwest, although some impor-
tant fissures of this series dip to the southeast. The intrusions occur
as regular laccolithic masses and as dikes. They extend northeast-
ward through the district, in a direction accordant with the zone of
weakness indicated by t lie fissures, from the great dioritic body of
Clayton Peak on the sout Invest to extensive extrusive masses on
the northeast. They sometimes disturb the prevailing dip of the
sediments and cause local doming, as on the divides to the southeast
and southwest of "Bald Mountain. Distinct southerly dips noted in
the latter locality emphasize the general laccolithic character of this
great northeast-soul invest, belt of intrusives.
ECONOMIC GEOLOGY.
General. — During the season of 1902 work was directed chiefly
toward examining the areal geology with a view to establishing a firm
foundation for later underground studies. Such information as was
secured about economic questions was necessarily of a preliminary
nature, so that only a few general characteristics will be given in this
statement of progress.
The Park City mining district stands very prominently among the
great mining districts of this country as the home of large bodies of
silver-lead ore carrying minor values of gold and copper. In 1901
Park City mines supplied, roughly, seven -elevenths of the total out-
put of silver from Utah and were the main factor in maintaining Utah's
rank as third among the silver-producing States.
Although relatively young, Park City is, in several ways, a great
camp. Mining is conducted on an extensive scale, according to
advanced methods, by able, experienced men. Ten shafts have
reached a depth of at least 1,000 feet, 6 are down 1,300 feet or more,
and 1 — that one, too, whose collar is lowest — has attained a depth of
2,000 feet. There are four long drain or work tunnels, the longest of
which extends out to the eastern slope, a distance of about 3 miles.
Three large, highly efficient concentrating mills have been erected at
individual properties for private work, and an enlarged sampler and
a recently remodeled zinc plant are located below the town for custom
work. An aerial tramway and a broad-gage railroad transport ores
boutwei,!,.] PARK CITY MINING DISTRICT, UTAH. 39
from the mines to the Rio Grande Western system for shipment to the
custom smelters in the Jordan Valley. These perfected plants and
extensive operations, by which mining expenses are reduced to a
minimum, are rendered possible by a wise consolidation of interests.
Thus large tracts are owned by single companies; the bulk of the
output for the last year was supplied from two properties, and the
reputation of the camp rests upon the record of five great properties.
Character of the ores. — The values of the Park City ores (named in
the order of their importance) lie in their silver, lead, copper, and
gold contents. Silver has been reported in the form of several silver
minerals, and doubtless lies principally in the galena and gray copper.
Lead is present chiefly in the form of massive cleavable galena in the
sulphide zone, and of crystalline cerussite, amorphous auglesite, and
complex oxides in the zone of surface alteration. Copper occurs for
the most part as gray copper (tetrahedrite) in the sulphide zone, and
in the form of the blue and green carbonates (azurite and malachite)
in the oxidized zone. The mineralogical character of the gold is not
known, though it may occur as an impurity in pyrite. Zinc is a
common associate in the fissure ores.
Superficial alteration has descended to great depths. Some ore
bodies in limestone have been almost entirely altered to oxides, car-
bonates, and sulphates to the depth of 900 feet below the present
surface, and the effects of oxidation may be observed upon the walls
of sulphide ore bodies and adjacent to fissures cutting them, even to
a depth of 1,300 feet. At present both the oxidized and the sulphide
ores are mined.
These include large amounts of both first-class smelting ore and
milling ore. Several bodies of very high-grade ore — bonanzas — have
been discovered. Ore from the upper levels, 100 to 400, on a great
lode of this district is reported to have run from $40 to $700 a ton,
with an average of $130, and in 188G "the best" Ontario "ore was
sold to smelters and averaged $94.82 per ton. Ores of lower grade
were milled averaging 54.32 ounces of silver."" The average value
of crude ore shipped during the year 1902 from one of the principal
properties of the camp was between $28 and $29 per ton.
Occurrence of ores. — The Park City ores do not appear to be gener-
ally distributed throughout the region in small amounts, but rather
to be localized in certain well-defined occurrences in large bodies of
pay grade. Three main types of occurrences have been recognized —
fissure ores, replacement ores, and contact ores. In the first the ore
carries either silver and lead, with or without zinc and gray copper,
or gold with some silver, and occurs between well-defined fissure
walls. In the second the ore holds silver and lead values chiefly and
takes the form of elongated lenses within limestone, roughly parallel
aAlmy, T. J., History of Ontario mine, Park City, Utah: Trans. Am. Inst. Min. Eng., vol. 16,
p. 37.
40 CONTRIBUTIONS TO ECONOMIC GEOLOOY, 1902. [bull. 213.
to the bedding. In the last the ore contains copper and gold, with
or without lead and silver, and forms in irregular masses, pockets,
lenses, and pencils in metamorphic limestones adjacent to intrusive
bodies. Gold values appear to run highest in certain fractures in
quartzite; zinc is reported to increase in the southwestern extension
of the great fissure zone of the camp, and copper is said to reach its
maximum in amount and value in the deeper portions of certain
pseudo-fissures in quartzites.
Present activity. — During the last year mining in this district has
been remarkably active. Forty-eight new locations, the largest num-
ber reported from any mining district in the State, have been recorded.
A number of heavily capitalized companies have been incorporated,
several deep shafts begun, and exploration work vigorously pros-
ecuted in various quarters. Precisely what the results will be no
one can foresee. Several pieces of virgin ground which are now
being explored have been selected with considerable judgment. In
a mining boom, however, some properties are inevitably overvalued,
and it can not be expected that all will prove equally profitable. Nat-
urally among the conservative men who have developed the present
district by legitimate mining there is a strong feeling of opposition to
anything in the nature of booming, which might be prejudicial to the
permanent prosperity of the camp. In brief, it may be said that if
no serious decline in the price of silver occurs the prospects for a con-
tinued increase in the earnings of the camp through legitimate mining
in the immediate future are most favorable.
PLACER GOLD MINING IN ALASKA IN 1902.
By Alfred H. Brooks.
GENERAL STATEMENT.
The great impetus given to prospecting for gold in Alaska, incident
to the discovery of the rich Klondike fields, has resulted in the find-
ing of a number of new and in the further development of several old
placer districts. The gold output has shown a correspondent increase,
rising from two and one-half millions in 1897 to about eight millions
in 1902. While the development of quartz mining in the Pacific
coast province of Alaska has steadily progressed during this time,
more especially in the last two years, this development has not as yet
affected the increase of output to any appreciable extent, for the pro-
duction of the lode mines has remained practically the same. In
southeastern Alaska plans have been formulated for extensive min-
|| ing developments, and in many localities these plans are nearing com-
pletion; but as yet, outside of the older mines, such as the Tread well,
i there are few which are actually producing. The increase of
$5,500,000 during the last five years has, therefore, been chiefly from
the placer mines. It is to be expected, however, that the quartz
| mines of southern Alaska, which are being opened up, will within
the next two years add material^ to the mineral production of the
Territory.
Of the $6,000,000 or morea produced from the placer mines of
Alaska in 1902, about $5,500,000 has come from the Seward Peninsula
gold fields. The new diggings in the Copper River region have prob-
ably produced $225,000, and the Cook Inlet region and Porcupine dis-
trict have probably produced $100,000, while the remainder is from
the Yukon Basin, chiefly from the new diggings on Glenn Creek.
DISTRIBUTION AND SOURCE OF PLACER GOLD.
Placer gold has a wide distribution in Alaska. It has been found
near the southern boundary of the Territory, and at various localities
northward as far as the sixty-eighth parallel of latitude and west-
ward as far as Bering Strait. Broadly speaking, the producing placer
a The exact production is not yet known, but is not less than five aud one-half and possibly
may be six and a half millions.
41
42 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
mines of Alaska which have thus far been opened up fall within a
zone having a maximum width of probably 200 to 300 miles, stretch-
ing northwest from the southern Pacific coast, crossing the Arctic
Circle, and bending westward to the shores of Bering Strait. It is
not intended to imply that this zone in its entirety is a gold producer;
such is far from being the case. This broad belt is simpty drawn
attention to as having, up to the present time, been the locus of the
placers of commercial importance. The factors which have deter-
mined the formation of workable placers are frequently so local in
their effect that the distribution of the placers is very irregular.
The field studies lead to the conclusion that the source of the gold
lies, for the most part, in small quartz veins and stringers which are
disseminated in metamorphic rocks. Gold also occurs in these rocks
in the mineralized zone, where there is little if any gangue mineral
present. Iron pyrite is the commonest mineral found in association
with the gold in the parent rock. The few observations made indi-
cate that the gold occurs both free and combined with pyrite. Quartz
is a common gangue mineral, associated with some calcite. Galena
is frequently associated with the gold-bearing quartz veins, and chal-
copyrite and arsenopyrite have also been found. This list of minerals
will undoubtedly be much extended when closer studies have been
made.
The studies of the placer fields of Alaska lead to the conclusion that
the gold in nearly every case lias not traveled far, and can usually be
traced to a local source. In the gulch and creek placers it can usu-
ally be traced to a source within basins which they drain. The excep-
tion is where a change of drainage may have introduced material
derived from regions outside the creek basin. In nearly all parts of
Alaska the placer gold owes its present position entirely to the erosion
of the bed rock in which it was formerly disseminated, and to the sort-
ing action of water and gravity, which has brought about its pres-
ent concentrated form. This elementary principle is here emphasized
because it is not uncommon to find, even among well-informed men, a
tendency to entirely ignore the very simple facts, and to regard placers
as the result of glacial action, or as having had a still more cataclysmic
origin. As a matter of fact, all of the placers of Alaska, except a few
near the southern coast, are outside of the limit of former glacial
activity.
As has been stated, the gold of the placers has its source in small
veins and stringers in the bed rock or was disseminated in mineralized
zones. The facts now obtainable indicate that the outlook for future
quartz mining in the placer fields of the interior of Alaska is not hope-
ful. While it is by no means impossible that larger gold-bearing
veins carrying commercial values may be found, it seems probable
that most of the placer gold has been freed from bed rock, where it
was more or less widely disseminated, and subsequently concentrated
brooks.] PLACER GOLD MINING IN ALASKA. 43
by the sorting action of water. It is not uncommon to hear Alaskan
prospectors speak of the "mother lode," as if the gold had all been
derived from one lode or zone of mineralization. Of this there is no
evidence whatever. In considering the question of quartz veins in
the placer fields, it should be remembered that the dense coating of
moss makes bed-rock prospecting difficult and uncertain.
The auriferous deposits from which the placer gold is derived occur
in metamorphic rocks of various kinds. They include schists of vari-
ous types, phyllites, limestones, quartzites, and altered igneous rocks.
Such metamorphic terranes find a wide development in Alaska, and
probably occur in a number of different horizons. The study of the
geology of Alaska has not progressed far enough to permit of correla-
tions, or of definite statement in regard to the age of the metamorphic
terranes or their structural relations. The mineralized metamorphic
beds of southeastern Alaska are probably Mesozoic and older. Those
of the Yukon are chiefly, if not entirely, pre-Carboniferous, and those
of the Seward Peninsula are chiefly Paleozoic. Within the zone which
\ has been designated as the one in which gold placers have been found,
there are many large areas of these metamorphic rocks. These form
belts which are not by any means continuous, as they are interrupted
b ; areas of younger Mesozoic and Tertiary terranes. It has also been
shown that they probably belong to widely different horizons. Broadly
speaking, the mineral-bearing horizons of southeastern Alaska can be
placed in one group, and those of the Yukon Basin and of the Nome
\ region in another. It will remain for future studies to determine the
relation between these two belts.
The age of intrusion of the mineral-bearing solutions is largely an
unsolved problem. In the coastal belt of southeastern Alaska the
mineralization took place probably in Mesozoic time, while in the
Yukon region it was probably considerably earlier. The studies thus
far made indicate that the mineralization accompanied disturbances
of the strata, either by deformation or by igneous intrusions, or both,
which were rather local in their effect. They seem to be closeby
affiliated to igneous rocks which are everywhere found in the regions
of mineralization.
The studies of the alluvial gold deposits of Alaska have shown that
'mode of formation and concentration are the determining factors
of the richness of the placer deposits. The writer has elsewhere a
emphasized this fact in regard to Nome placers, and more recent
observations convince him that it is also applicable to the gold deposits
of the Yukon. In the simplest form of placers the gold is washed from
the parent rock and concentrated in the beds of the streams, mingled
with other detrital material Such placers have been exploited in
many localities and have been found to be important gold producers.
a Reconnaissance ot the Cape Nome and Norton Bay Regions, U. S. Geological Survey, 1901, pp.
L44-151.
44 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
It is probable, however, that nearly all the very rich placers owe their
origin to secondary concentration. This has been brought about by
the erosion and dissection of an older placer and the reconcentration
of the gold contained therein. This process of double sorting is
probably the chief cause of the bonanzas which are not uncommon in
the Alaskan placer mines, and will probably also account for those
irregularities of distribution of the placer gold often within a single
topographic basin, which are so puzzling to the miner.
A common form of the enrichment is the dissection of an auriferous
gravel bench of the slopes of a stream valley by a tributaiy stream.
This tributary stream carries the gold derived from the bench to the
main stream, where it is mingled with the gold of the main stream,
and causes an enrichment of the placers located at and below the
junction of the two streams. In some instances the gravels of an
older drainage system, lying often at considerable altitudes above the
present stream floors, are dissected by the present waterways, and
the gold contained in the older gravels is thus resorted and recon-
centrated. Instances of this kind are not uncommon in the Nome
region, and have been observed by the writer in the Rampart region
of the Yukon.
Another form of concentration is that by wave action. In this
mode of enrichment the waves concentrate the gold which lias been
deposited in the gravels of the coastal plains. It is in such a manner
that the marvelously rich beach placers of Nome were formed.
It seems probable that the study of these questions of reconcentra- !
tion will \ct yield important commercial results, even in the better
known mining districts of Alaska. A practical application of these
principles would suggest, that the prospector seek to trace old drain-
age channels and pay special attention to the junction of these with
the present streams.
SEWARD PENINSULA.
During the last season the climatic conditions in the Seward Penin-
sula were not, by any means, favorable to a large gold output. While
there were heavy rains in the fall, the months of July and August
were very dry, and hence but little sluicing was done. It should be
noted, however, that the experience of the last three years indicates
that such meteorological conditions are to be expected every third
year, if not every other year. The output, therefore, is probably not
nearly as large as it would have been had water been available early
in the season. Moreover, much of the development was in the nature
of dead work in p reparation for extensive operations during the pres-
ent season. Ditches were dug, roads built, and pumping plants estab-
lished, which will greatly accelerate the prosperity of the district and,
undoubtedly, will materially increase its gold production. The prob-
lem of transportation is still a serious one. Under the best conditions
the landing of heavy machinery and supplies on the Nome beach is a
brooks] PLACER GOLD MINING IN ALASKA. 45
difficult task, but during stormy weather it becomes well nigh impos-
sible. After heavy machinery has been landed it is still a grave
problem how to transport it from the coast to the mines. This involves
the building of roads and, in some cases, the dredging of rivers.
The region immediately tributary to Nome is better prepared to
meet these conditions than the more isolated camps. The narrow-
gage railroad, which runs from the beach to the head of Anvil Creek,
makes the transportation problem at that particular locality a simple
one. Roads, moreover, have been built to adjacent creeks from the
railway, so it is now possible to handle heavy machinery.
In Anvil Creek probably the most important development was in
the auriferous gravels of the benches which are found on both sides
of the valley. This gave a new impetus to mining, for the gravels in
the creek bed itself were nearly all run through the sluices during
the two previous years. The high-bench gravels, lying at altitudes
of 500 to 800 feet above the sea, which were discovered in 1900, still
continued to be developed. Some of these have great depth, and the
extraction of the gold has been a difficult problem.
The so-called "tundra placers," or more properly coastal plain
placers, still continue to be worked, but their development has not
been commensurate to their probable importance. It seems more
than likely that the gravels which make up this coastal plain, in
many places, car^ workable placers. These may be, in part, old sea
beaches, or may be the channels of abandoned streams and rivers.
The problem of handling large quantities of these gravels, which are
a few feet above and below sea level, has not yet been solved. Most
of the mining has been confined to shallow pits and trenches, and
i the operations have been hampered by lack of means to handle the
surface water. The extraction of the gold has been largely accom-
plished by use of hand rockers. Winter mining has been carried on
by means of petroleum and coal-burning steam thawers. With the
aid of the thawer a pit is sunk to the pay streak, which is followed by
drifting. The gold-bearing gravel is then hoisted to the surface and
washed out during the open summer season. It is of interest to note
that drills have been successfully employed in prospecting for the
pay streak in the coastal plain gravels. The ground underneath the
thick coating of vegetation is frozen throughout the year, but thaws
to a depth of 2 or more feet where this coating is removed. If an
economic method of mining these gravels in a large way and of
extracting their gold contents could be devised, large profits would
undoubtedly be made.
During the four years which have elapsed since the discovery of
the Nome placers, the gold seeker has gradually worked his way
inland, so that now there has been some prospecting done over nearly
the entire Seward Peninsula.
During the last season gold mining was going on in the Nome region
proper, in the Solomon and Eldorado River region, on the streams
46 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
tributary from the south to the Kruzgamepa in the Kuzitrin basin,
and on streams tributary to the Niukluk. All of these belong to the
Bering Sea drainage. A number of the streams which are tributary
to Port Clarence were also found to carry commercial values. Some
developments of placers on streams flowing northward to the Arctic
Ocean have been made. None of the northerly flowing streams have,
as yet, been found to be as rich as those of the older and better known
districts of the South. Many have, however, produced gold in com-
mercial quantities, and with further developments will probably
become important producers.
What has been said of the Nome region proper applies in large meas-
ure to the other creeks in the region. In nearly every case where dis-
coveries have been made the first developments are along the present
stream channels. When these are worked out, which does not take
long where the streams are small, the prospectors turn their attention
to the benches and terraces, and these often yield good returns. In
some cases placers have been practically abandoned which it seems to
the writer u\ay still carry gold in commercial quantities. Such may
prove to be the case in districts like the Kugruk, where the miners have
worked out the small creek beds and have neglected to thoroughly
prospect the terraces and benches. Of special interest is the very
large increase in the output of Ophir Creek, a northern tributary of
the Niukluk. This stream was one of the first on which gold was
discovered in the Seward Peninsula, and for several years was spas-
modically worked, but it is only since the introduction of systematic
methods of mining and extraction that Ophir Creek has become one
of the largest producers of the region. It has been estimated that its
production during the last year was upward of 11,000,000. These
facts augur well for the future of the Seward Peninsula placer fields.
It seems probable that there are other streams which may go through
a history similar to that of Ophir Creek.
YUKON REGION.
Mining has been going on in the Upper Koyukuk Basin since the
summer of 1899, and the basin has probably produced from $100,000
to $200,000 annually. This money has been chiefly taken out of half
a dozen creeks which are tributary to the Upper Koyukuk about (300
miles from its mouth. About 500 miles of this distance can be made
by river steamer. During the last season many miners returning
from the Koyukuk seemed to be rather discouraged. There seems to be
no question that there are workable placer fields in the district, but
the high price of provisions and the short season have prevented many
of these from being worked at a profit. With water transportation
within a short distance of these placer mines there seems to be no
reason why supplies should not be as cheap as on the Yukon. It is
to be hoped that there will be a reduction in the cost of living, which
brooks] PLACER GOLD MINING IN ALASKA. 47
will enable developments to continue in this region, which lies north
of the Arctic Circle.
Rampart is a small settlement on the Yukon about 1,000 miles from
tide water. It has tributary to it a number of camps which have long
produced some gold, and these are still producing, but not in great
quantity. The important development of the season is that of Glenn
Gulch, about 30 miles south of Rampart. Glenn Gulch is tributary to
Baker Creek, which flows into the Tanana about 100 miles from the
Yukon. The gulch itself has proved phenomenally rich, and a number
of other streams in this region give promise of becoming producers. A
description of this region by Mr. Collier will be found elsewhere in
this volume.
The region lying between the Yukon and the Tanana is one in which
many gold-producing creeks have been found. The earliest discov-
eries were all made on the Yukon side of the divide, but since 1898
much prospecting has been done on strems tributaries to the Tanana
from the north. In only a few cases have these yielded anything of
value, and, as far as known to the writer, the gold-producing creeks
are all tributary to the lower 200 miles of the Tanana. Little infor-
mation is available in regard to this region, but it is stated that consid-
erable gold has been taken out of streams which flow into the Chena
River, which joins the Tanana about 300 miles from the Yukon. The
daity press has recently contained references to phenomenally rich
placers found somewhere in this region. Pedro Creek, whose loca-
tion is not given, is said to have been found to be very rich, but these
rumors have not received confirmation.
The Birch Creek region embraces the headwaters of the stream of
the same name, tributary to the Yukon near the Arctic Circle. It is
one of the oldest placer districts of the Yukon, and still continues to
produce some gold. With the cheapening of provisions on the Yukon
the placer mining on some of the older creeks took a new lease of
life, and such is the case on Birch Creek. Low-grade placers are now
being developed in the Birch Creek Basin, which could not be eco-
nomically developed under the old conditions. During the winter of
1901-2 much mining machinery was taken into the district. It is
reported that the district contains extensive deposits of low-grade
placers, which it is proposed to mine with refined methods.
Fortymile River enters the Yukon 20 miles above the international
boundary. That its bars carry gold has been known for the last fif-
teen years, and streams tributary to it have been important gold pro-
ducers for the last eight years. Many of these streams are still being
worked, and a few new ones have been discovered. In many instances
bench claims are being developed. While the gold production of the
district has not been large, the placers are by no means exhausted,
and it is possible that important discoveries will still be made.
During the last year placer mining has been done on a number of
small creeks tributary to the Upper Yukon. On Boundary Creek, 12
48 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
miles above Eagle, two or three claims were worked last summer. In
the immediate vicinity, on American Creek and Colorado Creek, tribu-
tary to Mission Creek, some mining was also done. Seventyinile
River was also the scene of mining operations, about 15 miles from
the Yukon, and one hydraulic plant was run. On Fourth of July
Creek, 50 miles below Eagle, 12 men were at work on claims last
summer. Three claims on Coal Creek and several on Woodchopper
Creek, 140 miles below, also received some development of their
placers.
COPPER RIVER REGION.
Gold has been found in commercial quantities at two widely sepa-
rated places in the Copper River Basin. The Chistochina gold field,
which has produced nearly all the gold of the region, is in the drain-
age basin of a river of the same name which joins the Copper about
200 miles from the coast. This district contains several gold-producing
creeks which can be reached by trail from Valdes. Gold placers have
also been found at a number of widely scattered localities in the Cop-
per River Basin. A description of this district by Mr. Mendenhall
will be found elsewhere in this volume.
COOK INLET REGION.
The region lying adjacent to t he head of Cook Inlet and about
Turnagain Arm has long been a small gold producer. No very rich
placers have been found, but the accessibility of the district made
it possible to develop deposits which could not have been worked at
a profit if located in the interior. Hydraulic mining has been going
on in a small way lor a number of years, and more elaborate plants are
being installed. The open season of Cook Inlet comprises about five
months, which gives the district two months' advantage, or more, over
that of the interior, or of Nome. The developments of the last year
have been rather in the way of introducing more refined methods of
mining rather than of new discoveries.
PORCUPINE DISTRICT.
This is a small placer-gold district about 30 miles from Pyramid
Harbor, an embayment of Lynn Canal, whence it is easily accessible
bjr wagon road. It lies chiefly within the catchment basin of Porcu-
pine Creek, a small stream which enters the Klehini about 20 miles
above its junction with the Chilkat. The placers are so situated that
they offer peculiarly difficult conditions for mining. They occur
largely in small glacial benches and in the stream bed of Porcupine
Creek, which has a very sharp rock-cut valley. To work these pla-
cers it has been necessary to divert the water of the stream by means
of sluices, to give access to the gravels in the creek bed. This involved
a large expenditure of time and money. During the last season these
developments were still going on, and the district has not yet reached
a large productive stage.
THE GLENN CREEK GOLD MINING DISTRICT, ALASKA."
By Arthur J. Collier.
INTRODUCTION.
Glenn Creek is a small tributary of Baker Creek, a large stream
which enters the Tanana from the north, about 80 miles from the
Yukon. The mining camp there located is the site of the most
important discovery of placer gold made in the interior of Alaska dur-
ing the seasons of 1901 and 1902. This camp is about 28 miles in a
direct line nearly due south of the town of Rampart, on the Ynkon
River. Rampart is the distributing point for Glenn Creek, as well as
for several older mining camps, and has a population of about 300.
It is approximately 1,000 miles from the mouth of the Yukon and 600
miles from Dawson, and can be reached by river steamer from Daw-
son in about three days, or from St. Michael in about a week.
The Glenn Creek trail from Rampart follows up Big Minook Creek
for a distance of 25 miles to its head, then crosses a divide having an
elevation of about 1,700 feet above the river and drops down to the
Glenn Creek Camp, which has an elevation of about 800 feet above the
Yukon. The distance from Rampart to Glenn Creek by this trail is
about 30 miles, and along it the footing is so soft that two days are
usually required in summer to make the trip comfortably, either by
walking or by riding.
The camp is near Baker Creek, 18 miles from its junction witli the
Tanana River, at which place a small trading post has been estab-
lished, which can be reached by steamer coming up the Tanana from
the Yukon. Baker Creek is navigable for canoes up to within a few
miles of the Glenn Creek Camp, but the trail from Glenn Creek to
the Tanana is reported to be very swampy.
Since only five days could be spent by the writer in making the trip
from Rampart to Glenn Creek and return, the information obtained
is necessarily meager and the results are in many respects unsatis-
factory.
"This paper is an abstract of a more extensive report, now in preparation.
Bull. 213—03 4 49
50 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
The Glenn Creek mining camp lies on the northern edge of an
extensive lowland basin known as the Baker Flats. These flats,
opposite Glenn Creek, have a width from north to south of from 7 to
10 miles, but their greatest extension is in an east-west direction.
This broad lowland is a depression which has been deeply filled b}^
fluvial deposits. Near the mouth of Eureka Creek a prospect hole
penetrated 65 feet of gravel without reaching bed rock. Along its
southern margin there is a range of low, flat- topped hills, which sep-
arate it from the great lowland of the Lower Tanana, and through
this range Baker Creek flows in a narrow gap. The creek forks just
above this gap, and the eastern fork, which is the larger, is called the
Hootlenana, while the western fork retains the name Baker Creek.
Eureka Creek, which receives a large part of the drainage from the
northern margin of the flats, enters Baker Creek near these forks.
A broad bench was observed 100 to 200 feet above the valley level at
the northern margin of Baker Flat. The gold placers thus far dis-
covered are confined to a number of small creeks flowing into the
Baker Flats from the north, and in the immediate vicinity of the Glenn
Creek camp these streams are known lobe gold-bearing only Avhere
they cnl across the above-mentioned bench. Several miles to the
east Pioneer Creek and other tributaries of the Hootlenana are gold
bearing and it is probable that the gold-bearing belt extends about
20 miles along the north side of the Baker Flats, but it was notexam-
ined by the writer except in the immediate vicinity of Glenn Creek.
Active mining has been in progress on Minook Creek, near Ram-
part, since 1 sin;, and the creek was probably prospected as early as
1882. From Minook Creek as a center prospectors have extended
their search across the divides in all directions. In the summer of
1901 colors of gold were found on Eureka Creek and mining was
attempted. Gold in paying quantities was discovered on Glenn Creek
July 24, L901, by a miner who had a contract for supplying wood at
the mine on Eureka Creek. Colors of gold, but not in paying quan-
tities, had already been discovered on Rhode Island and Omega creeks
in this region.
GEOLOGY.
In the vicinity of Rampart on the Yukon the bed rock consists of
a series of volcanic rocks interbedded with siliceous slates and lime-
stones, called by Spurr the Rampart series. a From fossils collected
last season near Circle this terrane is believed to be of Devonian age.
About 8 miles south of Rampart a series of siliceous slates, quartz-
ites, and schists was found, which continues with more or less varia-
tion across the divide to Glenn Creek. The relation of the Rampart
series to this slate and schist series could not be determined with cer-
o Spurr, J. E., Geology of the Yukon gold district, Alaska: Eighteenth Ann. Rept. U. S. Geol.
Survey, Pt. II, pp. 155-169.
collier.] GLENN CREEK GOLD MINING DISTRICT, ALASKA. 51
tainty, but the evidence indicates that the Rampart series is younger.
If this be true, the schist series of the upper part of Minook Creek
and of Glenn Creek may be correlated with either the Fortymile or
the Birch Creek series of Spurr. No evidence of faulting or intru-
sions of granite in this series, as indicated by Spurr, a was seen along
Minook Creek by the writer. The rocks contain small quartz veins
and stringers in many places, and the debris from them includes peb-
bles of igneous material other than granite, suggesting the presence
of intrusions of various kinds.
A few specimens of the sedimentary rocks have been examined micro-
scopically. These vary in degree of alteration, in some cases being
garnetiferous mica-schists, in others quartzites consisting of inter-
locking quartz grains. All the specimens examined contained more
or less muscovite. Microscopically these rocks resemble the Birch
Creek series as described by Spurr.6 A similar series of schists
occurring at many places along the Tanana River c has been described
by Brooks under the name Tanana schists. They outcrop for some
distance along the Tanana below the mouth of Baker Creek, making
it probable that the schist series forms a continuous area from Minook
Creek, 8 miles above Rampart, to the Tanana below Baker Creek.
These schists have been correlated by Brooks d with the Birch Creek-
Fortymile series of Spurr.
DESCRIPTION OF PLACERS.
Glenn Creek is a small stream, in summer carrying less than a
sluice-head of water, which rises in a bench on the north side of
Baker Flats and flows southward to the flats. The creek occupies a
broad, shallow depression less than 50 feet deep, which makes a hardly
noticeable break in the topography.
About one-half mile west of Glenn Creek, Gold Run, a still smaller
stream, also flows southward to Baker Flats, and about one-half mile
farther west Rhode Island Creek, a larger stream, has cut a deep
trench nearly to the local base-level of Baker Flats. About a mile
east of Glenn Creek, Eureka, a large creek, enters Baker Flats, also
from the north, occupying a deep, well-marked trench. Each of the
creeks named above carries placer gold in paying quantities for a dis-
tance of about a mile, and the bench between Glenn Creek and Gold
Run also has been found in places to be covered with gold-bearing
gravel rich enough for exploitation.
The productive placers of Glenn Creek are confined to four or five
claims within a mile of the head of the creek. In this distance the
creek bed has a fall of about 5 feet in 100.
"Geology of the Yukon gold district: Eighteenth Ann. Rept. U. S. Geol. Survey, Pt III,
PI. XXXVIII.
^ Ibid., p. 144.
cSee Reconnaissance in the Tanana and White River basins, Alaska, 1898: Twentieth Ann.
Rept. U S. Geol. Survey, Pt. VII, map 24.
"Ibid., pp. 468 and 469.
52 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
On Discovery Claim, at the edge of Baker Flats and at the lower
end of the productive part of the creek, a prospect hole 40 feet deep
failed to reach bed rock. In all the claims above Discovery bed rock
can be reached at a depth of from 5 to 20 feet. The bed rock is a
schist, usually called slate by the miners. It ranges in color from
dark blue to gray, and is often graphitic. It represents a rather
argillaceous sediment which has been subjected to only a moderate
degree of metamorphism, sufficient to produce many metamorphic
minerals, but not to entirely destroy the original structure. This bed
rock is often cut by stringers of quartz, which are reported to strike
nearly east and west. These stringers are white and at the outcrop
are decomposed along with the remainder of the bed rock, which is
often so disintegrated that it can be shoveled out like fine gravel.
The width of the pay streak varies from 20 to 60 feet. In one place
a pay streak 7 feet thick is reported. On the lower claims the pay
streak is near the surface, so that summer work "by stripping and
shoveling" is possible. In the Tipper claims the pay streak is found
below several feet of muck and barren gravel, and is mined with steam
thawers in winter and washed in the spring. Early in August, when
the creek was examined, only one claim, known as Claim No. 2, was
working. The others were shut down because the dumps had already
been sluiced. On Claim No. 2 miners were shoveling into the sluice
boxes directly from the pay streak. It was impossible to see the bed
rock in place, or to see a full section of the gravel from the surface
down in the deeper workings. The pay gravel consists of angular
fragments of schisl and a small amount of vein quartz, with occasional
rounded bowlders of a basic, igneous rock. The gold is not evenly
distributed in the pay streak. Sometimes the best pay is found on
the surface of a layer of decomposed bed rock. " Stringers" of gold
on this bed rock were found carrying $10 to $35 to the pan. These
"stringers" are lines of gold parallel with the bed rock, which look
when uncovered as if the rock had been sprinkled with gold. On
some of the claims values are reported to have been found to a depth
of 2^ feet in a hard, blocky bed rock. On some of the lower claims
above the bed rock there is a waxy clay, called by the miners "gumbo,"
which is probably decomposed rock in situ. This clay ordinarily does
not carry gold, but on one of the upper claims a gumbo ball is reported
to have carried $1 in fine colors.
In the summer of 1901, after the discovery, a small amount of gold
was taken out before the end of the season. During the winter of
1901-2 a large part of the pay streak was taken out by drifting, and
the dumps were washed in the following spring. It was estimated by
a representative of the Eagle Mining Company, which owns several of
the claims, that the creek had produced approximately $150,000 prior
to the 1st of August, 1902.
Gold Run occupies a very slight depression parallel with Glenn
collier] GLENN CREEK GOLD MINING DISTRICT, ALASKA. 53
Creek and about one-half mile to the westward. It is a tributary of
Rhode Island Creek, into which it empties a short distance above the
Baker Flats. Claim No. 1 of Gold Run joins with Claim No. 3, Rhode
Island. The bed rock consists of schists similar to those on Glenn
Creek. It is described by the prospectors as a "blocky schist."
The pay gravel consists of angular fragments of this bed rock, which
show very little if any rounding, such as would be expected in chan-
nel-washed gravel. The prospecting shows a pay streak from 12 to
40 feet wide. At the lower end of Claim No. 1 the pay streak, which
varies greatly in thickness, is divided by a reef. Beyond the limits
of the pay streak the gravels continue to show prospects of gold.
The pay streak in one instance is reported to be 3 feet thick and to
underlie 11 feet of muck and barren gravel.
Very little gold has as yet been taken from this creek, though the
prospecting shows a distribution of gold somewhat similar to that on
Glenn Creek. Preparations were being made for mining on five claims
on this creek during the winter of 1902-3. During the winter of
1901-2 the pay streak from an area 15 by 20 feet was mined out. This
dump has yielded $1,000, but has not all been washed.
It was proposed to work the creek during the winter of 1902-3 with
steam thawers according to the following plan: Shafts were to be
sunk to bed rock, a depth of 10 to 15 feet. From the foot of each
shaft the pay streak would be drifted on for a distance of about 40
feet, with a cover of 10 or 11 feet. It was regarded as impracticable
to drift farther than this on account of the difficulty of carrying steam
pipes and moving the pay dirt to the foot of the shaft and keeping the
gangway open. Steam thawers, if properly managed, are more eco-
nomical in mining frozen ground than the old method of "burning"
with wood, for the reason that the steam points can be driven directly
into the ground where thawing is needed, and the pay dirt can be
mined immediately as it is thawed, whereas by the old method work
is interrupted while the fire is burning and, at best, a night's burning
will not thaw more than 1 foot of gravel.
Gold Run does not carry sufficient water for sluicing after the snows
have melted in summer, and mining operations will necessarily be
suspended during the summer months.
Rhode Island Creek is larger than either Glenn or Gold Run and
flows in a well-marked valley cut about 100 feet below the level of the
bench on which the streams described are located.
The bed rock consists of schists similar to those at Glenn Creek,
except that it probably contains more graphitic schist than at Glenn
Creek. The strike of the bed rock is reported to be northwest and
southeast. Stringers of quartz have not been found in it.
The gravel consists of more or less angular fragments of schist sim-
ilar to that at Glenn Creek, except that graphitic schists are more
common, as well as pebbles and bowlders of igneous rocks. Two types
54 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
of igneous rocks were recognized, one of which is a green, compact
rock, probably an altered intrusive from the schist series, while the
other is an unaltered rock of very basic type. The creek has not been
thoroughly prospected on account of inundation of the prospect holes.
In the middle of the creek, bed rock has not been reached, but good
prospects have been found on the rims. At Claim No. 5, about one-
fourth of a mile above the mouth of Gold Run, a shaft was being sunk
on the left limit of the pay streak, with a view to draining the bed
rock with a steam pump. This shaft penetrated, to a depth of 12 feet,
broken bed rock similar to that on Glenn Creek. The pa}^ streak
here is believed to be from 50 to 60 feet wide. The average yield from
a number of pans taken from the pay streak was reported to be 11
cents. About one-half mile above this place mining was in progress
on a claim on which the bed rock has been partially drained. The
claim had not been fully crosscut, but it was believed to have a pay
streak 60 feet wide. Where it has been prospected the pay streak is 2
feet thick and underlies 6 feet of muck and barren gravel. Twenty-
five and 50 cent pans have been obtained from this pay streak. The
owners of this mine were attempting to work it in summer, stripping
off the muck and barren gravel and shoveling the pay dirt into sluice
boxes.
On the bench between Glenn Creek and Gold Run have been found
shallow gravels carrying placer gold in paying quantities. It is
reported that generally on this bench the bed rock is covered by a
layer of clay, probably derived from the decomposition of the bed
rock. This clay carries a little gold, the coarsest being near the
surface. The gold does not extend far up the hill to the northward,
but can be traced down the hill for several thousand feet. Two
claims have been located on which gold is found in paying quantities.
At the upper end of the upper claim the excavation shows 6 inches
of reddish clay soil overlying 1 foot of gravel consisting of clay mixed
with small pieces of gray schist similar to the bed rock, but containing
occasionally large, well-rounded pieces of a basic igneous rock. This
gravel is the pay streak and rests on bed rock. At the lower end of
this excavation, about 200 feet from the point described, 4 feet of
nearly barren gravel wash overlie the pay streak, which consists of 1
foot of gravel made up of broken fragments of schist bed rock. The
pay streak has a width of 65 feet. Beyond the pay, however, on the
south side, a prospect hole was sunk through 4£ feet of broken schist
debris, showing little, if any, gravel wash. Colors of gold were found
near the bottom of this hole. On this claim the attitude of the gravel
indicates a current from the north.
The lower claim has been prospected at a point one-fourth mile
southeast of the upper claim. Here prospect holes show the gravel
to be from 6 to 8 feet thick. The position of the pebbles indicates
deposition by a current flowing nearly east. The gravel contains a
collier.] GLENN CREEK GOLD MINING DISTRICT, ALASKA. 55
few large, round bowlders of igneous rock. It is claimed that this
gravel from the surface down will pay for washing, and that the pay
goes into the bed rock to a depth of 1 foot. The pay streak is more
than 100 feet wide.
The gold on these claims is comparatively coarse, nuggets as large
as one dollar being common, though the average pieces are smaller
than one cent. On the lower claim the pieces of gold are probably
finer than on the upper. The pay streak at the former place is
reported to average 6 cents to the pan. The gold nuggets have a
rough surface, showing that they have not traveled far.
At the upper claim some sluicing has been done with water col-
lected in a system of ditches on the surface of the bench. These
ditches provide a limited amount of water when the snow is going off
in the spring and after heavy rains in the fall. A ditch about 2 miles
long has recently been dug to bring water from Rhode Island Creek,
but except in a rainy season the water from this source will probably
be insufficient for sluicing.
Mining has been in progress on Eureka Creek, 1 or 2 miles east of
Glenn Creek, for the last two years. These mines have not been
great producers of gold, and the writer was unable to visit them.
They are reported to be confined to a section of the creek bed 1 mile
long, and situated nearly opposite the mines on Glenn Creek.
Good prospects of gold are reported from Omega Creek and McKin-
ley Creek in this region, and within a few miles of Glenn Creek.
Their exact location is not known and they were not examined by
the writer.
During the last season gold prospects were found on Pioneer Creek
and several other northern tributaries of the Hootlenana. These lie
east of Glenn Creek and probably within 10 miles of it.
One prospect hole was sunk to a depth of 65 feet in the gravels of
Baker Flats. While no pay streak has been located, colors of gold
are reported. It will require further prospecting to show whether
these gravels are workable as gold placers.
On Minook Creek and on its several tributaries, known as Hunter,
Little Minook, Rubj^, and Slate creeks, placer mines were in opera-
tion last summer.
SUMMARY.
In the vicinity of Glenn Creek the known gold placers are confined
to the creeks and benches within an area about 1 mile wide and 2 to
3 miles long, lying parallel to the north side of the Baker Flats. This
area coincides roughly with the limits of a broad bench cut on bed
rock, 100 to 200 feet above the level of the lowland. Two of the
creeks carrying placer gold rise within this bench, while two larger
ones are gold bearing only where they cross it.
The bench generally is covered by a soil derived from the bed rock
56 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
in situ, but in some places bodies of shallow gravel occur. These grav-
els consist principally of angular material derived from the immediate
bed rock, but they contain some bowlders and pebbles which have
undoubtedly been transported. The gravels of the creeks and gulches
incised in the bench are essentially similar to those found on the
bench.
From the evidence in hand, it seems at least possible that the low-
land of the Baker Flats is the bed of an extinct lake and that the
broad bench at Glenn Creek is in part a beach and in part a local
peneplain produced at the base-level of this lake while it existed.
The mixture of local and transported material is readily explained in
this way, either by water action alone or by floating ice.
The pieces of gold found here are apparently not greatly water-
worn, and have probably not been carried far from their original posi-
tion in the bed rock. The bed rock of the gold-bearing area consists
of schist, belonging to a series which has an extensive distribution
in this region. On Glenn Creek, however, a system of quartz string-
ers striking parallel with the longer dimension of the gold-bearing
area has been noted, making it seem probable that there is a zone of
mineralization in the bed rock underlying the gold-bearing area.
The information at present available regarding the geology and
physiography of this region is too meager to Avarrant any definite con-
clusions as to the origin of the placers, but the following explanation,
which is believed to agree with the facts as far as known, is advanced
tentatively :
The gold at Glenn Creek has been derived from a zone of mineral-
ization in the bed rock north of Baker Flats. This zone extends east-
ward for 10 or 12 miles, to the northern tributaries of the Hootlenana,
on which placers have recently been found, but is less than a mile in
width. As the bed rock was eroded, the gold from this mineralized
zone was concentrated by both wave and stream action along the mar-
gin of the old Baker Lake. By the draining of this lake the old beach
was left as a high bench, and the gold from it has been partly recon-
centrated in the beds of recent streams, to make the creek placers,
while a part of the original beach deposit remains in the form of
bench placers.
GOLD AND PYRITE DEPOSITS OF THE DAHLONEGA DISTRICT,
GEORGIA.
By Edwin C. Eckel.
Field work in the Dahlonega gold district of Georgia was carried
on by the writer during September, 1902, under the direction of
Dr. C. W. Hayes. While this field work was merely of reconnais-
sance character, preliminary to the commencement of folio mapping
in the area, it developed certain features of considerable importance
in connection with the gold deposits of the district. A preliminary
report on this work, with maps, will be issued this }7ear as a survey
bulletin, while a brief statement of the principal results as regards the
gold deposits has been published in a recent issue of the Engineering
and Mining Journal. That portion of the present paper which relates
to the gold deposits is essentially a reprint of that last noted, though it
contains certain minor changes which affect the wording rather than
the conclusions.
LITERATURE OF THE SUBJECT.
Though numerous references to the Dahlonega district are to be
found in geological and mining literature, the following six papers
will suffice to give the reader a good idea of the geology and mining
industr}^ of the region. In 1895 Dr. George F. Becker published, in
the Sixteenth Annual Report of the United States Geological Survey,
Part III, pp. 251-331, a valuable account of a "Reconnaissance of the
gold fields of the southern Appalachians. " In the same year Messrs.
Nitze and Wilkens published, in the Transactions of the American
Institute of Mining Engineers, Vol. XXV, a paper on ' ' The present con-
dition of gold mining in the southern Appalachians." These papers
are still the best summaries of the geological features of the Appala-
chian gold fields, and of the relations of the ore deposits. Dr. W. S.
Yeates published in 1896, as Bulletin 4A of the Georgia Geological
Survey, a "Preliminary report on a part of the gold deposits of
Georgia." This volume, by Yeates, McCallie, and King, contains
much interesting detail concerning both the mines and the mining
history of the region. The principal advances in Dahlonega mining
practice since that date are well described in the three following
papers which have appeared in the Engineering and Mining Journal:
57
58 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bi^l. 313.
"The Dahlonega Consolidated Gold Mining Company's plant," by
W. Colvin, August 17, 1901; "The Crown Mountain gold mine and
mill," by H. V. Maxwell, September 21, 1901, and "Gold dredging in
north Georgia," by the same author, November 2, 1901.
GENERAL GEOLOGY.
All the rocks of the Dahlonega district of Lumpkin County, Ga.,
are highly crystalline, no series of indisputably sedimentary origin
occurring in the immediate vicinity. The rocks dip usually at a
high angle to the east. The strike is, in general, about N. 60° E.,
but at the northern end of Findley Ridge this changes abruptly to
N. 5° W. In consequence of this change of strike the mines, as
would be shown on a mine map of the district, occur along two lines
meeting almost at a right angle. Four rock types occurring in the
district are sufficiently well marked and areally important to be
separately described.
Mica-schists. — For convenience (ho normal rocks of the district
(excluding the doubtful feldspathic gneisses next described, and the
granites and diorite, which are undoubtedly of igneous origin) will
be grouped as mica-schists. More fresh material than is at present
available must be examined before finer distinctions can be profitably
made.
Though the decomposed outcrops seem, in general, to be highly
micaceous, examination of fresh material from several mine tunnels
seems to show that these "mica-schists" are prevailingly siliceous,
the mica being highly developed only along joint and shearing planes.
This highly siliceous character would seem to point toward a possible
sedimentary origin of at least part of these schists by metamorphism
from impure sandstones. This question, however, requires much
further investigation.
As to age, nothing occurs in the district which can be used as proof
of the absolute age of these rocks. Lacking such proof, they have
been generally regarded as pre-Cambrian, but possibly they are of
Cambrian or Lower Silurian age. As to relative age, it is certain that
they are the oldest rocks of the immediate district, with the possible
exception of certain feldspathic gneisses, which are next described
Feldspathic gneisses. — At several points in the area under consid-
eration highly feldspathic gneisses occur, notably in one northeast-
southwest trending ridge, parallel to and some miles east of the
Chestatee River. These rocks are well banded, some bands consist-
ing largely of mica and quartz, while others contain much feldspar.
It is possible that these feldspathic gneisses constitute a true rock
type, but at present the writer is inclined to believe that the more
feldspathic bands simply represent granitic material injected into a
preexisting mica-schist and subsequently sheared with it. In some oi
the larger bands of feldspathic material this derivation from granite
■
eokel] GOLD AND PYRITE OF DAHLONEGA DISTRICT, GA. 59
seems to be strongly indicated, but farther detailed study will be
necessary to determine this point.
Diorite. — Several large bodies of hornblende-schist occur in the area
under consideration, as well as in adjoining regions to the west and
south. In general, this rock is a fine-grained, highly sheared horn-
blende-schist, its schistosity being conformable to that of the mica-
schists by which it is inclosed. At several points a less metamorphosed
phase of this hornblende-schist is shown, and it seems certain that it
was derived from an intrusive diorite. In fresh specimens the diorite
| is a hard, tine-grained, greenish-black rock, occasionally spotted with
white feldspar. It weathers to a reddish yellow, and is locally termed
r brickbat," because, on weathering, it separates into rectangular
blocks, owing to the presence of three systems of joints. The diorite
appears to decay more readily than the mica-schists of the region;
and this ease of decomposition seems to have fixed the location and
direction of many of the valle3rs of the area. The hornblende-schist
is well shown in the court-house square at Dahlonega, and is exposed
in most of the mines in Findley Ridge. It is an igneous rock, cutting
the mica-schists; but it was intruded at an early period, and has been
made thoroughly schistose. In age it is therefore intermediate between
the mica-schists and the granite next to be described.
Granite. — A light-colored, coarse-grained granite is exposed at the
Mary Henry and Bennings mines, and also at several points west of
Dahlonega. It consists largely of quartz and white feldspar, with
some biotite. Near the Hand mine it is shown cutting across the
lamination of the hornblende-schist. It is evidently a comparatively
late igneous intrusive, having suffered little from shearing or faulting,
and it may be roughly correlated, in point of age, with the Villa Rica
granite described by Dr. C. W. Hayes as occurring in the Cartersville
and Marietta quadrangles.
THE GOLD ORES AND ORE DEPOSITS.
As is well known, the earliest gold mining done in the district was
on the placer deposits occurring along the various rivers and creeks.
Later the attention of miners was called to the fact that in many
places the decomposed rocks of the region carried gold, and, accord-
ingly, sluicing these decomposed rocks came into practice. It was
soon found, on working through the upper decomposed portions of
these rocks to the fresh hard rocks below, that the free-milling ore
found in the upper decomposed rock changed to sulphides in depth.
In handling these sulphides, stamp milling and amalgamation did not
recover a sufficiently large proportion of the assay values to justify
exploitation o f the deposits in hard rock. Chlorination of the sulphides
was then tried, and has succeeded to a limited extent.
The placer deposits of the district have undergone treatment many
Itimes, and in consequence few can now be profitably worked by ordi-
60 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
nary methods. Dredging the river bottoms is, however, still profitable,
and is carried on as explained by Mr. H. V. Maxwell in the interesting
paper cited above. In the present article the placer deposits will not
be further discussed, attention being confined to the gold-quartz veins
of the district.
From the point of view of the miner, the gold-quartz veins can be
separated into two distinct classes, requiring very different treatment,
both in the mine and in the mill. As is well known, the rocks in this
portion of the southern Appalachians are very deeply weathered, and
in many places solid rock does not occur within 100 feet of the surface. a
In this zone of decayed rock — which on the average includes the
upper 50 to 100 feet — both the country rock and the vein material are
disintegrated, and resemble sand or gravel in texture and consistency.
The two important effects to the miner of this deep weathering are
that (1) the ore itself is free milling, the pja-ite having altered to
limonite and released its gold; and (2) the entire mass of material
can be mined and treated exactly like a thick placer deposit, by
hydraulic mining. At present hydraulic mining is being carried on
extensively in the Crown Point, Singleton, and Tahloneka properties,
the material being washed into sluices by the giants and carried in
this manner direct to the mills.
In a proposition of this character such a combination of soft
material and free-milling ore renders the cost of mining and milling
very low, and even low-grade ores can be profitably worked. The
ease of working is, however, partly offset by the fact that a large
amount of worthless material is washed out by the giants and sent to
the mill along with the profitable matter.
As soon as the zone of weathered rock is passed in depth the work-
ings eneounter solid rock (mica-schists, etc.) containing fairly distinct
veins of gold-bearing quartz. In this hard material it is possible to
mine only the vein, thus reducing the handling of worthless material to
a minimum. This advantage over workings in weathered rock is, how-
ever, much overbalanced by the two considerations that in deep
mining in solid rock (1) the cost of mining, per ton of material moved,
is very much higher than in soft material, and (2) the ores no longer
carry ai^ very large proportion of free gold, for the pyrite is not
decomposed. Simple stamping and amalgamation is therefore insuffi-
cient, and some more expensive process must be substituted. Numer-
ous "secret processes" have been tried without success. Chlorination
is now practiced at two plants, but the results are not entirely
satisfactory.
Relations of the gold-ore deposits. — Since the visit of Dr. Becker to
this district, in 1894, the mine workings have been deepened, and in
a Becker suggested the use of the term "saprolite" for material such as this, which is the
product of rock decay in place. Unfortunately "saprohte " has, in the Dahlonega district, been
adopted by the miners and used in a sense entirely different from that intended by Becker. For
this reason the term will not be used in the present discussion.
eckei,.] GOLD AND PYRITE OF DAHLONEGA DISTRICT, GA. 61
consequence the relations of the ore deposits to the country rock can
be studied to better advantage than was possible at that date. The
most interesting feature developed by the recent work has been in
relation to the position of the ore deposits. The writer believes it can
now be accepted as proved that in the large majority of mines in the
Dahlonega district the more profitable and continuous veins occur
along the contact between the mica-schists and an igneous rock, the
igneous rock being either a granite or a sheared diorite. This occur-
rence was first pointed out to the writer by Gen. A. J. Warner, as
occurring in the mines on Findley Ridge, and was, on further exam-
ination, found to be the common type of occurrence throughout the
entire district. There are, it is true, exceptions to this rule, but they
are not numerous. In a few cases (Betz mine, etc.) a body of schist,
not in the immediate vicinity of an igneous rock, is so cut by minute
gold-bearing quartz veins as to permit the entire mass to be profitably
mined, while in other instances, as on the Walker property, a small
but rich gold-quartz vein occurs entirely within the schists.
The genetic relationships existing between the ore deposits and the
igneous rock, in the two cases presented (granite and diorite), are of
very different character. The diorite, as noted earlier in this paper,
was injected into the schists at a much earlier period than that dur-
ing which the ore deposits were formed. This is proved by the fact
that this diorite has been crushed and sheared to such an extent that
it now appears as a hornblende-schist, the schistosity of which con-
forms to. that of the normal mica-schists of the region; Avhile the gold-
bearing veins cut both diorites and mica-schists, and have suffered
very little from either folding or faulting. The fact that many promi-
nent gold-bearing veins occur along the contact between the diorite
and the mica-schists is not due, therefore, to any direct action of the
diorite considered as an igneous rock, but to the facts (a) that fissures
are most likely to be formed along the contact between two forma-
tions differing in hardness and rigidity, and (b) that such fissures,
minute at first, may have been enlarged by the solution of the
relatively unstable diorite.
With regard to those deposits which occur along the contact be-
tween granite and mica-schist the case is somewhat different. Here
the intrusion of the granite may possibly have some direct genetic
connection with the formation of the ore deposits. As noted above,
the granite is younger than the diorite, cutting the latter at several
points in the area; it shows little or no banding and has been rela-
tively little folded. At several points the granite shows slight band-
ing; at other points minor faults occur within it. Rock movements
have evidently occurred in the region since the intrusion of the
granite, but such movements have been slight compared to those
which occurred in the interval between the intrusion of the diorite
ind the intrusion of the granite, as is evidenced by the relative amount
)f shearing shown by the two rocks.
62 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
Age of the gold-ore deposits. — The statement has frequently been
made that the gold-bearing quartz veins of eastern United States are
of pre-Cambrian age. While this may be true of certain areas, there
seems to be little evidence anywhere in its favor. Gold-quartz veins
occur, on the other hand, in Ocoee (Cambro-Silurian) rocks in Georgia
and Tennessee, while in New York the three authenticated occurrences
of gold-quartz veins are all in rocks of Lower Silurian age.
In the Dahlonega district, even if the country rocks be regarded as
pre-Cambrian in age (which the writer would not be inclined to be
lieve), the structural relations of the ore deposits are such as to make
it certain that they are not pre-Cambrian. It is possible, indeed, that
the gold-quartz veins were not formed until late in the Paleozoic.
PYRITE DEPOSIT IN THE DAHLONEGA DISTRICT.
The most interesting development of the last year in the Dahlonega
district has been the opening of a large high-grade body of pyrite in
the vicinity of the town. The occurrence of this mineral in at least
one bod}^ of workable size has been known for some time, but until
1902 the deposit had not been opened up sufficiently to justify any
statement as to its value. During the last year, however, exploitation
has been carried far enough to permit some idea being formed as to
the size, uniformity, and grade of the deposit.
The writer visited the mine in September, 1902, in company with
Mr. N. P. Pratt, and the present description is the first based on an
actual examination of the workings, as access to the incline and tun
nels had been denied to all previous visitors.
The property of the Chestatee Pyrites Company is located aboul
6 miles from Dahlonega, in a direction a little north of east. The
openings are located on the south side of the Chestatee River, aboul
2 miles west of its junction with the Tessantee.
The outcrop of the pyrite body has a direction about N. 45° E.
while it dips at an angle of about 45° to the northwest. On examin
ing the stratigraphy it is found that in position, form, and associa
tions this pyrite deposit closely resembles the typical gold deposits 01
Dahlonega, as described on pages 59 to 61 of the present bulletin
The pyrite forms a "bedded" vein at this point, being conformable
to the quartzose mica-schists which overlie it on the west. The rod
adjoining the pyrite on the east, however, is of the same type of horn
blende-schist as that described above in connection with the Dah
lonega gold veins. As with those deposits, the pyrite body occurs
on the contact between a normal (and possibly sedimentary) mica
schist and a hornblende-schist, which is a much metamorphosee
igneous rock of early date.
The deposit has been thoroughly opened at two points, in additio
to the pits and trenches which have been dug in order to test the conf
tinuity of the deposit. The northeastern opening is a tunnel, drivei
eckel.] GOLD AND PYRITE OF DAHLONEGA DISTRICT, GA. 63
completely through the vein. Two drifts diverge from the tunnel at
right angles, both being run parallel to the trend of the vein. One
of the drifts is run on the western or hanging wall of the vein ; the
other on the foot wall. About 100 feet southwest of the tunnel open-
ing an incline has been sunk on the dip of the vein, a depth of 60
feet below the mouth level having been attained at the time of visit.
These workings, taken in connection with somewhat extensive
diamond-drill explorations and the examination of natural outcrops,
would seem to give a fair basis for calculation of the size of the
deposits. The outcrop extends for a distance of at least 2,000 feet
along the surface of the ground. Where it has been effectively cross-
cut by tunnels and incline, the pyrite body is shown to be about 30
feet in thickness, and trenches and drill borings would appear to
prove that its thickness at»no point along the 2,000 feet of exposure
falls below 20 feet. It has been followed down on the dip for a dis-
tance of almost 150 feet.
The body of ore seems, therefore, amply large enough for profitable
exploitation. The operating company has adopted a wise policy in
this respect, the intentions being to push underground working and
accumulate a large supply of stock ore before commencing to build a
treatment plant.
The ore highest in sulphur occurs in the middle 20 feet of the vein,
the ores along each wall running lower in sulphur and higher in cop-
per than the average. Eight carloads of ore were taken from the
tunnel, thus securing a sample entirely across the vein. The average
of the analyses is as follows:
Analysis (average) of Chestatee pyrite.
Per cent.
Sulphur 43.52
Iron '. 39.70
Copper 3.09
Zinc '. .72
Alumina 2. 53
Magnesia . .43
Arsenic ■_ None.
Silica, etc 9.26
Moisture .36
| Analyses from the middle 20 feet would show a higher sulphur and
lower copper content than the average analysis quoted, while analyses
of the portions of the pyrite body near the walls would give lower
t sulphur and higher copper. It is probable that this difference in
a (Composition, which can be noticed even in a hand specimen, will be
)ti taken advantage of in planning the treatment of the ores.
In conclusion it is necessaiy for the writer to acknowledge the aid
received from Mr. N. P. Pratt in this investigation, as the results
obtainable would have been very slight if Mr. Pratt's assistance had
been less freely and courteously given.
NEOCENE RIVERS OF THE SIERRA NEVADA.
By Waldemar Lindgren.
During the geological mapping of the gold belt of the Sierra Nevada
much information was gathered relating to the gravel mines, and
attempts were made to reconstruct the drainage systems of the Neo-
cene rivers, now represented by detached masses of lava-covered
detritus, generally at high elevations above the present drainage
level. Many of these deposits were described in the texts of the
folios of the gold belt by Mr. II. W. Turner or myself. A very brief
review of the gravel mines and the channels of the central gold-
bearing region was given in the bulletin of the Geological Society
of America.^ None of these publications, however, does full justice to
the important and interesting problem of the Neocene stream gravels
of the Sierra Nevada, a subject fascinating alike from the economic
and the scientific side. Whitney's monograph on this same subject,
while containing an enormous amount of valuable observations, is
out of date, because of the careful geological mapping by which the
country has been covered since that volume was written.
It seemed advisable, therefore, to collect in one publication the
principal facts and conclusions regarding the Neocene gravels. Some
supplementary work was found to be necessary, and four months of
the season of 1901 — from the beginning of July to the end of October —
were devoted to the study of the gravels in Butte, Placer, Calaveras,
and Tuolumne counties. In this work I was assisted by Mr. J. M.
Boutwell, who made a special reexamination of the Forest Hill divide
in Placer County. About one month of the summer of 1902 was also
given to a reexamination of certain deposits in the same county.
The data which have been brought together are very voluminous,
and their compilation has necessarily been delayed by the pressure
of other work, but it is hoped will be finished during the present
year. It is intended to review briefly the present state of this min
ing industry, its probable future, its production, and the methods of
mining peculiar to it. The structure of the Sierra Nevada will be
described, and some attention will be devoted to the interesting
a Lindgren, W., Bull. Geol. Soc. Am., Vol. IV, 1893, pp. 257-
64
lindghkn.J NEOCENE EIVERS OF THE SIERRA NEVADA. 65
region of the eastern slope. The gravels and the covering volcanic
material are to he discussed from a geological and petrographical
standpoint; and much space will he given to the question of the con-
nection of the isolated gravel areas with Neocene river systems,
a question which also includes a physiographical description of the
Sierra Nevada during the Neocene period. As a general result the
Neocene Sierra Nevada will be shown to have existed at that time as
a well-defined range, similar to though lower than the present moun-
tains. The rivers headed near the present divide, and flowing in a
general westerly direction, emptied into the bay or marshes of the
Sacramento and San Joaquin valleys. Finally, the probable char-
acter of the orographic disturbance to which the range owes its
present elevation will be discussed.
Bull. 2i:J— 03 5
MINERAL DEPOSITS OF THE BITTERROOT RANGE AND CLEAR-
WATER MOUNTAINS, MONTANA.
By Waldemar Lindgren.
INTRODUCTION.
In L899 a geological reconnaissance was undertaken of the country
between the Bitterroot Valley in Montana on the east and the Lewis-
ton Plateau on the west. During the reconnaissance I was assisted
by Mr. G. W. Stose, of the United States Geological Survey, and Mr.
H. R. Johnson.
The region visited is bordered on the south by the Salmon River
and on the north by the North Fork of the Clearwater. The fertile
Bitterroot Valley lies at the eastern foot of the imposing range of the
Bitterroot. This range, which attains an elevation of 11,000 feet,
westward merges into the great dissected plateau of the Clearwater!
Mountains, which in turn at their western edge descend rather
abruptl}7 to the plateaus of Camas Prairie and Cold Spring Prairie,
forming part of the great Columbia River lava plateau. This latter
plateau has a general elevation of 2,500 to 3,000 feet, and is built up
of horizontal lava flows.
From great glacial cirques in the western slopes of the Bitterroot
Range the Salmon River and the several forks of the Clearwater
River find their way westward in canyons from 3,000 to 5,000 feet deep.
The canyon of the Salmon especially is remarkable for its great length
and depth. In the lower plateau country these rivers flow in more
sharply incised but less deep canyons, which continue to their junc-
tion with the master stream, the Snake River.
The area indicated forms a wild and very sparsely populated moun-
tain region, heavity timbered except on the highest ridges, which
usually show clear evidence of glacial action. The geology is com-
paratively simple. The main Bitterroot Range and the larger part of
the Clearwater Mountains consist of a massive biotite-granite, or,
defining it more correctly, a quartz-monzonite, which is the northward
continuation of the great batholith of the same rock which occupies
so large an area in south-central Idaho. In the latter region this
intrusive mass is of post-Carboniferous and probably late Mesozoic
age, and there is no reason to believe that the granite of the Clear-
water and the Bitterroots is of different age.
66
lindgken] BITTERROOT AND CLEARWATER MOUNTAINS, MONT. 67
Along the whole eastern slope of the Bitterroot Mountains this
granite is made schistose by pressure, and forms a zone a few miles
in width and 60 miles long, following the front of the range. A great
fault accomimnies this schistose zone, dipping, like the schistosity,
about 18° E. Otherwise the granite is generally massive and but
little altered. Several smaller areas of a much older gneiss (pre-
Cambrian?) occur in the Clearwater Mountains, the largest appearing
near Elk City. The granite is intrusive in this gneiss. Along Lolo
Fork at the northern end of the Bitterroot Mountains and near the
head of the Bitterroot River are areas of quartzites and slates (prob-
ably of Cambrian or pre-Cambrian age) into which the granite is also
intrusive. Finally, along the western foot of the Clearwater Moun-
tains, near Harpster and Mount Idaho, occur slates, limestones, and
greenstones, which continue, with a northeasterly strike, up from the
vicinity of the Seven Devils and the Lower Salmon River, and which
are believed to be of Mesozoic age. Into this series, also, the granite
is intrusive.
The main structural features consist of the great Bitterroot fault
and the uplift of the Clearwater Plateau. There is some evidence of
comparatively recent movement along the former, although faulting
is believed to have begun along that line in pre-Miocene times. The
latter uplift is of pre-Miocene age.
ECONOMIC GEOLOGY.
Character of mineral deposits. — The valuable mineral deposits
occurring in the area described in this report consist chiefly of Assure
veins containing gold, together with associated placers derived from
the disintegration of the veins. Deposits containing lead and copper,
and usually silver, occur also in several isolated places. Coal of a
fair quality has also been found in the upper Bitterroot Valley and
in the lower Clearwater drainage. The lead-silver veins of the Coaur
d'Alene Mountains are outside of the limits of this reconnaissance.
Distribution of deposits. — The metalliferous deposits are grouped in
two belts, the first along the western side of the Bitterroot Mountains,
chiefly in Montana; the second along the western foot of the Clear-
water Mountains in Idaho. The deposits of each of these two belts
are again grouped principally in two regions forming the four corners
of the mountain area involved, while the central part of the Clear-
water Mountains appears to be practically barren. The four metal-
liferous areas are distributed as follows: The first occupies the lower
Lolo Fork and the northern end of the Bitterroot Mountains; the
second is found on the headwaters of the South Fork of the Bitterroot
River and reaches over into Idaho, connecting with the mineral belts
at Shoup and Gibbonsville ; the third and most important area includes
Elk City, Buffalo Hump, Dixie, and Florence, as well as numerous
places along the South Fork of the Clearwater River; the fourth area
68 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [hull. 213.
centers in Pierce, but also extends to the headwaters of Lolo Fork
on the south and to the North Fork of the Clearwater on the north.
Character of ore, — The primary deposits are almost exclusively
fissure veins, and with them are associated extensive placers of an
age ranging from Neocene to Recent. In the northern Bitter root
Mountains and on Lolo Fork veins occurring in pre-Cambrian (?)
schists contain chiefly copper, lead, and silver, although some gold is
also found on Lolo Fork. The Curlew mine, at the eastern foot of
the Bitterroot Mountains, contains argentiferous galena, and is located
on a fissure with limestone (pre-Cambrian?) as the foot wall and,
according to accounts. Pleistocene valley gravels as a hanging wall.
The mine is not worked at the present time. On the Upper Bitter-
root River veins cutting porphyry likewise carry chiefly copper and
silver, while argentiferous galena is also known from the Monitor
mine, worked on a vein in gneiss on the divide between the Bitter-
root and Salmon livers. Gold-bearing gravels have been mined for
many years on Hughe Creek. Southward this belt connects with the
gold-bearing deposits at Gibbonsville and Shoup. The rocks at Hughe
Creek and Gibbonsville are pre-Cambrian (?) quartzites and slates.
West of these districts extends a wide granite area which, as far as
known, is barren of mineral deposits. There can be no doubt that
the Clearwater drainage was very thoroughly prospected for placers
during the early days of mining, but outside of the South Fork very
little of value lias been found. In the upper part of the mountains
the glaciation would naturally have swept away any placer deposits
which may have existed, and in this denuded portion it is not impos-
sible thai veins may be found. Nothing of much value lias yet been
encountered. A large vein containing silver is reported to occur on
Rhodes Peak north of the Lolo trail. Along t he Salmon River the
conditions are probably more favorable, and prospecting in the iso-
lated region between Dixie and Shoup might develop something of
value.
As stated before, the western belt contains chiefly gold; only a few
scattered copper deposits are known. The placers of Elk City and
Florence are well known in the history of Idaho and are still worked
to some extent. Veins which furnish the material for these placers
are known to occur in all these localities. The principal mining dis-
tricts are those of Florence, Dixie, Elk City, and Newsome Creek.
The veins, occurring chiefly in gneiss, are almost exclusively of quart!
zose character and contain from 1 to 10 per cent of sulphurets, besides
more or less native gold. The Buffalo Hump district, discovered in
1898, is situated on the high divide between the Clearwater and the
Salmon. It contains many strong quartz veins in granite and slate,
with a varying percentage of free gold and auriferous sulphides.
Active work is in progress there at the present time. The north-
western mineral-bearing area contains placers along Lolo Fork,
ltndgren.J BITTEKROOT AND CLEARWATER MOUNTAINS, MONT. 69
Musselshell Creek, and Oro Fino Creek. Many quartz veins similar
in character to those of the southwestern belt are also worked in
these districts. They are generally incased in schists, more rarely in
granite. Veins of sulphide ores containing gold and copper occur
in amphibolite close to Mount Idaho.
History and production. — The deposits on the eastern slope of the
mountains have not proved of great importance and have chiefly been
discovered and worked at a comparatively recent time. The produc-
tion of all the mines on this side of the mountains probably does not
exceed $1,000,000, of which the larger part has been derived from the
Curlew mine on the north and from the placers of Hughe Creek,
near the head of the Bitterroot River. The important gold belt on
the western slope was discovered about 1860 and was very actively
worked during the following years. Oro Fino or Pierce is reported
to be the earliest discovery in Idaho. It was found in 1860, and dur-
ing that season 25 men wintered there. The gravel near Pierce was
not remarkably rich, but jDaid fairly well in 1861 and 1862.ft In 1874
Pierce produced $70,000. But soon after this the discoveries in Mon-
tana drew most of the miners away from this place and in 1867 but
little mining was going on. Since that time, however, the placers and
quartz mines have been worked each year, although in a somewhat
desultory manner. The total production it is impossible to ascertain,
but probably it has not exceeded a few million dollars.
During late years placer mining has been carried on both in the
low-stream gravels and on the benches. There has also been consid-
erable activity in quartz mining and several small mills have been
built. The output of the placer mines in 1902 is estimated at $30,000,
and that of the quartz veins at the same amount.
Elk City and vicinity proved to be of greater richness. Few quartz
mines have been worked there, practically the whole production being
derived from the placers. In 1863 or 1864 the white miners began
to leave this field, which they considered about worked out, and for
nearly thirty years there were only two or three of them left in the
district, which was almost entirely turned over to the Chinese. In
1892 the white miners began to come back and the Chinese simulta-
neously disappeared, very few of the latter being left now. A certain
amount of placer work is still done in this vicinitj^ each year, chiefly
on bench gravels. The bars of the Clearwater River, which were
worked extensively during the early days, are still occasionally washed.
Regarding the total output of Elk City no satisfactory figures are
available, but not unlike ty the production amounts to about $5,000,000.
After the first few years of abundant production the output fell
rapidly. In 1874 Elk City (including Newsome Creek and Clearwater
station) produced $120,000. From 1882 to 1887 the Elk City district
produced from $35,000 to $73,000 per annum. During recent years
the output has again increased, due to the introduction of dredging
Browne, J. Ross, Report on the Mineral Resources, Washington, 1860.
70 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
and hydraulic operation, and during the last }Tears it has probably
been from $20,000 to $40,000. Very similar were the conditions
during later years in Florence, which Camp has been described in a
previous report." The total output of Florence was, however, consid-
erably larger than that of Elk City.
Florence, Warren, and' Elk City are situated in Idaho County.
According to the Mint reports, this county has, since 1880, produced
an average of $200,000 per annum, or a total of about $6,000,000.
Something like one-half of this amount probably comes from Warren,
leaving $3,000,000 as the production of Florence and Elk City for the
last twenty years. Pierce is located in Shoshone County.
It is a somewhat surprising fact that in spite of the recent activity
in prospecting and working quartz veins the production of Idaho
County should have decreased during the last few years. The Mint
reports give for Idaho County the following amounts:
Precious-metal production of I<l<i/i<> Oounty, Idaho, 1895-1901.
1895 . . $243, 700
1896 . . 155, 350
L897 ---- 230,500
1898 ... 203,500
1899 .. 166,000
1900. ... 152,000
1901.. 161,500
GEOLOGICAL RELATIONS.
Nearly all the vein deposits occur in granite or gneiss, and the pre-
vailing strike of the veins seems to be in an east- west direction. The
granite, which is the prevailing rock, represents the northward con-
tinuation of the greal area of central Idaho north of Snake River.
Gold-bearing veins occur both within this area and along its contacts
with the surrounding, older, sedimentary rocks. But for a long dis-
tance north and south of Salmon River the central large granite areas
seem comparatively barren, contain ng few deposits, with the excep-
tion of the Warren camp.
Within the region here discussed a peculiar relation obtains: The
large central areas of granite, whether sheared, as along the eastern
margin of the Bitterroot Mountains, or massive, as is usually the case,
seem conspicuously barren of deposits. The vein systems appear in
or close to the four smaller areas of sedimentary or metamorphic rocks
which are found at the perip ery of the great central granite area.
This is the case in the quartzitic series of Lolo Fork, in the quartzites,
slates, and gneisses of the upper South Fork of the Bitterroot, and in
the old gneiss areas of Elk City and Pierce. While the age of the
quartz veins is not established beyond doubt, it is probable that they
were formed during the later part of the Mesozoic.
"Lindgren, W., The gold and silver veins of Silver City, De Lamar, and other mining dis-
tricts in Idaho: Twentieth Ann. Rept. U. S. Geol. Survey, Pt. Ill, p. £*1
THE CHISTOCHINA GOLD FIELD, ALASKA:
By Walter C. Mendenhall.
GENERAL DESCRIPTION.
The Chistochina gold field is a small placer area in the northwest-
ern part of the Copper River Basin, Alaska, near the intersection of
the one hundred and forty-fifth meridian west longitude and the
sixty -third parallel north latitude. The district is among the foot-
hills just south of the Alaskan Range, which rises to heights of 8,000
or 9,000 feet in the vicinity, and serves as a gathering ground for ice
fields and glaciers, from which torrential rivers flow north to the
Tanana and south to the Copper. All of the diggings at present are
on two streams, both tributary to Chistochina River, which flows into
the Copper. The larger, but not the more important of these, the
Chesna, is about 12 miles long and empties into the Chistochina
11 miles below its source, in the Chistochina Glacier; the smaller,
Slate Creek, which, with its tributary, Miller Gulch, yields nine-tenths
of the gold of the district, is only -1 or 5 miles long and joins the Chis-
tochina just as the latter emerges from the glacier.
The field is usually entered over the military trail from Valdes, the
nearest seaport, 225 miles to the south, but is accessible from Eagle
City on the Yukon, about 250 miles north. The lack of navigable
streams along these routes means that supplies must be transported
practically the entire distance by pack train or sled, and that there-
fore the district is one of the most remote and difficult of access in
Alaska.
GEOLOGY.
Our present knowledge of the geology of the region ma}7 be briefly
summarized as follows:
That part of the Alaskan Range lying immediately north of the
gold area is made up principally of micaceous schists whose thickness
and age are unknown.
Immediately south of the schists and separated from them by a
fault, whose throw probably exceeds 10,000 feet, is a belt of Permian
a This paper is an abstract from a more complete discussion which is shortly to appear in a
j paper entitled: The Mineral Resources of the Moiint Wrangell District, Alaska.
71
72 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
beds consisting in the upper part of shales and limestones, but includ-
ing, at lower horizons, tuffaceous sediments and flows, which have
an aggregate thickness of 6,000 or 7,000 feet. Many basic igneous
masses occur as dikes or intrusive sheets in these sediments. They
are especially abundant near the fault. The shales are slightly meta-
morphosed in the vicinity of Slate Creek and Miller Gulch, where
some cleavage has developed and a few quartz stringers are found
cutting them. Eocene lignite-bearing beds occur here and there in
small patches infolded with the Permian.
South of the Permian belt occurs a complex terrane of older rocks,
consisting of conglomerates, quartzites, tufaceous beds and probably
flows, which appear to be faulted against the Permian. This terrane
is intruded and altered by dikes and greater masses of granite and
quartz-porphyry. One effect of the intrusion and alteration is a gen-
eral impregnation by pyrite, whose oxidation products color the rocks
rust -red and render them especially conspicuous.
In addition to these easily separable consolidated rock masses,
unconsolidated cla}^s and gravels, either primarily or secondarily of
glacial origin, occur in the vallej^s generally. Near the sources of
the streams these deposits are confined to flood plains or narrow bor-
dering terraces, but downstream the area covered by them widens,
until it merges with the broad drift-filled valley of the upper Copper
Basin, from whose borders isolated bed-rock areas rise as islands.
Besides these Pleistocene deposits in the lowlands, a thin sheet of
cobbles, called by the prospectors the " round wash," is conspicuous
on the hilltops about the head of Slate Creek, Miller Gulch, and some
of the tributaries of the upper Chesna.
GOLD OCCURRENCES.
Practically all of the gold mined at present is taken from Miller
Gulch, Slate Creek, and the Chesna River, whose combined yield for
1 91 >2 is estimated at $225,000. Of this amount, Miller Gulch probably
furnished $175,000, Slate Creek $30,000, and Chesna River $20,000.
Miller Gulch, whose yield is thus seen to be much greater than that
of any other stream in the district, is a steep ravine, less than a mile
long, tributary to Slate Creek. Its bed, decreasing in width from 200
or 300 feet near its mouth to but 4 or 5 feet near its source, is sheeted
over with gravel to a depth of from 4 to 8 feet. This gravel is com-
posed principally of fragments of the somewhat metamorphosed Per-
mian shales in which the ravine is cut, but has an admixture of diabase
and " bird's-eye porphyry " from the intrusives in the shale, and of
cobbles from the "round wash" which occurs over the tops of the
adjacent hills. The gold is rather uniformly distributed across the
gulch, but vertically exhibits the usual concentration near bed rock.
The richness and shallowness of the gravels, and the steep gradient
of the stream, giving abundant fall, have made it easy to win the
mendenhalt,.] CHISTOCHINA GOLD FIELD, ALASKA. 73
gold by simple sluicing methods, and have caused the early develop-
ment of Miller Gulch to a maximum of production, while the poorer
or deeper diggings in the other creeks, wherein some instances expen-
sive plants are required, have been neglected.
The waters of Miller Gulch, discharging into Slate Creek, carry with
them some of the gold from the gulch. As a consequence, for a short
distance below the junction, Slate Creek is rich; indeed, nearly all of
the gold which it has j^ielded has been obtained here. Above Miller
Gulch, on Slate Creek, bed rock is not always within easy reach, in
part because of burial beneath alluvial fans from tributary creeks, in
part because of irregularities attributable to glacial action; and where
bed rock is accessible, the yield is not more than $10 or $15 a day to
the man — about the wage of the district.
The gravels of Slate Creek contain representatives of all the rock
types found in Miller Gulch, and in addition a certain proportion of
material derived from the older quartzites, pyroclastics, and granitic
intrusives occuring on the south side of its lower valley.
On Chesna River the diggings are confined to two localities about 8
miles apart, one near the source, the other near the mouth of the
stream. The greater part of the work on the upper Chesna has been
confined to a small tributary called Ruby Gulch. In the upper part
of this gulch the conditions of accessibility of bed rock and of geo-
logic relations resemble those of Miller Gulch, but the gravels are not
so rich, and the workable ground is not so extensive. The operators,
however, have been able to make satisfactory profits in their work.
Along the lower course of Ruby Gulch the operations have been rather
in the nature of development. Bed rock is not reached, the gravel
being removed by ground sluicing to a clay stratum on whose surface
the gold is found. The yield here is reported to about pay expenses.
The valley of the middle Chesna is clogged by glacial deposits, and
for a number of miles the cursory attempts to find bed rock have not
been successful, but along the lower Chesna, beginning at a point
about H miles above the mouth and extending thence upstream nearly
the same distance, bed rock is within easy reach for short distances
on either side of the river. There is a shallow canyon a few hundred
feet long near the lower end of this stretch, and present operations
are confined to small areas above and below this canyon on the dis-
covery claim of the district.
The Chesna has been tapped a few thousand feet above the canyon
and the water conducted by a ditch along the. south bank of the river
to a point just below the canyon, where a hydraulic plant has been
installed with a head of 1 25 feet.
Although over considerable areas the gravel is but 4 to 8 feet deep,
it was found impracticable to handle it effectively by ordinary sluic-
ing methods, because of the presence of large bowlders and much
water, but those who have installed the hydraulic plant anticipate
74 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [buia.213.
that b}T its use and the construction of drainage ditches the gold can
be easily and profitably secured. As pans are reported to run from
1.7 to 5.5 cents each below the canyon, with a maximum yield of $1
on bed rock, their anticipations seem to be justified.
ORIGIN OF THE GOLD.
The gold from the various streams on which operations are con-
ducted is rather uniform in form, color, and assay value. It gener-
ally occurs in flattened scales or grains, and is but rarely rough and
irregular. It is clean looking and bright yellow in color, and its assay
values are reported to vary from $18 or $18.50 per ounce on Miller
Gulch and the upper Chesna to $18.72 on the lower Chesna.
One-ounce nuggets are not unusual on Miller Gulch, and one piece
is reported which weighed 4 ounces. On Ruby Gulch the largest nug-
get found is valued at $12.75, but nuggets are very rare on the lower
Chesna, the gold being in the form of thin, flat scales. These varia-
tions in coarseness and in assay value are of the kind which would be
expected if the source of the gold were in the region near the head of
Miller and Ruby gulches, where the gold is coarser and the values are
lower.
Some of the operators of the district, admitting that the gold comes
from the vicinity of upper Slate Creek and Chesna River, maintain,
with much show of reason, that it is derived there from the "round
wash," which is particularly heavy about the head of Miller Gulch
and Slate Creek. It is also present on the divide between Ruby
Gulch and the next stream east, so that the advocates of this theory
are able to prove that each stream at present worked to a profit drains
an area in which the "round wash" is found. They likewise regard
the smooth surface of the gold as evidence that it is waterworn and
has therefore been brought from some extraneous source, as is so
evidently true of the "round wash."
Some facts, however, are distinctly opposed to this hypothesis, and
others admit of as ready explanation on another basis.
A small stream, on which a group of claims known as the "Big
Four " has been staked, heads opposite Miller Gulch and flows down
to the Chistochina Glacier. The heaviest deposit of the "round
wash" known in the region occurs on the slopes drained by this
brook, which seems therefore to be more favorably situated than
Miller Gulch, relative to this deposit as a source of the gold; but the
Big Four claims yield fine gold in moderate amount and are not to be
compared in richness to Miller Gulch. Furthermore, Ruby Gulch
and the creek next east of it seem to be equally favorably situated in
relation to the deposit of the "wash" which occupies the divide
between them, yet one has yielded operators a handsome return and
the other is not profitable.
mendenhalk] CHISTOCHINA GOLD FIELD, ALASKA. 75
It is even more significant that the sources of the gold-bearing
creeks are all within an area whose extent coincides with a region of
local metamorphism in the Permian shales, and that no other meta-
morphosed areas of these beds and no other gold districts within
them are known. Where they have been metamorphosed an incipient
cleavage is developed and the shales carry a few narrow quartz
stringers. It is believed that the flat, smooth character of much of
the gold is sufficiently accounted for by its origin in these shales and
by its purity and consequent softness, which lead to rapid smoothing
and polishing with but little transportation.
It is therefore concluded that the gold originates in these Permian
beds, and that in its genesis it is related to the local metamorphism
which they have suffered. It is evidently post-Permian in age, and
since Eocene beds deposited unconformably upon the Permian are
but little folded and wholly unmetamorphosed, it is probably also
pre-Eocene.
GOLD MINING IN CENTRAL WASHINGTON.
By George Otis Smith.
HISTORY OF THE DISTRICT.
The three principal gold-mining districts of central Washington are
included in the Mount Stuart quadrangle. This area has been sur-
veyed geologically, and the descriptive folio is in preparation. The
Peshastin placers were discovered in I860 and have been worked inter-
mittently ever since. The Swank placers have been worked rather
more steadily since their discovery in 1808. Gold-bearing veins were
fust located in the Peshastin district in 1873, and in the Swank in
1881. The mineral veins of the Negro Creek district constitute a con-
tinual ion of Ihose in the Peshastin district. Swauk Creek is a tribu-
tary of Yakima River, and Peshastin Creek of Wenache River, so
that both disi riots are on the eastern slope of the Cascade Range.
Mining in these districts has been conducted by small owners, and
it is impossible to secure any definite data regarding production.
The output of gold of Kittitas County for the years 1884 to 1895, as
reported by the Director of the Mint, aggregates $764,163. About
$5,000 of silver was reported from that county for the same period.
The Peshastin district is now included in Chelan County, but during
this period was a part of Kittitas County. The years 1892 and 1891
were seasons of maximum production, and the area would have prob-
ably steadily increased its output had it not been for the exodus of
miners to Alaska. In view of the activity in these districts in the
years preceding 1884, as well as the production of the last seven years,
it seems that $2,000,000 would be a conservative estimate of the total
gold production of the districts. In the last five years companies
with larger capital have purchased the claims of the small operators,
and mining operations will now be conducted more economically and
with a probable marked increase in the gold production.
AURIFEROUS GRAVELS.
Swauk district. — The Pleistocene gravels along Swauk Creek and
many of its tributaries are gold bearing. These alluvial gravels form
the terraces, which are especially- prominent and extensive at the junc-
tions of Swauk and Williams creeks and of Boulder and Williams
76
smith.] GOLD MINING IN CENTRAL WASHINGTON. 77
creeks. The gravel deposits are from a few feet to 70 or 80 feet in
thickness, and while red or yellow in color at the surface, the gravel
is blue below. The upper portions of the gravel are also less easily
worked, since induration of the gravel has followed the oxidation of
the cementing material.
While fine gold is found throughout the gravel deposits at some
localities, most of the gold occurs close to bed rock and in channels
other than those occupied by the present streams. Its marked char-
acteristic is coarseness. Pieces several ounces in weight are common,
while a number of nuggets weighing 20 ounces or more have been
found, and one or more nuggets of about 50 ounces have been reported,
the largest nugget of the district having a value of $1,100. These
larger nuggets are usually well rounded, but on the tributary streams
wire and leaf gold is found. The gold is not pure, containing consid-
erable silver, which materially decreases its value.
The bed rock, which belongs to the Swauk formation, of Eocene age,
is usually of a nature to favor the collection of the gold. The
inclined beds of hard shale form natural "riffles," and from the
narrow crevices in the shale the best nuggets are often taken. The
sandstone beds wear smooth, in which case the bed rock is apt to be
barren. The old channels, both of Swauk Creek and of its tributaries,
vary somewhat in position from the present course of the stream, but
only within definite limits. The old valleys and the present valleys
are coincident, but, within the wide terraced valleys of the present,
older channels may be found, now on one side and now on the other.
Thus, on Williams Creek and the lower portion of Boulder Creek, the
old water course has been found to the south of the present channel of
the stream, and is in other cases below the bed of the creek. On
Swauk Creek the deposits worked are above the level of the stream,
being essentially bench workings. Here hydraulic plants have been
employed, but elsewhere the practice has been to drift on bed rock.
While the endeavor is to follow the old channels, it is found that the
" pay streak " can not be traced continuously. Ground that will yield
0 to the cubic yard of gravel handled may lie next to ground that
does not contain more than 50 cents to the cubic yard. In the last
few years the operations in the Swauk Basin have been on a larger
scale. Williams Creek has been dammed and methods have been
devised to handle the tailings and bowlders on the lower courses of
Swauk Creek, where the gradient of the valley is low.
The source of the alluvial gold is readily seen to be the quartz veins
known to occur in the immediate vicinity. These will be discussed
in a following paragraph. The noticeable lack of rounding of much
of the gold shows that it has not be<m transported far, and indeed the
limited area of the Swauk drainage basin precludes any very distant
source for the gold. It is only along the Swauk within a few miles of
Liberty and on Williams Creek and its tributaries that gold has been
78 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
found iD paying quantities, and, as will be noted later, this is approxi-
mately the area in which the gold-quartz veins have been discovered.
From the outcrops of these ledges the gold and quartz have been
detached and washed down into the beds of the streams, where the
heavier metal soon became covered by the rounded bowlders and
pebbles with which the channel became filled. The conditions under
which the gold was washed into the streams probably differed little
from those of to-day, except that the streams were then filling up
their valleys.
Peshastin district. — The gravel deposits in the valley of the Peshas-
tin are less extensive than in the Swauk district. The alluvial filling
of the canyon-like valley of the upper half of Peshastin Creek is not
as deep and does not show the well-marked terraces so prominent in
the Swauk Valley. The gravel appears to be gold bearing through-
out, and the gold is quite uniform in distribution. The largest
nuggets are found on the irregular surface of the pre-Eocene slate
which forms the bed rock. While the largest nuggets found in the
Peshastin placers are less than an ounce in weight, and therefore not
comparable with some of the Swauk gold, the Peshastin gold is fairly
coarse and easily saved. The gold is high grade, being worth about
$18 an ounce.
The principal claims on the creek, below Blewett, are owned by the
Mohawk Mining Company, which is hydraulicking the gravels with
water from the upper Peshastin and from Negro Creek. Work which
has been done on Shaser Creek shows the gravels to be gold bearing,
and here also the gold is high grade. This fact is interesting, since,
while the Shaser Creek drainage basin is almost wholly in the same
formation as that of the Swauk Basin, the gold found in the two
creeks is quite different, the Swauk gold containing a considerable
amount of silver.
GOLD-QUARTZ VEINS.
Peshastin (list rid. — A fewT mines in the vicinity of Blewett have
been producers for about twenty-five years. The many changes of
management and methods of operating these properties, however,
make it impossible at the present time to determine accurate^ the
character of the ore that has been mined, or to estimate even approxi-
mately the product during this period. Much of the ore has been
low grade, and the gold has been extracted by means of arrastres,
stamp mills, and a small cyanide plant, but not always with very suc-
cessful results. The small stamp mill first built in this district was
the first erected in the State of Washington. Another mill, with 20
stamps, has lately been rebuilt under the Warrior General manage-
ment.
The best-known property in the district is the Culver group, com-
prising the Culver, Bobtail, and Humming Bird claims, and now known
smith.] GOLD MINING IN CENTRAL WASHINGTON. 79
as the Warrior General mine. This mine in its geologic relations and
vein conditions is typical of the mines of the district. The country
rock is the altered peridotite or serpentine, probably of Mesozoic age,
which exhibits the usual variations in color and structure. The War-
rior General and the other mines are located in a zone of sheared
serpentine, where the mineral-bearing solutions have found conditions
favorable for ore deposition. This mineral zone has a general east-
west course, and extends from east of Blewett across thePeshastin, up
Culver Gulch, and across to the valley of Negro Creek.
The Warrior General vein has a trend of N. 70° -80° E., and is very
irregular in its width. In the walls the serpentine is often talc-like
in appearance, while the compact white quartz of the vein is some-
times banded with green talcose material. Sulphides are present in
the ore, but are not all prominent. The values are mostly in free
gold, which is fine, although in some of the richer quartz the flakes
may be detected with the unaided eye.
The workings in this mine consist of a number of tunnels driven at
different levels into the north wall of Culver Gulch. These follow the
vein for different distances, the vertical distance between the lowest
tunnel, No. 0, and the highest opening of importance, No. 5, being
about 650 feet, and connections have been made between most of the
levels. The vein is approximately vertical, although it has minor
irregularities. The quartz is 7 to 8 feet in width in some places, but
shows pinches in others. In the upper tunnel, No. 5, the ore appears
to be broken, quartz of the same character as that in the lower tunnels
occurring here much more irregularly, although the richest ore has
been taken from the upper workings. Some very rich ore bodies have
been mined, but they are small and their connections have not been
traced. The most extensive work has been done from the lowest
tunnel, and the latest work here shows that the serpentine, which is
so much broken in many parts of this mineralized belt, is here more
solid, a remarkably well-defined and regular wall having been followed
for over 300 feet.
Other properties in the same zone as the Warrior General are the
Polepick, Peshastin, Fraction, Tiptop, Olden, and Lucky Queen.
These have all produced ore which has been worked in the Blewett
mill.
Siuavk district. — The gold-quartz veins of the Swauk are quite dif-
ferent from those in the vicinity of Blewett. They are in part narrow
fissure veins of quartz with some calcite and talcose material, the wall
x)ck being the sandstone or shale of the Swauk formation, of Eocene
ige, or in some cases a diabase or basalt dike may form one wall.
Quartz stringers running off from the vein are common, and at one
ocality thin bands of quartz follow the bedding planes of the sand-
stone. A peculiar type of vein material is locally termed " bird's-eye "
luartz. This occurs in several mines, and may be described as a
80 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
friction breccia in which the angular fragments of black shale are
inclosed in a matrix of quartz and calcite. The quartz shows radial
crystallization outward from the separated fragments, and often open
spaces remain into whicli the small crystals of quartz project. The
walls of such veins are sometimes sharply defined, but in other cases
many small veins of quartz traverse the shattered wall rock in every
direction, so as to render it difficult to draw the limits of the vein
itself. This transition from the peculiar type of vein into the shat-
tered rock shows the "bird's-eye" quartz to be due to brecciation
along more or less well-defined zones, followed by mineralization.
The "bird's-eye" quartz has its gold content very irregularly dis-
tributed. The values are mostly in free gold, with a small amount of
sulphurets present. The gold occurs in fine grains within the quartz or
next to the included shale fragments, and the approximate value of
the ore may be readily found by panning, while in many cases the gold
may be seen on the surface of the quartz, in the form of incrustations
of leaf or wire gold. In a specimen from the Gold Leaf mine per-
fect octahedral crystals of gold lie upon the ends of the quartz crys-
tals. The silicification sometimes extends into the county rock, and
some values are found there. The gold of the quartz veins, like that
of the gravels, is Light colored and contains a considerable percentage
of silver. In the Little York this silver is reported as amounting to
about 20 per cent.
The quartz veins that have been opened np in the upper basin of
Williams Creek have a general uortheast trend, being thus roughly
parallel with the basalt dikes. In the Cougar the hanging wall of
the vein appears to be a badly decomposed basalt dike, while in the
Gold Leal' one vein is wholly in sandstone and shale and another in a
large diabase dike. The relation of the veins to the dikes is there-
fore not const ant, but it may be noted that the fractures which have
been filled by the vein material are usually approximately parallel to
the fractures in the vicinity which have been filled by the intrusion
of basalt. That there has been more than one period of fracturing,
and that the period of mineralization was not exactly contempora-
neous with the time of igneous intrusion, is shown by the occurrence
of veins cutting the dikes themselves. It is quite probable, however,
that the two processes occurred within the same geologic period and
that the ore-bearing solutions derived their heat, and possibly their
mineral content, from the intrusive and eruptive basalt of the area]
A number of quartz veins on Swauk, Williams, Boulder, and Baker
creeks are being prospected at the present time, and in view of the
richness of the alluvial gold which has been derived from the veins
in this vicinity it would seem that the prospecting is well warranted.
ORE DEPOSITS OF TONOPAH AND NEIGHBORING DISTRICTS,
NEVADA/
By J. E. Spurr.
LOCATION AND DISCOVERY OP" THE DISTRICT.
Tonopah is situated in central Nevada, in a range of low, scattered
volcanic mountains which form the southern continuation of the San
Antonio Range, and which themselves, on the south, pass into the
Ralston Desert. It lies about 60 miles east of Sodaville, on the Car-
son and Colorado Railway, whence it can be reached by stage, and
also about the same distance from Candelaria, on the same railroad,
from which point another stage line runs. It can be reached by a
long carriage drive from Belmont, the county seat of Nye County,
and roads radiate from it to the other important points in the State.
This region has been known for a long time and has not been more
inaccessible to prospectors than other similarly situated districts in
the desert region. A few years ago ore was discovered in the Tona-
pah range of hills, some miles south of the present camp. This
locality was called the Southern Klondike and attracted a considera-
ble number of prospectors. Among others, Mr. James Butler, a resi-
dent of Belmont, on his way from that place to the Southern Klondike
camp, passed over the site of the present Tonapah district. Perceiv-
ing a great deal of white quartz scattered upon the ground, he picked
up some pieces and took them to an assayer in the Southern Klon-
dike; but as they did not look particularly promising they were
thrown aside and not tested. On his return trip, however, Mr. But-
ler picked up some more samples and carried them to Belmont,
where he turned them over to Mr. Oddie, a young lawyer and miner,
offering him a share of the claims if he would pay for the assay. Mr.
J Oddie sent the samples to an assayer and promised him half of his
[share if he would assay them. When the assays came back, as they
[did after some delay, they were found to be astonishingly rich, and
|Mr. Butler and his wife started out from Belmont and located their
iblaims in due form.
It is known from certain monuments composed of piled-up quartz
[fragments that Mr. Butler was not the original discoverer, but who
phis was remains a mystery. The monuments are evidently old.
" A more detailed report on this area is in preparation.
Bull. 213—03 6 81
82 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
Present developments. — The development of the new camp has been
astonishingly quick. The property was offered to and refused by
Western capitalists for a very small sum when the exploration pits
were only down a few feet, the reason for refusal being that the rich
ores were probably only superficial Later on, when the developments
had progressed a little further, the property was acquired at a larger
figure by a Philadelphia company. They adopted the principle of
leasing to develop their mine. The leasers set to work vigorously and
in a short time a number of them had extracted sufficient rich ore to
make fortunes of various sizes. Being satisfied with the prospects
of the mine, the company gave out no more leases, but took the
management into their own hands as soon as possible. From that
time to the present the chief mine, the Mizpah, has been conducted
with a view to developing the resources as a basis for future opera-
tions rather than to extracting ore. A number of fine shafts have
been sunk, and the country has been and is being thoroughly investi-
gated, both by drifts along the principal vein and by crosscuts.
Outside of Mr. Butler's original local ions, which became the property
of the Mizpah Company, and those immediately adjoining, numerous
other locations were soon made, until now it is doubtful if there is a
bit of unclaimed ground within several miles. Soon a number of other
shafts were sunk, although with few or no surface indications. The
Fraction shaft, not far from the Mizpah, passed downward through a
body of cap rock of volcanic nature and found mineral veins contain-
ing large values in some places. Later on, the Mizpah Extension, on
the other side of the Mizpah, encountered veins of the same system
after passing through several hundred feet of cap rock. This has
encouraged other companies to sink shafts through the capping, and
many of them are down several hundred feet. Among these may be
mentioned the Ohio Tonopah, the California Tonopah, the Montana
Tonopah, the New York Tonopah, the Tonopah City, and the MacNa-
mara. Work is being pushed vigorously, and before long much of the
underground composition of the district will be shown up.
TOPOGRAPHY.
The topography around Tonopah is not one of great relief. A series
of low and small, detached, and irregular mountains surrounds the
town. The mountains are of volcanic origin, but have been worn
down by erosion so that they have rugged and characteristic erosion
features. The town itself lies in a shallow valley or wash, and from
here a long, gentle wash-slope comes down to a nearly level desert
valley both on the east and on the west.
GENERAL GEOLOGY.
A few miles north of Tonopah ancient limestones, probably Cam-
brian or Silurian, outcrop, and similar limestones are found some
miles to the south, in the southern Klondike district. In the imme-
spurr.] ORE DEPOSITS OF TONOPAH AND VICINITY, NEVADA. 83
diate vicinity of Tonopah, however, only volcanic rocks are found.
These consist of flows, breccias, and derived tuff and ash accumula-
tions. These volcanics are probably of Tertiary age, and represent a
number of successive flows, with intervening showers of ash and
breccia, and erosion intervals. On account of the confusion of these
volcanics the relative order of eruption has not yet been certainly
made out, but at the present time the sequence is considered to be
somewhat as follows :
1. Earlier andesite (latite?).
2. Earlier rhyolite and breccias.
3. Later andesite.
4. Erosion interval.
5. Volcanic breccias and flows.
6. Great water-laid tuff formation containing infusorial silica.
7. Later rhyolite.
8. Latest lava flow (tlacite?).
The oldest volcanic rock is the earlier andesite, which is commonly
called the lode porphyry. Although originally an andesite, it is now,
so far as examined, everywhere almost entirely decomposed and trans-
formed into secondary products, consisting of fibrous muscovite,
secondary quartz, pyrite, chlorite, iron carbonate, etc. In its present
decomposed form, therefore, it is not an andesite, although originally
one. Some forms of the altered rock are what has been described by
early writers in this region as propylite; but Dr. G. F. Becker showed
that the propylite of the Comstock region was an altered andesite,
just as it is at Tonopah. The Tonopah rock and the Comstock rock
are, as a matter of fact, apparently similar in composition, and prob-
ably are also in point of age.
The important veins of the district occur only in this earlier andes-
ite or lode porphyry, and not, so far as yet found, in the later rocks.
So it seems that the mineralization must have followed the first
andesitic eruption. Therefore it is that the overlying volcanics do
mot show these veins, and constitute cap rocks which overlie them,
and which must be pierced in order to reach the lode porphyry and
its associated ores.
The ores are in the form of quartz veins of the kind which have
been described by some writers as the noble quartz formation — that
lis to say, the quartz constitutes almost the whole of the ore, and the
valuable metals are very finely distributed, so as to appear barely or
jnot at all to the naked eye. There is also a very small quantity of
the less valuable metallic minerals. Silver is found in the form of
chloride, sulphide (argentite), and ruby silver. Gold has been seen
fin a free state in the ore.
The deposits are well-defined veins, maintaining a nearly regular
strike and dip. The principal veins average a few feet in width.
,rhe chief trend of the veins is east and west, but in the developed
Region the different veins diverge regularly from one another, so that
84 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
they lie like the spokes of a wheel. Where they come together near
the center from which they radiate, they join and fork in the manner
of linked veins. There is evidence to show that these veins, although
having the characteristics of true fissure veins, have formed along
zones of fracturing or sheeting in the lode porphyry, and have replaced
the porphyry in these zones to a more or less perfect extent. There-
fore, in passing along the veins, at some places they are found to
consist of pure quartz, in other places chiefly of highly silicified
porphyry.
Probably contemporaneous with the mineralization has been the
extreme alteration of the original hornblende-andesite. This altera-
tion, together with the subsequent weathering, has produced a great
variety of appearance in the originally nearly uniform rock. Pyrite
and iron carbonate have been derived from the decomposition of
the dark minerals (mica, hornblende, and pyroxene) of the original
andesite. The decomposition of the feldspars and other minerals has
furnished an abundance of secondary quartz. In some of the most
decomposed and altered phases, therefore, the appearance is that
of a highly siliceous, nearly fresh rock, apparently a rhyolite. This
is one of the common phases in the vicinity of the Mizpah. Other
phases are soft and light colored; others comparatively firm and dark
colored, with abundant pyrite.
The mass of Oddie Mountain is made up of a true rhyolite, later in
point of age than the lode porphyry and containing, so far as yet
known, no veins belonging to this period. It is also somewhat decom-
posed, but not nearly to so great an extent as the lode porphyry.
The later andesite occurs on Mizpah Hill in the same localities as
the earlier andesite, and between certain phases of the two rocks it is
often difficult to distinguish. Originally they both had nearly the
same composition, and they have often been altered in nearly the same
way. The large feldspar crystals of the later andesite, however, are
generalty of greater size and more thickly set together than in the
earlier andesite or lode porphyry. The mica or biotite crystals of the
later andesite are also frequently intact and can be recognized in the
hand specimen, while the micas of the older andesite have generally
completely disappeared. The later andesite is also apt to be more
highly colored in its present state than the earlier rock. It has often
assumed various shades of purple and green, which led the writer to
give it the field name of "purple porphyry." This later andesite is
found in dike form, cutting the earlier eruptives, and also occurs in
the form of extensive flows. It was possibl}7 accompanied by breccias.
About this time, and perhaps succeeding the later andesite, came the
formation of the great series of stratified white volcanic tuffs which I
is exposed around Tonapah. At one point a thickness of several
hundred feet is shown. The perfect stratification indicates that this I
formation was laid down in a lake which must have been of consider-
spurr.] ORE DEPOSITS OF TONOPAH AND VICINITY, NEVADA. 85
able depth. Part of the formation is made up entirely of myriads of
the microscopic siliceous shells of infusoria. Since the lake epoch,
however, erosion has been considerable, leaving the tuff forming some
of the low mountains in the vicinity.
There was apparently a later flow of rhyolite, in general compo-
sition like the earlier flow, but distinct in point of age and now
consequently fresher in appearance. Some mineralization followed
this flow, producing veins and coatings of chalcedony, iron car-
bonate, iron oxide, etc., along the contact and in crevices in the
adjoining rocks. These veins also carry small amounts of gold and
silver, but have no connection with the earlier, more important min-
eralization.
Latest of all was the eruption of lava which forms most of the
mountains around Tonopah. The nature of this lava is dacitic.a
The writer spent two months in the autumn of 1902 making a pre-
liminary investigation of the Tonapah mining district. Mr. W. J.
Peters, of the topographic branch of the Survey, has just finished
making a careful map of that portion of the district which is of great-
est economic importance. This map is on a scale of 800 feet to the
inch. The writer will continue and finish his investigation in the
spring of 1903; will map the different geologic formations, and will
prepare a report showing the relation of the ore deposits to the
different rocks.
There are several perplexing problems which are to be worked out
in the district. One of the most important is the location, as nearly
as possible, of the underground course of the upper contact of the
earlier andesite or lode porphyry, so that mining men may know
approximately where to sink their shafts with the chances of reaching
the porphyry soonest. Another difficult problem will be to ascertain,
if possible, the probable course and extension of the vein systems of
the district. A third problem, perhaps the most important of all, is
the study of the distribution of the rich ores within these veins.
These questions will be dealt with in the forthcoming report.
ORE DEPOSITS IN VICINITY OF TONOPAH.
The writer made a number of brief examinations of certain ore
deposits in the vicinity of Tonopah.
Silver Peak district. — A slight examination was made of the prin-
cipal mine in the Silver Peak district. This mine is on quartz veins
of great thickness and surface extent, which hold relatively small
quantities of gold. The veins have been worked near the surface for
many j^ears past, although lately activity has not been very great. It
is claimed that three-quarters of a million dollars' worth of ore has
already been extracted. There are two parallel veins lying close to
« Dacite is quartz -hearing andesite.
86 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
one another, both of unusual size. The work which has been done
lately is purely in the nature of development, and consists in running
a tunnel to tap the vein at a lower level than has been reached in the
workings from the surface. This tunnel has reached and explored
the vein for some distance, and it is claimed that careful assays show
that the values are as good there as nearer the surface. Taken in con-
nection with the vast quantity of ore, these values are sufficient to
make the mine a great low-grade proposition, provided that power,
water, etc., can be procured with sufficient cheapness to leave a
margin of profit. There is, of course, a scarcity of water in the Sil-
ver Peak region, but hot springs occur in the valley below Silver
Peak, and electrical transmission of power from the streams of the
neighboring White Mountain Range or from the Sierras is one of the
possibilities.
The veins lie in close connection with a mass of granite which is
apparently intrusive into the ancient limestones, and it is believed
that the vein has a close genetic relation to this granite. This point
will be investigated more thoroughly the coining summer, and is an
important one, inasmuch as it bears strongly upon the question of the
persistence of the vein and its values in depth.
Southern Klondike district. — This district has alread}rbeen referred
to as lying '.» or 10 miles south of Tonopah. Its geology in general
and its ore deposits are of an entirely distinct class from those at the
first-mentioned camp. Topographically the country is much the same
as at Tonopah, there being a number of low irregular mountains
which do not rise greatly above the level of the desert vallej^s on each
side. The district is surrounded by volcanic rocks, chiefly rhyolites,
and these rhyolites occupy a portion of the district itself. The rest
of the district is occupied chiefly by Paleozoic limestones, probably
Cambrian or Silurian.
There are two divisions of the Klondike camp — Klondike proper and
East Klondike. In the former, which is the older camp, there is a
long dike-like intrusion, in the limestone, of a siliceous granitic rock, of
which some specimens examined seem to consist chiefly of quartz and
muscovite, and are evidently closely related to similar rock described
some years ago from Belmont, Nev., by the writer, and shown to be
the same as the beresite of the Ural Mountains in Russia. The Bel-
mont district lies nearly due north of Tonopah and Klondike. Close
to the contact of this granitic mass with the limestone, and following
the contact closely for a mile or more, is a quartz vein which at the
surface carried scattered high values of silver and gold. The values
were chiefly in silver chloride. Some parts of the vein contain galena,
which is segregated in bunches. At the very contact of the granite
or beresite with the limestone there is in i>laees a deposit of hard,
nearly black hematite, which is seen to have been derived from the
oxidation of original pyrite, which accompanied the contact in the
spurr.] ORE DEPOSITS OF TONOPAH AND VICINITY, NEVADA. 87
granite, and probably also in the limestone. Deeper exploration of
these deposits has shown them to be almost entirely barren. In the
main vein the quartz has continued in full strength downward, but
the values have become insignificant. Similarly, a tunnel driven to
the contact of granite and limestone, beneath the iron-ore deposits
of the surface, shows nothing. These facts indicate that wre have
here an excellent example of the concentration of values near the
surface, in the extreme upper part of the zone of oxidation, by the
same surface waters that have operated to wear away the district and
produce its topographic relief.
At East Klondike the same limestone is cut into and surrounded
by rhyolite, which has produced almost exactly the same contact phe-
nomena as the granite at the Southern Klondike. Indeed, the two
rocks are probably closely connected in point of composition and ori-
gin. At East Klondike the contact of the rhyolite is marked by a
broad belt of jasperoid, and similar belts are found farther away in
the limestone, along lines of original easy circulation for waters. The
chief vein near this contact consists largely of white quartz, but is
evidently due to the same solutions which produced the dark-blue
jasperoid. The vein and the metallic contents are exactly like the
vein at Klondike. In some places high values have been taken out
of the vein, but exploration has not been pushed far enough to show
the character of the vein in depth. Along certain fracture systems,
which are later than the vein and have broken and displaced it to
some extent, there seems to be a segregation of higher values, accom-
plished probably by more recent circulating surface waters.
Gold Mountain district. — This lies nearty half way between Tonopah
and Klondike and is in the stage of development. Gold Mountain is
composed of rhyolite, both in solid flows and in consolidated tuffs and
breccias. Through these rhyolites run strong and persistent veins of
quartz and delicately colored chalcedony veins, sometimes containing
pyrite. In some parts of some of these veins, especially in the oxi-
dized portions, rich assays have been obtained. The mineralization is
probably of a later date than that which has produced the ores at
Tonopah, but may be of the same age as those at Klondike, although
the ore deposits themselves are of a different character.
Hennepah district. — The Hennepah district was at the time of the
writer's visit very young and so little developed that not much could
be seen. It lies nearly east of Tonopah, on the other side of a broad
desert valley. The rocks of the district are volcanic, bearing a gen-
eral resemblance to those at Tonopah. The veins also, of which two
or three were observed, are of the same general character as the Tono-
pah veins, although so far they have not been shown to have anything
like the strength of the better class of veins in the older camp.
GOLD MINES OF THE MARYSVILLE DISTRICT, MONTANA.
By Walter Harvey Weed.
The Marysville mining district is the most important producer of
the precious metals in the State of Montana, one mine alone having
yielded a total of nearly 115,000,000, while the aggregate production
of the mines of the district has been roughly estimated at double that
figure. The district is located 18 miles northwest of Helena, and is
reached by a branch railroad running north from the main line of the
Northern Pacific Railway. The Great Northern Railway runs a few
miles east of the district. The district comprises a mountainous
country traversed by the continental divide, a few of the mines being
on the western or Pacific slope. The development of the region began
in the early seventies, the rich placer diggings of Silver Creek leading
to the discovery of the ledges which have made the region famous.
Although within its area there have been many productive mines, as
a rule the values have been in rich ore shoots, and after these were
exhausted the property has been abandoned. The most famous prop-
erty of the district is undoubtedly the Drumlummon mine, which has
yielded a larger amount of gold than any other mine in the State. A
later discovery, the Bald Butte mine, has been steadily worked for
many years, one year's dividends approximating the total amount of
capitalization. At the present time the Bald Butte is the only mine
actively worked, and the district therefore may be said to be in
decline.
Geologic features. — The Marysville district consists of a central
mass of granitic rock surrounded hy slaty shales and thin-bedded
argillaceous sandstones. The granitic rock is probably part of the
great granite area which underlies so much of the western portion of.
Montana. The rock is technically a quartz-diorite of even and coarse
grain, showing little variation in appearance or mineralogic develop-
ment. The shaly rocks into which this diorite has been intruded
belong to the Belt terrane and consist of a thickness of many thou-
sand feet of thin-bedded argillaceous rocks. Near the granite con-
tact these rocks are altered to hard and dense hornstones, while
farther away they show a slaty fracture, the laminae corresponding,
however, to the bedding planes. Outside of the district proper, to
the south and west, the Cambrian and later sedimentary rocks
appear. There are a few dikes of acidic porphyry and of dark trap
rocks which cut the granite near its borders and penetrate the sedi-
mentary rocks. These are especially abundant near Bald Butte.
88
weed] GOLD MINES OF MARYSVILLE DISTRICT, MONTANA. 89
The veins. — The geologic map which was rjrepared in the summer of
1901 shows that the veins occur either in close proximity to the granite
contact or adjacent to the intrusive dikes. The vein systems devel-
oped near the town of Marysville show three distinct directions. The
northeastr-system, exemplified in the North Star vein, cuts through the
sedimentary rocks and into the granite. The northwest system is
prominent in the granite area, but has not produced any large ore
bodies. The north-south system is the one to which the Drumlum-
mon lode belongs, and at the Drumlummon mine is parallel to the
granite contact. The ores occur in fissure veins, showing a distinct
quartz filling, either as a solid mass or enveloping angular fragments
of the country rock. The Drumlummon vein is the best known and
may be taken as a type. It is a fault plane with white opaque quartz
inclosing angular fragments of black, green, and drab slates, which
are sometimes distinct and unaltered and at others have been much
decomposed. Where the ore bodies are found the replacement has
been complete and the former presence of the fragments is only recog-
nizable by the outlines of the banded quartz. The vein has distinct-
walls, which are rather wavy and vary from 2 to 20 feet apart. South-
ward the Drumlummon vein itself splits into several branches. It
has been developed for a distance of about 3,000 feet horizontally and
to a depth of 1,600 feet, but no ore was found below the 1,000-foot
level. This vein, which is the largest and the most productive in
the district, consists in its lower levels of a mass of angular rub-
bish, derived from the walls of the fissure, and in places cemented by
quartz, in other places still retaining its original character. Com-
pared with the Empire and other veins, it is much more extensive,
both laterally and vertically, and the values have gone deeper. In
general it may be said that all the veins of the district carry rich
ores in bonanzas and ore shoots within the first 200 feet from the
surface, but that in depth the ores rapidly decrease in value until
the vein is no longer workable. It may also be said that the ore
shoots were well defined, and the intervening vein matter barren
and unworkable. The pitch of the ore shoots conforms to the usual
habit, dipping to the right when looking down the dip of the vein.
The ores consist of sulphides and sulphantimonides of silver, with
gold aggregating 60 per cent of the total value. In the upper levels
the ore is somewhat oxidized, and in the ore shoots of the Drumlum-
mon mine carried extremety high values. In the Bald Butte mine
the larger veins are clear instances of filled fissures with but little
evidence of replacement, and the new vein recently opened contains
a streak a few inches wide of soft ore whose value is extremely high.
Recent attempts have been made to open up some of the large prop-
erties which have been idle for many years. The Empire mine, par-
ticularly, has been opened and new development work begun. There
seems reason to believe that with the low rates of treatment now
available many of these properties may be reopened and worked.
GEOLOGICAL SURVEY PUBLICATIONS ON GOLD AND SILVER.
The following list includes the more important publications by the
United States Geological Survey on precious metals and mining dis-
tricts. Certain mining camps, while principally copper producers,
also produce smaller amounts of gold and silver. Publications on
such districts will be found in the bibliography for copper, on page
186. For a list of the geologic folios in which gold and silver
deposits are mapped and described, reference should be made to the
table on pages 11 to 13 of the present bulletin:
Becker, G. F. Geology of the Comstock lode and the Washoe district; with
atlas. Monograph III. 422 pp. 1882.
Gold fields of the southern Appalachians. In Sixteenth Ann. Rept.,
Pt. Ill, pp. 251-331. 189.-).
- Witwatersrand banket, with notes on other gold-bearing pudding
stones. In Eighteenth Ann. Rept., Pt. V, pp. 153-184. 1897.
Reconnaissance of the gold fields of southern Alaska, with some notes
on the general geology. In Eighteenth Ann. Rept., Pt. III. pp. 1-86. maps. 1897.
Brief memorandum on the geology of the Philippine Islands. In Twen-
tieth Ann. Rept., Pt. II, pp. 3-7. 1900.
Brooks, A. H. Reconnaissance in the Tanana and White river basins, Alaska,
in 1898. In Twentieth Ann. Rept., Pt. VII, pp. 429-494. 1900.
Reconnaissance from Pyramid Harbor to Eagle City, Alaska. In
Twenty-first Ann. Rept., Pt. II, pp. 331-391. 1901.
Preliminary report on the Ketchikan mining district, Alaska. Profes-
sional Paper No. 1 . 120 pp. 1902.
Brooks, A. H., Richardson, G. B.. and Collier, A. J. Reconnaissance of the
Cape Nome and adjacent gold fields of Seward Peninsula, Alaska, in 1900. In
reconnaissances in the Cape Nome and Norton Bay regions, Alaska, in 1900; a
royal octavo pamphlet published in 1901 by order of Congress, pp. 1-184.
Collier, A. J. A reconnaissance of the northwestern portion of Seward Penin-
sula. Alaska. Professional Paper No. 2. 68 pp. 1902.
Cross, Whitman. General geology of the Cripple Creek district, Colorado. In
Sixteenth Ann. Rept., Pt. II, pp. 13-109. 1895.
— Geology of Silver Cliff and the Rosita Hills, Colorado. In Seventeenth
Ann. Rept., Pt, II, pp. 209-403. 1896.
Cross, Whitman, and Spencer, A. C. Geology of the Rico Mountains, Colo-
rado. In Twenty-first Ann. Rept., Pt. II., pp. 15-165. 1900.
Curtis, J. S. Silver-lead deposits of Eureka, Nevada. Monograph VII. 200
pp. 1884.
Diller, J. S. The Bohemia mining region of western Oregon, with notes on
the Blue River mining region. In Twentieth Ann. Rept., Pt. Ill, pp. 7-36. 1900.
Eldridge, G. H. Reconnaissance in the Sushitna Basin and adjacent territory
in Alaska in 1898. In Twentieth Ann. Rept., Pt. VII, pp. 1-29. 1900.
Emmons, S. F. Geology and mining industry of Leadville, Colorado; with
atlas. Monograph XII. 870 pp. 1886.
Progress of the precious metal industry in the United States since 1880.
In Mineral Resources U. S. for 1891, pp. 46-94. 1892.
Economic geology of the Mercur mining district, Utah. In Sixteenth
Ann. Rept., Pt. II, pp. 349-369. 1895.
The mines of Custer County, Colorado. In Seventeenth Ann. Rept.,
Pt. II, pp. 411-472. 1896.
•id
PUBLICATIONS ON GOLD AND SILVER. 91
Hague, Arnold. Geology of the Eureka district, Nevada. Monograph XX.
419 pp. 1892.
Hahn. O. H. The smelting of argentiferous lead ores in the far West. In
Mineral Resources U. S. for 1882, pp. 324-345. 1883.
Lindgren, Waldemar. The gold-silver mines of Ophir, California. In Four-
teenth Ann. Rept.. Pt. II, pp. 243-284. 1894.
The gold-quartz veins of Nevada City and Grass Valley districts. Cali-
fornia. In Seventeenth Ann. Rept., Pt. II, pp. 1-262. 1896.
The mining districts of the Idaho Basin and the Boise Ridge. Idaho.
In Eighteenth Ann. Rept., Pt. Ill, pp. 625-736. 1898.
The gold and silver veins of Silver City, De Lamar, and other mining
districts in Idaho. In Twentieth Ann. Rept., Pt. Ill, pp. 75-256. 1900.
The gold belt of the Blue Mountains of Oregon. In Twenty-second
Ann. Rept., Pt. II. pp. 551-776. 1902.
Lord, E. Comstock mining and miners. Monograph IV. 451 pp. 1883.
Mendenhall, W. C. Reconnaissance in the Norton Bay region, Alaska, in
1900. In reconnaissances in the Cape Nome and Norton Bay regions, Alaska, in
1900; a royal octavo pamphlet published in 1901 by order of Congress, pp. 181-218
Reconnaissance from Resurrection Bay to the Tanana River in 1898.
In Twentieth Ann. Rept., Pt. VII, pp. 264-340. 1900.
Nitze, H. B. C. History of gold mining and metallurgy in the Southern States.
In Twentieth Ann. Rept., Pt. VI, pp. 111-123. 1899.
Penrose, R. A. F., jr. Mining geology of the Cripple Creek district, Colo-
rado. In Sixteenth Ann. Rept., Pt. II, pp. 111-209. 1895.
Purington, C. W. Preliminary report on the mining industries of the Tellu-
ride quadrangle. Colorado. In Eighteenth Ann. Rept., Pt. Ill, pp. 745-850. 1898.
Ransome, F. L. Report on the economic geology of the Silverton quadrangle,
Colorado. Bulletin No. 182. 265 pp. 1901.
The ore deposits of the Rico Mountains, Colorado. In Twenty-second
Ann. Rept., Pt. II, pp, 229-398. 1902.
Schrader, F. C. Preliminary report of a reconnaissance along Chandler and
Koyukuk rivers, Alaska, in 1899. In Twenty-first Ann. Rept., Pt. II, pp. 447-
485. 1900.
Spurr, J. E. Economic geology of the Mercur mining district, Utah. In Six-
teenth Ann. Rept., Pt. II, pp. 343-455. 1895.
— — Geology of the Aspen mining district, Colorado; with atlas. Mono,
graph XXXI. 260 pp. 1898.
The ore deposits of Monte Cristo, Washington. In Twenty-second
Ann. Rept., Pt. II, pp. 777-866. 1902.
Spurr, J. E., and Goodrich, H. B. Geology of the Yukon gold district,
Alaska, with an introductory chapter on the history and conditions of the district
to 1887. In Eighteenth Ann. Rept., Pt. Ill, pp. 89-392, maps. 1898.
Tower, G. W., and Smith, G. O. Geology and mining industry of the Tintic
district, Utah. In Nineteenth Ann. Rept. , Pt. Ill, pp. 601-767. 1899.
Weed, W. H. Geology of the Little Belt Mountains, Montana, with notes on
the mineral deposits of the Neihart, Barker, Yogo,and other districts. In Twen-
tieth Ann. Rept.. Pt. III. pp. 271-461. 1900.
Weed, W. H., and Barrell, J. Geology and ore deposits of the Elkhorn min-
ing district, Jefferson County, Montana. In Twenty-second Ann. Rept., Pt. II,
pp. 399-550. 1902.
Weed, W. H., and Pirsson, L. V. Geology of the Castle Mountain mining dis-
trict, Montana. Bulletin No. 139. 164 pp. 1896. •
Geology and mining resources of the Judith Mountains of Mon-
tana. In Eighteenth Ann. Rept., Pt. Ill, pp. 446-616. 1898.
Williams, A. Popular fallacies regarding precious metal ore deposits. In
Fourth Ann. Rept., pp. 253-271. 1884.
QUICKSILVER, PLATINUM, TIN. TUNGSTEN, CHROMIUM,
AND NICKEL.
Of the metals here grouped only two — quicksilver and chromium —
are at present worked on a large scale in the United States. The
papers on tin and tungsten presented below are reprints, in slightly
condensed form, of reports which have recently appeared in Survey
publications. A description of the Rambler copper mine, in Wyoming,
is included, as platinum has recently been discovered in the ores of
this mine.
STREAM TIN IN ALASKA.
By Alfred H. Brooks.
White studying the gold placers at York, on the Seward Peninsula.
Alaska, the writer's attention was called to the occurrence of stream
tin (cassiterite) in the placers. The stream tin was found at two
localities in the region. The first is on Buhner Creek, a westerly
tributary of the Anikovik River. The mouth of Buhner Creek is
about 3 miles from Bering Sea. The occurrence is best located by
stating that it lies about 10 miles east of Cape Prince of Wales, and
very near the northwestern extremity of the continent. On Buhner
Creek 2 to 3 feet of gravel overlies the bed rock, which consists of
arenaceous schists, often graphitic, together with some graphitic
slates. The bed rock is much jointed, the schists being broken up
into pencil- shaped fragments. They strike nearly at right angles to
the course of the stream and offer natural riffles for the concentration
of heavier material. A hasty reconnaissance of the drainage basin
of this stream, which includes not more than a square mile of area,
showed the same series of rocks throughout its extent. At a few
localities some deeply weathered, dark-green intrusives were found,
probably of a diabasic character. The slates and schists are every-
where penetrated by small veins, consisting usualty of quartz with
some calcite, and frequently carrying pyrite and sometimes gold.
These veins are very irregular, often widening out to form blebs, and
again contracting so as not to be easily traceable.
92
bkooks] STREAM TIN IN ALASKA. 93
The stream tin is concentrated on the bed rock with other heavy
minerals, and was found by the miners in the sluice boxes. A sample
of the concentrate in one of the sluice boxes was examined by Mr.
Arthur J. Collier, and yielded the following minerals: Cassiterite,
magnetite, ilmenite, limonite, pyrite, fluorite, garnets, and gold.
The determination of percentage by weight was as follows: 90 per
cent tin-stone; 5 per cent magnetite; other minerals, 5 per cent. The
cassiterite occurs in grains and pebbles, from those microscopic in
size to those half an inch in diameter; they have subrounded and
rounded forms. In some cases there is a suggestion of pyramidal and
prismatic crystal forms. The cassiterite varies in color from a light
brown to a lustrous black.
A second locality of this mineral was found on the Anikovik
River about half a mile below the mouth of Buhner Creek. Here the
cassiterite was also found with the concentrates from the mining
operations. One pebble of stream tin obtained from this locality was
about 2 inches in diameter.
It will be necessary to make a more detailed examination of this
region to determine where this mineral occurs in the bed rock. The
facts obtained by the writer point toward the conclusion that its
source was in the quartz and calcite veins in which the gold was found.
No cassiterite was, however, found in this vein material.
No evidence was found that this cassiterite is in any way connected
with granitic intrusions, which is its usual association in other regions.
As far as known there are no intrusives of such rocks within the
drainage basins of streams where the tin was found. The nearest
known granitic rock is the biotite-granite stock which forms the
promontory of Cape Prince of Wales and which is at least 10 miles
distant.
This discovery of stream tin has, at present, scientific rather than
commercial interest. No developments have been made which would
warrant the conclusion that valuable tin deposits exist in the York
district. It is worth while, however, for the prospectors who visit
this region to familiarize themselves with the physical properties of
the mineral, so as to be able to recognize it if found. By this means
deposits carrying values may be discovered, and the cassiterite will
probably be traced to its source in the bed rock.
PLATINUM IN COPPER ORES IN WYOMING.
By S. F. Emmons.
INTRODUCTION.
The occurrence of platinum in the form of sperrylite (arsenide of
platinum), associated with copper ores in the Sudbury district of
Canada, has been known since 1889. a It has since been discovered
by Hidden6 in North Carolina. In the past winter the occurrence of
platinum in the ore of the New Rambler mine of Wyoming was
announced by Prof . Wilbur C. Knight/ and upon examination of the
ore by H. L. Wells and S. L. Penfield/* of Yale University, it was
found to occur in well-defined crystals in association with covellite
and pyrite.
The known occurrences of platinum in definite mineral combination
are so rare as to render this new locality of considerable importance;
hence a brief visit to the mine was made by the writer during the past
summer, after spending some time in camp with Mr. A. C. Spencer,
who Avas engaged in a geological survey of the Encampment group of
mountains, a northern extension of the Park Range of Colorado, lying
on the west side of the North Platte River. The following is a brief
but necessarily incomplete statement of the geological relations of the
deposits as far as they were ascertained :
The mine is situated a little east of south of Medicine Peak, the
highest point of the Medicine Bow Mountains on Beaver Creek, a
little stream tributary to the headwaters of Douglas Creek. It is con-
nected with Laramie City on the Union Pacific Railroad by mail and
stage line, the distance being about 32 miles in a straight line, though
by the windings of the road it is about half as much again. A slightly
shorter but more precipitous road runs westward across the North
Platte Valley to the town of Encampment, where there is a smelter
in which 2,000 to 3,000 tons of ore from the Rambler mine were
smelted during the winter of 1901-2. The little settlement which has
sprung up about the mine is designated by the postal authorities
"Holmes,,, from the name of the manager and principal owner of the
"Am. Jour. Sci., 3d series, Vol. XXXVII, 1889, pp. 67-71.
''Idem, 4th series, Vol. I, 1898, pp. 381, 467.
cEng. and Min. Jour., Dec. 31, 1901, p. 845.
'?Ain. Jour. Sci., Feb., 1902, 4th series, Vol. XIII, p. 95.
94
emmons] PLATINUM IN COPPER ORES IN WYOMING. 95
mine. A railroad is now building from Laramie City westward, which
it is expected will eventually connect with Holmes.
The mine is at present opened by a vertical shaft 200 feet deep, but
at the time of visit, owing to certain changes which were taking place
in machinery and ownership, the lower 100 feet were not accessible;
hence a study of the unaltered ore must be postponed to a later date.
A small matting furnace has been erected near the shaft for treating
second-class ore. The ore shipped away from the mine is said to
aggregate nearly 4,000 tons and to have assaj^ed 25 to -30 per cent cop-
per. According to Professor Knight, it all contained more or less
platinum.
TOPOGRAPHY.
The Medicine Bow Range is topographically a northwestern contin-
uation of the Front Range of Colorado, which, as it enters Wyoming,
spreads out into two forks that inclose the broad valley known as the
Laramie Plains. The eastern boundary of these plains is formed by
the Black Hills of Wyoming, sometimes known as the "Laramie"
Hills — a north-south uplift of older rocks, mainly granite, which ends
at the north bend of the North Platte River, where these rocks dis-
appear under Mesozoic sediments.
The Medicine Bow Range on the west likewise dips down under the
Mesozoic sediments and is lost as a range, its almost isolated northern
point being known as "Elk" Mountain. As seen from the Laramie
Plains a striking feature is the plateau-like structure of the main mass
of the uplift. On its eastern flanks it rises abruptly from the plains
about 2,000 feet; then slopes back almost at a level with an average
elevation of 9,000 to 10,000 feet to the central uplift around Medicine
Peak, which is again about 2,000 feet above the plateau.
This plateau-like portion of the range is, for the most part, covered
with a comparatively abundant forest growth, and its streams run in
shallow swale-like valleys which change rapidly to deep rocky gorges
in their lower courses as they leave the plateau. At Holmes, which
is on the higher part of the plateau, the forest covering is unusually
dense and the rock surface is covered by 0 to 16 feet of wash, so that
rock outcrops are rare and iirospecting has to be done by trenching
and shaft sinking, and the geological relations are correspondingly
difficult to decipher.
GEOLOGY.
In its geological composition and structure the Medicine Bow Range
appears to resemble more closely the Encampment Mountains on the
opposite side of the Platte Valley than the Colorado ranges, and there
is some reason for assuming that the two once formed part of one and
the same mountain uplift, and that their separation by the cutting of
the Platte Valley has been of comparatively recent geological date.
The principal distinction from the other ranges that have a core
96 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
that has generally been assumed to be Archean is the prevalence of
distinctly sedimentary beds, largely quartzites of pre-Cambrian age,
which form the crest of the ridges in either group of hills. Around
the lower flanks of the ranges, on the other hand, and, so far as can
be seen, in the intermediate Platte Valley, the basement rocks are
granite and gneisses like those called Archean in Colorado, a^d the
sedimentary rocks are seldom, if ever, seen.
The sedimentary series in the Encampment Range are quartzites,
with some limestones and conglomerates, penetrated by sheets and
dikes of eruptive rock, mainly diorite, and closely compressed into
folds with an east-west strike, the whole highly metamorphosed.
That the same series of rocks occurs in the Medicine Bow Range is
evident from observation, though the structure could not be made
out with any definite ness in so short a visit, owing to the covering of
forest and wash on the plateau. According to the Fortieth Parallel
reports, Medicine Peak is a mass of white quartzite with a general
synclinal structure. The same rock is said to occur on Douglas
Creek a few miles below the Rambler mine, and quartzites were
observed in considerable masses on the ridge between French and
Mullan creeks a few miles west of that mine. At the Rambler mine
itself and for a considerable distance on either side, as shown by the
dumps of the different prospects, the rock is diorite. That at the
Rambler mine is coarsely granular, with thoroughly granitic struc-
ture and some development of pegmatitic phases, and is thought to
be part of a considerable stock breaking through quartzites and
underlying gneisses.
Microscopical study of two specimens from the bottom of the shaft,
by Mr. Waldemar Lindgren, shows the latter rock to be a hornblende-
biotite-diorite of normal type, its feldspars being labradorite, with
quartz occurring sparingly in grains between the feldspars, and mag-
netite in small contact grains, mostly embedded in hornblende or
biotite. As secondary minerals are found sericite and epidote in the
feldspars, and a little chlorite in places in hornblende and biotite.
Some red hematite occurs in seams, and p37rite in grains and cubical
crystals, generally in the hornblende, and always associated with a
little chlorite.
RAMBLER MINE.
The mine was originally opened by an incline, but after the discov-
ery of the large bodies of ore a vertical two-compartment shaft was
sunk, through which access is now had to the workings. At time of
visit the mine below the 100-foot level was inaccessible. Above this
level and for some little distance below, both ore and country rock
are much altered, and so much transmigration of the former has
taken place that it was quite impossible to determine the original
form and nature of the deposit.
emmons] PLATINUM IN COPPER ORES IN WYOMING. 97
Thus far three large bodies, about 40 to 50 feet iu diameter aud 12
to 30 feet high, have been opened. The upper one immediately below
the wash was a gossan of iron oxide carrying about 9 ounces of silver
per ton, with a trace of gold, from which the copper had been pretty
completely leached out. Below this came silicates and carbonates
of copper. The zone of enriched sulphide below the oxidized body,
which alone was accessible, is apparently larger and certainly richer,
and extends 30 feet or more above the level. It shows two large ore
bodies of no definite outline inclosed in highly decomposed diorite.
The latter, in its extreme form called " talc" by the miners, is a white
kaolinized mass of the consistency of soft clay, but often retaining
something of the original granular structure of the rock. Near the
ore bodies covellite grains are so uniformly distributed through it as
to give the appearance at a little distance of basic silicates in a white
feldspathic rock. The remarkable feature of the ore is the abun-
dance of the rather uncommon indigo-blue copper sulphide, covellite
(CuS). The upper part of the body is slightly stained with iron oxide,
while in the lower part some pyrite is visible, but not in relatively
large proportion. Cuprite occurs here and there in brilliant ver-
milion red crystals, and is sometimes reduced to native copper. The
covellite is rather irregularly distributed through the kaolin-like
mass, but sometimes occurs in massive lenses up to 2 feet thick. In
so plastic a mass no definite structure could be observed in the mine,
but some of the pyritous ore on the dump showed a certain vein-like
structure. A specimen of this, which was examined microscopically
by Mr. Lindgren, shows that the covellite replaces the pyrite directly,
without the formation of intermediate minerals; that the ore has a
cellular structure, apparently resulting from reduction in volume
during its conversion, and that the roughly rounded cavities are
often lined with soft white silica in mammillary crusts, the manner of
occurrence indicating that it was formed by solution, either simulta-
neously with or immediately after the formation of the covellite.
In two places secondary pyrite of later formation than some of the
! covellite was observed.
Sperrylite could not be distinguished in the thin section. From
the description given by Wells and Penfield of that which they were
able to separate, it probably occurred in ore similar in character to
this, and from its fresh appearance it seems probable that the sper-
rylite was an original constituent of the sulphide ore. More definite
knowledge as to its manner of occurrence will probably be obtained
when the deposit has been opened at greater depths and beyond the
reach of surface alteration.
Bull. 213—03 7
TUNGSTEN MINING AT TRUMBULL, CONN.
By W. H. Hobbs.
A deposit of tungsten ore of considerable economic importance is
found at Trumbull, Conn. The ore occurs along the planes of contact
between crystalline limestone and two bodies of hornblende-schist,
the latter being a metamorphosed igneous rock. The tungsten min-
erals (wolframite and scheelite) seem to be concentrated just below
the contact of the limestone with the lower body of hornblende-schist,
while in lateral distribution they are very variable. In 1898 exploita-
tion of this deposit for the tungsten ores was commenced and was car-
ried on until 1901, when operations were temporarily abandoned.
The companies which managed the property carried out somewhat
extensive mining operations, and expended considerable sums for
buildings and machinery.
The method of mining lias been to sink pits at the contact and fol-
low down the tungsten-bearing zone. The larger blocks obtained by
blasting are broken with sledges and the picked ore sent to the mill.
The ore on reaching the mill is sent through a 15 by 21 inch Blake
crusher, with a capacity of 10 tons per hour. This crusher discharges
its product on the upper end of the picking table. An endless rubber
belt acts as carrier and feeds to two small crushers on the floor below.
These crushers deliver their product to two sets of Cornish rolls,
running one-fourth inch apart and having a 22-inch diameter and
16-inch lace From the rolls the material is elevated to the top of the
mill and delivered \ o a pair of revolving wire screens 36 inches in diam-
eter and 8 feet in length. These screens are one-eighth-inch mesh,
and therefore refuse most of the material. A considerable portion of
the dust is here drawn out by a current of air which passes under the
screens. The material refused by the screens is carried by gravity to
a pair of high-speed rolls, of 30-inch diameter and 18-inch face, run-
ning one-eighth inch apart. From them it is returned to the elevator
and again sent to the one-eighth-inch screens. All the material pass-
ing the one-eighth-inch screens at either the first or second trial is
sent to Wolf gyrating screens of three sizes, the mesh being 40, 60,
and 90, respectively.
Concentration is effected by a dry process, the Hooper pneumatic
concentrator being used. This delivers a clean concentrate and leaves
little ore in the tailings. Each machine is capable of treating 10 tons
of material a day, and the yield of tungsten ore is said to be 5 per
cent. The ore carries a little pyrite, which must be removed by
roasting. No attempt is made at the mine to reduce the mineral to
tungstic oxide.
98
TIN DEPOSITS AT EL PASO, TEX.
By W. H. Weed.
The El Paso tin deposits lie on the east flank of the Franklin Moun-
tains, the southern extension of the Oregon or San Andreas Range,
about 10 miles north of El Paso. The ores were discovered in 1899
and have been prospected by several open cuts and pits, the deepest
of which is about 50 feet below the surface. The place is distant
about 14 miles by wagon road from El Paso. The Rock Island Rail-
road crosses the flat 3 or 4 miles east of the property, and the main
line of the Southern Pacific lies 10 miles to the south. There is a
good spring one-fourth of a mile from the ledges, but there is no large
supply of water nearer than the Rio Grande. The mesa is under-
lain by water, the city of El Paso being supplied from driven wells
sunk in the mesa gravels.
GEOLOGICAL STRUCTURE AND FORMATION.
The geological structure is simple and easily made out. The moun-
tain range consists of Cambrian and other Paleozoic limestones,
upturned by and resting upon an intrusive mass of coarse-grained
granite that forms the central core of the range. This granite is well
exposed for a distance of 4 or 5 miles along the eastern side of the
mountains, forming the lower half of the mountains proper, and in
places extending out to the foothills. The crest of the range consists
of steeply tilted, heavily bedded, dark-gray limestones dipping west-
ward. The basal quartzites were observed in the drift seen in arroyos,
so that the granite is probably intruded between the base of the Cam-
brian rocks and the underlying Archean complex.
The eastern foothills consist mainly of limestones, but near the tin
deposits these bedded rocks have been cut through and granite now
forms the surface, remnants of the limestone cover showing as isolated
j masses capping the hillocks. North of the tin mines a transverse
iridge of the range shows the granite to be sheeted by well-marked
planes, dipping eastward at an angle of about 45° to 50°. The granite
is very much altered by surface decomposition, and crumbles readily
to a coarse sand. The granite is sheeted near the veins, the planes
of sheeting being parallel to the veins themselves. The general
sheeting, however, is in a different direction, the average strike being
|N. 20° E., and the dip 70° SE. A thin section of this granite, exam-
99
100 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
ined under the microscope, shows the rock to be a coarse-grained
normal soda granite, with much anhedral quartz and anhedral feld-
spar, largely microperthite, with some few grains of microcline. A
few small flakes of brownish-green hornblende and some small grains
of magnetite were also seen.
White aplite-granite occurs in veinlets and irregular masses intru-
sive in the granite, but none was observed close to the veins.
ORES AND VEINS.
The ores consist of cassiterite, or oxide of tin, with wolframite
(tungstate of iron and manganese) in a gangue of quartz. Specimens
of nearly pure cassiterite weighing several pounds have been found
on the surface, and this mineral occurs in the quartz, either alone or
associated with wolframite. The most abundant ore is a granular
mixture of tin ore and quartz which resembles a coarse granite and
corresponds to the greisen ore of European tin deposits. Pyrite
occurs rarely in the eastern exposures of the vein, but appears to
constitute the bulk of the metallic contents in exposures seen in the
westernmost openings. These ores occur in well-defined veins, which
run up the slopes nearly at right angles to the direction of the range,
the strike being approximately east- west and the veins dipping steeply
to the north. Three veins have been discovered, all of which have
been exposed by open-cut work and by pits for several hundred feet
in length. The most northerly vein is traceable along the surface for
a distance of about 1,200 feet. The middle vein lies about 300 feet
south of the east end of the northern one, but apparently converges
westward toward the northern vein. The southern vein, which is the
smallest of the three, lies about GOO feet farther south.
The veins exhibit the usual characters of the European tin veins,
notably those of Cornwall, England, their clearly defined fissures show-
ing a central core or lead of coarse quartz, sometimes containing tin
ore, and flanked on either side by altered rock in which the tin ore
replaces the feldspar of the granite. Where this metasomatic replace-
ment is complete the ore shows a mixture of cassiterite, with or with-
out wolframite and quartz. Where the replacement is only partial the
greisen ore fades off into the unaltered granite. A cross section of
the veins shows, therefore, the same phenomena seen in Cornwall.
The central mass of quartz corresponds to the " leader" of the Cornish
veins. It is composed of massive, coarsely crystalline quartz, some-
times showing comb structure, and it is clearly the result of the filling
of the open fissure by quartz. The adjacent ore-bearing material is
a replacement deposit in which the mineral solutions have substituted
ore for the feldspar of the granite by metasomatic action; in other
words, the main mass of the ore occurs alongside of a quartz vein, and
is due to the alteration of the granite forming the walls of the fissure.
In general, the ore passes into the granite by insensible transition and
there are no distinct walls.
weed.] TIN DEPOSITS AT EL PASO, TEX. 101
From a thin section of the ore, examined under the microscope, the
rock is seen to be quartz cassiterite. It is a coarsely granular rock
consisting of anhedral quartz, with grains of slightly brownish cassit-
erite intimately intergrown with quartz along the edges. The quartz
is full of fluid inclusions and makes up about 75 per cent of the mass.
One small grain of tourmaline and a few flakes of sericite were seen.
Neither topaz nor mica occurs in the section, and no remains of feld-
spar were observed. If this is a metasomatic form of the granite a
silicification has taken place. The microscope affords no direct evi-
dence, however, that this ore is metasomatic.
The north vein has a course of N. 85|° W. magnetic, as determined
from the openings at the east end. At the west end of the workings
the course observed, looking back along the outcrop, appears to be
N. 80° E. for the northern vein and N. 80° W. for the middle vein;
so that if these observations are correct the veins must intersect toward
the Avest. The surveys by the owners of the property show a course
N. 85|° W. for the middle and 05° W. for the south vein.
DEVELOPMENT.
A shaft 35 feet deep has been sunk on the north vein at the eastern
end of the vein outcrop. This shaft is about 5 by 10 feet across and
shows a very well-defined vein about 5 feet wide, having a dip of
about 70° to the north. The sides of the shaft show excellent ore,
mostly of the greisen variety, extending down for 8 to 15 feet below
the top. At this point a slip crosses the shaft and cuts out the ore.
This slip, or fault, is a clay seam, but one-fourth to one-half inch in
thickness, and seems to have thrown the upper part of the vein to the
north. The lower half of the shaft reveals only rusty granite, shat-
tered and showing films of quartz, but without recognizable ore. A
crosscut south from the bottom of the shaft should reach the vein if
the fault is a normal one. In the exposure seen in the upper part of
the shaft the ore occurs in bunches in altered granite and lies on the
north side of a 15-inch streak of sheeted and rusty quartz. A second
shaft on the north vein has been sunk at a point about 300 feet west
of the one just noted. This shaft is about 25 feet deep. The vein is
well exposed at the top, and shows a dip northward, but the shaft
passes out of the vein into the sheeted granite, forming the foot Avail.
A crosscut about 8 feet in length, driven from the bottom of the shaft,
cuts the vein, but does not pass through it. The sheeting of the
granite seen in this shaft is very pronounced, the rock being divided
into plates from one-fourth inch to 12 inches in thickness by planes
dipping Gl° E. and crossing the vein at 90°. The outcrop of the vein
is traceable westward up the slopes by its rusty quartz, and a nearly
continuous ledge can be followed. This outcrop has been opened at
intervals of a few yards by trenches, Avhich expose the A^ein and show
it to haAre a thickness of from 2 to 6 feet, Avith about half this thickness
102 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
of ore. No samples were, however, taken, and it is uncertain whether
the altered granite does not contain a percentage of tin oxide. The
most westerly working that could be surely identified as being upon
the north vein is a pit 6 feet deep, which shows a 6-foot vein in wh ich
the quartz is bluish in color and the tin ore is associated with much
pyrite. This point is about 600 or more feet west of the first shaft;
West of this point the ledge can not be traced across the slopes, but
tin ore is seen on the slope 100 feet higher, and still farther north a
good vein shows, carrying much pyrite, but devoid of any recogniz-
able tin ore.
The middle vein is developed by a shaft 50 feet deep, which shows
a vein having a central leader of quartz 2 feet wide at the top and
tapering to 1 foot 4 inches wide at the bottom of the shaft. The dip,
as shown by the walls of the shaft, is 70° N. The central quartz
mass is spoiled with cassiterite, and the altered granite on either side
(•out a ins recognizable grains of tin oxide.
The south vein lies 500 to 600 feet south of the middle vein. This
vein is much narrower than the veins on the north, having an aver-i
age width of about 1 foot. The strike, as shown near the shaft, is
N. 50° W., and the dip 50° N. The vein walls are sometimes defined
by a clay selvage one-sixteenth inch wide, but more often show a
gradual fading off into the granite.
It will be noticed from what has been said that the veins are all
well defined at the surface and carry good values in tin ore, but that
the ore apparently dies out in depth. Further development is needed
to establish the existence of the ore at a greater depth than 50 feet,
but it is believed that the veins have been thrown by local slips or |
faults and will be found by crosscutting from the bottom of the pres-
ent workings. The character of the fissures and the nature of the
ore both indicate that 1 he veins are the result of deep-seated agencies,
and are not merely segregations due to descending surface waters, j
For this reason it is believed that further exploration will develop
well-defined tin veins.
TUNGSTEN ORE IN EASTERN NEVADA.
By F. B. Weeks.
A hubnerite-bearing vein was discovered about 12 miles south of
Osceola, Nev., in 1900. It occurs in the foothills on the west slope
of the Snake Mountains, near the base of Wheeler Peak. The near-
est railway point is Frisco, Utah, on the Oregon Short Line Railwaj7-,
about 100 miles distant.
The country rock is a rather coarse porphyritic granite, composed
of quartz, mica, and hornblende, and having a rudely bedded structure
parallel to that of the overlying Cambrian quartzite, which dips 20°
to 25° SSW. The vein cuts across this granite, striking N. 68° E.
and dipping 05° NW. The main vein is normally about 3 feet wide,
pinching in places to a few inches, but rapidly regaining its usual
width. Several smaller veins, from a few inches to a foot in width,
outcrop on the slopes and can be traced to the main vein, entering it
at a sharply acute angle. The main vein was traced for a distance of
2,100 feet by croppings and float from its outcrop near the base of the
lowest foothill up the slope of the mountain.
Sufficient development had not been made at the time of visit to
determine the extent of ore deposition. The vein walls are well
defined. Where the vein has its average thickness, it is formed of
milky-white quartz, carrying a large amount of hubnerite. Where
the vein pinches, the quartz is schistose, and the ore is in small
stringers and small in amount. The ore occurs in solid masses, fre-
quently attaining a thickness of G to 12 inches. It is also disseminated
through the quartz in thick plate-like forms, and also occurs crys-
tallized with the quartz crystals. Small shoots of ore penetrate the
country rock for a few inches. The vein material is easily crushed,
and the hubnerite, because of its weight, can be readily separated
by jigging.
At one locality on the vein there was a somewhat remarkable
occurrence of the ore. It was found in large bunches or blocks aver-
aging 75 per cent tungstic acid, and from a small space 4^ tons of ore
were obtained. Scheelite has been found in small bunches and
streaks with the hubnerite.
More recent information regarding the development of this ore
body may be found in a paper by Mr. Fred B. Smith in the Engineer-
ing and Mining Journal, volume 7:>, pages 304-305, 1902.
lit:;
GEOLOGICAL SURVEY PUBLICATIONS ON QUICKSILVER, PLATINUM, TIN.
TUNGSTEN, CHROMIUM, AND NICKEL.
The principal publications, by the United States Geological Survey,
on the metals here grouped are the following:
Becker, G. F. Geology of the quicksilver deposits of the Pacific slope; with
atlas. Monograph XIII. 486 pp. 1888.
Quicksilver ore deposits. In Mineral Resources U. S. for 1892, pp.
139-168. 1893.
Blake. W. P. Nickel: its ores, distribution, and metallurgy. In Mineral
Resources U. S. for 1882, pp. 399-420. 1883.
Tin ores and deposits. In Mineral Resources U. S. for 1883-84, pp.
592 640. 1885.
Brooks. A. H. An occurrence of stream tin in the York region. Alaska. In -
Mineral Resources U. S. for 1900, pp. 207-271. 1901.
Christy, S. B. Quicksilver reduction at New Almaden [California]. In Min-
eral Resources U. S. for 1883-84, pp. 508-5:36. 1885.
Glenn, W. Chromic iron. In Seventeenth Ann. Rept., Pt. Ill, pp. 201-273.
1896.
Hobbs. W. H. The old tungsten mine at Trumlmll, Conn. In Twenty-second
Ann. Rept., Pt. II, pp. 7-22. L902.
Kemp, J. F. Geological relations and distribution of platinum and associated
metals. Bulletin No. 198. 05 pp. 1902.
Packard, R. L. Genesis of nickel ores. In Mineral Resources U. S. for 1892,
pp. 170-177. 1893.
Rolker, C. M. The production of tin in various parts of the world. In Six-
teenth Ann. Rept., Pt. Ill, pp. 458-538. 1895.
Ulke, T. Occurrence of tin ore in North Carolina and Virginia. In Mineral
Resources U. S. for 1893, pp. 178-182. 1894.
Weed, W. H. The El Paso tin deposits [Texas] . Bulletin No. 1 78. 0 pp. 1901 .
Weeks. F. B. An occurrence of tungsten ore in eastern Nevada. In Twenty-
first Ann. Rept,, Pt. VI, pp. 319-320. 1901.
104
COPPER.
The papers here presented represent the results of the last year's
field work by the Survey in various copper-mining districts. These
papers give, practically, a summary of the copper-mining industry of
the United States, with the exception of the important Lake Superior
district. The Lake Superior copper deposits were examined by the
Survey at an early date, and the resulting report will be found cata-
logued in the "List of Survey publications on copper," on page 186.
Other districts producing copper, but to a less value than the precious
metals, will be found discussed under "Gold and silver,1' pages 31
to 90.
ORE DEPOSITS OF BINGHAM, UTAH/'
Bv J. M. BOUTWELL.
INTRODUCTION.
Field work. — During the field season of 1000 a detailed geologic
examination of the Bingham Canyon district in the West Mountain
Mining District, Utah, was conducted under the immediate direction
of S. F. Emmons, geologist in charge, by Arthur Keith and J. M.
Boutwell. The areal mapping was taken up in the summer by Arthur .
Keith and J. M. Boutwell and continued into the fall by the latter,
and the ore deposits were studied in the winter by J. M. Boutwell.
In the summer of 1900 G. II. Girty was engaged for one week in
special paleontological studies in this field. During brief visits by
the writer in 1901-2 additional data on special areal and economic
problems were obtained.
An area of 24 square miles, embracing the Bingham Canyon mining
listrict, was mapped geologically on a scale of 1,666+ feet to the inch.
Those portions of the Oquirrh Range which adjoin this area on the
lorth, west, and south were studied en reconnaissance, and the ore
leposits in all accessible underground workings were examined.
)wing to the fact that the geologists engaged in this work were
letailed to other fields during the field season of 1901 and 1902 for
exceptionally long periods, insufficient time for the earlier prepara-
|ion of this report has remained. The complete report on the results
■The complete report, of which this paper is an abstract, will appear at an early date asa
|roft'ssiomil paper.
105
IOC) CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
of these studies is now well advanced, however, and will appear
shortly. In the present sketch, conclusions on several important
economic problems must be reserved, awaiting results of special
investigations now being conducted ; and those here given are tenta-
tive and subject to revision in the complete report.
A brief sketch of the geography, history, and production intro-
duces general statements on such major features of areal geology as
stratigraphy, intrusions, general structure of the Oquirrhs, and struc-
ture of the district; and on such major features of economic geology
as the character and occurrence of the ores, placer deposits, and com-
mercial considerations.
GEOGRAPHY.
The Bingham district, which is the chief mining section in the
West Mountain Mining District, lies in the north-central part of Utah]
in latitude 112° 9' north, longitude 40° 32' west, and is situated on the
east slope of the Oquirrh Range, 20 miles due southwest from Salt
Lake City. It is connected with the main line of the Rio Grande
Western Railway by a branch line which extends westward from
Bingham Junction (11 miles due south of Salt Lake City) a distance
of 14 miles to Ihe main settlement in Bingham Canyon.
The Oquirrh Range, the most eastern of the desert ranges of the
Great Basin, lies 25 miles west of the Wasatch Mountains, and
extends in a general north-south direction southward from Great
Salt Lake for a distance of 30 miles. In its general form it may be
likened to that of a mason's trowel, with a handle-shaped portion at
the north expanding at a point about 12 miles south of the lake from
an average width of 6 or 7 miles to a width at the head of the blade
of about 15 miles, and then gradually narrowing southward for a dis-
tance of about 18 miles to a point.
The main slorjes rise rapidly from elevations of about 5,000 feet
on the surrounding desert — except at the junction with the Traverse)
Mountains on the east and the Stockton bench on the west — to eleva
tions on the main divide of over 9,000 feet at the northern and over
10,000 feet at the southern portion of the range. These general slopes)^
to the east and west are deeply incised by many narrow, stecp-sidecH
canyons, which extend from the deserts far in toward the main divide
on comparatively gently rising, partially graded slopes, and then rise
abruptly by exceedingly steep slopes. The slopes inclosing these i
canyons are steepest at the lowest and highest portions, being often I
precipitous immediately over the narrow, occasionally graded canyor
bottoms, and similarly steep and ledgy along the major divides
while a partially graded slope sometimes marks the intermedial
stretches. These topographic characteristics are also true of th<
branches and subbranches of the main canyon, with the qualitica
tion that grading is much less advanced.
Snow falls commonly in late October, accumulates to great depths
boutwkll.] ORE DEPOSITS OF BINGHAM, UTAH. 107
and lasts until late in May. The range as a whole is not well watered.
In the region embracing Bingham Canyon only the main canyons and
their immediate tributaries carry water, and after the spring passage
of the accumulated precipitation of the winter the flow gradually
decreases until in mid and late summer water becomes scarce, occa-
sionally disappears for considerable stretches from the stream beds
during the day, and seeps through the discrete material constituting
the stream beds in their lower courses. Several good springs are
known in the range, such as that in Ophir Canyon, those at the head
of Butterfield Canyon, and that in Tooele Canyon. In the vicinity of
the mining regions, however, the main sources of water supply for
domestic and commercial use are subterranean courses tapped by
underground workings.
The vegetation is relatively sparse. This fact is doubtless due to
the steepness and ledgy character of the slopes, and consequent thin-
ness of the soil, and to low precipitation. Although more favored
than man}^ of the basin ranges, the Oquirrhs, particularly in the region
about Bingham, support neither the variety nor the extent of vege-
table growth which flourishes upon their more loft}7 and better watered
neighbor, the Wasatch Mountains. Sagebrush (Artemisia) is the chief
growth on the lower slopes adjoining the deserts. Scrub oak with an
occasional cactus plant (Puntia vulgaris), juniper, spruces, and some
pine characterize the middle elevations; and mountain mahogany,
certain grasses, and Alpine varieties of wild flowers alone inhabit the
higher peaks.
HISTORY AND PRODUCTION.
The Bingham district is unique in that it includes the oldest recorded
mining claim in the State, is the only district in Utah in which placer
mining has been successfully prosecuted, and to-d&y leads the camps
of Utah in the production of copper. Only the more important stages
in the extremely interesting and instructive history of this unique
camp may be noted here.
Early in the fall of 1863 ore was discovered by George B. Ogilvie,
an apostate Mormon, near the head of the main Bingham Canyon.
On September 17, 1863, each of the 25 members of the Jordan Silver
Mining Company formally located there " for mining purposes " one
claim "of 200 feet each and one additional claim of 200 feet for the
original discoverer. "rt This is the earliest recorded mining claim in
Utah. Active prospecting led to the discovery and location of prom-
ising croppings, but lack of facilities for transportation rendered
extensive mining operations at this time impracticable. "The first
shipment of ores from Utah was a carload of copper ore from Bing-
ham Canyon, hauled to Uintah on the Union Pacific, and forwarded
by Walker Brothers to Baltimore in June, 1868. "6
a Records at office of surveyor-general of Utah, Salt Lake City.
''Bancroft, H H , History of (Mali, p. 741.
108 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
Iii 1870 the connection of the Union Pacific and Central Pacific
railroads by the Utah Central with Salt Lake Citj^, the inauguration of
the branch road to Bingham, the gradual removal of the early oppo-
sition of Mormon authorities to the entrance of their followers into
mining operations, the results of experiments in the reduction of
local ores, and the successful exploitation of the Emma mine and
adjoining properties in the Wasatch Mountains, all combined to
stimulate mining activities in Bingham. Many bodies of lead ore,
mainly carbonate, were exploited. The first efficient development of
the mines of the district was conducted by Messrs. Bristol & Daggett
in the Winamuck and Spanish, and the largest body of argentiferous
lead ore was developed in the Jordan and Galena mines. In 1874
the bulk of lead-carbonate ore was exhausted, and in the Wina-
muck, Neptune, Kempton, Spanish, and Utah sulphides had been
encountered.
Special attention was directed toward saving the gold in the super-
ficial oxidized portions of the ore shoots in the silicified limestones.
Various experiments in milling and cyaniding were conducted, and
large stamp mills were erected. Despite claims that in special cases
cyaniding was successful, the general opinion prevails that the pres-
ence of copper necessitated the use of so inuch cyanide that no profit
could be made, and, further, that the siliceous gold ores of Bingham
have never been worked successfully. In the early eighties there
were developed in the outer western slopes of the range bodies of
carbonate ore which continued to afford an increasing output for
about a decade. In 1801 and 1 S02 the leading productive mines were
the old Jordan and Galena, Brooklyn, Highland, Telegraph, York,
Petro, and Yosemito mines, [n L893 the decline in silver brought
this period of activity to a close.
A few years later the discovery of pay shoots of sulphide-copper ore
at a time of strong demand for copper and a rise in the market value
of lead inaugurated a new era in the camp. Reduction of copper
sulphides having been successfully conducted, and the value of the
Bingham copper ores having been demonstrated in 1890 on a shipment
of 5,000 tons from the Highland Boy, exploitation for copper was
vigorously begun and has continued to the date of writing. This has
resulted in the disclosure of strong and valuable shoots of low-grade
copper-sulphide ore.
These bodies are now worked on both a large and a small scale.
The largest ones are controlled by consolidations, including the Utah
Consolidated, the United States Mining, Bingham Consolidated, and
the Boston Consolidated companies, which (with exception of the lat-
ter, which has not yet begun to ship from its well-proven shoot) trans-
port their output either by aerial tramways or narrow-gage railroad
to the Bingham terminal of the Rio Grande road, and thence by rail
to smelters built and operated by each company at Bingham Junction.
HoimvKLL 1 ORE DEPOSITS OF BINGHAM, UTAH. 109
During 1900 the total output from 32 properties aggregated 101,132
tons of ore, of an estimated value of $1,700,000. For the year 1901
the value of the output of gold, copper, and silver increased, and that
of lead decreased, with a result of a net increase in the value of the
output for 1901 over that of 1900 amounting to about $2,000,000. In
this total the copper shipments constitute the chief factor, their value
as compared with the combined values of gold, silver, and lead ship-
ments being roughly at a ratio of 23 to 16. The output for the present
rear promises to show a continued increase. The value of the approxi-
mated total output of Bingham to 1899, inclusive, as calculated from
the most complete data obtainable, is between $26,000,000 and
$27,000,000.
AREAL GEOLOGY.
Stratigraphy. — In a general sense the sediments in the Bingham
district are siliceous. Exceptions to this general character — first 1 lie
relatively thin intercalated limestone, and second the calcareous
shales — are, however, of greatest economic importance. The entire
section may be broadly divided on lithologic grounds into two parts —
i a lower, which is characterized by a great thickness of massive normal
quartzite with a few relatively thin interbedded limestones, and an
upper, which is composed largely of quartzites with black calcareous
shales, sandstones, and impure limestones.
The lower part includes three series of beds of geological and
economic interest. The first of these is a thin calcareous member
associated in quartzite with other limestones which cross Butterfield
Canyon near its head at an elevation of about 7,000 to 7,500 feet. It
carries a fauna which has been correlated by Dr. G. II. Girty with
those of Lower Carboniferous age in the Mississippi Valley. Over-
lying this is a thickness of about 1,250 feet of massive quartzite.
The second series is composed of at least two heavy limestones, which
aggregate, with intercalated quartzite, about 5,000 to 8,000 feet in
thickness. In these limestones have been found a large portion of
the ore bodies of this camp, and near the top of the lower limestone
of this series occurs a fauna characteristic of the Upper Carboniferous.
Extensive deformation by Assuring, faulting, and intrusion gives rise
to some uncertainty as to the normal succession from this point to
the top of this lower great division. The structure of an extensive
region to the south, west, and north of this immediate area, beyond
that which the writer could find time to study, must be carefully
determined before this and some other large structural problems
involving this immediate area can be conclusively settled. But the
field evidence gained by thorough study in this immediate area and
he country immediately adjacent thereto indicates that overlying
his second limestone series is a thickness of approximately 1,500 feet
m)f quartzite with intercalated thin blue limestones and calcareous
110 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
sandstones, and that over this and at the top of the lower great
division is a series of at least three limestones of a semilenticnlar
character. The lower of these limestones included the largest single
body of copper ore yet discovered in Bingham.
The upper great division of the Bingham section, several thousand
feet in thickness, is made up. in the main of normal quartzite, and
includes in addition relatively thin calcareous sandstones, calcareous
carbonaceous shales which occasionally attain a thickness of a few
hundred feet, and thin blue limestones. No particular horizon in
this series is of special economic importance. The principal bodies
known to occur in it, however, are associated with calcareous shales.
Scanty faunas indicate I he series to be of Upper Carboniferous age.
Igneous rocks. — Igneous rocks of at least two distinct types and
ages are recognized. The area studied was too Limited to afford the
data necessary to prove the origin, source, and direct ion of movement
of their magmas. Accordingly all statements concerning these sum
jects must be regarded for the present as in the nature of tentative
suppositions. In brief, molten masses have been injected into the
sediments in this area from the lowest nearly up to the highest]
These broke upward across ami along the beds in an extremely
irregular manner and cooled in the form of irregular dikes, sills, and
laccolil hs.
The petrographic character of this intrusive varies from the fine- ,(
grained, rather basic porphyry of the laccolith at Upper Bingham tq
a coarse, slightly more acid type in Keystone Gulch, and to the coarse
acid type north of Can- Fork toward its headward portion, and finally
to the altered acid type between Bingham Canyon and Carr Fork.
For general purposes these maybe considered as several fades of a
single magma characterized by the occurrence in the Bingham lacco
lith. Under the microscope thin sections appeared to be augite
biotite-diorite-porphyry, but chemical analyses show the content of
potash to exceed considerably the average potash content of diorite
porphyry and to agree with that of monzonite. Accordingly the rock
maybe regarded as an intermediate type between diorite-porphy ry
and monzonite. It occurs chiefly in the lower half of the section, and
assumes considerable economic significance, first in connection with
the main limestones, and second as the home of valuable mineral
deposits.
The second tj^pe of igneous rock within this area is restricted to the
lower slopes of the outer extreme eastern part of the range. Petro
graphically it differs from the intrusive just described in being moil
acid and allied to the andesites. No positive proof regarding the age
and origin of this volcanic body has been found. A small prospect,
tunnel exposes the andesite breccia overlying an old surface debris of
quartzite similar to that which characterizes the present slopes.
Accordingly it may be regarded as an extrusive mass which over-
boutwell] ORE DEPOSITS OF BINGHAM, UTAH. Ill
flowed and submerged an ancient topography. Nothing bearing upon
the source. of this rock has been found since the work of Mr. Emmons
in connection with the early survey of this region, when he determined
that—
the Traverse Mountains, which form a partial connection between the Wasatch
Range and the Oquirrh Mountains, * * * seem to he composed mainly of
trachyte, the flows of which extend * * * along the foothills of the Oquirrhs
so far as the mouth of Bingham Canyon. «
The date of the porphyry intrusions is not definitely fixed, although
it was probably earlier than the date of the extrusion of the volcanic
flows, and abundant underground evidence proves that it was earlier
bhan the late faulting on northeast-southwest fissures, earlier than the
period of mineralization on those fissures, and probably earlier than
jhe Assuring which preceded this period of mineralization.
Correlated studies, which the writer is now undertaking in another
leld, will, it is believed, throw much light upon the geological history
)f the igneous rocks of Bingham. So far as known, these extrusives
lave never been found to carry mineral values. An interesting eco-
lomic problem associated with this andesitic flow involves the east-
vard extension of ore bodies. For if the pre volcanic land forms sim-
dated present forms, and the andesitic breccia simply blankets an
earlier surface, then there is no structural reason why the ore bodies
n Carboniferous sediments may not be followed eastward under the
olcanic flow. On the other hand, if this volcanic mass broke up at
>r in proximity to the present surface contact, then it is probable
hat this contact descends in depth approximately vertically and
runcates the ore bodies.
Structure of the range. — The general structure of the Oquirrh
tange, so far as it has been studied, is characterized by broad exten-
ive folds and complex fracturing and faulting on a small scale. It
s not improbable, however, that further field work, which shall
xtend our knowledge beyond the limited areas that have thus far
»een studied in detail, will reveal extensive faulting.
The beds in the southern portion of the range have been folded
long northwest-southeast axes into two great anticlines, whose con-
ecting syncline is occupied by Pole Canyon. b Northward "the main
rest of the range, between Tooele and Lewiston peaks, is the rem-
ant of the flat arch of an anticlinal fold."0' The northern extension
f this anticline may be identical with the anticline which crosses
'ooele Canyon about two miles below its head. Thence the Car-
A oniferous limestones, with the overlying siliceous series above
escribed, strike eastward across Bingham Canyon until, at a point
ear its mouth, they turn up steeply on edge and strike northward.
i j
"Emmons, S. F„ U. S. Geol. Expl. Fortieth Par., Vol. II, p. 440.
blbid., p. 443.
<*Ibid.,p. 443,
112 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 3902. [bull. 213.
Beyond here the structure is not as well known. In a general way it
is believed that the beds dip northwardly and pass through several
minor folds and considerable faulting until "beyond Connor Peak
the beds of the Lower Coal Measure group are found to be pushed up
and crumpled together in short sharp folds, giving no less than three
small anticlines. "a At the extreme north end of the range, along
the general northeast-southwest strike, the dip is much disturbed and
varies from vertical and 40° N. on the mainland to 5°, 10°, and 30° S.
in Sheep Rock and outlying outcrops along the shore to the north.
Structure of the district. — The Bingham district itself thus lies in a
broad, shallow, synclinal basin which pitches gently northward and
is limited on the west by the Tooele anticline and on the east by the
abrupt Bingham upturn. Minor folds occur with various irregulari-
ties of strike, but they are relatively unimportant. Fracturing and
Assuring lias taken place very extensively throughout the district.
The amount of displacement in the instances studied is not, however,
great, rarely amounting to 100 feet.
The general distribution of these sediments and intrusives is sim-
ple, but the detailed distribution is most complex and irregular.
Briefly, the three great limestone series and the massive quartzites
which separate them occupy the southern and southeastern portions
of the area, and strike from the main divide on the west northeast-
ward through the district. The great siliceous upper series of quartz-
ites, calcareous shales, sandstones, and thin limestones overlie them
and occupjr the north and northwest half of the area. The intrusives
lie mainly in the southern portion of the area in two great divisions,
the lower, lying south of the middle limestone series (Old Jordan-
Telegraph- Yosemite and Commercial-Brooklyn limestones), and the
upper, which overlies this lime series. The sediments and their asso-
ciated intrusives disappear on the east along a generally north-south
line under the later volcanics, which in turn are blanketed by Quat-
ernary deposits. In brief, the geological map of this area may be
pictured roughly as follows: Conceive an oblong area in which the
four points of the compass lie at the four corners; draw a straight
line from the north corner to the middle of the southeast side, a sec-
ond line from the same corner to the middle of the southwest side,
and a third across the south corner in an east-west direction; then
the first line will delimit the contact between the late deposits (Quat-
ernary and volcanic) on the east and the Carboniferous on the west,
the second will delimit the great siliceous series on the north from tin
main mineralized area comprising the limestone series with separat
ing quartzites and intrusives on the south, and the third will delimit
the Lower Carboniferous to the south from the Upper Carboniferous
to the north.
« Emmons, S. F., U. S. Geol. Expl. Fortieth Par., Vol. II, p. 444.
boutwell.] ORE DEPOSITS OF BINGHAM, UTAH. 113
ECONOMIC GEOLOGY.
General. — The principal mines of this district are located on the
slopes of Bingham Canyon, of its tributaries, and of the head ward
portions of the northeastern tributaries of Butte rfield Canyon. They
have revealed valuable ore bodies of two great types, those which
occur as lenses, roughly parallel to the bedding, and those which
occur in fracture or fissure zones. Under each of these forms of
occurrence ores of copper, lead, silver, and gold occur, though the
copper lies mainly in the lenses in limestone, and the lead and silver
in fissures. For the purpose of this abstract the economic geolog3T
may best be considered with regard to character and occurrence of
ores, placers, and commercial considerations.
Character of the ores. — The ores of Bingham include a valuable
variety of the desirable metals. Thus mining activity has been devoted
successively to oxidized gold ores, carbonate ores of lead and cop-
per, sulphide of lead, and finally sulphides of copper. The oxidized
^old ores carried good values, but were not commercially profitable.
Although some of the gold was free, no satisfactory treatment of its
ares was obtained, the commonly accepted explanation being that the
presence of copper required too much cyanide to leave a profit. The
carbonates of lead and silver carried high values and were treated
with comparative success, but are to-day worked out. Lead-silver
sulphides later assumed commercial importance, and under the influ-
ence of good market values lead is still extensively mined. This ore
is made up of galena, tetrahedrite, considerable zinc sulphide, pyrite,
and chalcopyrite, with a gangue of quartz and calcite. The mainstay
3f the district, however, is copper sulphide ore. This is composed of
cupriferous pyrite, chalcopyrite, and the black sulphides of copper,
which may prove to be chiefly tetrahedrite and chalcocite, with occa-
sionally a little galena, zinc, and a siliceous gangue.
Pyrite (sulphide of iron with copper as an impurity: iron pyrites),
-he most common metallic mineral known in Bingham, forms the bulk
)f immense replacement ore bodies in limestone, plays a secondary
*61e in fissure ores, and is freely disseminated through the igneous
*ocks. Although large masses of perfect crystals of exceptional purity
tfere found, its more prevalent occurrence is in massive form inti-
nately combined with chalcopyrite, small amounts of bornite, pyrrho-
ite, and alteration products of primary sulphides. Chalcopyrite
sulphide of copper and iron : copper pyrites) occurs scattered in small
)atches throughout bodies of massive pyrite in limestone associated
vith pyrite bands; in fissures of lead-silver ores, and in grains dis-
eminated through the main porphyry bodies. It appeal's, from
cached and unleached specimens, and from a study of thin sections,
hat much of the copper of cupriferous pyrite occurs as chalcopyrite
n the state of a i)hysical mixture with pyrite. Certain samples of
Bull. 213—03 8
114 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. |bull. 213.
rich black copper-sulphide ore associated with cupriferous pyrite from
the large mines have been found by Dr. H. N. Stokes, chemist of the
Survey, to consist mainly of tetrahedrite (copper-antimony sulphide
with silver, zinc, and arsenic associated; gray copper). This is not
like normal tetrahedrite of some camps, and is believed to be inti-
mately associated with chalcocite (black sulphide of copper) and pos-
sibly some melaconite (black oxide of copper).
In this camp tetrahedrite occurs occasionally in crystalline form,
but more commonly, and far more prevalently than has hitherto been
recognized, under two facies of the massive form. In the copper ores
in limestone it occurs in large masses as a dull-black powder and a
crushed gray metallic substance associated with cupriferous pyrite.
In the lead-silver fissure ores it occurs in regular bands and patches,
is fine grained, compact, homogeneous, with metallic luster, steel-lead
gray color, pale-bronze line, and gives a dark-red streak. This
species, freibergite, contains silver, and is commonly mistaken for
ruby silver. Exceptionally fine crystals of enargite (sulphide of
copper and arsenic) were obtained from a single occurrence. An
excellent specimen of pisanite (hydrous sulphate of copper and iron),
an alteration product of copper ores, was supplied by Mr. A. F.
Holden, who suggested that it might be this mineral. It is believed
that this is I he first occurrence of the mineral reported in this
country. Other copper-bearing minerals which occur in Bingham are
bornite, covellite, cuprite, malachite, azurite, chalcanthite, native
copper, and possibly cubanite, binnite, bournonite, and tennantite.
(ialena (lead sulphide), which forms the bulk of all the present
shipments of lead and silver, occurs in tabular bodies in or adjacent
to fractures which intersect limestone^ shale, porphyry, or quartzite,
or in two or more of these. Although it is sometimes scattered in
small amounts through the limestone, it occurs more commonly in
irregular bands roughly intercrustified witli similar bands of pyrite
and chalcopyrite, calcite or quartz, and blende. Lead occurs here
also in cerussite (carbonate of lead), anglesite (sulphate of lead),
yellow oxide, and dufrenoysite.
Silver values probably lie chiefly in galena. It is a matter of com-
mon report among mining men that the granular variety of galena
carries higher silver values than the cleavable variety. An assay by
Dr. E. T. Allen, chemist of this Survey, of a composite sample of
cleavable galena from four of the best-known silver-lead mines in
Bingham, shows 18.9 ounces silver present, and of a sample of granu- 1
lar galena only 10 ounces. Native silver has been reported, but was
not found during the present survey, although it was suspected to
occur. Ruby silver has not been found. Crystalline specimens
reported to be ruby silver have been proved, on study of the crystal
forms, to belong to a different crystal system, and on chemical deter- 1
minations by Dr. Ilillebrand and Dr. Allen, of this Survey, have been
boutwell.] ORE DEPOSITS OF BINGHAM, UTAH. 115
found to be tetrahedrite. In a mixture of the crystal and massive
tetrahedrite Dr. Allen found 325 ounces of silver, which indicates
that the mineral usually called ruby silver is the silver-bearing spe-
cies of tetrahedrite, freibergite.
Gold has been mined in Bingham in two forms — in its primary
occurrence in country rock and in its secondary occurrence in detri-
tal deposits. In the former it has been found in pay values included
in sulphides, both in fissure ores, in pyrite, and possibly in galena
and in tetrahedrite, and in replacement bodies in limestone. In
the secondary occurrence rich gravel has been worked, though no
free gold was obtained during the study of the camp. Unlike the
primary gold, which is said to have been rough and jagged, placer
gold is said to occur in thin beaten scales and washed nuggets. Flour
gold has been found to be evenly distributed through the gravel for
a distance of 30 feet above bed rock. In the early days when gold
ores were mined from the silicified superficial portions of the great
mineralized limestones and treated in stamp mills, only a portion of
the gold was found to be free and no successful process was secured
for treating the remainder of the gold content. In the present low-
grade copper ores gold is an important associate, for it is the gold
contained in these ores, low as it is, which renders more than one
Bingham property a commercial possibility.
Zinc is present in the gangue of lode ores and is most abundant in
those which lie within porphyry. It forms uneven layers roughly par-
allel to those of its associates, and irregular bunches and stringers inter-
mixed with them. A few minute crystals of the light honey-yellow
variety and of the black variety occur in vugs in veins, but by far the
greater portion of this mineral is of the blackjack type and occurs
occasionally granular, but usually massive cleavable. The Bingham
occurrences of zinc deserve the attention of owners (see p. 121).
Some other minerals which under suitable commercial conditions
are of economic value occur here sparingly. Molybdenum occurs in
grains and bands in the porphyry of the Bingham laccolith, but in
too small quantities to be of economic value. Gypsum is found
in fibrous and selenitic form in small amounts in calcareous shale.
Barite in radiating plates lies at the cores of some veins. Iron is
found besides in copper sulphides, in magnetite, specularite, and
limonite, but does not assume commercial importance. In brief,
then, the valuable ores of Bingham are the copper-iron-gold-silver
replacement ore, and the lead-silver-copper-gold lode ore.
Values. — The values of the Bingham ores average very low. Pay
ore is widely distributed; prospecting in country rock in any part of
the camp rarely fails to disclose some metals, but bonanzas have
rarely been found. With very few exceptions the ore which is being
mined to-day carries such low values as to render its successful
extraction and reduction either a close-smelting or a concentrating
116 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
proposition. Thus in certain instances it is the accessory gold, lead,
and silver contents which raise the total value of low-grade copper
ores safely above the commercial limit. It has been reliably esti-
mated that a profit can not be guaranteed on a mixed copper ore
from Bingham whose aggregate value falls below $6. It is under-
stood, however, that this minimum limit has been lowered and may
reasonably be expected to be still further reduced. The combination
of a few higher grade bodies, several of medium grade, and many
of low grade, together with the variety of types of ore, including cop-
per, lead-silver, and gold, has proved most essential. This fact, by
providing the mining industry against early exhaustion, baseless
speculation, and market fluctuations, has made possible practically
continuous mining operations from the date of the earliest mining in
Utah to the present.
Little reliable information regarding the copper values is available.
The aA^erage of the assays of three characteristic shipments from a
typical fissure mine shows a copper content of G.5 per cent. In the
limestone replacement ore bodies the copper values are understood to
run somewhat lower. Thus the average of three averages of a great
number of assays on ore from two of the great copper properties shows
a copper content of between 3 and 4 per cent. An assay of an average
shipment from ore in a fissure in quartzite and porphyry gave 44.25 per
cent lead, and the average of shipments for three years from a mine
on a fissure in limestone is reported to be 45 per cent. These facts]
la ken in connection with assays from many mines, warrant, the con-
clusion that the average of typical lead ore in Bingham is about. 45
per cent lead. The silver content in two famous lead bonanzas ^aver-
ages 25.18 ounces per ton. In sulphide-copper ore from the replace-
ment bodies silver runs from 2 to 4 ounces, and in fissure ores it
ranges from 18 to several hundred, while ore from a fissure in quartz!
ite and porphyry affords an average, based upon assays of three nor-
mal shipments, of 8U) ounces. Gold values from the crests of the]
great replacement bodies average $10 to 1-12 a ton. Those in cuprif-
erous pyritic ores average about $2, and those in the porphyry ore!
average about 25 cents. The pay in detrital deposits is stated in the
description of placers.
Occurrence of the ores. — The productive area in the Bingham dis-
trict is not restricted to any local ore deposit nor to a single zone of;
deposits. The most important productive belt comprises those mas-
sive limestones described under "Area! geology" as the middle and
upper series of the lower great division. They have been found to
be productive from the desert on the east to West Mountain on the
west, a distance in a direct line of about 3| miles. The known pro-]
ductive area of Bingham extends from the Richmond mine on the
east to the Star mine on the west and from the Midland and Broad
boutwell] ORE DEPOSITS OF BINGHAM, UTAH. 117
Gauge mines on the north to the Queen and Lucky Boy mines on the
south, an area of approximately 15 square miles. The vertical range
of known ore deposits is marked by those in the Zelnora (8375) and
the lowest levels in the Brooklyn (5875) and Dalton and Lark (5810),
a vertical extent of 2,565 feet.
Ore bodies occur in each of the lithoiogic types of rocks of the dis-
trict, including limestones, quartzite, shale, and ijorphyry. The lime-
stones, which have afforded the largest ore bodies, compose the main
belt and include the Brooklyn-Telegraph and the Commercial and
Highland Boy members. No ore bodies are known in the massive
dark-blue limestone underlying these series, but some have been
found in the siliceous limestone above the Highland Boy horizon and
in the thin mottled limestone of the Petro-York "bedded vein."
Although ore occurs in the calcareous shales which characterize the
great siliceous series over the main limestone belt, exploration shows
that the rich lead-silver bodies formed under rather than within these
shales. High-grade lead-silver ore carrying minor values of copper
and gold occur in fissures which transect the quartzite, porphyry, or
shale.
If we may judge from the occurrence of known ore bodies, two litho-
iogic types appear to have exerted the strongest influence upon their
formation, namely, limestone and porphyry; for it is in the main lime-
stones in the neighborhood of intrusive masses that the large shoots
of copper sulphides have been discovered. Thus the country rock
inclosing the great Highland Boy shoots overlies a broad, irregular
dike sill. The newly proven shoot in the Boston Consolidated over-
lies the great Last Chance intrusive, and is cut and overlain by por-
phyry. The bodies in the Jordan-Telegraph-Brooklyn and in the
Commercial- Yosemite limestones are complexly associated with dikes
and sills.
In influencing the position, form, and extent of ore bodies, defor-
mation of the country rock appears to have constituted a third impor-
tant factor in the formation of ore bodies, for in Bingham those
limestones which have been intruded by porphyry inclose the larger
and more numerous shoots in regions in which strong fracturing and
Assuring have occurred. The entire country rock is excessively frac-
tured, crushed, and fissured. These fissures are distinct loci of move-
ment, of considerable horizontal and vertical extent, bounded by
highly slickensided and polished walls, and possess in a general way
the form of planes, but in detail exhibit many inequalities. They
are not restricted to a few distinct trends, but trend in about equal
number toward practically all points of the compass.
The ore-bearing fissures, however, in far the greater number trend
toward the northeast and southwest, and dip steeply to the northwest.
Underground evidence shows that Assuring took place in northeast-
118 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
southwest directions, and that later, following a period of mineral-
ization and Assuring and faulting in northwest-southeast directions,
recurrent Assuring and faulting took place on northeast-southwest
planes. It is in connection with the great limestones which have
thus suffered intrusion and recurrent Assuring and faulting at several
periods that the larger bodies of copper ore occur, and in the fissures
that the smaller but valuable bodies of lead-silver ore formed.
The copper-sulphide ores occur in the general form of flat, attenu-
ated lenses, mainly Avithin the great" limestone beds, and lie roughly
parallel with the stratification. In the vicinity of fissures these bed-
ded ore bodies thicken into well-marked shoots which, following the
trends of the fissures, often pitch slightly. When these shoots display
distinct structure, that of the original stratification is seen to be per-
fectly preserved.
The fissure ores carrying lead and silver, with subordinate amounts
of gold and considerable zinc, differ much from the copper ores in
the character of their occurrence. They form tabular bodies which
mayor may not be sharply limited by fissure walls, and extend sev-
eral hundred foot horizontally and in depth. These lodes occur as a
series of thin, sinuous, irregular pay streaks, which combined consti-
tute bodies which are relatively thin when the fissures lie in a quart zite
or porphyry country, but arc of much greater width where the fissures
cut calcareous bods. This selective act ion, indicated by bulging or
increased lateral extent, which is exhibited between calcareous and
noncalcareous rocks, is manifested in precisely similar manner
between different bods of the same calcareous mineral. In addition
to this change in the size of fissure veins, lesser variations occur,
within lenses lying in a noncalcareous country, which constitute rec-
ognized shoots. The structure of the fissure ore consists of a rough
banding of the several constituent minerals which form the vein, in
roughly systematic arrangement 'from the center of the vein to either
wall. In brief, there is a rough comb or crustified structure.
The copper- gold ores inclosed in the porphyry of the Bingham lac-
colith, however, present an interesting form of occurrence of an
entirely different character. This ore, which consists of grains of
cupriferous pyrite and chalcopyrite, is thoroughly disseminated
throughout the intrusive mass, and seems to increase slightly in value
in the areas which have suffered the maximum shattering and
crushing.
The facts which have been observed with regard to the occurrence
of the ore deposits of Bingham afford evidence for a very reasonable
explanation of their formation, and these conclusions lead to several
suggestions which it is hoped may prove to possess much commercial
value. As the present abstract does not admit of such theoretical
discussions, however, they must be deferred until the publication of
the complete report.
boutweli,.] ORE DEPOSITS OF BINGHAM, UTAH. 110
PLACER DEPOSITS.
History of placer raining. — Bingham Canyon stands alone among
the numerous successful mining districts of Utah as the only locality
in the State where placer mining has been successfully prosecuted.
Free gold was first discovered in Bingham in 1864 by a party of veteran Cali-
fornia miners who, returning from Montana to pass the winter in Salt Lake, pros-
pected the canyon in the early part of that year. It was not, however, before
the spring of 1805 that much work was done in prospecting for that metal/'
It is also stated6 that gold in the gravels was first discovered in the
fall of 1860 and was mined then by Peter Clays and G. W. Crowley.
The chief period of placer mining in Bingham extended from the
date of discovery to 1871. Since then there has been a steady decline
in the output of placer gold, except during the year 1881, until the
present day. As late as 1898, however, the Arganaut was hydrau-
licked at the mouth of Carr Fork, and at present desultory work is
conducted by the veteran gravel miner Bartholomew Gardella upon
gravels on the continuation of this channel known as Dixon Bar and
at the head of Bear Gulch. Late in the nineties the West Mountain
Placer Company conducted extensive explorations in the gravels
at the bottom of main Bingham Canyon, immediately below Dry
Fork, and reported that gold occurred there in pay quantities, but
that they were unable to handle the water. Since then (his property
has remained idle.
Occurrence. — Detrital gold has been found at several points in
Bingham in gravels of different ages. These lie at various elevations
in the canyon, and range from the rock bottom of the present canyon
up to points on its side slopes several hundred feet above. They indi-
cate former positions of the canyon bed, and the pay inclosed by the
gravels then deposited shows that the streams were then transporting
gold shed into them from their inclosing walls, and depositing it with
their other burdens. The deepening and widening of the canyon
through the same agencies which are to-day continuing that work
resulted in cutting down through and removing the gravels from the
early stream beds. So the high gravels or bars seem to be remnants
of stream gravels deposited during the earlier stages of canyon
cutting, and, occurring at different levels, they mark successive
stages in the work of cutting down to the present level.
The bars consist of isolated deposits of waterworn gravel tying
upon waterworn bed rock at the noses of spurs and at such points as
have escaped removal by development of the present topography. In
some cases these are patches on the sides of the canyon — in one
instance there is a complete section of an earlier channel showing
both walls, which are truncated upstream and downstream by later
transverse valleys; and in another, extensive buried stretches of an
"Murray, J. R., Mineral Resources, Territory of Utah, 1872, i>.
''Personal communication, 1900, from Daniel Clays.
120 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bttll. 213.
earlier channel have been preserved. The only possibility for placer
mining on a large scale is in the gravels which cover the bed rock of
the main canyon in its lower extent to a great depth.
Values. — Values, as a rule, have been good. While some of the
high-lying patches panned rather low, rich bars were not uncommon.
Gravel from the bottom of main Bingham Canyon in this same vicinity
is reported to have brought 18 to 20 cents a yard. The pay levels of
the West Mountain gravel are said to yield 8 to 10 cents a pan, and
some of them 6 and 9 and 15 cents a yard. A recent sampling of the
gravel in the Arganaut cut shows that the lower 30 feet of gravel
averages 6 cents per cubic yard, and that the lowest G feet averages
18 cents.
In general the gold is coarse, varying from half an ounce downward.
A nugget reported to be the largest ever found in Utah was discov-
ered in the Clays bar near the mouth of Damphool Gulch by Daniel
Clays. This is stated to have weighed 17 ounces 15 pennyweight,
and to have been valued at $128. The fineness is generally considered
to range from 850 to 875. In round numbers the total known output
of placer gold from Bingham is about $1,500,000, while the entire
output would undoubtedly aggregate about $2,000,000.
( '< >MMEROIAR CONSIDERATIONS.
Although in the economic work of the Geological Survey "the
fundamental principle * * * has been that its primary object is
to determine the general laws which govern the foundation of ore
deposits," a matters come to notice on which suggestions have been
given which have frequently proved of immediate commercial value.
During the progress of the work in Bingham, several points have
appeared in which it would seem that some improvement would be
advantageous. It, is hoped to develop some of these suggestions in
the complete report. At present they may be barely stated.
The geology of Bingham presents many extremely discouraging
difficulties. A great thickness of rocks of similar physical character
and structure have been intruded, crushed, and faulted to a degree
of complexity which might reasonably have been considered impos-
sible. Instances are known in which good miners and able experts
have been thoroughly baffled by this complexity, and so it is not
strange that mining men familiar with the camp should believe that
successful mining in Bingham requires, to an unusual degree, thor-
ough practical geological experience. One familiar with these prob-
lems appreciates the significance of the common saying among miners,
that to direct underground work in Bingham successfully one must
have ' ' grown up with the camp. "
The irregular porphyry bodies have led to unwise exploration
through failure to comprehend their origin, and thus their form and
« Emmons, S.F., Eng. and Min. Jour., Vol. LXXIV, p. 48.
BOutwell.] ORE DEPOSITS OF BINGHAM, UTAH. 121
extent. The Bingham porphyry is intrusive in origin. It was forced
into the country rock from "below along the ways of least resistance
when in a molten, semiliquid state, and on cooling assumed forms of
irregular dome-like masses, laccoliths; roughly vertical wall-like bod-
ies, dikes; and nearly flat bed-like bodies, sills. Thorough examina-
tion of the form of the body on the surface should give the key to the
type of the intrusive, and thus determine the most direct and economic
method of attack.
Again, faulting, that common and characteristic feature of Bingham
structure, has caused loss through misdirected exploration. Exten-
sive detailed underground work throughout the camp goes to show
that the prevalent idea among Bingham miners, that faulting is
systematically of one type, with the character of displacement uni-
versally the same, is an error. Instances are at hand which x>rove
that many types of faulting exist at Bingham, and that the character
of the displacement is not restricted to one form, but includes many.
In view of this fact each case must be worked out on its own evidence.
Further, no little time and money have been lost by guessing on the
direction of offset of ore bodies by faulting, and driving aimlessly in
accordance with such guesses. When a lens of copper ore which lies
along the strike of the beds and well within a thick limestone is found
to be cut, displaced, and temporarily lost by faulting, it is usually
advisable, in case the surface geolog}7 does not afford a clue, to drive
to the nearest wall, quartzite foot or hanging. There the member
which lias been brought opposite to the contact may be found, the
usual criteria indicative of the direction of movement observed, and
the fault duly proved. The fact that a lens of copper sulphide
pinches when followed down on its dip is not necessarily an indication
that the ore has permanently disappeared. It is the habit of such
lenticular bodies to thicken and thin irregularly. Accordingly con-
tinued exploration in depth might reasonably be expected to be
rewarded by the discovery of similar lenticular ore shoots. Although
copper shoots of this type attain great size and value in the large
limestones, they are erratic and should not be expected to prove as
constant in extent, either perpendicularly or horizontally, as smaller
but more faithful fissure ore bodies.
The zinc contents of the Bingham ores have never received the
attention they merit. Highly zinciferous ores have not onljr been dis-
dainfully rejected, but they have been regarded as losing proposi-
tions, owing to extra smelting charges.
In several cases Bingham ores are reported to have carried regularly
15 pei' cent of zinc. In some instances values of 32 and 45 per cent
zinc have been reported in Bingham. Although these ores may pre-
sent some problems different from those encountered in camps where
zinc ores are successfully worked, it would seem highly advisable to
conduct more extensive experiments on them before abandoning ore
122 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
containing so high a percentage of this valuable metal. A recent
proposal of the American Smelting and Refining Company in the
Jordan Valley to treat zinc ore from southern Utah, the present
remodeling of the Anchor mill, and the recent thorough equipment of
the custom zinc plant of Park City, afford Bingham owners a further
opportunity to attempt to save their zinc values.
Even without either this additional saving or the discovery of new
ore bodies, the present condition of the camp is promising. Unless
the price of copper falls sufficiently to necessitate the suspension of
mining operations, the fact that the United States Mining C'ompan^
has begun regular heavy shipments from the ore shoots which have
been developed in their properties during the last few years; that
valuable additional shoots of pay ore have recently been discovered
in the Utah Consolidated property; that a valuable shoot of sulphide
copper ore of pa}7 grade has been proved in the Boston Consolidated
ground; that the work of opening and developing the consolidated
mines on the cast slope of the range, acquired by the Bingham Gold
and Copper Company, is well advanced; and that extensive bodies of
high-grade lead-silver ore have recently been discovered in the Com-
mercial and Ashland properties, assure a strong consistent increase
in the output from Bingham in the immediate future. Furthermore,
although the camp has been rather thoroughly prospected, it is rea-
sonable to expect that future exploration will reveal (1) new shoots of
valuable copper-sulphide ore in the few stretches of the great lime-
stones which remain unexplored, (2) pay lodes of the Silver Sheald
type in fissures in t lie quartzite and porphyry about the upper portion
of Bingham Canyon, and (3) new lead-silver bodies of the Montezunia-
Ben Butler-Erie type in fractured or fissured zones in or adjacent to
the calcareous carbonaceous shales of the upper series lying north-
west of Bingham Canyon and Carr Fork.
COPPER DEPOSITS OF THE REDDING REGION CALIFORNIA.
By J. S. Diller.
SITUATION AND DISTRICTS.
The copper deposits of the Redding region of California lie among
the foothills and mountains about the northern end of the Sacramento
Valley, within the Redding quadrangle. This quadrangle was sur-
veyed geologically in 1901-2, with a view to discovering the general
relations of the ore deposits, and only such results can be announced
at the present time, as detailed surveys have not yet been made.
Four copper districts occur, more or less completely isolated, in which
there lias been extensive prospecting, but only the two largest, Bully
Hill and Iron Mountain, have thus far yielded paying mines.
ROCKS OF THE COPPER REGION.
Sedimentary rocks. — The copper region contains an extensive series
of sedimentary rocks, ranging from the Devonian into the Miocene,
associated with igneous masses of various ages, shaj^es, ami kinds,
which have been intercalated or intruded into the sediments. The
general abundance of fossils in the Cretaceous, Jurassic, Triassic,
Carboniferous, and Devonian sediments, from all of which large col-
lections have been made, has rendered it i>ossible to work out the
structure in detail with a high degree of probability.
Unconformities. — The great succession of sediments is wholly of
marine origin; but their relation to one another, whether conformable
or unconformable, is not easily determined, for in most cases igneous
rocks lie between them. Thus the relation in succession between the
Devonian, Carboniferous, Triassic, and Jurassic is much obscured by
igneous rocks, but between the Jurassic and Cretaceous there is a
conspicuous unconformity which represents not only a long interval
of time, but a great epoch of mountain building followed Iry erosion.
The mountain-building epoch at the close of the Jurassic was a time
of rock folding, faulting, and crushing, as well as igneous intrusion,
which greatly modified the rocks and prepared the way for the asso-
ciated ore deposits.
Relation of ores to sedimentary' rocks. — Disseminated ores occur at
many points in all the sediments of the copper region older than the
123
124 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 2lj
Cretaceous, but thus far no large bodies of ore commercially workable
have been observed in the sedimentary rocks, although such rocks
occur in the neighborhood of some of the mines. In the Afterthought
and Bully Hill districts the nearest sedimentary rocks are chiefly shales
and limestones of Triassic age; in the Black Diamond district, shales
and limestones of Carboniferous age; and in the Iron Mountain dis-
trict, shales and limestones of Devonian age. Neither the kind of
sediment (except the limestone at Black Diamond, to be noted later)
nor its age is of special importance in relation to the ore bodies.
Igneous rocks. — The more important rocks of the copper region, so
tar as the ore deposits are concerned, are of igneous origin, and of
these there is a great variety occurring in various forms. They may
be most conveniently treated in this connection as lavas or surface
flows, granitic rocks, and dike rocks.
Lavas. — The most important body of igneous rocks of this type is
an extensive series of lavas which penetrate the older formations and
lie to a large extent between the Triassic and Carboniferous strata.
The volcanoes from which they flowed burst forth during the closing
stages of the Carboniferous, for the tuffs resulting from the earliest
eruptions contain carboniferous fossils. The thick mass of volcanic!
made up of tuffs and sheets of lava extends into the Triassic, for fos-
sils of that group are found in the later tuffs. Many of the inter-
bedded tuffs contain minute fossils of marine organisms, suggesting
that the eruptions were largely submarine.
M uch of t lie lava contains porphyritic quartz, and in general may be
designated metarhyolite, but a large part, being without- free quartz
and less siliceous, has the appearance of metaandesite. A peculiarity
of many of these rocks is that they are rich in soda.
A great belt of these ancient volcanic rocks lies east of the Car-
boniferous limestone, between Squaw Creek and the McCloud, and
forms a succession of prominent peaks from Bollibokka Mountain,
through Salt Creek Mountain, Minnesota Mountain, Town Mountain,
and Horse Mountain to Pit River and beyond a lower ridge to the
Sacramento Valley. A second belt west of this lies about the Sacra-
mento River, embracing the Iron Mountain district and extending as
far north as Backbone Creek. These two areas of ancient lavas, with
associated dikes, include all the productive copper mines and the
most active prospects of the region.
Ancient lavas occur also about Bagley Mountain, west of the Great
Bend of Pit River, but they are usually of more basic types than
those mentioned above.
Granitic rocks. — Two areas of granitic rocks occur, one about
Shasta, between Keswick and Iron Mountain, and the other about,
Bayha and Pit River ferry, but neither of these masses is yet known
to contain important bodies of copper ores, although \fo.&y contain
some auriferous quartz veins. Dikes from these granitic masses cut
dillek] COPPER DEPOSITS OF REDDING REGION, CAL. 125
the lavas noted above, and are themselves intersected locally by
dikes of diabase, so that in order of age the granitic rocks come
between the great mass of older lavas and younger dike rocks.
Dike rocks. — The dikes are of a large variety of rocks, and range
in size from a few inches to a hundred feet or more in width. They
intersect older igneous rocks as well as sedimentary rocks, and are
widely distributed throughout the field. Some are decidedly porphy-
ritic, but the majority are fine grained and compact, without promi-
nent crystals.
Of the porphyritic type some contain prominent crystals of both
quartz and feldspar, and are closely related to the granitic rocks,
with which they may be connected. They may hold an important
relation to the ore bodies, but the relation can not be fully determined
without detailed investigation. Dikes of this sort occur most abund-
antly in the western portion of the field, where they may be seen in
places directly connected with the granitic rocks.
A decidedly porphyritic type, containing prominent crystals of
feldspar only, occurs near the Uncle Sam mine of Squaw Creek and
at a number of points about Bear Valley, but deposits of ore have
not been noted in their vicinity.
The most abundant dike rock is an altered variety of basalt or
metabasalt in which the feldspars usually have that ophitic arrange-
ment which characterizes diabase. It is generally not porphyritic
like the other diabasic rocks, but compact and greenish in color, espe-
cially on fresh fracture. Large areas of it occur about the Carbon-
iferous limestone from Gray Rock northward, and dikes of it cut
through the limestone, giving rise to interesting and important con-
tact deposits of ore unlike any others in the region. South and east
of Bass Mountain is a large mass of this ancient igneous rock, and
along the Sacramento River there are numerous dikes of it cutting
the older lavas.
Folding and displacement of the rocks. — The rocks of the copper
region are folded and faulted, but the extent in both cases is limited,
and varies with the kind of rock and locality. The shales, sand-
stones, and tuffs are usually soft rocks with little rigidity. They show
many sharp folds and faults, but an attempt to trace them reveals
their very local character and small extent. To determine whether
large folds and faults are present the Triassic, Carboniferous, and
Devonian limestones afford the best horizons for observation. Owing
<> their light color these rocks may be seen from a long distance in
tracing structure, and each, having its own characteristic fossils,
nay be identified with certaint}^ The general course of these rocks
o«||icross the region is nearly north and south, but in the Furnaceville
listrict, as well as about the head of Squaw Creek, the Triassic lime-
ullstone turns easterly, sending a synclinal point in the one case southwest
4 ;o Bear Mountain and in the other northwest to the head of Claiborne
12() CONTRIBUTIONS TO ECONOMIC GE3LOGY, 1902. [bull. 213.
Creek. With these exceptions there are no irregularities in distribu-
tion of the Triassic and Carboniferous limestone to indicate folding or
faulting on a large scale, although small gentle folds and faults are
common along the limestone front in each case. The Devonian
limestone is so cut by igneous rock as to afford no decisive evidence.
The geological date of the folding and faulting accompanied by
much crushing of the rocks was at the close of the Jurassic, when the
Sierra Nevada and the Klamath Mountains were formed and raised
above the ocean to initiate an epoch of vigorous erosion represented
by the unconformity between the Cretaceous and Jurassic. The
epoch of rock crushing gave rise to the shear zones which later became
the seat of circulating waters and finally the ore deposits of to-day.
AFTERTHOUGHT DISTRICT.
The Afterthought district is very small. It lies near Cow Creek,
where the copper-bearing rocks run under the later lavas from the
volcanic ridge north of Lassen Peak.
The country rock is chiefly igneous metarhyolite, and cuts Triassic
slates, with large limestones near by. The ore bodies, which are
chalcopyrite with other sulphides, as far as may be judged from sur-
face openings — the tunnels, long unused, have caved in — occur near
the contact between the two rocks without additional evidence of
contact metamorphism. The adjacent rocks show extensive iron and
copper staining. The conditions here appear to be similar to those
of Bully Hill and Iron Mountain districts, but the extensive prospect-
ing of years ago failed at that time to develop a paying mine.
Later improvements in smelting low-grade ores may have changed
the status of this property.
BULLY HILL DISTRICT.
Lor"/ inn and extent. — The Bully Hill district lies about 15 miles
directly north of the branch railroad at Bellevista. It has a length
of several miles in a direction a little east of north, and embraces not
only the openings in Bully Hill, but also those about Copper City.
Some openings on the slope of Horse Mountain might here be included,
but at present the prospects, although in the same volcanic masses,
are not sufficiently extenswe to furnish good ground for judgment.
It is especially interesting, however, to note that Horse Mountain is
the only locality in the region where native copper was found in the
comparatively fresh-looking igneous rock.
Country rocks. — The common country rocks are wholly igneous, j
generally metarhyolite, rich in porphyrinic quartz like that of Bully |
Hill, of which an analysis by Dr. E. T. Allen is given below (1). Some
of the rock is metabasalt without porphyritic quartz. This is espe-
cially the case in the Bully Hill mine, where the rock most intimately
diller.] COPPEE DEPOSITS OF REDDING REGION, CAL.
127
associated with the largest ore bodies yet discovered is basaltic in
character and particularly rich in soda, as indicated by the following
chemical analysis (2) by Dr. Allen.
Analyses of country rock of Bully Hill district.
SiCV
ALA
FeA
FeO.
MgO
CaO.
Na20
K20.
H20-
H2OH
Ti02.
Zr02
C02 .
PA-
s____
Cr203
MnO
BaO.
81.25
49.85
9.03
17.00
.63
4.02
.40
5.51
2.48
7.G5
Trace?
1.18
.25
4.78
1.82
None.
1.09
2.16
2.81
6.65
.08
.97
None.
None.
None.
None.
Trace.
.10
.35
.07
None.
None.
Trace.
None.
.05
Trace.
100. 24
99.94
.13
.03
100.11
99.91
1. Bully Hill mine 400 feet west of ore body, west end of tunnel 2.
2. Bully Hill mine east of ore body, in tunnel 3.
g through
This interesting rock (2) occurs in the form of a dike cuttii
the older igneous rocks and the Triassic slates. Much of the rock in
he mine, especially in the Copper City workings, looks like slate and is
so called by the miners. The resemblance, however, is only superficial
md results from the squeezing and shearing of the metarhyolite until
t possesses a slaty structure. The ore deposits are found in the zones
)f shearing.
The shear zones are usually of limited extent ; none have been traced
ipon the surface for over a mile. They vary in width from a few
nches to nearly a score of feet, and are either vertical or dip steeply
o the west, trending a few degrees east of north. In Bully Hill there
ppear to be three shear zones, two of which are well mineralized and
ontain valuable ore bodies. They are nearly parallel and only a few
128 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
hundred feet apart. The western one is wholly in the metarhyolite of
Bully Hill; the other, near the surface, is within the dike of meta-
basalt, and farther down follows the contact between the metabasalt
and the metarhyolite more or less regularly to a depth of about 500
feet.
The walls are sometimes sharp, but at many places are indistinct,
grading into the material of the shear zone.
Ore bodies. — The ore bodies occur very irregularly distributed in
shear zones and range in size from lenticular or sheet-like nodules less
than an inch in diameter to hundreds of feet long and up to nearly
a score of feet in thickness. The crushed rock in the shear zone is
not always mineralized, but generally it is more or less richly impreg-
nated with ores, sometimes to complete replacement. In the Copper
City workings, where these features are well displayed, the small ore
nodules are chiefly zinc blende, with small amounts of pyrite and
chalcopyrite.
One of the most important matters concerning ore bodies as they
lie in the shear zone is that their longer axis usually pitches steeply
to the north, so that when an ore body is struck the general position
is a guide to its prospecting.
Zones in large ore bodies. — Near the surface each large ore body is
naturally divided into three zones. Beginning at or near the surface
with the zone of oxidation, where the material is generally known as
gossan, it passes downward into the zone of enrichment, Avhere the
so-called black oxides of the miners occur, and finally at greater
depths into the zone of the original sulphides. These zones are often
extremely irregular, but are generally well defined.
Zone of oxidation. — The gossan of the Bully Hill ore bodies is, in
the main, porous limonite, occasionally with small caves containing
beautiful stalactites of the same mineral. It results from the altera-
tion of the pyritous ores, from which nearly everything but the iron
has been carried away by percolating waters, leaving the iron in the j
form of a hydrous oxide — limonite. The gossan usually contains also
a larger portion of the gold of the original ores, but the copper is
mostly carried down to form rich sulphides in the next zone. It may
combine with carbon dioxide and give rise to the green and blue car-
bonates of copper, or be reduced and native copper result. All of
these ores and also native silver occur locally in the lower part of thel
gossan or upon the borders of the Bully Hill ore bodies at greater!
depths. The red oxide (cuprite) rarely occurs at Bully Hill, but,
according to Mr. Oxam, the mine superintendent, a mass several feeti
in diameter was found in clay 6 feet from the ore body at a depth of
151 feet. The bottom of the gossan is very irregular, extending fan
down into the ore bodies along fissures favoring oxidation. On gentle
slopes it usually extends 70 or 80 feet below the surface, and some- 1
times much deeper, but upon steep slopes the gossan may be nearly
dilleb] COPPER DEPOSITS OF REDDING REGION, CAL. 129
all washed away and the original sulphides be near the surface. The
gold from the gossan washed away in past ages accumulated in Town
Creek and afforded the rich placer mines of the early days.
Zone of enrichment. — Next below the gossan occur the dark ores
which the miners usually designate " black oxide," but in reality they
appear to be chiefly dark sulphides, chalcocite, and sphalerite, gen-
erally mixed with pyrite, chalcopyrite, and barite. In some places
there is only a thin film of this material between the gossan and the
yellow sulphides, but generally in the Bully Hill district it extends
for 10 feet or more to the predominantly yellowish sulphides. Chal-
cocite is most abundant near the borders of the pyritous ore mass,
and small nodules of it are found in the adjacent fissile clays at much
greater depths. Bornite occurs locally near the gossan with black
sulphides; also at greater depths with chalcopyrite, pyrite, and sphale-
rite. While its secondary origin in the enriched zone not far beneath
the gossan is evident, that at greater depths is more doubtful.
Fresh chalcopyrite was found in the zone of enrichment incrusting
secondary chalcocite ; hence it is evident that some of the chalcopy-
rite must be secondary. The lower limit of the zone of enrichment
is not sharply defined, and it will be discovered only by detailed
investigations.
Zone of primary sulphides. — The workings in the Bully Hill mine
in October, 1902, had attained a depth of about 512 feet, which is
considerably below the lowest level where the writer saw any of the
secondary ores.
However, some of the miners report local "black oxides" at that
depth. The ore in this zone is chiefly pyrite, with some chalcopyrite
and a varying amount of sphalerite.
Gang ue. — The gangue mineral of a large part of the Bully Hill ore
is barite. It is rarely abundant, and often is so finely disseminated
as to be invisible in the ore, yet greatly increases its weight. The
source of the barite is most likely to be found in the metarhyolite,
whose feldspar appears to contain a notable amount of barium.
Selvage. — On the east wall there is generally a white selvage-like
material which ranges from a mere film to 12 feet in thickness. A
hemical examination by George Steiger shows it to contain Na20 20,
K20 3.28, and H20 11.87, from which it appears to be a mixture of
I J (kaolin and sericite. It affords an excellent material for lining the
converters. This white selvage is sometimes found on both sides of
jhe ore, and, combining, cuts off the ore. The selvage may be wholly
bsent, in which case the ore is directly attached to the wall rock.
he wall rock of metarhyolite on the west side is usually much fresher
han that opposite, and shows the hard, knotted, flinty character of
nil |ihe surface.
.ml Prospecting. — It is evident that gossan, and to some extent also the
;ii.j peculiar knotted or brecciated metarhyolite, is to be the main guide
Bull. 213—03 9
130 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
in prospecting about Bully Hill and the great volcanic belt extending
north to Bollibokka Mountain. Prominent limonite deposits from
iron springs strongly suggesting gossan beneath were seen at several
points a short distance northeast of Bully Hill, on the area of Triassic
slates. The slates along the contact with the volcanics are in places
richly impregnated with pyrite, but thus far no mines have been
opened. This field is well worthy of careful prospecting and is now
receiving attention, for recently much work has been done on some
claims near Bollibokka Mountain.
BLACK DIAMOND DISTRICT.
The Black Diamond mine, which was practically closed in 1002
except for a small amount of prospecting, is about 20 miles northeast
of Redding. It furnishes an excellent example of ore deposits on or
near the contact between limestone and diabase. The relations of
the deposits in this district differ widely from those of the other dis-
tricts. The limestone and associated sediments are well characterized
by fossils of Carboniferous age.
Small masses of pyrrhotitea and chalcopyrite occur, also pyrite and
magnetite with limonite and other secondaiy minerals. The ore is
associated with coarsely crystalline green fibrous pyroxene and gar-
net, whose relations are not so easily perceived in the mine workings
underground, but upon the surface are illustrated at many points in
the neighborhood along contacts of diabase dikes which cut the lime-
stone. The best exposures are upon the crest of the limestone ridge,
where it is crosscut by a number of diabase dikes running east and
west and ranging from 5 to 100 feet in width. Along the edges of
these dikes in contact with the limestone at many points pits have been
dug into the iron-stained fibrous masses of pyroxene mixed occasionally
with garnet, serpentine, and traces of ores. The fibers of pj7roxene
several inches in length are perpendicular to the contact and are
conspicuous. Numerous open cuts and tunnels have been made in
connection with the Black Diamond and Roseman group of mines.
All were not examined, but as far as seen the relations were all
essentially the same as described above.
The dike rock in question, here designated diabase, is composed
largely of calcic feldspar, which generally has the ophitic arrange-
ment characteristic of diabase, and incloses chlorite, epidote, magne-
tite, and quartz resulting from the alteration of feldspar and pyrox-
enes. The amount of quartz varies, and in some cases it seems a
primary constituent.
These contact deposits have been exploited chiefly about Grey
Rock, and to a less extent north of Pit River, where work is now
progressing in an open cut, iron ore being taken out for flux at the
Bully Hill smelter. The mass of magnetite incrusted by limonite is
"The pyrrhotite was examined for nickel, but there is none present.
DiLLEu.l COPPER DEPOSITS OF REDDING REGION, CAL. 131
large, and what it may lead to below is an interesting question.
Associated with the magnetite are streaks of yellowish- green garnet
and possibly also some pyroxenes, indicating that this mass of mag-
netite is a contact phenomenon.
IRON MOUNTAIN DISTRICT.
The largest and most important district of the copper region, as
far as known at present, lies west of the Sacramento River and
extends from Iron Mountain northeast for about 25 miles to the Sum-
mit mine northwest of Kennett. Only one mine in the district, that
of the Mountain Copper Company at Iron Mountain, is productive,
although there are a number of others — for example, the Shasta King
and the Mammoth — that are not only extensively developed, but
rapidly approaching the productive stage.
Iron Mountain mine. — The Iron Mountain ore bodies are marked
upon the surface by the most prominent gossan of that region. It is
chiefly limonite, which in the early days was mined for gold and
silver. In places the porous gossan extends to a depth of over 100
feet, changing abruptly from the oxides to the sulphides, but upon
the steep slopes bordering the canyons the gossan has been denuded
and the bodies of sulphides lie near the surface.
In the Iron Mountain vicinity there are two principal bodies of ore;
one, the Iron Mountain, which has been large^ mined, is said to have
been about 800 feet long, 100 to 400 feet wide, and traced to a depth
of r>00 feet. The other ore body, the Hornet, has a greater length,
but less width, and has been thoroughly prospected.
The wall rock on both sides is metarhyolite, which, according to
Dr. W. F. Hillebrand's partial analysis, contains 5.16 per cent Na20
and only 0.40 per cent K20, with 0.015 per cent BaO and 74.52 per
cent Si02. It is somewhat remarkable for containing so much more
soda than potash, and appears to be related to the soda rhyolites
described by Dr. Palache near Berkeley, Cal.
The shear zones containing the ores strike nearly northeast and
southwest, dipping vertically or steeply co the northwest. The ore
bodies are elongated, flattened, lenticular in shape, and at least in
some cases pitch in the shear zone to the northeast.
The ores where seen in the Hornet were wholly sulphides, with the
[Copper as chalcopyrite intimately mixed with pyrite. Chalcocite, so
common in the dark ore at Bully Hill, was not seen in the Hornet
| body. Sphalerite is present and occasionally forms streaks through
the pyritous ores, giving the mass a decidedly schistose structure.
j Whether this structure is derived from the schist which the ore is
supposed to have replaced, or originated in the ore during or after its
(deposition, could not be determined without more detailed investiga-
tion. Wherever the schistose structure was observed it was generally
[parallel to that of the adjacent schistose igneous rock, but some of
132 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
the small nodules inclosed in well-defined schistose structure show no
trace of it internally. Quartz is often present in the ore, but barite,
so common at Bully Hill, is absent in the Iron Mountain district.
The ore bodies usually separate easily from the wall rock, and at
many points there are considerable masses of sericite selvage, but
none so large as in the Bully Hill mine. The ore bodies are cut by
small transverse faults, and, as pointed out by Mr. Lewis T. Wright,
the general manager of the Mountain Copper Company, the sides of
the ore bodies are occasionally polished by movement since the ore
was deposited.
Balaklola and Shasta King. — Northeast of Iron Mountain, in the
same district, there are many claims more or less extensively pros-
pected, among which may be mentioned the Sugar Loaf, King Copper,
Spread Eagle, and Balaklala; but it is not until Shasta King, on Squaw
Creek, is reached that extensive activity is found. The Trinity
Copper Company, Mr. A. H. Brown, general manager, controls the
Shasta King, Uncle Sam, and numerous other claims in the neighbor-
hood, and is cautiously developing them. The ores at the northern
end of the district are in general not so rich as those of Iron Moun-
tain and need to be handled under the most favorable conditions.
SI last a King is north of and below Balaklala, which is on the oppo-
site side of Squaw Creek, and it seems probable that their ore bodies
lie in the same shear zone. The country rocks in both places may be
most appropriately designated metarhyolite. At Balaklala a large
pyritous bod}* of ore lies a short distance beneath the slope. It has
the general strike of the district and dips to the northwest nearly par-
allel to the slope. Although much gossan occurs in the region, the
slopes are usually so steep that it has been removed, and the dark
sulphides form a very thin layer between the gossan and the pyritous
ore.
In the Shasta King the ore body lies nearly flat and at its western
end above is firmly united — "frozen" — to the country rock. This is
exceptional in the copper region and even about the same ore body,
for along its eastern border it has a well-defined selvage ranging from
a mere film to a foot in thickness.
Beyond Squaw Creek the Mammoth mine and the Summit, on Little
Backbone Creek, are near the northern limit of the district.
Detailed maps on a larger scale than that of the folio publication,
which is only 2 miles to the inch, are now being made, preparatory to
a special detailed study of these mining districts.
COPPER DEPOSITS AT CLIFTON, ARIZ.
By Waldemar Lindgren.
FIELD WORK.
The study of the copper deposits at Clifton was begun in October,
1901, and finished five months later, in May, 1902. During the exam-
ination I was assisted by Mr. J. M. Boutwell. The results of the
investigation are expected to be published in the form of a profes-
sional paper. As yet, however, the necessary office work, including
the examination of the ores and minerals, is not finished, and the
following resume is therefore to be considered only as a preliminary
statement, which may be modified in some respects in the final report.
PRODUCTION AND DEVELOPMENT.
The Clifton mines were discovered in LS72, but owing to adverse
conditions, principally the absence of railroad communication, the
district did not attain prominence for a number of years. During late
years the production lias been increasing steadily and rapidly, due prin-
cipally to the discovery of very large bodies of low-grade ore adapted
to concentration. During the last eight or ten years the Clifton dis-
trict has, in point of production, ranked third among the copper dis-
tricts of Arizona, being preceded by the United Verde and by Bisbee.
The gradually increasing production amounted to 38,000,000 pounds
of copper in 1901. During that year the sequence became reversed,
Bisbee leading with 39,800,000 pounds, followed by Clifton with
38,000,000 and United Verde with 34,500,000 pounds. It is believed
that a still further increase took place in 1902, but statistics are not
yet available. It is probable, indeed, that during the year just closed
the Clifton mines produced more copper than any of the other camps
in Arizona.
The production of Arizona is at present a little more than one-fifth
of the total production of the United States.
At the present time there are three large companies at Clifton smelt-
ing copper on an extensive scale. These are : (1) The Arizona Copper
Company, having mines at Metcalf and Morenci, a few miles north-
west of Clifton, and a smelter located at Clifton. The production of
this company in 1901 was 20,500,000 pounds. (2) The Detroit Copper
Company, having mines and smelting works at Morenci. In 1901 the
133
134 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
production of this company was 17,500,000 pounds. (3) The Shannon
Copper Company, having mines at Metcalf and smelting works a
short distance below the town of Clifton. This company began oper-
ations on a large scale in 1002, and started its furnaces in the month
of May of that year.
There are a number of smaller mines and prospects, but their pro-
duction cuts a comparatively small figure.
Situated in the southeastern part of Arizona, on the north side of
the Gila River and only a few miles from the New Mexico line, Clif-
ton is connected with the Southern Pacific Railway by an independent
road leaving the main railroad line at Lordsburg, N. Mex. From a
point on the Gila River along this road a narrow-gauge railroad
branches and continues to Morenci, direct communication between
Clifton and Morenci being impracticable on account of the great dif-
ference in elevation.
TOPOGRAPHIC FEATURES.
On the north of the broad valley of Gila River lies, in this vicinity,
an irregular mountain region with no well-defined ranges. The ele-
vations in the Cila Valley are about 3,000 feet. The highest elevations
in the mountain region adjoining the valley on the north are about
8,000 feet. Rising gradually from the Gila River to the base of the
mountains is a broad terrace of detrital material, attaining at that
point elevations of about 4,500 feet. From this line, where the older
rocks emerge from the old alluvium of the Gila Valley, a steeper slope
begins, furrowed by sharply incised ravines and gulches. The Gila
River in this vicinity receives two tributaries — Eagle Creek and the
San Francisco River, both flowing southward and heading on the high
volcanic plateaus near the boundary line between Arizona and New
Mexico. These streams flow in moderately deep and sharply incised
canyons, and are evenly graded throughout their whole course, which
is generally bordered by a strip of bottom land, the width of which
rarely exceeds a few hundred feet. In their upper courses these
rivers flow through canyons cut in Tertiary lavas or older rocks,
while the lower part of the San Francisco River, at least, is cut to a
depth of about 600 feet in the old Pleistocene terraces mentioned
above as adjoining the Gila River on the north. Clifton is situated
on the San Francisco River, near the point where the older rocks
emerge from the Pleistocene terraces, and has an elevation of 3,405
feet. At Clifton the San Francisco River is joined from the west by
Chase Creek, a water course 10 miles in length and flowing in a south-
southeast direction, most of the way through a deeply cut canyon.
An irregular and high complex of mountains rises between San Fran-
cisco River and Chase Creek, the most prominent of which is Copper
King Mountain, attaining 6,825 feet. On the west side of Chase Creek
the high ridges attain elevations up to 7,400 feet, the highest point
ltndgren] COPPER DEPOSITS AT CLIFTON, ARIZ. 135
being the flat-topped mass of Coronado Mountain. The town of Met-
calf is situated on Chase Creek, 6 miles north-northwest of Clifton,
while Morenei is 4 miles distant in a northwesterly direction from
the same place, but located high up in the hills, 1,000 feet above
Chase Creek.
GEOLOGICAL FEATURES.
The old Pleistocene gravel plateau extending northward from Gila
River to near Clifton and Morenei has already been mentioned. The
older rocks rising above this plateau are to a very large extent of vol-
canic origin and of Tertiary age. The whole region north of the Gila
River for a distance of at least 100 miles, and probably much more,
is covered with very heavy flows of basalt and rhyolite. It is, in fact,
the southern edge of the great volcanic plateau of eastern Arizona.
Near Clifton original high elevation and extensive subsequent ero-
sion have combined in forming an exposure of pre-Tertiary rocks con-
sisting of granite, porphyry, quartzite, and limestone. The Clifton
area of older rocks may be considered as a small isolated mass, per-
haps 12 miles long from east to west and 8 miles broad from north to
south, appearing like an island in the surrounding vast lava flows.
The oldest rock and that which occupies the largest area is granite,
evidently of pre-Cambrian age. It forms the great mass of Coronado
Mountain and the larger part of the precipitous complex of mountains
between Chase Creek and San Francisco River.
On the somewhat irregular surface of this granite rests a sedimen-
tary series of Paleozoic age, the lower part consisting of 200 feet of
quartzite. Immediately overlying the granite is coarse quartzite con-
glomerate, in places reaching a thickness of 50 feet. This quartzite,
in which no fossils have been found, is probably of Cambrian age.
The quartzite is covered by 800 feet of limestone, the lower part of
which belongs to the Silurian system, the middle part to the Devonian,
and the upper hundred feet to the Lower Carboniferous series.
Beginning from the base, the limestones gradually become purer, and
the top stratum, well exposed at Morenei, is almost entirely pure car-
bonate of lime. Within the Devonian portion about 100 feet of clay
shale is intercalated in the limestones.
A large mass of porpl^ry, running out at various points into com-
plicated dike systems, has been intruded into these rocks, granites as
well as quartzites and limestones, and this porphyry seems most inti-
mately connected with the origin of the ore. Its character varies
somewhat. The prevailing rock near Morenei is intermediate between
a granite-porphyry and a diorite-porphyry, but at some points diorite-
porphyries of typical character also occur. The porphyry at Metcalf
is more acidic and contains large quartz crystals. It may more closely
approach a granite-porphyry, but is, geologically, probabty the same
body as the Morenei porphyry.
136 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 19D2. [bull. 213.
At the Coronado mine and other places in that vicinity small dikes
of diabase occur.
Southwest of Morenci a sedimentary series has been found which
appears to unconformably cover the Paleozoic rocks. At one place
fossils, indicating a Cretaceous age, were obtained. These rocks,
however, are only of secondary importance as far as the ore deposits
are concerned.
GEOLOGICAL STRUCTURE.
The geological structure of the pre-Tertiary rocks is rendered very
complicated by extensive faulting. In few places does this faulting
affect the covering basalt and rhyolite, from which it is to be con-
cluded that the main epoch of disturbance antedates the volcanic
eruptions of the Tertiary period. The Paleozoic era in this region was
evidently one of quiescence and deposition, and it is believed that
undisturbed deposition continued through the larger part of the Cre-
taceous period. The intrusion of porphyry took place during the
late Cretaceous or the earliest Tertiary, for we find bodies of that
rock intruded into Cretaceous sediments as well as into older rocks.
In many places this intrusion was accompanied by very great dis-
turbance, causing a fracturing and shattering of the sedimentary series
into which it was intruded. The important ore deposits were formed
during and a short time after this intrusion of porphyry. Alteration,
gradually changing and often enriching these ore deposits, has, how-
ever, continued from their deposition to the present time.
The deposition of the ores was followed by very extensive fractur-
ing and faulting, affecting, as already mentioned, all of the rocks in
the district except the younger lavas.
From the form of the remaining patches of quartzite it would seem
as if the surface of the granite and the whole overlying series had
been buckled, perhaps elevated in dome-like shape, and then frac-
tured extensively. The geological map will show the complicated
nature of this faulting. The main faults extend in an east-west or
northeast-southwest direction. Faults having a throw of over 1,000
feet are common, and in the Paleozoic series, where conditions are
favorable for deciphering the structure, as for instance near Morenci, J
the complication is particularly apparent. Among more important
faults may be mentioned that at the Coronado mine, where the south
side is dropped 1,000 feet, and that cutting across Chase Creek east
of Morenci, where again the Paleozoic series has been dropped 1,500
feet or more.
An extensive erosion, resulting in very irregular surface forms, fol-
lowed these disturbances. Then, probably in the latter part of the Ter-
tiary period, the whole region was flooded by rhyolites and basalts.
Following this, probably in the early part of the Pleistocene, the level
of the Gila River became grnatly raised by accumulations of detrital
lindqhkn] COPPER DEPOSITS AT CLIFTON, ARIZ. 137
material, and the foothills of the mountain complex were buried, up
to an elevation of 4,500 feet.
The last phase in the geological history is the present period of
erosion, which has removed large masses of these early Pleistocene
gravels and deepened the canyons and gulches to the level which they
had attained before the volcanic eruptions.
ORE DEPOSITS.
Contact-metamorphic deposits. — There is no evidence of ore deposits
having been formed in this region before the intrusion of porphyry.
This event appears to be in most intimate connection with the origin
of all the copper deposits in the region. Wherever the porphyry
came into contact with the granite or the quartzite, little alteration
is observed; but wherever we find the porphyry adjoining the lime-
stones or the shales of the Paleozoic series, very extensive contact
metamorphism is noted, resulting in the formation of large masses of
garnet and epidote. This alteration is particularly observable at
Morenci. The whole Paleozoic series is affected, but more particularly
the pure limestone of the Lower Carboniferous, which, for a distance
of several hundred feet from the contact, has been converted into an
almost solid mass of garnet. The shales have suffered less from this
metamorphism, but near the porphyry are apt to contain epidote and
other minerals. This metamorphism appears not only at the contact
of the main mass of porphyry forming the southern slope of Copper
Mountain, but also in the hills between Morenci and the Longfellow
mine, in which dikes have produced contact-metamorphic minerals
along their sides. Wherever alteration has not masked the phe-
nomena, magnetite, pyrite, chalcopyrite, and zinc blende accompany
in various proportions the contact-metamorphic minerals, and are
intergrown witli them in such a way that the contact-metamorphic
origin of these ores appears be}Tond doubt. In many places the ores
have accumulated along certain horizons in the sedimentary series,
evidently more suitable than others to the processes of alteration
which produced the deposits. The origin of these contact-metamor-
phic deposits is conceived to be in the water and metallic substances
which were originally contained in the magma of the porphyry, and
which were released by decreasing pressure at the time of the intru-
sion of the rock into higher levels of the earth's crust. We may
thus speak of these deposits as contemporaneous with the cooling and
solidification of the prophyry.
As to form, the ore deposits in limestone are often irregular, but
more frequently, perhaps, assume a tabular shape, due to the accu-
mulation of the minerals along certain planes of stratification.
Oxidizing waters have very greatly altered the deposits in lime-
stone. The sulphides have been converted into carbonates, and mala-
chite and azurite are the most common ores. Cuprite also occurs
138 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
extensively, and seems to form by preference in the shale forming
part of the Devonian system. Chalcocite and other sulphides are
almost entirely absent. The zinc blende has been carried away as
sulphate of zinc, which is frequently found in efflorescence on the
walls of the tunnels. The magnetite and the garnet which originally
formed a part of these deposits have also undergone decomposition,
the resulting minerals being silica and limonite.
The celebrated Longfellow mine is worked on one of these deposits
occurring as, roughly speaking, a funnel-shaped mass in the Lower
Silurian limestone, between two large porphyry dikes. Going farther
west along the main porphyry contact, the Montezuma is encountered,
and farther on the Detroit and the Manganese Blue mines. Both of
the latter mines were worked on several tabular ore bodies, three
or more in number, occurring in horizons varying from Silurian to
the Lower Carboniferous. All of these deposits arc now largely
exhausted. They contained a large quantity of very rich carbonate
and oxide ore. The extent of these ore bodies was, however, much
smaller than the large masses of chalcocite ore which now forms the
main support of the camp.
At Metcalf the Shannon mine contains several ore bodies of similar
origin. A fragment of the Paleozoic series outcrops on Shannon Hill,
and is cut b}r an extensive system of porphyry dikes, which in the
lower part of the mountain join the main part of a large intrusive
body of porphyry. In several horizons the limestones are greatly
altered, the final product general^ being copper carbonates and
limonite, with some quartz. In some places the ore bodies are less
affected by oxidation, and their original character of garnet, epidote,
magnetite, and sulphides may be plainly seen.
Oxidation by surface waters, as at Shannon mine, also diffused
much copper as chalcocite in some of the porphyry dikes, and the
Metcalf mine on a lower spur of the same hill consists chiefly of a
body of extremely decomposed porphyry containing chalcocite and
carbonates. Very probably this copper has migrated into the decom-
posing porphyry from bodies of contact-metamorphic rock at higher
elevation, parts of which are probably now eroded.
Fissure reins. — At many places in the district the copper deposits
consist of fissure veins, cutting alike porphyry, granite, and sedi-
mentary rocks. From the available evidence it would seem as if
these veins had been formed a short time after the consolidation of
porphyry. In lower levels the veins consist of pyrite, chalcopyrite, j
and zinc blende, magnetite being conspicuously absent. At the sur-
face many of the veins have been completely leached, and now show
nothing but limonite and silicified porphyry. This rule is, however,
not a general one, as, especially in porphyiy, oxidized ores are some-
times found in the outcrops of the deposits. Between the leached
croppings and the deep ores of pyrite and chalcopyrite is a more or
LiNDGHEN] COPPER DEPOSITS AT CLIETON, ARIZ. 139
less extensive zone of chalcocite or copper glance, deposited by sec-
ondary processes on the pyrite.
The most important vein system is that which, under the general
name of the Humboldt vein, extends from northeast to southwest
through Copper Mountain at Morenci. The outcrops of this vein are
practically barren, but at the depth of about 200 feet the deposit
becomes productive and contains chalcocite associated with pyrite.
There are usually one or more central seams of massive chalcocite,
some of which are fairly persistent. These seams are ordinarily
adjoined by decomposed porphyry, now chiefly consisting of sericite
and quartz, together with pyrite and chalcocite. These extensive
impregnations of the country rock are rarely confined by distinct
walls, but gradually fade into the surrounding porphyry. That
these deposits are genetically connected with fissure veins can, how-
ever, not be doubted. In lower levels the ore is apt to change to
pyrite and chalcopyrite. Both the Arizona Copper Company and the
Detroit Copper Company are now working the low-grade bodies of
chalcocite ore accompanying the veins. The reserves thus far opened
assure a high production for many years to come.
Parallel veins, somewhat narrower, but similar in character, are
those opened by the Arizona Central mine, also at Morenci. These
veins are partly in porphyry, partly in contact metamorphosed lime-
stone. While malachite and azurite sometimes occur, they are by no
means as prominent as in the limestone deposits, and frequently the
leached surface zone is immediately adjoined by the chalcocite ore.
The Coronado mine represents a different type of deposits. It is
formed on a fault fissure between granite and quartzite, indicating a
throw of at least 1,000 feet. The fissure is followed in places by
a diabase dike, showing some effect of crushing and movement on
the vein. The croppings contain copper carbonates and silicate, but
these minerals change at slight depth to chalcocite, and still farther
| down it is believed that the ore bodies consist chiefly of pyrite and
chalcopyrite.
Somewhat different again are the fissure veins on Markeen and
Copper King mountains. The granite of this complex of hills is cut
by a great number of porphyry dikes which generally have a north-
easterly direction. Along many of these dikes movement and As-
suring has taken place, and varying amounts of copper ores have
been encountered. The veins contain comparatively little gangue,
the copper minerals being chiefly distributed through the altered por-
phyry or through the granite adjoining the dike. At the surface a
small amount of carbonates may be found, but they change at slight
depth, sometimes only a few feet from the surface, into an ore com-
posed of chalcocite and pyrite, which still farther down appears to
change into pyrite and chalcopyrite. The most prominent deposit on
this system of veins is the Copper King mine, which is situated only
140 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [BULL.2li
a few hundred feet below the summit of the mountain of the same
name. The main mass of porphyry between Morenci and Metcalf
shows evidence of very strong mineralization throughout. A great
number of fissure veins have been encountered in it, although most
of them are neither persistent nor strong. Close to the surface the
ores are apt to spread through a considerable mass of rock, and in
some cases important bodies of chalcocite, due to secondary deposi-
tion on pyrite from solutions containing copper, have resulted.
The granite adjoining this porphyry is sometimes also thoroughly
altered and impregnated with pyrite and chalcopyrite. This may
be seen in the narrow canyons of Chase Creek for a mile above Long-
fellow Incline. While a number of more or less well-defined veins
have been opened here, the results have not been encouraging.
GOLD DEPOSITS.
The gravels lying in front of the older rocks at Morenci and Clifton
are sometimes gold bearing, though ordinarily the metal occurs in
very fine distribution. The bench gravels above Clifton, along the
San Francisco River, contain gold, and attempts have been made to
work them. The results, however, have not been encouraging. This
gold is probably derived from a system of veins cropping on thj
Dorsey and Colorado gulch, a few miles north of Clifton on the wesj
side of the San Francisco River. The system of dikes mentioned
above as cutting Copper King Mountain continues in places still fail
ther in a northeasterly direction, but the ore here contains less copper
and more gold and silver. Attempts to mine these gold-bearing veins
have not thus far been attended with much success.
Another gold-bearing district is that of Gold Gulch, 2 or 3 miles
west of Morenci. The diorite-porphyry which occurs here contains
many inclusions and fragments of limestone, and this complex
geological formation is again cut by many faults. Native gold accom-
panied by limonite and other products of decomposition has been
found in many small veins in this district, but the tenor of the ore
seems very capricious, and the deposits have not yet been proved to
be of much value.
The copper ores of Morenci and Metcalf, whether occurring as
contact-metamorphic deposits or as fissure veins, contain a very small
quantity of gold and silver, in most cases amounting to little more
than a trace. At the Copper King mine, however, in the system of
fiesure veins following dikes of porphyry and granite, a notable
amount of gold is found, and from here on northeasterly, as noted
above, this tenor in gold increases considerably.
COPPER DEPOSITS OF THE MOUNT WRANGELL REGION, ALASKA.
By Walter C. Mendenhall and Frank C. Schrader.
GEOGRAPHY AND EXPLORATIONS.
Near the southeast corner of the mainland mass of Alaska, very
near the intersection of parallel 62° north latitude -and meridian 144°
west longitude, stands Mount Wrangell, 14,000 feet high, an active
volcano, and in many respects the most impressive, although not the
highest, peak of the group to which its name is given. This group, a
complex pile of volcanic material, with half a dozen or more great
summits over 12,000 feet in height, occupies the angle between two
diverging branches of the St. Elias Range.
The drainage of a part of its northern and of all its western and
southern slopes is carried to the Pacific by the Copper River, while
White River and the two main branches of the Tanana, called the
Nabesna and the Chisana, rise on the north slope east of the Copper
and flow by way of the Yukon into Bering Sea.
In the drainage basins of the upper portions of these streams, on
both sides of the range, it has been known for many years that native
copper exists. Yukon and White River Indians used it in the interior
in the earlier days for knives and bullets, and Copper River natives
exhibited similar specimens at the coastal trading stations long ago.
Lieutenant Allen in 1885 secured specimens of bornite from Chief
Nicolai at Taral, but most of the knowledge possessed by white men
concerning these occurrences has been secured since 1898, when they
first entered the region in force. Since then prospectors have explored
rather thoroughly the southern field, which includes the basins of the
Chitina and the Kotsina, large eastern branches of Copper River.
As a result of this exploration, they have located maii}^ claims in this
region and have done a little development work. At the same time
somewhat less thorough prospecting has been carried on in the more
distant and less accessible region north of the Wrangell Mountains,
but thus far the search for promising copper deposits has been less
successful there.
In 1801 Dr. C. Willard Hayes,a while en route with Lieut. Frederick
Schwatka from Fort Selkirk to the coast at the mouth of Copper River,
visited the Kletsan Creek deposits on the upper White River. In
o An expedition through the Yukon district: Nat. Geog. Mag., Vol. IV., pp. 117-162.
141
142 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
1899 the same locality was visited and described in some detail by
Mr. Alfred H. Brooks, a of the Geological Survey, while en route from
Pyramid Harbor to Eagle City with Mr. W. J. Peters. In addition to
the Kletsan Creek occurrences Mr. Brooks gives notes on the exten-
sion of the copper belt toward the west.
In 1900 Messrs. Schrader and Spencer b visited the southern field
and issued a comprehensive report on its geology and mineral
resources, particular attention being given to the copper occurrences.
In 1902, while Mr. W. C. Mendenhall extended the earlier work of
Messrs. Schrader and Spencer in the western portion of the southern
field, Mr. F. C. Schrader visited the region about the head of the
Copper, the Nabesna, and the Chisana rivers. The results of all these
studies, with such information as can be gleaned from other sources
concerning the localities which the geologists have not visited, will
shortly be issued as a paper on the mineral resources of the Mount
Wrangell district, and for a full account of what is at present known
on the subject this report should be consulted. Only that portion of
it which bears upon the copper occurrences is summarized here.
SOUTHERN DISTRICT.
This, the best known and probably the richest of the two copper
belts of the region, occupies a strip nearly LOO miles long and of vary-
ing width along the southern base of the Wrangell Mountains.
Throughout this zone, in the drainage basins of the Chitina, the Kot-
sina, ami the Cheshnina there are scattered deposits of copper ores,
some of them very promising.
GEOLOGY/
The lowest si rat igraphically, and therefore the oldest, of the econom-
ically important formations of this belt, is a great series of successive
basalt flows, now somewhat altered, which has been called the Nicolai
greenstone. A thickness of not less than 4,000 feet of this basalt is
exposed near the western part of the area in which it is known, and
its maximum may be very much greater, as the base of the formation
is nowhere exposed. The thin sheets in which this fluid lava issued
now lend themselves to the determination of structure in the forma-
tion almost as well as does bedding in sedimentary rocks.
After the close of the period of great volcanic activity of which the
Nicolai greenstone is the record an era of sedimentation set in, appar-
ently without any intervening erosion. The first of the sediments
deposited was a massive white limestone, which is particularly promi-
nent along the Chitistone River and has therefore been called the
«A reconnaissance from Pyramid Harbor to Eagle City, Alaska: Twenty-First Ann. Rept.
U. S. Geol. Survey, Pt. II, 1900, p. 377 et seq.
b Geology and mineral resources of a portion of the Copper River district, Alaska. Special
publication of tbe U. S. Geol. Survey, 1901.
cThis account of the geology is summarized from the report of Schrader and Spencer.
iNDENHALL,-, -, . 0
and COPPER DEPOSITS OF MOUNT WRANGELL REGION. 14d
nnRATlF.H J
KENDENHALL
AND
SCHRADER.
Chitistone limestone. A series of interbedded thin limestones and
shales which carry Triassic fossils were next laid down, and these
had accumulated to a thickness of several thousand feet before the
era of sedimentation was brought to a close. Within the Chitina
Basin the massive Chitistone limestone does not carry fossils, but it
has been correlated with similar beds beyond the Scolai Range to the
north, from which Permian shells have been taken. If we accept
this evidence as determining the Permian age of the Chitistone, it
becomes highly probable that the greenstone beneath it, with no
srosional interval intervening, falls in the Carboniferous, and per-
haps in the Upper Carboniferous. A more definite conclusion than
Ibhis can not be reached with the evidence at present available.
Following the outpouring of the Nicolai lavas and the deposition of
]he succeeding calcareous terranes a period of stresses was inaugu-
rated, during which these rocks were everywhere thrown into a suc-
cession of open folds. Accompanying or following this folding the
*ocks were brought within reach of subaerial erosional agencies, and
phe folds were truncated; but the land was not, it is believed, reduced
o a plain. On the contrary, a distinct relief remained, and when the
jiext period of deposition began the sediments were laid down in local
basins and unconformably upon the truncated edges of the folds in
he older rocks. These deposits were gravels and muds, which have
:>ince consolidated into the conglomerates and shales of the Kennicott
formation. They were deposited during Jura-Cretaceous time.
i After the deposition of these gravel beds the region was again ele-
vated and folded slightly, and a period of erosion began which reduced
|he land to a generally plane surface. This plain was elevated, dis-
ected, and partly buried under the extra vasated igneous material
|\rhose accumulations have produced the peaks of the Wrangell
•fountains.
This, in brief, is the history, as at present understood, of the events
jrhich have resulted in the accumulation, burial, folding, erosion, and
iter partial reburial of the rocks which are economically important
11 the region. Of these the chief is the Nicolai greenstone. As is
ften true of greenstones in other parts of the world, this rock seems
lo have contained originally minute quantities of copper dissemi-
ated throughout its mass. During the operation of the processes to
khich the formation has since been subjected some of this dissemi-
nated copper has been concentrated at various points within the mass
Iff the greenstone or the overlying limestone, and some of these
iccumulations are of sufficient magnitude to constitute workable cop-
er deposits.
[ A plane which has seemed to be a favorite locus for these accumu-
lations is the contact between the greenstone and the overlying
limestone. Nearly all of the prominent ore bodies are on or near
iris plane, sometimes in the greenstone just below it, sometimes,
144 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
but more rarely, in the limestone just above it, and occasionally in
fissures which cross it.
The ore bodies have assumed various forms, and for convenience
of discussion these forms have been divided into two general classes,
vein deposits and bunch deposits.
The vein deposits are so defined as to include all tabular ore masses,
whether in true fissures or along joint or fault planes or shear zones.
The ores may be found only in shoots within the planes which have
controlled their form, but are characteristically of indefinite extent
in one or two directions.
The "bunch" deposits, on the other hand, are irregularly bounded
masses of ore, from a few inches to a few feet in diameter, which
usually are not obviously related to fractures or fissures or joint
planes, but in form are much like basic segregations in igneous
rocks — i. e., they generally have indefinite limits, grading from
masses of practically pure ore at the center through leaner and leaner
phases, into the entirely unmineralized inclosing country rock.
These "bunches" are so numerous in certain parts of the field within
the upper part of the greenstone that prospectors who have opened a
number of them, 400 or 500 feet below the base of the limestone, have
been led to conclude that a ledge of ore parallels the contact at this
horizon.
MIXES AND CLAIMS.
In order to give an idea of the different types of deposits and the
conditions of development, some of the best-known occurrences will
now be described.
Nicolai mine. — The Nicolai mine is located near the eastern part of
the Chitina copper district, on Nicolai Creek, a few miles west of the
Nizina River. The vein, a fissure with definite walls, is in the green-
stone not more than 50 feet below the base of the limestone. It
trends about N. 50° E. and dips 75° SE., and a displacement of not
more than 50 feet has taken place along it. The main fissure, which
may be traced for several thousand feet, although it shows no
ore except near the place of discovery, is paralleled at distances of
90 and 140 feet by two other fissures, which also contain copper min-
erals. In the vicinity of a shaft which has been sunk in the process
of development, the vein has a width of from 8 to 12 feet and is about
equally divided by a horse of greenstone 3 or 4 feet across. The ore
on either side of this horse is practically pure bornite with only a
small amount of quartz associated in an irregular way. Locally there
is a band of chalcopyrite lying next the hanging wall.
In 1900, when the shaft had been sunk to a depth of 30 feet, ore
from 2 to 4 feet in thickness was exposed throughout this depth.
Bonanza claim. — This claim is located upon a high ridge between
Kennicott Glacier and McCarthy Creek, and is about 8 miles west of
the Nicolai mine. This vein also is a fissure, which cuts across the
contact between the greenstone and the limestone, although for some
DENHALL-, ^ , _,
and COPPER DEPOSITS OF MOUNT WRANGELL REGION. 145
JHiDER -•
MENDENHALL
AND
SCHRADEK.
distance below the contact the vein is barren. It is irregular in
width, varying between 2 and 7 feet, and has a strike of about
N. 40° E. There is no quartz or other vein material associated with
the ore, although there is sometimes a considerable amount of crushed
limestone between the walls. The ore is practically pure chalcocite,
or copper glance, which is exposed in solid masses 2 to 4 feet across
and 15 feet or more in length. Besides the ore within the fissure
there are bedded ore bodies running off into the limestone along the
planes of stratification. The ore is regarded as a replacement of the
limestone. A selected sample gave over 70 per cent copper and 14
ounces of silver per ton, with a trace of gold.
Louise claim, Elliott Creek. — Elliott Creek is a tributary of the Kot-
sina River and is near the western end of the copper area. The
Louise claim is on a small branch of Elliot Creek called Rainbow
Creek. Here, in a shallow open cut, a slickensided face of greenstone,
forming a well-defined and, so far as exposed, regular foot wall, is
revealed. This face strikes N. 10° E. ami dips 70° NW. The cut does
not expose an equally definite hanging wall, but adjacent to the foot
wall is a crushed zone, which has an extreme width of 15 or 16 feet.
Within this zone the greenstone is generally irregularly fractured,
but at the j)resent surface there exists, in the center of this crushed
mass, a "horse" of solid greenstone 7 or 8 feet wide. It is probable
that the slickensided foot wall is a fault plane, but since no displace-
ment was observed in the limestone above, its throw can not be great.
The mineralization within this belt consists of an impregnation of
chalcopyrite and bornite, the latter mineral being superficially more
abundant. The impregnation follows the fractures and partakes of
their irregularity, the exposed surfaces of the greenstone fragments
generally showing more or less ore.
Goodyear claim, Elliott Creek. — Across Rainbow Creek from the
Louise claim and a few feet below it, an open cut in greenstone reveals
a well-defined fissure vein 4 to 5 feet wide, striking N. 12° E. and
dipping 45° SW. The vein can be traced 50 or 75 feet up the slope
toward the limestone contact before it is buried under the talus.
The gangue minerals are quartz and calcite, entirely distinct from
the perfectly definite walls of greenstone, and this gangue carries
heavy bodies of bornite and a smaller quantity of chalcopyrite.
While the heavy ore bodies are confined to the vein, the shattered
hanging wall and the more massive foot wall are impregnated with
copper sulphides for some distance above and below.
In the upper part of the open cut a slight horizontal fault has dis-
placed the vein laterally, so that the hanging wall above the displace-
ment is continuous with the foot wall below it.
Eleanor, Davy, and associated claims, Kotsina River. — Two thou-
sand five hundred feet above the level of the Upper Kotsina River,
near the crest of a sharp ridge separating two tributaries, Peacock
Bull. 213—03 10
146 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
Creek and Roaring Gulch, a number of claims have been staked in that
belt in the greenstone, a few hundred feet below the limestone, which
seems everywhere to carry ' ' bunches " of copper ore. No development
work has been done here, but the exposures on the faces of the green-
stone cliffs show small ore bodies from a few inches to 2 or 3 feet in
diameter and irregular in outline. They usually have cores of nearly
pure bornite or chalcocite, but marginally these copper minerals
become mingled with the surrounding greenstone as though the
replacement had been less complete on the borders of the mass.
In one or two instances narrow fissures from one-half inch to 1-J
inches wide were noted which extend downward from ore pockets
and are themselves filled with copper sulphides, but in the majority
of cases no such connection between pocket and veinlet is to be seen.
The most of the copper in the district is in the form of the sulphides,
bornite, chalcocite, and chalcopyrite, but native copper also is known.
A bowlder of the latter weighing several tons has been found in the
gravels of Nugget Gulch, a tributary of the Kuskulana River, near
the western end of the area; and on the upper Kotsina River several
claims in which native copper occurs associated with other ores have
been staked in the greenstone 4,000 or 5,000 feet below the contact
witli the limestone. Two of these, the Keystone and the Copper
King claims, are described here.
Keystone claim. — Two short forks, both glacial streams, unite to
form Kotsina River. The southern one of these drains two glaciers,
and in a little narrow post-Glacial gorge just below the foot of the
northernmost of these glaciers is the Keystone claim. Here in the
wall of the canj^on, in the greenstone, are some compact quartz
stringers and lenses, varying in width from a mere line to 5 or 6
inches. They strike east and west and are approximately vertical.
Epidote is associated with the quartz, sometimes in equal amount,
as a gangue mineral in the veins. Native copper occurs in the epidote
and in the quartz, but is more abundant in later irregular crevices
traversing both minerals of the gangue. A small amount of chalcocite
is present also, and in one prominent example it fills a narrow fissure
which intersects masses of both epidote and quartz and is evidently
later than either.
Copper King claim. — This prospect is situated on the north side of
the Kotsina Valley about one-fourth mile west of the Keystone claim
and 700 or 800 feet above the river level. It consists of an altered
belt of greenstone, in part amygdaloidal, extending several feet east
from a well-defined north-south vertical crevice, along which there
has probably been some movement. The greenstone within this
altered zone has been rendered quartzose, the quartz occurring as
si ringers and as a filling of the amygdules. The septa between the
latter are sometimes changed to granular epidote and chlorite.
Native copper occurs here and there in the mass in grains and
and COPPER DEPOSITS OF MOUNT- WRANGELL REGION. 147
MENDENHALL
AND
SCHRADER
flakes, sometimes intimately associated with chaleocite. The latter
mineral occurs with the native copper and in minute crevices which
seem to be later than the general alteration and silicification.
NORTHERN DISTRICT.
North of the volcanic pile of the Wrangell Mountains, in the valleys
of the Copper, of the two forks of the Tanana River, called the
Nabesna and the Chisana, and of the White River, native copper has
been reported from time to time, and the reports have been substan-
tiated by prospectors and others who have brought out nuggets of
the metal.
GEOLOGY.
The geologic conditions under which the copper occurs in the
northern district are different from those which prevail in the Chitina
Basin. Although the Nicolai greenstone, which is the great copper
reservoir for the southern field, is probabty present, it does not play
the important part that it does south of the mountains.
A great calcareous series, which is believed to be equivalent to the
Chitistone limestone, is clearly recognized over a large area. It has
been affected by complex structures in the northern as in the southern
district, and after its deformation and erosion Mesozoic beds have
been deposited unconformably upon its edges, and the still later lavas
of Mount Wrangell have buried many of its outcrops. In these
respects its history is similar to that of the equivalent beds to the
south. The essential difference, however, is in its relation to the
basic igneous rocks. Instead of being clearly deposited conformably
upon the surfaces of earlier flows, it has been extensively cut by later
intrusives, and the contacts with these diabases, which are altered in
many cases to greenstones, seem to be the loci for the accumulation
of native copper and other copper ores. One occurrence, of no
economic importance, is known in an altered mass of diorite.
OCCURRENCES OF COPPER ORE.
The evidence at present available, although incomplete, is better
than that upon which earlier judgments were based. It does not indi-
cate that these northern occurrences have much commercial value.
A brief description of some of them follows:
Monte Cristo Creek and California Gulch are respectively western
and eastern tributaries of the Nabesna River, which they join within
3 or 4 miles of the foot of the glacier. A mass of altered diorite
occurs in this region, and along the lines of fracture in this diorite
there occur sporadically films and blotches of malachite, which is prob-
ably derived from a little chalcopyrite contained in the altered rock.
In the mountains just east of California Gulch fragments of low-
w grade copper ore, consisting essentially of pyrrhotite and copper
148 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
pyrite, are found in the gulches. These are of such size as to indicate
that the ore bodies from which they came must be at least 6 inches
wide. The ore is of so low grade, however, assaying but six-tenths
of 1 per cent, that the deposit is without value. This ore is supposed
to be related to an intrusive contact between the greenstone and the
limestone about the heads of the gullies in which the ore is found.
On Camp Creek, an eastern tributary of the Nabesna, about 15
miles below the glacier and about 3 miles above the mouth of Cooper
Creek, Mr. Alfred B. lies reports a vein of chalcocite from (5 inches to
2 feet in thickness. Both the limestone and the greenstone are pres-
ent in this region, and it is probable that the ore occurs in association
with them.
Natives living on the Chisana (Upper Tanana) in 1002 had in then-
possession a number of small copper nuggets, and one mass which
weighs 35 to 40 pounds. These, they say, came from a small creek
which (lows into the Chisana from the west at a point about 5 or G
miles above the foot of the glacier. Occasionally the nuggets have
adhering to them fragments of amygdaloidal greenstone and of calcite
gangue. It is likely that they occur in the usual way, in association
with the contact of the diabase and the Permian limestone.
Prospectors, among whom may be mentioned Mr. D. K. Van Cleef,
report the finding of numerous copper nuggets along the north base
of the Nutzotin Mountains between the Upper White and the Chisana.
Mr. Van Cleef reports also the probable existence of a sulphide vein
in a canyon of 1 he middle White.
Kletsan Creek, which drains the north base of Mount Natazhat,
is a southern tributary of Upper White River. Native copper in
placer form has been known in this region since Dr. Hayes a visited
it in 1891, and it was probably a source of supply for the Indians long-
before that. Mr. Alfred II. Brooks b in 1899 reported one nugget 8 or
10 pounds in weight, and numerous other smaller pieces from this
locality. In a search for the origin of the nuggets, Mr. Brooks found
stringers of the native metal occurring in calcite veins in dioritic
greenstones near the intrusive contact of the greenstone with Per-
mian limestone. No other minerals except a superficial staining by
malachite were observed. The character of the bed-rock geology and
the finding of native copper in stream gravels led Mr. Brooks to infer
that conditions similar to those at Kletsan Creek are likely to be
found in the region between the Upper White and the Chisana.
From these meager descriptions it will be realized that the search
for valuable deposits in the field north of the Wrangell and Skolai
Mountains has not thus far revealed any large ore masses, but as the
search has been by no means exhaustive it is entirely possible that
deposits of practical importance may be found in the future.
"An expedition through the Yukon district: Nat. Geog Mag., Vol IV, pp. 117-162.
'-A reconnaissance from Pyramid Harbor to Eagle City, Alaska: Twenty-first Ann. Rept. U. S.
Geol. Survey, Pt. II, 1900, p 377 et. seq..
COPPER DEPOSITS OF BISBEE. ARIZ.
By F. L. Ransome.
INTRODUCTION.
During the autumn and winter of 1002 a detailed geological inves-
tigation was made of the Bisbee quadrangle, embracing the greater
part of the Mule Mountains, by F. L. Ransome, assisted by J. Morgan
Clements and Alfred M. Rock. The geology of the quadrangle was
mapped on a scale of approximately 1 mile to the inch, Avhile an area
of 8 square miles in the immediate vicinity of the principal mines was
mapped geologically on a scale of 1,000 feet to the inch. The material
gathered during the progress of the field work will shortly be embodied
in a full report upon the geology and ore deposits of the district. In
the meantime the following brief sketch includes only such salient
results of the unfinished investigation as seem least likely to be modi-
fied by further study.
GEOGRAPHY.
The Warren mining district, in which occur the ore bodies that
have given Bisbee its prominence, lies in the central part of the Mule
Mountains, a generally northwest-southeast range, some 30 miles in
length, extending from the old mining town of Tombstone down to
the Mexican border. In the vicinity of Bisbee the range attains an
elevation of 7,400 feet and has a width of about 12 miles; but in the
neighborhood of Tombstone and near the international boundary line
it is represented by clusters of comparatively low hills. On the south-
west the Mule Mountains are separated by the broad valley of the San
Pedro from the Huachuca Mountains, and on the northeast by the
similar wide expanse of Sulphur Spring Valley from the Swisshelm
and Chiricahua ranges. On the north a few low hills just southeast
of Tombstone connect the Mule Mountains with the Dragoon Range.
The town of Bisbee, with a population estimated at about t>,000, is
crowded into a few narrow confluent ravines in the heart of the range.
It is connected by the El Paso and Southwestern Railroad with El
Paso, with Benson on the main line of the Southern Pacific Railway,
and with Douglas and Naco on the international boundary.
GENERAL GEOLOGY.
The oldest rocks in the Mule Mountains are fine-grained sericite-
schists, derived from ancient sediments. These were probably origi-
149
150 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
nail}7 shales or arkose sandstones which were folded and metamor-
phosed into their present crystalline condition before Cambrian time.
After long erosion these schists were reduced to a surface of very
slight relief, which in Cambrian time was submerged beneath the sea
and covered with the sands that are now represented by quartzite,
from 400 to 500 feet in thickness. The submergence of the area con-
tinued, and about 750 feet of thin-bedded, cherty, fossiliferous Cam-
brian limestones accumulated on top of the quartzite. No record of
Silurian time has been discovered in the Bisbee quadrangle. Over-
lying the Cambrian limestone, apparently in perfect conformity, are
340 feet of dark-colored, compact, rather thin-bedded limestones, with
some intercalated shales, all carrying an abundant and characteristic
Devonian fauna, consisting chiefly of brachiopods and corals.
The opening of Carboniferous time was, in this region, unmarked
by any interruption of the continued subsidence. No unconformity
has been detected between the Devonian and the Lower Carbonifer-
ous (Mississippian) rocks. The latter consist of white or light-gray
granular limestones, often made up almost entirely of crinoid stems
and containing a fairly abundant brachiopod and coral fauna. The
thickness of the Lower Carboniferous limestone may be provisionally
given as 700 feet. The beds are often 6 feet or more in thickness and
commonly form cliffs overlooking slopes carved from the less resistant
Devonian and Cambrian limestones.
There is in the Mule Mountains no discoverable stratigraphic break
between the Lower and Upper Carboniferous beds. Subsidence appar-
ently continued, and the generally thinner beds of Upper Carbonifer-
ous (Pennsylvanian) limestone accumulated to a thickness of over
3,000 feet above the Lower Carboniferous. The Upper Carboniferous
limestones are usually more compact in texture than those of the
Lower Carboniferous, and are more fossiliferous. They are also some-
what more variable in color, pinkish and yellowish beds being of fre-
quent occurrence.
The local Paleozoic section from the pre-Cambrian schists very
nearly to the top of the Lower Carboniferous is well exposed on the
northeast face of the main ridge about 1J miles west of Bisbee. The
Upper Carboniferous beds are best seen in the hills just north of Naco
Junction (5 miles southwest of Bisbee), and the relation between the
lower and upper divisions is well shown near the Whitetail mine,
about 2 miles due south of Bisbee.
At some time during the interval between the close of the Carbon-
iferous and the opening of the Cretaceous the long-continued subsi-
dence and sedimentation of the region were interrupted by extensive
faulting, probably connected with uplift. Accompanying or immedi-
ately following the faulting came intrusions of granitic magma which
solidified as granite, granite-porphyry, and rhyolite-porphyry. These
intrusions took the form of dikes following fault fissures, of sills
injected between sedimentary beds, and of irregular stock-like masses.
ransome] COPPER DEPOSITS OE BISBEE, ARIZ. 151
The dikes are well shown along the southwest face of the main ridge
west of Bisbee. The larger intrusions are exemplified by the granitic
mass of Juniper Flat, which is inclosed in schists, and of the smaller
body of mineralized and altered porphyry forming Sacramento Hill,
just southeast of Bisbee, and intrusive into schists and limestone.
The latter mass is of particular significance from its connection with
the principal copper deposits of the district. The intrusion of the
porphyry was accompanied by little or no contact metamorphism even
in the limestones.
After the intrusion of the granite-porphyry the region was eroded
until the opening of Cretaceous time. It is probable that the princi-
pal mineralization of the district followed closely the eruption of the
porphyry, and thus dates from early Mesozoic time.
At the beginning of the Cretaceous the region again began to sub-
side, and a conglomerate was deposited by the advancing sea over the
eroded surface of the pre-Cambrian and Paleozoic rocks, with their
intruded masses of porplryry. In places this conglomerate was laid
down to a uniform thickness of about 75 feet over an even surface,
but elsewhere it is found filling hollows in a pre-Cretaceous hilly
topography, and attains a local thickness of 500 feet. The pebbles
are composed chiefly of schists, although those of limestone and gran-
ite-porphyry are not entirely absent. With the continued subsid-
ence of the region about 1,800 feet of unfossiliferous sandstones and
shales, with occasional lenses of sandy limestone, accumulated above
the basal conglomerate. Conformably overlying these are about 650
feet of limestone beds containing abundant fossils belonging in the
Comanche division of the Cretaceous. Most of these limestones, par-
ticular!}' the lower beds, are thin bedded and impure, but hard, gray,
massive beds, aggregating some 40 feet in thickness, occur near the
middle of the calcareous member of the local Cretaceous section, and
form a cliff that is a conspicuous topographic feature of the hills
north and east of Bisbee. The limestones are conformably over-
lain by more than 2,000 feet of sandstones and shales, much like
those occurring in the lower part of the section. These upper arena-
ceous beds are the youngest stratified rocks exposed in the Bisbee
quadrangle. As their upper surface is everywhere one of erosion,
their original thickness is unknown. The foregoing Cretaceous strata
were first described by Dumble, and by him called the " Bisbee
beds."a
The Cretaceous beds of the Bisbee quadrangle have been deformed
by folding and faulting. The folds are generally open, dips of more
than 20° being rather exceptional. The general strike is northwest
and southeast, and the prevailing dip northeast. About 7 miles
southeast of Bisbee, however, where Paleozoic beds have been thrust
by faulting over the Cretaceous, the latter have been turned up
a Trans. Am. Inst. Min. Eng., Vol. XXXI, 1902, pp. 703-706.
152 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
steeply and are in places nearly vertical. East of Bisbee the faults
are normal, but southeast of Mule Pass Gulch faults of the reversed
or overthrust type predominate. As Tertiary sediments are absent in
the Bisbee region, this period was probably marked by the deforma-
tion of the Cretaceous and older rocks and by erosion.
The Pleistocene is represented by unconsolidated gravelly deposits
flooring the broad valleys that surround the Mule Mountains on the
west, south, and east. These are in the main fluviatile wash, with
possibly some finer lacustrine beds at a distance from the mountains.
It is impossible without the aid of a geological map to do more than
indicate very crudely the general distribution and structure of the
rocks of the Bisbee quadrangle. A northwest-southeast diagonal
drawn through the quadrangle will pass through the town of Bisbee
and form a rough division between the Cretaceous beds on the north-
east and the pre-Mesozoic rocks on the southwest. The former,
although folded and faulted, exhibit simple structures and have a
prevalent dip to the northeast, away from the older rocks. They
undoubtedly once extended farther over the Paleozoic rocks to the
southwest, but have been removed by Tertiary and Pleistocene erosion.
In contrast with the Cretaceous beds, the Paleozoic and pre-Cambrian
rocks exhibit a highly complex structure, which, if we disregard the
undecipherable pre-Cambrian deformation of the crystalline schists, is
due to faulting, to intrusions of granite-porphyry, and to folding. In
the northwestern part of the quadrangle the Paleozoic beds dip gen-
erally to the southwest, but they change near Bisbee to a southeast-
erly dip, which in turn swings round to a northeasterly dip a few
miles southeast of the town. The pre-Cambrian schists, which are
extensively exposed in the northern part of the district, pass gradu-
ally beneath the Paleozoic beds to the southwest, being less and less
frequently exposed in the various fault blocks, and finally disappear-
ing altogether toward Naco Junction.
DEVELOPMENT AND PRODUCTION.
Prior to the year 1880 Bisbee was an unimportant lead camp, a
single furnace being then in operation upon cerussite mined from the
Hendricks claim, close to town. The copper ore of the Copper Queen
mine was discovered early in this year, and was profitably exploited
until 1881. This ore was free from sulphur and had an average tenor
of 23 per cent of copper. It was treated in two 36-inch furnaces,
which, in spite of their small size were able, with wood as fuel, to
turn out about half a million pounds a month. In 1882 the men com-
posing the present Copper Queen Company bought the Atlanta claim
near the original discovery and began prospecting.
In 1884 the Copper Queen ore body, which had been worked for
300 feet down an incline, was exhausted. The outlook was gloomy
and work was almost abandoned, when a second ore body was simul-
ransome.] COPPER DEPOSITS OF BISBEE, ARIZ. 153
taneously discovered from the original Copper Queen incline and
from the Atlanta workings. In order to avoid legal complications
the two companies combined as the Copper Queen Consolidated Min-
ing Company, which gradually absorbed the neighboring properties
by purchase. In 1886 the old smelting plant became inadequate and
was rebuilt. Greater economy was necessary, as the average tenor of
the ore had fallen to about 8 per cent and the price of copper had
notably declined.
Shortly after 1890 the completely oxidized ores showed signs of
failing, but in 1893 the works were remodeled by the introduction of
converters, and sulphide and oxide ores have since that time been
successfully worked together by the matte process. The introduc-
tion of these converters was due to Dr. James Douglas, and marked
the beginning of a new epoch in the smelting of copper ores in
Arizona.
Up to the end of 1902 practically all of the copper from Bisbee was
the product of the connected group of mines ow^ned by the Copper
Queen Company. Recently, however, extensive ore bodies have been
opened up in the Calumet and Arizona mine, and in the latter part of
December, 1902, this company was turning out from 30 to 40 tons of
copper a day from its new smelter at Douglas.
This town, situated in the middle of Sulphur Spring Valley, on the
international boundary, has sprung up with remarkable rapidity dur-
ing the last year. Its growth is due to the erection here of the new
smelters for the Copper Queen and the Calumet and Arizona companies,
and to the fact that it is the junction point of the newly completed
El Paso and Southwestern Railroad with the Naeosari Railroad into
Mexico. It will undoubtedly become an important smelting point,
not only for the Bisbee ores but for those from Mexico.
From August, 1880, to the end of 1902 the total output of the Cop-
per Queen Company was over 378,000,000 pounds of copper. The
production of all the other mines within this period was probably
something less than 2,000,000 pounds, so that the total production of
the district may be given, in round numbers, as 380,000,000 pounds
of copper. The maximum output was in 1901, when the Copper
Queen mines produced 39,781,333 pounds of copper.
THE ORES.
(jfeneral occurrence of the ores. — The principal bodies of copper ore
lie south of the town of Bisbee, within a radius of a mile. They occur
in Carboniferous limestone, on the southwest side of a great fault,
and closely associated with an intrusive mass of granite-porphyry.
In the absence of the geological map and sections the structural rela-
tions may perhaps be most clearly presented by a homely illustration.
If half of a broken saucer be placed on a table with the fractured
edge lying about west-northwest, and if the back of a book be laid
154 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
against this edge, we shall have a rough illustration of the geological
structure near the town of Bisbee. The saucer represents the synclinal
attitude of the Paleozoic beds from the Upper Carboniferous limestone
down to and including the Cambrian quartzite. The broken edge of
the saucer is the great fault, while the book is pre-Cambrian schist,
against which Upper Carboniferous limestone has been dropped by
this fault with a throw of more than 1,500 feet.
The town of Bisbee lies on the fault line. The hills northeast of
town are composed of pre-Cambrian schists; those just south of it
are Upper Carboniferous limestone, with Lower Carboniferous, Devo-
nian, and Cambrian beds coming successively to the surface along the
fault to the northwest.
A little less than half a mile southeast of the center of town the
fault encounters a mass of altered granite-porphyry and as a simple
fracture disappears. This porphyry, which forms Sacramento Hill, a
well-known local landmark, is a very irregular mass about a mile in
diameter. It has invaded the pre-Cambrian schists on the northeast
and the Upper Carboniferous (probably also the deeper-lying, older
Paleozoic beds) on the southwest. The available evidence indicates
that the intrusion of this porphyry took place after the dislocation of
the invaded rocks by the great fault. The latter probably continues
to the southeast of the porphyry mass, but it is concealed in this
direction by the younger Cretaceous beds. The Paleozoic beds form-
ing the faulted syncline are not merely flexed, but are cut by many
faults, some of them of considerable throw. These faults are, as far
as seen, of the normal type.
The ore occurs very irregularly as large masses within the lime-
stone. The horizontal extent of these bodies is usually much greater
than the vertical. The}^ are rudely tabular in form and lie generally
parallel to the bedding planes of the limestone. As a rule the impor-
tant ore bodies have been found within a distance of 1,000 feet of the
main porphyry mass or of the great fault fissure just northwest of the
porphyry. In the Czar workings of the Copper Queen mine, partly
under the town of Bisbee, ore bodies have been worked from the sur-
face down to a depth of about 400 feet, but toward the southeast the
bulk of the ore occurs at increasing depths. In the Calumet and Ari-
zona mine, about 3,500 feet south of the Czar, no large ore bodies were
encountered until the shaft had penetrated about 800 feet below thej
level at which the first ore bod}- was discovered on the Copper Queen
claim. The ore thus occurs at increasing depths toward the center
of the local synclinal basin. Detailed structure sections will probably;
show, however, that the upper limit of the ore increases in depth::
somewhat less rapidly than would be the case did it correspond to a
definite stratigraphic horizon.
With the exception of the extreme western part of the Copper Queen
mine, all of the productive and important workings in the vicinity of
ransomk.] COPPER DEPOSITS OF BISBEE, ARIZ. 155
Bisbee are in the Carboniferous limestones. It is probable that the
greater number of the ore bodies occur in the granular limestones of
the Lower Carboniferous, but the distinction between Upper and Lower
Carboniferous beds can rarely be satisfactorily made underground.
Some important ore bodies certainly occur in the lower part of the
Upper Carboniferous. On the other hand, no ore bodies of conse-
quence have yet been found in the deeper-lying Devonian and Cam-
brian limestones. In the Copper Queen mine local usage has distin-
guished an "upper lime " and a "lower lime." As far as could be
seen, however, this distinction is largely imaginary and is based on
no constant lithological or structural features. The "lower lime"
appears to be any limestone lying underneath the known ore bodies.
It is in the main Lower Carboniferous, and the ore-bearing possibility
of the underlying and Devonian and Cambrian beds is yet to be ascer-
tained by deeper prospecting.
Although the ore masses in general are what are generally termed
"flat" ore bodies, dipping gently with the inclosing beds, they are
related to other structures as well as bedding planes. , Ore is usually
found in large masses along the contact of the limestones with the
main porphyry mass. This contact, however, has not been thoroughly
explored, and much of the ore along it consists largely of low-grade,
partly oxidized pyrite. Dikes and sills of porphyry occur in the lime-
stones at various distances from the main intrusive mass, and the se
are almost invariably associated with ore in the adjacent limestone.
In some cases large ore bodies, followed for a long distance in the gen-
eral plane of the bedding, have been known to turn down almost ver-
tically alongside a porphyry dike. Fissures in the limestones have
also undoubtedly influenced the distribution of the ore.
While the main porphyry mass of Sacramento Hill is often heavily
impregnated with pyrite, it has not been shown to contain workable
ore bodies. It is possible that one or more of the oxidized ore bodies
in the Copper Queen mine were formed by the mineralization of the
granite-porphyry, but this is a point which the present investigation
has not yet determined. It is certain that many of the porphyry dikes
encountered in the workings of the Copper Queen mines show no
appreciable mineralization, even when in contact with ore.
Miner alogical character of the ores. — The ores worked by the Cop-
per Queen Company up to 1893 were oxidized ores, consisting chiefly
of malachite, azurite, cuprite, and native copper. In the upper
levels the malachite and azurite occurred in beautiful incrustations
and stalactites, lining caves in the limestones. These "cave ores"
have been exhausted, and although oxidized ore is still abundant it
occurs generally as soft earthy masses, often containing cuprite and
native copper, and usually associated with large amounts of limonite
and kaolin. Native copper and crystalline cuprite are still abundant
in the recently opened workings ot the Calumet and Arizona mine.
156 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
The original sulphide ores from which the oxidized ores have been
derived consist of pyrite containing variable amounts of chalcopyrite.
These pyritic ores are sometimes directly in contact with oxidized
ores, but it is not uncommon to find masses of chalcocite between the
two. Bornite has been reported from some of the ore bodies, but
arsenical or antimonial compounds are absent, so far as known.
Origin of the ores. — That the original ore deposition was genetically
connected with the intrusion of the granite-porphyry is reasonably
certain. The present incompleted investigation, however, has not yet
established the details of this connection. As a whole, the ore bodies
may be classed as typical replacement deposits in limestone.
The ore bodies that have thus far proved workable have resulted
from the operation of later processes of concentration acting upon the
original pyritic ores. The occurrence of the chalcocite is closely
related to the general progress of oxidation, and this mineral has
plainly been formed by the action of descending solutions upon lean
pyritic ores. It is probable that at least a .part of the chalcopyrite is
ascribable to the operation of the same agency. There is an observed
connection between good ore and permeability to downward-moving
solutions. Such pyritic ore as proves profitable is soft and crumbling
and usually shows upon close examination interstitial sooty material
that is probably amorphous chalcocite.
The lower limit of oxidation of the ores is very irregular, and is
apparently uncontrolled by any constant groundwater level. In the
Calumet and Arizona mine oxidized ore occurs at a depth of a thou-
sand feet, while residual masses of sulphide ore occur in the adjoining
Copper Queen mines within 150 feet of the surface. Masses of lean
pyrite are sometimes inclosed in an envelope of high-grade chalcocite
and oxidized ores.
FUTURE OF THE DISTRICT.
Although more or less mineralization occurs at many points in the
Mule Mountains, there is little to indicate that any deposits of copper
ore will ever be found to approach in importance those already known
and awaiting discovery in the faulted limestone syncline about Sacra-
mento Hill. For over twenty years the Copper Queen mine has pro-
duced an average of more than 16,000,000 pounds of copper annually.
Recentty the Calumet and Arizona Company has begun energetic
operations in ground almost surrounded by the property of the Coppei
Queen. Not onl}< is there sufficient known ore in these mines to keep
them in operation for many years to come, but there is no evidence!
that the bottom of the ore-bearing ground has been reached in any oi
these extensive workings. Moreover, the statement maybe venturer
that the specter of the "lower lime" has hitherto had an undue infiu
ence in restricting prospecting to horizontal planes. There is cer
tainly a reasonable hope of finding ore bodies in the Devonian anc
ransom k] COPPER DEPOSITS OF BISBEE, ARIZ. 157
Cambrian limestones beneath the masses that have been so profitably
worked in the overlying Carboniferous beds.
But more than this, it may be pointed out that less than half of the
semicircular mineralized zone about the porphyry mass of Sacramento
Hill has been explored at all. Ore was first discovered at the surface
on Queen Hill, at the northwest end of the zone. From this discover}7
'developments have been pushed by underground exploration, often
with little or no surface showing, to the south. There still remains,
however, an extensive area of unknown but promising ground, lying
just south of Sacramento Hill and extending eastward toward the south-
eastern continuation of the great fault, which is here concealed by the
ibasal conglomerate of the Cretaceous series. This is the eastern half of
jthe semicircular mineralized girdle about the intrusive mass of por-
phyry. Its exploration calls for no greater outlay or boldness than is
already displayed in other parts of the district with less assured hope
3f reward.
In conclusion, it ma}7 be said that Bisbee is less likely to suffer from
■a lack of ore than from too rapid exhaustion of the high-grade oxidized
ores which are necessary for the economic smelting by present pro-
issses of low-grade sulphides.
MINERAL RESOURCES OF THE ENCAMPMENT COPPER REGION,
WYOMING.
By Arthur C. Spencer.
INTRODUCTION.
The town of Encampment is situated 43 miles by wagon road south
of Wolcott station on the Union Pacific Railroad, in Carbon County,
Wyo., in the foothills of the Park Range, which constitutes the conti-
nental divide and is localty known as the Sierra Madre.
The Encampment Special quadrangle occupies the area between
latitudes 41° and 41° 15' north and longitudes 106° 15' and 107° 15'
west, and includes the town of Encampment in its northeast corner.
The greater portion of the area, which has an extent of about 450
square miles, lies within the State of Wyoming, but a narrow strip of
Colorado is included upon the south.
In a more extended report now in preparation a statement of the
several classes of ore deposits observed will be given, together with a
general discussion of the conditions of ore deposition in the region.
GENERAL GEOLOGY.
The geology of the Encampment region, when studied in detail, is
found to be very intricate, but the more general features can never-
theless be readily outlined and as readily perceived upon the ground.
Among the most prominent features presented by the region are
certain bands of white quartzite, which the visitor first notes a few
miles southwest of the town of Encampment on the road to Battle.
The bands or reefs of quartzite, which cross the country in a nearly:
east-west direction, are separated from one another sometimes by bands
of conglomerate, slate, and limestone, and in other cases by dikes
of dark diorite. All of these formations have a general dip toward
the south, and frequently stand at steep angles. Taken together, the}'
occupied a narrow wedge-shaped area, extending for a distance of
about 20 miles westward from its point or apex below the mouth
of Purgatory Gulch on the Encampment River, a few miles south oi
Encampment town site. The widest part of the quartzite area id
upon the west, where it becomes covered by surface formations ii
the drainage of Big Sandstone Creek and of Savery River. With thd
158
spencer] ENCAMPMENT COPPER REGION, WYOMING. 159
exception of the diorite, all the rocks mentioned are of sedimentary
origin, having been originally deposited as horizontal beds or strata,
and afterwards thrown into east-west folds by comprehensive forces
acting in a north-south direction.
The diorites are igneous rocks which were intruded into the sedi-
mentary series in a molten state after the greater part of the folding
and compression had taken place. They occur in dikes from a few
feet up to half a mile in width, frequently extending along the strike
for several miles. They are of almost universal occurrence through-
out the quartzite belt, and are also found cutting the granites, gneisses,
and schists which occur both to the north and to the south of the
quartzite area.
The schists of the region are mostly hornblende-schists, which may
be seen in typical development upon the north slopes of the conti-
nental divide in the heads of Jack Creek and North Spring Creek,
and also in the region of Huston Park. The other rocks of the min-
eral belt may be classed under the general names of granite and
granite -gneiss, and all of these appear to have been formed since
the hornblende-schists, though they are probably older than quartz-
ites and associated formations. The formations represented in the
Sierra Madre are of pre-Cambrian age and belong to the most ancient
series known within the Rocky Mountain province. In general, the
formations are well exposed and easily accessible for examination,
though locally they are covered by overwash or by glacial debris.
The topography of the region is more than ordinarily smooth for a
mountainous country reaching elevations above 10,000 feet, a fact
which allows the building of wagon roads to almost any desired locality
at comparatively slight expense.
ECONOMIC GEOLOGY.
The ore deposits of the Encampment region have not, as a rule,
been developed to a sufficient depth to afford opportunity for an
exhaustive study. Hence, while those of the few mines in the dis-
trict which have been opened to a considerable depth have been care-
fully studied, the information obtained with regard to the occurrence
of economic deposits as a whole is largely based upon general geolog-
ical relations ascertained from surface examinations.
Ores. — Copper is the predominant metal of value in the ores of the
district, though there are a few deposits carrying values in silver,
and gold occurs alone in quartz veins, or in variable but always small
amounts accompanying the copper ores. The ores of copper comprise
the sulphides, chalcopyrite, chalcocite, bornite, and covellite and
their usual alteration products, malachite, azurite, chrysocolla, and
the oxides. The silver-bearing ores are argentiferous galena, occur-
ring with sphalerite and pyrite in fissures with a gangne of quartz,
together with calcite, or the carbonate of iron, siderite.
160 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
The copper deposits. — Considered in the most general waj7, the
deposits of copper in the region fall into two classes. The first class
includes all where the mineral is chalcopyrite or copper- bearing pyrite
unaccompanied by oxides, carbonates of copper, or rich sulphides,
except very superficially where the former minerals have been oxi-
dized by surface weathering. Deposits of this sort, which occur
invariably inclosed in undecomposed or "live" rock, are regarded as
original ores. Their distribution is almost universal, and they are
found in all sorts of rocks, frequently without any recognizable vein
material, but sometimes accompanying masses of quartz with a small
amount of feldspar, calcite, or siderite (carbonate of iron). In those
cases where little vein matter is present the ore occurs, as a rule, in
pockets or lenticular masses following the schistose or platy structure
of the country rock, and more or less mixed with the inclosing mate-
rial. No instances were observed where bodies of this character gave
promise of sufficient size or permanence to warrant the expectation
that they will lead to important masses of ore.
As an exception to deposits of the above type where there is no
well-defined lead traceable for any considerable distance upon the
surface, there are others, still without associated quartz, occurring in
strong leads traceable for long distances upon the surface. A typical
example of this variety of deposit is the Verde or Ilinton property.
The Verde lead is a zone along which intense metamorphism has taken
place, involving hornblende-schists, a band of limestone, and some
thin strata of quartzite. The lead seems to follow the limestone,
which in turn appears to lie parallel to the general schistosity of the
region. There is every reason to anticipate that metamorphic zones
of this kind will persist in depth, though the extent to which copper
has been deposited in them must be proved by exploration.
In a third type of original ores the copper pj'rites occur in a
matrix of quartz accompanied by calcite and siderite or by feld
spar. The sulphide here occurs in bunches throughout the mass of
the gangue, and the value of such veins is dependent upon their per-
sistence. Some veins of this nature are lenticular bodies lying with
their longest surface dimensions parallel with the platy structure of
the inclosing rock. Certain of such masses of quartz reach a width
of 50 feet or more, showing in outcrop a length of from twice to sev-
eral times this figure, but these seldom show any considerable amount
of copper, though they are reported to cany a small amount of gold. J
They can hardly prove to be permanent in depth. In other cases the!;
quartz occurs in a disconnected series of thinner lenses, extending
along the same general trend in the schistose rocks. Sometimes these
interrupted veins carry chalcopyrite in promising amounts. Their
probable downward extent and regularity may be closely ascertained'
by a study of their persistence along their strike. If they are irregu
lar and interrupted upon the surface, they are likely to be discon
spencer.] ENCAMPMENT COPPER REGION, WYOMING. 161
tinuous in depth, but where strong and persistent in outcrop they
may be expected to continue in depth. This type includes such
deposits as the Continental in Cow Creek, the Cascade, and the
Kurtz-Chatterton, in each of which it is anticipated that active devel-
opment in progress should settle the question of permanence and
extent of mineralization.
In the ores of the two properties last named there has been some
secondary deposition of ore, but the sulphides are regarded as mainly
primary.
The second class of copper deposits includes all those where the
principal copper minerals are rich sulphides, such as chalcocite or
copper glance, covellite, and bornite, with or without high-grade cop-
per pyrites. In the surface portion of such deposits large amounts of
oxide and carbonate ore are found, and they are commonly capped at
the outcrop with strong gossan. Also the inclosing country rock is
often to a greater or less extent decomposed.
Ores of this character are regarded as due to secondary concentra-
tion or enrichment of ore bodies originally of low grade, through
processes similar to those which have produced bonanza deposits in
many other copper camps.
The secondary deposits of the Encampment district have been thus
far the only ones supporting productive mines. The ores of the
Charter Oak, Doaue-Rambler, and Ferris-Haggarty mines are of this
nature. At the Charter Oak, where the country rock is granite and
diorite, the deposit appears to have been extremely irregular, but in
the other mines mentioned the deposits show considerable regularity
in their occurrence. The ore bodies, inclosed in quartzite of sedi-
mentary origin, occur in zones of shattered rock which follow the bed-
ding of the quartzite. Course's of easy circulation for underground
water have been afforded by local shattering of the rock, which
doubtless determined the position of original deposition, and later
allowed of concentration to the form in which the ores are now found.
In both the Doane-Rambler and the Ferris-Haggarty the secondary
ores have been opened to a depth of more than 300 feet, though in
neither instance lias the lowest level of the workings penetrated
Bore than a short distance below the beds of the gulches adjacent.
The question of the permanence in depth of these rich secondary
lores need not be discussed here, since it is a subject which will soon
be settled in a practical way by the developments now in progress.
Thus far there seems to be no sufficient reason for supposing that the
[bottom of the zone of enrichment has been closely approached in
I either mine.
From the present study of the region it appears that the future of
|bhe district must depend very largely upon the discovery of addi-
tional deposits of the secondary class or type. That such deposits
Bull. 213—0:3 11
162 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
exist it seems fair to anticipate, but the best method for their diseov- 1
ery must be based upon a recognition of their character as distinct
from the primary ores.
Secondary ores will not be found where the inclosing rocks are tight |
and impervious to the circulation of atmospheric waters. They requ ire t
loose formations due to brecciation or crushing of the country rock, as ;
in the cases mentioned, and in some cases it is to be expected that
the country rock will be greatly decomposed. Several locations were ! I
noted by the writer where gossan was present in encouraging amount, ! {
but where no adequate work had been done to prove the condition of,
the inclosing country rock or the significance of the gossan. Other!
properties show the presence of rich sulphides in crushed and decom-fl
posed diorite, and it is believed that these are worthy of careful
investigation.
RECONNAISSANCE EXAMINATION OF THE COPPER DEPOSITS
AT PEARL, COLO.
By Arthur C. Spencer.
DESCRIPTION OF THE REGION.
Pearl, Colo., lias been a post-office for several years, but only within
the last three years has it become known as a mining camp. It is
located in Larimer County, near the northern boundary of Colorado,
about 20 miles southeast of Encampment, Wyo., and an equal dis-
tance south of the New Rambler copper mine.
The area contiguous to Pearl over which active prospecting has been
carried on for the last three years is drained by a tributary of the
North Platte River, now known as Big Creek, but represented on the
maps of the Fortieth Parallel Survey as Grange Creek. The region
is mountainous, lying as it does in the heart of the Sierra Madre, or
northern end of the Park Range, which forms the westernmost of the
three elevated zones which compose the Rocky Mountains in this lati-
tude. The crest of the Sierra Madre, from 10 to 25 miles south and
west of Pearl, forms the continental divide separating the waters of
Big Creek from the head of Elk River, which flows to the Yampa
and thus to the Green River.
Eastward from Pearl there is an easy line of travel to North Park,
and toward the west the old Government road leading from Laramie
to Hahns Peak gives a route to the head of Encampment River.
The town itself is picturesquely situated in a broad basin near the
junction of several wide valleys, which give access to all parts of the
adjacent mountains. The elevation of this basin is about 8,000 feet,
but within a distance of 10 miles there are mountains which rise to an
altitude of from 10,000 to 12,000 feet.
The surrounding slopes are covered by a dense growth of pine and
spruce, while the valley bottoms, which were originally covered by a
luxuriant growth of wild grass, are now devoted to the cultivation of
timothy and other grasses for hay.
GENERAL GEOLOGY.
The geology of the region is similar to that of a portion of the
Encampment district, though the pre-Cambrian quartzite, which is
163
164 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
a noticeable and important feature of that district, is not found. !
The country rock over large areas is a generally coarse though varia-
ble granite of a red or gray color, frequently cut by small dikes of
pegmatite. Minor areas are covered by diorite of a variable charac-
ter. Though usually massive, as observed in limited outcrops, both
the granite and the diorite, when considered in a broad way, show
banded structures, due to a more or less evident parallel arrangement
of the constituent minerals, and to the separation of light and dark
minerals into narrow plates. These variations are most noticeable in
areas where the granite preponderates, and in this rock the variations
range from light-colored siliceous phases to very dark-colored basic
types containing a large amount of mica and hornblende. Certain of \
the dark bands intimately connected with the granite can be distin- j
guished only with difficulty from the diorites which occur in larger
independent masses. The structure of these massive diorites is ty pi- j
cally gneissic, and outcrops which are not banded are rarely observed. I
DEVELOPMENTS.
Nine prospects showing the presence of copper minerals in encour- j
aging quantities were visited. These have been developed by from
50 to 200 feet of workings. Two days were devoted to a rapid exam-
illation of the phenomena presented, and these observations form a
basis for the notes which follow.
In every case where limonite or iron oxide was found at the surface
this material has proved to be only a shallow capping; and the zone
carrying oxides and carbonates of copper beneath it, when present!
at all, has been unimportant. In no instance did any property vis-
ited fail to show unaltered pyrite and chalcopyrite at a moderate
depth from the surface, but there are as yet no thoroughly developed!
deposits, though on every hand intelligent efforts were being made to
prove the value of the various discoveries.
Big Creek shaft. — The property of the Big Creek Mining Company I
lies northwest of Pearl at a distance of about 2-J- miles. The general
character of the country rock in the vicinity is granite-gneiss, but
there are frequent bands of diorite which vary from gray to almost
black, with changing proportions of hornblende and feldspar. The;
granite normally contains mica, but locally this mineral disappears
and certain fine granular streaks in the granite have the appearances
of being quartzite, though in fact they are made up of quartz
and feldspar. The country rock at the shaft is a granite-gnei
which contains more than the usual amount of mica. The workings
were filled with water and therefore not accessible, but from the
direction of the shaft the course of the vein seems to be about
N. 00° W. The vein is said to stand nearly vertical for a distance
of 100 feet from the surface, and then to dip about 70° S. to the
bottom of the shaft, which is 145 feet deep. From the material
fcpBNCER.] COPPER DEPOSITS AT PEARL, COLO. 165
found on the dump the ore is seen to be chalcopyrite occurring
with ferruginous zinc blende in a segregation vein composed mostly
of hornblende, but carrying a small amount of calcite. The country
rock is very platy or schistose, but the vein material seems to be
massive. The relations of the sulphides to the hornblende and cal-
cite show that they are contemporaneous minerals. Unfortunately
the vein does not afford a visible outcrop, so that its relations to the
country rock can not be studied in detail.
Sierra Madre shaft. — This property is located near the State line
and about 1-J miles north of Pearl. A mineralized zone about 7 feet
in width, having a course N. G0° E., occurs in dark micaceous gneiss.
This zone, which is parallel to the structure of the gneiss, may be
divided into two portions, one of which is made up of entirely mas-
sive hornblende, free from banding and carrying pyrite, chalcopyrite,
and zinc blende, with a small amount of galena; the other portion is
a light-colored banded rock resembling the sugary granite mentioned
as occurring near the Big Creek shaft. This portion of the vein car-
ries zinc blende and a small amount of pyrite, in bands parallel with
the course of the mineralized zone. The hornblende vein presents no
sharp walls against the inclosing gneiss or against the siliceous por-
tion of the mineralized zone, and it seems to have been formed by seg-
regation accompanying the general metamorphism wiiich produced
the banding of the country rocks.
The zinc blende occurring in the siliceous gneiss possibly replaces
the dark-colored minerals which it originally contained, and was
probabty introduced at the time the hornblende vein was formed.
Lizzie and Tally claims. — These are contiguous properties tying less
than half a mile north of Pearl. In this region there are rapid
alternations of granite and diorite in many varieties. The mineral-
ized zones seem to conform to the structure of the gneiss, which has a
course about N. 50° E. The two shafts appear to be located upon
different zones, and still other zones are present upon the claims. In
both shafts bornite and chalcocite have been found, but these minerals
are confined to the upper portions of the workings.
Swede or Hawkey e group. — These claims lie about 2 miles south-
east of the town. In general the occurrence of the ores seems to be
similar to that in the Big Creek and Sierra Madre claims. Granite is
the usual country rock, but bands of diorite are also present, and the
immediate walls of the ore-bearing material are of an intermediate
type of rock. At the Copper Crown shaft, which is the principal
opening, the course of the vein is N. 10° W. The vein matter is con-
siderably weathered, but consists of pyrite, chalcopyrite, and zinc
blende, occurring in a gangue of calcite and serpentine. Occasional
specimens show that the serpentine has been derived from the altera-
tion of hornblende or pyroxene, which indicates that the deposit is of
the same nature as the Sierra Madre.
166 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bum.. 213.1
Wolverine claims. — This property, owned by the Cold Water Min-
ing Company, is located about 2^ miles south of Pearl. The eountrJ
rock is extremely variable, showing all gradations from black dioritet
to pink granite, and the granites are in part hornblende-granites
related to the diorites. The ore in the discovery shaft is chalcocitel
containing disseminated specks of chalcopyrite and zinc blende. I
This ore is of a very friable nature, and on exposure crumbles to a1
sand. An examination of the material thrown out and of the neigh-'
boring outcrops shows that the ore has resulted from the replacement!
of biotite in a rock originally composed of quartz, biotite, and garnets
Of these three minerals the quartz alone remains in the form of a
granular gangne surrounded by the sulphides of copper. The extent
of this ore and the shape of the ore body have not been ascertained,,
but surface outcrops are sufficient to show that the mass of the rock in
which it occurs is rather limited, having the shape of a wedge which!
disappears toward the southeast.
The shaft where the work is now being done is situated a few feet<
north of the point of the wedge of granite, and through its top there'
passes a vein having a course N. 40° W. This shaft is in pink gran-'
ite, but diorite is present on both sides. The general trend of thei
banded structure is N. 80° E. The various rocks near the mouth of)
the shaft are cut in an intricate manner by small dikes of pegmatite,
and certain coarse phases of granite in the vicinity contain red oxide1
of iron, which has been derived probably from magnetite. Some good;
specimens of chalcopyrite have been taken from the shaft, but no
regular deposit of the mineral has been proved thus far.
Mount Zirlcd shaft. — The shaft on the property of the Mount ZirJ
kel Company is located about 2,500 feet northeast of the Wolverine]
shaft, and while the general nature of the country rock is identical,!
the ore here occurs in a different manner, nainelj7, in granite pegma-
tite and in a broken or brecciated gneiss adjacent.
The shaft has been sunk to a depth of 185 feet, and drifts started
at 71 and 155 feet. The pegmatite is extremely coarse grained, and
is composed of quartz and cream-colored feldspar, with occasional
flakes of mica. This material has been fractured and chalcopyrite
has been deposited in the openings thus formed, sometimes as a filling
of brecciated bands, and at other times occurring along cracks which
pass from the feldspar into the quartz. As shown in the workings,!
the pegmatite has a course approximately N. 80° E. For the first 35
feet there is a dip of 70° S., then for 90 feet the vein stands nearly
vertical, and below 125 feet it dips perhaps 75° N. The pegmatite is
inclosed in a much broken gneiss of variable composition. On the)
north side of the vein diorite and granite seem to be intricately mixed,
and here local pockets of chalcopyrite are found in the 155-foot level,
and also in the discovery shaft at the surface, where there is a well-
defined streak of iron oxide stained with green copper mineral, evi-\
spencer.] COPPER DEPOSITS AT PEARL, COLO. 167
Sentry due to surface weathering of sulphide ores. The ores in the
pegmatite are not accompanied by any contemporaneous quartz, but
this mineral is present in small amount in the ores which occur in the
country rock. The occurrence of ore, both in the pegmatite and in
the inclosing rock, is very irregular, and seems to depend upon the
fracturing which the rocks have undergone. There are two systems
of joints, which, taken together with the gneissic structure, and with
frequent rifts of low inclination, result in the production of angular
blocks, by which the size and form of ore masses are often limited.
The ore occurs, in some instances, as a probable replacement of coun-
try rock, and in other cases as a deposit between adjacent blocks.
The relations observed tend to show that the ores have been intro-
duced in a manner independent of the formation of the pegmatite and
subsequent to it.
Gold King claims. — The workings of this property are located
between 3,000 and 4,000 feet east of the Mount Zirkel shaft. The
shallow openings which were visited seemed to have been located on
carbonate stains occuring along a sheared zone in red granite. The
heaviest stains amount almost to impregnation, and these occur at
the intersection of closely spaced joints. In the granite near by there
are certain bands which are very coarsely crystallized, and which
carry red oxide of iron, probably derived from magnetite. Besides
the large amount of granite there are also outcrops of diorite near the
workings.
Bound Top, Copper Queen, and Big Horn. — These claims are
located in close proximity to one another, and distant about 3 miles
from Pearl in a southerly direction. The surface openings which
constitute the development of the Round Top property show the pres-
ence of yellow sulphides and of zinc blende in a siliceous vein-like
segregation following the banding of the gneiss, which forms the
country rock. It seems probable that the sulphides have been intro-
duced in the form of replacements of hornblende grains in the streaks
in which they occur.
On the Copper Queen claim, about 400 feet southeast of the last, the
developments consist of a shaft about 30 feet in depth. The materials
thrown out show the presence of a mass of hornblende rock in the
form of a vein-like segregation in diorite-gneiss, which forms the
country rock. Upon the immediate walls of the vein the diorite
looks like hornblende-schist, but the microscope shows that its platy
structure is due to recrystallization and not to crushing. It is there-
fore concluded that the vein matter and wall rock are of the same age
and origin. The vein matter is entirely granular and massive, in
which respect it corresponds with other occurrences that have been
mentioned. Along with the hornblende there is some quartz, and
this mineral is largely confined to coarse portions of the vein, where
calcite is also found. The metallic minerals are chalcopyrite, iron-
168 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
bearing zinc blende or black jack, and pyrrhotite. The latter mineral
was tested for nickel and cobalt, neither of which was found to be
present.
The Big Horn shaft is located about 600 feet from the Copper Queen
opening, in a direction S. 20° E. The country rocks are a schistose
diorite, which breaks up into pencils or rod-like pieces instead of
platy fragments and ordinary schist. The pencil structure is pro-
duced by cleavage in two directions — N. 80° E. and N. 10° W. — the
former being somewhat the more prominent.' A nearly horizontal
rifting is noticeable both in the surface outcrops and in the mine
workings. At the Go-foot level a drift 25 feet in length, running
toward the southeast, shows a vein of hornblende gangue, carrying
chalcopyrite in varying amounts.
The width of the vein varies from 18 to 36 inches, but it is not con-
tinuous toward the northwest, and it appears to be a lenticular segre-
gation conformable to the structure of the country rock, which strikes
N. 80° W. at the end of the drift, with a nearly vertical dip. The
vein matter sometimes incloses fragments of the country rock, and
while the ore occurs largely intercrystallized with the hornblende, it
also impregnates the country rock to a distance of 2 or 3 feet. At
the bottom of the shaft a mass of quartz occurs, about 30 inches
across, which appears to cross the trend of the country rock. The
formation of this quartz is probably distinct from that of the horn-
blende, since the latter contains little or no quartz.
Grand Republic. — This property is located about 3 miles southeast
of the Big Horn. Here the country rock is made up of alternating
zones of granite and diorite, each of varying composition. The loca-
tion seems to have been made on a 3-foot vein of vitreous quartz
carrying some fresh chalcopyrite. This vein follows the direction of
the bands in the gneiss, or about N. 30° E, and dips 20° SW. A short
distance east of the vein there is a metamorphosed zone in the diorite,
in which a great deal of massive epidote has been developed. Though
in a very different rock, this zone recalls the metamorphosed volcanic
rocks occurring at the Verde mine in the Encampment region.
The variations in the country rock at this place are extreme. Cer-
tain light-colored bands are so siliceous that upon first sight they have
the appearance of quartzites, while other bands of diorite are nearly
black and contain only a very small amount of light-colored minerals.
Between these two extremes all intermediate types occur.
The development shaft, which has been sunk to a depth of 80 feet,
penetrates a band of black hornblende rock, but though the quartz
vein which has been mentioned dips toward the shaft, it has not yet
been encountered. A small amount of chalcopyrite was found in the
shaft in a massive segregation of hornblende, and a specimen taken at
the bottom shows a small lens of glassy quartz surrounded by dark-
green hornblende, with chalcopyrite disseminated throughout the
spencer] COPPER DEPOSITS AT PEARL, COLO. 169
latter, together with a small amount of zinc blende, revealed by the
microscope.
Other prospects. — At the time the region was visited many other
prospects, apparently similar in character to those mentioned, had
been located, and upon some of them about the same amount of
development had been done. The ores of copper encountered were in
most cases chalcopyrite, as in the properties described, though in one
case large masses of richer sulphides, said to have come from an open
cut about 12 feet in depth, were seen.
PROBABLE VALUE OF REGION.
The rapid examination of a few properties in the vicinty of Pearl
made by the writer can not with fairness be made the basis of any
opinion, favorable or otherwise, concerning the probable future of the
milling industry of the region. All the properties visited are in the
development stage, but the work in progress should soon determine
in a practical way the important questions whether any of the ore
bodies are of sufficient size and permanence to afford commercially
important deposits.
ORE DEPOSITS AT BUTTE, MONT.
By Walter Harvey Weed.
INTRODUCTION.
The geology of the Butte district and its ore deposits formed the
subject of a report published by the Geological Survey as a geologic
folio in 1897. a Subsequent development in the copper mines of the
district, partly as a result of the greatly increased output of the prop-
erties, but mainly because of the very large amount of work done to
prove structural conditions, ore connections, and other evidence for
use in the many lawsuits begun since 1896, has afforded opportunity
to greatly extend the earlier work and to modify conclusions based
upon the earlier incomplete data. A reexamination of the district,
with a special study of the copper deposits, was therefore begun in 1 901.
Owing to the necessity of completing other work for publication, and
to the intricate nature of the study, involving a close1 and detailed
examination of over a hundred miles of underground workings, the
field work was not completed until the autumn of 1902. The later
workings show that the structural conditions are far more complex
than was formerly supposed. The original veins are displaced by
great faults, and these later fractures are themselves mineralized and
again displaced. The working out of this structure has been diffi-
cult because the deposits occur in a body of very homogeneous gran-
ite, the rock alone affording no clue to the amount or direction of
displacement. Nevertheless, the correlation of displaced areas is
fairly satisfactory, based as it is upon a study of the quartz-porphyry
and aplite intrusions in the granite and of the structural and miner-
alogic variations of individual veins.
SITUATION OF THE DISTRICT.
The Butte district is situated in southwestern Montana, in the cen-|
trai part of the Rocky Mountain region. The city which is built
about and over the mines is the largest settlement of the State, while
the neighboring city of Anaconda, 20 miles distant, is a dependent,
a Geologic Atlas U. S., folio lis, Butte Special, Mont., 1897.
170
weed] ORE DEPOSITS AT BUTTE, MONT. 17 1
having been built for and supported by the reduction of the Butte
ores. Smelting' the Butte ores is also the largest industry of the city
of Great Falls. Three transcontinental railways run to Butte, and
its traffic surpasses that of all the other cities of the State combined.
Originally named Summit Valley district, a name which is still
retained in official records, and which is significant of its situation
almost upon the transcontinental divide, where the waters of the
Pacific and Atlantic separate, it is now universally known as rftitte,
a name derived from a sharply conical hill that rises abruptly above
the barren hillside on the edge of the city and forms a prominent
landmark. The area comprising the district is a now barren hillside
on the northern side of a flat valley bottom. This level valley is
inclosed by an abrupt mountain range forming the continental divide
on the east and the snow-capped peaks of the Highland Mountains on
the south. To the westward a low plateau, now cut through by Silver
Bow Creek, separates this valley from the great lake-bed area of the
Deer Lodge Valley.
DEVELOPMENT OF THE REGION.
The Butte district of Montana is to-day the most important copper-
producing area in the world, the product aggregating 2,841,791,572
pounds to the close of 1901, with a total value of $381,209,050. The
discovery of the copper veins of Butte was not made until after the
district had acquired some prominence for its gold placers, and sub-
sequently as a silver camp. The placer gold was first worked in 1803,
the date of greatest activit}^ being in 1867, since which period the
product ion of placer gold has become quite insignificant.
In 1804 the first lode location was made, upon a vein now known
as the Travona. This was the beginning of a period of very prosper-
ous silver mining, and the district became the center of energetic
operations, large mills being erected, with a considerable output of
i silver as a result. This period of active silver mining continued until
1892, when in common with other silver camps of the country the
Butte district suffered a crushing blow. The climax of the produc-
tion of silver ore was reached in 1887, when the different mills treated
about 400 tons of ore per day and the smelters an aggregate of about
100 tons per day, the average yield being about $25 per ton in gold
iind silver.
In the j^ear 1881 the Dexter mill was leased by Marcus Daly, for
the newly organized Anaconda Silver Mining Company, and 8,000
tons of oxidized silver ore, from the Anaconda ledge, Avas treated in
this mill, yielding about 30 ounces of silver to the ton. The ore con-
tained just enough copper to make it unnecessary to add bluestone
Iin the raw amalgamation, but the resulting bullion was very base,
sometimes running only 400 fine. In working the vein a drift running
172 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull.21i1
few inches wide. Mr. George Hearst, visiting the district about 1S82,
selected the site of the present Anaconda shaft as the most suitable
place for future development. At a depth of 300 feet a crosscut run
from the shaft encountered 5 feet of copper glance, and the ore was
extracted and shipped to Swansea. During these early years the cop-
per ores showing on the surface of several of the claims were receiving
attention, and in 1867 an effort was made to smelt some of the ore from
the Uarrot lode.
To Senator W. A. Clark is due the first successful development of
the copper veins of the district. In 1872 and the succeeding two years
he began development work on the original Colusa, Mining Chief, an
Gambetta claims. The ore extracted was shipped 400 miles in wagon
to Corrine, Utah, thence by rail to the East, some of it going to
Swansea, Wales.
One of the purchasers was the Boston and Colorado Smelting Com-
pany, located at Black Hawk, Colo., and in 1879, at Mr. Clark's sug-
gestion, this company formed the Colorado and Montana Smelting
Company and erected reduction works on the present site of the
Colorado Smelter, thus furnishing a local market for the copper as
well as the silver ore of the district. This smelter gave a great
impetus to copper mining in the district, as previously shipments con-
taining 35 per cent of copper from the Green Mountain claim gave no
profit to the shipper after the cost was paid, although the gross value
of the ore was $130 per ton in copper, the average price of that ore
being 18f cents per pound. In silver the ore carried not less than $50
per ton, but the works charged a high price for treatment, owing to '
the presence of arsenic, which made the metal brittle.
Soon after the erection of the Colorado Smelter the Parrot, Montana
Copper, Clark's Colusa, and the Bell Company began smelting opera-
tions. The matte produced by these works was shipped to Eastern
markets for refining. In 1884 the Anaconda Smelter began operal
tions, followed rapidtyby the formation of the Butte Reduction Works,
Boston and Montana, Butte and Boston, and Montana Ore Purchasing
companies. The completion of the Utah Northern Railway from
Ogden to Butte in December, 1881, and the connection of this railroad
with the Northern Pacific at Garrison in 1893, and the coming of the
Montana Central, part of the Great Northern system, in 1888, and of
the local branch of the Northern Pacific in 1889 — all added to the
prosperity of the camp.
In the history of Butte the metallurgical advance in the treatment
of the ores has been very steady; the free-milling silver plants gave
place to chlorination and roasting, and these in turn to other improve-
ments, so that the ores which could be profitabl}7 treated became lower
and lower in grade. With the great decline in silver of 1892-93 the
silver-mining industry of the district became less and less important,
until in 1890 all the large plants were closed down, and since that time
wekd.] ORE DEPOSITS AT BUTTE, MONT. 173
the mining of silver ores has been of relatively slight importance and
has been carried on chiefly by leasers working in the old properties.
The importance of Bntte as a producer of silver and gold at the pres-
ent time is due to the fact that the copper produced contains 0.0375
ounce of silver and $0.0025 in gold for each pound of copper produced,
or approximately 2£ cents in the precious metals for each pound
of copper. On this basis the Butte copper mines yielded in 1801
8,550,000 ounces of silver, which, at 55 cents per ounce, amounted to
$4,702,500, together with $570,000 in gold, or a total of $5,272,500 in
precious metals. Thus we see that in the production of precious
metals the Butte district ranks among the great producers of the
world. The total of 2,841,791 ,572 pounds of copper has been produced
from a tonnage which may be safely estimated as at least 100 pounds
per ton of ore, and on this basis over 28,000,000 tons of copper ore
have been mined in the Butte district down to the close of 1901.
ROCKS OF THE DISTRICT.
The* rocks of the ore-bearing area are all igneous, the district form-
ing part of an extensive region of Tertiary igneous activity. The
prevailing rock, and the one in which all the veins occur, is a dark
basic-gi'anite, technically known as quartz-monzonite, which is a part
of a great mass of granitic rock extending from the snow-capped
Highland Peaks*, seen 20 miles south of Butte, northward to Helena.
This great mass of intrusive igneous granite is surrounded by altered
limestone and other sedimentary rocks, and is in part covered by
dark-colored andesite (both massive and fragmeutal varieties) of ear-
lier age. Neither sedimentaries nor andesite occur in the district.
Throughout the Butte mining district the granite is remarkably uni-
form in color, texture, and composition, and the name Butte granite
has been applied to it. This rock -is cut by dikes and irregular intru-
sions of the Bluebird granite, a white aplite a composed of quartz and
feldspar, with a little mica. This rock, though intrusive in the gran-
ite, is supposed to have separated from the same magmas as the Butte
granite and to have penetrated fissures in the latter while it was still
hot, as the aplite is found in all sorts of small veins and masses which
do not show any chilling along the contact. The rock is found fre-
quently, but in relatively small masses. In the copper-bearing area
the_Modoc porphyry appears in lenticular dikes, traversing both vari-
eties of granite in very irregular fissures. It is a light-colored rock,
carrying large and distinct crystals of feldspar and quartz in a dense
ground mass, and is technically designated rhyolite-porphyry or quartz-
porphyry. After the intrusion of the Modoc porphyry extensive frac-
turing occurred, with vein formation, the veins cutting the porphyry
in many instances. After the formation of these earlier veins, renewed
"Called "granulite1' by . some writers— a name applied by German geologists to a variety of
schist, but by French petrographers to aplite.
174 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
and very violent volcanic activity began, resulting in the intrusion
and eruption of rhyolite, forming dikes cutting across the veins, and
also great sheets and masses of fragmental material.
The Big Butte is formed of rhyolite, both fragmental and massive,
and this rock occurs in dikes cutting both the granite and veins in the
silver area, while the fragmental form covers a large extent of coun-
try west of the mines. These rocks are the product of volcanic action,
and the Butte is the eroded remnant of a small volcano.
The granites are of Tertiary age, for at the borders of the batholith
late Cretaceous strata are cut by the intrusion, and, moreover, included
fragments of the early Tertiary andesites occur in the granite. The
rock is cut by rhyolite dikes, and as rhyolite ash-showers form lake
beds containing Miocene vertebrate remains, the granite and the
veins are of earlier age, probably Eocene or early Tertiary. West of
the district the lake beds appear, formed in a great Tertiary lake that
filled a long and relatively narrow valley extending from south of Dillon
in southern Montana to (4arrison, a valley which was warped by later
earth movements that drained it and carried the continental divide
across its floor.
STRUCTURAL FEATURES.
The Butte Mat, a level valley bottom south of the city, contains no
lake beds; it was formerly a normal erosion valley formed by the con-
vergence of streams from east, west, and south of Butte, and was
subsequently depressed by faulting along the base of the mountains
east of Butte, which reversed its principal tributary and resulted in
the filling of the valley by torrential debris and wash from the
adjacent slopes. This faulting altered the ground-water level of the
ore-bearing area and played an important part in concentrating the
ores. The district is thus shown to be one of deep-seated igneous
rocks, subjected to fracturing at various periods, the resulting frac-
tures being in part filled by dikes, in part by veins, and in part
displacing the veins; it is a region of continued and continuing
crustal adjustment.
The veins occur in an area showing few outcrops, the rocks being
altered by decomposition and disintegration and forming smooth
slopes; only rarely do the granite bowlders characteristic of the
western part of the district show in the copper area. A few of the
copper veins outcrop, but most of them, even the largest., are recog-
nizable at the surface only by inconspicuous debris or do not show
at all, a fact which has led to many lawsuits to determine ownership
of ore bodies.
The district embraces a well-defined area of copper lodes surrounded
by silver veins with transition ores at the borders. Though the veins
of these two areas present a strong contrast in mineralization and
charaeter, the vein systems appear to be similar, so that the area may
be described as a whole.
weed.] ORE DEPOSITS AT BUTTE, MONT. lib
The rocks of the entire district are traversed by a multiplicity of
joints and fractures. These belong to three well-defined systems, as
may be seen in excavations in the city or, more clearly still, in the
great bowlder outcrops to the northeast where the veins are seen to
be merely mineralized fissures, the exceptional instances in which
the fractures have been channels for mineralizing solution. In the
copper area the rocks are intersected by a multitude of fissures*
which near the surface are filled by quartz and iron oxide, with
rotted or disintegrated granite between, soft enough to yield to the
pick. In depth the lesser fractures are not filled and are therefore
less conspicuous.
The veins of the district, both copper and silver veins, belong to
three distinct systems. The oldest lodes have a general east- west
course, the Parrot, Anaconda, and Syndicate lodes being examples.
Another set of fractures has a northwest-southeast course, and lias
displaced the earlier veins. A still later set has a northeast course
and has displaced both the earlier systems of veins. The first two
systems are heavily mineralized; the last shows a little endogenous
ore, but the material mined is mainly the ore broken off from earlier
deposits and included in the fault debris. This discrimination of the
I different vein systems and the recognition of the faulting of one set
by the other and of the resulting mineralization is the result of the
study of the district made since the Butte folio was published. It
has been made possible by the enormous development work expressly
made to develop the structure and continuity of veins for the various
lawsuits between the mining companies.
The silver veins surround the copper lodes on the north, west, and
southwest. Their course and geologic relations are very similar to
those of the copper veins, but their structure and mineralogic charac-
ter are different. The silver veins contain sulphide of silver, blende,
pyrite, and a little galena, and commonly contain no copper save near
the border of the copper area, where, though occasional bunches of
copper ore occur, it consists of chalcopyrite and more rarely still tetra-
hedrite, minerals which occur rarely and very sparingly in the copper
lodes. The gangue consists of quartz with rhodonite and rhodochro-
site, and shows marked banding and crustilication, in strong contrast
to the structure of the coj)per veins. These silver veins form very
prominent outcrops, the quartz being stained black by manganese
oxide. The veins are largely due to the filling of open fissures, and
show but slight alteration of wall rock. They are displaced by and
traversed by faults with friction breccias and alteration clays like
those in the coi>per area.
THE COPPER VEINS AND MINERALS.
Several of the copper veins were, as is well known, at first worked
as silver veins. The upper portion of the veins consisted of quartz
176 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
somewhat stained by iron, but not like the great iron gossan raps of
other regions. This extends to a variable distance below the surface,
200 to 400 feet in some instances, where it is replaced by partly oxi-
dized and decomposed copper ores that form the upper limit of the
remarkable glance, enargite, and bornite ore bodies of the district.
Carbonates and Oxides are rare.
The copper minerals occur in quartz-pyrite veins of remarkable
width and extent. The Anaconda ledge is frequently Id) feet wide
and will average half that width, as will also the Syndicate lode.
The copper minerals of the Butte ores consist chiefly of chalcocite
(copper glance), bornite (peacock copper), enargite (sulpharsenide of
copper), and cupriferous pyrite. Govellite (cupric sulphide) occurred
in considerable amount in one or two mines, but forms an insignifi-
cant percentage of the total output. Tetrahedrite (gray copper) and
chalcopyrite (copper pyrite) arc even rarer than the last-named min-
eral. Until 1900 copper glance constituted the most important ore
mineral of the veins, but it is now nearly equaled in quantity by
enargite. In the great ore bodies of the upper levels of the Anaconda
veins glance occurred in masses of nearly pure lead-like mineral 2|
feet or more wide. In depth the mineral shows a more crystalline
structure, and ii is found in all tin1 mines in greater or less abundance
and purity, but in the great bulk of the ores it forms small grains
scattered through the ores.
Bornite is less common than glance, and is practically restricted in
occurrence to the veins in the western part of the copper area, where,
however, ii occurs in great abundance, forming t lie chief ore of the
( Original and Parrot mines.
The gangue of all the veins is largely quartz, though there is also a
large amount of altered granite with veinlets and bunches of ore. The
vein walls are often defined by (day selvage, but these prove almost
invariably to be due to post-mineral fracturing. More frequently
there is a fading of ore into country rock, a feature characteristic of
replacement deposits.
THE ORES AND THEIR DEPOSITION.
Cliaracter of tin ores. — The copper ores average 55 per cent silica
and 16 per cent iron. About 15 per cent of the tonnage mined is
first-class ore, averaging 12 percent copper; the remaining 85 per cent
carries 4.8 per cent copper, and is treated in concentrating mills, the
resulting product containing but 15 to 20 per cent of silica, while the
copper is increased to 18 per cent.
The ores contain gold to the extent of about -2\ cents to each pound
of copper, with 0.0375 ounce of silver. Native gold has been found
upon crystallized glance, but with this exception no gold or silver
minerals are recognizable in the copper ores. It is estimated that the
total production of copper ore has been about 31,000,000 tons, averag-
weed.] ORE DEPOSITS AT BUTTE, MONT. 177
ing 5 per cent copper. The amount of arsenic (and antimony) pres-
ent is very large, it being estimated that over 32,000 pounds a year
pass off in smelter fumes. Tellurium is present in very small
quantity in the ores, amounting to 2^ ounces, or 0.008 per cent, in
the crude copper upon the converters. It is recovered in electrolytic
refining.
Ore deposit/ion. — Three distinct periods of ore deposition are recog-
nizable in the deposits of Butte. As many of the ore bodies are of
composite character and derive their contents in part from each one
of these periods, a careful study is necessary to discriminate the
1 evidence and results of each period. In general it is necessary to
differentiate primary deposits, or those formed of material brought
to and deposited in the veins from outside sources, and the so-called
"secondary" deposits of transposed and redeposited material. The
former constitute the normal vein filling, the latter both the bodies
of rich ore that have made the district famous and masses of low-
i grade, concentrating ores. As a general statement, it may be said
that the deposits of copper glance are secondary.
The original source of the metallic contents of the primary deposits
is still an unsolved question. It has been inferred by Mr. Emmons
that, in the lack of direct evidence, "It is probable that circulat-
I ing waters have somewhere in the depths extracted the metals from
parts of the granite mass." To the writer the mineralogic evidence
1 and the intimate connection between periods of ore deposition and
igneous activity indicate a possible derivation from magmatic ema-
nations— so-called mineralizing agents in waters partly of magmatic
origin, mingled perhaps with predominating meteoric waters
In general it may be stated that the original mineral-bearing solu-
tions were probably hot and ascended through fractures in the granite.
I The copper deposits are almost entirely replacement deposits formed
I by waters ascending through mere cracks and attacking and replac-
ing, particle by particle, the adjacent rock. The silver veins, on the
contrary, are in large part due to the filling of open fissures, though
replacement deposits also occur. In the replacement deposits there
is a general lack of definition between country rock and ore, a wide
zone of altered decomposed granite alongside of the vein, and com-
monly an impregnation of the rock between the individual veins of a
lode with ore minerals. This is especially noticeable in the eastern
part of the copper area, in Leonard, Rarus, and adjacent mines. In
the former an ore body is stoped out for 135 feet in width, consisting
of altered granite, sheeted and intersected by a multitude of small
veins crushed by later movements and impregnated by primary
minerals in part replaced by secondary glance.
In the central part of the copper area fresh unaltered granite is
uncommon. There has been local development of intense thermal
activity. The rocks are closely fissured as a result of several periods
Bull. 213—03 12
178 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
of fracturing, and the mineralizing solutions have penetrated and
altered the rock between the fissures, converting and changing the
rock to what is conveniently called pyritized granite, since the horn
blende and mica are altered to pyrite.
The deep development work of many of the mines shows a decided
change in the amount of mineralization of the fractures. There is
an increasing number of small veins of quartz and pyrite separated
by altered granite. Some of the large lodes whose entire width is
workable pass downward into a cluster of small veins of quartz and
pyrite separated by altered granite. In other words, the replacement
of inter- vein material by ore decreases with depth. There is also a
decided increase in the number of small fissures devoid of ore and
filled by friction breccia, but showing trifling displacement. This is
particularly noticeable in the levels 1,600 feet or more below the sur
face. On the other hand, some of the newer fault veins that show
little or no ore in the upper levels contain pay ore below, because the
open nature of the fault material permitted a deeper seepage than
usual of descending waters.
Secondary enrichment. — The enormous bodies of copper glance
which have made the Butte district famous are probably the largest
and best examples of secondary enrichment known. The fracturing
of the veins has permitted the access of meteoric waters, which, dis
solving the copper from the lean ores of the oxidized zone, deposit it
by reaction with pyrite, in the depths. These deposits were greatest
in the upper level of the mines and have gradually lessened with
depth. In some of the veins the lower limit of enrichment has been
reached, in others the deepest workings still show these enrichments.
In general there is a marked association of faulting of the veins
with bodies of rich ore, and these faulted areas are wet, so that the
miners say: "A dry and tight vein is barren: a wet and crushed one
is rich." This is particularly marked where the veins contain much
pyrite, though the glance is more conspicuous in white quartz. In
the deeper levels newly deposited quartz occurs with the glance. In
the deepest levels, 2,000 feet or more below the surface, rounded
masses of glance 2 and 3 feet across occur in crushed quartz contain-
ing relatively little pyrite.
Change of character of mineralization i villi, depth. — The most nota-
ble change in mineralization with increasing depth is the greater
abundance of enargite. In the eastern part of the copper area, in the
Rarus Hill and its vicinity, this ore extends upward to the oxidized
zone, sometimes very nearly to the surface. West of here there is a
notable increase of enargite in depth, the mineral occurring for the
first time in the very deep level of some mines (i. e., 1,800 to 2,200
feet), an association that also prevails in some of the later veins, such
as the Blue, as well as in the older ones.
Influence of country rook.— There is a distinct association of the
weed.] OEE DEPOSITS AT BUTTE, MONT. 179
copper deposits with the Modoc porphyry occurrence, since the most
productive lodes occur in the area penetrated by this rock. The
veins cross the porphyry, however, even the earliest ones, and hence
the vein fractures are of later occurrence.
There is also a distinct genetic relation between ore and country
rock, as a result of the deposition of the ore by metasoinatic replace-
ment. Thus the Anaconda ledge is low grade where it crosses either
the Bluebird granite or the Modoc porphyry, a feature explainable by
the lack of easily replaceable, dark-colored, ferromagnesian minerals
in those rocks.
THE VEIN SYSTEMS.
As a result of extensive legal development work the evidence is now
conclusive that the east-west veins have been faulted. The identity
of the Original-Parrot and Anaconda lodes is conclusively established,
the displacement being due to the Blue vein. Farther east the Ana-
conda ledge is again thrown to the north by the Mountain View fault,
the displaced segment forming the South ledge of the Mountain View
mine, terminated eastward by the Rarus fault, throwing the lode
southward, so that its eastward extension appears in the Rarus mine.
The same faulting has displaced the other veins of this part of the
district.
Earlier veins, east-west system. — The great veins of the district, the
Anaconda, Parrot, Mountain View, West Colusa, Syndicate — in fact,
all the great producers — belong to this east-west system, in which
the trend is remarkably uniform, considering the length of the veins.
The Silver Bow vein is a marked exception. There is some evidence
to show that certain southeast fractures were mineralized in the ear-
liest vein-forming period, and some of them reopened when the later
faulting occurred.
These earlier east-west veins are distinguished as lodes or com-
i pound veins. They differ in structural and mineral character from the
later lodes, and, except where faulted and enriched, lack the high sil-
ver contents of the veins formed later. Fortunately they have been
extensively fractured by strike faults, as well as the two other vein
systems noted.
Northwest fault veins. — The northwest system of fractures faulted
and displaced the east- west veins. The three largest veins of this
system, the Blue vein, Mountain View vein, and Grey Rock vein, are
mineralized, but not so generally as the older veins; the ore occurs in
chutes and is quite high grade and shows enrichment. The Blue vein
has been developed for over a mile, and to a depth of 1,000 feet, prov-
ing a heavy producer in several mines. It is cut and displaced by a
northeast fracture in the Parrot workings.
Northeast fault veins. — The veins of both the east- west and the
northwest systems are cut and displaced by those of the northeast
180 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
system. The largest and best-known example of this is the Rarns
fault, and the ownership of immensely valuable ore bodies has hinged
upon the geological conditions in the Rams and adjoining claims. A
careful and prolonged examination of all the accessible workings of
these mines, including stopes, has resulted in the establishment of
the following facts:
The Rams faults have cut and displaced all the veins. The cut-off
is as sharp as if made by a knife, and high-grade ore abuts against
fault breccia. The veins displaced are so close together that on cer-
tain levels the cut-off ends of different veins are opposite. The fault
is compound, consisting of two fissures, the easterly with a dip of
45°, the westerly with a dip of 30°, and these fissures differ somewhat
in strike. The interfault block is crushed and the included vein seg-
ments are broken and their orientation is disturbed by a tilting of the
block. The actual fault fissures are marked by attrition clay con-
taining rock and mineral fragments. When indurated by infiltrating
solutions this resembles the quartz-porphyry. As the interfault
material contains workable ore bodies, stoping is sometimes continu-
ous from one vein across the fault to another. Whatever the legal
construction may be, there is no geological continuity. There has
been some ore deposited in the fault fissure, but not sufficient to form
a new north-south vein along the fault, being confined to the prox-
imity of older ore, upon and about which it was precipitated.
The Rams fissure has now been developed to a depth of 1,600 feet
and its existence established for a distance of 1\ miles. Other fissures
belonging to the Rams system exist in many parts of the district,
notably at the Original, Diamond, and Leonard mines, in which
extensive mineralization has taken place.
COPPER DEPOSITS OF THE APPALACHIAN STATES.
By Walter Harvey Weed.
INTRODUCTION.
Copper deposits occur at intervals along the Appalachian Mountains
and the Piedmont Plateau to the east, extending from Canada to
Alabama. The earliest known copper mines of the continent are
included in this region, and many interesting historical facts are
associated with them. The geology of so extensive a region is neces-
sarily varied. The rocks are in most cases metamorphosed and of
the types known as chloritic schists and hornblende-schists ; but their
true nature is disclosed when the methods of modern petrographic
research are applied to them, and in most cases the original nature
and origin of the rock can be made out. It would be surprising that
these deposits have not been studied in the light of our newer knowl-
edge, both of petrology and of ore deposits, were it not for the fact
that for many years past they have been of but little or no economic
importance, and their workings have been filled by water and inac-
cessible.
While engaged in the collection of data to support or disprove the
theory of secondary deposition and enrichment, a number of these
old and formerly well-known mines were examined, as well as several
newer properties whose development was inspired by the remarkably
high price of copper in 1900-1901. The result of these examinations,
necessarily brief and made primarily for the object stated, has been
in part already published, but, the subject appearing attractive and
the investigation timely, it was decided to extend the work and, from
time to time, as opportunity offers, to examine and study all the
known copper deposits of the Eastern, Middle, and Southern States.
Early in this work it was recognized that, while many deposits arc
of similar character, others present marked differences in mineral
contents, structural character, and association. This led to an attempt
to group deposits of similar nature, so that a description of a type
would answer for many. This was done in a paper entitled "Type
Copper Deposits of the South. " a Since then several copper properties
in Maryland and New Jersey have been examined and found to be
still different in character from those described.
-(Trans. Am. Tnst. Min. Eng., 1899.
181
182 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
NEW JERSEY DEPOSITS.
The New Jersey copper ores occur in the eastern part of the State.
They were worked more or less continuously from colonial days until
some thirty years ago. Several properties have recently been reopened,
and in one instance extensive development work has been carried on.
The ores all occur at or near the contact between the shales and sand-
stones of the Newark group (the red sandstone series of Triassic age),
and the trap rocks. These traps all occur tilted at gentle angles,
commonly conformable with the shale beds. Orange Mountain, and
the second and third mountains back of it, collectively known as the
Watchung Mountains, are formed by these trap sheets, the sand-
stones forming the intervening valleys and foot slopes. These traps
are lava flows contemporaneous in age with the shales, while all the
other trap sheets of the State have proved to be intruded bodies.
The copper ores occur above and below these trap rocks.
In Watchung or First Mountain, back of Plainfield, and the contin-
uation of the mountain south and west to Boundbrook and beyond,
the trap is underlain by a stratum of altered shale that is almost con-
tinuously copper bearing. This constitutes the most important cop-
per deposit of the State, one that has been worked at fully 30 dif-
ferent places in former years. The most important development has
been near Somerville, at the American copper mine. The workings
at this place follow down the ore stratum for a distance of 1,350 feet
from the surface, the bed being inclined at an angle of about 10°,
dipping into the mountain. The ore occurs in a well-defined bed, 16
inches to 3 feet thick, lying immediately beneath the trap rock, the
latter rock being also occasionally ore bearing for a few inches next
the contact.
For a distance of nearly 15 miles along the mountain front this con-
tact stratum has p roved copper bearing. The ores consist of the red
oxide of copper with green carbonate and silicate, sheets of native
copper, and rarely peacock copper and glance. In the American
mine the workings pass through the upper oxidized part of the bed,
characterized by the ores just mentioned, into a lower zone in which
they are wanting and in which native copper occurs in small masses
scattered through the ore bed, together with a very little finely dis-
seminated glance, associated with calcite. The native copper occurs
in grains and irregular nodules in bunches of white or grajash-colored
ore irregularly scattered through the purple rock. As no average
sampling was attempted, it may be stated that the systematic sam-
pling of the company's representative is said to have yielded 2^ per
cent copper, a figure which if sustained by mill work will permit of
the profitable working of the property.
At Arlington and many of the other localities of the State the ore
consists of oxide, carbonate, and glance, filling cracks and crevices in
weed] COPPER DEPOSITS OF THE APPALACHIAN STATES. 183
the sandstones above the trap sheets. Reduction works have been
erected at the Arlington property, bordering the Newark meadows,
and at the American mine near Somerville.a
MARYLAND.
The Maryland properties are chiefly of historic interest, as the
shafts and workings of most of the mines are now filled and inacces-
sible. The Liberty mine is a noteworthy exception, and is particu-
larly interesting because it appears to be representative of many, if
not all, of the abandoned properties, and of many undeveloped pros-
pects of the region.
The deposits all occur in an open, gently rolling region underlain
by so-called chloritic schists, whose true nature remains to be deter-
mined. Near the copper deposits thus far examined these rocks
appear to be altered volcanic rocks, probabty rhyolites, and resem-
ble those of South Mountain, Pennsylvania, where copper deposits
also occur. The Maryland ores impregnate these rocks but slightly,
the main ore bodies occurring in what appear to be isolated blocks of
limestone, or rather marble. The ores consist of bornite or peacock
copper, with some chalcopyrite and associated calcite and rhodochro-
site, and it occurs filling crevices, fracture planes, and cementing
together the fragments of a crush-breccia of marble.
VIRGINIA.
Native copper occurs exposed at many localities along the Blue
Ridge region of this State, but no workable mines have been developed
on such properties. Copper sulphides occur, usually with large
quantities of pj^rite, in southwestern Virginia, in Carroll and Randolph
counties; and also in connection with pyrite and native gold in the
old gold mines of the State. Copper ores also occur in the now vigor-
ous^ exploited Virgilina field in Halifax Countj^ though the greater
part of this field lies across the line in North Carolina.
The deposits of native copper and associated oxide and carbonate
ores of the Blue Ridge region prove to be of limited extent, and to
have been derived from the metamorphosed and schistose basaltic
rocks of that region. They have been designated the Catoetin type.
The native metal often occurs in masses of several ounces or even a
pound in weight, and is associated with epidote, quartz, and calcite,
filling small irregular crevices along shear zones in the metamorphosed
igneous rock. Though often traceable for miles by outcrops and
scattered ore masses, the deposits so far explored do not go down
more than 20 to 30 feet from the surface.
The sulphide ores of southwestern Virginia occur beneath iron
"Weed, W. H.. Copper deposits of New Jersey: Ann. Rept. Stale Geologist of New Jersey for
1!M>:J, Trenton, N. J., 1903.
184 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
ore or croppings, constituting what has been called the great Gossan
lode of Virginia, the deposits extending in the same general direction
into North Carolina (Ashe County). These deposits have not yet
been visited, but published descriptions indicate their close resem-
blance to the well-known deposits at Ducktown, Tenn.
The Virgilina deposits consist of native copper in quartz-filled fis-
sure veins traversing andesitic porphyries altered to metamorphic
schists. The ores consist principally of glance occurring in small
bunches and thin lenses and rarely in large ore shoots. Some bornite
also occurs, and this forms the chief ore mineral in the calcite gangue
at the Blue Wing mine, North Carolina. These minerals in decom-
posing have produced the usual green carbonate, silicate, etc., near
the surface of the ground. The character of the quartz indicates that
it is* the filling of an open fissure, but the veins show the lenticular
thinning and thickening characteristic of veins in schistose rock. In
some cases they cross the schistosity at a sharp angle and send short
spurs off into the parting planes. Dikes of massive diabase occur
that are later in age than the schists. These dikes narrow and impov-
erish the veins, but do not interrupt them. The ores are extremely
siliceous, owing to the quartz gangue, hence careful sorting and con-
centrating is necessary before shipment.
NORTH CAROLINA.
This State is rich in copper deposits, I hough lew have been com-
mercially developed. The larger pail of the Virgilina field, whose
veins have just been described, occurs in this State and includes the
Holloway, Bluewing, Durgee, and Person mines, the first named
being a successful producer for many years, the ores going to Norfolk,
where they are smelted with ores brought from Capelton, Quebec.
The most extensive development is, however, at Gold Hill, 12 miles
from Salisbury, N. C. The chief output is from the mine of the
Union Copper Company. The veins show ore shoots of dark gray
and white quartz, carrying chalcopyrite and having a characteristic
gneissoid structure. The veins generally consist of altered schists,
and the inclosing rocks have been classed as Cambrian. These
deposits are closely allied to the pyritic gold deposits of the Carolinas,
which occur for many miles along the border of a large area of erup-
tive granite. The Gold Hill district has been the largest gold-
producing district of the South, the gold occuring in the gossan of
the copper lodes. The veins are lenticular in character, and thicken
and thin rapidly. Although a large amount of money has been spent
on these properties in the last three years and the veins have been
opened for several hundred feet in depth, no definite assurance of
their probable future value can be gotten from the data at hand.
An expensive1 milling and reduction plant has been erected and is in
weed] COPPER DEPOSITS OF THE APPALACHIAN STATES. 185
operation, but the ore proves difficult to dress and very siliceous in
character.
TENNESSEE.
The only copper deposits in Tennessee are the well-known Duck-
town mines, situated in the extreme southeast corner of the State.
These properties were famous for their rich secondary ores half a
century ago, were worked at intervals for thirty years, and are now
in successful operation. The deposits are very large lenticular bodies
of pyrrhotite or pyrite in mica-schists, shown by Kemp to be meta-
morphosed shales. No igneous rocks are known near by, and the rocks
are probably Algonkian. The schists have been broken by disloca-
tions, along which the ores have been deposited, the ore bodies usu-
ally conforming very closely in course and dip to the inclosing schists.
There are two main and parallel lines of fracture. The ore bodies
are huge lenticular masses of sulphides, several of them 100 feet or
more thick. The common ore is a mixture of pyrrhotite and chalco-
pyrite, with calcite, quartz, zoisite, garnet, and in some cases much
actinolite. In some ore bodies pyrite replaces the pyrrhotite wholly
or in part. Much of the ore is shattered and sometimes brecciated,
the chalcopyrite filling the cracks. A second period of shattering
was followed by the formation of coarsely crystalline pyrrhotite, cop-
per p3rrite, and blende. These ore bodies are covered by a gossan
of porous-textured iron ore, consisting of hematite and limonite, pro-
duced by the oxidation of the sulphides, which is mined in large
quantities for iron furnaces. Beneath this gossan occurred the rich
"oxysulphuret " ore, a loosely textured mass of amorphous copper
glance, 0 to 10 feet thick, lying above the unaltered sulphide ore.
This secondary ore is, however, now all extracted, and the copper
contents of the ore bodies being worked averages about 3.5 per cent.
PUBLIC A TTONS ON COPPER.
Brooks, A. H. Reconnaissance from Pyramid Harbor to Eagle City, Alaska.
In Twenty-first Ann. Rept. U. 8. Geol. Survey, Pt. II, pp. 331-391. 1902.
Reconnaissance of a part of the Ketchikan mining district, Alaska.
Professional Paper, U. S. Geol. Survey, No. 1, 116 pp. 1902.
Douglas, J. The metallurgy of copper. In Mineral Resources U. S., 1882,
pp. 257-280. 1883.
The cupola smelting of copper in Arizona. In Mineral Resources U. S.,
1883-84, pp. 397-410. 1885.
Gignoux, J. E. The manufacture of bluestone at the Lyon mill. Dayton,
Nevada. In Mineral Resources U. S., 1882, pp. 297-305. 1883.
Howe, H. M. Copper smelting. Bulletin U. S. Geol. Survey, No. 20-, 107 pp.
1885. [Out of print.]
Irving, R. D. The copper-hearing rocks of Lake Superior. Monograph V,
U. S. Geol. Survey, 464 pp. 1883.
Lindgren, W. The copper deposits of the ': Seven Devils." Idaho. In Mining
and Scientific Press, vol. 78, p. 125. 1899.
Peters, E. D. The roasting of copper ores and furnace products. In Mineral
Resources IT. S., 1882, pp. 280-297. 1883.
The mines and reduction works of Butte City, Montana. In Mineral
Resources IT. S., 1883-84, pp. 374 396. 1885.
Rohn, O. Reconnaissance of the Chitina River and the Skolai Mountains,
Alaska. In Twenty-first Ann. Rept. U. S. Geol. Survey. Pt. II, pp. 398-440.
1901.
Schrader, F. C. Reconnaissance of a part of Prince William Sound and the
Copper River district, Alaska, in 1898. In Twentieth Ann. Rept. IT. S. Geol.
Survey, Pt. VII, pp. 341-423. 1900.
Schrader, F. C, and Spencer, A. C. The geology and mineral resources of a
portion of the Copper River district, Alaska, IT. S. Geol. Survey. 1900.
Vaughan, T. W. The copper mines of Santa Clara Province. Cuba. In Eng.
and Min. Jour., vol. 72, pp. 814-81(5. 1901.
Weed, W. H. Types of copper deposits in the southern United States. In
Trans. Am. Inst. Min. Eng., vol. 30, pp. 449-504. 1901.
Weed, W. H.. and Pirsson, L. V. Geology of the Castle Mountain mining
district, Montana. Bulletin IT. S. Geol. Survey, No. 139, 164 pp. 1896.
186
LEAD AND ZINC.
Extensive investigations in the principal lead- and zinc-mining dis-
tricts of the country have been carried on recently by the United
States Geological Survey. The papers here presented include pre-
liminary reports covering several of these districts. Other references
to lead will be found in several papers in the section on gold and sil-
ver, as all reports on districts in which silver-lead ores were prominent
were included under the precious metals.
ZINC AND LEAD DEPOSITS OF NORTHERN ARKANSAS.
By George I. Adams.
INTRODUCTION.
During the summer of 1002 a party consisting of George I. Adams, of
the United States Geological Survey, assisted by A. II. Purdue, of the
University of Arkansas, and Ernest F. Burchard, was engaged in
the studj7 of the zinc and lead deposits of northern Arkansas. An
extensive report on this field is now in preparation. The following
statement of results and conclusions is made in advance of the final
publication, which will be accompanied by detailed geologic maps
and other illustrations.
POSITION OF THE FIELD.
The lead and zinc deposits of northern Arkansas are in Marion
County and adjacent portions of Boone, Baxter, Newton, and
Searcy counties. Outside of this area there are a few scattered mines,
notably in Sharp and Lawrence counties, The mining development
is north of the Boston Mountains, in what is known as the Ozark
Plateau. The country has a broken surface, as a result of dissection
by streams, and there are numerous exposures of the mineral-bearing
horizons in the valley slopes. This has greatly facilitated prospecting
for the ores.
HISTORY OF THE FIELD.
Lead ore was discovered in northern Arkansas by the early explor-
ers and pioneers, and at first was utilized for rifle bullets. Later it
attracted considerable attention, and in the fifties was smelted in the
187
188 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 2i3.
vicinity of Lead Hill. There was a revival of the industry during
the seventies, but the cost of transportation was so great that it was
practically abandoned.
Zinc ores at first attracted little attention, probably because they
were not so well understood. Before the civil war, however, some
zinc was smelted. In the eighties prospecting for it was carried on
generally throughout the field, andTesulted in finding it at so many
places and so readily accessible that about 1899 there was what might
be called a rush into the field.
PRODUCTION.
From the information contained in published reports and gathered
by inquiry, it lias been estimate^ that the output of the northern
Arkansas district up to and including the year 1900 was 1,500 tons of
zinc ore and 500 tons of lead. In 1901 about 500 tons of zinc were
marketed, and in 1902 about 1,000 tons, or double the amount of the
previous year. The production of lead during L901 and 1902 was
unimportant. There is considerable ore now stored in the bins await-
ing transportation facilities, and the production of the district promises
•to increase during the coming year.
PRESENT DEVELOPMENT.
The condition of the mining industry in northern Arkansas has
been largely governed by transportation facilities. Until recently no
railroad entered the held. In L903 the St. Louis and North Arkansas
Railroad was built to Harrison, and since that time has been extended
to Buffalo River. It is proposed to extend it southeastward, by way
of Marshall, in the direction of Little Rock. The Missouri Pacific is
now building a line in White River Valley from Batesville to Buffalo
City, and it is proposed to extend this line northwestward, by way of
Yellville, into Missouri. The completion of the railroads will afford
facilities for shipping, and mines which have suspended operations
will resume, and others which have attempted no development beyond
prospecting are already erecting mills or determining more definitely
the character of the ground preparatory to doing so.
PROSPECTIVE DEVELOPMENT.
What has been done thus far in the way of mining is not a sat is-
factory test of the field. Some companies which have been organized
have been promoted by men inexperienced in the production of zinc
and lead. The expenditure of money in erecting mills and bringing
in machinery and the failure to market ore at a profit because of the
long wagon hauls have usually resulted in the suspension of operations.
The ore deposits of northern Arkansas are not such as mining men
generally are familiar with, and some have been misled by the results
of the prospecting. The mixed character of the ores found in surface
adams] ZINC AND LEAD DEPOSITS OF NORTHERN ARKANSAS. 189
workings has made it difficult to produce clean concentrates. With
the continuance of deeper workings and the following of the ore bodies
into the hillsides the sulphides are found to predominate, and this
difficulty largely disappears. While it is impossible to predict with
certainty the future of the field, there are mines now opened which
are capable of large output, and many of the prospects are promising
and well warrant fuller exploitation. With the completion of the
railroads the northern Arkansas district promises to assume its true
commercial importance.
GEOLOGY.
The ores are found in two formations, the lower being the Ordo-
vieian dolomites, and the upper the Mississippian limestones. The
Ordovician rocks occur extensively in Baxter County and in the
northeastern part of Marion county, and in the other portions of
the field, along the valleys of the streams, where erosion has cut down
to them. The Mississippian limestones lie to the south and south-
west, forming an irregularly fringed and dissected belt, lying some-
what higher and extending to the base of the Boston escarpment.
The Mississippian limestones formerly extended farther to the north
and northeast and overlaid the Ordovician, but they have been
removed by the wearing away of the land surface through the action
of atmospheric agencies. In addition to these formations, which are
the principal ore-bearing rocks, there are some thin formations found
between the two in certain parts of the field, but for the immediate
discussion of the problems connected with the ore deposits they need
not be described. The Saccharoidal sandstone, however, which lies
above the Ordovician dolomites, and accordingly separates the lower
from the upper ore-bearing rocks, should be mentioned, since it is a
convenient datum in this field. It is known locally as the "sand
ledge," and is referred to in determining the horizons of the mines
and prospects which occur below it in the Ordovician. To the south,
lying upon the Mississippian limestones, and accordingly higher in the
geologic column, are the shales and sandstones, which are extensively
developed in the Boston Mountains.
STRUCTURE.
An examination of the mines of the district shows that the ore
bodies are related to two classes of structure, viz, simple fractures
and breccias. The rocks, considered broadly, are found to be nearly
horizontal. Locally, however, they are undulating, and occasionally
have well-marked dips. There are well-defined normal faults, which
are later than the fracturing and brecciation above mentioned, but,
except in certain instances where fault breccias have been developed,
there is only a minor amount of mineralization along the fault planes
or in the material filling the normal fault fissures.
190 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
The fracturing of the Ordovician rocks was produced by compress-
ive forces, and in certain zones has a considerable vertical extent. A
second and equally important result was brecciation, which was pro-
duced by the differential movement of the strata. The variation in
the structure of the dolomite series, which is in places massively
bedded and in other places thin bedded, laminated, and even shaly,
resulted in the lateral movement being taken up in varying degree
by the individual beds, so that the motion was such as is produced
by forces acting in couples. The brecciation is due to the tendency
of the pieces resulting from the breaking of certain brittle strata to
shear past each other, or to rotate with the horizontal movements of
the adjacent beds, so that the fragments are relatively displaced.
In the Mississippian limestone the compression produced princi-
pally fracturing and Assuring. The walls of the fissures not infre-
quently exhibit slickensiding, which has been produced by the rocks
moving past; each other horizontally. The Mississippian limestones
do not exhibit brecciation, excepting in fracture zones or where they
have been crushed by the dragging of the beds along normal faults,
which in most cases are due to a later adjustment of the rocks of the
area.
The fracturing and brecciation above mentioned are probably due
to stresses induced at the time of the folding in the Ouachita Moun-
tain and Arkansas Valley regions. Al the close of the Carboniferous
period the thick sediments which had accumulated in what is nowcen-
tral Arkansas and western Indian Territory were folded in a manner
which, suggests that they were thrust to the north. In the Ouachita
Mountains there are close folding and thrust faulting; in the Arkan-
sas Valley region open folds. Tn the southern border of the Ozark
region, and particularly in the area here under discussion, the gen-
erally horizontal position of the rocks was retained, but there was
considerable movement of individual beds. This movement was one
of accommodation, and resulted in fracturing without marked dis-
placement. It took place largely along the bedding planes and
resulted in brecciation of the beds. The normal faulting in this area
is of later date, and is probably due to the readjustment following
the crushing, or to subsequent oscillations of level.
Geologic conditions influencing circulation of ground water. — The
rocks which constitute the Ordovician system and the Mississippian
limestones of the northern Arkansas district may be considered as
relatively quite permeable. There are local beds of shale in the
Ordovician through which water would not readily pass, and the
Devonian, which has a very limited extent in the southern part of
the field, is of about the same character and importance in controlling
the path of the ground water. The shales do not have a wide influence,
since they do not form persistent horizons. Where they occur they
probably diverted the solutions laterally, but no localization of ore
deposits seems to be directly due to them.
adams] ZINC AND LEAD DEPOSITS OF NORTHERN ARKANSAS. 191
The shales lying above the Mississippian limestones, on the contrary,
have sufficient thickness to make them an important factor in deter-
mining the movement of ground water. Formerly they extended from
their present boundary, near the base of the Boston Mountains, north-
ward into Missouri, and covered a considerable part of the Ozark
Plateau. Before they were removed they acted as a confining or limit-
ing horizon. Water entering the Ordovician dolomites and Mississip-
pian limestones where they outcropped, and moving southward in the
direction of the dip, was under a hydrostatic pressure beneath these
shales. There may have been a first concentration of the ores, due to
this circulation, and, if so, it could have taken place at some point
between the upper portion of the Mississippian limestones which were
below these shales and the bottom of the Ordovician. This reasoning-
may be appealed to in accounting for the ore bodies now found in the
Mississippian limestones near the base of the Boston Mountains, where
these rocks have recently been uncovered by erosion. It is possible,
however, that the concentration could have occurred through the
agency of lateral circulation adjacent to the fractures in which the ore
bodies are found, without appealing to causes which are of such wide
influence.
As erosion progressed the shales and other formations tying above
the Mississippian limestones were speedily removed from the more
central portion of the Ozark region, so that the conditions which at
first existed, as above outlined, were not long maintained. The main
streams of the region, such as White River and its tributaries, soon
cut through these formations, so that water which may have formerly
been under hydrostatic pressure found issuance in their valleys. At
the present time there are no upper confining shales in the northern
part of the field, and this condition has prevailed for a long period.
The surface water has been free to descend into the Mississippian
limestones and Ordovician rocks, or through the Mississippian lime-
stones into the Ordovician, and the point of issuance of such portions
as have reappeared in the surface flow has been in the valleys of the
larger streams. There, no doubt, has been lateral movement along
bedding planes and through the more permeable strata and open and
brecciated beds and along the surfaces of local shale beds. The Sac-
charoidal sandstone, which is a conspicuous formation and one which
is relatively porous, has probably been a horizon of lateral movement,
assisting in the transfer of the ground water to places where it could
find its way into the adjacent beds.
Relations of belt of weathering and belt of cementation. — Under the
action of atmospheric agencies the rocks at and near the surface suf-
fer loss of their materials and waste away. . This process may be
described as weathering. Deeper in the earth the materials derived
from the upper rocks are largely redeposited. This process is one of
cementation. The belt of weathering and the belt of cementation are
not separated by a sharp line, and, moreover, with the processes of
192 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 218.
erosion the lower limit of the activity of the atmospheric agencies has
constantly migrated downward. These belts are related to the topog-
raphy of the country, the plane separating them being higher in the
hills than in the valleys. Consequently, during the long period which
has been required for the removal of tin' stratified rocks to their pres-
ent limits, there has been a shifting downward and southward, as the
streams have cut their valleys deeper and the escarpments have
retreated southward. In the northern part of the field the belt of
weathering which was formerly in the Mississippian limestones has,
since the removal of these beds, reached the Ordovician rocks. To
the south, as a result of the rugged topography, it lies partly in the
Ordovician and partly in the Mississippian. At the base of the Boston
Mountains, where the the shales a in 1 sand si ones have been but recently
removed, it has descended but a short distance into the upper port ion
of the Mississippian Limestones. The rocks in the northern portion of
the zinc and lead district of northern Arkansas may accordingly be con-
sidered as exhibiting the more advanced stages of the process of
weathering and erosion.
ORE DEPOSITS.
Source of the <>n.s. — It is generally accepted that- the zinc and Lead
deposits of this region have been accumulated by the action of circu-
lating waters which have dissolved the ores which were first broadly
disseminated in the limestones of the region. Water has dissolved
and carried them in solution to certain places where the conditions
were favorable for their redeposil ion. Stating it differently, they
have been derived from the belt of weathering and the belt of cemen-
tation, and largely deposited in the belt of cementation. A study of
the nature of the ores and their gangue materials and of the geologic
history of the region makes it apparent that at least the latest concen-
tration of the ores in the Ordovician has been largely the result of
downward and lateral movements. The metallic sulphides may have
been mainly derived from the Mississippian Limestones, which for-
merly had a wider distribution, from the Ordovician, or from both
formations. An examination of the Mississippian rocks shows that
they have been leached by surface waters. Where they are exposed
in railway cuts they exhibit decay to considerable depths, and within
the area of their outcrop there are numerous sink holes in which the
water disappears into underground channels. The surface cherts
which have been derived from the weatliering of these rocks are fre-
quently porous and spongy, thus indicating the loss of silica. In the
Ordovician secondary silica is not infrequently a gangue of the ores.
The Mississippian limestones contain notable deposits of zinc and
lead at many localities in the Ozark region, and where there is ore in
the Ordovician the Mississippian limestones have formerly overlain
the area. The mines of southwestern Missouri around Joplin are in
adams.3 ZINC AND LEAD DEPOSITS OF NORTHERN ARKANSAS. 193
1 he Mississippian limestones, and in northern Arkansas, as has already
been stated, prospecting has shown that in the portion of the district
where they have been but recently exposed to the action of surface
waters, probably as a result of a first concentration, they carry consid-
erable lead and zinc.
Classification of ore deposits. — The most important deposits of the
district are the sulphide ores of lead and zinc, or, as they are com-
monly called, galena and blende. In the Ordovician dolomites there
are two principal classes of these deposits, which are characterized by
the gangue material. One class is distinguished by the presence of
secondary chert, which occurs as a siliceous replacement of the dolo-
mites, or filling fractures in these rocks; in the other there is asso-
ciated with the ore a large amount of dolomite spar, which forms a
cementing material in the breccias. In certain of the mines there is,
in addition to these main ore bodies, accessory ore which replaces the
country rock to some extent adjacent to the main ore body without
the development of secondary chert or spar.
In the Mississippian limestones the primary ore deposits are accom-
panied by secondary chert and calcite. They are related to fractures,
and in some instances to fault planes. In the latter case they usually
occupy breccias. Accessory ore replacing the country rock is some-
times present with these deposits.
The northern Arkansas field contains important deposits of oxi-
dized ores. These are the carbonates and silicates. They are derived
from the primary sulphides, and are due to the alteration of the sul-
phides by the action of surface waters. In discussing the genesis of
the ores the important problem is the origin of the sulphide deposits,
the relation of the oxidized deposits to the sulphide deposits being
evident.
Processes of primary deposition of sulphide ores. — The action of
ground waters in the belt of weathering, and to a considerable extent
in the belt of cementation, resulted in the solution and transportation
of the ores. As the water percolated downward and moved laterally,
and perhaps later upward, it reached a place where deposition took
place. In the early part of the journey of the waters, through the
action of the carbon dioxide and the humic acids, silica was taken
into solution, and the waters accordingly contained it in notable
quantities, along with the ores in solution. In the later part of the
journey these waters caused the solution of lime and magnesium
carbonate and the deposition of silica and sulphides, the resulting
ores supposedly having been transported as sulphates. The reduction
of the metals to sulphides was probably accomplished through the
agency of organic matter and pyrite in the rocks, directly or indi-
rectly, and deposition of the sulphides occurred along with the
formation of the secondary chert and spar.
The superposition of the original cherts in the Mississippian lime-
Bull. 213—03 13
194 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1002. [bull.213.
stones and the occurrence of the secondary cherts and spar in the
dolomites are entirely in accordance with this theory.
Processes of deposition of oxidized ores. — The oxidized ores of
northern Arkansas are the carbonates and silicates, which have been
derived from the sulphide ore bodies. They are, accordingly, rela-
tively later, and have been produced since erosion has brought the
sulphides into the zone of weathering. The descending waters carry-
ing carbon dioxide have transformed the blende and galena. In some
cases redeposition has taken place immediately, and not infrequently
oxidized ores are found as incrustations on the sulphides. In other
cases they are found along water channels or in the open spaces and
on the surfaces of the country rock. In the exposed faces of ore-
bearing beds and in the upper portions of workings secondary ores
often predominate. When mining operations are carried into the
rocks that are under cover or have been protected from the action of
ground waters, the carbonates and silicates decrease, and galena and
blende are found to be the predominating ores.
Secondary deposition of sulphides. — The sulphide ores which were
dissolved by descending waters have not all been redeposited within
the belt of weathering. Such portions as were retained in solution
upon reaching the belt of cementation were redeposited as sulphides,
the processes in this case being the same as in the primary deposition
and the ore bodies belonging to a second generation. In the lower
horizons of the Ordovician dolomites considerable zinc ore is found
which occurs as bright, clean crystals associated with drusy quartz
or in openings formed by fracture. Such deposits are usually lean,
and thus far no workable body of ore of this nature has been
discovered.
Observations have not shown that there is a criterion for clearly
distinguishing the secondary sulphide ores, which may have origi-
nated by migration from the primary deposits, since it is not improb-
able that the solutions at the time of the first concentration may have
deposited most of their ore in the upper horizons, in which case the
deeper deposits would have the characteristics above described and
assigned to the ores of the second generation.
Sulphide deposits associated with secondary chert. — Where chert is
the principal gangue of the blende and galena, deposition in the
Ordovician has taken place by the replacement of the dolomites and
the filling of fracture spaces and cementation of breccias. Secondary
chert when freshly exposed usually has a bluish color. It may be
distinguished from the other country rocks by means of its hardness,
since it can not be scratched with a knife. It frequently has a banded
or bedded appearance, which corresponds to the bedding of the orig-
inal dolomite, and crystals of ore usually well formed and distinct
occur within the mass. In case some of the sulphides have been
leached out, molds of the blende are seen, which give the chert a
adams] ZINC AND LEAD DEPOSITS OF NORTHERN ARKANSAS. 11)5
honeycombed appearance. The richer deposits appear to be related
to fracture zones, and occur along the fissures and replacing the
adjacent rocks. The path of the ore-bearing solutions in descending
has apparently been along fractures and laterally along the bedding
planes, and the mineralization decreases away from the fracture zone.
Sulphide deposits in bedded breccias. — In the brecciated beds of the
Ordovician dolomites the open spaces between the fragments have
afforded channels for the ore-bearing solutions, and the precipitation
of the sulphides and dolomite or pink spar has usually taken place
without the dissolving of the country rock to any appreciable extent.
The pink spar is not always accompanied by ore. The sulphides have
been deposited in a somewhat local way, many factors being con-
cerned. Not infrequently, in prospecting, breccias containing pink
spar and but little ore are found; and, where the breccias are ore bear-
ing, when they are followed for a considerable distance they usually
show a decrease in the amount of ore.
Sulphide deposits in fissures. — In the Mississippian limestones most
of the mines and prospects are related to fissures, the ore occurring
in material filling the fissures or in the fissure and the openings adja-
cent to it. These deposits differ from those in the fractured dolomites
in being more clearly defined. The gangue is usually secondary chert
and calcite. The walls of the fissures exhibit slickensiding, as a
result of the movement of beds, and frequently indicate displacement
in a horizontal direction.
Sulphide deposits in fault breccias. — Where the Mississippian lime-
stones have been displaced by normal faulting and the rocks have
been dragged, they not infrequently exhibit brecciation. The angular
fragments are largely primary chert, and the ore occurs associated
with a calcareous and siliceous matrix which cements the breccia.
Sulphide ore in country rock. — In many of the mines and prospects
the country rock has not been mineralized. In other cases, for a
short distance adjacent to fissures, fractures, and water channels, the
ore-bearing solutions have formed what is here called accessory ore.
The action in this case has been one of replacement. The country
rock exhibits recrystallization and carries small crystals of ore.
Where accessory ore is found the main ore body is usually rich, and
there is a suggestion that deposition in the country rock resulted
because of the large amount of ore in solution at these places. In the
northern Arkansas district the scattered crystals of blende in the
country rock are spoken of as disseminated ore. This term, unfortu-
nately, is not quite appropriate, and, accordingly, the word accessory
is suggested, since it does not imply the mode of deposition usually
ascribed to disseminated ores. Accessory ore, inasmuch as it is usu-
ally found associated with rich ore bodies, is looked upon by the pros-
pectors as a favorable indication. The ore in secondary chert is not
included under this head.
196 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [BULii.213.
Ore associated with quartz druses.— Not infrequently, in the Ordo-
vician dolomites, the lower ore horizons exhibit quartz druses and
surfaces covered with minute quartz crystals. The ore in these rocks
occurs as clean, bright crystals deposited on the quartz. It seldom is
found in large masses, but is generally distributed through the rocks.
The probability is that it represents a migration from the higher
horizons, but it is possible that it was deposited from the depleted
solutions at the time of primary deposition.
Opinions of previous writers.0 — In the previous reports on the
northern Arkansas field certain ideas have been advanced which are
not accepted by the writer. These largely pertain to theoretical con-
siderations, although some of them deal with the geologic facts.
There is no opportunity in this article for a discussion of the differ-
ences of opinion which have arisen, but it is thought best to mention
certain points which are obvious from a review of the literature.
The writer has argued that the bedded breccias were produced by
the movement of strata past one another, as a result of compressive
forces. Mi'. Branner, in speaking of the breccias, states that the
bedded breccias were not formed on fractures, but along ancient
underground water courses. The breccia deposits which Mr. Bain
described were considered by him to have been formed along zones of
pressure. He speaks of limestone conglomerates, which, in the opinion
of the present writer, are in reality breccias. The relation of these
so-called conglomerates to the brecciated beds, and the extensive
brecciation due to differential horizontal movement, do not seem to
have been recognized by Mr. Bain.
In regard to the faulting of the region, the writer presents an inter-
pretation which is decidedly opposed to that of Mr. Branner. lie con-
siders certain of the most important faults, some of which were
described and figured by Mr. Branner as thrust faults, to be normal
faults.
In regard to the theory of ore deposition, all the differences can not
be here pointed out. However, Mr. Branner described bedded
deposits contemporaneous with the rocks in which they occur. Such
ore bodies are believed by the writer to be the result of secondary
alteration and replacement. Mr. ]>ain has given considerable promi-
nence to what he calls disseminated ores in compact limestone and
unbroken conglomerate. This description does not seem to be a cor-
rect characterization of any of the main ore bodies of the district,
a Branner, J. C, Zinc and lead deposits of northern Arkansas: Ann. Rept. Arkansas Geol. Sur-
vey for 1892 (published in 1900), Vol. V; also Trans. Am. Inst. Min. Engrs., Vol. XXXI, p. 572.
Bain, H. F., Preliminary report on the lead and zinc deposits of the Ozark region: Twenty-second
Ann. Rept. U. S. Geol. Survey, Pt. II, 1902, pp. 195-202. Van Hise, C. R., and Bain, H. F., Lead and
zinc deposits of the Mississippi Valley, read before the Institution of Mining Engineers at the
general meeting at London, May 29, 1902: Excerpt from Trans. Inst. Min. Engrs., pp. 34, 35.
LEAD AND ZINC DEPOSITS OF THE JOPLIN DISTRICT,
MISSOURI-KANSAS."
By W. S. Tangier Smith.
INTRODUCTION.
The lead and zinc deposits of the Mississippi Valley have been
divided into three groups, those of (1) the Ozark region, (2) the Upper
Mississippi Valley, (3) outlying districts. Of these the most impor-
tant is the Ozark region, which extends from the Arkansas River on
the south to the Missouri River on the north and from eastern Kansas
on the west to the Mississippi River on the east. It contains four
districts, (1) the Southeastern Missouri district, (2) the Central .Mis-
souri district, (3) the Missouri-Kansas or Southwestern Missouri dis-
trict, (4) the Northern Arkansas district.
LOCATION AND TOPOGRAPHY.
The Joplin subdistrict, as considered in this paper, includes that part
of the Missouri-Kansas district lying along its western margin and
between 04° 15' and 94° 45' west longitude and 37° and 37° 15' north
latitude. While thus embracing an area of only 47G square miles, it
produces more zinc than all the other districts of the Mississippi Val-
ley combined, and is in fact the most important zinc-producing dis-
trict of the United States. Tu addition to the zinc, it produces a smaller
though still considerable amount of lead. In the year 1002 the lead
production of the district was about 12 per cent of its zinc production,
the latter being 223,337 tons.
About three-fourths of the Joplin district is in Missouri, and includes
among its larger towns Joplin, Webb City, Carterville, and Carthage.
The remaining one-fourth (except for a fraction of a square mile fall-
ing in Indian Territory) is in Kansas, and its largest towns are Galena,
Empire, and Baxter Springs.
The Joplin district lies on the western margin of the Ozark uplift,
and its upland surface is almost flat, with a low general slope to the
northwest. These level uplands are cut by numerous stream valleys,
for the most part open and rather shallow. The courses of many of
"A more extended article, of which this i>aper is an abstract, is in course of preparation for
Survey publication.
197
198 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
&
the smaller streams are determined bylines of shale deposits, alon
zones of faulting and consequently lines of weakness. As the shales
are the softest rocks of the region, there is thus a double reason for
the correspondence of the valleys with these lines, and probably the
same facts explain the general limitation of mining to the valleys and
their slopes.
GEOLOGY.
Stratigraphy. — The geology of the district is simple. The rocks
are wholly sedimentary, and those exposed on the surface are all of
Carboniferous age, both Upper and Lower Carboniferous being repre-
sented. The Lower Carboniferous rocks consist of about 350 feet of
cherts and limestones in varying proportions. This is the ore-bearing
formation of the district, the ore occurring especially in the more
cherty portions. The limestone is generally nonmagnesian, but a
comparatively small amount of dolomite occurs, mainly as the result
of alteration of the limestone at the time of the deposition of the ores.
The limestone generally contains a considerable amount of organic
matter, evidenced by I lie vaseline-like odor which is characteristic of
the rock when broken; and occurrences of bitumen are common,
especially in association with the mineral deposits. Not far from the
top of the series is a thin but persistent bed of oolite, outcrops of
which occur over the entire district. Some distance below is a heavj^
bed of chert, about 50 feet thick, known as the Grand Falls chert.
The Lower Carboniferous rocks are exposed over the greater part
of the Joplin district. Above them, when not eroded, lie the Upper
Carboniferous Coal Measure shales and sandstones. The shales,
which constitute the greater part of the Coal Measure expos ures of
the quadrangle, are frequently associated with thin beds of coal.
The sandstone occurring with these shales is sometimes changed to
a quartzite through the infiltration of secondary silica. There is a
considerable area of these shales and sandstones in the northwest
corner of the quadrangle, in addition to small patches of shale over the
entire district. These smaller occurrences in some cases represent
outlying hills left on the removal of the Coal Measure rocks; in other
cases their persistence is due to their occurrence in pre-Coal Measure
erosion basins, or in later basins formed by the folding of the rocks,
while in still others they are the result of faulting.
Beneath the Lower Carboniferous limestones and cherts is the
Devono-Carboniferous shale. The occurrence of. this formation in
the Joplin district has not been proved, though it is believed to be
present as a thin bed of shaly limestone having an average thickness
of only a few feet. The Cambro-Silurian rocks beneath the Devono-
Carboniferous shale consist of a series of magnesian limestones,
dolomites, and sandstones. As none of the rocks below the Lower
Carboniferous are exposed in this district, their occurrence can be
determined only from deep borings.
smith. 1 LEAD AND ZINC OF JOPLIN DISTRICT. 199
Structure. — The rocks of the district have a low general dip to the
northwest at an angle somewhat greater than the general inclination
of the surface. Open folding' is common, both on a large and small
scale. Noticeable faulting is not common over the quadrangle as 'a
whole, though small slips occur here and there. In those parts of the
district, however, where ore deposits occur, faulting and folding are
both of more importance, but even here the amount of faulting, as
a role, is not great. Both normal and reversed faults are found,
both being the result of readjustment due to compression stresses.
Where cherts predominate, brecciation has developed as a result of
the faulting and folding. The individual faults are not known to
continue for any considerable distance, but they occur (as do the
folds also) mainty in zones. The ore deposits follow these zones of
faulting and folding, and frequently come in and die out with the
faults with which they are associated. The occur rence of cross folding
and faulting, at an angle with the main lines, tends to make the zones
of brecciated rocks more complex. As a result the deposits are, on
the whole, extremely irregular. In at least one part of the district
there is well-defined evidence of two periods of movement accom-
panied by fracturing and faulting -of the rocks, both periods having
been followed by ore deposition.
In connection witli the phenomena of folding and faulting, shear
zones and joints of compression and tension have been extensively
developed, mainly in the cherts. Adjustments of small amount, also,
have taken place along the bedding planes. The effects of these dif-
ferent movements vary with the rocks. The shales have yielded to
stresses by folding or by faulting; the limestones by folding and fault-
ing with occasional complex fracturing. Stresses in the cherts, which
are generally extremely brittle, are nearly always relieved by fractur-
ing, more or less complex, and by brecciation, though occasionally by
flexure. Many of the cherts are so brittle that only a slight amount
of movement is necessary to cause complete brecciation, simple fold-
ing being frequently sufficient. The brecciated cherts are often more
or less firmly recemented, sometimes by a black secondary chert fre-
quently containing disseminated sphalerite; sometimes by free sphal-
erite or calcite, or by both. In many cases the cherts are thoroughly
crushed, while still showing their original bedding planes. Examples
have been noted of heavy-bedded cherts which have been cut by joint
planes in several directions, the loosening of the mass by slight fault-
ing or other cause giving rise to "bowldery ground" such as is char-
acteristic of many of the mines. It is probable also that, during fold-
ing, arching of the cherts occurred in some places, and that later, in
many instances after the spaces had been filled with the material
which now appears as the black secondary chert, the arches were
broken down. It is mainly in the brecciated cherts that the ore
bodies occur.
200 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
ORE DEPOSITS.
Minerals. — The principal minerals of the Joplin district are sphal-
erite (locally called "jack"), galena ("lead"), calcite ("tiff"), dolomite
("spar"), marcasite and pyrite, mainly the former (both called "mnn-
dic"), chalcopyrite ("copper"), cerussite and anglesite (both known
as "drjr-bone"), calamine ("silicate"), and smithsonite. Calamine
and smithsonite have generally been confused in this district, and
most of the smithsonite, which in reality occurs more frequently than
has been heretofore supposed, has been mined as "silicate."
Distribution of ores and minerals. — Of the lead and zinc ores the
sulphides, sphalerite and galena, occur for the most part below the
level of underground water; the sulphate and carbonate of lead and
the carbonate and silicate of zinc, being all oxidation products of the
sulphide ores, occur mainly above that level, together with the more
or less oxidized gangue and country rock. The deposits below ground-
water level represent the concentrated ores, both those of first con-
centration and those of secondary enrichment. They are frequently
associated with more or less marcasite or pyrite, though these are as a
rule inconsiderable in amount. In these deposits the galena is usually
found at the upper levels (except in sheet ground, described here-
after) tilling fractures in broken or brecciated cherts, and usually
associated with more or less sphalerite. Only sphalerite (frequently
with some iron sulphide) is found at the lower levels. It occurs (1)
as a cement in chert breccia; and (2) disseminated in a black, second-
ary chert which cements the brecciated cherts and also occurs in
lenticular bodies along the bedding planes in sheet ground. Sphaler-
ite is also found in small quantities disseminated in shale, in selvage,
in mud, in limestone, or in dolomite.
To sum up, the vertical distribution of the ores shows:
First. Above underground water level, galena and occasionally
some sphalerite; also the oxidation products, the carbonate and sul-
phate of le;ad and the carbonate and silicate of zinc.
Second. Below underground water level, the sulphide zone. Some-
times, but not always, galena dominates in the upper part of this
zone, with sphalerite dominant in the lower and greater part of the
zone. This succession does not always hold, and some mines have
yielded mainly galena throughout, while mines yielding sphalerite
with little or no galena are common. In the typical sheet ground
galena and sphalerite usually occur together and associated with
marcasite.
Forms of ore deposits. — In considering the forms assumed by the ore
deposits, the ore bodies in the mines of this district may be roughly
divided into two classes, (1) horizontal or nearly horizontal deposits;
and (2) vertical or inclined deposits. The first class includes the
tabular bodies of ore known as blanket veins or sheet ground. Depos-
its belonging to this class are mainly limited in occurrence to a belt
smith,] LEAD AND ZINC OP JOPLIN DISTRICT. 201
extending from the town of Duenweg northwesterly between Webb
City and Carterville to Oronogo. They reach their greatest develop-
ment south and southeast of Carterville. The rocks in which the ore
occurs are bedded cherts, horizontal or nearly so. The ore is found
mainly along the bedding planes, though it also occurs in seams in
the somewhat broken beds. Much of that occurring along the bedding
planes is disseminated in a dark secondary chert which appears to
fill cavities left by the removal through solution of limestone lenses.
The ore is mainly sphalerite, with a minor proportion of galena, and
a still smaller amount of marcasite. Deposits of this form are always
near ore bodies belonging to the second class.
The latter may be divided into (1) linear deposits (runs), (2) circu-
lar or elliptical deposits, and (3) irregular deposits. The linear depos-
its consist of comparatively narrow bodies of ore, either vertical or
inclined, following a roughty uniform direction. The ore is as a rule
mainly or wholly sphalerite; where it is associated with galena the
latter occurs usually in the upper part of the deposit. The sphalerite
is found both disseminated., for the most part in a dark secondary
chert matrix or in selvage, and cementing chert breccia or lining
interstices of the breccia or solution cavities in limestone or dolomite.
It is often associated with calcite and pink dolomite. The rocks in
which the ore occurs are generally brecciated cherts which have been
recemented to a greater or less extent, either with black secondary
chert or with calcite, sphalerite, dolomite, or galena, either separately
or in combinations of two or more. In the vicinity of Joplin this brec-
cia with its ore occurs almost without exception against a barren wall
of chert and limestone, the latter altered to a coarse-grained gray
dolomite, apparently closely connected with the deposition of the
sphalerite. In these same deposits galena, where it occurs, is usually
found tilling cracks in the fractured cherts, near the upper limits of
the sphalerite and for the most part near its outer margin, i. e., away
from the dolomite.
The chert breccias in which the linear deposits occur are due largely,
to faulting, though to a minor extent developed by folding. Breccias
produced by folding may be associated with those resulting from
faulting. The ores in the former occur, as a rule, along the flanks of
the folds. Where two faults meeting at an angle have developed at
the same time, the brecciation, with its accompanying deposit, formed
along one fault, instead of crossing the other fault at the point of
meeting, may take the direction of the intersecting fault, thus forming
one continuous deposit; and the two faults, instead of meeting at an
angle, may be joined by a curve. Such deposits are closely related
in manner of formation to the deposits of the following type.
Circular or elliptical deposits are a modification of the Linear deposit.
A horizontal section of these ore bodies would have the form of a
roughly circular or elliptical ring, inclosing a central barren "core."
202 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213;
The deposit as a whole has roughly the form of either a truncated
cone or a dome, both types being commonly associated with an irreg-
ularly circular or elliptical area of shale at the surface, over this
central portion. The ores of the circles arc4 similar in character to
those described under linear deposits. In all the important cases
studied, the circle has been formed by the intersection of faults.
Small circular deposits are sometimes developed on the flanks of a
dome produced by folding. In all the circular deposits near the city
of Joplin which were examined, the inner walls were of the dolomitized
limestone with chert.
The vertical extent of the ore body, in both linear and circular
deposits, may be limited to a few feet or it may continue for a hundred
feet or more. The occurrence of the ore is not confined to a particular
horizon, but it may be met at any level where the conditions were
favorable for Ms deposition, and it maybe found at several levels,
one above another, with barren or nearly barren ground between.
Under the head of irregular deposits may be included all such ore
bodies as do not correspond to any of the foregoing types. They are
formed in breccias due either to complex folding or faulting, or to
folding combined with faulting, and have no definite form. They
may in most cases be considered as combinations of types already
described.
Individual runs of ore, associated with one or more faults or folds,
may have a horizontal extent ranging from a few feet to one-fourth
mile or more. Although there are areas in which no systematic
arrangement of the individual ore bodies can be discerned, in most
cases they can be grouped along a zone of faulting or folding, within
which they mayor ma\ not show a general Linear or parallel arrange-
ment; or the main lines parallel to the general direction of the zone
m;i\ be associated with minor lines a1 an angle with it. Such zones
usually have the same general trend as the main system of faulting
for the part of the district in which they occur. There are several
important systems of faults and folds in the Joplin district which
vary somewhat in direction from place to place, and of which the
most prominent throughout the district has a general northerly or
northwesterly trend. A second important system having a general
easterly or northeasterly direction sometimes predominates, though it
is usually associated with the other and subordinate to it.
The principal structural disturbances of the Joplin district appear
to have been concentrated along certain lines or belts having the
same general trend as the more pronounced zones of ore deposits,
which group themselves roughly along these belts. The three main
belts of the district are (1) the Jojuin belt, including the zones imme-
diately around Joplin and northward to Tuckahoe, with the outlying
groups southward to Shoal Creek and northwesterly to Carl Junction;
(2) the Galena belt, including the deposits around Galena and just
smith. I LEAD AND ZINC OF JOPLIN DISTRICT. 203
north and south of it; (3) the Webb City belt, including the mining
zones from south of Duenweg northwesterly between Webb City and
Carterville to Oronogo and beyond. Of these the Joplin belt is char-
acterized b}^ the common association of the sphalerite with dolomitized
limestone (as already noted), while in the Galena and Webb City belts
dolomite is of comparatively rare occurrence. The latter belt is char-
acterized by extensive sheet deposits which are either entirely absent
or unimportant in the other belts. Around Joplin itself the breccias
on the east side of the town are cemented mainly with calcite, and
black secondary chert is not common, while on the west side of the
city black chert is common, and in places forms the far larger propor-
tion of the cement of the brecciated cherts.
Deposition of ores. — In this district as elsewhere, the conditions
governing ore deposition are partly physical and partly chemical.
The physical conditions are those governing the circulation of under-
ground waters in general; the chemical conditions are more complex,
and as yet are only partly understood. Lead and zinc sulphides are
known to be widely distributed in minute quantities in both the Car-
boniferous and Cambro-Silurian rocks. The underground circula-
tion probably takes lead and zinc sulphide from all the rocks where
conditions are favorable to oxidation and solution, tending to concen-
trate the ores as sulphides wherever favorable conditions for this
process are met. The lead- and zinc-bearing waters come from both
the Carboniferous and Cambro-Silurian rocks, and entering at the
surface east of the Joplin district, they have flowed and still flow
down the dip of the rocks. Reaching the Joplin district they meet
conditions favorable to primary concentration, and the ores are
deposited. It is believed that such deposition is still taking place, as
it has done in the past.
As the waters which give rise to the primary concentration flow
down the dip of the rocks their motion is partly descending until the
Joplin district is reached. There the waters coming from the Car-
boniferous rocks have, on the whole, a lateral motion, while those
bringing lead and zinc from the Cambro-Silurian into the Carbonifer-
ous rocks are, on the whole, ascending. The direction of flow of the
underground waters is not in general a fixed factor in ore deposition,
but solution and redeposition of ores may take place in waters having
either an ascending, descending, or lateral motion, provided other
conditions are favorable to oxidation and solution at one point and to
reduction and precipitation at another.
Although this i>rocess of primary concentration is still effective, it
was far more important when the entire district was covered with the
comparatively impervious Coal Measure shales, and the conditions were
more favorable than now to an artesian circulation. When erosion had
largely removed this covering from the district, and had brought many
of the ore deposits near or quite to the surface, within the reach of the
204 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
doAvmward-inoving waters containing oxygen, the ores became oxidized
to sulphates. The sulphate of lead (anglesite) underwent further
alteration to the carbonate (cerussite). The sulphate of zinc, react-
ing with the limestone or with the secondary chert which contained
the ores, replaced the former with smithsonite and the latter, in part
at least, with calamine, which also filled small cavities in the rocks.
As the galena is less easily oxidized than the sphalerite, and its oxida-
tion products are less soluble, the oxidized lead products are gener-
ally found nearer the surface than those of zinc. The oxidized zinc
ores extend generally from the surface, or close to it, downward to a
short distance below ground-water level. In all observed cases the
oxidized products have been deposited close to the place of original
sulphide concentration, and are associated with secondary chert
leached of its formerly contained sphalerite — the honeycomb rock of
the miners.
During the process of oxidation, carbonation, or silicification of the
ores some of the products of oxidation of the sulphides were carried
in solution below the level of underground water, where the}7 were
redeposited as sulphides. Gradually, also, the oxidation products
deposited above ground-water level were taken into solution by sur-
face waters and carried downward and redeposited in the same way.
These sulphides, together with those of primary concentration, form
an enriched /one, which is greatest not far below the level of under-
ground water, and decreases downward. In the Joplin district the
enrichment of the sulphide ores has resulted not in a better grade of
the ore already existing, bu1 in an increase in the quantity of the ore
of 1 he enriched /one. The lead sulphide is deposited at the highest
levels, together with more or less sphalerite, and decreases in amount
downward, while the sphalerite increases, so that in depth the latter
dominates. Pyrite and marcasite are relatively unimportant in the
Joplin district, and il can not be stated definitely that, they are more
abundant, on the whole, at one level than at another.
Where ores of secondary enrichment have been brought near the
surface by the wearing down of the land through erosion, they would
be acted on in the same way as ores of primary concentration, and
would be again concentrated below ground-water level. As the
Joplin district, however, has been so little eroded since the removal
of the Coal Measure shales, it is believed that this concentration of
enriched ores is of little importance.
LEAD, ZINC, AND FLUORSPAR DEPOSITS OF WESTERN KEN-
TUCKY.
By E. O. Ulrich and W. S. Tangier Smith.
GEOLOGY AND GENERAL RELATIONS.
By E. O. Ulkich.
INTRODUCTION.
During the summer and fall of 11)02 a party consisting of the writer
and Dr. W. S. Tangier Smith, with two field assistants, Messrs. A. F.
Crider and F. Julius Fohs, was engaged in an extended investigation
of the zinc, lead, and other valuable mineral deposits of western
Kentucky and, in less detail, of those occurring on the northern side
of the Ohio River in Pope and Hardin counties, 111. The latter
counties, together with the counties of Crittenden, Livingston, Cald-
well, and adjacent portions of Christian, Trigg, and Lyon, in Ken-
tucky, are embraced in a lead and zinc district differing in several
respects from the other lead and zinc districts of the Mississippi
Valley. This district differs from the others in the presence of basic
igneous dikes, in the ores -occurring principally along fault lines in
true fissure veins, and, finalty, in having the lead and zinc ores almost
invariably associated with fluorite, the latter as a rule forming the
most abundant gangue mineral.
The recent work in western Kentucky consisted largely in the
verification and correction of the mostly unpublished results of a
study of the geology of the three counties of Caldwell, Crittenden,
and Livingston carried on by the writer in 1889 and 1890, while a
member of the geological survey of Kentucky. The developments of
the past decade permitted us to add many new observations and to
advance the geologic knowledge of the district to a point where it is
possible to describe the ore deposits and the systems of fractures and
faults in and along which they occur as well as the geologic forma-
tions and their geographic distribution in considerable detail. The
following brief statement, however, is to be viewed merely as an
advance publication of results and conclusions that will be more fully
described, and will be illustrated, in a report now in preparation.
205
200 CONTKTBUTIONS TO ECONOMIC GEOLOGY, 1902. [Sull.213.
DEVELOPMENT.
History. — The ore deposits of this district have been known to
settlers since early in the last century. The first attempt to mine
them was made by a company headed by President Andrew Jackson.
The operations of this company were carried on in Crittenden County,
Ky., their shaft being sunk on the Eureka vein within 100 yards of
the present main shaft of the Columbia mine. Between that time and
the beginning of the civil war other equally primitive attempts were
made to mine the ore deposits, most of them in Livingston County,
notably at the Royal mines near Smithland.
With the general resumption of mining activities in the seventies,
and especially in the later years of that decade, when some excite-
ment was evoked by the successful operations at Rosiclaire, on the
Illinois side of the Ohio River, work was resumed at several of the
mines in western Kentucky. Considerable activity, indeed, was
shown in the development of the Columbia mines, in Crittenden
County. In 1878, however, nearly all mining operations in the dis-
trict ceased, because the market value of lead, which up to that time
was the only mineral sought here, dropped to so low a figure that
with the lack of transportation facilities mining operations became
unprofitable.
The demand for American fluorspar which set in at about this time
served to maintain a small degree of interest in mining in the south-
ern portion of the district, but only for a few years, when the same
lack of cheap transportation and a slight drop in the value of the
product rendered the otherwise equally good Kentucky mines incap-
able of compet ing with the more fori unately situated Rosiclaire mines.
In the last live or six years interest in the district has again revived,
and, for the first time in its history, the numerous veins and mines
are being systematically prospected and developed.
Production. — It is impossible now to make any satisfactory state-
ment concerning the output of the mines of the district prior to 1899,
but it doubtless amounted to a thousand or more tons of lead and
many times that amount of fluorspar. Estimates of the production
of the Illinois mines were not secured, but those in Kentucky pro-
duced, according to statements of shippers, about as follows: Fluor-
spar, 1899, about 5,000 tons; 1900, 10,500 tons; 1901, 1:3,700 tons, and
the first seven months of 1902, 12,000 tons. Zinc carbonate, 1901,
1,136 tons; first seven months of 1902, about 2,450 tons. The produc-
tion of lead was insignificant, chiefly because the mines in which
galena is an important or predominating ore have only recently
resumed operations or are awaiting improved transportation. The
present year, however, promises to see a notable increase in the pro-
duction not only of lead but also of zinc, and a smaller increase. in the
output of fluorspar.
Prospective development.— The mining operations so far carried on
in the district can not be considered as a satisfactory test of its possi-
ULRKH] LEAD, ZINC, AND FLUORSPAR OF WESTERN KENTUCKY. 207
Abilities. It seems probable, however, that a field containing mines
that at various times were operated with profit for the lead ore alone,
the zinc ores and fluorspar being left on the dump, should under
economic and competent modern management become a producer of
some importance. Two obstacles stand in the way at present. The
first is a lack of a cheap and thorough method of separating the fine-
grained sphalerite from the fluorspar with which it is almost invaria-
bly associated. Now that the need of such a process is emphasized,
it is possible that a satisfactory method will be discovered before the
second impediment — lack of transportation — can be overcome. Many
men are working on the problem and already several promising if not
wholly satisfactory processes have been patented. A plant to do this
work has just been completed in Paducah and another is being erected
in St. Louis, while a third process is being perfected at a plant near
Salem, Ky.
The second difficulty in the way of the development of the district
is one common to all new fields, namely, a lack of transportation
facilities. The roads throughout the district are almost without
exception very bad, rendering successful mining where the wagon
haul exceeds 5 miles impossible. Fully two-thirds of the entire dis-
trict lies more than that distance from the lines of the Illinois Central
Railroad which traverse it. However, two navigable rivers, the Ohio
and the Cumberland, are being used in a small way, and this cheap
mode of shipment will doubtless exert a considerable influence on the
development of the field.
GEOLOGY.
Stratigraphy. — The geologic formations exposed at the surface or
penetrated in mining in the area under consideration are all of Car-
boniferous age, the lowest being the St. Louis limestone of the Missis-
sippian series, while the highest contains the two lower coal beds of the
Coal Measures and is confined to the eastern and northern edge of the
district. These lower Coal Measures constitute the western border of
the western Kentucky coal basin, which extends into the district from
the east and north. As is proved by outliers, remaining chiefly
because they crown blocks thrown down in the faulting of the region,
this border once extended much beyond its present limits, the basal
Coal Measures perhaps having originally covered the whole of the
area. The base of the Coal Measures or Pennsylvanian series is here
always formed by a coarse brown sandstone containing more or less
abundant quartz pebbles. Immediately beneath this come the sand-
stones, shales, and limestones of the Chester group, the rapidly alter-
nating beds of which have a total thickness of about GOO feet. Next
beneath and intervening between the base of the Chester and the top
of the St. Louis limestone is the Princeton limestone, 200 to 250 feet
thick, which is light-gray and compact and includes more or less shale
in its upper third, and more massive, oolitic, and light-gray or nearly
white in its lower two-thirds. Between these two divisions of the
208 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 3902. [bull. 213.
Princeton there is a very persistent layer of calcareous sandstone,
varying- from 1 to 12 feet in thickness.
The St. Louis limestone underlying the Princeton limestone has a
thickness of about 500 feet. Its basal portion is also oolitic, but of a
darker color than the Princeton oolites. The remainder consists of
dark-gray, highly siliceous limestone, the silica of which, on the
weathering and decomposition of the limestone, to which it is more
readily subject than the other limestones, is concentrated into nodular
masses of flinty chert varying from 2 to 8 inches in thickness. These
rounded lumps often occur in great abundance and are highly charac-
teristic of the formation. Decomposition of t^he St. Louis limestone
is always deep, sometimes extending to a depth of 50 feet beneath the
surface, so that the limestone itself is rarely seen except along rapidly
eroding si reams. ( )wing to complex faulting the area! distribution of
these formations is very irregular and patchy.
Beneath the St. Louis limestone there is an even more' siliceous and
earthy limestone, representing the Tullahoma formation and Port
Payne chert of the south, the Keokuk and Burlington limestones of
western Illinois, and the Boone chert of Missouri and Arkansas. This
horizon holds mosl of the zinc and lead deposits of the Joplin district
and some of the deposits found in northern Arkansas. Whether it is
ore bearing in this district or not can only be determined by sinking
on the veins to its horizon.
Structure. — The most marked structural feature of the district is an
extensive series of fractures, nearly all of which are accompanied by
more or less faulting. All available evidence tends to the conclusion
that vein deposits of some kind occur in all the fractures where either
one oi' both walls are limestone, excepting where the fractures are
occupied by peridotite dikes. These usually are accompanied by
only a slight displacement of the strata, and, with a single known,
but very notable, exception, are not associated with valuable minerals.
It is a fact that nearly all the mines of the district whose value
has been proved by development, and nearly all the promising pros-
pects, have either the St. Louis or the Princeton limestone on one or
both sides of the fracture. As to the few exceptions where a promis-
ing prospect occurs in a Chester area, in every case known to me one
of the limestone beds of that group of rocks forms either the hanging
or the foot wall of the fissure. We have met with several cases in
the district that might appear to be exceptions to this rule, notably
the Clements mine on the Crittenden Springs property, and the east-
ernmost shaft of the Tabb mines. Critically examined, however, the
exceptions prove to be more apparent than real, since in the first of
these cases one of the walls of the adjacent main fault is the Prince-
ton limestone, and in the other the St. Louis limestone, the openings in
question being driven in fissures running parallel with and sudsidiary
to the main faults. These subsidiary fissures were probably formed
by large slices of country rock breaking away from the hanging wall,
ihuidi.] LEAD, ZINC, AND FLUOKSPAK OF WESTERN KENTUCKY. 209
wliich is usually jointed parallel with the fault plane. If this is true
then the two fissures should unite at some distance beneath the
surface.
There are at least 30 faults in the district, with maximum dis-
placements of from 400 to 1,400 feet, and traceable for distances of
from 2 to 20 miles or more. Since many of these are connected with a
series of subsidiary fractures and faults, whose displacement rarely
exceeds 200 feet, they may be distinguished as the main 'faults. Of
the subsidiary fissures, there are probably hundreds, and it is the
belief of the writer that many of them will prove more productive,
for equal lengths, than the veins in the main faults.
As a rule the fault lines are practically straight, apparent slight
deflections in the course being generally due chiefly to the dip of fault
planes, which is usually considerable, upon the line of outcrop over
the undulating surface. Occasionally, however, and perhaps oftener
than the obscured surface indications now lead us to suspect, the
faults are broken up into series arranged en echelon. The Tabb fault
is a good example of the latter type.
When the displacement of the strata is sufficient to bring two litho-
logically distinct formations into juxtaposition, as, for instance, when
the sandstones of the Coal Measures or Chester are thrown down to
the level of the Princeton or St. Louis limestones, there is no diffi-
culty in tracing the fault; but where the displacement is insufficient
to produce this result very close stratigraphic comparisons are required
to establish its presence. Indeed, the difficulties proved almost insur-
mountable in the cases where the faults traversed the deeply weathered
areas occupied by the St. Louis limestone. In the cases where differ-
ent members of the Chester formation are on the two opposite sides
of the fault plane the difficulties are not so great, since the various
members of the Chester formation are usually distinguishable with-
out much trouble, and the line of the fault is very commonly marked
by protruding masses of quartzose sandstone.
Taken as a whole, the fractures fall into at least two (and probably
four) well-defined systems, one trending northeast, the other north-
west. The northeasterly system is the more prominent and its frac-
tures perhaps more generally mineralized than those of the other
systems. When platted on a map this system of faults, on the Ken-
tucky side of the river, presents an obscure fan-shaped arrangement,
radiating and diverging eastwardly from the region between Salem and
Pinckney ville, in Livingston County. The ribs of the fan pass through
Crittenden County, and its successive lines become more and more
easterly as we approach the southern boundary of that county and
enter Caldwell, where they strike from a little north of east to a few
degrees south. It is to be understood that the fan-shaped arrange-
ment of the main fractures of this system has no known genetic rela-
tion to the dikes of the district. No igneous rocks are known to occur
Bull. 213—0:3 14
210 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
within 6 miles of the imaginary converging point, while the trend of
all the dikes sufficiently known to permit a statement concerning their
directions is essentially at right angles to these fractures, being north-
west instead of northeast.
A well-defined northwest system of fractures, to which probably all
the known dikes of the district belong, finds its best expression in the
western half of Crittenden County. Here the trend of tin' dikes and
faults belonging to the system varies between N. 30° W. and N. 37° W.
The fractures of this system usually caused only a very limited dis-
placement, but they contain some of the largest mineral deposits of
the district, notably at the Eureka, Old Jim, and Holly mines.
The northeast faults found in the northern and eastern parts of
Livingston seem to indicate a distinct third system, extending across
the Ohio from Hardin and Pope counties, 111. Similarly, the north-
west fractures occurring in the northern parts of Crittenden and Liv-
ingston counties, having a direction varying but a few degrees either
way from N. 20° W\, probably belong to a fourth system, which, Like
the other, has its strongest development in the Illinois counties
mentioned.
The fractures, whether mineralized or not, frequently furnish chan-
nels for descending underground waters, as is evidenced by the cor-
rosion of the walls, forming in the case of some of the apparently
unmineralized fractures open fissures or crevices filled with nn] clay.
Sink holes are common along some of the fractures, and caverns are
known to follow them for short distances.
The formation of the mica-peridot ite dikes, of which seven or eight
are known in Crittenden County, and one in Pope County, 111., is
believed to have taken place prior to the extensive faulting of the
region. They were probably produced by an accumulation of molten
matter within this portion of the crust of the earth, causing its eleva-
tion and fracturing and subsequent intrusion of the igneous masses.
The strain on the continuity of the strata produced by 1 heir elevation
caused the relatively brittle limestone to part along certain lines and
form fissures. The more i>liable shales and sandstones of the Chester,
however, frequently accommodated themselves to the strain, so that
the intruded mass failed to pass through them, but spread itself hori-
zontally in sheets between the bedding planes. The fissures occupied
by the dikes are generally very nearly vertical and (pi ite straight in
their courses, and although narrow, varying from about 2 feet to
nearly 25 feet in width, some of them have been traced for miles.
THE VEINS AND VEIN MINERALS.
By W. S. Tangier Smith.
The well-defined veins of this district almost without exception fill
fissures due to faulting. They are found in the Princeton, St. Louis,
and Chester formations; mainly in the first two. Where two of the
formations have been faulted into juxtaposition, veins frequently
smith] LEAD, ZINC, AND FLUORSPAR OF WESTERN KENTUCKY. 2.11
occur along the fault or in a fissure not far from and parallel to the
fault. Veins have been occasionally noted in groups of two or more,
either parallel or arranged en echelon. Their width is variable; the
maximum thus far recorded — in the case of well-defined veins — is
nearly 15 feet. Most of the important veins, however, do not exceed
6 or 8 feet in width. The veins all dip at a high angle.
Most of the veins show distinct evidence of movement either in the
displacement of the beds on the opposite sides of the fissure or in
shearing with or without well-defined slickensiding. The shearing
occurs both in the vein itself — especially near the walls — and in the
country rock, where it may extend as much as 50 feet from the veins.
The walls of the veins are usually, though not always, well defined,
and are frequently marked by pronounced slickensiding. One or
both walls are often fractured where the vein is in limestone, and are
frequently much seamed with minute veins of calcite or fluorite.
This seaming also frequently accompanies ordinary fracturing of the
limestone where no vein has been formed. The shear planes are some-
times marked by thin, clayey partings, especially in the Chester sand-
stone. Also, where the veins are adjacent to this formation, dragged-in
shales along the walls are not uncommon. These sandstones, where
intersected by fissures, whether the latter are filled with vein matter
or not, or where they have been filled with igneous rock, have been
as a rule silicified, to a greater or less extent, to a hard quartzite.
This quartzite, being resistant to erosion, appears in dike-like forms
above the surrounding rocks, the shearing giving the effect of verti-
cal or highty inclined bedding.
The principal minerals of the district are galena and its oxidation
products; sphalerite ("blende") and its oxidation products, smithson-
ite (" carbonate"), and hydrozincite; pyrite (or marcasite), greenock-
ite, fluorite ("fluorspar"), barite, calcite ("calc spar"), quartz, and
ankerite. Nearly all of these occur either in the veins or in connec-
tion with them. In addition, bitumen is occasionally found in the
veins.
Fluorite. — Fluorite is by far the most important of the vein min-
erals, comixhsing, as a rule, the greater part of the vein, the remainder
being made up of a varying proportion of other minerals, with
dragged-in country rock. In some cases the vein is composed almost
wholly of fluorite ; in others the proportion of other substances is so
large as to make it unprofitable to work the deposit. The associated
minerals and rock fragments may be found throughout the vein, but
in general they are mo^t abundant toward the margins. The fluorite
veins frequently show a pronounced banding, due either to shearing
or to a variation in the grain of the fluorite in bands parallel to the
walls of the fissure.
In the Chester sandstone fracturing has frequentty resulted in
brecciation rather than in a well-defined fissure, and the breccia may
be more or less completely cemented with fluorite. Barite may occur
212 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
under similar conditions, and both are found replacing sandstone to
a greater or less extent.
The usual mode of occurrence of fluorite is massive and granular.
It is also found as cubic crystals in vugs or coating the walls of small
fractures in the country rock; but well-crystallized occurrences are
comparatively rare. It is generally translucent, though rarely trans-
parent; its color is usually white, sometimes purple, and occasionally
yellow.
Calcite and barite, — Of the minerals associated with the fluorite
calcite is the most abundant, It occurs as white crystals or coarsely
granular masses scattered through the veins. Barite is next in
amount, though it is not found in most of the veins. AVhere it occurs
with the fluorite it is apparently intergrown with it. There are also
in both the St. Louis and the Princeton limestones veins of fine-grained
barite occurring either alone or with a minor proportion of fluorite;
but so far, except in one instance, this mineral has not been found in
sufficient quantity to pay for mining.
Galena, — Galena occurs in many of the fluorite veins, sometimes in
quantities large enough to make it profitable as a by-product, though
in most cases it is insignificant in amount. It usually occurs in grains
and crystals of varying size, though generally small, disseminated in
the fluorite, for the most part near the Avails of the veins, and fre-
quently concentrated in lines parallel to the walls. Occasionally
it is met in elongated columnar forms, due to shearing in the veins.
Sphalerite. — Fragments of the wall rock, whether quartzite or lime-
stone, are common in most of the veins. They have in some cases
been replaced by fluorite to a greater or less extent. Sphalerite,
which is found in many of the veins, occurs mainly as minute grains
disseminated in the included fragments of limestone, frequently con-
centrated near the contact between the fragments and the inclosing
fluorite. It is also found occasionally disseminated in the fluorite
and in the wall rock where this is of limestone. This fine-grained
sphalerite is more abundant, on the whole, than the galena, and will
prove of economic importance if a satisfactory method of separating
it from the associated fluorite is found. Sphalerite is also found here
and there (especially in the region southwest of Crittenden Springs)
in coarser form and in greater amount.
There are a number of deposits in which sphalerite or its oxidation
products have been found apparently unassociated witli fluorite,
notably in the Old Jim mine, where the ore (smithsonite with some
hydrozincite) occurs adjacent to a dike of peridotite. Here as in other
similar instances, however, mining has not been carried deep enough
to show the character of the unoxidized ores.
Effects of oxidation. — Above ground-water level the oxidized and
carbonated surface waters have removed from the veins much or
most of the calcite which they contained, as well as the included
fragments of limestone, and have altered the country rock to a greater
Smith.] LEAD, ZINC, AND FLUORSPAR OF WESTERN KENTUCKY. 213
or less extent, but they have had comparatively little effect as yet on
the fluorite and barite. The galena has not been oxidized to any con-
siderable extent, and is still found near the surface. The fine-grained
sphalerite has been largely removed from the veins, having been in
part altered to smithsonite (zinc carbonate), which in turn is being
slowl}x dissolved and removed by the surface waters. At the Old Jim
mine the zinc salts in solution, reacting with limestone, have replaced
it here and there with zinc carbonate. The result of the leaching out
of the calcite and limestone fragments has been to leave the fluorite in
a more or less honeycombed condition. Where it was not originally
associated with these substances it is usually found in lumps. Wher-
ever the grains have been loosened or separated it is found in a sand}7
or gravelly form known as gravel spar. In all these cases it is usu-
ally associated with red clay formed as a residual product on the solu-
tion of the adjacent limestone.
The depth of oxidation along the course of the veins is variable and
may be as much as 100 feet or more. In a few cases fresh, unaltered
vein matter and country rock come nearly or quite to the surface.
Descending surface waters have occasionally formed channels along
a fissure, thus carrying oxidation and oxidized products considerably
below the normal level of underground water.
Vertical distribution of vein minerals. — As far as the deposits have
been developed it can not be proved that the fluorite, on the whole,
actually decreases with depth, though it is said to do so in some cases.
This assumed decrease may be merely comparative, since the associ-
ated calcite in many instances appears to increase with depth,
although it is quite probable that in general this is due merely to the
fact that it has been removed by surface waters at the higher levels.
Galena, in general, appears to be most abundant near the surface,
and on the whole to decrease with depth, though in many instances
it is not apparently more abundant at one level than at an another.
Above the level of underground water fine-grained sphalerite lias
been generally removed or changed to carbonate. Below this level it
seems probable, from what has been observed, that it does not materi-
ally increase in amount with depth. The coarser occurrences of the
sphalerite may be due to secondary enrichment, the finer-grained
mineral having been oxidized and carried downward in solution
below ground-water level, where it was redeposited in the coarser
form. Connected with these deposits there appears to have been
also some secondary concentration of the galena. No positive state-
ment can be made on this point, as none of the mines yielding coarse
sphalerite were accessible below ground-water level at the time the
region was visited by the writer; but if this is the true interpreta-
tion of the facts, these deposits of coarser sphalerite will be found to
be most abundant just below ground-water level, and will tend to
decrease with depth till only the finer-grained ore is found, the latter
representing the primary concentration.
ZINC AND MANGANESE DEPOSITS OF FRANKLIN FURNACE, N.J."
By J. E. Wolff.
According to a tradition, this celebrated occurrence of zinc and
manganese ore was noticed and prospected as early as 1640, but Lord
Sterling, after whom Sterling Hill is named, did the first mining in
1774. About this time several tons of the red zinc oxide were shipped
to London, yet the first description and analysis of this mineral were
given by Dr. Bruce in 1810, and of franklinite by Berthier in 1819.
The Mine Hill deposits were worked for iron ore about the beginning
of the last century, but there was not much mining for zinc until
after 1840. Different parts of the deposits have been worked more or
less continuously since then by different companies and there has
been long litigation, which has been finally settled by the consolida-
tion of all the interests. The ores are now treated at the mines by
magnetic separators, which separate the franklinite (as well as the
garnet and other impurities) from the willemite and zincite, while the
calcite is removed by jigging. The principal uses of the zinc ores are
for metallic zinc and zinc white, and of the manganese for Bessemer
steel.
The ores occur at Mine Hill (Franklin Furnace) and Sterling Hill
(Ogdensburg), localities 3 miles apart, and at no other place has
exploration found more than traces of the ores. The deposit is in the
white Franklin limestone, and at Mine Hill, where t lie surface and
underground workings are best developed, lies about 30 feet from the
gneiss boundary on the west, along the west limb.
The ores consist of zincite, the red oxide of zinc (ZnO), containing
94 per cent zinc oxide and 6 per cent manganese oxide; willemite,
silicate of zinc (Zn2Si04), containing 67 to 69 per cent zinc oxide
and 5 to 10 per cent manganese oxide; and franklinite (FeZnMn) O
(FeMn)203, containing 56 to 67 per cent ferric oxide, 4 to 10 per cent
manganese sesquioxide, 7 to 23 per cent zinc oxide, 10 to 16 per cent
manganese oxide. The ores are usually accompanied by varying pro-
portions of calcite. The contrast between the deep-red zincite, green
willemite, lustrous black franklinite, and white calcite is very strik-
ing. The proportions of these minerals vary constantly, so that
sometimes zincite is abundant, sometimes only present in traces, and
o From the descriptive text of the Franklin Furnace folio, Geologic Atlas of the United States-
in preparation.
214
wolff.] ZINC AND MANGANESE OF FRANKLIN FURNACE, N. J. 215
so with the relative proportions of the other three. The size and shape
of the" minerals also vary greatly. A common form is the "shot"
ore in which irregular rounded franklinite, willemite, and calcite
grains, with or without zincite, occur together without marked band-
ing; at other times the ore is finely banded or foliated, and these
minerals are then seen to be in small flattened lenses or elongated
pod- like masses parallel to the foliation; or such forms may be due
to an aggregate of several grains. At other times large round masses
of zincite, 1 or 2 inches in diameter, are scattered through coarse cal-
cite like a pudding stone, or franklinite occurs similarly in rough
octahedral crystals. These four minerals have evidently been formed
contemporaneously, for each is found inclosed in the others and
neither in general has any distinct external crystal planes, although
the franklinite has a tendency to occur in rounded octahedral grains.
These structures in general simulate so closely that of the associated
gneisses that they must be classed together.
GEOLOGIC OCCURRENCE.
At Mine Hill the zinc deposit is much like a bedded deposit, and
forms a band which outcrops on the surface as far north as the
extreme point of the gneiss band lying west of the white limestone,
and runs southwest for about 2,700 feet (Trotter and other mines),
when it makes a sharp curve and runs northeast about 600 feet (Buck-
wheat mine) as far as the trap dike, where it disapijears from the sur-
face, and has been worked underground in a northeast direction for
about 600 feet on a pitch of 27° to 32°. By diamond-drill exploration
the further underground continuation of this deposit to the northeast
was found at depths of 1,000 feet more or less from the surface, a
shaft was sunk, and extensive mining operations are carried on
(Parker shaft workings).
The west limb of the deposit is known as the " front vein" and the
east limb as the "back vein," while the connecting point is known as
the "South chamber."
Along the west outcrop the ore body has a width toward the north
end of 15 to 25 feet. It is separated from the gneiss by 30 feet of
limestone and dips east at from 55° to 60°. The distance from the
gneiss is remarkably constant, for the same 30 feet of limestone
between the foot wall of the ore deposit and the gneiss is found at the
surface, and 900 feet vertical^ below and 1,200 feet along the dip.
The foliations of ore and limestone are conformable.
At the Trotter mine the ore body is divided by a large mass of
granite, which was also found underground for a long distance. South
of this mine the deposit widens considerably. It has been followed
down about 500 feet along the dip from the outcrop of the west vein,
widening and narrowing and with some variation in the angle of dip.
216 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull.213.
At the Buckwheat mine the ore has been worked from the outcrop
down nearly 300 feet with the dip, which is very steep to the east, and
at the Parker shaft workings 1,000 feet from the surface
The comparison of the structure and extent of the workings along
the west vein and those of the Parker shaft shows an evident con-
tinuity of the deposit, dipping steadily downward to the east from
the outcrop for 1,300 feet, where it begins to rise again for 150 feet,
when the ore terminates. In the basin thus formed, and also in the
part forming the eastern edge, there is a great thickening of the ore.
At the Buckwheat mine the same structure is found, a crosscut driven
west to the west vein shows that the foot wall of the east vein curves
around to form the hanging wall of the west vein, the width of the
ore in the north slope of the Buckwheat mine is about double the nor-
mal width of the two veins (70 feet in the first, 35 or less in the sec-
ond), and the limestone forms an arch over the ore, the foliation of
which, and the structure of the franklinite bands in the limestone
roof, conforming to the arch of the ore, which pitches downward at
an angle of 27° to 32°. Putting all these facts together, the inter-
pretation on which all observers agree is that the east and west veins
are one continuous plane body of ore folded in a synclinal trough,
which narrows to the south and finally spoons out at the surface
in the south chamber workings; less positive is the theory that there
is a sharp subordinate anticline on the east side, with the two sides
compressed together and the axis pitching 27° or more to the north-
east. The fact is plain that there is a thickening of the ore and
that this thickened shoot pitches northeast at about the same angle
as the axis of the main synclinal trough or basin. The compass direc-
tion of this axis gradually curves to take a more northerly direction
in the Parker shaft workings so as to conform to the strike of the
west vein. The pitcli also flattens in the north workings to as low as
0°, and certain facts from the diamond-drill records show that the
structure is more complicated there, but the data available are too
fragmentary to permit a definite conclusion. It is noteworthy that
the pitch of 27° in the Buckwheat mine is also to be seen in the
gneisses lying just west, an argument for the contemporaneity in
present form of the gneiss, white limestone and ore deposit.
In several places in the underground workings at Mine Hill, granite
or syenite masses cut the ore. In 1898 several of these were studied
in the Parker shaft workings. They run, like the surface granite
outcrops, nearly parallel to the general trend of the foliation of the
vein and yet cut distinctly across it in places. The granite is line-
grained for several inches from the contact, the ore is hardened for
some distance, and between granite and ore there is a band of yellow
(Mn) garnet (polyadelphite) mixed with rhodonite, calcite, willemite,
franklinite, and a Mn. Zn. pyroxene ( jeffersonite?) ; the granite itself
also contains stringers and isolated masses of these minerals. Some-
wolfp] ZINC AND MANGANESE OF FRANKLIN FURNACE, N. J. 217
times a coarse vein-like aggregation of these minerals separates gran-
ite from ore A large number of the rare minerals come from these
underground granite contacts, and there can be no doubt that the
granite is later than the zinc bed and intrusive into it.
At Sterling Hill there is an analogous structure of east-west
limbs of the ore bod}7, outcropping on the surface in a hook and pitch-
ing under northeast at both ends, the west vein outcropping about
GOO feet from the turn, and the east vein about 1,500 feet.
The west vein has only been worked down a short distance from
the outcrop ; the east vein in places about 650 feet at an average angle
of 50° to 65°.
In the center of the canoe joining the two veins the axis pitches
50° NE. In the mines the pitch of the ore shoots is said to have been
generally 65°. At the apex of the trough the limestone is filled with
various silicates (diopside, jeffersonite, etc.), and was probably
impregnated with franklinite and zinc ores, now mined out. A little
farther north a large deposit of calamine was mined, which lay in a
bowl-shaped cavity on top of the limestone, and was undoubtedly
hydrated ore derived from the decomposition of the higher lying
portions of the zinc deposits.
ORIGIN OF THE ZINC DEPOSITS.
The descriptions of the structure and relations of these deposits
speak for their contemporaneity in present form and structure with
the inclosing white limestone and associated gneisses, and therefore
for a period of formation earlier than that of the intrusive granites,
although the difference in time may have been small. The ore
deposits are often not sharply defined from the limestone foot and
hanging walls, and the latter are shot through with franklinite, willem-
ite, etc. Horses of limestone or coarse calcite also occur in the mid-
dle of the ore deposit. It is believed that the zinc deposits acquired
their present structure and mineralogical composition contempora-
neously with the limestone, and that they represented originally a
local segregation of the zinc manganese and iron minerals in some
other form which may have been originally that of sulphides which
were then oxidized to carbonates, and the latter by metamorphism,
which caused the loss of carbonic acid with or without the substitu-
tion of silica, assumed the present form. Sphalerite (zinc sulphide)
has been found very rarely in the ore deposits and only in small
isolated masses, and the carbonates are equally rare, so that there is
little positive fact upon which to base a theory.
GEOLOGICAL SURVEY PUBLICATIONS ON LEAD AND ZINC.
Many papers relating to silver-lead deposits will be found included
in the list on pages 90 and 01 of this bulletin. The principal other
papers on lead and zinc, published by the United States Geological
Survey, are the following:
Bain, H. F., Van Hise, C. R., and Adams, G. I. Preliminary report on the
lead and zinc deposits of the Ozark region [Mo., Ark. J. In Twenty-second Ann.
Rep., Pt. II, pp. 28-22*. 1902.
Clerc, F. L. The mining and metallurgy of lead and zinc in the United States.
In Mineral Resources U. S. for 1882, pp. 358-386. 1888.
Hofmann, H. O. Recent improvements in desilverizing lead in the United
States. In Mineral Resources U. S. for 1883-84, pp. 402-47:5. 1885.
Iles, M. W. Lead slags. In Mineral Resources U. S. for 1883-84, pp. 440-
462. 1885.
Winslow, A. The disseminated lead ores of southeastern Missouri. Bulletin
No. 182. 81 pp. 1896.
•J is
IRON AND MANGANESE.
Reports on a number of the iron-ore fields of the country have been
issued by the United States Geological Survey within the last year,
and work in several important iron districts was carried on during
the field season of 1902. Summaries, both of the published reports
and of the unpublished results of the season's field work are presented
below. A paper on the utilization of slags, prepared for the last
volume of the report on Mineral Resources, United States, and sepa-
rately printed, but omitted by error from the bound volume, is here
republished. In addition to the papers included in the present sec-
tion, the ocher deposits of Cartersville, Ga., which are closely allied
to the iron deposits of the same region, will be found described on
pages 427 to 432 of this bulletin. On pages 214 to 217 will be found a
paper on the zinc-manganese-iron deposits of Franklin Furnace, New
Jersey, which may be of interest in the present connection. A list of
the principal previous publications by the Survey on iron and manga-
nese ores and mining districts will be found on page 256.
IRON ORES OF THE REDDING QUADRANGLE, CALIFORNIA.
Bv J. S. Diller.
Iron ore (magnetite) occurs in the Redding quadrangle at a number
of points on the contact between diabase and the Carboniferous lime-
stone. Numerous prospects have been opened on the contact about
Grey Rock, northeast of Bayha and on Pit River, as well as farther
northward, opposite the United States fishery. The openings gener-
ally show limonite, but it is derived from the decomposition of ore in
which magnetite and pyrrhotite play an important role, associated with
pyrite, chalcopyrite, light-green fibrous pyroxene, and garnet result-
ing from contact metamorphism. The prospects are generally made
in searching for copper ore, but at one place, about a mile south-
east of the United States fishery, on McCloud River, a much more
promising opening is operated, furnishing the iron flux at Bully Hill.
The ore is chiefly porous magnetite, which is often coated with irrides-
2V.)
220 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 2V6.
cent and stalactitic limonite, and opened to a width of 40 feet without
reaching the 1 imits. Small bands of garnet mixed with pyroxene occur,
and I races of copper ores have been reported. Lying essentially upon
the contact between the Carboniferous limestone and an igneous rock,
the ore is believed to owe its origin largely to this relation. Its
extent, however, is a matter of doubt, and the progress of the work
disclosing what is underneath is watched with much interest.
Similar bodies occur along the same limestone contact farther north,
upon the west side of the MeOloud, and should the mass referred to
above prove a large deposit it may lead to the development of an
important industry in that region.
T1L1ZAT10N OF IRON AND STEEL SLAGS.
By Edwin C. Eckel.
INTRODUCTION.
Iii recent years the attention of many technologists has been directed
to the problem, of slag utilization. Certain slags may, of course, be
considered as low-grade iron ores, and have been used as such for
many years. By far the greater portion of the slag annually j)ro-
duced by iron and steel works is not available for this use, however,
and it is only in comparatively recent years that uses have been found
for many of these slags. At present, slag is utilized extensively in
cement and slag-brick manufacture, as a fertilizer, and in the form of
mineral wool; to a less extent in the manufacture of alum, paint, and
glass; and a considerable quantity is disposed of less profitably for
use as road metal, railroad ballast, and in land reclamation. These
uses will be discussed in order.
SLAG CEMENT.
Slag cement, properly so called, is the product obtained by pulver-
izing, without calcination, a mixture of granulated basic blast-furnace
slag and slaked lime. This product, though in reality a member of
the class of pozzuolanic cements, is usually marketed as "Portland
cement," in spite of the fact that it differs from a true Portland
cement in method of manufacture, ultimate and rational composition,
and properties. Eight plants are at present engaged in the manu-
facture of this material in the United States, the production for 1901
being about 400,000 barrels, while that for 1902 was in the neighbor-
hood of 800,000 barrels. The writer has discussed the manufacture
of slag cement in detail in a recent publication." A brief resume of
the technology of the material in question is here given.
As to composition, the material used in the manufacture of slag
cement must be basic blast-furnace slag. Tetmajer stated that the
ratio should never be less than unity, and that the best results
2 Al O
were obtained when the ratio -^~~ gave a value of 0.45 to 0.50.
Si()2
Prost and Mahon later obtained good results from slags in which the
"Mineral Industry, Vol. X, pp. 84-95. See also Mineral Resources IT. S. 1SXX), p. 747, where a
description of two Alabama slag-cement plants is given.
221
222
CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
alumina was much higher than indicated by Tetmajer's ratio, and
analyses of slags used in practice are shown in the following table,
with the ratios 5^2 and * :j calculated for each slag:
kSi02 Si<J2
Analyses of slags in actual use.
Constituent.
Si02 .
A1203
FeO .
CaO _
MgO^
CaS__
CaS04
S __..
so3 _.
CaO
Si02
A1A
SiO,
Middles-
boro, Eng-
land.
31.50
18. 56
12. 22
3. IS
2.21
.45
:•}
L.34
59
Bilboa,
Spain.
32. 90
13.25
.46
47. 30
1.37
3.42
Choindez,
Switzer-
land.
26.24
24.74
.49
46. 83
.88
.59
.32
1.44
.41
1.78
. 93
Sanlnes.
France.
31.50
16.62
. 02
46. 10
1.40
Chicago,
111."
32. 20
15. 50
48. 14
2. 27
1.49
.48
Slags allowed to cool slowly are only feebly hydraulic, even if of
proper chemical composition. When used in the manufacture of slag
cement, therefore, the slag must be cooled as suddenly as possible.
This is effected by bringing the slag, as it issues from the furnace, in
contact with a jet or stream of cold water. This sudden cooling
"granulates" the slag, i. e., breaks it up into porous particles, and
has also two important chemical effects. One is that the slag, if of
suitable chemical composition, is rendered strongly hydraulic; the
other, that most of the sulphur is removed in the form of hydrogen
disulphide. After granulation the slag is dried, usually in rotary
driers, the Ruggles-Coles being a favorite American type.
The lime used for mixture with the slag should be low in magnesia,
well burned, and carefully slaked. At Chicago, where the Whiting
process is used, a small percentage of caustic soda is added to the
water used for slaking, the effect being to accelerate the set of the
cement. After slaking and drying, the lime is ready for mixture with
the granulated and dried slag, which usually has received a prelimi-
nary reduction in a crusher, ball mill, Kent mill, or other compara-
tively coarse reducer. The proportions used will vary from 20 to 40
parts of lime to 100 parts of slag. The mixture and final reduction is
usually accomplished, in the American plants, in tube mills. The
composition of a number of American and European slag cements is
shown in the following table of analyses collected from various sources:
ECKEi..] UTILIZATION OF IRON AND STEEL SLAGS.
Analyses showing composition of slag cements.
223
Constituent.
Choindez,
Switzer-
land.
Si02 _
ALO, -
FeO .....
CaO ....
MgO
S
SO,
Loss on ignition
19.5
17.5
54.0
Donjeux, Saulnes, rhic.ai,0 T11
France. France. cnicago, m.
24. 85
12.10
3.85
49.20
1.75
1.30
1.35
5.(55
22. 45
13.95
3.30
51.10
1.35
28. 95
11.40
0.54
50.29
2.96
1.37
Fnsley.
Ala.'
11.70
51.71
1.39
1.31
0.35
7. 50
3.39
The composition of good slag cements may vary within the follow-
ing limits: Silica, 22 to 30 percent; alumina and iron, 11 to 16 per
cent; lime, 49 to 52 per cent; magnesia less than L per cent; sulphur,
less than H per cent. It will be noted that the lime content is lower
and the alnmina-iron content higher than in a cement of the Portland
type. Slag cements also differ from Portland cement in being lower
in specific gravity and lighter in color. Normally, they are slower
setting than Portland cement, though this defect can be overcome by
treatment during manufacture. They are deficient in resistance to
mechanical wear, and do not set satisfactorily in dry situations. For
use underwater or in permanently damp ground, however, they would
seem to be of service.
PORTLAND CEMENT FROM SLAG.
True Portland cements, which must be sharply distinguished from
the slag (pozzuolanic) cements discussed in the preceding section of
this paper, can be made from mixtures of which one element is blast-
furnace slag. In this case the slag is ground, intimately mixed with
powdered limestone, and the mixture calcined and reground. Two
plants are engaged in the manufacture of Portland cement from slag
and limestone in the United States. An analysis of the "Universal"
brand of the Illinois Steel Company, a Portland cement made from
these materials, follows:
Analysis of Universal brand, manufactured by the Illinois Steel Company.
sicv_:
Per cent.
_. 23.62
A1A
CaO
MgO
so3_-
s. ....__
Loss on ignition
8.21
2.71
61.92
1.78
1.32
None.
0. 52
224
CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
Cecil von Schwarz, in a paper read before the Iron and Steel Insti-
tute of Great Britain, has recently described in detail German and
Belgian practice in the manufacture of Portland cement from blast-
furnace slag. The slag is granulated in order to remove sulphur and
to reduce the cost of crushing. The granulated slag is dried and mixed
with about an equal amount of limestone. To the mixture is added
about 3-J per cent of powdered slaked lime, and their intimate mixing
and reduction are accomplished in ball mills and tube mills. About
8 per cent of water is added, and the slurry is then made into bricks,
which are dried before charging into the kiln. A ring kiln is used,
with coke as fuel. The clinker is moistened, stored for six weeks,
and reduced in ball and tube mills.
Analyses of limestone, slag, and finished cement at << typical plant.
Constituent.
Limestone.
Slag.
Cement.
SiO,
1.6
1.0
30 -35
10 11
23. 70
A1203
6. 14
Fe203
1.80
FeO .
0.2- 1.2
3. - 4
MnO
CaC03
97.0
CaO . .
46 -49
0.5- 3.5
0.2- 0.6
59. 08
MgO
0.5
0.06
1.40
S03 _.
1.30
Loss on ignition . .
5.70
SLAG BLOCKS.
Slag, run into molds on issuing from the furnace, furnishes blocks
which have been used for paving, notably in Philadelphia. These
slag blocks are very durable, but objectionable because of their slip-
periness. This difficulty has been overcome, in English practice, by
casting the blocks in a double-sized mold, with a projection which
results in a notch passing around the slag block. The two halves of
the block are then split apart at this notch, and the rough fracture
surface of each is laid uppermost in paving.
SLAG BRICK.
The manufacture of slag brick can hardly be considered as being
more than a specialized phase of the manufacture of slag cement.
Slags, approximately of the same composition as those usee! in cement
making, are granulated, dried, and pulverized. Sufficient slaked lime
is added to bring the calcium oxide content of the mixture up to about
55 per cent, the mixing being carefully and thoroughly done. Dur-
ing or after mixing, a small amount of water is added, and the moist-
ened material is then fed to the brick machine. On issuing from this
the bricks are placed on racks to dry. The drying takes from six to
ten days, at the end of which time the bricks are ready for use.
ECKEL.]
UTILIZATION OF IRON AND STEEL SLAGS.
225
Slag bricks are light in color, varying from light to dark gray; they
weigh less than clay bricks of equal size, require less mortar in laying
up, and are equal to clay bricks in crushing strength. The following
analyses of slags used in slag-brick manufacture are fairly represent-
ative :
Analyses of slags used in slag-brick manufacture.
Constituent.
Si02.
A1203
FeO .
MnO.
CaO_
MgO.
S ___
1.
2.
3.
4.
22. 5
25. 8
27.0
33.0
14.0
17.3
19.3
18.67
3.3
1.5
1.7
1.0
.0
.0
0.1
4.25
51.0
51.4
51.5
40.0
1.4
0.4
2.5
2. 33
0.3
1.3
1.8
1.33
35.0
15.0
1.1
0.3
45.0
.0
0.4
FERTILIZERS.
The highly phosphatic slags produced by basic Bessemer converters
are valuable fertilizers, and are of great economic importance. In
Germany, especially, large quantities are annually sold under the
name of Thomas slag. In slags produced by this process the content
of phosphoric acid usually runs from 10 to about 25 per cent.
Analyses of basic Bessemer slags.
Constituent.
Si02
A1203 _
Fe203-.._
FeO ._..
MnO
CaO
MgO
K20, Na20
CaS
S
S03
PA-- -
H20,etc_-_
7.38
2.57
8.54
13.62
3.79
41.58
6.14
54
14.36
1.29
4.1
9.3
4
49.6
4.7
. 0
2
17.5
5. 8
1.5
15. 42
2.1
3. 5
45.04
6.42
4.
.32
18.1
5. 76
1.43
2.07
12.72
3.43
47. 34
6.01
5.10
4.01
2.49
12
5. 56
45.26
5.90
.80
8.19
1.23
61.02
91
19. 19
1.19
21.81
27.35
1. Redgrave, Jour. Soc. Arts, Vol. XXXVIII, p. 230.
2. German. Phillips, Trans. Am. Inst. Min Eng., Vol. XVII, p. 86.
3. English. Phillips, ibid., p. 86.
4. Redgrave. Jour. Soc. Arts, Vol. XXXVIII, p. 230.
5. Pottstown Iron Company , Pennsylvania. Morris, Trans. Am. Inst. Min. Eng. , Vol. XXI, p. 232.
6. Bohemian. Phillips, Trans. Am. Inst. Min. Eng., Vol. XVII, p. 87.
Bull. 213—03-
•15
226 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 11)02. [bull. 213.
The possible commercial value for agricultural uses of these high
phosphorus slags produced by the Thomas- Gilchrist process was early
recognized. At first, however, it was argued that in an untreated con-
dition they would be useless as fertilizers; that the phosphoric acid
they contained was not directly available for plants, and that the fer-
rous oxide would probably prove positively injurious to vegetable life.
Attempts were accordingly made to dissolve out the phosphates of the
slag and reprecipitate them. Fortunately this treatment was soon
shown to be unnecessary, for field experiments with finely ground but
otherwise untreated slags proved that they were excellent fertilizers.
From this date (1882) onward the use of Thomas slag as a fertilizer
has increased steadily, and it is now an important article of commerce.
Regarding the chemical composition of these slags, facts of great
economic importance were brought out by the work of Ililgenstock
and later investigators, and the efficiency of Thomas slags as fertiliz-
ing agents is now explained. In rock phosphates the phosphoric acid
exists combined with lime as the tribasic lime phosphate (3Ca()3P205).
In the slags above mentioned, however, the combination existing is
the tetrabasic lime phosphate (4Ca03P205). These two compounds
differ greatty in the degree of their solubility in saline solutions, the
tetrabasic phosphate being much more soluble than the tribasic. For
this reason the phosphate slags are more efficient as fertilizers than
the mineral phosphate. Jerisch states that about U percent of the
total phosphorus of slags is present in the form of phosphide of iron,
which is changed into phosphate in lie soil.
Many types of crushers and mills have been experimented with in
the pulverizing of Thomas slag. The ball mill, however, seems to be
the only one capable of economically crushing this product to the
fineness required — 75 per cent through a 100-mesh sieve.
The slight development of the basic Bessemer steel industry in the
United States necessarily renders the use of these phosphatic slags of
less commercial importance than in Europe. During the year 11)01
about 1,000 tons of phosphate slag, produced in the United States,
were sold as fertilizer. This American material has been tested b}r
the Maryland Agricultural Experiment Station, the report a of the
results being that slag phosphate gave a greater total yield than did
any of the other insoluble phosphates. The yield of corn with slag-
phosphate was not quite so much as with bone meal, but the yield of
wheat and of grass was greater. All yields were produced at less cost
with slag phosphates than with bone meal. The slag used in these
experiments was a commercial sample and contained 16.32 per cent
total phosphoric acid. Other commercial analyses of this fertilizer
show phosphoric acid contents of 21.03 and 22.24 percent. A com-
plete analysis of the slag from the Pottstown, Pa., converters is given
in the preceding table of analyses.
a Bull. Maryland Agric. Exp. Sta. No. 68, p. 28.
eckel.] UTILIZATION OF IRON AND STEEL SLAGS. 227
The slags produced in steel plants using the open-hearth process are
less valuable as fertilizers than those produced by basic converters,
as the former contain less phosphoric acid and more silica and lime
than do the basic Bessemer slags. A two-stage modification of the
open-hearth process — the Bertrand-Thiel process — gives slags higher in
phosphoric acid than ordinary open-hearth slags. It is even claimed
by Thiel a that the Bertrand-Thiel process produces a greater value
of slag, if both quantity and phosphoric content be considered, per
ton of finished steel than does the Thomas-Gilchrist process.
The slags resulting from processes other than those above noted are
not sufficiently phosphatic for use as high-grade fertilizers. Elbers
has, however, called attention5 to the fact that highly calcareous
blast-furnace slags might be profitably used as fertilizers in place of
the other forms of lime (marl, shells, etc.) now used by farmers.
MINERAL WOOL.
Over half of the material marketed as "mineral wool" or "silicate
cotton" is derived from slag, the remainder being manufactured from
natural rocks of different types.
Originally the process was carried out at the furnaces. At present,
however, the slag is bought from the furnace companies and remelted
in a small cupola. From this the molten slag issues in a small stream,
into which is injected steam or air under pressure. The effect is to
scatter the slag, small spherules of slag being blown out from the
main stream, each spherule carrying behind it a thread of slag.
The fluidity and composition of the slag and the pressure of air or
steam are manipulated so as to give the greatest proportion of fiber to
spherules, as the spherules are commercially unavailable and must be
separated from the fiber if present in much quantity.
No analyses of slags used in the manufacture of slag avooI are at
present available. A mineral wool made from natural rock gave on
analysis the following result:
Analysis of mineral wool made from natural rock.
Silica 37. 5
Alumina and iron oxide 20
Lime '.. 30.6
Magnesia 11.8
The presence of sulphur is a defect in most mineral wools made
from slag, as they must be carefully protected against moisture to
prevent the oxidation of the sulphur and the consequent destruction
of the pipes or other metallic surfaces on which the wool has been
used.
The most important property of slag wool, from a commercial point
of view,. is that it is a very poor conductor of heat. This property
a Chem. Zeit., 1901, p. 371. &Eng. and Min. Jour., November 3, 1900.
228 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
renders it available for all uses for which a nonconductor is desirable,
as steam-pipe coverings, safe linings, etc. In 1884, Mr. J.J. Coleman
carried out a series of experiments on the heat-conducting power of
various covering materials. His results" were as follows, the con-
ducting power of slag wool being taken as unity:
Comparative heat-conducting power of materials.
Slag wool . ---- 1.00
Hairfelt , 1.17 '
Cottonwool . 1.22
Sheep's wool 1.36
Infusorial earth . ^ 1. 36
Charcoal 1 . 40
Sawdust 1 . 63
Gas-works breeze 2. 30
Subseqently more elaborate experiments were made by Professor
Ordway, 32 materials being tested under conditions closely approxi-
mating to those encountered in actual practice. The following
results6 have been selected by the writer from Ordway's list and
rearranged and recalculated to permit the heat-conducting power of
slag wool to be taken as unit}*:
Comparative heat-conducting power of materials.
Loose wool 0.62
Loose lampblack .75
Hair felt .70
Compressed lampblack . . .82
Loose calcined magnesia .95
Slag wo< >1 1 . 00
Light carbonate of magnesia 1 . 05
Compressed carbonate of magnesia 1. 18
Ground chalk 1 . 58
Asbestos paper „ 1 . 07
Compressed calcined magnesia • 3. 28
Fine asbestos 3. 78
Sand 4.77
It will be noted that though Orel way's results are not so favorable
to slag wool as were Coleman's, both experimenters established the
fact that this material is the best of the noninfiammable coverings
tested.
PAINT STOCK.
In 1891 Mr. A. Sahlin described6 a plant then in operation at Boon-
ton, N. J., at which slag was utilized in the manufacture of paint
stock. The slags used were puddle slags and reheating cinder,
which, of course, can not be utilized in the manufacture of cements,
a Engineering, September 5, 1384, p. 237.
b Trans. Am. Soc. Meeh. Eng., Vol. V, p. 73.
o Trans. Am, Inst. Min. Eng., 1891.
ECKEI,.]
UTILIZATION OF IRON AND STEEL SLAGS.
229
fertilizers, alum, etc. Analyses of samples of these materials showed
the following1 compositions:
Analyses of puddle slag and reheating cinder.
Constituent.
Puddle
slag.
Reheating
cinder.
FeO
52.43
19. 62
6.41
.81
. 38
16.39
3.S4
71.29
Fe2Os ..
MnO
.21
CaO___.
ALA
7.78
Si02_._
20. 06
P,Or
27
S
Trace.
The slag was crushed in a Blake crusher to pass a three-fourths inch
screen, and finally reduced in a Cyclone pulverizer to pass 225 mesh.
The finest dust was used directly as paint stock. The coarser mate-
rial, after treatment with sulphuric acid, was calcined and reground.
This industry has been discontinued at Boonton, and it is believed
that no slag is at present used for that purpose in the United States.
ALUM.
The preparation of alum from highly aluminous slags is accom-
plished by means of the Lurmann process. So far the manufacture
of alum by this process has not been attempted in the United States,
though it has been carried out on a commercial scale in Europe. At
Donjeux, France, the process has been employed in connection with
the manufacture of slag cement, the gelatinous silica resulting from
the alum-extraction process being used to accelerate the set of the
cement.
The Lurmann process, in brief, is as follows: Slags, as high in
alumina as possible, are decomposed by means of hydrochloric acid.
The resulting solution of aluminum chloride is treated with lime car-
bonate, which serves to precipitate the alumina and any dissolved
silica that may be present. In treatment with sulphuric acid the
alumina is dissolved, leaving the silica. It is stated a that 100 kilo-
grams of slag, containing 25 per cent of alumina, will yield 180 kilo-
grams of alum and 31 kilograms of gelatinous silica. The silica is
used in the manufacture of soluble glass and, as above noted, in the
manufacture of slag cement. The process may even be profitably
arrested after the first stage, as the aluminum chloride then obtained
is marketable for use in certain sewage purification processes.
« Wagner, Chemical Technology, p. 439.
230 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
GLASS.
Small quantities of slag have been used in Europe in the manufac-
ture of the inferior grades of glass, but this use has never attained
much commercial importance. In America slag has never, to the
knowledge of the writer, been so utilized.
ROAD METAL.
In addition to its use as a paving material in the form of slag bricks,
discussed in preceding sections of this paper, slag has been somewhat
extensively used in highway construction as macadam.
Sections of roads constructed in New Jersey with slag macadam,
under State supervision, have proved entirely satisfactory. Near
Buffalo, N. Y., slag has been used to some extent in highway con-
struction, and to a greater extent in Pennsylvania and Alabama.
The most extensive use of slag for this purpose is, however, probably
in Maryland, where it has been utilized in highway construction in
the counties of Baltimore, Howard, and Prince George.
Prof. W. B. Clark refers to the use of slag for this purpose in
Maryland in the following words:''
Furnace slag has been found to be, under certain conditions, a highly satisfac-
tory road metal. It is not as valuable as the trap rocks, although its cementing
properties are excellent, except in the case of some of the materials from the old
furnaces. These old slags break down quickly and are readily ground into fine
dust, and for these reasons are of little value in road construction.
The slag from the present iron furnaces, on account of the large amount of lime
contained in it, is very valuable as a highway material. It compacts easily when
rolled and forms an even, smooth surface, while the fine particles unite as a hard
cement that grows firmer with time. The iron furnaces at Sparrow Point afford
material of this character that has already been demonstrated to be a valuable
road metal.
RAILROAD BALLAST.
In several States, notably in Alabama, slag is Largely used as rail-
road ballast. At the third annual convention of the American Rail-
way Engineering and Maintenance-of-Way Association, a committee
reported on this as follows:
Blast-furnace slag containing a small excess of lime and being of a glassy nature
will, when broken up under the track, fulfill the requirements of ballast to a very
large degree, If a large excess of free lime be present the slag soon becomes too
soft to hold the load, becomes concreted under the ties, and churns in wet weather.
Slag-ballasted track usually requires a lift of 2 or 3 inches, and to be surfaced out
of face at intervals of from two to six years, depending on the hardness of the
slag and the amount of traffic. Slag composed almost exclusively of hard, glassy
pieces approaches closely to the quality of rock ballast; on the other hand, slag
with a large amount of free lime is inferior to reasonably good gravel.
It will be noted that the noncalcareous, glass}7 slags, which are thus
said to be preferable for railroad ballast, are precisely the kinds that
"Maryland Geological Survey, Vol. Ill, 1899, p. 10.").
Eckel.] UTILIZATION OF IRON AND STEEL SLAGS. 231
are unsuitable for use as macadam for highway construction. It is
therefore evident that almost any type of slag will be of service for
one of these two uses.
LAND RECLAMATION.
In the vicinity of furnaces slag is of considerable local importance
as a cheap and readily transportable material for filling purposes.
Large quantities are annually used for land reclamation, filling of
abandoned mine workings, etc. The greater part of the slag so used
is, however, given away by the furnaces, and such uses may, there-
fore, be regarded rather as a means of inexpensively disposing of a
troublesome waste product than as a utilization of slag. Such meth-
ods of disposal are, of course, economical only when the slags are
unfit for the more profitable utilizations discussed in the preceding
seel ions of this paper.
MANGANESE ORES OF THE CARTERSVILLE DISTRICT, GEORGIA."
By C. W. Hayes.
Closely associated with the Georgia deposits of iron ore (see pages
233-242) are extensive deposits of manganese. These have been
quite fully described b}' Dr. Penrose,6 and require only brief mention
here. All the iron ore contains traces of manganese, but the main
deposits of the latter ore are quite distinct from the iron. The ore
occurs, like the brown hematite, embedded in a heavy mantle of
residual clay, associated with chert and angular fragments of quartz-
ite. The proportion of clay to ore is usually larger than in the
deposits of brown hematite. The ore occurs as small concretions
scattered through the clay, and also in the form of veins, penetrating
the clay in an irregular manner. It has the appearance of having
been deposited by solutions percolating through the residual mantle.
The original source of the manganese was probably the Beaver lime-
stone, although some of it may have come from the Weisner quartz-
ite. The deposits occur with about equal frequency in the residual
material derived from the two formations.
Dr. Penrose holds the view that some at least of these deposits
existed in their present form in the rocks of the region before weather-
ing, and are therefore strictly residual. While this may be true in a
few cases, the writer has found no evidence of it in the field; and the
manganese ores are regarded, like the iron ores with which the}7 are
associated, as purely secondary deposits, their distribution being
determined chiefly by chemical and physical conditions, rather than
by the outcrop of beds especially rich in manganese.
Although, in the aggregate, a large amount of ore has been mined
from this district, most of the work has been done in a primitive and
inefficient manner. It is probable that with modern appliances a
large amount of material would pay for working which does not con-
tain a sufficiently large proportion of ore to be profitably worked by
the present methods.
"Abstracted from the descriptive text of the Gartersville folio of the Geologic Atlas of the
United States, in preparation.
b Penrose. R A. F., jr., Manganese, its uses, ores, and deposits: Ann. Rept. Geol. Survey
Arkansas, Vol. I, 1890, pp. 418-426.
232
IRON ORES OF THE CARTERSVILLE DISTRICT, GEORGIA.
By C. W. Hayes and E. C. Eckel.
One of the most productive iron-ore districts in the Southern
Appalachians lies in the vicinity of Cartersville, Bartow County, Ga.
The ore deposits of this region are so directly related to the stratigra-
phy and structure of the area that a brief description of the geologic
features must be given before taking up the subject of the origin and
position of the ore deposits.
GENERAL GEOLOGY.
Stratigraphy. — The area in question occupies the southeastern half
of Bartow County, Ga. Its surface is about equally divided between
the older crystalline and metamorphic rocks which occupy the Pied-
mont Plateau and Appalachian Mountains in the east, and the unal-
tered Paleozoic formations which occupy the Appalachian Valley on
the west. The line of separation between these two groups of forma-
tions in the Cartersville district is located as follows: Beginning at the
north, it lies about half a mile east of Fairmount post-office, and
runs almost due south for about 7 miles, when it swings eastward to
near Martins Mill. From this point it takes a southwest direction,
passing half a mile west of Rowland Springs, and then turns south-
east, crossing the Etowah near the old iron works and crossing the
railroad about a mile southeast of Emerson. From the point at
which it crosses the railroad the line pursues an almost southerly
direction for a few miles; then turns northwest, almost reaching the
Etowah at the Free Bridge, 4 miles from Cartersville, and finally
turns southwest, passing about 2 miles south of Stilesboro and Tay-
lors ville.
As noted later, this line between the two groups of formations
marks, throughout most of its extent, the position of the Cartersville
fault, which is the most important structural feature of the region.
The formations of the valley belt, to the west or the Cartersville
fault, are, in ascending order, the Weisner quartzite, the Beaver
limestone, the Rome and Conasauga shales, and the Knox dolomite.
All, except the latter, belong to the Middle and Lower Cambrian; and
the lower portion of the Knox dolomite should probably also be classed
with the Cambrian. The principal outcrop of the Weisner quartzite
2:}:]
234 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
forms a nearly continuous band, 15 miles in length, and generally
from 1 to 3 miles in width, which occupies the central portion of the
area. The formation is in contact on the east with the Cartersville
fault; its base is nowhere shown. It consists chiefly of fine-grained
vitreous quartzite, although it also contains some beds of fine con-
glomerate and, probably, considerable beds of siliceous shales. The
latter, however, are usually concealed by the abundant debris from
the quartzite beds, which tend to break up into angular fragments
when exposed to atmospheric conditions. Two subordinate outcrops
of the quartzite occur near the western margin of the area, being-
brought to the surface by small faults. The thickness of the forma-
tion is probably 2,000 or 3,000 feet, and ma}^ be considerably more;
but it can not be accurately determined because of the intense fold-
ing which its beds have undergone, and the absence of satisfactory
exposures.
West of the quartzite is a narrow belt of deep, red soil, usually
forming a level valley. This is underlain by the Beaver limestone,
a formation which rarely appears at the surface, its outcrops being
almost every where covered with a deep mantle of red clay, in which
occasional masses of vesicular chert are embedded, along with much
angular quartzite derived from the adjacent quartzite ridges. The
few natural exposures of this formation which have been observed,
together with the results of drilling, indicate that it is a gray crystal-
line dolomitic limestone, becoming shaly in places, and containing
occasional masses of chert. It is much more readily soluble than the
purer blue limestone; and its impurities form an abundant residual
mantle. In addition to the main belt which it forms along the west-
ern base of the quartzite ridges, it underlies a broad level valley near
the western margin of the district extending southward from Grass-
dale to the line of the Atlantic and Western Railroad. The thickness
of the Beaver limestone has not been accurately determined; but it
is probably between 800 and 1,200 feet. With these two formations,
the Weisner quartzite and the Beaver limestone, a majority of the ore
deposits in this region are associated.
Overlying the Beaver limestone is a very great thickness of shales,
constituting the Rome and Conasauga formations; and above the
shales is the Knox dolomite. The latter is a massive formation from
3,000 to 5,000 feet in thickness, composed of gray crystalline dolomite,
with an abundance of chert. In adjacent regions it is intimately
associated with extensive deposits of iron-ore; but it is unimportant
in the present connection.
The rocks on the opposite side of the Cartersville fault, occupying
the eastern half of the district, present considerable variety in com-
position and age. A large area, extending from Stamp Creek south-
ward across the Etowah River, to the Atlantic and Western Railroad,
is occupied by the Corbin granite, which is, for the most part, a mas-
hayes and egkel.] IRON ORES OF CARTERSVILLE DISTRICT, GA. 235
sive coarse-grained rock, containing large porphyritic crystals of feld-
spar (microcline), in a groundmass of plagioclase feldspar, muscovite
mica, and bine quartz. Some portions of the rock have undergone
considerable alteration, by which it has been converted into an augen-
gneiss. This area of Corbin granite at one time probably formed an
island, since it is surrounded, in part at least, by rocks derived from
its waste. These are feldspathic conglomerates in which the blue
quartz and the porphyritic crystals of microcline, which characterize
the granite, can be readily distinguished. In some places the transi-
tion from granite to conglomerate is so gradual that it is difficult to
determine the exact boundary between the two formations. The
development of the gneissoid structure in the granite evidently took
place after it was deeply buried by sediment, for the alteration of the
latter is even more marked than that of the granite itself. Wher-
ever the granite is not bordered by coarse conglomerate or quartzite
it is in contact with black graphitic slates, which generally overlie the
coarser sediments.
These conglomerates and slates associated with the granite belong
to the Ocoee series, which reaches its greatest development in eastern
Tennessee and western North Carolina. No fossils have yet been
found in the rocks of this series, although man}7 of them are only
slightly altered. They contain limestones and slates similar to por-
tions of the adjacent valley formations, but the latter are always found
to contain more or less abundant traces of life. In the absence of
fossil evidence their age can not be definitely determined, but on
structural evidence, obtained chiefly in Tennessee, they are believed
to be Lower Cambrian with possibly some pre-Cambrian.
The rocks of the Ocoee series generally show an increasing degree
of metamorphism toward the southeast; and within a few miles of
this region they pass into schists and gneisses, the original form of
which, whether igneous or sedimentary, can not be readily deter-
mined. This increased metamorphism toward the southeast is due in
part to the greater compression which that region has suffered, and
in part to the presence of considerable bodies of various igneous rocks
which have been intruded into the sedimentary beds. These intrusive
rocks present considerable variety in composition, varying from
extremely basic diabase to acid granites. The most common variety
is a diorite, which was among the earlier intrusions, and has been
snbsequently converted for the most part into amphibolite-schist.
Two belts of this basic schist pass across t lie southeastern corner of
the district. Its southeastern corner is occupied by the Acworth
gneiss, which, like the Corbin granite, is probably Archean in age,
and formed the foundation on which the oldest sediments of the region
were deposited.
Structure. — In common with other portions of the southern Appa-
lachian region, the Cartersville district has been subjected to intense
236 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
compression in a northwest-southeast direction. From evidence
obtained in adjoining regions, it appears probable that this compres-
sion, and the subsequent folding, began in early Paleozoic time, and
continued at intervals up to its culmination at the close of the Car-
boniferous. It resulted in the formation of folds and faults in the
valley rocks and in the development of a slaty cleavage or schistose
structure in the older rocks to the east, while the latter were thrust
upward and westward relatively to the former, producing the great
Cartersville fault. The region west of the Cartersville district is
occupied b}T a broad, gentle syncline of Knox dolomite. This mas-
sive formation appears to have resisted folding, and to have trans-
mitted the thrust in such a manner that while its own beds retained
very nearly their original horizontal position, the beds coming to the
surface in narrow belts on either side were intensely folded. Thus
the shales which occupy the western portion of the district are highly
contorted, and* are doubtless intersected by numerous small faults.
Also, considerable slaty cleavage has been developed in them. The
Weisner quartzite likewise resisted folding to some extent, although
its beds were thrown into the form of an anticline with numerous
irregular minor folds. The irregularity of the anticline is shown by
the character of its contact with the overlying limestones to the west.
In addition to the folding which the quartzite has undergone, it is
doubtless intersected by numerous faults, the evidence of which is
seen in its crushed and brecciated condition at many points. Owing
to the character of the outcrops, however, these faults generally can
not be located or traced.
The folding referred to brought about certain mechanical and
chemical conditions favorable for the deposition of mineral deposits,
and hence has an important bearing on the economic geology of the
district. It is frequently observed that the originally compact vitre-
ous quartzite is converted into a rock somewhat resembling jasper.
Chert from the overling limestone, under similar conditions, is
altered in the same manner; and it is often impossible to distinguish
between the final products of the alteration of rocks originally wholly
unlike. Portions of the quartzite have been converted into a spongy
rock, containing innumerable fine cavities lined with small quartz
crystals and stained with yellow ocher. This form of alteration is
probably due to the circulation through the rock of thermal waters,
by which the quartz was taken into solution and in part redeposited,
along with more or less iron oxide.
The line marking the Cartersville fault departs in this region from
its rather regular course across northwestern Georgia, making a dis-
tinct embayment to the east in passing around the belt of Lower
Cambrian quartzite and limestone. On either side of this region the
fault brings the soft slates of the Ocoee series in contact with Cam-
brian shales of a similar character. The actual plane of contact
hayes and eckel.] IRON ORES OF CARTERSVILLE DISTRICT, GA. 237
between the formations on opposite sides has been observed at many
points. The older rocks above always have a well-developed slaty or
schistose structure, and are but little more altered immediately at the
fault than elsewhere. The underlying rocks, on the other hand,, are
much more intensely folded and brecciated immediately at the fault
than a few feet distant. The fault plane itself is usually marked
by a bed of breccia, a few inches or feet in thickness, and made
up of the comminuted fragments of the formations on either side.
This fault inane dips to the east, usually at angles varying between
5° and 20°, and is parallel, in a general way, with the cleavage and
bedding of the rocks on either side.
The Weisner quartzite varies greatly in thickness within a short
distance. It has the appearance of a delta formation rather than an
evenly distributed littoral or marine deposit. North and south of its
present outcrops in this region it probably becomes very much thin-
ner, and its local thickening has doubtless influenced the structure in
this region. Another factor which has been important in producing
this peculiar structure is the presence of the great mass of granite to
the east of the fault. This is the only point at which massive rocks
of this character approach so near the fault line. They are usually
separated from the western margin of the metamorphic rocks by a
belt, several miles in width, of readily yielding slates and schists. It
is evident that the conditions for the formation of a thrust fault of
great lateral extent are much more favorable in bedded sedimentary
rocks than in the massive igneous rocks, such as the Corbin granite
The latter appears to have acted like an immovable buttress against
which the rocks from the west were thrust. It will readily be under-
stood that, on account of these massive quartzites on the west and the
still more massive igneous rocks on the east, this portion of the Car-
tersville fault differs materially from that to the north and south; and
further, the reasons will be seen for the very considerable alteration,
both physical and chemical, in the valley rocks adjacent to the fault.
IRON ORES.
The iron ores of the southern Appalachian region fall naturally into
five distinct groups, as follows: (1) Magnetite, (2) specular hematite,
(3) red hematite or fossil ore, (4) carbonate or black-band ore, and
(5) brown hematite or limonite. Only two of these groups occur in
the Cartersville district, namely, the specular nematite and the brown
hematite or limonite, and of these, the latter is much the more
important.
Specular hematite. — This variety of ore occurs at two points in the
district in sufficient abundance to be mined with profit. One is
about 2 miles southeast of Warford and the other between Emerson
and the Etowah River. The ore occurs at both localities as a band
in the quartzite, and both the ore and the inclosing qua tzite have a
238 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
strongly developed schistose structure. The ore passes into the
quartzite by a gradual transition, and only the richest parts of the
bed can be worked. The greater part of it is quite siliceous. Even
the purer portions of the ore contain many inclusions of white sac-
charoidal quartz, generally drawn out into long, slender filaments. In
some cases the iron appears as flattened oolitic grains embedded in a,
ground mass of white quartzite. It is evident that in these deposits
the iron existed in the quartzite before the alteration of the latter.
It may have been in the form of the carbonate or of the hydrous
oxide, and possibly, in £>art at least, of the sulphide. Some portions
of the ore contain what may possibly be greatly altered pseudomorphs
after pyrite. The ore is not appreciably magnetic; is nearly black in
color and has a bright metallic luster. It is called "gray ore" by the
miners, to distinguish it from the brown hematites of the district.
The specular hematite outcrops at short intervals, along a line
lying a short distance east of the Western and Atlantic Railroad, from
a point about 1 mile north of Emerson station to the north side of the
Etowah River. It is possible that this belt extends still farther north,
so as to include the workings noted near Warford, but outcrops
have not been noted in the intervening space. South of the Etowah
River the specular hematite has been worked to some extent, by
means of pits, open cuts, and a short tunnel, on the properties of the
Roan and Etowah Iron companies. The ore from these properties
ranges from 55 to G5 per cent in metallic iron, and at several of the
pits it falls within the Bessemer limit for phosphorus. The ore
bodies, however, do not appear to be sufficient in size to justify
exploitation on a large scale. In many of the pits the silica content
is high, and no cheap and simple concentrating system is available
for separating the purer ores from the more siliceous portions.
Broivn hematiti or limonite. — Several varieties of this ore occur in
the southern Appalachians, and are more or less distinct in their
appearance, manner of occurrence, and mode of formation. The
most important of these are (1) gossan ores, (2) Tertiary gravel ores,
(3) concentration deposits, and (4-) fault deposits. Only the two
latter varieties occur in the Cartersville district; but all four of
the classes occur in the immediate vicinity, and may be briefly
characterized.
1. The best-known deposits of gossan ore occur in the Ducktown
district. As is well known, copper occurs there associated with great
quantities of pyrrhotite. The latter has been oxidized at the surface
to limonite, and during the process of oxidation the copper has been
concentrated at the bottom of the weathered zone, forming the rich
deposit of "black copper" overlying the unaltered pyrrhotite. The
gossan ore has a variable depth, down to 50 feet or more, and con-
sists of soft, porous, ocher-yellow limonite.
2. During Tertiary time the valley region was reduced very nearly
hayes and kckel.; IRON ORES OF CARTERSVILLE DISTRICT, GA. 239
to sea level, and in its lower portions, chiefly those underlain by the
Chiokamauga limestone (the next formation above the Knox dolo-
mite), swamps were formed which received drainage from the
adjacent regions, and in which extensive deposits of bog ore were
formed. When the region was elevated, the limestone areas were
again reduced more rapidly than the adjacent areas underlain by
dolomite, and doubtless much of the accumulated iron ore was
removed by erosion. Around the margins, however, the ore remained
embedded in the residual clay. Deposits of this character are
especially abundant in the Rockmart and Cedartown districts, south-
west of the Cartersville area. These districts comprise a number
of areas of Chickamauga limestone, surrounded by zones which
contain large quantities of iron ore. This is usually in the form
of gravel ore, composed of concretions from the size of shot up
to a foot or more in diameter, embedded in the residual red clay,
and associated with more or less chert from the underlying Knox
dolomite.
3. The brown hematites of the third class, here called concentration
deposits, constitute the most important deposits of the Cartersville
district. They may occur wherever a limestone is underlain by an
insoluble and impervious stratum, such as sandstone or quartzite.
Favorable conditions for this accumulation occur in northwest Geor-
gia and Alabama, at the contact of the Lower Carboniferous lime-
stone with the sandstones which sometimes underlie it, and at the
contact of the Beaver limestone with the underlying Weisner quartz-
ite. The Beaver limestone is more readily soluble than the forma-
tions on either side, and hence, in the erosion of the region, it has
always formed valleys. At various times these valleys have received
the drainage, not only from the adjacent quartzite and limestone, but
probably also from other of the valley formations, and the widely dis-
seminated iron leached from these formations during the process of
decay has been transported to the limestone valley and there concen-
trated upon the underlying impervious quartzite. As the surface of
the limestone was lowered, chiefly by solution, upon successive eleva-
tions of the region, remnants of the ore deposits thus formed were left
resting upon the underlying quartzite and marking elevations at which
the surface of the limestone had remained for considerable periods.
These deposits are composed in part of gravel ore and in part of
masses of considerable size, in some cases reaching many feet in diam-
eter. Where the large masses of ore preponderate, it is probable that
they represent replacements of the limestone by iron-bearing solutions
rather than ordinary bog-ore deposits. When the deposition was by
direct replacement of limestone below the level of ground water, the
iron was probably in the form of carbonate, changing to limonite as
the ground-water level was gradually lowered with the progress of
erosion. At a few points the limonite deposit has been traced down-
240 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
ward directly into the unchanged carbonate. This is well shown in
the Sugar Hill deposits, later discussed. From the distribution of the
ore banks it will be seen that a large proportion of them are located
near the contact of the Beaver limestone and the Weisner quartzite.
These generally belong to this class of concentration ores ; and this
contact is marked by a more or less continuous band of ore deposits.
The red clay in which they are embedded is chiefly derived from the
limestone; and the surface is generally covered with fragments of
quartzite from the higher portions of the quartzite ridges.
4. As already remarked, the quartzite has been considerably folded
and is doubtless also intersected by numerous faults of small throw, the
evidence of the faulting being chiefly the occurrence of breccias. The
latter usually consist of fine angular fragments of quartzite cemented
by limonite; and associated with these breccias are often found con-
siderable deposits of iron ore. These are sometimes irregular deposits
embedded in the residual material which covers the surface, and are
not sharply differentiated from the concentration deposits above
described. In other cases, the ore appears to form well-defined fis-
sure veins, with distinct walls of the inclosing formation. This is
notably the case at the Wheeler bank, about 4 miles southeast of Car-
tersville. The vein is from 12 to 15 feet in width, with occasional off-
shoots. The inclosing rock is a gray siliceous schist, with some blue
curly talcose slate and quartz stringers; also occasional bands of
schistose deldspathic conglomerate. The vein dips east about 80° and
strikes neatly north and south, parallel with the schistosity of the
inclosing rock, and with the adjacent Cartersville fault. The ore
appears in part to have filled an open fissure and in part to have
replaced the schist, numerous fragments of which remain in the ore
body. It consists for the most part of geoidal shells, containing many
cavities with stalactitic and botryoidal forms, which have glazed sur-
faces showing brilliant iridescent colors. It generally has a fibrous
structure, and further differs from the concentration deposits in the
almost complete absence of residual clay associated with the ore.
This ore body has evidently been deposited subsequent to the devel-
opment of schistosity in the inclosing rocks, since it shows no evidence
of movement in the way of brecciation or slickensides.
At no point in this district has development gone below water level.
The deposits are generally worked only to a depth permitting direct
drainage. Hence, the bottoms of the ore bodies are seldom reached.
Of the depth to which the our classes of deposits enumerated above
extend, it may be stated (1) that the gossan ores are sharply limited
by water level; (2) that the Tertiary gravel ores are generally super-
ficial, the greater part of the deposits being near the surface, below
which they rarely extend more than 30 feet; (3) that the concentra-
tion deposits go considerably deeper, and, under favorable conditions,
may extend to the depth of 100 feet or even more, and (4) that the
hayes and eckel,] IRON ORES OF CARTERSVILLE DISTRICT, GA. 241
deposits associated with faults and formed in fissures are undoubtedly
the deepest of all. If, as appears probable, they were formed b}T solu-
tions ascending from considerable depths, they may extend downward
several hundred feet, although the character of the ore would doubt-
less be found to undergo some change with depth, the oxide being
accompanied by increasing proportions of sulphide and perhaps
carbonate.
The general belief among the ore miners that certain of these brown
hematite deposits are stratified, occupjang a definite geologic horizon,
is, of course, entirely erroneous. Also, the view which has been
helda that in this and adjoining districts the deposits of brown hema-
tite follow the outcrops of particular beds rich in iron is almost equally
erroneous. The present distribution of these deposits, as shown above,
depends entirely upon the geologic structure which determined chem-
ical and physical conditions requisite for their deposition. In all cases
the iron has been transported to a greater or less distance from the
beds in which it was originally disseminated. The specular hematite
above described, and the red hematites which occur at various hori-
zons in the Silurian rocks, belong to an entirely different class of
deposits.
The deposits of brown hematite which are at present best exposed,
and which furnish excellent examples of the type of "concentration
deposits" described above, are those now worked by the Hurt Iron
Company at Sugar Hill. The mines are located about 12 miles north-
east of Cartersville, and 3 miles southeast from Pine Log Village.
Supplies are obtained and ore is shipped over a branch road which
leaves the Western and Atlantic tracks at a point about 3 miles west
of Cartersville.
Occurrence of ores. — Mining is being carried on in a number of
large open cuts, which, with natural exposures in the vicinit}7, permit
a good idea of the structural relations of the deposits to be obtained.
The ore deposits are associated at this point with the upper beds of
the Weisner quartzite (Cambrian). In the vicinity of the mines, the
quartzite beds are seen to lie in a series of low folds, cross folded so
as to form a number of shallow pitching basins. The ore deposits
occur as a mantle over the impervious quartzite strata, and are
in turn often overlain by thin beds of talcose slates, which are com-
monly much decomposed. Taking the Sugar Hill group of mines
as a whole, their ore deposits seem to occupy a fairly regular strati-
graphic position. They appear to have originated by a replacement
of the strata which originally lay between the quartzite and the talcose
slates, by the deposition of iron from surface or underground waters.
a Spencer, J. W., Economic resources of the Paleozoic group of Georgia: Geol. Survey of
Georgia, 1893.
Bull. 213—03 16
242 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
The strata which have been thus replaced may have been thin beds
of impure limestone, or other relatively soluble materials. The con-
centration of the iron-bearing waters at this horizon, and the conse-
quent deposition of their iron, was favored by the solubility of this
replaced bed, and the relative imperviousness of both the underlying
quartzite and the overlying talcose slates. The iron-bearing waters
were probably, in part, merely surface waters, coining to rest in drain-
age basins and there depositing their iron, under favorable conditions
at points where the decay or complete removal of the talcose schists
gave easy access to the soluble bed. Part of the ore deposition, how-
ever, may have taken place through the action of iron-bearing waters
gaining access to the soluble and pervious replaced beds at some
point where these were exposed, and following down these particular
beds, which formed good channels of communication, even under the
areas where the}' were covered by the impervious talcose slates. It
will be evident that the resulting ore deposits, in the two cases, will
differ somewhat in extent. If deposited entirely from surface waters,
the ore deposits could not extend beyond the limits of the drainage
basin in which they were laid down. If deposited from waters flowing
underground, acting under the principles of artesian flow, the deposits
might have a greater extent, reaching under oilier beds, and it the
underground structure was favorable, extending beyond the surface
limits of the minor drainage basin.
The ore deposits in the Sugar Hill group of mines usually vary
between 5 and 10 feet in thickness, occasionally passing these limits.
The ore commonly carries 50 to 55 per cent metallic iron, and about 1
per cent of phosphorus.
IRON-ORE DEPOSITS OE THE CRANRERRY DISTRICT, NORTH
CAROLINA-TENNESSEE."
By Arthur Keith.
MAGNETITE.
Deposits of magnetic iron oxide occur along a line passing through
Cranberry in a northwest direction. The ore has long been worked
at Cranberry and produces iron well known for its purity. Beginning
near Old Fields on North Toe River, the magnetite has been traced
with small intervals, south of Smoky Gap, through Cranberry, and
on to Shell Creek in Tennessee. This line of outcrop lies in the
Cranberry granite, which is in places mashed and metamorphosed so
as to resemble gneiss, and it is nearly parallel to the boundary of the
granite and Roan gneiss, a relation which is repeated in other districts
toward the west.
At the Cranberry mines open cuts have been made at intervals
over an area 000 by 300 feet and through a vertical distance of 250
feet. From these tunnels are run in for considerable distances. The
ore occurs as a series of lenticular bodies of magnetite in a gangue of
hornblende, pyroxene, epidote, with a little feldspar and quartz, and
a few unimportant minerals. The ore and gangue occur as a series
of great lenses dipping toward the southwest at angles of 45° to 50°,
about parallel to the planes of schistosity in the gneiss. The ore is
found in the gangue in the shape of smaller lenses, dipping southwest
from 40° to 60°. These vary from 50 feet down to a few inches in
thickness, and are from two to five times as long as they are thick.
Sometimes the lenses have sharp limits, but usually the gangue and
ore grade into each other at the contact. Considerable ore is sprinkled
through the gangue, and more or less gangue is scattered through the
ore bodies. The ore is very free from the objectionable elements,
phosphorus and sulphur, though it is not high in iron. It yields an
average of 42 to 4G per cent of iron with ordinary concentration.
Considerable trouble is experienced in freeing the ore from the
gangue before smelting, on account of the tough and refractory nature
given to the mass by the epidote.
Because of the occurrence of the ore as a series of lenses the quan-
(i Abstracted from descriptive text of the Cranberry Geologic Folio, now in press.
243
244 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
tity is rendered more or less uncertain. Each lens will be worked
out in time and its place supplied by other lenses, and to what depth
or distance the occurrences will go on it is quite impossible to state.
The ore bodies may diminish, they may remain about the same, or
they may increase. As judged by openings, tests by diamond drill,
and surface outcrops, the deposit has a length of over a half mile,
carrying bodies of ore throughout that distance. Large quantities of
ore have been taken out, far greater quantities are now in sight, and
there is every reason to expect a large output in the future.
The minerals composing the ore and gangue were deposited at a
time much later than the production of the inclosing rock. They are
also younger than the period of deformation which produced the
schistose arrangement in the granites. The minerals of the ore deposit
are only slightly crushed or rearranged, although they arc the same
varieties which, in adjacent formations, show the greatest metamor-
phism. The ore deposit, therefore, was not due to original segrega-
tion from the igneous granite, but is entirely of a secondary nature.
It may have replaced a preexisting mass of rock by solution and sub-
stitution of new minerals, or it may have been deposited from solu-
tion in open spaces in the inclosing formation. This latter result is
quite unlikely, on account of the great dimensions of the opening
required by the size of the ore deposit. If the deposit represents a
substitution of new minerals for old, the latter were either portions
of the inclosing granite or a mass of a different original character.
The shape of the ore deposits agrees with the general form taken by
the smaller intrusive bodies in this region. The minerals composing
the granite — quartz, mica, and feldspar — are among the least suscep-
tible to chemical alterations. It is therefore probable that the rock
replaced by the ore body had a less simple chemical composition. If
the present minerals represent a recrystallization of those preexisting,
the original rock might well have been a diabase similar to the Lin-
ville metadiabase. This rock contains almost exactly the same min-
erals as the ore deposit, but even the greater alteration through which
it has passed has not produced anything in the nature of an ore.
Accordingly, some additional or separate cause must be sought besides
dynamic altera! ion. An agency fulfilling the conditions, and one thai
is everywhere at work, is water charged with mineralizing agents.
This dissolved and perhaps added to the rock minerals and redeposited
them in favorable places, either in the old or in new chemical combi-
nations. In this case the deposits have not the size or shape of veins,
but are discontinuous and lenticular in shape, as above stated. They
are plainly con trolled and directed by the schistosity of the granite in
this and many other areas toward the west and southwest.
There is no indication whether or not the channels through which
the solution entered corresponded with the schistosity of the granite,
although such correspondence is probable. In the red feldspathic
keith] IRON ORE OF CRANBERRY DISTRICT, N. C.-TENN. 245
granites near Cranberry small veins and stringers of magnetite are
found at many places. These may represent deposition from the min-
eralizing solutions, where there was no body of readily altered rock
which could have been changed into an ore deposit. Also, northwest
of Cranberry the gangue minerals and even magnetite are developed
in the mass of the red granite along more or less mashed zones.
These perhaps represent the places where alteration was most active;
that is to to say, the actual channels through which the mineralizing
solutions passed.
As to the cause that put into action the mineralizing solution some
suggestions can be made. In many areas the heated solutions and
vapors arising from bodies of intrusive rock have produced mineral
alterations and deposits. As stated above, the magnetite deposits are
later than the folding movements. That is also true of the Bakers-
ville gabbro. These intrusive masses are frequent in the area of
Roan gneiss west and southwest of Cranberry, and the magnetite
bodies swing around their circumference. It is thus suggested that
the magnetites are due to alterations begun by the gabbro intrusions.
Whether true or not in this locality, this explanation does not hold
for the magnetite deposits in Ashe County, for there are no recent
igneous rocks in that area.
Of the source of the iron there is as little evidence. The adjacent
formations, the Cranberry granite and the Roan gneiss, both carry
iron chemically combined in the biotite and hornblende. Solution of
either might furnish the iron. There is, however, no apparent altera-
tion or diminution of the ferruginous minerals in the adjacent granite.
From the Roan gneiss iron might more readily have been obtained on
account of the extreme abundance of hornblende in that formation.
That the mineralizing solutions passed through these formations at
more than one epoch is clear from the existence of a band of titan-
iferous magnetite deposits parallel to and southeast of this band.
These are as regularly titaniferous as the ores of the Cranberry band
are free from that mineral. Inasmuch as the two belts are in close
proximity and each is extensive without overlapping the other, their
depositing solutions were probably active at different times. Still
another period of mineralization left its record in the pegmatite veins
and lenses so common in this region. These, however, were crushed
and distorted during the folding of the strata, and thus are so much
older than the magnetite deposits that they can have no origin in
common.
RED HEMATITE.
This ore is found in one locality in this area, on the east side of
Bull Ruffin Mountain. It occurs in the schistose metarhyolite next
to a fault plane, and it is rather an impregnation of the schist with
hematite than a distinct and pure deposit of ore. Little work has
been done in development of the ore, and its value and amount are
questionable.
246 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
SPECULAR HEMATITE.
Iron ore of this nature is found at several points along the south
slope of Beech Mountain. It is found in a small vein'in black schist,
which occurs as a narrow band in the Cranberry granite about 2 miles
long. The ore appears at several places along this line. It has not
been developed beyond shallow prospecting, so that neither the depth
nor the extent of the deposit is known. In association with similar
black schist beds on Big Ridge, a northern spur of Beech Mountain,
are a number of other veins of specular hematite. These have been
examined only by test pits. In all of these localities the ores exposed
are siliceous. The veins arc of small or only moderate thickness, and
have a steep dip. The course of the veins is nearly east and west,
and is marked by scattered outcrops and fragments of ore. In the
same black schist beds at various points northwest of Beech Moun-
tain these ores are found, indicating a considerable range for the
veins.
BROWN HEMATITE.
Ores of this nature are abundant in the Tennessee district, and
include limonite and various combinations of the oxide and hydrate
of iron. They occur as Lumps ami masses in the residual clays of the
Watauga shale and the Shady limestone, and are most plentiful in
the northeastern pari of the district. Ores of the Watauga shale are
siliceous and present all grades between pure limonite and pure chert.
Masses in this formation at lain a diameter of 6 feet. As a rule they
are not available on accounl of the silica, and only within 2 or 3 miles
of Shoun Crossroads have t hey been found sufficiently pure to be used.
Ores of the Shady limestone are usually very pure, and were worked
in the old forges for many years. The deposits form two classes,
masses scattered irregularly through the limestone clay and ores lying
along the fault planes. The Latter usually contain considerable silica
in the form of sand grains and fragments of Erwin quartzite, and they
grade from good ore through ferruginous breccias into ordinary sili-
ceous and calcareous fault breccias. The deposits in clay are very
pure and have received the greatest development. Like all deposits
of this nature, the amount of ore in the clay varies much. In this
region, however, the ore lumps are distributed with unusual frequency
and regularity. The lumps attain a size as greal as i> and 3 feet, and
the deposits have been tested to a depth of 50 feet. The richest and
most frequent deposits are found in the lower part of the limestone,
near its junction with the Erwin quartzite. Considerable pyrite is
found in the upper layers of the quartzite, and may be the source of
much of the iron. The deposits of ore occupy the S3niclinal basins for
the most part, and may be due to downward concentration toward the
bottoms of the folds. This correspondence of structure and ore
deposits is most striking in Shady Valley just north of the Cranberry
quadrangle.
GEOLOGIC WORK IN THE LAKE SUPERIOR IRON DISTRICT
DURING 1902.
By C. K. Leith.
In the early part of the year there was distributed a general paper
by C. R. Van Ilise on the Iron Ores of the Lake Superior Region, con-
taining a general account of the geology of the region and of the
origin of the ores, and accompanied by small scale maps of some of
the districts.
There have also been sent to press during the year Monograph
XLIII, on the Mesabi iron-bearing district of Minnesota, by C. K.
Leith, and Monograph XLV, on the Vermilion iron-bearing district
of Minnesota, by J. Morgan Clements. W. S. Bayley has spent the
year in the preparation of another monograph, on the Menominee
iron-bearing district of Michigan, which will be published in 1903.
The work in all of these districts has been directed by C. R. Van
Hise.
MESABI DISTRICT.
The Mesabi monograph (XLIII), by C. K. Leith, is a volume of 301
pages, accompanied by a general map of the range, covering the area
between Birch Lake and Grand Rapids on a scale of 1 mile to the
inch, and by 33 plates and 12 figures, including many detail maps
and sketches.
The Mesabi iron ores have developed from the secondary alteration
of a rock composed largely of green ferrous silicate granules, resem-
bling glauconite, and so called by Spurr, but here shown not to be
glauconite and called " greenalite." The greenalite granules are sup-
posed to develop in much the same way as iron carbonates of other
parts of the Lake Superior region, described by Van Hise, and to owe
their occurrence in the form of granules to organic agencies. The
concentration of the ores has consisted essentially in the oxidation,
under weathering conditions, of the ferrous iron in the greenalite
granules and the segregation of the iron and silica. The alteration
of the greenalite and concentration of the ore has occurred through
the agency of moving underground waters and the ore deposits have
been localized in places where the circulation has been vigorous.
Broad, shallow synclines in the iron formation (Upper Huronian) have
exerted a primary control of the circulation of the underground waters
247
1248 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
concentrating the ores, but other factors, the cross fracturing of the
formation affording trunk channels for water circulation and the
ponding of water by impervious slate layers within and above the
iron formation, have had strong modifying effects on the circulation
and have locally been dominant. So important are these modifying
factors and so complex their effect that the ore deposits have most
irregular shapes and erratic distribution, and it is scarcely possible
to indicate from the structure of the iron formation an area which is
more likely than any other to reveal ore on exploration.
The ore deposits are shallow, seldom exceeding 350 feet in depth,
but have great horizontal dimensions, sometimes a mile or more.
The ore bodies come to the rock surface for most of their area, but
are covered with glacial drift to a depth varying from a few feet to
100 feet. The rich ore deposits thus far discovered are confined to
the central part of the district. At the east end of the district the
ores are hard and magnetic and associated with amphiboles, and have
not been shown to occur in bodies large enough to warrant mining.
In the west end of the district some good ore has been found, but
here for the most part the ores are of low grade and contain abundant
chert particles resulting from the disintegration of associated chert,
making it necessary to wash the ores before using them.
The iron formation is overlain to the south by a thick slate forma-
tion. Exploration has not yet shown whether or not ore will be found
beneath this slate, but certain geologic facts indicate small proba-
bility. The boundary between the slate and iron formation as siiown
on the geologic map is, because of the heavy covering of glacial drift,
only approximately correct. Much more exploration will have to be
done before the true limits of the iron formation on the south can be
mapped. The iron formation itself contains interbedded slate hiyers
which closely resemble the slate overlying the iron formation, making
it difficult in individual areas to determine whether the area should
be mapped as iron formation or as overlying slate.
The total tonnage of high-grade ore thus far discovered in the
Mesabi district has been estimated at from 500,000,000 to 700,000,000
tons, a common estimate being 000,000,000 tons, of which nearly 70 per
cent is of Bessemer grade. This tonnage is over twice that of all the
other Lake Superior iron districts combined. The United States
Steel Corporation in 1902 owned and controlled 85 per cent or more of
the Mesabi ore. Shipments from the Mesabi district first began in 1801,
and in 1902 the shipments were nearly half of the total for the Lake
Superior region, namely, 13,329,953 tons, and more than one-third of
the total of the United States.
The ores are mined in open ruts by steam shovel, or underground
by either ordinary or " milling "« methods. In 1 902 about 40 per cent
a Chutes, known as mills, are run from the level of the bottom of the shaft up to the working
levels. The ore is loosened and dumped into the chute, falling into ears at the bottom, being
trammed to the shaft and hoisted.
leith.] WORK IN LAKE SUPERIOR IRON DISTRICT. 24VJ
of the ores was mined by open-pit steam shovel, 46 per cent by ordi-
nary underground methods, and 7 per cent by " milling."
When lirst introduced Mesabi ores were considered too soft for
extensive use in furnace charges, but now they constitute an average
of 50 per cent of the ore burden, and individual ores may be used in
percentages as high as 100 per cent.
The iron and water content of the Mesabi ores is greater than in the
other ores of the Lake Superior region. The phosphorus in the ores
(determining their Bessemer or non-Bessemer character) is shown to
have been introduced into the ores by percolating waters during the
concentration of the ore and not to be a residual product of alteration.
The precipitation of phosphorus from percolating waters is believed to
be connected in some way with aluminous compounds in the ores.
VERMILION DISTRICT.
The Vermilion monograph (XLV), by J. Morgan Clements, is a vol-
ume of 403 pages, accompanied by a general map of the Vermilion
range covering the area from west of Tower to Gunflint Lake, an atlas
of 24 detail maps, and 13 plates and 23 figures in text.
The iron ores are shown to be confined to the Basement Complex
or Archean, to be closely associated" with jasper and greenstone, and
to have been concentrated by underground waters in steep pitching
troughs formed by the folding of the greenstone. No direct evidence
of the original source of the ore has been found, but it is believed
that the iron has developed from an iron carbonate, in this feature
resembling the old ranges of the Lake Superior region rather than
the Mesabi range.
The ores are hard, blue and red hematites, and up to the present
time have been found in large quantities in only two areas in the
district — near Soudan and near Ely. The detail maps show iron-
formation belts at man}^ other places in the district in which explora-
tion is warranted.
MARQUETTE, GOGEBIC, AND CRYSTAL FALLS DISTRICTS.
At the completion of work in the Mesabi district in 1902, C. K.
Leith, with the direction and assistance of C. R. Van Ilise, took up
the revision of the published geologic maps of the Marquette, Gogebic,
and Crystal Falls districts with the jmrpose of preparing for publica-
tion corrected editions showing the results of the vast amount of
recent exploration, and with the further purpose of combining the
geology shown on these maps in a large geologic map of the Lake
Superior region, including all of the iron districts, to accompany a
final monograph of Lake Superior geology to be submitted in 11)04 by
C. R. Van Ilise, with the assistance of C. K. Leith. Many changes
in the boundaries of the iron formal ions in the differen! districts
250 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
were noted. Facts were collected that seemed to indicate that the
phosphorus in these districts, as in the Mesabi district, is the result
of the concentration of the percolating waters rather than a residual
product, and that the precipitation of the phosphorus from such
waters may be in some way connected with aluminous compounds in
the ore, notwithstanding the fact that some of the phosphorus is now
present in the ores as apatite, as shown by Prof. A. E. Seaman, of
the Michigan School of Mines.
MOOSE MOUNTAIN DISTRICT.
Late in the season a visit was made to the new iron-bearing dis-
trict, the Moose Mountain district, northeast of Lake Superior. Mag-
netite ore was observed in large quantities. This is the first district
in which iron ores in large quantity have been discovered in Canada.
The district in its geologic features resembles the Vermilion of Min-
nesota more closety than any other district, and because of this
resemblance the Moose Mountain iron-bearing rocks are supposed to
be of Archean age, although no structural connection of the two dis-
1 nets is possible. The ores are closely associated with quartzites and
graywackes bearing iron pyrites, and alterations of iron pyrites to
iron ore may be observed on a small scale, and these facts, together
with the abundance of other sulphide ores in this area, lead us to sus-
pect that further work may sho*vr llie origin of the iron ores to be in
some way connected with the iron pyrites.
MANGANESE DEPOSITS OF SANTIAGO, CUBA/
By Arthur C. Spencer.
The deposits of manganese which have thus far been worked in
Cuba are all located in the vicinity of the city of Santiago, in the
province of the same name, which is the easternmost on the island.
The first ore, shipped in 1887, was a picked lot of 50 tons, and in spite
of adverse conditions in regard to facilities for transportation, the
output had increased by 1890 to 21,810 tons. From this time up to
1898 the amount of ore annually mined was not so great, but various
deposits were discovered and several mines were opened with varying
success. As many as eight mines, which were worked previous to the
revolution of 1895-1898, have been visited by the writer.
The manganese ores of the Santiago region are mixtures in various
proportions of the common oxides of manganese, probably including
manganite, pyrolusite, braunite, and wad. The deposits occur in a
region lying back of and parallel to the Sierra Maestra, between
Guantanamo on the east and Manzanillo on the west, and in general
coincident Avith the drainage basins of the Rios Cauto and Guan-
tanamo. The geologic structure between the latitudes of the two
cities named is that of a broad synclinal fold, with an east-Avest axis.
From Cabo Cruz on the Avest to Guantanamo on the east the stratified
rocks which compose the northern slopes of the Sierra Maestra dip at
angles of from 10° to 20° toward the depressed area of the interior
occupied by the Rios Cauto, Guaninicum, and Guantanamo, Avhile
upon the north side of these drainage basins the strata rise as the
mountains which occupy the country between them and the north
coast are approached. The rocks exposed along the crest of the Sierra
Maestra are coarse, well-stratified volcanic breccias, but upon the
northern slope these soon jmss beneath strata showing an alternation
of marine sediments and fine-grained volcanic tuffs, which are in turn
covered by flows of basalt and still other f ragmental Arolcanic deposits.
This essentially volcanic series grades into and finally gives place
lo limestones and other purely marine sediments, as may be well
observed along the neAv military road which crosses the high range of
hills north of Santiago Bay, and at Cristo, Avhere the Moroto and
"Report on a geological reeonnoissanee of Cuba, made under direction of Q-en. Leonard Wood,
military governor; also Eng. and Min. Jour., August :.':», L903, pp. 62-69.
251
252 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
Sabanilla Railway crosses the same range in a deep notch or pass.
On both sides of the railroad south of this pass there are several old
manganese mines in rocks belonging to the upper part of the mixed
volcanic and marine series. The manganese was also formerly
worked near the station of Dos Bocas, several miles west of the
deposits located south of Cristo, and apparently in rocks occupying
approximately the same stratigraphic position. The beds exposed in
these mines are very much disintegrated, and the rock is frequently
impregnated to a considerable extent by manganese ore. It is varie-
gated in its coloring, being green with red splotches. It exhibits no
gritty material, and it appears to have been made up of fragments
which were originally angular in form. At the Boston mines, located
between 2 and 3 miles to the east of Cristo, the country rocks are
limestones and glauconitic greensands, cemented by lime, and both
of these rocks are found replaced by ore. When decomposed they
resemble the disintegrated beds south of Cristo.
In the deposits south of the Cristo divide, between the drainage
which flows directly to the sea by way of Rio San Juan and the basin
of the Rio Cauto, which finds its outlet to the west of Cabo Cruz, the
strata all dip at varying angles toward the north, excepting in such
instances as they are overturned, when the reversed dips are very
steep toward the south. Associated with the ore there are large
amounts of siliceous rock in the form of dense amorphous jasper, or
bayate, as it is locally called. Traced in a broad way, the bayate
may be made out to follow the stratification of the bedded rocks,
along which it occurs in interrupted masses. But studied locally, the
irregularity of the bayate is such that, with the poor exposures of
the strata which exist, it would be impossible to say that it did not
have the form of cross-cutting veins, as sometimes appear. However,
the interbedded character of the siliceous rock is established with a
good degree of certainty. Across the stratification the thickness of
the jasper masses is found to vary from a few inches to 15 or 20 feet,
while along the bedding they may have a length reaching in some
cases several hundred feet.
The ore occurs principally in a very irregular way, filling spaces
between the jasper and the country rock, but also in the form of veins
in the masses of jasper, and disseminated through the decomj)osed
country rock adjacent to the jasper. In the last case the ore frequently
has the form of nodules arranged in the bedding planes of the parent
rock, which it seems to have replaced in part. The relations of the
ore and the jasper are very intimate, and specimens may be found
in which veinlets of ore penetrate the jasper as though there had
been molecular replacement of the latter by the former. On the other
hand, cases may be observed in which the opposite condition seems
to have obtained, so that the ore wras replaced by siliceous material
introduced after the first deposition of the metallic mineral. In gen-
spencer.] MANGANESE DEPOSITS OE SANTIAGO, CUBA. 253
eral the mode of occurrence is such that both the ore and the associ-
ated jasper appear to have been introduced in a secondary way after
the deposition of the strata in which they are found and the original
substance of which they now replace. The jasper and the oxides of
manganese are of contemporaneous origin, and for their introduction
into the strata where they now occur the action of the heated water
in circulation is suggested. The constitution of the greensand beds
was evidently favorable for a chemical reaction between their substance
and the materials held in solution by ascending hot waters, which
doubtless, originating at a considerable depth, found easy channels
of outlet through the more porous of the disturbed and upturned
strata occurring in the region.
Oilier manganese mines, and in fact the only ones at present in
operation, lie about 3 miles east of Cristo, and 12 miles to the north-
east of the same town. The former comprise the Boston group of
claims already mentioned and the Ysabellita near by, and the latter
includes the Ponupo mines. Owing to the limited time at the writer's
disposal it was impossible to sufficiently test the theory formed in the
field that all of these deposits lie at approximately the same geo-
logic horizon. There are, however, some facts which tend to sup-
port this idea. Perhaps the most important of these is the occurrence
of a band of limestone, composed almost entirely of foraminifera
belonging to the type Oi'bitoides, just above the ore horizon at four
distinct and widely separated localities, namely, near the mines cast
of the railroad south of Cristo, at the Boston mines, at the Ponupo
mines, and at San Nicolas, about 8 miles west of San Luis, where
manganese ores also occur in green, disintegrated sandstones. Again,
in almost all of the places where the strata in which the ores occur
are exposed, they are exactly similar, being loose, disintegrated sand-
stones, mostly of a dark green color. At the Boston mines the green,
decomposed sandstones have been uncovered at a short distance from
the ore body, and here, though resembling in general appearance the
sand which occurs with much of the ore, they are found to be made
up in large part of the shells of a large variety of foraminifera filled
with glauconite and accompanied by grains of the same mineral to
which the green color of the sandstone is due. It seemed evident that
these rocks and the ore-bearing beds were originally of the same
nature, but that the calcareous shells of the foraminifera had been
removed from the near neighborhood of the ore deposits by the solu-
tions which deposited the silica and manganese. A similar removal
of the calcareous contents may be taken to explain their absence from
the other localities, where the only strata observed were those in
close proximity to the ore bodies and jasper.
The rocks in the region south of Cristo were found to have been
tilted toward the liQrth, as though they were lying upon the south side
of a great structural syncline. This, in fact, they do, as more gen-
254 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
eral observations in Santiago province show. The structure in the
immediate vicinity of the Boston and Ponupo mines is quite dif-
ferent. These lie well within the great syncline, where the strata
have been thrown into minor folds, and it is observed that the ore
deposits in both places occupy the central or axial portion of articlines
or arches of the strata. The Ysabellita mine is less than a mile from
the Boston, and appears to be located upon the same arch, but the
structural relation between this fold and the one at the Ponupo mine
is not known. Though the altitude of the strata is different, the
relations of the ore, jasper, and country rock are exactly the same as at
Cristo, and the deposits have been the result of metasomatic replace-
ment of calcareous strata by manganiferous minerals and jasper. In
the case of the Boston, Ysabellita, and Ponupo mines, and probably also
at San Nicolas, it may be argued that the hot waters to which the
-replacement is attributed ascended through rissures locally developed
along the axis of the folds rather than through the strata, as has been
suggested for the occurrences in the vicinity of Cristo, where the
stratified formations are standing on end. This would account for the
local character of the deposits along the folds, as well as the presence
of undissolved shells and the absence of both jasper and ore in the
beds of green sand as they rest on the flanks of the arch at the Boston
mines.
In both the Boston and Ysabellita mines the amount of jasper is
large, and it occurs in large masses, around which the richest ore is
found, with deposits in which the ore is mixed with rock, dissemi-
nated locally in the portions of the decomposed greensand or glau-
conitic rock adjacent to the jasper. Sometimes the ore is found to
entirely surround the masses of siliceous rock along its contact with
the country rock. An illustration of this is seen in the Boston mine,
where a large block of jasper has been worked about on all sides and
a large amount of ore extracted. Another is seen in the workings of
the Ysabellita mine. Next to the large mass of jasper a bed of
loose, sandy material, containing oxide of manganese in the form of
small nodules arranged along the planes of stratification, extends to a
distance of not less than 25 feet from the jasper, and the thickness
of the ore-bearing bed is not less than 20 feet as exposed.
In this vicinity there are no less than six distinct outcrops of jasper
in large masses within a radius of about 150 feet, but only one has
been sufficiently developed to prove the presence of large quantities
of ore.
At the Ponupo mine the conditions are quite similar to those at the
two mines just mentioned. The deposit occupies the center of an
anticlinal fold, and there are large amounts of jasper, with high-grade
ore occurring in contact with it, and ores of lower grade, because
mixed with decomposed rock lying adjacent to it. Here the ore
extends up to the horizon of the foraminiferal limestone, which it
spencer] MANGANESE DEPOSITS OF SANTIAGO, CUBA. 255
has replaced in part, as was well seen upon the north side of the mine.
The ores in these three mines occur about the summits and slopes of
knolls which owe their elevation to the durability of the jasper against
the processes of erosion. This jasper occurs in very irregular masses,
between which the ore is found in equally irregular pockets, either
pure, or, as has been stated, mixed with decomposed country rock.
Frequently the ores are intimately veined or impregnated with streaks
of jasper, when they become valueless, but as a rule the jasper occurs
in well-defined nodules, which may be easily separated from the rock,
which must be mined with the ore.
The mode of occurrence in all of the localities mentioned is such
that very large deposits can not be expected. A yield of 100,000 tons
of first-grade ore from any one mine is estimated as all that can be
expected in most cases, though if the attempt now being made to con-
centrate the ores at the Boston mine is successful the marketable out-
put will be greatly increased.
The Ponupo mine has been worked on a large scale since the winter
of 1898. It has standard-gage tracks laid to the ore chutes. A track
has also recently been completed to the Boston mine, and can readily
be connected with the Ysabellita. It is from these mines that the
supply of Cuban manganese will be drawn for some time, though with
the completion of the Cuba Central Railway a few other mines of
importance may be developed. The amount of ore which ma}^ be
anticipated from any one of them will not, however, warrant the
construction of special tracks of any great length to bring their
product to the trunk line.
PUBLICATIONS ON IRON AND MANGANESE.
A number of the principal papers on iron and manganese ores pub-
lished by the United States Geological Survey, or by members of the
Survey, are listed below:
Barus, P. The present technical condition of the steel industry of the United
States. U. S. Geol. Survey Bulletin No. 25, 85 pp. 1885. (Out of print.)
Birkinbine, J. American blast-furnace progress. In Mineral Resources U. S.
for 1883-84, pp. 290-311. 1885.
The iron ores east of the Mississippi River. In Mineral Resources U. S.
for 1886, pp. 39-98. 1887.
The production of iron ores in various parts of the world. In Sixteenth
Ann. Rept. U. S. Geol. Survey, Pt. Ill, pp. 21-218. 1894.
Iron ores. In Nineteenth Ann. Rept. U. S. Geol. Survey, Pt. VI, pp.
23-63. 1898.
Manganese ores. In Nineteenth Ann. Rept. U. S. Geol. Survey, Pt.
VI, pp. 91-125. 1898.
Chisolm, F. F. Iron in the Rocky Mountain division. In Mineral Resources
U. S. for 1883-84, pp. 281-286. 1885.
Clements, J. M. The Vermilion iron-bearing district of Minnesota. Mono-
graph U. S. Geol. Survey Vol. XLV. 463 pp. 1903.
Clements. J. M., Smyth. H. L., Bayley, W. S.. and Van Hise, C. R. The
Crystal Falls iron-bearing district of Michigan. Monograph U. S. Geol. Survey
Vol. XXXVI, 512 pp. 1899.
Hayes, C. W. Geological relations of the iron ores in the Cartersville district,
Georgia. In Trans. Am. Inst. Min. Eng., Vol. XXX, pp. 403-419. 1901.
Irving, R. D., and Van Hise, C. R. The Penokee iron-bearing series of Michi-
gan and Wisconsin. Monograph U. S. Geol. Survey Vol. XIX, 534 pp. 1892.
Kemp, J. F. The titaniferous iron ores of the Adirondacks [New York]. In
Nineteenth Ann. Rept. U. S. Geol. Survey, Pt. III. pp. 377-422. 1899.
Leith, C. K. The Mesabi iron-bearing district of Minnesota. Monograph
U. S. Geol. Survey Vol. XLIII. 316 pp. 1903.
Smith, E. A. The iron ores of Alabama in their geological relations. In Min-
eral Resources U. S. for 1882, pp. 149-161. 1883.
Smith, Geo. O. , and Willis, B. The Clealum iron ores, Washington. In Trans.
Am. Inst. Min. Eng., Vol. XXX, pp. 356-366. 1901.
Spencer, A. C. The iron ores of Santiago, Cuba. In Eng. and Min. Jour. , Vol.
LXXII, pp. 633-634. 1901.
Swank. J. M. The American iron industry from its beginning in 1619 to 1886.
In Mineral Resources U. S. for 1886, pp. 23-38. 1887.
Iron and steel and allied industries in all countries. In Sixteenth Ann.
Rept. U..S. Geol. Survey, Pt. Ill, pp. 219-250. 1894.
Van Hise, C. R. , Bayley, W. S. , and Smyth, H. L. The Marquette iron-bearing
district of Michigan, with atlas. Monograph U. S. Geol. Survey Vol. XXVIII,
608 pp. 1897.
Weeks, J. D. Manganese. In Mineral Resources U. S. for 1885, pp. 303-356. 1886.
Manganese. In Mineral Resources U. S. for 1887, pp. 144-167. 1888.
Manganese. In Mineral Resources U. S. for 1892, pp. 169-226. 1893.
Yale, C. G. Iron on the Pacific coast. In Mineral Resources U. S. for 1883-84,
pp. 286-290. 1885.
In addition to the papers listed above, iron deposits of more or less
importance have been described in the following geologic folios (for
location and further details see pp. 11-13) : Nos. 2, 4, 5, 6, 8, 10, 11, 12,
14, 18, 10, 20, 21, 22, 24, 25, 28, 32, 33, 35, 36, 37, 40, 43, 44, 55, 56, 59,
61, 62, 64, 70, 72, 78, 82, 83, 84.
256
COAL.
The first paper presented below is a reprint, in slightly condensed
form, of the introduction to the series of special reports on the coal
fields of the United States, published in 1902/* It is republished
here to serve as a summary of the subject for this volume. Fol-
lowing it will be found two reports, hitherto unpublished, on the
results of field work b}^ the Survey during 1002 in the coal fields of
Pennsylvania, Indiana, and Illinois, and of Alaska. Field work was
also carried on by the Survey in other coal districts, but the results
are not now in shape for publication.
The series of reports on United States coal fields above mentioned
covered the entire coal industry of the country. Owing to the length
and importance of these reports, it is impossible to present satisfac-
tory abstracts of them in this bulletin. For detailed information in
regard to the various fields it will be necessary, therefore, for the
reader to consult the reports themselves.
COAL FIELDS OF THE UNITED STATES.
By C. W. Hayes.
DISTRIBUTION OF COAL IN THE UNITED STATES.
Coal occurs in commercial quantities in 27 of the 47 States and Ter-
ritories of the United States and in Alaska. The following table
shows the areas of coal-bearing formations in the several States and
the rank of the coal-producing States in area and production:
Rank of coalfields and coal-producing States hi area and production.
Area of
coal-
bearing
forma-
tions.
Per
cent
prob-
ably
pro-
duc-
tive.
Rank
of
field
and
State
in area.
1900.
Coal field, and State or Territory.
Produc-
tion.
Aver-
age
price
per
ton at
mine.
Per
cent of
total
pro-
duc-
tion.
Rank
in
pro-
duc-
tion.
Anthracite field:
Sq. miles.
rows.
98,404
57,367,915
$1.40
0.04
21.25
Pennsylvania
484
26
1
X
Atlantic coast Triassic:
Virginia
270
800
50
(?)
30
24
J 57,912
North Carolina
1.79
Total
1,070
VIII
57.912
"Twenty-second Ann. Rept., Pt. III. For a list of Survey's publication on coal, see p. 294.
Bull. 213—03 17 257
258
CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
Rank of coal fields and coal-producing States in area and production — Cont' d.
Area of
coal-
bearing
forma-
tions.
Per
cent
prob-
ably
pro-
duc-
tive.
Rank
of
field
and
State
in area
1900.
Coal field, and State or Territory.
Produc-
tion.
Aver-
age
price
per
ton at
mine.
Per-
cent ol
total
pro-
duc-
tion.
• Rank
in
pro-
duc-
tion.
Northern Appalachian:
Sq. miles
15, 8(H)
12,000
510
1,850
17,280
10,300
75
70
80
80
75
70
10
25
22
6
13
Tons.
79,842,32(5
18,988.150
4,024, CSS
2,353,576
22,647,207
2,222,867
.97
1.02
.98
.89
.81
.92
29. 58
7.03
1.49
.87
8.39
.82
1
4
11
17
3
18
Ohio
West Virginia
Kentucky (eastern)
Total
57,740
III
1:50,078,814
Southern Appalachian:
Tennessee
4,400
167
8,500
47
14
N
18
31
15
3,708.5(52
315,557
8,394,275
1.14
1.17
1.17
1.38
.12
3.11
13
26
5
Georgia.
Alabama
Total..
13,067
VI
12,418,394
Northern Interior:
Michigan
11,300
(?)
12
849,475
1.48
.31
25
VII
Eastern Interior:
Indiana
9,300
42,900
5,800
60
50
65
13
1
17
6,484,086
25,767,981
3,106,097
1.03
1.04
. 92
2.40
9. 55
1.15
6
2
15
Illinois
Kentucky (western)
Total
58,000
II
35,358,164
Western Interior:
Iowa
20,000
23,000
3,200
20,000
50
60
75
4
2
lit
3
5,202,939
3,540,103
1.38
1.21
1 . 9:5
1.31
9
14
Missouri .
Nebraska
Kansas
4.4(57,870
1.22
1.65
10
Total
66,200
I
1:5.210.912
Southwestern:
Indian Territory .
14, 848
1 . 728
11,300
50
75
45
8
23
11
1,922,298
1,447,915
968,373
1.45
1.14
1.63
.71
.54
.:«;
19
21
24
Arkansas
Texas
Total
27,876
V
4,338,616
Rocky Mountain:
South Dakota...
120
L3,000
32
9
129,883
1,(5(51,775
10
4,014,(502
1,147,027
5,182,176
1,263,083
1.22
1.63
5.00
1. 36
1.2(5
1.12
1.37
.05
.(52
1.49
.42
1.92
.47
28
20
30
12
Montana
Idaho
Wyoming.,
7,500
2,000
18,100
2,890
50
30
50
40
16
21
5
20
Utah.
Colorado . . .
23
New Mexico
8
22
Total
43,610
IV
13,398,556
Pacific coast:
Washington
450
320
280
27
28
28
2,474,093
58,864
171,708
1.90
3.74
3.05
.92
.02
.07
Oregon.
16
California.
29
27
Total
1,050 .
IX
2,704,665 .
hayes] COAL FIELDS OF THE UNITED STATES. 259
Areas of lignite-bearing formations are not included in the above
table. These areas are extensive and their beds of lignite contain a
vast reserve of valuable fuel, but they are not strictly comparable
with the higher-grade fuels of the anthracite and bituminous fields.
There are approximately 56,500 square miles of lignite-bearing forma-
tions, chiefly Cretaceous, in Montana, the Dakotas, and Wyoming.
The Tertiary lignite-bearing formations of Alabama, Mississippi,
Louisiana, Arkansas, and Texas constitute another area of about
equal extent. The percentage of the areas of coal-bearing formations
which is probably productive is fairly well known in a few of the
thoroughly developed fields. In most of the fields, however, the figure
given is merely an estimate based on incomplete data, while in a few
the available data are of such a character that an estimate would
have little if any value. The estimates given are believed to be con-
servative in eveiy case. It should further be remembered that large
areas which under present conditions are, for various reasons, classed
as unproductive, may in the future, under changed conditions, become
productive. This is the case with those fields in which the coal lies
too deep to be mined with profit at the present time.
The true rank of the several coal fields and States in value of the
available fuel which they contain is not indicated by the table, since
area of coal-bearing formations and percentage of productive area are
only two of the factors which determine that value. Other factors
are the number and thickness of the workable beds of coal, its quality
as fuel, and the ease with which it can be mined. The data are not
at present available for bringing these factors into the problem.
It will be noted that the rank of the States in production is quite
different from their rank in area of coal-bearing formations. Thus the
Northern Appalachian field, which ranks third in area, ranks first in
tonnage and value of product, while the Western Interior field, which
ranks first in area, is fourth in production. This result is due to sev-
eral causes, among the most important of which are (1) proximity to
markets, (2) suitability of the coal to the fuel requirements, (3) rela-
tive quantity of workable coal per square mile of productive area.
GEOLOGIC RELATIONS OF THE COAL FIELDS.
The coal-bearing formations of the United States range in age from
Carboniferous to Tertiary. The Carboniferous coals are confined to
the region east of the one hundredth meridian and the Triassic coals
to the Atlantic coast. Most of the Cretaceous coal fields lie in the
Rock}^ Mountain region, between the one hundredth and one hundred
and fifteenth meridians, and the Tertiary coal fields are between the
one hundred and twentieth meridian and the Pacific coast. During
the three great coal- forming periods, therefore, the Carboniferous,
the Cretaceous, and the Tertiary, there has been a successive west-
ward shifting of the zone within which conditions favorable for the
260 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
accumulation of coal prevailed. Exceptions to this westward pro-
gression of the coal-forming zone were the deposition of coal east of
the Carboniferous fields in Triassic time and south of the Carbonifer-
ous fields during Tertiary time.
Carboniferous coal fields. — There are five main subdivisions of the
Carboniferous coal fields. They may be briefly characterized as
follows :
The anthracite field is confined to eastern Pennsylvania and con-
tains 484 square miles of productive area. It consists of several long,
narrow, synclinal basins, whose axes are approximately parallel,
extending in a northeast-southwest direction. They do not differ
materially from the ordinary synclines of the sharply folded Appa-
lachian belt, except that they are sufficiently deep to have preserved
the Coal Measures, which have elsewhere throughout this folded belt
been generally removed by erosion in the synclines as well as upon
the anticlines. This field has been thoroughly developed, and a larger
proportion of its coal has been mined than of any of the other fields.
The Appalachian field, which has been subdivided into northern
and southern fields, extends from the northern border of Pennsylvania
southwestward 850 miles to central Alabama. It embraces portions
of nine States, and contains, approximately, 70,800 square miles, of
which about 75 per cent contains workable coal. The eastern margin
of this field forms the western border of the sharply folded Appala-
chian belt, and along this margin the strata have suffered some fold-
ing, a few outlying synclines being nearly or quite separated from the
main field by steep eroded anticlines. In general, however, the strata
in this field are either gently undulating or essentially horizontal.
The formations which make up the Coal Measures are generally
thickest along the eastern margin of the field, thinning rapidly west-
ward. In the same direction there is a corresponding decrease in
number and thickness of the coal beds. These formations consist of
overlapping lenses of conglomerate, sandstone, shale, coal, and occa-
sionally limestone, none of which can be traced throughout the entire
field. Some coal beds, as the Pittsburg and Sewanee, may be identi-
fied over several thousand square miles, but more generally the work-
able coal is in local thickenings of beds that are elsewhere worthless.
For this reason correlations of individual beds in distant parts of the
field are of doubtful value, although particular horizons may often be
closely correlated by means of the fossil plants they contain. Some
portions of the field have been carefully prospected, chiefly those hi
which development has been most active, but large areas, particularly
in West Virginia and Kentucky, remote from lines of transportation,
remain practically unknown.
The Northern Interior field lies wholly within the State of Michigan
and has an area of approximately 11,000 square miles. It forms an
oval area Avhose outlines are imperfectly known, since the region is
HAYES.] COAL FIELDS OF THE UNITED STATES. 261
deeply covered by glacial drift. Prospecting is done entirely by
means of the drill, and on account of the expense involved the pro-
portion of the field underlain by workable coal can not at present be
estimated. The strata appear to dip from the margins of the field
toward its center, the formations thickening in the same direction.
It is probable that this field was formed in an isolated basin and that
its strata have never been continuous with those of the fields to the
southeast and southwest, in Ohio and Indiana.
The Eastern Interior field embraces portions of Indiana, Illinois,
and Kentucky, having an area of 58,000 square miles. It forms an
oval basin whose longer axis extends northwest and southeast, nearly
at right angles to the axis of the Appalachian field. The strata about
the margins of the basin have gentle dips toward its center, while in
the interior of the basin they are practically horizontal. The work-
able coal beds are confined to the lower portion of the Coal Measures,
and hence reach the surface in a broad belt about the margins of the
basin. The development of the field has been confined to this belt,
although the coal beds are supposed to extend beneath the unproduc-
tive formations which occupy the surface in the central portion of the
field. It is estimated that about 55 per cent of the area is productive
under present conditions, and that a considerable proportion of the
remainder will become productive when conditions render mining at
greater depths profitable. The Eastern Interior field is separated
from the fields on either side by broad, gentle anticlines, from which
the Coal Measures, which may originally have been continuous, have
been removed by erosion.
The Western Interior and Southwestern fields form a practically
continuous belt of Coal Measure rocks extending from northern Iowa
southwestward 880 miles to central Texas, and embrace an area of
94,000 square miles in Iowa, Missouri, Nebraska, Kansas, Indian
Territory, Arkansas, and Texas. At the eastern margin of these
fields the underlying older formations reach the surface, while along
their western margin the Coal Measures pass beneath the Permian
and other formations of the plains region.
In the Western Interior field and the northern portion of the South-
western in Indian Territory, as well as in the portion lying in Texas,
the strata are nearly horizontal, having a uniform gentle dip to the
west. In that portion of the field which lies in Arkansas and extends
westward through the central part of Indian Territory the strata are
somewhat sharply folded. This belt forms the northern border of the
intensely folded and faulted Ouachita Mountain zone, whose structure
corresponds closely with that of the Appalachians.
Triassic coal fields. — Several small basins of Triassic rocks in the
Piedmont region of Virginia and North Carolina are coal bearing.
They contain an aggregate area of about 1,000 square miles. The
most important of these, and the only ones at present productive, are
262 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
the Richmond and Deep River areas. The strata of these basins rest
directly upon the crystalline rocks of the Piedmont Plateau. They
may originally have been continuous and nearly horizontal, but are
now separated and considerably folded and faulted. They have also
been invaded by dikes and sheets of igneous rocks, which have at some
points converted the coal into natural coke or carbonite. While the
coal is in some places of excellent quality, it shows great irregularity,
as would be expected from the conditions under which it was depos-
ited and the movements to which it has subsequently been subjected.
These fields are chiefly of historic interest, since the first systematic
coal mining in the United States was carried on within their borders.
Cretaceous coalfields. — As conditions had been favorable for the
accumulation of coal in the region east of the one hundreth meridian
during Carboniferous time, so thejr were favorable for its accumula-
tion during Cretaceous time in the region between the one hundredth
and one hundred and fifteenth meridians. Since the deposition of the
Cretaceoiis formations in this region it has been subjected to the
action of mountain-building forces and to intense volcanic activity.
Hence the coal-bearing formations, which may originally have been
continuous over much of this region, occur in small, irregular basins
separated by larger areas of elevation and erosion or by areas of igne-
ous rocks. Although the folding of the strata and their invasion bj^
igneous rocks have greatly reduced the area of the coal-bearing forma-
tions, the quality of the coal has been thereby greatly improved. In
the extensive undisturbed Cretaceous areas which extend eastward
from the Rocky Mountains beneath the plains region in Montana,
Wyoming, and the Dakotas, there are numerous beds of lignite, while
the same horizons on the flanks of the mountains yield high-grade
bituminous coal.
The Cretaceous coal fields are included within a belt that extends
from the Canadian boundary southeastward for a distance of 1,200
miles. Its axis coincides with the main range of the Rocky Moun-
tains, but includes also numerous outlying ranges. Its greatest
breadth is about 500 miles. It embraces portions of Montana, South
Dakota, Wyoming, Colorado, Utah, and New Mexico. Mr. Storrs has
described 45 separate areas within this belt, having an aggregate extent
of 43,010 square miles/' All of these areas are known to contain work-
able coal, but many of them are undeveloped and practically unex-
plored, so that estimates of the productive area are not by any means
exact.
Two small areas of Cretaceous coal-bearing formations in western
Texas properly belong with the Rocky Mountain fields. The west-
ernmost of these is the San Carlos coal field, in El Paso County.
Considerable outlay has been made here in development, but all the
a Twenty-second Ann. Eept. U. S. Geol. Survey, Pt, III, p. 422.
hayes.] COAL FIELDS OF THE UNITED STATES. 263
coal thus far discovered is a low-grade fuel, and the field is not now
producing. The Eagle Pass field is much the larger and more iinpor-
1 taut of the two, and contains some coal of excellent quality. It
extends from the northern border of Uvalde County about 75 miles
southwestward to the Rio Grande, and beyond the international
boundary expands to a broad area in Mexico. The strata have been
considerably disturbed, and probably only a small proportion of the
field will prove to be productive.
Practically all the available information concerning these Texas
Cretaceous coal fields is contained in a report by T. WaylandVaughan,
entitled Reconnaissance in the Rio Grande coal fields of Texas: Bull.
IT. S. Geol. Survey No. 164, 1900.
Tertiary coalfields. — The Tertiaiy formations in various parts of
the United States contain a large amount of vegetable organic matter
which, in many places, forms beds of lignite. In a few places near
the Pacific coast conditions have been favorable for the conversion of
this lignite into true coal. The most important deposits of this Ter-
tiary coal are in Washington. Here the folding of the inclosing
strata and the intrusion of igneous rocks have converted the lignite
into coal of fair quality. Similar conditions have prevailed at a few
points in the extreme western portion of Oregon and in central and
southern California. The productive fields are all small and have a
total area of about 1,000 square miles. How much of this is produc-
tive has not yet been determined, even approximately, except in a
few of the most thoroughly developed basins. As in the Rocky Moun-
tain Cretaceous fields, the coal beds show great variability in thick-
ness and character, and mining is attended by considerable difficulty,
owing to the disturbed condition of the strata.
In addition to the coal-bearing Tertiary areas of the Pacific coast,
large areas of Tertiary formations occur in the southern portion of
the United States, which contain extensive beds of lignite. These
Tertiary lignites contain a large amount of fuel which will doubtless
some time be utilized. Beginning at the Georgia- Alabama line, a nar-
row belt of lignite-bearing formations extends westward nearly to the
Mississippi River. West of the Mississippi the same formations
occupy a much broader belt, extending from Little Rock southwest-
ward through Arkansas, Louisiana, and Texas. The boundaries of
these areas are quite indefinite, owing to the presence of later deposits,
and probably only a small proportion of the area contains lignite beds
of sufficient thickness and purity to be utilized.
CLASSIFICATION OF THE COAL AS FUEL.
The various fuel requirements call for coals of varying composition,
and the adaptability of any coal to a particular purpose is determined
largely by the relative abundance of the several fuel constituents.
264 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
These consist of the volatile hydrocarbons and of the nonvolatile or
fixed carbon. This relation is expressed by the fuel ratio, a quantity
obtained by dividing the percentage of fixed carbon by the percentage
of the volatile combustible constituents of the coal. In general the
fuel value or heating power increases with the increase of the fuel
ratio, since more heat is developed in the combustion of carbon than
of the hydrocarbon compounds. This increase in fuel value, how-
ever, continues only to a certain point, beyond which the difficulty of
effecting combustion more than makes up for the greater amount of
heat evolved. Thus the graphitic anthracite of the Rhode Island
field can not properly be regarded as a fuel, since the percentage of
volatile constituents is so small that these have to be supplied by. the
addition of another coal before it will burn.
In addition to its fuel constituents, a coal contains others which are
nonessential. The most important of these are water and ash. The
former not only replaces an equal weight of combustible matter but
also absorbs heat in its volatilization. An excessive amount of water,
therefore, detracts seriously from the fuel value of a coal. Its pres-
ence is further detrimental in causing the coal to break up into fine
particles as it dries out. The amount of water generally varies
inversely as the fuel ratio, being less than 1 per cent in some anthra-
cites and from 15 to 25 per cent in lignites.
The ash simply occupies the place of combustible matter and is in
general purely negative in its influence on the fuel. When very
abundant it may seriously retard combustion, and Avhen it contains
easily fusible constituents it may become a positive detriment by
forming clinker on the grate bars. Sulphur is detrimental in a steam-
ing fuel chiefly by reason of the corrosive effect that its products of
combustion exert on iron surfaces with which they come in contact.
For most metallurgical purposes it is essential that the coal should
be relatively free from certain injurious constituents, such as sulphur
and phosphorus.
The amounts of water and ash which a coal contains are not shown
by its fuel ratio, and hence this does not serve to indicate its fuel value
so much as its adaptability for specific purposes. Thus it is evident
that for gas-producing purposes a coal should be chosen having a
large proportion of volatile constituents; in other words, a Ioav fuel
ratio.
The coking quality of a coal depends on conditions which are in
a measure independent of its chemical composition, although coking
coals do not have a very wide range in fuel ratios, which generally
fall between 1. 20 and 2. 50. By no means all coals will coke, however,
whose ratios fall between these limits.
The coal of the Carboniferous fields considered as a whole show a
decrease in their fuel ratios from east to west. In the Rhode Island
field the coal has suffered so high a degree of metamorphism that it
hayes.1 COAL FIELDS OF THE UNITED STATES. 265
has passed the anthracite stage and has been partially converted into
graphite, practically all the volatile compounds having been driven
off. The Pennsylvania anthracite has fuel ratios varying within
rather wide limits. In the analyses accompanying Mr. Stoek's paper a
the maximum is 27 and the minimum 5.11, though most of the samples
analyzed fall between 9 and 22, the average of 10 analyses being 14.11.
Within a narrow belt along the eastern margin of the northern
Appalachian field the coal is relatively hard and high in carbon, form-
ing an intermediate variety between the true anthracite on the east
and the true bituminous on the west. The fuel ratios within this belt
are generally between 3 and 5.
In the greater part of the Appalachian field the coals have fuel ratios
ranging from 1 to 3, and as a rule the ratios are higher in the north-
ern and eastern portions of the field as compared with the southern
and western portions. There are, however, many exceptions to this
rule.
The field presents certain well-marked types of coal which for par-
ticular purposes are regarded as the standard fuels. Thus the coal of
the Pittsburg bed, in the Connellsville district, is usually taken as
the standard with which other coking coals are compared. In the
same way the Pocahontas coal may be considered a standard steam-
ing fuel. Small areas occur in this field containing special varieties
of coal, such as splint, cannel, block, etc. , which are particularly well
suited for certain purposes — as gas-making, domestic, and locomotive
fuel.
The Northern Interior field contains only bituminous coal, which
forms a fair steaming fuel, though it is inferior to most of the Appa-
lachian coals. It generally contains a high percentage of ash and
sulphur. Its fuel ratios vary from about 1.13 to 1.63, the average
of 8 representative analyses given in Dr. Lane's paper6 being 1.40.
Three varieties of coal occur in the Eastern Interior field. By far
the largest part of the coal mined is soft bituminous, making a good
steam fuel. In a belt along the eastern margins of the field in Indiana
is a variety known as block coal, which differs from the ordinary
bituminous in its physical characteristics rather than in chemical
composition. It is especially well adapted for domestic fuel. In the
Kentucky portion of the field are numerous small areas of cannel coal,
particularly valuable for gas making and domestic purposes. The
means of the fuel ratios obtained from a large number are as follows:
For Indiana coals, 1.30; Kentucky, 1.57, and Illinois, 1.71.
The coal of the Western Interior field is fairly uniform in compo-
sition, having an average fuel ratio of about 1.30 and forming a fair
steaming fuel. In the Southwestern field considerable more diversity
is found, the coal varying from soft bituminous, with a fuel ratio of
a Twenty-second Ann. Rept. U. S. Ueol. Survey, Pt. Ill, p. 73. &Ibid., p. 81)7.
266
CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
1.14 in northern Texas, to a semianthracite in Arkansas, with a fuel
ratio of nearly 9. The range in character of the coals in this field is
shown in the accompanying table :
Table showing fuel ratio* of coals in flic Southwestern field.
Arkansas:
Semianthracite
Seinibituminous
Bituminous
Indian Territory :
Bituminous .
North Texas:
Bituminous
Number of
analyses.
27
24
7
Minimum
fuel ratio.
5. 04
3. 51
1 . 26
1.11
Maximum ' Mean fuel
fuel ratio. ratio.
8.96
7.62
4.99
5. 22
5. 79
2. 68
1.45
The Atlantic coasl Triassic <•< >al closely resembles the Carboniferous
coals of the Appalachian field, but is generally higher in ash and
sulphur. In the Richmond area the fuel ratios range from 1.8 to 3.4,
the average of "analyses given by Mr. Woodworth being 2.4.° In the
Deej) River area they range from 1.6 to 3, the average of 17 analyses
being 2.11.
In the Rocky Mountain and Pacific fields the coal presents very
great diversity in character, the same basin sometimes containing all
the intermediate varieties between Lignite, with a fuel ratio less than
1, and anthracite with a ratio of 20 or more. These abrupt changes
in chemical composition and physical properties are due to the vary-
ing degrees of alteration which the coal lias undergone. The altera-
tion is produced by the pressure due to the weight of overlying strata
or to the folding of the strata by mountain-building forces and by the
metamorphism of intrusive igneous rocks. The first of these agen-
cies, vertical pressure, is least effective, but most widespread in its
effects; the second, lateral pressure, is more effective and relatively
local, while the third, intrusion, produces effects which are extremely
localized and correspondingly intense. As a result of these condi-
tions the coal of the plains region is largely lignite, although the
lowest beds, those which have been most deeply buried, approach
most nearly to true coal. Along the flanks of the mountains and in
the interior basins, where the inclosing strata have been moderately
folded, the coal is chiefly bituminous. In the same regions more
intense folding and the intrusion of igneous rocks have converted the
bituminous coal into seinibituminous or anthracite.
"Twenty-second Ann. Rept. U. S. Geol. Survey, Pt. Ill, p. 37.
Lyes.] COAL FIELDS OF THE UNITED STATES. 267
DEVELOPMENT, PRODUCTION, AND MARKETS.
The first development of the several coal fields of the United States
las been in response to the fuel demands of adjoining regions, while
m abundant fuel supply has determined the location of many indus-
trial establishments, which have in turn greatly increased the demand.
The tonnage of coal produced in the various coal fields, as shown in
the table on p. 257, is not proportional to their area, but depends on
other conditions, such as transportation facilities, extent of markets,
and character of the fuel. The largest output in proportion to area
|is in the Pennsylvania anthracite field, where 118,528 tons were pro-
duced in 1800 for each square mile of productive area. This large
output is due to the superiority of anthracite as a domestic and loco-
motive fuel and the density of the population in regions adjacent to
this field. The distribution of the anthracite product to the various
States and the extent to which it competes with the product of other
fields are shown in Mr. Stoek's paper. a
Owing to its location and the excellent character of its coal, the
Northern Appalachian field controls the market for bituminous coal
in the Eastern States, coming in competition in the northeastern por-
tion of this territory only with the Nova Scotian field. It is the near-
est of the large bituminous fields to the seaboard, and will therefore
supply a large proportion of the coal which must be mined to meet
the growing demands of the export trade. Its coal reaches the sea-
ports between New York and Norfolk by a number of direct railroad
lines, the most important of which are the Pennsylvania, Baltimore
and Ohio, Chesapeake and Ohio, and Norfolk and Western.
The Southern Appalachian field supplies the South Atlantic and
Gulf States as far west as the Mississippi. Its southern portion is
almost as near the seaboard as the Northern Appalachian field, and it
will in time support a large export trade, particularly to Central and
South American ports, and on the completion of an isthmian canal to
Pacific coast ports also.
Appalachian coal has an outlet to the West by way of the Great
Lakes, the Ohio River, and numerous trunk-line railroads. Lake
transportation is interrupted in winter, but during the summer season
the Northern Appalachian field supplies most of the markets on the
Great Lakes, competing with the nearer Northern and Eastern Interior
fields. By means of the Ohio River the Northern Appalachian field
supplies adjacent portions of Ohio, Kentucky, and Indiana, as well
as markets along the Lower Mississippi, where it competes with the
Southern Appalachian field.
The markets for the coal of the Northern Interior field are chiefly
within the field itself and in the immediately adjoining region. A
"Twenty-second Ann. Rept. U. S. Geol. Survey, Pt. Ill, p. L03.
268 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
small amount finds a market in the northern peninsula of Michigan
and in Wisconsin. The coal of this field is inferior to that of Penn-
sylvania and Ohio, and can compete with the latter only when it has
a decided advantage in the matter of freights.
The markets of the Eastern Interior field are also chiefly within its
own limits and in immediately adjacent regions. It supplies the
Chicago market in part and also some territory to the northwest and
southwest. It occupies a central position among the Carboniferous
coal fields, and its product comes in competition with that from all
the others. It supplies the markets westward to the margin of the
Western Interior field, but goes eastward only a short distance into
the region which separates it from the Appalachian field, where it
competes not only with the better coal from the latter field, but also
with the cheap fuel supplied by the natural gas fields of Ohio, Indiana,
and Kentucky.
The Western Interior field supplies the markets within its own
borders and toward the north and west, where it comes in competi-
tion with the Rocky Mountain fields.
The Southwestern field supplies the markets in a large territory
toward the south and west, in which it had little competition until the
development of the California and Texas oil fields made liquid fuel
available. Practically all the coal used by the Southern transconti-
nental railroads, as well as the Texas roads, comes from the north
Texas and Indian Territory fields. The hard coals of the Arkansas
field supply an extensive region west of the Mississippi River with
a high-grade domestic fuel, which bears a relation to the neighbor-
ing soft coals somewhat similar to that borne by the Pennsylvania
anthracite to the Appalachian bituminous coals.
Considering the entire region between the Appalachian coal field
and the Rocky Mountain fields, there is observed a general westward
movement of the coal. Thus the product of the Western Interior
field goes west almost exclusively, that of the Eastern Interior field
goes west to and within the borders of the Western Interior field,
while the Appalachian coal goes west across both the Eastern and
Western Interior fields and beyond the territory of the latter, com-
peting with the Rocky Mountain coals to some extent. This west-
ward tendency is due chiefly to the higher grade of the Eastern coals,
but in part also to the fact that railroad freight rates are generally
lower westward than eastward; water transportation also favors the
westward rather than the eastward movement of coal.
The region west of the one hundredth meridian, which constitutes
about half the area of the United States exclusive of Alaska and the
other outlying possessions, contains less than 20 per cent of the coal
fields. The largest area entirely without coal lies between the Rocky
Mountains and the Pacific coast. This, however, is a region in which
hayes.] COAL FIELDS OF THE UNITED STATES. 269
tin* population is scanty and the fuel requirements are consequently
small. The Pacific coast markets are supplied chiefly by the Wash-
ington fields, though considerable coal comes from the Nanaimo dis-
trict in British Columbia, and some also from England as ballast in
grain vessels, and from Australia as a return cargo.
The development of the coal resources of Alaska is as yet in the
experimental stage. A local fuel supply is of the greatest importance
to this territory, and the present indications are that such a supply
will be furnished by some of the fields now known or others not yet
discovered. a
a Practically all the information at present available concerning these Alaskan coal fields was
summarized by Mr Brooks in the Twenty-second Ann. Rept. U. S. Geol. Survey, Pt. Ill, pp.
521-569.
RECENT WORK IN THE BITUMINOUS COAL FIELD OF
PENNSYLVANIA.
By M. R. Campbell.
INTRODUCTION.
%
During the past three years the United States Geological Survey, in
cooperation with the State, has been engaged in a geologic survey of
the bituminous coal field of Pennsvlvania. The region is one in
which considerable geologic work has already been done, and con-
sequently particular attention has been paid to those features which
had received least attention in the previous work.
In this region the feature of greatest economic importance is coal,
but petroleum, natural gas, and clay have each come to be recog-
nized as second in value only to the great coal beds which have made
this part of the State famous. Inasmuch as the accumulations of
oil and gas are directly influenced by the geologic structure of the
region, and since the economical mining of coal and clay also depends
upon the same element, it was decided to give most attention to the
working out in detail of the form and dimensions of the folds which
traverse the strata in the bituminous coal field. As is well known,
the rocks of the northern end of this field are crumpled into long, nar-
row folds which traverse t he basin along lines rudely parallel with the
Allegheny front and gradually decrease in magnitude from east to
west and also from the point of the basin tow7ard its center in the
southwestern corner of the State. Although these facts have long been
understood, the exact form and irregularities of these folds have never
been accurately determined.
Since the geologic structure is based upon very accurate contour
maps, in which the vertical element is generally ascertained with a
spirit level, the determination of the attitude of the beds is a com-
paratively easy matter. Some particularly prominent bed was selected
as the reference stratum, and its altitude was determined at a great
many points. From these collected data contours of equal elevation
were drawn upon the surface of the stratum so selected, and by this
means the size and shape of the folds are made manifest.
Aside from this structure work, the outcrops of the coal were care-
fully studied and correlated, and they are represented on the geologic
maps by means of heavy lines, which show the extent of their known
outcrops and the position which they occupy in the hillsides.
270
camibkll] BITUMINOUS COAL FIELD OF PENNSYLVANIA. 27 1
MONONGAHELA VALLEY.
Up to the present time six 15-minute quadrangles have been sur-
veyed in the southwestern part of the State, where the great Pittsburg
coal bed outcrops. In this territory coal is by far the most important
economic factor. The area so far snrvej^ed covers nearly the whole
of the celebrated Connellsville coke field, a portion of the gas coal
field of the Irwin or Port Royal basin, and much of the territory
along Monongahela and Youghiogheny rivers, in which the coal is
mined for fuel only. The determination of the geologic structure in
this field is of the utmost importance to coal operators, for their mines
must be developed in accordance with it, and for this purpose alone
the representation of the structure by means of contour lines is worth
many times the cost of the work.
In this part of the field there are a number of coals higher in the
series than the great Pittsburg bed, but they are not utilized at
present, and presumably the}7 will not be until the great coal bed
beneath them is exhausted. Of these coals the more important are the
Redstone, lying from 50 to 80 feet above the Pittsburg; the Sewickley,
at about 120 feet, and the Waynesburg coal, at from 330 to 400 feet.
The last-mentioned coal is the thickest bed above the Pittsburg hori-
zon, but it is generally so full of impurities that its value is not so
great as that of some of the smaller beds.
Below the Pittsburg coal there are several beds of coal in the Alle-
gheny measures, but they probably will not be utilized until the
better coal is exhausted. The most important of these beds is the
Upper Freerjort, which lies at the top of the Allegheny formation.
Along the west foot of Chestnut Ridge this bed attains a great aggre-
gate thickness, but it is so badly broken by shale partings that it is
expensive to mine, and the fuel when mined is of inferior quality.
Associated witli the coal beds of the Allegheny formation are some
valuable deposits of fire clay, which are being worked to some extent
along the Youghiogheny River and on Chestnut Ridge. These clays
are highly refractory and of great importance in the coke regions,
where the consumption of fire brick in the building of ovens is
enormous.
The territory surveyed in Monongahela Vallej7 includes two or three
prominent gas fields and a few very small pools of oil. The largest
gas fields are located along the crest of the Bellevernon or Waynes-
burg anticline. They have two points of development — one near
Waynesburg, in Greene County, and the other where 1 he axis crosses
the Monongahela River near Bellevernon. A small but very produc-
tive field has lately been developed upon the Fayette anticline in
Fayette County, just west of Uniontown. These gas fields a re usually
found upon the crests of the anticlines, and it is possible that they
may be extended along the axial lines. The highest point of the Fay-
ette anticline, near Jacobs Creek, has never been tested by the drill,
272 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. ^13.
and it is possible that a new field may be developed at this point.
From a structural standpoint it seems to be a verj^ promising field,
and it is to be hoped that before long the drill will be put down in
this region.
The quadrangles surveyed in this part of the field are the Union-
town, Masontown, Brownsville, Connellsville, Latrobe, and Waynes-
burg. The work on the first two quadrangles has been completed,
and the results are published in the Masontown-Uniontown folio.
The Brownsville and Connellsville will likewise be published together,
and will soon be ready for distribution. The reports on the Waynes-
burg and Latrobe have not yet been submitted, and it will be some
time before they are published.
ALLEGHENY VALLEY.
Regular areal surveys have also been carried on in the Allegheny
Valley and in territory adjacent on the east. This includes the Kit-
tanning, Rural Valley, Eldersridge, and Indiana quadrangles, and is
located mainly in Armstrong and Indiana counties, but includes also
a narrow strip of the eastern part of Butler County.
So far as the stratigraphy is concerned the work is almost identical
with that of previous surveys. No marked differences occur, except
that in places extensive developments have taken place in late years,
and some of the coal beds may be traced beneath the surface with
much more certainty than was possible at the time of the other sur-
veys of the region. From an economic standpoint the Upper Freeport
and the Lower Kittanning coal beds are the most important strati-
graphic features, and their underlying fire clays are also of great
value. They have a wide distribution over this territory, and they
are worked along the Allegheny River, Redbank and Cowanshannock
creeks, and on the Kiskiminitas River.
The key rocks in this part of the basin are not so good as they are
in the Monongahela Valley, and consequently folds have not been so
definitely located as in the Monongahela Valley. The principal work
of the present survey is the determination of the structure, and the
results are very different from those contained in the published
reports.
The opinion is prevalent among oil men in this region that the pools
of oil bear no definite relation to the geologic structure. As deter-
mined by the second geological survey, the structures in the vicinity
of Bradys Bend trend regularly about 35° E,, while the oil pools gen-
erally extend either in an east- west direction, or nearly at right angles
to this, in a north-south direction. It is manifest that it is impossible
to harmonize these supposed facts, and consequently it was natural
for the oil men to arrive at their conclusion that the accumulations of
oil bear little or no relation to the geologic structure.
Oil does not occur in the eastern part of the territory, but the prin-
Campbell] BITUMINOUS COAL FIELD OF PENNSYLVANIA. 273
cipal anticlinal folds show some extensive fields of gas. The exten-
sions of these fields are always along the crest of the anticlines, and
the gas men soon found that the folds as previously mapped are incor-
rect. Instead of coming to the conclusion that the gas fields bear no
relation to the structure, they at once satisfied themselves that the
previous determination of the structure was inaccurate.
The areal mapping of the territory shows conclusively that the gas
men are correct in their conclusions, and that when the structure of
the oil field is correctly represented it is entirely in harmony with the
location of the oil pools.
One of the most pronounced changes in the interpretation of this
region is in what was formerly called the Bradys Bend anticline.
This was supposed to cross the river at the mouth of Redbank Creek
and to extend in a straight line along a course about north 35° E.
The present work shows that the location of this anticline near the
Butler County line is correct, but instead of crossing the river at the
mouth of Redbank Creek it swings sharply to the east and crosses
the river just above the mouth of Mahoning Creek, corresponding at
that point with the anticline formerly known as the Kellersburg, and
extending across Redbank Creek on the line formerly supposed to
represent Anthonys Bend anticline. In other words, the anticlines
formerly designated Bradys Bend, Kellersburg, and Anthonys Bend
are all on the same fold. The synclinal basin west of Bradys Bend
anticline shows a corresponding swing to the east and agrees approx-
imately with the Lawsonham syncline, as previously determined.
The abrupt bend in this synclinal basin gives strikes nearly east and
west in the vicinity of Bradys Bend and also nearly north and south
on the Butler County line. This is in perfect agreement with the
trend of the oil pools in this region, and is conclusive proof that when
the structure is well understood it may be used as a guide in extend-
ing oil operations.
The Fairmount syncline was fairly well determined in previous sur-
veys, except that in the vicinity of Mahoning Creek it bifurcates and
the right branch swings to the east along the creek and replaces what
was formerly called the Leechburg syncline. This change has no
direct effect on any economic product, but it shows that the previous
determination of straight axes is very misleading.
The most important change in the eastern part of Armstrong County
is in the anticline which lies next east to the Fairmount syncline. In
previous work this had been broken up and received different names;
along Crooked Creek and Kiskiminitas River it was known as the
Bagdad anticline, while on Pine and Mahoning creeks it was called
Greendale anticline. These two folds are now known to be continuous,
and instead of extending in a straight line to the northeast after
crossing Pine Creek, it swings sharply to the right in harmony with
Bull. 213—03 18
274 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
the right fork of the Fair mount syncline, and at the crossing of Mahon-
ing Creek corresponds with what was formerly known as the Glade
Run anticline. We have, then, instead of the Bagdad, Greendale, and
Glade Run anticlines one continuous fold which will probably receive
the name of the Greendale anticline. This eastward swing of the
anticline between Pine and Mahoning creeks had been determined by
the gas men previous to the present survey, but it had never been
mapped, and consequently its position is not generally known.
The data concerning the great synclinal basin east of the Greendale
anticline have not yet been worked up, and consequently it is impos-
sible to say what are the details of structure in this broad basin.
In the southern part of Armstrong and Indiana counties, errors
have been found in the former determination of the position of the
axes. Heretofore the Roaring Run anticline was not supposed to
extend to the north much beyond the crossing of Crooked Creek. In
the course of the present work this fold was found to cross Crooked
Creek and then swing sharply to the east and to enter Indiana County
along the South Fork of Plum Creek.
One of the most pronounced errors in the previous determinations
of the structure of this region occurs in Indiana County, where numer-
ous diamond-drill holes show that there is a pronounced syncline
through the town of Indiana, where formerly an anticline was supposed
to exist." The first anticline west of Chestnut Ridge is one of the
most pronounced folds of the region. It has been traced continuously
from the AVest Virginia line to Coneinaugh River, and in previous
reports it was extended across Indiana County, and was given the
name of the Indiana anticline. This name has been extensively used
by several writers, and is in current use to-day to designate the long
anticlinal fold previously described. The present work has demon-
strated clearly that this anticlinal fold dies out near the Conemaugh
River, and the two synclinal basins on either side coalesce and extend
beyond the town of Indiana along a continuation of the same line
that the anticline follows farther south.
The direct results obtained during the course of this survey in the
Allegheny Valley are regarded as the most important contribution to
the economic geology of the coal field that has appeared during the
present decade. When rightly understood they are of the greatest
importance to oil and gas men and of nearly equal value to coal
operators.
The amount of data required for such work is enormous, and con-
sequently the work of office preparation is necessarily slow. The
maps of the Indiana folio are now being engraved, and before many
months they will be ready for distribution. The reports on the other
quadrangles are not so far advanced, but will be published as soon as
it is possible to assemble the data and engrave the maps and print
them.
"Richardson, G. B., The misnamed Indiana anticline: Jour. Geol., Vol. X, pp. 700-702.
campbell.] BITUMINOUS COAL FIELD OF PENNSYLVANIA. 275
BEAVER VALLEY.
Only a small territory has been surveyed in Beaver Valley. This
territory is included in the Beaver quadrangle, which lies mainly in
Beaver County. The structure and stratigraphie results differ very
little from those obtained in previous surveys. The principal point
of improvement is in the excellent topographic map upon which the
material will be shown and in the great detail with which the stratig-
raphy was worked. The Upper Freeport and Lower Kittanning coal
beds are the principal sources of fuel in this region, but the most
valuable deposits are probably the fire clays which are associated
with the Kittanning group of coals. These are widely developed
geographically and have been worked for a great many years. They
have given the region prominence in the manufacture of clay pro-
ducts, but not all of the raw material has been derived from the local
beds. Some oil and gas occurs in this region, but the fields are not
large and the wells are generally small producers.
COAL RESOURCES OF THE YUKON BASIN, ALASKA."
By Arthur J. Collier.
INTRODUCTION.
The coal beds of the Alaskan part of the Yukon Basin occur in soft
sandstones and shales, with intercalated beds of conglomerate. These
beds are in part in the Nulato series of the Upper Cretaceous and
in part in the Kenai series of the Eocene. The two series are appar-
ently conformable and have strikingly similar lithologic characters.
They can be separated only after close stral [graphic and paleontologie
study, and hence it is not now possible to state definitely what part
of the coals are Cretaceous and what part are Eocene
For the purpose of discussing its coal resources the Yukon Basin of
Alaska may be divided into three provinces. The Upper Yukon
includes that part of the valley lying between the international
boundary and the great lowland known as the Yukon Flats. The
Middle Yukon includes that part of the valley lying between the
Yukon Flats and the mouth of the Tanana, and the Lower Yukon the
portion of the valley from the mouth of the Tanana to the sea. In
the Upper and Middle Yukon provinces the coal-bearing rocks occur
in small basins surrounded by older rocks. The sandstones of these
basins, as far as determined, belong to the Kenai series, and are cor-
related with the coal-bearing beds of southern Alaska. With a single
exception these coals are either high-grade lignites or lignitic bitumi-
nous coals. h
The coal-bearing beds of the Lower Yukon are exposed continu-
ously for 200 miles along the river, and they probably extend west-
ward to include the area which has been reported near Norton Sound.
This terrane is made up of sandstones, shales, and conglomerates,
which probably form an uninterrupted sedimentary series, ranging in
age from the Middle Cretaceous to the Upper Eocene, and hence
including both the Nulato and the Kenai series. Both these series
carry coals of economic importance in this province, practically all of
which are of a bituminous character.
In the following pages the localities will be described according to
"Abstract of paper in preparation.
& A coal whose content of water is above 10 per cent and whose fuel ratio is less than 1 is
regarded as a lignite. The fuel ratio is the quotient of the fixed carbon divided by the volatile
combustible matter. Coals whose classification by this rule is in doubt have been called lignitic
bituminous coals.
276
collier.] COAL KESOURCES OF THE YUKON BASIN. 277
their geographic position, beginning at the international boundary
and going down the river.
UPPER YUKON PROVINCE.
Mission Creek and Seventymile River. — A small basin of coal-bearing
rocks, 7 or 8 miles in width, lies near Mission Creek, 12 miles below
the international boundary. The beds are of Kenai age and the coals
are probably lignites. Twenty-five miles below, on Seventymile
River, is another small basin of Kenai rocks from which coal has been
reported, but nothing of economic importance has as yet been devel-
oped at either of these localities.
Washington Creek. — On Washington Creek, which enters the Yukon
from the south, about 82 miles below the international boundary, there
is a large area of coal-bearing rocks which is probably a part of a long
basin or series of basins lying south of the Yukon and including the
coal-bearing formations on Seventymile River, Bonanza Creek, and
Coal Creek. No fossils were obtained in the Washington Creek coal
basin, but an Upper Eocene age is inferred from the lithologic character
of the sandstone, the mode of occurrence of the coal beds, and the
character of the coal. In all these respects this coal basin resembles
that at Cliff Creek, in Canadian territory, from which Eocene fossils
were obtained. The coal here occurs in a formation consisting of alter-
nating beds of lignite, clay, and carbonaceous shale, resembling that
at Cliff Creek. In this formation seams of clear coal above 5 feet in
thickness occur. The coal is a high-grade lignite, having an average
fuel ratio of about 1 and a water content of from 10 to 15 per cent.
The ash in samples analyzed varies from 2 to 4 per cent, and the sul-
phur is less than three-tenths of 1 per cent. Wherever they have
been opened the coal beds of the Washington Creek Basin show no
evidence of faulting, and the coal is not crushed, but can be obtained
in large pieces which "check" but do not break up readily on expo-
sure to the air. Coal beds have been opened in this basin at localities
several miles apart, showing that they have considerable extent.
Where these beds have been prospected the dips vary from 35° to 45°.
The relief of the basin is low, and probably the greater part of the
coal lies below drainage level, so that pumping will be necessary if
the mines are worked.
This coal has not been mined on a commercial scale. The develop-
ment in evidence consists of a tunnel 65 feet long and a slope 106 feet
long. Other workings were of a temporary nature and have caved
in. A good winter trail has been opened from the coal beds to the
Yukon River, and last winter 5 tons of coal were sledded to the Yukon
for a steam test on a river steamer. This is reported to have given
entire satisfaction. A railroad 10 to 12 miles in length will be required
to bring this coal to the Yukon.
Bonanza and Coal creeks. — A similar basin is reported on Bonanza
278 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
Creek, a tributary of Charley River, about 10 miles northwest of the
Washington Creek Basin.
Coal Creek, about 11 miles below Charley River, has coal of a sim-
ilar character. These deposits are about 6 miles from the Yukon,
and they have not yet been successfully exploited.
Nation River mine. — The localities thus far described all lie on the
south side of the Yukon and seem to belong to a series of Kenai
basins which extends from the Klondike River, in Canadian terri-
tory, northwest to Coal Creek, in American territory, a distance of
about 160 miles.
On the north side of the Yukon, 52 miles below the international
boundary, coal outcrops, and has been mined to some extent on Tah-
kandit or Nation River, 1^ miles from the Yukon. The coal-bearing
formation extends down the Yukon for several miles and is generally
more intensely folded than the sandstones above described. From
the evidence in hand it may be regarded either as Permian or a later
formation, presumably Kenai, infolded with Permian rocks.
The coal is distinctly bituminous, having a fuel ratio of 1.39 and a
water content of 1.39 per cent. The ash percentage is 3.04, while the
percentage of sulphur is very high as compared with other Yukon
coal, being 2.98 per cent. This coal shows no vestige of woody struc-
ture and in the laboratory makes a good coke. The coal has been
intensely crushed and affected, probably by a shearing movement of
the inclosing sandstone, so that the bed is not well defined, but the
coal was found in lenses and kidneys often as large as 8 feet thick
and 13 feet long.
In 1897 the Alaska Commercial Company attempted to open a coal
mine at this place. About 2,000 tons" of coal were mined and sledded
to a landing on the Yukon River. Owing to the irregularity of the
bed and the consequent uncertainty of the suppl}7 and expense of
mining it was abandoned several years ago.
MIDDLE YUKON PROVINCE.
Between the Upper Yukon and Middle Yukon provinces, along the
river, there is a break of about 300 miles in which there are no coal
beds known.
Dall River. — On Dall River, which enters the Yukon from the north
side, at the lower end of the Yukon Flats and about 450 miles below
the international boundary, a coal bed occurs, 70 miles from the Yukon,
in shales which are supposed to belong to the Kenai series. This coal
bed contains irregular streaks of clay, but the lower 4 or 5 feet of the
seam are believed to be of good quality. No practical tests and no
analyses of the coal have been made. b
a For estimates of the amounts of coal produced the writer is indebted to Mr. W. E. Williams,
a mining engineer who has had charge of coal mines on the Yukon since 1897.
&Mendenhall, W. C, Reconnaissance from Fort Hamlin to Kotzebue Sound: Professional Paper
U. S. Geol. Survey No. 10, 1902.
collier.] COAL EESOURCES OF THE YUKON BASIN. 279
Salt Creek. — Coal is also reported by prospectors to occur on Salt
Creek, which enters the Yukon from the north, 2-5 miles below Dall
River.
Drew mine. — The Drew mine is the only point at which coal has
actually been mined in this province. It is on the right bank of the
Yukon opposite the mouth of Hess Creek, 25 miles above Rampart
and about 500 miles below the international boundary. Its position
is an important one, since there are no valuable coal deposits known
along the Yukon, either above or below it, within 200 miles. The coal-
bearing formation exposed here is confined to a great bend of the
Yukon River, and its known extent does not exceed 4 square miles,
though it may be continued beneath the silts of the Yukon and Hess
Creek. The coal-bearing formation here consists of a great thick-
ness— probably over 5,000 feet — of soft sandstones, shales, and con-
glomerates of Kenai age, standing nearly vertical and striking at right
angles with the course of the river.
From croppings seen along the river bank, it is believed that there
are seven seams of coal contained in about 1,000 feet of soft sand-
stone and shale of the upper part of the series, but only one has been
exploited. Within the mine this bed was found to consist of two
seams of clean coal in about 19 feet of coaly shale. These seams
measured 13 and 25 inches and were separated by 4 feet of bony coal
and black shale. The analyses show that the coal from the two
seams is lignitic and quite similar in quality, having fuel ratios
between 0.93 and 1.08, and a water content above 9.5 per cent. Both
samples show over 13 per cent ash. A sample taken from the crop-
pings of one of the other veins which has been partially opened up
had a fuel ratio of 0.72 and a water content of 14.44 per cent, but the
percentage of ash is only 4.04.
The development in this mine includes a shaft 75 feet deep, from
the foot of which a crosscut tunnel about 30 feet long reaches the
coal bed. The shaft is cribbed and housed and equipped with steam
hoisting gear. A bunker of about 80 tons capacity is conveniently
located on the river bank, from which the coal can be loaded on
steamers. About 1,200 tons of coal have been mined here, the greater
part of which was used for steaming purposes on river boats, but
did not give entire satisfaction. This dissatisfaction was due in part,
no doubt, to the inexperience of the firemen and the unsuitable
grates used. The coal was carelessly mined so that, as supplied at
the bunkers, it contained more or less unnecessary dirt, but in spite
of this it sold readily for $15 per ton while the mine was in operation.
For the past two years the mine has been shut down under an attach-
ment suit instituted by the Northern Commercial Company.
Minook Creek. — A series of sandstones, probably of Kenai age, out-
crops along the Yukon in the vicinity of Minook Creek, and also
280 CONTRIBUTIONS TO ECONOMIC GEOLOGY. 1902. [bull 213
extends up the valley of that stream. Attempts at coal mining havt
been made on Minook Creek, near the mouth of Hunter Creek, but the
workings have been abandoned and have since caved in, so that the
thickness of the bed could not be determined. A sample taken from
the dump of the old prospect shows the coal to be a glossy lignite,
which tends to break up into small cubical grains on drying. The f
analysis shows a fuel ratio of 0.87 and a water content of 11.21 per
cent. Probably in freshly mined coal the water content would be
much higher.
Below Rampart. — A similar coal outcrops 2 miles below Rampart
on the left bank of the Yukon. A sample from the dump of an old
prospect showed upon analysis a fuel ratio of 0.86 and a water con-
tent of 16.43 per cent. Between Rampart and the mouth of the Tan-
ana two large areas of Kenai sandstone occur which have been
reported to carry beds of coal, but so far as is known to the writer they
have no commercial importance.
Cantwell River. — On the Cantwell River, which is a southern tribu-
tary of theTanana River, about 100 miles from its junction with the
Yukon, Brooks reports a great thickness of lignite-bearing sandstones
believed to be Eocene. At one locality about 50 to 60 feet of lignite is
contained in fifteen different seams. The analyses of this fuel shows
that it has a fuel ratio of 0.66 and a water content of 13.03 per cent.
LOWER YUKON PROVINCE
Palisades. — At the Palisades, a series of silt cliffs about 55 miles
below Tanana, a number of beds of lignite are exposed in the face of
1 he cliff. This lignite is of Pleistocene or late Tertiary age and occurs
in beds often several feet in thickness. It is of inferior quality, being
but little changed from wood or peat, and lias no economic value.
Nohatatiltin. — The Nohatatiltin coal bed is situated on the right
bank of the Yukon 55 miles above Nulato and about 760 miles below
the international boundary. It is in sandstones containing fossils of
Eocene age, which probably overlie conformably Upper Cretaceous
rocks of the Nulato formation. Two beds of coal were examined and
two others are reported to have been opened by prospectors. Owing
to the disturbed condition of the sandstone it is not certain that these
may not all be parts of one faulted bed. The largest bed seen has a
thickness of 1 foot and is not. of commercial importance. The coal
is a low-grade bituminous, having a fuel ratio 1.17 and a water con-
tent 6.88 per cent.
Pichart mine. — This mine is 10 miles above Nulato, on the right bank
of the Yukon, and 425 miles from its mouth. The coal bed is con-
tained in a typical exposure of the Nulato sandstone, from which
Upper Cretaceous fossils have been obtained. One coal bed 30 inches
thick and having a dip of 35° has been exploited. The coal is bitu-
T
f
v
aj collier.] COAL RESOUKCES OF THE YUKON BASIN. 281
urinous, having a fuel ratio of 2.38 and a water content of 1.03 per
lie cent. In the laboratory it makes a compact coke.
Mining was begun at this place in 1898- by the Pickart Brothers.
About two years ago the mine passed into the hands of the Alaska
Commercial Company, and in the summer of 1902 it was abandoned on
account of some " rolls" in the floor of the bed which cut off the coal.
The development consists of a drift tunnel about 600 feet long, above
which all the available coal has been mined. No bunkers were used.
The coal was piled on the river beach at the mouth of the mine and
loaded on steamers by means of wheelbarrows.
Nulato coal bed. — About 1 mile above Nulato, a prospect hole shows
2^ feet of bony coal, with several bands of clay, in the Nulato sand-
stone. This seam contains 6 inches of clean coal, which is used to a
limited extent for blacksmithing at Nulato.
Bush mine. — This mine is located on the right bank of the
Yukon, 4 miles below Nulato. The inclosing rock is Nulato sand-
stone. The development is not far enough advanced to show the
nature of the coal bed. In the tunnel, which extends about 40 feet,
large bodies of crushed coal 4 or 5 feet in thickness are exposed.
The coal is regarded as bituminous, having a fuel ratio of 1.76 and a
water content of 11.17 per cent. The high percentage of water is
probably due to decomposition of the coal in the croppings. No coal
has been produced, but the owners have contracted to deliver 400
tons before next summer.
Blatchford a mine. — This mine is located 9 miles below Nulato.
The coal bed occurs in sandstone, probably of Upper Cretaceous age,
which has been correlated with the Nulato sandstone. One workable
coal bed has been opened at this place. This bed has been crushed
and sheared by the movements of the inclosing strata, making it very
irregular. Large masses, 8 feet in diameter, have been found and
mined out, showing that before it was disturbed the coal bed probably
had considerable thickness. The coal has a tendency to break up
into fine pieces, though it is a bituminous coal, having a fuel ratio of
3.30, the highest of any coal on the Yukon, and a water content of
1.36 per cent. The ash is only 2.22 per cent, making it by proximate
analysis the best coal seen by the writer on the Yukon River. This
mine has no visible development or permanent equipment. The
workings lie below the level of the river, and the entrance is covered
with water during the summer months, so that it can be worked only
in winter after the freezing up of the river, when the ice filling the
upper workings must be mined out before the coal can be reached.
The mine has probably produced about 300 tons of coal.
Williams mine. — This mine is located on the right bank of the
"This name is also written Blatsford. The correct spelling is in <!<>ul>t .
282 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
p.!
Yukon, about 90 miles below Nulato. The coal is in sandstones, from
which fossils of Eocene age have been collected.
One bed 39 inches in thickness, in two nearly equal benches, sepa-
rated by a clay parting about 1 inch thick, has been opened. The
bed, which has a dip of 45°, is very regular and shows no variation,
either in strike or thickness, in a distance of 400 feet. The coal is |
bituminous, having a fuel ratio between 1.20 and 1.50 and water con
tent between 6 and 7 per cent. The ash in the lower bench is 3.53 per ]
cent and in the upper bench 8.63 per cent. The coal does not coke.
This mine produced some coal as early as 1900, and early in 1902 it
passed into the hands of the present owners. The equipment consists
of a drift 400 feet long, starting from the river bank above high water.
The greater part of the coal above this drift has been mined. The
coal cars bring the fuel to the mouth of the mine, where it is piled on
the river beach and loaded on steamers by means of wheelbarrows.
One thousand seven hundred tons 'of coal, which sold at the mine for
from $10 to $15 per ton, have been produced.
Coal mine No. 1. — This mine is on the right bank of the Yukon, 25
miles below the Williams mine. The coal is contained in sandstones,
which may be either Upper Cretaceous or Eocene in age. One coal bed,
having a thickness of from 2^ to 3 feet, has been mined. A sample
of the coal taken from the cropping shows on analysis that the coal is
bituminous, with a fuel ratio of 1.61 and a water content 4.82 per cent.
The Alaska Commercial Company attempted in the winter of 1898 to
open a mine here, and 900 tons of coal were taken out, but the mine
was abandoned the same year on account of the difficult}' encountered
in keeping out the water.
Hall Rapids. — Near Hall Rapids, about 30 miles above Anvik, a
small bed of coal'has been found in a formation consisting of white
and yellowish tuft's of undetermined age. This coal has a lignitic
appearance, but on analysis shows a fuel ratio of 1.35 and a water
content of 8.23 per cent. The coal bed is probabl}7 of no value on
account of its limited extent. Similar coals or lignites are of frequent
occurrence in these tuffs.
On the Upper Koyuhuk River. — A coal bed containing 9 feet of com-
paratively pure coal occurs near Tramway Bar.a This coal is either
Upper Cretaceous or Eocene, but the exact age is undetermined. The
analysis shows that it is a bituminous coal, having a fuel ratio of 1.40
and a percentage of moisture of 4.47 per cent.
Anvik River. — On the Anvik River, about 50 miles up, coal is
reported by Mr. J. W. Chapman, missionary at Anvik. The point is
about 10 miles back from the Yukon and probably is in a general way
opposite the Williams mines. The coal is exposed in the river bank
and is used by the natives in making black paint.
aScnrader, F. C, Reconnaissance on Chandlar and Koyukuk rivers: Twenty-first Ann. Rept.
U. S. Geol. Survey, Part II, p. 485.
cor.LiEu.] COAL RESOURCES OF THE YUKON BASIN. 283
SUMMARY.
The coal-bearing formations are distributed along the Yukon con-
veniently for steaming purposes from the international boundary
nearly to the mouth of the river. The coal beds are practically unde-
veloped, though limited amounts of coal have been mined at eight
different points scattered along 1,000 miles of the river. Probably
about 9,000 tons have been produced in American territory, which
have sold at from $10 to $20 per ton. The seams from which coal has
been produced vary in thickness from 13 inches to 5 feet, and in some
instances they have been crushed and broken by movements of the
inclosing strata, so that the beds are very irregular. The coal varies
in quality from lignite to semibituminous. It has been used chiefly
for steaming purposes on river boats and has come into competition
with wood cut along the river. During the summer of 1903 crude oil
from California Avillbe burned on some of the steamers on the Yukon.
Should its use on the Yukon prove practicable, the development of
the coal beds will no doubt be retarded by it.
The Yukon will probably never supply coal for exportation, but the
coal beds at present known seem to be capable, with proper develop-
ment, of furnishing all that will be required for local use.
RECENT WORK IN THE COAL EIELD OF INDIANA AND ILLINOIS.
By Myron L. Fuller and George H. Ashley
INTRODUCTION.
The coal investigations recently conducted by the United States
Geological Survey in the States of Indiana and Illinois were limited to
the southern portions of the two States, the areas covered being
included in two adjacent thirty-minute quadrangles. The easterly
one, known as the Ditney, embraces portions of Pike, Gibson, Van-
derburg, Warrick, Spencer, and Dubois counties of Indiana, and the
westerly quadrangle, known as the Patoka, includes the remaining
parts of Gibson and Vanderburg counties, portions of Posey and Knox
counties in Indiana, and of Wabash, Edwards, and White counties in
Illinois. The combined area of the two quadrangles is 1,872 square
miles.
The investigations in the Ditney quadrangle were prosecuted in
1900 and 1901, and the results have already appeared in the form of
a geologic folio, a in which are given, in addition to the descriptions,
maps showing the outcrops of the geologic formations, contours show-
ing the approximate depth of the principal coal, and a large number
of sections showing the thickness, character, and structural relations
of the coals. The investigations in the Patoka quadrangle were pros-
ecuted in the latter part of 1902, and the results will be prepared and
published in the same form as those relating to the Ditney quadrangle.
COALS OF THE DITNEY QUADRANGLE.
Five or more beds of this quadrangle are of sufficient thickness to
warrant development, at least for local' supplies, but only one of the
beds, the Petersburg coal, is worked for purposes of shipment. The
other veins, however, especially the Millersburg coal, are extensively
mined in the fall and winter months to supply local demands. The
coals vary greatly in thickness at different points, and all of them
show marked and sudden changes, due to their accumulation, it is
believed, in basins of variable depth, or in series of basins that were
only partially connected or even completely separated. The coals
above the Millersburg are few in number, are usually under a foot
in thickness, and, except in rare instances, are not workable even for
local purposes.
« Geologic Atlas U. S., folio 84, Ditney, Ind.
284
ruLLEit and ashlky.] COAL FIELDS OF INDIANA AND ILLINOIS. 285
MILLERSBURG COAL.
Because of the covering of glacial drift and of certain confusing
associations there is not that certainty in the tracing of this bed that
characterizes the tracing of the more prominent Petersburg coal, but
what appears to be a single bed, or at least a bed of a closely equiva-
lent horizon, has been traced in the area under discussion from near
Chandler on the south to Petersburg on the north, the outcrop passing
near Lynville, Oakland City, Ingleton, Dongola, Glezen, Rumble, and
Clark. The outcrop is worked by stoppings at over a hundred points,
the workings being especially numerous along Squaw Creek east of
Millersburg, south of Lynville, north of Ingleton, on both sides of the
Patoka River at Dongola, along Robinson Creek, southeast of Rumble,
and between Rumble and Petersburg. The thickness is generally
insufficient to warrant shafting, but the coal is worked from shallow
shafts at Millersburg, east of Elberfeld, and at Union. A shaft is
now (1902) being sunk to this coal near Buckskin, where the coal is
reported to reach a thickness of over 6 feet.
The thickness of the Millersburg coal varies from 2 to 6 feet or
more, 3 feet probably being a fair average for the area as a whole.
A number of the more characteristic local measurements are given in
the table on page 288.
The interval separating the Millersburg coal from the next lower or
Petersburg bed is generally from 70 to 90 feet, but if the correlations
are correct the interval increases to about 100 feet near Ingleton and
to 120 feet near Oakland City.
PETERSBURG COAL.
The outcrop of the Petersburg coal is largely hidden by glacial
deposits in the northern portion of the quadrangle, but over an area
beginning near Cato and continuing to the southern border, south of
Boonville, it has been opened at many points and is worked at short
intervals. The dip being very gentle, averaging only about 20 feet
to the mile to the west, and the coal lying at or near drainage level
over considerable areas, the outcrop partakes of all the sinuosities of
the drainage lines, its length being several times that of the
quadrangle.
The coal is of variable thickness, but probably averages about 5 feet
in this quadrangle. East and northeast of Boonville, however, its
average thickness is somewhat greater, being not far from 6 feet, and
thicknesses of 7 feet are common in many of the mines, while in
pockets a thickness as high as 9£ feet is reported. In this region it is
solid and uniform throughout, except that the upper 3 to 6 inches is
dry, resembling cannel coal in places. Thicknesses of 8 feet occur in
many of the mines about Petersburg. At other points thicknesses of
4 to 6 feet are most common. Measurements at a large number of
points are given in the table on page 289.
286
OONTKIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
It is believed locally that the coal worked at or near the surface at
Ayrshire and between Winslow and Littles is a " floating vein," lying
about GO feet above the Petersburg bed, and it is claimed that an
8-foot bed has been found by drilling about 60 to 80 feet below the
one now worked. A careful study of the available data, however,
leads to the belief that the coal at Ayrshire, Winslow, Oakland City,
and Littles all comes from the Petersburg bed, and that the 8-foot
bed below is either a newly discovered bed or the continuation of one
of the thin beds of the Brazil formation which outcrops farther east.
The coal frequently carries partings of bony coal, shale, etc., which
sometimes reach considerable thicknesses. Such a parting occurs at
Scalesville and continues to thicken southeastward, until at a mine
northwest of Folsomville it forms a parting 34- feet thick between the
two benches, but south of Folsomville it soon runs out. At several
points the coal is associated with a small overlying vein known as a
"rider." In the region between Winslow and Selvin the rider is a
6-inch vein, occurring from 5 to 15 feet above the main bed. At
Cabel a rather thick rider occurred just above the main coal, and the
two were worked together at one time, but the working did not prove
profi table.
The following analyses, made by the State geological and natural
history survey, give some indication of the chemical character of the
bed in this quadrangle. While they do not indicate a coal of very
high grade, the ease and cheapness with which it may be worked
makes it a valuable vein. The roof, as a rule, is excellent, being of
the tough, black, sheety variety which maintains itself without props
for years, even in large rooms.
Analyses of Petersburg coal.
Mini).
De Forest
Ayrshire
Blackburn
Woolley, Petersburg
Total Volatile
corn- j com-
bustible bustible
matter, matter.
84.16
82.47
87.33
85.31
39. 09
41.32
43.38
43.51
Fixed
carbon.
45.07
41.15
43.95
41.80
Mois-
ture.
6.08
10. 75
7.47
6.87
Ash.
9.76
6.78
5. 20
7.82
Sul-
phur.
Evap-
orative
effect."
2.14
0.81
5.21
3. 56
12.5
12.36
12.9
12.6
a Pounds of water evaporated per pound of coal.
Mines of small size are operated at a large number of points, and
in the aggregate have a large output. The larger mines, however, are
of necessity located near the railroads. There are perhaps 20 mines
shipping coal, the most important locations being Petersburg, Ayr-
shire, Littles, Oakland City, Massey, Cabel, Boonville, De Forest,
and Chandler. The small mines, frequently only strippings, are
especially numerous north and northeast of Winslow, south of
Augusta, west of Stendal, north and northeast of Scalesville, between
Scalesville and Folsomville, and between Folsomville and Boonville.
fullkk and ashley.] COAL FIELDS OF INDIANA AND ILLINOIS. 287
LOWER COALS.
The coals below the Petersburg bed in this quadrangle are of rela-
tively little importance. Several of them, however, reach a thickness
of 3 feet in places, are usually of a semiblock character, and on the
whole are of much better quality than the Petersburg bed. On
account of the cheapness of the coal from the latter, however, little
attempt has been made to develop the lower beds; and as natural
outcrops are very rare, their tracing is attended with much difficulty
and uncertainty, and it is only in exceptional cases that their thick-
ness and quality can be determined. While some of the coals may
locally thicken to workable beds, it does not seem probable that they
will be developed for at least a considerable length of time. The
more important of the lower beds are the Ilouchin Creek, Survant,
Velpen, Rock Creek, and Holland, although some of the still smaller
and less persistent beds have been opened occasionally.
Houcliin Creek coal. — This coal is one of the minor beds and lies
between the Petersburg and Survant coals. It is exposed in the
vicinity of Ilouchin Creek, Selvin, and Hemenway, and at other places.
Its thickness is somewhat variable. Near Hon chin Creek, south
of Cabel, and in the district northwest of Hemenway it has a
thickness of 12 inches, but at the Ileming opening north of Selvin
and elsewhere it reaches a thickness of 18 inches. It is almost invari-
ably overlain by black, sheety, bituminous shale like that overlying
the Petersburg coal.
Survant coal. — This is frequently a coal of some importance, reach-
ing a thickness of 5 feet in the hills near Gentry ville, though its
thickness is not usually over 3 feet. It lies, on an average, about 45
feet below the Houchin Creek coal and outcrops in the hills from near
Velpen, southward to near Tennyson, passing near Stendal, Selvin,
and Heilman. It is a semicoking coal, and is characteristically over-
lain by a massive sandstone or by a light-colored shale that breaks
into rhombs. At one point near Survant the interval is only 6 feet
between this coal and the coal above, but as a rule the space is at
least 30 feet. The Survant coal is probably the same as the Garrison
coal north of Tennj^son, the Taylor coal at Selvin, the Corn coal north
of Stendal, the Miller coal west of Pikeville, the coal under the bridge
at Survant, and the Hollenburg coal southwest of Velpen. The table
on page 289 includes a number of the characteristic measurements of
this coal.
Velpen coal. — At a distance of from 30 to 60 feet below the Survant
coal is the Velpen coal, one of the most persistent beds in the region.
It is frequently spoken of as "the 18-inch vein," as it maintains that
thickness with great persistency. It is characteristically covered
with a black, bituminous, sheety ^shale, above which there is often
a foot or two of limestone. The interval between it and the Survant
coal is, as far as seen, all clay shale, with the exception of the
black shale and the limestone over the lower coal and the clay under
288
CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
the coal above. The Velpen coal is abundantly exposed around
Velpen, at Pikeville, northeast and south of Selvin, and southwest
of Heilman, and is probably the coal occurring just east of Grass.
Around Selvin it is reported in a number of places to be underlain at
a distance of only a few feet by 3 feet of coal of poor quality. At no
place was this underlying coal seen. One or two thin bands of impure
coal are reported to come between the two in places. Among the
measurements taken are the following : Lynch opening, northeast of
Velpen, 18 inches; near Velpen, 30 inches; llagmyer opening, east of
Stendal, 12 inches; Byers opening, north of Selvin, 18 inches, and
Irwin opening, east of Grass, 20 inches.
Rock Greek coal.— This coal underlies the Velpen bed at an inter-
val of from 40 to 50 feet. It is usually of a better thickness than
the latter, often running up to 3 feet. It frequently, however, splits
into two benches, usually not more than a foot apart and often sepa-
rated by a mere film, though it is supposed to be in places split into
benches 5 or 6 feet apart. The thickness of the benches and of the
intervening partings are given in the table on page 290. Its outcrop
extends from near White Sulphur Springs, north of Velpen, to near
Ohrisney, passing near Velpen, Pikeville, Zoar, and Holland. It
shows as a double coal, with a parting of variable thickness at numer-
ous points, notably near Velpen, Pikeville, Zoar, west of Holland,
and throughout Warrick and Spencer continues generally.
Holland coal. — This coal normally lies from 70 to 90 feet below the
Rock Creek bed, and although it is often thin or wanting, it some-
times acquires a workable thickness. The outcrop of the coal or the
cherty limestone associated with it has been traced from a point some
3 or 4 miles north of Duff southward to Gentryville and vicinity and
eastward to Dale. The limestone outcrops abundantly southeast of
Holland, but the coal, if there, frequently fails to show in outcrop.
The thickness of the coal at various points is shown in the following
table. Where there are partings the figures given are for the com-
bined thickness of the benches.
Coal thicknesses, Millersburg, Petersburg, Survant, and Holland coals.
MILLERSBURG COAL.
Location.
Whitlock mine, west of Petersburg...
Alexander opening, south of Peters
burg
Carr opening, southwest of Rumble . .
Dongola clay and coal bank
Oakland City quarry
Bird shaft, Francisco
Tevault opening, south of Spurgeon . .
Daubs opening, east of Lynnville
Thick-
ness.
Inches.
48
56
50
30
25
30
Location.
McGladden opening, southeast of
Lynnville
Orths opening, west of Eby
Thompson mine, east of Elberfeld
Grander opening, Millersburg
Edward opening, northeast of Chan-
dler
Exposure near Ne wburg
Thick-
Inches.
36
39
63
72
58
18
fuller and ashley.] COAL FIELDS OF INDIANA AND ILLINOIS. 289
Coal thicknesses, Millersburg, Petersburg, Survant, and Holland coals — Cont'd.
PETERSBURG COAL.
Location.
Thick-
ness.
Location.
Thick-
ness.
Inches.
108
88
50
54
58
66
60
60
84
48
54
54
60
66
96
46
60
74
54
66
35
54
M
Sims opening, north of Dickey ville
McCarty opening, northeast of Dickey -
ville
Inches.
66
John Bradfield mine, north of Alfords.
Willis opening, northeast of Cato
72
Nelson opening, south of Whiteoak
Johnson opening, southwest of Cato, . .
Hodge opening, east of Dickey ville
Zint opening, northwest of Folsom-
ville.. _
48
54
Shaw opening, southeast of Winslow - .
Kelly opening, northeast of Boon ville..
Caledonia mine, east of Boonville
Reynolds opening, southeast of Boon-
ville
82
90
Harding opening, southeast of Wins-
66
Hog Branch, southwest of Survant
Day opening, west of Midway...
66
Blackburn mine, northeast of Peters-
burg.
Fettinger opening, south of Cabel
Simmons opening, southwest of Cabel.
McKinney opening, southeast of Spur-
geon
80
Smith mine, northeast of Petersburg . .
Woolley mine, Petersburg
118
108
Mine at Littles
72
Win. Stevens opening, northeast of
Carbon mine, Sophia .
54
Massey mine, east of Dongola
108
Budka opening, south of Stendal
Wilmeyer opening, south of Stendal. ..
Wildes opening, north of Scales ville...
Spradley opening, northwest of Selvin
Douglass opening, northeast of Scales-
ville
Ingleton opening, northeast of Oak-
84
Johnson shaft, Oakland City
51
56
48
Broadwell opening, northeast of Eby . .
66
Cox opening, north of Scalesville
Vicinity of Scalesville
63
87
Taylor opening, south of Boonville
48
SURVANT COAL.
Crow opening, north of Algiers
Hollenburg opening, southwest of Vel-
pen
Survant
Miller opening, northwest of Pikeville
Davis opening, southwest of Pikeville
Sickman opening, southeast of Pike-
ville
Taylor opening, near Selvin
Hemenway opening, southwest of Sel-
vin
Garrison opening, north of Tennyson .
Fisher opening, southeast of Tennyson.
HOLLAND COAL.
Highway north of Duff
Payne opening, east of Velpen
Stoncamp opening, west of Duff
Coto opening, south of Duff
Cooper opening, southeast of Holland
Tormohlen opening, southwest of Hol-
land.
Romines opening, east of Gentry ville.
Woods opening, southwest of Dale
Brant opening, southeast of Chrisney.
Bull. 213— OS-
lO
290 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
Thicknesses of benches and partings of the Rock Creek coal.
Location.
Gray opening, Bertr Creek, north of Otwell.
Proman opening, northeast of Velpen
Rock Creek, northeast of Pikeville —
Ilert opening, southeast of Pikeville.
District west of Duff
Myers opening, east of Stendal
Hildebrand opening, east of Stendal
District east of Zoar
District west of Holland
Thickness Thi k
Inches.
Inches.
Thickness
of lower
bench.
Inches.
18
24
12
3
8 +
2
Total
thickness
of coal.
Inches.
21
44
24
15
20+
8
40
28
24
GEOLOGIC STRUCTURE.
Rather pronounced local dips are occasionally found, but a careful
tracing- of the Petersburg and Millersburg coals by outcrops, wells,
or shafts, shows that although there are many irregularities and even
reversals, the general dip is nearly west, the amount varying from 15
to 40 feet, with an average of about 20 feet to the mile. As a result
of that dip the coals disappear one after another beneath the surface
to the west, and at the western limits of the area are from about 50
feet, in the case of the Millersburg, to nearly 500 feet, in the case of
the Holland coal, beneath the level of the bottom of the deepest val-
leys. The depth of the Petersburg coal below the valley bottoms in
the western part of the quadrangle appears to vary from 150 to about
200 feet.
COALS OF THE PATOKA QUADRANGLE.
COAL AND LIGNITE IN INDIANA.
Coal. — With one or I wo exceptions none of the coals outcropping in
that portion of Indiana included in the Patoka quadrangle are now
worked, even for local supply, though temporary openings have fre-
quently been made in the past. The one mine in the area — the Oswold,
at Princeton — gets its supply from a bed supposed to be the Peters-
burg, reached by a shaft at a depth of about 440 feet. The coal aver-
ages about 6 feet 6 inches in thickness. The mines working the same
bed at Evansville are just outside the quadrangle.
A considerable number of deep borings have been made at Prince-
ton and elsewhere, in which coals of some thicknesses were encoun-
tered. Some of these are given on the following table :
fuller and Ashley.] COAL FIELDS OF INDIANA AND ILLINOIS. 291
Depth and thickness of coals in deep wells.
Town.
Location.
Depth.
Thick-
ness.
Feet.
Feet.
Princeton
Kurtz place ______ _ _ _
( 146
I 258
1
a*
r 199
2
Do_
Southern Railway shops _ _ _ _ _ _
| 346
7
451
2
f 365
6
470
6
Do...
Hall place. _ .
670
730
6
7
1,020
3
r 62
H
Do
Evans place
281
402
i
6
I 514
6
f 80
n
283
3
422
7
Do_._
Near preceding. _
471
7
593
4
628
31
670
4
82
1
281
2
Do
Tompkins place _
396
462
6
5
604
6
I 723
6
f 44
1
Hazelton
Thorn place _
105
221
1
4
Do.__.
Top of bluffs 2 miles east of town
( 116
I 172
"ST
r 56
1
Fort Branch
Peter Hoffman place _ - - -
178
5
[ 250
3i
Do
Grove mill _ _
( 301
I 408
5
7
Haubstadt
Sec. 3, T. 3 S., R. 11 W ,
| 60
I 80 to 100
2
4
292 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull 213.
A coal sometimes reaching a thickness of 18 to 24 inches outcrops
near the levels of the flats along the tributary of the Patoka River,
northeast of Princeton, and near Townsend's quarry, north of the
Patoka. It was formerly opened by strippings at several points.
Two or more very thin coals show in the river bluff south of Patoka,
one of which also outcrops near the base of the sandy bluffs H miles
northwest of the town. A coal of variable thickness occurs along the
bluffs bordering the White River, east of Hazelton, and is now being
worked locally on a limited scale. This coal is not found at Hazelton,
but about 2 miles northwest of the town it outcrops with a thickness
of 3| feet in the banks of the White River, and is now worked by a
stripping at the Wharf mine. Very thin coals occur in the Gorden
Hills, near the dam at Grand Rapids, in the hills 2 miles southwest
of Princeton, and at several points northeast of Owensville. A coal
reaching a thickness ol* several feet is reported in the the Mumford
Hills. With the exceptions noted above, none of the occurrences
mentioned have been developed.
In the southwestern portions of Vanderburg and in southeastern
Posey County there is a rather persistenl coal, lying about 100
feet above the main limestone (Somerville) of the region. Where
pure it is but a few inches in thickness, but where shaly it sometimes
increases to is inches or more. Il is associated with a thin limestone
and appears t<> be persistenl for a considerable number of miles.
West of Blairsville and Lippe this coal disappears below the sin-face
and is succeeded by another small coal of similar character and asso-
ciation about 70 feet higher up. rl nis can be traced to a point west,
of the Mount Vernon division of the Evansville and Terre Haute
Railroad, where the ouicrop disappears beneath a deep covering of
glacial drift, loess, and marl. Both coals have been worked occasion-
ally for fuel for thrashing machines, but are not worthy of systematic
development.
Lignite. — Coals from a few inches to a foot in thickness have been
reported from a large number of the wells sunk in the glacial drift of
the Patoka area. No samples were seen, but from the descriptions the
material would seem to be a poor grade of lignite. The lignites appear
to occur in a dark-grayish clay, usually reported as "blue mud," but
they are also associated with water-bearing gravels in several
instances. Though apparently sometimes overlaid by till, the beds
associated with the lignites are probably water deposited.
COAL IN ILLINOIS.
Friendsville coal, — Only one coal has been mined in the portion of
Illinois included in the quadrangle, though several smaller coals with
thicknesses varying from 6 to 18 inches have been opened. These,
however, are not persistent. The Friendsville coal outcrops near
Friendsville and possibly at a few other points, but has seldom, if
puller and ashley.] COAL FIELDS OF INDIANA AND ILLINOIS. 293
ever, been opened on itsouterop. It underlies the surface of Wabash
County at a moderate depth from a point north of Friendsville south-
ward to Bellmont and Keensburgaud westward to the bottom land of
Bonpas Creek. No coal which could be correlated with the Friends-
ville bed has been recorded in the wells near Bonpas Creek, with the
possible exception of one point southwest of Cowling. It has not been
found in Edwards County. Neither has it been recognized at Mount
Carmel nor southward along the Wabash River above Rochester,
and there is every evidence that it has pinched out and disappeared.
A deep drilling at Grayville, made expressly for information regard-
ing coals, failed to find any over a few inches in thickness, indicating
that the Friendsville vein has disappeared to the southwest as well as
to the west and east.
The Friendsville coal maintains rather persistently an avTerage
thickness of about 3 feet. It is mined by shafts 1 mile east of Friends-
ville, 2 miles southeast of Friendsville, 1| miles south of Bellmont, and
at McClearys Bluff, on the Wabash River. It has been mined in the
past at Sugar Creek, Maud, and at several points northwest of Mount
Carmel. The coal burns moderately freely, but has a large ash con-
stituent and does not coke.
The dips of the Friendsville coal are more irregular in character
but less in amount than those exhibited by the coals in Indiana. The
general dip, however, is still to the west. The highest altitudes at
which the coal occurs is from 450 to 460 feet, these altitudes being
reached at a number of points between Mount Carmel and Friends-
ville. East of Friendsville the altitude of the coal declines to 400 feet
or less near Crawfish Creek, while to the west, southwest, and south
the gentler but more persistent dip carries it downward to an altitude
of about 350 feet in the vicinity of Cards Point, 385 feet at Maud, 395
feet at Bellmont, 360 feet at Keensburg, 370 feet at Rochester, and
335 feet 1^ miles southwest of Cowling.
GEOLOGICAL SURVEY PUBLICATIONS ON COAL, LIGNITE, AND PEAT.
A number of the more important United States Geological Survey
publications on the subjects of coal, lignite, and peat are listed
below:
Ashley. G. H. The Eastern Interior coal field [Illinois and Indiana]. In
Twenty-second Ann. Rept., Pt. Ill, pp. 265-300. 1902.
Bain, H. F. The Western Interior coal field [Iowa, Missouri, Kansas]. In
Twenty-second Ann. Rept., Pt. Ill, pp. 333-360. 1902.
Brooks, A. H. The coal resources of Alaska. In Twenty-second Ann. Rept.,
Pt. Ill, pp. 517-571. 1902.
Campbell, M. R. Geology of the Big Stone Gap coal field of Virginia and
Kentucky. Bulletin No. 111. 106 pp. 1893.
Campbell, M. R., and Mendenhall, W. C. Geologic section along the New
and Kanawha rivers in West Virginia. In Seventeenth Ann. Rept., Pt. II, pp.
473-511. 1896.
Chance, H. M. Anthracite coal mining. In Mineral Resources U. S. for
1883-84, pp. 104-143. 1885.
Dall, W. H. Report on coal and lignite of Alaska. In Seventeenth Ann.
Rept., Pt. I, pp. 763-808. 1896.
DlLLER, J. S. The Coos Bay coal field. Oregon. In Nineteenth Ann. Rept.,
Pt. Ill, pp. 309-370. 1898.
Haseltine, R. M. The bituminous coal field of Ohio. In Twenty-second Ann.
Rept., Pt. Ill, pp. 215-226. 1902.
Hayes, C. W. The coal fields of the United States. In Twenty-second Ann.
Rept., Pt. III. pp. 7 21. 1902.
The southern Appalachian coal field [Alabama, Georgia, Tennessee,
Kentucky, Virginia]. In Twenty-second Ami. Rept., Pt. Ill, pp. 227-264. 1902.
Lane, A. C. The Northern Interior coal field [Michigan]. In Twenty-second
Ann. Rept.. Pt. Ill, pp. 307-332. 1902.
Shaler, N. S. Origin, distribution, and commercial value of peat deposits. In
Sixteenth Ann. Rept., Pt, IV, pp. 305-314. 1895.
Smith, G. O. The Pacific coast coal fields [Oregon, Washington, California].
In Twenty-second Ann. Rept., Pt. Ill, pp. 473-514. 1902.
Stoek, H. H. The Pennsylvania anthracite coal field. In Twenty-second Ann.
Rept., Pt. Ill, pp. 55-118. 1902.
Storrs. L. S. The Rocky Mountain coal fields [Montana, Wyoming, Colorado,
Utah, New Mexico]. In Twenty-second Ann. Rept., Pt. Ill, p. 415-472. 1902.
Taff, J. A. Geology of the McAlester-Lehigh coal field, Indian Territory. In
Nineteenth Ann. Rept., Pt. Ill, pp. 423-600. 1898.
Preliminary report on the Camden coal field of southwestern Arkansas.
In Twenty-first Ann. Rept,. Pt. II, pp. 313-329. 1900.
The Southwestern coal field [Indian Territory, Arkansas, Texas]. In
Twenty-second Ann. Rept., Pt. Ill, pp. 367-414. 1902.
Taff, J, A., and Adams, G. I. Geology of the eastern Choctaw coal field,
Indian Territory. In Twenty-first Ann. Rept., Pt. II, pp. 257-311. 1900.
294
PUBLICATIONS ON COAL, LIGNITE, AND PEAT. 295
Vaughan, T. W. Reconnaissance in the Rio Grande coal field of Texas. Bul-
letin No. 164. 100 pp. 1900.
Weeks, J. D. The manufacture of coke. In Mineral Resources U. S. for
1883-84, pp. 144-213. 1885.
White, D. The bituminous coal field of Maryland. In Twenty-second Ann.
Rept.. Pt. Ill, pp. 201-214. 1902.
White, D., and Campbell, M. R. The bituminous coal field of Pennsylvania.
In Twenty-second Ann. Rept., Pt. Ill, pp. 127-200. 1902.
White, I. C. Stratigraphy of the bituminous coal field of Pennsylvania, Ohio,
and West Virginia. Bulletin No. 65. 212 pp. 1891. {Out of print.)
Willis, B. The lignites of the Great Sioux Reservation [Dakota] . Bulletin
No. 21. 16 pp. 1885.
Some coal fields of Puget Sound [Oregon] . In Eighteenth Ann. Rept. ,
Pt. Ill, pp. 393-436. 1898.
Woodworth, J. B. The Atlantic coast Triassic coal field [Virginia, North
Carolina]. In Twenty-second Ann. Rept., Pt. Ill, pp. 25-54. 1902.
OIL, GAS, AND ASPHALT.
A number of papers describing the results of recent field work by
the Survey in various oil, gas, and asphalt fields are here presented.
In addition to this new material, a chapter on the origin and distribu-
tion of asphalt and bituminous rocks in the United States is here
reprinted, in greatly condensed form, from a detailed publication on
that subject issued by the Survey in 1902. This has been done, as
the portion reprinted serves as an excellent summary of the subject,
and as an introduction to the other papers on asphalt here included.
ORIGIN AND DISTRIBUTION OF ASPHALT AND BITUMINOUS
ROCK DEPOSITS IN THE UNITED STATES.
By Gr. H. Eldridge.
CLASSIFICATION OF HYDROCARBONS.
The classification of W. P. Blake, slightly modified, follows.
Classification of natural hydrocarbons.
, Gaseous /Marsh gas.
\" Natural gas."
Fluid /Naphtha.
I Petroleum.
Maltha.
Viscous ( malthite)
Bituminous
a
o
z
W
Solid
Asphaltite.
I Coal
Mineral tar.
Brea.
Chapapote.
Elastic jElaterite (mineral caoutchouc)
I Wurtzilite."
Albertite.
Impsonite.
Grahamite.
Nigrite.
Uintaite (gilsonite).
Lignite.
Bituminous coal.
Semibituminous coal.
Anthracite coal.
{Succinite (amber).
Copalite.
Ambrite, etc.
Cereous _ / Ozocerite .
IHatchettite, etc.
Crystalline . /Fichtelite.
lHartite, etc.
Resinous
296
" Wurtzilite might, perhaps, better be classed with the asphaltites.
bldridoe.] ASPHALT AND BITUMINOUS EOCK DEPOSITS.
297
Classification, or grouping, of natural and artificial bituminous compounds.
Mixed with limestone (''asphal- rSeyssel, Val de Travers, Lobsan, Illinois,
tic limestone "). I Utah, and other localities.
Mixed with silica and sand ("as- r California, Kentucky, Utah, and other
PQ
phaltic sand'').
Mixed with earthy matter ("as-
phaltic earth " ) .
Bitnminons schists
I localities. " Bituminous silica."
•J Trinidad, Cuba, California, Utah.
jCanada, California, Kentucky, Virginia,
and other localities.
pn • , J Thick oils from the distillation of petro-
leum. ''Residuum."
Viscous.
Gas tar.
Solid
I Pitch.
Refined Trinidad asphaltic earth.
Mastic of asphaltite.
Gritted asphaltic mastic.
Paving compounds.
A glance at the above tables will convince one of the impossibility
of establishing hard and fast lines between the substances enumerated.
The classification, however, seems to the writer to be the most satis-
factory of the several attempts met with in the literature of the
subject.
It will be observed that there has been omitted from the table one
of the commonest terms in use, ' ' asphalt," or ' ' asphaltum. " By many
disinterested authorities this word is restricted to the solid forms of
the purer bitumens, forms including those grouped by Professor Blake
under the general derivative, "asphaltite." This usage is reasonable,
and by adhering to it confusion will be avoided in both science and
trade. Industrially, however, the word "asphalt" is unfortunately
made to include almost every compound of bitumen with a foreign
material, chief among the latter being sandstone and limestone.
Mr. Clifford Richardson, in his Nature and Origin of Asphalt, a
contribution (October, 1898) from the laboratory of the Barber
Asphalt Paving Company, gives the following definition of asphalt :
The natural bitumen, which is known as asphalt, is composed, as far as we have
been able to learn, of saturated and unsaturated dicyclic, or «polycyclic, alicyclic
hydrocarbons and their sulphur derivatives, with a small amount of nitrogenous
constituents. Asphalt may, therefore, be defined as any hard bitumen, composed
of such hydrocarbons and their derivatives, which melts on the application of heat
to a viscous liquid; while a maltha or soft asphalt may be defined as a soft bitu-
men, consisting of alicyclic hydrocarbons, which, on heating, or by other natural
causes, becomes converted into asphalt. The line between the two classes can
not be sharply drawn.
- "Bitumen," also, is a term that has been omitted from the table,
although its adjective, "bituminous," is employed. The word
a In the original report the word "or" was inadvertently placed after instead of before
" poly cyclic.1'
298 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
"bitumen " has in the main been used to include the three varieties of
hydrocarbon compounds known as petroleum, maltha or mineral tar,
and the solid substances included under the asphaltites and often
designated, one or another of them, ' ' asphalt. " The adjective ' ' bitu-
minous," however, may be applied to a sandstone or other rock
impregnated with bitumen, as thus understood; and if such bitumen
has any of the characteristics of the so-called asphalts, the compound
may receive the name "asphaltic sandstone," "asphaltic limestone,"
etc.
GENERAL FEATURES OF THE HYDROCARBONS.
The relations, chemical or other, between the hydrocarbons of the
table on pages 297-298, were they worked out, would doubtless show the
utmost complexity, for complexity exists even in the substances them-
selves, nearly all of which are separable by the action of solvents or
by fractional distillation into two or more components that are in turn
divisible into series of hydrocarbons, in many instances of great
extent.
In Dana hatchet t ite and ozocerite are found among the simple hydro-
carbons as members of the paraffin series C„Il2„+2, while fichtelite,
hartite, and a number of others occur in this division of the hydro-
carbons, but of series other than the paraffin, and in many instances
altogether of doubtful reference.
The resinous compounds belong to the class of oxygenated hydro-
carbons, the membership in which is very extended and of great
variety. Concerning this class, Dana remarks that it embraces
"chiefly the numerous kinds of native fossil resins, many of which are
included under the generic term 'amber;' also other more or less
closely related substances. In general, in these compounds, weak
acids (succinic acid, formic acid, butyric acid, cinnamic acid, etc.), or
acid anhydrides, are prominent."
Between the coals — especially the bituminous and cannel varieties —
and the resinous and asphaltite divisions of this table relations are
readily found ; indeed, for a number of years, only two or three decades
ago, grahamite, on account of its composition, was regarded by men
high in authority as a true coal, notwithstanding its wholly different
mode of occurrence.
Albertite, grahamite, uintaite, etc., are now accepted as closely
related varieties of asphaltum. This relationship is evident both in
their chemical composition and in their mode of occurrence, yet they
are readily distinguished by their behavior toward solvents, by the
action of heat upon them — their fusibility, so called — and by other
properties.
Wurtzilite, in outward appearance, bears a striking resemblance to
the asphaltites, but is distinguished from them by its behavior toward
solvents and by its marked sectile and elastic properties. Yet, while
,
iLDRiDGE] ASPHALT AND BITUMINOUS ROCK DEPOSITS. 299
of lintaite itself is exceedingly brittle, one of its leading features, devel-
>ped in the manufacture of black japans and varnishes made from it,
s this very property of elasticity, attainable in such perfection in no
)ther hydrocarbon compound except elaterite and wurtzilite.
Elaterite, though elastic, is quite distinct from wurtzilite. Dana,
n remarking upon the results attained by the authorities which he
consulted, states that this substance "appears to be partly a carbo-
lydrogen near ozocerite and partly an oxygenated insoluble material."
The viscous bitumens of the table vary markedly in consistency.
Maltha has the greatest fluidity, brea and chapapote the least — these
ire, in fact, solids. Each member of the group shades into the next
m either side, even maltha into petroleum and chapapote into the
isphaltites. From this it will be inferred that the application of the
several terms is decidedly indefinite. In regard to brea and chapa-
pote, usage seems to make them synonymous, unless it be that the
solidity of chapapote is a degree greater than that of brea, by no
means an assured distinction.
The viscous compounds stand between the solid asphaltites on the
one hand and petroleum on the other. "The fluid kinds," observes
Dana, "change into the solid by the loss of volatile matter by a proc-
ess of oxidation which is said to consist first in the loss of hydrogen
and finally in the oxygenation of a portion of the mass."
Richardson, in his Nature and Origin of Asphalt, observes:
Asphalts are distinguished by the large amount of sulphur they contain, and it
is to its presence that many of the important characteristics, and perhaps, in part,
the origin of this form of bitumen, is due. The soft asphalts or malthas contain
much less sulphur than the harder ones, or if the former are rich in sulphur, they
are then in a transition stage and will eventually become hard. But a small por-
tion of the constitutents of a hard asphalt are volatile even in vacuo, but they can
| be separated by solvents into an oily portion, which is soft, or softens readily when
heated, and a harder portion, which does not melt by itself without decomposition,
and is a brittle solid, but soluble in the oily or softer portion. The harder and
least soluble portion always contains the larger part of the sulphur. It seems,
therefore, that sulphur is the effectual hardening agent of [many] natural asphalts,
in the same way that it is of artificial asphalts which are produced by heating a
soft natural bitumen with sulphur.
But Mr. Richardson adds that "some natural bitumens occur which
have become hardened in another way and perhaps by oxygen." This
refers particularly to the asphaltites.
Boussingault's investigation, in 1837, into the composition of asphalt
also developed son 3 results of especial interest. He took for his
experiments the viscid bitumen of Pechelbronn, France. At a temper-
ature of 230° C, in an oil bath, he separated an oily liquid, to which
he gave the name "petrolene," regarding it as the liquid constitu-
ent of bitumen, which, mingled in varying quantities with a solid sub-
stance, "asphaltene," forms the bitumens of different degrees of
fluidity. He describes asphaltene as brilliant black in color and luster,
300 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213;
with a conchoidal fracture, and heavier than water. Toward a tem-
perature of 300° C. it becomes soft and elastic. It begins to decom-
pose before it melts, and burns like the resins, leaving an abundance
of coke.
Dana, in his System of Mineralogy, quotes several analyses of
petrolene by Boussingault, one of which gives C. 87.45, H. 12.30..
DISTRIBUTION OF THE ASPHALTS AND BITUMINOUS ROCKS OF
THE UNITED STATES.
The distribution of asphalts and bituminous rocks in the United ;
States is wide. The asphaltites are found in West Virginia, Indian
Territory, Colorado, and Utah; bituminous limestones in Indian Ter-
ritory, Texas, and Utah; bituminous sandstones in Kentucky, Mis-
souri, Indian Territory, Texas, Utah, and California; a earthy bitu-
men of greater or less purity, occurring as veins, in California; while
brea may occur in all petroleum areas, but in the present investiga-
tion was found only in Indian Territory, Wyoming, and California,
although small bodies are reported in Montana.
The stratigraphic range of the bitumens and their compounds is as
wide as their geographic distribution. Their oldest association |
observed is with the Ordovician shale of the Tenmile region in eastern
Indian Territory, where impsonite, an asphaltite closely related to
albertite, occurs in vein form. Other veins of like material, as well
as a bituminous sandstone, occur in the series of Ordovician sand-
stones overlying the shales along the Indian Territory- Arkansas line.
In central Indian Territory, in the Buckhorn district, are other bitu-
minous sandstones, also of Ordovician age, though perhaps not to be
correlated with the foregoing. Above these, in direct succession, is
the summit limestone of the Ordovician, at least for this locality — a
massive bed of variable thickness, the maximum being approximately
400 feet. The entire body of rock is varyingly impregnated with bitu-
men, the more highly enriched portions to an average of 6 to 8 per
cent. In this same locality the Lower Coal Measures also, at one or
more horizons, are richly infiltrated with bitumen, one of their lime-
stones carrying an average of 14 per cent. The Lower Coal Measures
are unconformable with the underlying formations, and the occur-
rence of bitumen at the several horizons suggests a common source and
origin for it, and an inflow to its present reservoirs, perhaps subse-
quent to the laying down of all the sediments involved, if not, indeed,
subsequent to their folding. On the other hand, from the presence
in the Coal Measure conglomerate of an occasional pebble, believed to
be of Ordovician bituminous sandstone, particularly observed by Mr.
Taff, there may have been two or more distinct flow periods.
West and south of the Arbuckle Mountains the Coal Measures again
a Since the writer's field investigation indefinite accounts of bituminous sandstones in Alabama
and Illinois have appeared in certain newspapers.
bldridge] ASPHALT AND BITUMINOUS ROCK DEPOSITS. 301
cany bitumen in some of their members — grits and limestones. These
horizons, however, may be quite different from those in the Buckhorn
region.
Near Higginsville, Mo., the Warrensburg sandstone, which occu-
pies what Mr. Arthur Winslow, the State geologist, considers a channel
of erosion in the Coal Measures, and which is assigned to the Car-
boniferous, is also infiltrated with bitumen to about 6 per cent.
In West Virginia the grahamite vein, which has brought much
renown to the region of its occurrence, occupies a vertical fissure in
the Waynesburg sandstone and adjoining beds above and below,
all of which are horizons in the Upper Productive and Upper Barren
Coal Measures of the Carboniferous age.
The bituminous sandstones of Kentucky are closely successive
members of the Chester formation and the basal portion of the Coal
Measures, and all, at one point or another, are impregnated to a
degree sufficient to render them economically available for paving
purposes, their contents ranging between 5 and 9 per cent.
The Permian, or what is at j>resent accepted as the Permian, in
central Indian Territory has been penetrated by fissures, through
which petroleum has risen into its surficial sandy members and
has also been converted to brea as surface deposits. This occurs at
Wheeler, a settlement about 40 miles west of Ardmore. The locality
is practically that of the enriched Coal Measure sandstones south of
the Arbuckle Mountains, and there is little doubt that a common
source supplied all the different horizons that now constitute the
exposed storage reservoirs of the former fluid petroleum.
The Trinity sand of the Lower Cretaceous is a bitumen-bearing for-
mation at many points in its area of outcrop in southern Indian Ter-
ritory and northern Texas. This is particularly the case where it
rests upon the Carboniferous, an occurrence that is significant of the
derivation of its bitumen from a source perhaps identical with that
from which the several members of the Coal Measures have derived
theirs.
The Glenrose formation, also a member of the Trinity division of
the Lower Cretaceous, in one of its limestones carries the bitumen
of the deposits of Post Mountain, near the town of Burnet, Burnet
County, Tex. The Anacacho formation of the Texas Upper Cretace-
ous, corresponding to a horizon near the base of the Montana of the
Rocky Mountain section, carries the rich bituminous limestones
extensively quarried in the vicinity of Anacacho Mountain, 18 miles
west of Uvalde, in southern Texas. In this connection the presence
of important oil horizons in the Montana formation of the Florence
oil field in Colorado is not unworthy of note.
The Middle Park formation of Middle Park, Colorado, largely a
terrane of eruptive material and a correlative of the Denver of the
plains — a formation for the present termed post-Laramie, without
302 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213^
assignment to Cretaceous or Tertiary — also carries bitumens. The
deposit occurs in the northern portion of Middle Park, almost in the
heart of the Rocky Mountains. It is here an asphalt resembling gil
sonite and occupying an irregular fissure or series of fissures in the
clays, sandstones, and conglomerates of the formation referred to.
The occurrence is, so far as known, limited to the immediate region
in which it is found, and is thus comparatively isolated, the nearest!
asphalt being the gilsonite found along the Colorado-Utah line, 150ji
miles distant.
The bitumens of the Tertiary horizons are apparently confined to
the West — to Colorado, Utah, and California. The various divisions
of the Eocene in eastern Utah and just across the line in Colorado are
noted both for the variety of their asphalts and for the size of their
veins. It is in this region, of the White and Green rivers and the
celebrated Book Cliffs, that the great veins of uintaite are found andj
that the minor seams of wurtzilite, ozocerite, and nigrite occur.
Bituminous limestones are also of wide distribution, though confined
to the Green River shales. The asphaltites occur in fissures both in
this formation and in those overlying, especially the Bridger and
Uinta. Maltha springs also occur, and even petroleum is reported
in one of the members of the Cretaceous, a few miles east of the
Utah-Colorado line. The Green River shales are noted throughout
the West for their bitumen contents, and it is surmised that they are
the source of the asphalts, at least, of this vast area. The variation
in the ultimate material as it to-day fills one fissure or another is per-
haps due in part to a change somewhat allied to fractional distillation
in petroleum technology and in part t<> the degree to which oxygen
absorption lias been carried on. In any event, the variety of bitumen
found can hardly excite wonder when considered as to the origin of
the material and the differentiations that take place in artificial dis- j
filiation. It is, indeed, to be expected.
The occurrence of bitumens in the Neocene is confined to California.
The rocks of this period here embrace a heavy series of shales with
local sandstones, tuffs, etc. — the Monterey formation; a conspicuous
body of massive sandstone with a minor proportion of shales, known
as the San Pablo formation, but in doubt as to its position as a mem-
ber of the Miocene or Pliocene, and hence in the region of its occur-
rence regarded as Middle Neocene; and a succession of sandstones,
conglomerates, and clays, probably Pliocene, but for the present
termed Upper Neocene, with the specific name Paso Robles assigned
to it.
In addition to the foregoing, there are certain and important sand-
stones and sand aggregates of somewhat doubtful age, but where
encountered seeming to lie beneath the shales of the Monterey rather
than in them, and often against and upon granite. Such is their
occurrence in the vicinity of Santa Cruz, and again at one or two points
i kldeidge] ASPHALT AND BITUMINOUS ROCK DEPOSITS. 303
in the range bordering the Salinas Valley on the east. These sand-
stones are locally heavily impregnated with bitumen, and near Santa
Cruz are extensively quarried for paving purposes in San Francisco
and elsewhere.
The Monterey formation is of particular importance, in that for
almost the entire length of the State its terrane is more or less con-
spicuously marked with petroleum or maltha seepages, while its sandy
members may appear as minor storage reservoirs of oil, these now
altered at the outcrop to a material of pasty consistency, which forms
with the sand grains an asphaltic compound of considerable richness.
| Such sandy beds occur at Point Arena, in the San Antonio Valley,
and in the region of the Sisquoc. The shales of the Monterey are not
only generally bituminous, but some of their more arenaceous and
porous members are also especially rich, doubtless having received
an inflow of petroleum from their adjoining and less open associates.
It is in the shales of the Monterey, too, as well as in the Middle Neo-
cene, that veins of the more solid bitumens, mixed with elastic mate-
rial derived from the country rock, are found. Except for the clastic
material, the bitumen would resemble in structure the asphaltites,
though still differing from them in other features. Veins of this
description are conspicuous in the vicinity of Santa Maria, Santa
Barbara, and Asphalto. Near the latter place the asphaltic material
is intimately related to, even associated with, petroleum.
The San Pablo formation, at least that portion of it in the San Luis
Range, has been converted into a vast storage reservoir. It is the
surface terrane over an area of nearly 50 square miles a short dis-
tance southwest of San Luis Obispo, and perhaps half its outcrop here
shows impregnation with bitumen in greater or less degree, locally
to a high degree. In the same region scattered bodies of the Paso
Robles formation have also been infiltrated where resting on the San
Pablo or the Monterey.
The San Pablo is also, perhaps, represented in the region of the
Sisquoc, 40 miles southeast of Santa Maria, where along the southern
base of the San Rafael Range is a highly enriched body of sandstone,
of doubtful correlation from its structural association with recognized
Monterey sandstones, but possibty of the age suggested. It is locally
one of the richest sandstones in California.
In the region of La Graciosa Hills, 0 to 10 miles south of Santa
Maria, there rests upon the Monterey, unconformably, a heavy body
of loosely coherent sands or sandstone commonly regarded as Plio-
cene. Cracks have developed in the formation, and have been
filled with bitumen carrying from 30 to 60 per cent of clastic matter.
The material resembles in general appearance that already referred
to as of vein form in the Middle Neocene near Asphalto. Here,
again, it has been found in association with petroleum.
Post-Pliocene sandstones are found with small gash veins and
b
304 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
other irregular but more or less extensive bodies of the solid bitu-
mens in the region of Mores Landing, 7 miles west of Santa Barbara.
A material in many ways resembling gilsonite was found as a minute
pocket in the sandstone, but the mass of the bitumen is of the solid
variety, mixed with 20 to 40 per cent of clastic material. Twelve
miles east of this occurrence is the important petroleum-producing
region of Summerland. Pleistocene or Recent sands have been heav-1
ily charged with bitumen at Carpinteria, 12 miles east of Santa Bar- i
bara. They have been for the most part removed, but the continuous | ,'
flow of maltha in the floor of the quarry would quickly impregnate an ..
equal body were the excavation to be filled with fresh sand from the |
adjoining ocean beach.
Surficial deposits of brea are well distributed over the United
States. Those observed by the writer were in Indian Territory,
Wyoming, and California, the first no longer increasing from active
springs, the others still forming. The source of their malthas is
naturally extremely varied. In addition to the above, there are doubt-
less many others of but little less importance scattered through the
oil regions of the country.
ORIGIN OF THE DEPOSITS.
The origin of the hydrocarbons and bituminous compounds may be
traced, the writer believes, to petroleum. This is a natural inference
from chemical relations. The fact that there may be a wide variation
in the composition and physical aspect of the bitumens, whether of
asphaltites or of sandstones, matters not, for important differences
are found in petroleums themselves ; the variation in the asphaltites,
indeed, may be somewhat more marked, for in Die passage from
petroleum to its derivatives the process may have stopped at any
point, with a corresponding development of physical as well as chem-
ical distinctions. But in the geologic investigation of the asphaltites,
bituminous sandstones, and related materials the view of their origin
suggested by chemistry has in many ways been reenforced. The
asphaltic earths, and solid bitumens in part, are frequently associated
with active petroleum springs, or are found in regions renowned as
oil producing. The sandstones and limestones are found resting upon
formations conspicuous for their yield at other points; indeed, in one
instance they were found upon a formation actively yielding oil directly
beneath them, and this at the present day. The sandstones, therefore,
can hardly be regarded other than as storage reservoirs for the oil
thus received; the limestones, it is sometimes thought, may have been
the locus of origin as well as of storage.
The asphaltites and closely associated hydrocarbons — ozocerite, for
example— can hardly have been derived otherwise than by the draining
of petroleum pools or strata richly saturated with oil. In the case of
gilsonite, the absence of every trace of petroleum in the inclosing sand-
ldbidgb.] ASPHALT AND BITUMINOUS ROCK DEPOSITS. 305
tones and its evident prevalence in the underlying Green River shales
ndicate the latter series as the one-time source of the oil which on
sntering the fissures was converted into the asphaltites. Moreover,
ocally, for a foot or two adjacent to the veins, the sandstone is filled
vith interstitial gilsonite, which is evidence of infiltration from the
ietrolenm-filled fissure into the sandstones rather than into the fissure
:rom the rock on either side. The channels by which the shales were
Irained are cracks that extend from the bottom of the main portion of
;he fissures, in some instances several hundred feet, into the underlying
)itumen-bearing beds, but even here the draining of the strata must
have been marvelously rapid to have been so complete as the condi-
tions indicate before being interfered with by the closing of the fis-
sures from the settling or readjustment of the shale, always a rock of
exceeding instability. The writer believes, however, that the filling
of the fissure could have been derived from no other source. The
origin of the cracks is, of course, well understood. They occur in all
formations and in all localities and are a concomitant feature of fold-
ing, though perhaps at times developed from shrinkage
In the filling of all reservoirs, whether fissures or sandstones, the
investigator is struck Avith the almost inevitable slowness of the proc-
ess and the vastness of the area of fine-grained sediments that must
have been drained to yield the supply absorbed. Then, too, in the
case of the asphaltites the hardening must have been very gradual, the
material passing through a viscous stage, during which fragments
dropped from the walls into the bitumen and yet were supported, even
as a rock is supported upon the surface of a thickening maltha pool at
the present day. After solidification was complete the crushing strains
from readjustment of the strata became manifest in the penicillate
structure developed in the asphalt next to the walls of the vein. It is
probable that during the filling of the crack this readjustment was
continuously going on, but it could become evident only after the vein
material had been hardened sufficiently to record it.
Bull. 213—03 20
THE PETROLEUM FIELDS OF CALIFORNIA.
By G. H. Eldridge.
INTRODUCTORY.
The petroleum fields of California, as at present known, lie on
either side of the Central Valley of the State, in the Coast Range, and
along the Pacific front. The greatest development has taken place
south of the parallel of San Francisco, although northward from this
are many prospects and one developed field of minor commercial
importance — that in the vicinity of Eureka, Humboldt County.
The Coast Range, considered as a topographic province, includes
all the mountains lying between the great Central Valley of California
and the Pacific Ocean. It has no well-defined axis, either topographic
or geologic, but consists rather of a number of parallel ridges having
a general elevation of between 3,000 and 4,000 feet, with occasional
peaks extending to somewhat greater heights.
Structurally the Coast Range consists of numerous parallel anti
clines and their corresponding synclines. There is no dominant
axial fold, the crust having been crumpled into a close succession of
ridges of varying amplitude and height of arch. The topographic
trend of the general range from San Louis Obispo north is about
N. 30° W., veering westward south of this. The structural trend of'
the folds composing it, however, is between N. 20° and 40° W. from
the thirty-sixth parallel north, N. 50° or 60° W. in the region of San
Luis Obispo, and from Point Conception east N. 80° to 90° W.
Throughout the entire range it is distinctly diagonal to the coast line,
except, perhaps, along the Santa Barbara Channel. Faults, of course,
occur.
The large productive oil fields of southern California include the Oil
City, adjacent to Coalinga; the McKittrick ; the Sunset and its exten-
sion, the Midway; the Kern River; La Graciosa; the Suminerland;
the Santa Clara Valley; the Los Angeles; and those of the Puente
inns.
THE OIL FIELDS.
COALINGA DISTRICT.
This district extends along the eastern base of the Mount Diablo
Range for a distance of about 30 miles, Coalinga, the small town from
806
eldridge] PETROLEUM FIELDS OF CALIFORNIA. 307
which it is named, lying somewhat nearer the northern end. Three
areas of oil development exist, which may be designated the Oil City
field, the Kreyenhagen field, and the Avenal field, but the first only
is of special productiveness. Coalinga is accessible by rail from the
main lines of both the Southern Pacific and the Atchison, Topeka
and Santa Fe railroads.
The topographic features of the region are those of a high, rugged
range, bordering a desert. The line of mountain and desert passes
southeast from Coalinga in a direct course for 30 miles, but immedi-
ately north of the town there is the reentrant angle of a valley and syn-
cline which separates the main range from one of the diagonally
transverse spurs and anticlines that are such conspicuous features of
the structure of the Coast Range. It is at the southeast end of this
anticline that the Oil City petroleum field has been developed.
The formations involved in the anticline embrace at least 1,000 to
2,000 feet of massive concretionary sandstones of Tejon (Eocene) age,
overlain by 800 to 1,000 feet of purple and gray shales, clays, thin
sandstones, and limestones, that have also been referred by some to
this period; 100 or 200 feet of clays and sandstones that may prove to
be Lower Miocene ; 200 feet of siliceous shales typical of the Monterey
(Upper Miocene); and, unconformable with these, a great thickness
of conglomerates, sandstones, and clays, recognized by their fossils to
be San Pablo (Middle Neocene). The conglomerates of the San Pablo
in this region contain pebbles of quartz, black chert, jasper, serpen-
tine, siliceous shale, and sandstone, the matrix being of the same
materials; the sandstones, which are coarse, are chiefly quartzose;
the clays are generally gypsiferous.
The Oil City field, as already suggested, is developed about the
southeastern terminus of one of the diagonally tranverse anticlinal
spurs that extend from the Coast Range into the valley of the San
Joaquin. The axis here dips rapidly to the southeast, and within 10
miles of the higher crest of the range evidence of the fold has com-
pletely disappeared beneath the valley deposits. The line of junc-
tion between mountain and desert on the northeast side of the fold
extends for 20 to 30 miles without conspicuous break. With the excep-
tion of severe crumpling in the immediate vicinity of the axis, accom-
panied perhaps by some faulting, and a comparatively gentle flexure
on the southern periphery of the uplift in the vicinity of Oil Creek,
the anticline appears to be unaffected by minor folds. The measures
exposed in the heart of the anticline are the massive Tejon sandstones.
Encircling these are the overlying shales, and these in turn are fol-
lowed by the heavy and resistant conglomerates and sands of the San
Pablo.
The oil-bearing horizons of this field are two: one, a sandstone in
the lower portion of the shales that are by some regarded as the upper
member of the Tejon; the other, the lower sandstones and conglomer-
308 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
ates of the San Pablo. It is estimated that approximately 1,500 feet
of measures separate the two horizons. Owing- to this distribution
there are two distinct areas of wells — an inner, in immediate prox-
imity to the axis of the anticline; and an outer, of more extended
area, encircling the point of the anticline in the San Pablo formation,
and extending well along the southwest side of the general fold. The
oil from the shales regarded as Tejon is of greenish color and varies
in gravity from 33° to 38° B. ; that from horizons in the San Pablo is
brownish black and of a gravity from 16° to 24° B., the higher in the
eastern portion of the field. The production from both horizons is
large. The depth of wells varies from 800 to 2,000 feet.
M'KITTRICK DISTRICT.
This district lies on the edge of the desert at the eastern base of the
Coast Range, about 50 miles west of Bakersfield. The railway station
is McKittrick. The Coast Range in the vicinity embraces a number
of parallel ridges, the highest constituting the eastern border of thJ
Carriso Plains. From this each succeeding ridge attains a lower
altitude, until the outermost line of hills is but a gentle elevation
above the general valley. The developed oil field in the region of
McKittrick lies along an interior ridge, separated from the outer ridge
by a valley 1.1 miles wide. The Length of this district is about 25
miles.
The formations involved in the occurrence of oil are the Monterey
and the San Pablo, an unconformity existing between the two. The
Monterey consists principally of siliceous shales, with their chalky,
earthy, or more argillaceous modifications. Gypsiferous clays, lime-
stones, and sandstones are but slightly developed, except in the north-
western portion of the field, where certain beds have the general
aspect of the Lower division of the Miocene. The siliceous shales
within a zone 200 or 300 feet in width extending for S or 10 miles
along the middle portion of the field, have, in a great degree, lost
their stratified nature and become tissile by reason of the severe crush-
ing to which they have been subjected in the sharp folding and fault-
ing that has here taken place. Along this line of faulting the shales
are of a chocolate brown, from the dried bitumen with which they
have been infiltrated.
The San Pablo, consisting of the conglomerates, sandstones, and
clays typical of it, is well develoj^ed, and the terrane is marked, as else-
where, by a deep deposit of dust wherever weathering has been car-
ried to an extreme. The lowest stratum of the formation exposed in
the field is a sandstone, conglomeratic in layers, the pebbles of which
are of granite, siliceous shale, quartzite, and occasionally a pyritic
rock that has been derived, perhaps, from some bed of much earlier
age. This sandstone and conglomerate is generally exposed in close
I eldridge.J PETROLEUM FIELDS OF CALIFORNIA. 309
proximity to the fault referred to above, and is also stained with bitu-
men.
The structure of the McKittrick district is that of a sharp anticline,
en echelon with adjacent anticlines of the range. Along its axis is
developed the fault mentioned, which locally is of the nature of an
overthrust, the siliceous shales of the Monterey west of the plane being
pushed up well over the sands, conglomerates, and clays of the San
Pablo. While this fracture and fold, along which most of the produ-
cing wells of the district are located, are the most important of the
region, other folds and faults exist in lines parallel with these, and at
either end of the district one or another of them may become the chief
fissure, j'et apparently, so far as is at present known, without especial
accumulation of petroleum. Of the overthrust nature of the main
fold interesting evidence exists in the material that is brought up by
the bailer in drilling — not only sands more or less saturated with oil,
but pebbles characteristic of the San Pablo. Conspicuous among the
latter are those of siliceous shale of the Monterey type, bearing foram-
iniferal remains, fish scales, and pholas borings. A noteworthy fea-
ture of the line of disturbance for several miles, both northwest and
southeast of McKittrick, also, are the dikes of sandstone richly impreg-
nated with bitumen. These vary in length from a few feet to a half
mile or more, and in width up to 10 or 15 feet; their depth, of course,
is unknown. Gash veins of high-grade asphalt also occur.
The productive oil wells of this district for its entire length lie
within a zone less than a quarter of a mile wide, and in places less
than 200 feet wide. Their depth varies from 200 to 1,500 feet, the
shallower holes being in the center of the field, opposite McKittrick.
The yield is from a few up to 700 barrels, the latter exceptional.
In gravity the oil varies between 11° and 17° B. While the narrow,
productive zone is persistent in the general directness of its trend —
about N. 60° W. — it is, nevertheless, somewhat undulating, according
as the axis of crumpling or faulting varies.
SUNSET DISTRICT.
This district lies in the southwest corner of the San Joaquin Valley,
along the eastern base of the San Rafael Range, about 35 miles in a
direct line southwest of Bakersfield, with which it is now connected
by a branch of the Atchison, Topeka and Santa Fe Railway. It. is
also distant from the McKittrick district about 25 miles, but recent
developments in the Midway field, the northwestern extension of the
Sunset, are gradually diminishing this gap. The Sunset field, like
those to the northwest, is developed in the lower foothills of the
Coast Range. The physical aspect of the region is that of moderately
rugged mountains, 3,000 to 4,000 feet in altitude, bordered by a desert.
The formations involved in the geology of the district include, in
the higher portions of the adjacent range, a great series of massive,
310 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213«ji
gray, concretionary sandstones and dark-colored shales, probably!
Tejon; on the slopes, local developments of gritty sands, brown and
yellow limestones, and gypsiferons clays, perhaps a lower division of
the Miocene, the upper division consisting of siliceous shales, typical
of the Monterey; in the low outer ridges, a successiou of conglomer
ates, sandstones, and clays, many hundred feet thick, the equivalent
of the San Pablo, of Middle Neocene age; and in the valley, Recent
gravels. Between the San Pablo and older formations — the horizon
of most importance from the petroleum point of view — there exists a
marked unconformity, the line of union as exposed lying now at one
horizon, now at another, in beds both above and below the break
in continuity. Just within the border of the younger formation the
development of the oil field has taken place, the wells drawing their
petroleum from one or more of the conglomerates and sandstones
adjacent to the plane of unconformity.
Structurally, the strata of the Sunset district, while thrown into an
anticline of great extent, present in detail a succession of folds, those
of greatest amplitude lying farthest within the mountains, the gen-
eral trend of all being about N. 50° W. Faults also exist, but none of
large displacement was detected within or near the oil-producing area
itself. The greatest crushing has been effected in the shales of the
Monterey, but along the desert edge the San Pablo also shows a
number of minor flexures, sonic developed en echelon, to which is
due the frequent offsets to be observed in the trend of the oil belt.
The general dip of the strata in the oil-yielding territory is northeast
or toward the valley. Its direction is, however, modified by the
flexures referred to, and by other and local variations in strike.
The wells of the Sunset district attain a depth of from 500 to 1,500
feet, and while there is a similarity in the oil sands, it is questionable
whether the same horizon is everywhere the productive zone, for the
San Pablo is deposited against a slope of the Miocene, from which it
might have drawn the petroleum into several beds abutting it at the
plane of unconformity. The wells in the Midway field are somewhat
deeper than those in the Sunset area proper, having been drilled
farther out on the slope of the anticline. The especial interest of
these wells is their position along the exterior of the anticline at a
very considerable distance from both axis and end, and in a locality
where the strike and dip are apparently maintained with great regu-
larity. The gravity of the oil in the Sunset district varies from 11° B.
in very shallow wells in the southeastern part of the field, to 17° or
18° B. in the deeper ones in the northwestern portion.
KERN RIVER FIELD.
The Kern River field, the most productive in California, lies about
3 miles north of Bakersfield, in Kern County, near the southeastern
extremity of the San Joaquin Valley. As at present developed it
cldridge.] PETROLEUM FIELDS OF CALIFORNIA. 311
occupies an area north of the river of approximately 12 square miles,
extending but a few hundred feet south of the stream. The general
trend of the oil-yielding zone is N. 40° W. , coincident with the strike
l' of the rocks. The field has excellent railway facilities, and an 8-inch
pipe line to Point Richmond, on San Francisco Bay, about 300 miles
distant, is under construction. In addition, there is a tank storage
capacity in the field of nearly 2,000,000 barrels. Refineries, also, are
nearing completion. The production of the field at the time of the
writer's visit was approximately 3,000 cars a month, actual shipments.
In topographic position the field lies at the edge of the uplands of
k the San Joaquin Valley, 12 miles from the base of the Sierras, and on
the southwest slope of the low ridge which separates Kern River
from its tributary, Poso Creek, about 7 miles to the north. Although
immediately adjacent to the fertile farms of the valley, the surface
aspect of the region itself is that of a desert hopelessly beyond recla-
mation. The strata underlying are soft and yielding to atmospheric
agents, and lie at but a shallow dip (SW.,), and as a result, erosion
has transformed the area for many miles into typical "bad lands."
South of the river a mesa country prevails.
The surface geology of the Kern River field is comparatively sim-
ple. The principal geologic formation of the region adjacent on the
east is determined by its fossils to be of Lower Miocene age. This
passes beneath the productive area, but whether upon more detailed
examination some of the surficial beds of this area will not be found
to be representative of the San Pablo is an open question. The strata
of the Lower Miocene include conglomerates, sandstones, and clays,
the several members of this series into which it may be differentiated
upon physical or other grounds arranging themselves in broad or nar-
row zones of outcrop according to the thickness to which they have
been developed and the angle of their always gentle dip. But while
the differentiation of horizons mentioned is comparatively distinct
over broad areas, there are local gradations from one zone to another
that frequently render it impossible to trace a maintenance of regu-
larity in the succession of strata. The entire series of beds, in fact,
has the appearance of a shore deposit along the granite range of the
Sierra, in which currents and waves have played their part in the dis-
tribution of materials, with the result that a sandstone at one point
may thicken or thin, and, according to conditions, be replaced by clay
or conglomerate, which, in their turn, again act in like manner. This
relation of the sediments one to another, which is evident from the
surface outcrops, is especially emphasized in the hundreds of wells
bored in the 12 square miles of the Kern River field. Even in the
wells of a single company, where the records have been uniformly
kept, this variation of sediments is a conspicuous feature, and it is
impossible for one to say from the record of one well what may be
expected in a hole to be drilled at a distance of 200, 400, or 600 feet
312 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
from it. A feature that is to be considered in this connection, how-
ever, is the fact that because of the lenticular form assumed by the
deposits of sands, gravel, and clays, a certain interlocking of sedi-
ments has taken place that has permitted a free circulation of oil
throughout the entire thickness of the oil-bearing zone, rendering it
remarkably productive.
The geologic structure of the entire region of which the Kern River
field is a part has not yet been worked out. There is a general south-
westerly dip of the Miocene beds from the Sierra granites outward,
and there is abundant evidence also of subordinate folds, the axes of
which lie more or less diagonal to that of the Sierra uplift. It is on
the southwestern slope of one of the anticlines of this series that the
oil field has been developed. The axial trend of this fold is approxi-
mately N. 40° W., with Local variation to N. G0° or 70° W. With the
rarest and most local exceptions, the dip is southwest, usually under
5° and often but 2° or 3°; and in an examination of the Lower Mio-
cene beds from the immediate vicinity of the granite outward there
was found at no point a dip in excess of 10°. Along the line of the
granite, however, the dip maybe considerably steeper, indicating the
extent to which the Tertiaries have been involved in the general
uplift of the main range. The axis of the Kern River anticline
appeal's to lie in the valley of Poso Creek, but the minor undulations
are so numerous that without detailed examination it is hazardous
to say just where the center of the arch is situated.
A study of the well records of this field points to the existence of a
general body of sands and gravels from the surface to a varying
depth up to 200 feet. Beneath this there is usually a stratum of blue
clay, also varying in thickness from a few feet up to 100 feet. This
clay is impermeable to the waters which nearly everywhere exist in
the sands above. Below 1 lie clay in all wells is an alternation of sand
and clay without regularity and varying in their relative thicknesses
from point to point. These sands constitute the oil reservoir of the
field, and as high as 400 or 500 feet, of them have been encountered
in a single well. In a great many wells 200 or 300 feet of oil-bearing
sand are found. Below the oil sands is another thin, blue clay, in
which the casings are, as a rule, landed. Occasionally a well has
perforated this, penetrating a water-bearing sand beneath, and in one
or two instances holes have been carried to still greater depths, pene-
trating a second clay underlying the oil sands, and finally passing
into a mass of sand and gravel which yields an enormous amount of
water. Many of the wells of this field at first flow, but sooner or
later all require pumping. The production is from light up to 600
barrels a day, according to the age of the well, its condition, and
the amQunt of sand upon which the well has to draw. The gravity of
the oil varies from 13° to 17° B., the lighter being found in the
western portion of the territory. The color of the oil is black.
)l
Ldridge.] PETROLEUM FIELDS OF CALIFORNIA. 313
LA GRACIOSA DISTRICT.
This district lies in La Graciosa Hills, 10 miles south of Santa
Maria, in the northwestern part of Santa Barbara Count}- . The hills
attain an altitude of 500 or 600 feet above sea level, and 1heir trend
is northwest-southeast, coincident with the structural development of
the country. Their surface aspect is that of grassy pasture lands or
of areas more or less densely covered with the live oaks peculiar to
the Pacific coast. The region is rendered accessible by a line of rail-
way to Santa Maria and San Luis Obispo.
The geology of the region embraces an underlying series of folded
Monterey shale, of both the soft and more organic material and that
which is hard and siliceous, the former predominating. So far as
observed by the writer, this series of beds is not exposed at any
point in its entirety. Overlying the Monterey unconformably is a
heavy and extensive deposit of Pliocene sands, grits, and conglom-
erates. The composition of these is chiefly quartzose, although there
is a mingling of other debris derived from the underlying shales and
from the granite and eruptives of more or less distant localities.
The full thickness of the Pliocene deposits is undetermined.
The structure of La Graciosa Hills is that of an anticline, the axis
of which has a general trend of N. 55° W. The Monterey shales,
which occupy its heart and are exposed over considerable areas, are
greatly contorted, but the younger sands of the Pliocene, where
mantling the older formation, dip to the northeast and southwest
from but 2° to 25°, according to their position on the flanks of the
fold. A marked unconformity exists between the Pliocene and
Miocene deposits, and it is impossible to suggest the surface con-
figuration of the sea floor upon which the younger of the two forma-
tions was laid down.
The developments in the fall of 1902 were chiefly confined to the
Carreaga ranch, on the southwestern slope of the anticline and hills,
but drilling was being prosecuted at a number of points west of the
producing area. On the Carreaga ranch the wells start in the Plio-
cene conglomerates and sandstones, passing into shale below, and
thence to the oil sands. Whether the shale was of the Monterey or
not is a question for future determination.. Difficulty will attend its
solution because of the uncertainty of measurements by reason of the
uneven surface attendant upon the unconformity existing between
the siliceous shales and the younger sands. Texture, however,
may aid,
The wells of this territory are large producers and the oil is of high
gravity.
SUMMERLAND FIELD.
This oil field extends along the Pacific shore for nearly a mile in
front of the small village of Summerland, 5 miles east of Santa Bar-
314 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213. ' L
li
bara. The wells are located on the bluffs, the shore, and upon wharves *
extending into the sea for nearly a quarter of a mile. The physical
aspect of the country is that of an undulating but highly cultivated |
terrace, 3 or 4 miles wide, lying between the sea and the lofty and"
abrupt range of the Santa Ynez Mountains, which parallels the whole f
coast of Santa Barbara County.
The formations of the region are the equivalents of the great red
sandstone series of the Sespe Canyon, 50 miles to the east; a series of
rusty sandstones and shales, with their interbedded, concretionary
limestones overlying the foregoing; siliceous and argillaceous shales
of Monterey type; a succession of conglomerates, sandstones, and
clays believed to be the equivalent of the San Pablo, and from 100 to
200 feet of Quaternary sands and gravels. An unconformity is evi-
dent between the Quaternary and the San Pablo and between this
latter formation and the Monterey.
The structure of the region has not been entirely worked out, but
there exists an anticline with axis exposed in the red beds along a line
midway between ocean and mountain base. North of the axis there
is, for a distance, apparently the same succession of strata as in the
Sespe region ; that is, the red beds are overlain by a series of rusty
sandstones, shales, and limestones. Beyond these, however, along
the higher mountain slopes, the present examination did not extendi.
South of the anticlinal axis the red beds, with a dip southward of
from 45° to 80°, are succeeded by shales of Monterey type, and these,
in the immediate vicinity of the shore, by the probable equivalent of
the San Pablo. The Quaternary is exposed in the ocean bluffs, and
here and there overlaps the older formations far toward the moun-
tains. From the difference in the succession of the formations south
and north of the anticlinal axis it is possible that an important fault-
extends along the bench lands of this portion of the ocean's front, the
throw of which can not be less than 4,000 or 5,000 feet. An alterna-
tive of this fault may be an unconformity between the siliceous shales
of the Monterey and the red beds of the Sespe formation.
The Summerland oil field is developed in strata having a southerly
to southwesterly dip of from 30° to 90°. It lies at a distance of approx-
imately 1 mile from the axis of the anticline. The source of the
oil is in one or more sands of the formation believed to be the equiv-
alent of the San Pablo, at a distance not far from its line of union
with the underlying Monterey. The well records in the main point
to a body of oil sand from 80 to 120 feet below the derrick floor, and
to another 40 or 50 feet below this, but many of the wells extend to
depths of 400 or 500 feet. The oil throughout the field is mixed with
a considerable amount of water, which is probably due to careless
methods in drilling, although it may be from the shallow depths of
the wells that sea water has penetrated to the productive beds. The
gravity of the oil in the upper and lower sands is said to be, approx-
luridge] PETROLEUM FIELDS OF CALIFORNIA. 315
inately, 10° and 14° B., respectively. The yield of the Summerland
veils averages a barrel and a half to two barrels a day, although
>ccasionally a well is found that for a while has a yield of 10 or 15
parrels, but such wells are the exceptions. The district has been
productive for several years, and the comparatively large original
field of the wells has now been reduced to a minimum.
SANTA CLARA VALLEY.
The valley of the Santa Clara is of structural development, modified
by erosion. It heads in the San Gabriel Rauge and in the mountains
bo the north connecting this with other portions of the Coast Range
and with the Sierras, and, after a westerly course of 75 to 100 miles,
enters the Pacific a little south of the town of Ventura. The valley
is given over to agriculture, but the mountains on either side are the
Loci of many important oil fields.
REGION NORTH OF SANTA CLARA RIVER.
The mass of rugged mountains north of the Santa Clara Valley,
forming the watershed between it and the great Central Valley of
California, represents the convergence of the several ranges which to
the northwest maintain a conspicuous individuality. Pine Mountain,
8,826 feet in altitude, is their culminating point. The area thus
occupied is a part of that recently set aside by the United States
Government to be known as the Pine Mountain and Zaca Lake
Forest Reserve. It is accessible only by trail, and is almost wholty
uninhabited. The southern edge of this great range is one of the
important oil fields of the Pacific coast.
The geologic structure of the region as a whole has never been
determined, but, in the present investigation, that along the edge of
the Santa Clara Valley was in part deciphered. It is probable that
the converging ranges have each their own structural representative
in this mountain mass, of which that studied is but a single member —
the eastward continuation, perhaps, of the Santa Ynez Range.
The formations involved in the composition of the oil fields and their
contiguous territory embrace several thousand feet of dark-gray
quartzites and interbedded shales, which are believed to be Eocene.
Overlying these are from 1,000 to 2,000 feet of red sandstones, con-
glomerates, and shales, the last in the minority. The age of these,
also, may prove to be Eocene. From their remarkable development
on the Lower Sespe River they are commonly designated by the name
of this stream. Above the red beds is a succession of 200 or 300 feet
of brown, rusty sandstones, followed by 1,000 or 2,000 feet of gray
and purple shales, with thin, interbedded, fossiliferous limestones
containing Lower Miocene forms. Succeeding the shales is a promi-
nent, cliff-forming, yellowish-white, concretionary sandstone 200 or
316 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
300 feet thick, followed by other shales which are hard, very siliceous,
and light gray or white. Overlying these is a second sandstone, |
somewhat similar to the first, but less concretionary, and this again
is overlain by other shales siliceous in tendency, but generally more
earthy and friable, and of a brownish color. The correlation of this
series in its entirety is in doubt, but the lower, highly siliceous shales ! i
are unquestionably of the Monterey type, while the sandstones and
the associated shales may also prove to be of the same formation.
Unconformable upon the foregoing rest several thousand feet of con-
glomerates, sandstones, and clays, which carry fossils that identify
the beds as of the San Pablo horizon in the Middle Neocene. Youngest
of all are some late Pliocene or Pleistocene conglomerates along the
slopes of the Santa Clara Valley.
The structure of the region is that of an anticline of very consid-
erable proportions, modified by subordinate folds and faults of the
utmost intricacy. Its axis has a somewhat irregular trend, varying
from N. 70° W. to N. 80° E., the principal curvature occurring in
the hills opposite the town of Pirn. The heart of the anticline lies
in Topa Topa Mountain and is occupied by the series of Eocene
quartzites and shales. Around these circle successively the Sespe
red beds, the Lower Miocene shales, the Monterey, and the equiva-
lents of the San Pablo, the last occupying vast areas extending from
15 to 30 miles or more east of the heart of the fold. On the north the
anticline is limited by other folds of equal importance, On the south
the flexure is modified by a succession of sharp folds of greater or
less extent, and by faulting, an especially important line of fracture
passing east and west in front of San Cayetano Mountain, extending
westward into the Ojai Valley, and eastward, perhaps, crossing the
Santa Clara Valley. Numerous branches are given off from this
fracture, particularly toward the west.
It is in such an assemblage of strata, with the intricate folding
to which they have been subjected, that the oil wells of the region
under discussion occur. In horizon the oil is drawn from the lower,
middle, and upper portions of the Sespe red beds, from the rusty
series at the base of the Lower Miocene, and from sandy measures in
the overlying shales; from the great sandstones which succeed and
are associated with the shales of Monterey type; and, finally, from
the equivalents of the San Pablo beds themselves. In addition, oil
is known to occur in the Eocene quartzites forming the heart of the
anticline. Fifteen thousand feet of strata, therefore, yield petroleum
at one point or another in this field. The distribution of the devel-
oped oil areas is either in a broad sweep about the axis of the main
anticline itself, in close proximity to the axes of some of the subor-
dinate folds, or along one or more of the great fault lines of the terri-
tory, such, for instance, as that south of the San Cayetano Mountain
and extending westward through the Silverthread district into the
eldripge] PETROLEUM FIELDS' OF CALIFORNIA. 317
Ojai Valley. The wells of this field vary in depth from 1,000 to 2,000
feet. The oil is said to have a minimum gravity of about 12° B.,
and a maximum of about 25° B. The yield of old wells varies from 1
i to 20 or 30 barrels a day, though that of new ones rises considerably
above this.
REGION SOUTH OF SANTA CLARA RIVER.
On the south of the Santa Clara Valley, separating it from that of
the Simi, are the Santa Susana Mountains and their westward exten-
sion, Oak Ridge. The former of these is in direct continuation also
with the San Gabriel Range, farther to the east. This linear series
of ridges in its entirety may be regarded as a unit both topographic-
ally and structurally. The San Gabriel Range has an altitude of
over 5,000 feet, the Santa Susana Mountains of nearly 4,000 feet, and
Oak Ridge rises a little above 3,000 feet. The northern face of the
uplift is particularly rugged.
The formations entering into the composition of the Santa Susana
Mountains and Oak Ridge are as follows: At the base, heavy-bedded
yellow sandstones, here and there pebble-bearing; overlying these, in
their most differentiated form, are from 300 to 500 feet of conspicu-
ously banded red and gray arenaceous clays, clayey sandstones, and
grits; above this, a yellow and gray sandstone, vaiyingly prominent;
still higher, from 400 to (500 feet of alternating gray and chocolate-
brown shales, sandstones, and thin fossiliferous limestones. These
are followed by from 200 to 500 or more feet of chalky and siliceous
shales of the Monterey type, and these, again,. unconformably, by a
great mass of heavy, coarse, granitic sands and conglomerates. Of
the foregoing beds the last may be the equivalent of the San Pablo,
while the portion underlying the siliceous shale is, in part, perhaps
wholly, of the Lower Miocene, fossils of this age occurring a short
distance above the banded red and gray series. Correlation, how-
ever, of this series of beds with those north of the Santa Clara Valley
has only in part been possible. The San Gabriel Range is a crystal-
line complex.
While the Santa Susana Mountains and Oak Ridge may be regarded
as a structural unit, there are, nevertheless, within the limits of the
uplift many anticlinal flexures, at least four of which derive especial
importance from being the loci of highly productive oil areas. Of
these anticlines one extends from the western end of Oak Ridge for
fully three-quarters of its length, the axis lying in the lower slopes
bordering the Santa Clara Valley. The second, third, and fourth anti-
clines, instead of paralleling the general ridge, lie diagonally trans-
verse to it and en echelon with one another. The western of these
extends along the easterly fourth of Oak Ridge and crosses the divide
in the gap between it and the Santa Susana Mountains; the middle
anticline follows diagonally the northern face of the Santa Susana
Mountains, crossing the divide a mile or two west of the low point
318 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
between them and the San Gabriel Range ; the eastern flexure conforms
to the western extremity of this latter range, its axis, however, pass-
in «• into the lower slopes of the Santa Susana Mountains about a mile
north of the middle anticline. In addition to the foregoing are sev-
eral intermediate flexures of minor importance. Faults, also, are
present, the most prominent region of fracture and general dis-
turbance being that of the Torrey wells, opposite the town of Piru. It
is noteworthy that the line of this disturbance is in the direct trend of
one to the north of the Santa Clara that may prove to be connected
with the San Cayetano fault.
The productive oil wells of the Santa Susana Mountains and Oak
Ridge lie in proximity to the axes of the anticlines or to the zones of
crushing described. The horizons from which the oil is derived
include one several hundred feet below the lowermost sandstones
exposed in Oak Ridge; another, perhaps these sandstones themselves;
a third, some of the sands in the brown and gray banded shales; and
a fourth, possibly the lower beds of the probable equivalent of the
San Pablo formation. The depth of the wells varies from 1,000 to
2,000 feet, according to location and the strata pierced. Their yield
has been much greater than al present, except in instances where the
territory is comparatively new. The gravity of the oil varies from
14° to 40° B., the former in the eastern portion of the field, the latter
in certain of the wells in front of the Santa Susana Range and Oak
Ridge.
I, OS ANGELES FIELD.
Los Angeles occupies an area about 8 miles square, the greater por-
tion lying west of the Los Angeles River at its debouchement from
the low hills which to the west pass gradually into the Santa Monica
Range and to the east into the San Rafael Hills and the Verdugo
Mountains. The Elysian Park Hills north of the city attain an alti-
tude of about 750 feet above sea level, about 500 feet above the
city itself. Their trend is northwest-southeast, their southwestern
slope gentle and extending well within the city limits, their north-
eastern slope abrupt and paralleling the Los Angeles River. The
area of productive oil wells extends in a belt one-fourth of a mile wide
from a point near the river at the northern edge of town to the west-
ern limits of the city in the vicinity of Third street, a distance of
about 3| miles. Still farther to the west, 8 or 0 miles beyond the
municipal boundary, are a half dozen more wells that may prove to
be in an area structurally related to the Los Angeles field proper.
The formations involved in the geology of the oil field embrace a
series of heavy-bedded, quartzose, somewhat concretionary sandstones,
with thin, interbedded shale and an occasional calcareous layer, con-
stituting the main portion of the hills north of the city; overlying
these, at least 300 or 400 feet of siliceous shale of Monterey type,
and above this a succession of sandstones and sandy clays which
eldridge.] PETROLEUM FIELDS OF CALIFORNIA. 319
have generally the appearance of the Pliocene strata of the Pacific
coast, and some of which also carry fossils of this age. An uncon-
formity doubtless exists between the last formation and that under-
lying. Above all, here and there, are recent gravels.
The structure of the Los Angeles field is anticlinical, the axis of
the fold lying along the river valley above the city, its direction
approximately northwest-southeast. The extent and precise nature
of the anticline is undetermined, but the region of Los Angeles is
apparently near the eastern end of the fold as it appears in the lower,
concretionary sandstones, for the lines of stratification of these
sandstones and of the overlying shales are traceable into the hills
east of the river, where they turn northward, cross the Arroyo Seco
into the San Rafael Hills, and thence veer to the west. The dip
in the latter territory is northeast, the opposite of that in the same
formation southwest of the river. Locally the anticline is modified
by subordinate flexures, some of which are of important significance.
Faults also are present.
The Los Angeles oil field is developed in the strata believed to be
Pliocene, on the southern leg of the general anticline. The trend of
the productive belt, however, instead of conforming to the axis of
the main fold, follows the strike of the formations on the south of a
subordinate fold divergent from the main flexure, and hence has
assumed a direction closely approximating east and west. Evidence
of this subordinate flexure and of the syncline which separates it from
the main fold is to be found in the northwestern portion of the city.
The average dip of the strata adjacent to the oil belt is between 30°
and 50°, but local disturbances of the beds, sometimes marked, are
found here and there, and it may be that faulting, too, has played
its part in the accumulation of oil in the field.
The Los Angeles field was one of the earliest developed in Califor-
nia, and the lapse of time since the inception of drilling renders
almost futile present-day attempts to obtain reliable data concerning
the conditions of occurrence of the oil. There exist, however, the
reports of the California State mining bureau, in which the progress
of development has been well recorded by Mr. Watts. It is sufficient
here that the wells probably draw their oil from two, three, or more
horizons in the sands and arenaceous clays that overlie the siliceous
shales. The general depth of the wells is from 600 to 1,200 feet.
Their individual production is small compared with many in the great
fields of the State, and, moreover, they show a gradual decrease year
by year. This, however, has been partially compensated by the prod-
uct of new wells. The gravity of the Los Angeles oil varies between
11° and 18° B.
PUENTE HILLS.
The Puente Hills are a low east-west anticlinal ridge about 25 miles
long and of varying breadth, their western end lying i<> miles a lill Le
320 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
south of east from Los Angeles. The altitude of their highest point
is 1,655 feet above sea level. Their slopes are comparatively smooth
and well grassed, and in certain localities there are limited areas of
oaks. Tributaries of the San Gabriel drain them on the north, and
of the Santa Ana on the south, but for most of the year the stream
courses are dry.
The formations embrace sandstones, shales, and conglomerates,
which from present evidence are to be regarded as equivalents of the
Lower Miocene, Monterey, and San Pablo formations. The Lower
Miocene is represented by several hundred feet of yellow and gray
concretionary sandstones, with thin, interbedded layers of siliceous
shales of Monterey type. These sandstones have an enormous devel-
opment in the eastern half of the Puente Hills, and according to
report continue southeastward across the Santa Ana River into the
Santa Ana Range, where fossils have been found in them which
determined their horizon.
The interbedded shales of this series, while of the Monterey type,
arc hardly to be classed in this division of the Miocene, by reason of
their occurrence in the midst of sandstones which are known to carry
Lower Miocene fossils. On the other hand, in the western half of the
hills there are strongly developed siliceous shales that carry Monterey
fossils and are to be regarded of this age.
The third and youngest series of rocks in the Puente Hills, forming
a prominent terrane along their southern base, is referred, from its
fossils and its lithologic features, to the horizon of the San Pablo.
The formation here consists of several heavy conglomerates, sand-
stones, and argillaceous shales and clays. The sandstones and clays
break down and disintegrate to the same impalpable powder as do
those of the formation in the region of Sunset, McKittrick, and Coal-
inga. This formation rests unconformably upon those below.
The structure of the Puente Hills is that of an anticline modified
by numerous subordinate flexures, the axes having a general trend
of N. 65° W. The western half is greatly contracted in its width,
while the eastern half is correspondingly expanded. Faults, also,
have entered to an important degree into the structure of the hills,
especially along the southern slope. Of these, or of an excessively
sharp crumple accompanied by minor anticlinal flexures, an especial
instance is to be found in a line of disturbance that passes immedi-
ately north of the Santa Fe wells, crosses to Brea Canyon, and is, in
fact, traceable at intervals over the entire distance to the region of
the Whittier wells. The Santa Fe and Brea Canyon wells are close
to this line of disturbance ; perhaps, also, the wells east of Whittier.
The Puente wells, lying between the latter and those of Brea Canyon,
are situated at some distance from the fractured zone, yet are to be
found in an area of considerable crumpling immediately adjacent to
the axis of the main fold. The geology in the immediate vicinity of
eldridge.] PETROLEUM FIELDS OF CALIFORNIA. 321
the Santa, Fe, Brea Canyon, and Whittier wells is rendered still more
complex by the proximity of the line of unconformity between the
San Pablo and underlying formations.
The horizons believed to furnish petroleum in the Puente Hills are:
For the Brea Canyon wells and most of those lying, east of Whittier,
the sands of the San Pablo formation; for the Santa Fe, the strata of
uncertain horizon in the disturbed area at the base of the hills in
their vicinity, in part, at least, of the Miocene; for the Puente wells,
probably the more sandy horizons in the great body of shales consti-
tuting the heart of the main anticline in its more contracted part, the
precise horizon of which in the Miocene is somewhat indefinite.
The wells in the Puente Hills are of wonderful productiveness, the
yield of many rising above 200 barrels a day, and in instances ap-
proaching 1,000 barrels. As in the case of all fields, however, the
production falls off: in greater or less degree according to the life and
condition of the wells and the territory drained. The depth of the
wells is between 900 and 3,000 feet. The gravity of the oil varies
from about 15° to 33° B. In color, both the black and green varieties
exist.
The region is connected by pipe line and rail with the main railways
of the Santa Ana Valley.
SUMMARY.
From the facts established in the preliminary examination of the
oil fields of California it appears —
That the productive areas have been in every instance developed
in connection with anticlines, either in proximity to their axes, along
their flanks, or about their terminals.
That in several instances faults, or intense disturbances of the
strata, have accompanied the folding, causing along their lines inter-
stitial spaces in which petroleum could accumulate, and thus result-
ing in an increased supply and yield.
That there are at least ten or twelve horizons in the 20,000 feet or
more of strata from Eocene to Pliocene that carry oil in quantities of
economic value.
That the reservoirs are either conglomerates, sandstones, or the
arenaceous members of the great shale groups in the Miocene.
That oil derived from shales is generally lighter than that of which
sandstones and conglomerates are the source.
That the stratigraphic and structural conditions under which oil
occurs in the known fields are many times repeated elsewhere in the
Coast Range and the territory contiguous thereto, from which it may
be argued that additional fields will in turn be discovered; and that
this view is strengthened by small wells already drilled and by the
known distribution of petroleum as evidenced by its seepage.
That the supply is exhaustible.
Bull. 213—03 21
THE BOULDER, COLO., OIL FIELD.
By N. M. Fenneman.
INTRODUCTION.
For many years the rocks near Boulder have been popularly sup-
posed to contain petroleum. The basis of such rumors lay partly in
the strong bituminous odor of certain rocks and partly in certain
cases of seepage known as "oil springs." Reports based on the
former can be traced back to 1867, at which time the black Benton
shales were dug into in search of coal. Their evident bituminous
character led Mr. Joseph Wolff and others about ten years later
to attempt the formation of an oil company, with the intention of
drilling near the center of the present developed field. The proposed
location at that time was determined by going straight east from the
excavations in the upturned Benton of the foothills to a point on the
plains where it was supposed the same strata might be horizontal.
The project failed for lack of funds.
The oil springs which have been reported lie north of this area, the
one best known being on the Culver ranch on the north bank of the
Little Thompson, 17 miles north of Boulder and several miles east of
the foothills. Here, at the base of the heavy sandstone stratum in
the Pierre (mentioned below), a seepage of oil has been observed for
forty j^ears. Several similar but less-known occurrences are reported
from 5 to 10 miles north of Boulder.
In 1892 a well was drilled on Gunbarrel hill, 1 mile north of Boulder
Creek and 7 miles east of the foothills. Accounts of this well are
very conflicting. Sufficient encouragement seems to have been
obtained from this attempt to keep alive the idea that future efforts
in the vicinity would develop a producing field.
Upon the renewal of interest in 1001 the Boulder Oil Company was
organized through the efforts of Mr. Isaac Canfield and Mr Charles
Page. The McKenzie well was drilled by this company. This well
struck oil in January, 1902, since which time many companies have
been organized and the exploiting of the field has proceeded without
interruption.
The exact location of most wells has been determined by "bobbers."
Rumors ascribe to Hayden various utterances on the subject of oil,
322
fenneman] THE BOULDER, COLO., OIL FIELD. 323
and it is even claimed that he set stakes to mark the proper location
of wells. A part of Sheet XII of his published atlas has been freely
used as "Hayden's oil map," and the area of outcrop of his Colo-
rado formation (including the Pierre) has been largely advertised as
"Hayden's oil belt." The belief even exists among some investors
that his survey was made for the purpose of locating oil.
GENERAL GEOLOGY.
The Boulder oil held, so far as developed, has its center about 3
miles northeast of the city of Boulder, Colo. Most of the wells which
have attracted attention as producers lie in a north-south line a little
less than 3 miles east of the prominent Dakota hogback which marks
the eastern limit of the foothill belt.
Stratigraphy. — Practically the entire Mesozoic group is represented
in this district, and most of it is of interest in the study of the oil.
At the base are 2,000 feet of Red Beds of the foothills consisting largely
of coarse, red, feldspathic sandstones or conglomerates, upturned at
a high angle and forming a sharp and rugged ridge. The upper 400
feet are more argillaceous and vary more in color, from light-colored
shales to dark-colored, ocherous, red shales and sandstones. These
Red Beds rest upon the uneven surface of the pre- Cambrian and are
themselves practically free from fossils and carbonaceous matter.
They therefore form a definite base in which and below which it is
useless to look either for the accumulation of oil or for its sources.
All higher formations are associated in some way with indications
of petroleum at various places in the Rocky Mountains, and in this
connection will be mentioned below under the occurrence of the oil.
Overlying these Red Beds is the Morrison formation, consisting of
about 250 feet of clays and limestones, with argillaceous and calcare-
ous sandstones. These beds, like the upper ones of the Red Beds, are
easily eroded, and the line of their outcrop is marked by a continuous
valley. They are not notably fossiliferous in this immediate vicinity.
The Dakota sandstone (Upper Cretaceous) overlies the Morrison.
Its outcrop, forming the well-known Dakota hogback, is, next to the
crags of the red rocks, the most prominent feature of the foothill topog-
raphy. The Dakota is here a 350-foot stratum of gray sandstone, some-
times at the base conglomeratic and often at higher horizons quartzitic.
Its outcrop would, on the whole, indicate that the Dakota is here as
elsewhere a porous stratum, though its high dip toward the plains
soon carries it beyond the reach of the drill. Like the strata below
this is also poor in fossils.
In general conformable on the Dakota are the Benton shales,
dark and bituminous, with a thickness of 500 feet. Locally, as at
the north end of the field, these shales become dense black limestone.
Certain horizons are crowded with fossils, especially species of Ostrea
and Inoceramus.
324 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
Above these shales the Niobrara formation has at its base 20 to 30
feet of limestone, compact, brittle, and fossiliferous. The remaining
300 feet vary from calcareous shales to shaly limestones; they are
fossiliferous and bituminous, and certain beds, from a few inches to
a few feet in thickness, are almost solid masses of Ostrea shells.
The topmost beds are of a gritty, shaly limestone having a buff color.
Overlying these and prominent from their contrast in color are the
dark shales at the base of the Pierre. They are-spar ingly fossiliferous,
but contain much finely disseminated carbonaceous matter. The
Pierre has a total thickness in this vicinity of probably 7,000 feet.
The dark color belongs more particularly to the lower part, the
remainder being generally lighter and having, after weathering, a
characteristically greenish-drab tint.
While, as a whole, a remarkably uniform mass of shale, the Pierre
has occasional beds which are more or less sandy, the constitution of
these varying from clay shale to pure sand. Only One such sand-
stone attracts attention by its outcrop. This is a gritty bed lying
about 2,000 feet above the base. Three miles north of Boulder it is
about 100 feet thick, but it thickens rapidly toward the north. From
about 3 miles north of Boulder its outcrop is almost continuous for
many miles to the north. There has been considerable speculation
concerning the relation of this sandstone to the oil, but, as will be seen
below, the stratum has no special significance. The texture of the
Pierre will be mentioned more particularly in connection with the
subjects of drilling and the occurrence of the oil.
Structure. — All the strata are steeply upturned against the moun-
tains. The Red Beds immediately west of the oil fields dip toward
the plains at an angle of about 55°. Higher strata outcropping
farther to the east have successively greater dips until the Niobrara
is reached, which is about vertical. Eastward from this line there is
a rapidly diminishing dip, and within a very few miles the position
may be horizontal or even show local westward dips.
Minor folds almost certainly exist. In the absence of ledge-making
strata they can not be determined by outcrops and have no influence
on the topography. Excavations have, however, revealed occasional
dips which are plainly not a part of the general eastward inclination.
Also the data from one small group of wells, but 2^ miles from the
foothills, strongly indicate local folding with dips as high as 15° or
20°. Here again the data are so limited that the direction of the
folding is uncertain. If parallel to the mountains, it may be regarded
as attendant upon mountain making; if the minor folds trend east
and west, they are in harmony with the Boulder arch so far as that
existed. a Other indications of a compressive force acting north and
south are locally observable in the sinuous strike of the Niobrara
limestone.
"Eldridge, G. H., Mori. U. S. Geol. Survey Vol. XXVII, p. 110.
penneman.] THE BOULDEE, COLO., OIL FIELD. 325
Of faulting it can only be said that it is as yet undiscovered and
probably undiscoverable unless it affects the strong sandstone ledge
mentioned above. Faults abound, however, near by, as in the vicin-
ity of Marshall, where the stronger Laramie preserves at the surface
the records of displacements. The possibility of such dislocations
within the oil field demands consideration both in the explanation of
1 he occurrence of the oil and in the exploitation of the field.
DRILLING IN THE PIERRE.
With few exceptions the wells thus far put down have been drilled
in the Pierre. The exceptions are among the scattered wells to the
east, which are on the very similar Fox Hills or even on the Laramie.
These also traverse the Pierre for the greater part of their depths.
Rate of drilling and expense. — Drilling in this formation is com-
paratively easy and rapid. It is not uncommon to make 100 feet in a
day at considerable depths, and this is sometimes done without change
of bits. On the other hand, slow progress is made in certain beds.
The average expense of drilling a wed] under contract with respon-
sible parties is, at the present time, about 11.65 per foot for the first
2,000 feet. Below that depth the cost is greater. Under such con-
tracts the owner of the well furnishes casing.
Water. — Surface water is usually encountered at about 15 feet and
may be found in the first 100 or even the first 200 feet. Below the
surface the wells are commonly "dry;" that is to say, the seepage
into the well from the dense shales is so slow as to be of no signifi-
cance in drilling. In isolated cases deep water-bearing strata are
encountered, and such water is sometimes salt. At Lafayette, 11
miles east of the foothills, water is reported as spouting from 4 to 5
feet between the 10-inch drive pipe and the 8^-inch casing. This
water was struck at depths of from 400 to 700 feet and is still flowing
after a period of four months. Hot water was reported found at
nearly 2,800 feet about 12 miles north of Boulder. In one well the
water from this depth was distinctly briny. Other wells have yielded
salt water from much smaller depths. In one well now pumping the
oil is mixed with about 10 per cent of salt water, which was encoun-
tered just below the oil. A slight admixture is found in at least one
other well.
Many wells are cased only to the depth of the surface water.
Others require 1,000 or even 2,000 feet of casing. In general deep
casing is not for the purpose of shutting off water so much as to avoid
caving, which is common though not general. It has necessitated the
abandoning of several wells.
Reports of materials passed through. — By far the most common item
in reports is shale or "slate," occasionally varied as "clay" or "soap-
stone." Sand or sand rock is often reported. With a showing of oil
it is often called "oil sand," with no particular reference to correla-
326 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull, an
tion with the sands of other wells. The composition of these "sands"
is generally far from that which the name would suggest. They are
not generally distinguished from the shales in color, but contain vary-
ing proportions of siliceous grains. They are simply more arenaceous
beds in the great mass of shale. Individual beds have all possible
compositions between a good clay and a good silica sand, the latter
being very rare. The thickness of these sandy beds may reach sev-
eral hundred feet, but they are generally much thinner. In drilling,
such beds are distinguished from the shales by their greater hardness,
by the more rapid wear of the tools, and by the smaller amount of
suspension in the water of the bailer. The washed-out samples com-
monly appear under close examination as a collection of gritty shale
granules whose edges have been rounded under the drill. The better
grades show an admixture of quartz grains, and exceptional beds are
almost pure sand.
"Streaks" and "shells" are other terms used to indicate more than
usual hardness at certain horizons. In the outcrops of these shales
may frequently be detected hard beds a few inches or even several
feet in thickness. They are either very calcareous or stained with
iron oxide or both, and owe their superior hardness to concentration
of these substances. Such induration may affect the entire bed
equally, or may be concentrated into ellipsoidal concretions, which
may be more or less separated, so that there are all gradations between
the continuous hard plate and the isolated concretions. The word
"shell" is suggestive of the latter, as the word "streak" is of the
former, but in the reports the two words may be taken to be synony-
mous and alike indefinite. The comminuted fragments of these hard
masses are not easily suspended in the water of the bailer and (prob-
ably for this reason, as well as their superior hardness) are not infre-
quently reported as sand. On the other hand, many of the so-called
hard streaks are no doubt siliceous. The reports of "lime rock" are
probably to be traced to the same occurrences. Many concretions,
also, have been cracked, and the cracks subsequently filled with
calcite.
The use of data obtained. — In such a mass of slightly differentiated
shale the record of a well is somewhat monotonous and few have been
carefully kept. Moreover, since the distinction between the shale
and the so-called "sands" is merely one of degree, some drillers report
large numbers of sand strata where others would report all shale.
Under such circumstances a complete series of samples would seem
to be the best possible log book. It has been difficult to obtain these,
largely because of the same monotony which, to the superficial
observer, has made the keeping of records unprofitable. Neverthe-
less, records and samples taken under all possible circumstances have
been reduced to as much system as possible. For all important cor-
relations the data have been carefully sifted. Only such observations
fenneman ] THE BOULDEK, COLO., OIL FIELD. 327
have been employed as are least liable to error when made by the
driller- Such, for example, are the "showings" of gas and oil, the
occurrence of water-bearing strata, the character of such water,
whether fresh or salt, and the hardness of the strata, as revealed by
the frequency of the change of bits.
OCCURRENCE OF THE OIL.
TJie oil-bearing strata. — The beds from which the oil is obtained are
the highly variable sands or sand rock described above as varying
between clay shale and silica sand. Such beds may be met with at
any depth and there is no depth at which such rock is certain to be
found. Reports might indicate that it is slightly more abundant at
a depth approaching 2,000 feet, but this may be due to the sharper
lookout for sand as the well gets deeper. Not all of these strata con-
tain oil or gas; some of the most porous sands give no indication of
either.
The thickness of such beds may be anything up to 100 or 200 feet,
but a stratum ma}' yield oil or gas from a part of its thickness only.
Such strata are plainly not so homogeneous as would appear from the
bailings and are not porous sandstones. Except in an oil well they
would probably not be called sands at all. It is not uncommon to drill
many feet into such strata and then strike a showing of oil or gas
with no attendant change in the texture of the rock that can be
detected in the bailings.
The lateral extent of these "sands" is generally small and always
uncertain. Their outcrops are so few, so short, and so far apart as
to afford little clue to the continuity of any one bed. As revealed by
the drill, no one bed can thus far be definitely known to be more
than half a mile in extent. Even that is a liberal assumption, based
upon the encountering of sand at similar depths in all the wells
within a radius of 80 rods. In even the best instance of this kind the
texture of the sand varies from well to well, some having small quan-
tities of oil, while others are dry. Moreover, a considerable local dip
must be assumed in this case in order to correlate the sands of each
well in a single continuous stratum. Hence it can not yet be affirmed
with confidence that even in this case there is an uninterrupted sandy
stratum one-half mile in extent. On the other hand it may well be
that more discriminating reports would show continuity at many
places where it does not appear from the reports received.
The horizontal limitations of these sandy strata are in'obably best
accounted for upon the supposition that their composition and tex-
ture vary from place to place, and hence a sand stratum may grade
into a shale at no great distance. The supposition that the deposits
are in lenses of somewhat homogeneous character must also be
admitted as possible, though direct evidence of such stratification
is lacking. Such lenses should be readily recognized in a group of
828 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
wells. Variations in thickness doubtless accompany the variations
in material.
The number of such strata passed in one well varies greatly. The
drill may pierce several thousand feet of shale with little change in
character, or a single boring may traverse half a dozen arenaceous
strata, two or three of which may yield showings of oil or gas or both.
These more porous strata are generally well separated, one from
another, by the intervening compact shales. Oil may be found in
any one of such strata or may be absent from all. It may appear in
a lower while absent from a higher stratum, and seemingly the reverse
may be equally true. Showings of oil or gas may occur in relatively
dense beds while absent from porous sands near by.
The isolation of the porous beds is well illustrated by the occur-
rence of deep veins of water in some wells and their absence from
neighboring wells at similar depths, or the deeper waters of one well
may be salt and those of a near-b}7 well fresh.
The mutual independence of the several oil pockets is not empha-
sized by any great diversity in the character of the oils from the differ-
ent wells. With a few exceptions there is approximate uniformity, as
shown by standard physical tests. Considering the striking uniform-
ity of the great body of shales, this approximate uniformity is to be
expected. It is too early to tell to what extent the yield of one well
may be influenced by the pumping of adjacent wells.
Relation to folds. — 11 will be seen from the above that the accumu-
lation of oil is not yet seen to be related to folds in the strata. Anti-
clinal arches of impervious stata are unnecessary to farm receptacles
for oil and gas in so dense a rock as the Pierre shales. If such folds
exist they do not appear al Hie surface, and they can not be recognized
from well data until the same stratum can be identified in different
wells. This would require a degree of precision in observation and
reports not yet attained in this field. In the meantime the ever-
increasing closeness of the wells is making the correlation of data
more definite.
While there is as yet no evidence thai deformation of strata has
anything to do with forming receptacles for the oil, it is not yet cer-
tain that the distribution of oil is independent of folds. According
to the most plausible theories wre may suppose that the substance of
these oils was at a former time disseminated through lower rocks rich
in organic matter. The concentration of this widely disseminated
bituminous matter implies a movement through the rocks, perhaps
for long distances. Such movement is conditioned by the texture of
the rocks traversed. The permeability of rocks in the axial plane of
an anticline may differ materially from that in the axial plane of a
syncline. It is conceivable, therefore, that in a system of folds, how-
ever gentle, the upward movement would be affected both in velocity
and in direction by the position of the rocks to be traversed, whether
i-knneman.] THE BOULDER, COLO., OIL FIELD. 329
under an anticline, a syncline, or the limb of a fold. Oil might there-
fore accumulate along certain lines, not because of being trapped in
anticlinal arches, but because the products of the original decompo-
sition or li distillation" (or whatever the process may be conceived to
be) have been able to rise along certain lines and not along others.
Whatever the explanation finally adopted, it is a noteworthy fact
that the wells now pumping are, almost without exception, located on
a nearly straight line, whose trend is north and south, parallel to the
mountains. Should this line be found later to bear any relation to
stratigraphic deformation, that relation will doubtless become an
important element in future attempts to locate oil in this region. Such
folds or faults, if determined at all, must be detected largely in accu-
rately kept well records, because the rock disintegrates so readily as to
make exposures of dips in surface outcrops of rare occurrence. There
is no other way in which the same amount of work can yield results of
such great financial importance as by the keeping of careful and
minute daily records.
The distribution of oil in belts parallel to the mountains can not be
considered proved by the meager data thus far obtained ; and if proved,
it might be due to causes not connected with structural deformation. A
line parallel to the mountains was probably parallel to the shore line
of the Cretaceous sea in which the sediments were laid down. The
presence of oil might therefore be due to conditions of sedimentation
at a nearly uniform distance from the shore, either the pl^sical char-
acter of the sediments or the conditions favoring life. But these will
not be discussed here.
Shooting of wells. — All the wells pumped up to the close of the year
1902 have been shot. The amount of nitroglycerin used in these
shots has varied from 10 to 120 quarts. Dynamite charges have been
as large as 500 pounds, 70 per cent nitroglycerin. The effects of these
shots have not been uniformly favorable. The beneficial effects in a
few of the best wells have doubtless been responsible for most of the
later attempts. It is by no means certain as yet that this practice will
be universal in this field. At least one well has recently begun pump-
ing without being shot, and the owners have no immediate intention
of shooting. The fact that the flow of some wells has decreased since
the shooting will lead to greater caution, and it is to be hoped that
it will lead to a more careful study of the conditions present in each
well.
The beneficial or harmful effects of a shot must depend largely upon
the texture of the stratum yielding the oil, for it seems to be true that
some shales are compacted rather than shattered by the explosion.
For this reason, shooting is not practiced in the Florence field, which,
of all the older oil districts, the Boulder field most resembles. Owing
to the difference in texture of the various' beds yielding oil in the
Boulder field, it is but reasonable to expect that the same shot which
830 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 2ld
would prove beneficial to one well would be ruinous to another. On
this account, if on no other, the texture and composition of the oil
strata should b3 carefully studied by methods far more discriminat-
ing than the superficial ones now used.
A second reason for injurious effects from shooting lies in uncer-
tainty about the exact depth of the sand which it is intended to shat-
ter. Measurements of depths by steel tape are indeed becoming more
common, but in a considerable number of wells the depths of all for-
mations are known only by cable measurement. Even in wells but
recently sunk, it is not uncommon that the stated depths of impor-
tant sands are thus liable to errors of 25 to 50 feet.
The possible injuries from a shot at the wrong place may be readily
seen from the following considerations: Given a porous rock satu-
rated with oil which is under a certain pressure. This rock is now
pierced by the drill. The oil soon fills the hole and is pressed upward
for the sole reason that it has no outlet in any other direction, being
surrounded (as in this field) by impervious rocks. This well is now
shot in such a way as to rupture the impervious rocks which have
surrounded the oil sand. The oil may now leave the sand by other
openings beside the well and may thus be dissipated in other porous
beds and the well may be ruined. Such an effect may be produced
even by shooting at the proper depth if the charge employed be too
heavy. In one instance a well was shot at 740 feet with 500 pounds
of dynamite, 00 per cent nitroglycerine. The formation above the
sand was a uniform dense shale. A good quality of sandstone was
blown from the hole in chunks reaching a maximum of 14 pounds*
The shale was ruptured to the surface. Open cracks of an inch or
more extended for some rods from the well. Presumably also, cracks
reached a considerable depth below the sand which was to be shattered*
It can not be too carefully borne in mind that the one object in
shooting is to shatter the rock which carries the oil and that only.
With this object in view, it is plain that intelligent and discriminat-
ing shooting must depend upon information which the following
questions may suggest: Is the texture of the oil stratum such as to
give promise that it will be shattered rather than compacted? What
is the exact depth of its top (and bottom if drilled through)? How
much of a shot will the overlying rocks bear without giving other
outlets to the oil? This last question is one of great importance in
this field. It is needless to say that such questions can be answered
only by a carefully kept log and close study of samples, not only of
oil sands but of all strata in order to properly forecast their behavior
under the influence of a shot.
Sources of the oil. — The source of the oil is not yet determined
within narrow limits. Much of the lower part of the Pierre is black
with disseminated carbonaceous matter. The Niobrara below is simi-
larly bituminous, yielding a strong odor from its more fossiliferous
fenneman.J THE BOULDER, COLO., OIL FIELD. 331
beds. The same is true of the Benton, whose shales are character-
isticalty dark and whose bituminous odor is at least as well marked
as that of the Niobrara. The Dakota bears oil in Wyoming, and
asphalt oozes from its cracks at various places from Wyoming to
southwestern Colorado. Even the Morrison beds contain some oil, as
seen near the Florence field.
The strata thus enumerated have a combined thickness of from
5,000 to G,000 feet below the horizon of the lowest oil reached in the
Boulder field. Not all parts of this great thickness are equally prob-
able sources of the oil. The lower beds of the Pierre are usually
darker in color and richer in organic matter than those horizons
immediately below the Boulder oil. The best of the "oil springs"
also point to a source not higher than the principal sandstone stratum,
which is about 2,000 feet above the base of the Pierre. The Benton
and Niobrara are probably richer in oil than any higher strata, and
surely in this immediate locality far richer than anything below.
The more probable sources, therefore, lie between the top of the
Dakota and the middle of the Pierre, a thickness of strata probably
limited to 4,000 feet.
Of these 4,000 feet probably containing oil, from 400 to GOO feet of
the most bituminous beds (the Benton shales) lie below the compact
basal limestone of the Niobrara. This limestone, though less than 30
feet thick wherever quarried for lime west of the oil territory, is very
dense, and where unbroken must probably prohibit the accumulation
of oil above from sources below this horizon. That it is unbroken
beneath the oil field is by no means certain. Within 5 miles (the
vicinity of Marshall) faults abound, many of them having displace-
ments far greater than the thickness of the Niobrara basal limestone.
Pronounced rupturing of the strata is shown within 2 miles, by the
Valmont dike. Such faulting as that at Marshall could not be
detected on the outcrop of the homogeneous and easily weathered
Pierre shales.
The folding which is almost certainly present would easily joint or
brecciate the brittle Niobrara limestone to such an extent as to make
it no barrier to the accumulation of oil above from the carbonaceous
constituents of the beds below. For the present, therefore, the
Benton shales should be taken into account, along with the higher
strata, in the consideration of possible sources of oil in this locality.
PRODUCTION.
Since January 1, 1901, there have been built within 5 miles of the
McKenzie well about 120 derricks. At 82 of these, wells have been
drilled to depths varying from 200 or 300 to 3,400 feet. In addi-
tion to these, 13 scattered wells have been drilled at various distances
from the foothills, both north and south of Boulder from the Cache
la Poudre River on the north to Coal Creek on flic south. Of these
332 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bui.i,. 213.
82 wells within 5 miles of the McKenzie, 57 lie within a rectangle hav-
ing a length of 3 miles north and south and a width of 2 miles east
and west, comprising sees. 8, 9, 16, 17, 20, and 21, T. 1N,R. 70 \V~.
Outside of this rectangle but three pumps have yet been installed,
none of which are at work at the present writing. Within this rec-
tangle there have been installed in all 17 pumps, of which 13 arc at
work regularly. The records of shipment from the entire field to 1 lie
present represent substantially the products of these 13 pumped wells.
Shipments prior to December 15, 1902, aggregated 9,000 barrels.
At the present time the daily shipments are about 8,500 gallons, or
about 200 barrels of crude oil. A small margin may be added to
these figures representing the amount consumed at the wells for light
and occasional fuel and sold at the wells for similar purposes. A
small refinery has been erected, having a stated capacity of 70 barrels
a day, but not much oil lias yet been handled here.
The United Oil Company has laid its own pipe lines to all produc-
ing wells and has bought practically the entire product, which has
been shipped to its refineries at Florence, Colo. The price now paid
on six months' contract is $1 a barrel at the mouth of the well. As
may be inferred from the price, the oil is of high grade. It is a light
illuminating oil with paraffin base. A valuable residuum now sold
for fuel may in the future add materially to the price of the crude
product.
ASPHALT, OIL, AND GAS IN SOUTHWESTERN INDIANA.
By Myron L. Fuller.
INTRODUCTION.
During the field work in southwestern Indiana in 1902 two discov-
eries, one of asphalt and one of oil, resulted from the sinking of deep
wells. While up to the end of the year no important developments
had taken place, it is not impossible that the discoveries may lead to
such developments in the near future. In the following paragraphs
brief notices of the recent discoveries and a short discussion of the
geologic structure are given.
ASPHALT.
During the drilling of a well by the Interstate Gas and Oil Company
at Princeton, in 1902, a bed of asphalt several feet in thickness was
found somewhat over a hundred feet below the Petersburg coal, or
that which is mined three-fourths of a mile west of the well.
In this connection it may be of interest to note that a similar bed is
supposed to have been encountered in the old Hall well on the south-
west outskirts of the town, about a mile south of the new well, and
that in the mine to the west of the well a black substance, known as
liquid asphalt, seeps into the bottom of the mine at 450 feet to such
an extent that some of the rooms have been abandoned and closed.
It is said to enter through a nearly vertical "break," filled with clay.
OIL.
Probably the best showing of oil found in this portion of the Slate
was obtained near Birdseye, Dubois County, in the summer of 1902.
The first well was drilled by the Southern Indiana Oil Company, of
Evansville, Ind. Oil was found in what the drillers call the "Trenton
rock," at a depth of about 1,000 feet. The well is stated to have
afforded about 5 barrels a day, but no pumping for the market has yet
been done. Up to the end of 1902 three wells had been drilled, two of
which obtained oil. Early in March, 1903, a flowing well in sec. 3,
T. 3 S., R. 3 W., was reported to have been brought in by the Stand-
ard Oil Company, while another was about to be drilled in by the
Southern Indiana Oil Company. The Ohio Oil Company is also
operating in the field.
333
334 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.]
The producing formation was penetrated to a depth of only 30 feet.
The oil is described as a high-grade 42 per cent lubricating oil. Very
little gas was encountered, and no determinations of pressure or vol-
ume were made.
NATURAL GAS.
Some years ago a considerable pool of natural gas was struck in the
"Jumbo" gas well, near the Woolley coal mine, at Petersburg, but
although considerable deep drilling was done at various times about
Petersburg, Oakland City, Princeton, and other points in the region,
no commercial pools were developed. The "Jumbo " well, after flow-
ing for a time, ceased to produce, but has since been cleaned out and
now supplies the illumination for the town and furnishes the fuel for
several hundred gas stoves. It is said to show a rock pressure of 585
pounds. A new well was being drilled at Petersburg during the sum-
mer of 1002.
CONDITIONS FAVORABLE TO SUCCESS IN DRILLING FOR OIL OR
GAS.
While it is probable that similar if not greater pools may occur at
other points in this region, their position can not be predicted in
advance of drilling. The positions which are geologically the most
favorable for drilling are the low anticlinal swells and the areas along
the strike lines of the rocks just east of the points where their west-
ward dip changes from flat to steep. Maps showing, by means of
underground contours drawn on the Petersburg coal, the structure of
the rocks in Pike, Warrick, and parts of Vanderburg, Spencer, and
Dubois counties have been recently published by the United States
Geological Survey."
STRUCTURE.
The general strike of the beds in southwestern Indiana is nearly
north and south. Although there are many irregularities and even
reversals of the dip, the general inclination of the rocks is commonly
not far from due west. The amount of dip varies from 10 to 40 feet,
with perhaps an average of about 20 feet to the mile.
Among the more noticeable of the irregularities shown by the
structural contours of the published maps of the Ditney folio are the
shallow synclinal troughs near Littles, Ayrshire, Winslow, and near
the county line north of Scalesville, and the low anticlinal swells
northwest of Glezen, between Oakland City and the Patoka River,
south of Winslow, near Arcadia, and southwest of Boonville. The
crests of the swells afford, from a geologic standpoint, the most favor-
able locations for gas wells, while their flanks afford the most promis-
ing points for oil wells.
P
a Geologic Atlas U. S., folio 84, Ditney. Descriptions by M. L. Fuller and G. H. Ashley.
puller.] ASPHALT, OIL, AND GAS IN SOUTHWEST INDIANA. 335
The anticlinal swell northwest of Glezen is a broad, low swell, the
crest of which may be considered as starting near Clark and as pass-
ing sonthwestward about midway between Glezen and Rumble and
through the group of coal strippings at the head of Robinson Creek,
finally subsiding at a point a little to the east of Oatsville. The second
swell mentioned is first noticeable at a point about a mile south of
Winslow. The crest passes a mile south of Ayrshire and through
Sophia and Turkey Hill. It subsides before reaching Oakland City.
The swell near Arcadia appears to be a somewhat irregular dome, the
highest point of which is probably a little west of town. The axis of
the last of the swells mentioned as occurring southeast of Boonville is
apparently located a little over a mile south of the railroad at this
place, from which point it extends southeastward toward Midway. It
has, however, been traced only as far as the alluvial flats.
The change from flat to steep dips and vice versa are usually grad-
ual and do not admit of very exact location. In general the dips are
steeper east of a north-south line drawn through Oakland City, and
are flatter from this line westward to the vicinity of Francisco, where
they again appear to steepen. The minor irregularities, sometimes
characterized by dips as high as 5° or 10°, are likely to be of more
importance as regards the occurrence of oil and gas than some of the
broader features, but they do not usually extend for more than a few
hundred feet at the outside and their location can seldom be predicted.
STRUCTURAL WORK DURING 1901 AND 1902 IN THE EASTERN
OHIO OIL FIELDS.
By W. T. Griswold.
INTRODUCTION.
In the latter part of the field season of 1901 the writer undertook
the investigation of two important economie problems relating to the
accumulation of oil, the field work being continued during 1902. The
problems noted were, first, the determination of the degree of accu
racy with which a stratum at considerable depth can be plotted under
favorable conditions, viz, easily distinguished outcropping strata and
high degree of accurac}7 in topographic and geologic work, and, second,
the effect of geologic structure on the accumulation of oil and gas.
FACTORS CONTROLLING ACCUMULATION OF OIL.
Structure. — The theory that the accumulation of oil and gas is con-
trolled by the geologic structure of the porous strata in which it is
contained has been advanced by Prof. I. C. White, and discussed by
many leading geologists under the general designation of the anti-
clinal theory.
The anticlinal theory ascribes the accumulation of oil and gas in
pools of economic value to the influence of geologic structure. The
oil and gas are supposed originally to have been widely disseminated
throughout the sedimentary deposits in which they were formed, and
their segregation is thought to be due to the different specific gravi-
ties of the various fluids occurring in the rocks. If a porous stratum
contains gas, oil, and water, these fluids will arrange themselves
according to their specific gravities, and if this stratum is not hori
zontal the lighter fluids will be forced toward the higher part of the
stratum until their progress is stopped by change in structure or other
conditions. In this case an accumulation of gas and oil will be formed
that may be of sufficient quantity to be of economic value.
This theory is now generally accepted by leading geologists. Unfor-
tunately, however, only a small percentage of the men actually
engaged in the production of oil attach much value to any geologic
theory. This is probably owing to the fact that the method of repre-
senting geologic structure by contours has not been previously applied
336
griswold] STRUCTURAL WORK IN EASTERN OHIO OIL FIELDS. 337
to the oil-bearing strata, so that each oil operator might himself study
the structural conditions which have produced valuable oil pools in
the past. The many failures of those hunting for oil on the anti-
clinal theory have thrown discredit upon the ability of geologists to
assist in the location of productive territory. Most of these failures
have been due to lack of knowledge concerning the geologic structure
or to the absence of other conditions necessary for the accumulation
of oil. Although geologic structure is of primary importance, it is
only one of three or more conditions that must be fulfilled in order to
produce an oil pool of economic value.
Porosity of the sand. — The condition of the sand as to degree of
porosity and capability of holding a fluid is a factor of great impor-
tance, and One that, with the geologic structure, governs the accu-
mulation of oil. It is evident that when a sand is loose and composed
of large grains fluids may pass easily between the particles, and that
a much less slope or grade would cause salt water, oil, and gas to
accumulate in separate bodies than if the sand were fine and close
grained. The condition of the sand can in no way be determined
except by the sinking of a test well. , In many instances, within a dis-
tance of 600 feet from wells of large production from a good sand,
other test wells have found the sand hard and closely cemented and
incapable of holding fluids of any description.
Degree of saturation of sand and position of water line. — The sat-
urated condition of the porous stratum is another factor of primary
importance in the formation of a pool of oil, and one that has not been
given due prominence. The water-line theory, as advanced by the
writer, assumes that the tops of the anticlines often contain no liquid
upon which the oil may climb, so that, while the gas from its lesser
gravity may pass on to the very highest point of the stratum in which
it is contained, the oil will rise only so far as it has the water for a
supporting medium. Tfre height of the water line thus gives a line of
equal elevation along the strike of a stratum, which, when once deter-
mined by the drill, should be followed to keep on the line of oil-pro-
ducing territory. The belt of oil accumulation may be illustrated by
a comparison of it to the sand beach along the shore of the ocean,
where the sea represents the salt-water area, the upland the area of
dry rock, and the sand the belt of saturated oil stratum. This belt,
like the ocean beach, may be narrow or widen out over considerable
space, so that the saturated portion of the oil stratum may be wider or
narrower, forming what appears to be a line of separate pools. The
amount of saturation is different in different sands and also in ATarious
parts of the same sand. In a sand containing only small saturated
areas the oil accumulation may be low down in the syncline, with an
area reaching far above it that upon test would only produce dusters.
Each independent structural basin must be considered separately as
to the location of the water line. Great assistance would have been
Bull. 2113—03 22
338 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
given in the location of this line of complete saturation had the unsuc-
cessful test wells of the past been divided into two classes, as salt-
water wells and dusters, instead of calling them all dry holes, as has
generally been done.
The question of saturation does not assume the same prominence
when searching for gas, though had it been noted and reasoned
from, it would have saved many thousands of dollars expended in
searching for oil near large gas wells.
In territory where the anticlinal folds are entirely below the satu-
rated area the water-line theory is of no value, as the accumulations
of gas are in the anticlinal arches, with the oil immediately below.
Under this condition the crest of the anticline should be followed to
find productive territory and the extent of the gas accumulation
determined by test wells.
AREA SURVEYED.
The area selected for investigation in 1901 was the Cadiz quadran-
gle, an area containing about 240 square miles in Harrison and
Jefferson counties, Ohio, and lying east and norch of the town of
Cadiz. The surface forms a plateau, which has been dissected by the
streams to a depth of nearly 300 feet, exposing in outcrops six or
seven easily distinguished beds of limestone and coal. The geologic
section extends upward from near the base of the Conemaugh (Lower
Barren) Measures to about the middle of the Monongahela (Upper
Productive) Measures. The Pittsburg coal outcrops in the lowest
valleys in the southeast corner and tops the highest hills in the
northwest corner of the quadrangle.
Parallelism of strata. — As these beds are of sedimentary origin it is
evident that there must be a certain degree of parallelism between
the strata, hence a stratum lying 1,000 or 1,500 feet below the surface
may be platted by data obtained from deep. wells and from the out-
cropping strata with the same degree of accuracy as one but a couple
of hundred feet below. The distance between two prominent strata,
such as an outcropping coal at the surface and an oil sand below,
maybe increasing or decreasing. In the Cadiz quadrangle the dis-
tance from the top of the Pittsburg coal to the cap of the Berea grit
sand is 1,481 feet at tin' Bricker oil pool, 1,490 feet at Hopedale, 1,527
feet at Bloomfield, and 1,564 feet at Smithfield.
The rate of variation of the interval between two strata can be
determined only by actual boring tests. Over the Appalachian oil
fields such tests have been made in great numbers by the "wild cat"
wells searching for oil. There is hardly a portion of the country lying
within the now producing oil fields where the record of such a well
can not be obtained within a distance of 5 miles from a given point.
In extending the platting of substrata into entirely new territory
a rate of increase or decrease must be assumed, which introduces a
degree of uncertainty into the results.
GRiswoLD] STRUCTURAL WORK IN EASTERN OHIO OIL FIELDS. 33V)
METHOD OF CONSTRUCTING MAP OF THE OIL SAND.
Each outcrop was carefully located upon a topographic map previ-
ously made by the Geological Survey, and from the bench marks
established by the Survey a spirit-level line was run to each outcrop,
establishing its exact position above sea level. Then by adding to
or subtracting from the elevation of the outcrop an amount equal to
the vertical distance at that point between the bed leveled to and the
Pittsburg coal the elevation of the Pittsburg coal at that point was
determined. In this way the true altitude of the key horizon (in this
case the Pittsburg coal) was established at five or six hundred places
over the quadrangle. By connecting the points of equal elevation a
contour map of the key horizon was constructed. The position of
each oil well which had been drilled in the quadrangle was care
fully located upon the topographic sheet. Spirit-level lines were run
to the mouth of each well, establishing its elevation above sea. In
most cases the steel-tape measurement of the distance from mouth of
well to the Berea grit sand was obtained from those interested in the
wells. By comparing the elevation of the mouth of the well to the
contour map of the key horizon the distance from this horizon to the
cap of the Berea grit sand was determined in different portions of the
quadrangle. The distance was found to vary, increasing gradually
toward the southeast. At the position of each test well the vertical
distance between the Pittsburg coal and the Berea grit was marked
upon the map.
The positions of the different test wells were connected by straight
lines, and these lines were divided so that each subdivision repre-
sented the horizontal distance in which the vertical distance from the
Pittsburg coal to the Berea grit decreased 5 feet. The points of equi-
distance from coal to sand were then connected, and a drawing was
constructed, called the " convergence sheet." This shows by a series
of lines the points of equal distance between the Pittsburg coal and
the Berea grit. The convergence sheet was then placed over the plat
showing elevations of the key horizon, and it showed at once the
amount that should be subtracted from the elevation of the Pittsburg
coal to determine the elevation of the Berea sand at any point. The
elevation of the Berea sand at every point where it was determined
was then marked upon the map and the points of equal elevat ion
were again connected, resulting in a contour map of the oil-bearing
sand.
STRUCTURE OF BEREA GRIT.
The contour map of the Berea grit sand shows a system of parallel
folds in a northeast-southwest direction, crossed at nearly right angles
by a system of broader and less pronounced folds, which break up the
major structures into a series of elongated domes and canoe-shaped
basins very similar to those of western Pennsylvania, as delineated
by Mr. M. R. Campbell.
340 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
The most prominent feature is the main anticlinal arch, which
extends from near Cadiz in a northeasterly direction, passing just
cast of the town of Salem, where it attains its greatest height.
Thence it swings to a more easterly direction and rapidly falls away
before reaching Richmond. The corresponding syncline parallels
this fold on the western side, but it is interrupted by two cross anti-
clines, one near the line of the Pittsburg, Cincinnati, Chicago and
St. Louis Railroad, the other very nearly agreeing with the location
of the ridge road from East Springfield north toward Bergholz. It
thus forms a canoe-shaped basin, whose lowest point is but a short
distance east of the town of Jefferson. A part of another basin,
which extends almost due east and west, appears in the northeast cor-
ner of the quadrangle, its center line being very near the location of
a topographic feature known as Middle Ridge. To the east of the
main anticline the sand descends in terraces or steps to the eastern
limit of the quadrangle, the crests of the terraces extending in lines
parallel to the main anticlinal fold. Over this slope the intersection
of the cross folds moves I lie terrace toward the east. This causes the
steep slope below the terrace to have a southeast strike for a short
distance before again taking up a direction parallel to the major
folding.
No long and steep slopes exist in the quadrangle. The descent is
steepest on the face of the terraces, where it seldom amounts to 100
feet to the mile. This lack of decided slope for a considerable dis-
tance is unfavorable to the accumulation of a large pool of oil, since
no large area of oil-producing territory has been drained into a single
continuous reservoir.
OIL DEVELOPMENT.
All of the oil developments that existed at the time of survey are
represented upon the map in Bulletin No. 198 of the United States
Geological Survey — The Berea Grit Oil Sand in the Cadiz Quad-
rangle, Ohio. The valuable oil pools then known consisted of the
Bricker and Snyder on the eastern side of the main anticline, the
Jewett pool on its western side, and the Amsterdam pool at the head
of the canoe-shaped basin east of Jefferson.
TESTS AND DEVELOPMENT DURING THE YEAR 1902.
During the year 1902 a number of new wells were drilled within
the area mapped, with the object of extending the known productive
territory and in the hope of finding new pools.
With a view of determining the degree of accuracy with which the
contour map of the Berea grit sand had been made in the Cadiz quad-
rangle, and to learn if the future development of valuable territory
would follow the theoretical reasoning of the published bulletin, a
careful watch of the new work was kept during the last summer and
GUTKWoi.n J STRUCTURAL WORK IN EASTERN OHIO OIL FIELDS. 341
level lines carried to the mouth of each new well of which a record
could be obtained.
Piney Fork district. — In Bulletin No. 198 this locality is described
as follows:
To the west of Smithfield, on and near the Piney Fork of Short Creek, four test
wells have heen drilled. Well No. 182, on the farm of Alexander S. Thompson,
gave a fair show of oil. This well is shown on the map to be on a small terrace.
The other wells, Nos. 181, 183, and 240, were simply dry holes.
During- the last year the Sutherland Oil Company, of Chicago,
drilled two test wells in the Piney Fork district. The first well is on
the Finley farm in the middle of sec. 22, T. 8 N., R. 3 W., on the east
side of a small stream flowing into Piney Fork and just south of the
Updegraff-Smith field road. The map of the sand shows that the
Berea grit is 505 feet below sea level and that the well is located at
the foot of a rather steep slope. This latter condition would indicate
the probability of a salt-water area. The elevation of the mouth of
well is'984 feet above sea level, making, according to the map, a dis-
tance of 1,489 feet from well mouth to the Berea grit. The Berea grit
was actually found at a depth of 1,487 feet, and the well produced
salt water which rose 1,000 feet in the casing. The second test in this
locality by the same company was made on the Thompson farm, on
the east side of the creek and very near the northeast corner of sec.
29. The map shows the sand at this point to be 445 feet below sea
level, and the well seems to be on the terrace previously referred to.
The elevation of the mouth of the well is 1,012 feet above sea level;
therefore theoretically the distance from surface to the sand should be
1,457 feet. The sand was found at 1,469 feet, showing the map to be
in error 12 feet at this point. A showing of oil is reported from the
Berea grit, with a strong flow of gas and some oil from the Big Injun.
No further tests have been made in this locality.
In Bulletin No. 198 the following suggestions were made as to the
northern extension of producing territory along the main anticline:
North and northeast of the Snyder pool six wells have been sunk in the attempt
to find other pools "by an extension of the alignment of the Bricker and Snyder
pools, with uniformly unfavorable results. With the information shown on the
contour map these results might have been anticipated. It is here that the cross
anticline hreaks up the regular structure, and the terrace face is moved over to
the east of the town of Hopedale, where it again takes up its northeasterly direc-
tion and is, in fact, the extension of the Bricker and Snyder pool terrace. Two
test wells have heen drilled in the southeast end of this terrace. The first well.
No. 203, found a show of oil, and this led to the drilling of the second well, No.
204, with the intention of striking the sand fully 10 feet higher than in the first
well. This the drillers failed to do, finding the sand only 2 feet higher in the
second well than in the first. This slightly increased elevation caused an increase
in the amount of oil found. The well was put to pumping, resulting in from 1£
to 2 barrels a day.
Spellacy pool. — During the last summer Mr. Spellacy and partners
drilled a test well on the line between sees. 14 and 15, T. 10 N., R. 4 W.,
342 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [Bull. 219.
in about the middle of the sections and about 1,500 feet north of the
Cadiz-Hoped ale road. The sand is here represented by the map to be
270 feet below sea level, and the location of the well is in the direct exten-
sion of the center of the Snyder pool. The elevation of the mouth of
the well is 1,157 feet, making, according to the map, 1,427 feet from
the mouth of the well to the Berea grit. The record by actual drilling
gives 1,431 feet. This well produced 8 barrels a day for the first thirty
days. Another well was drilled a short distance to the southwest,
resulting in a producer, but smaller than No. 1. The next well drilled
is to the east of No. 1 and about GOO feet distant. It came in a pro-
ducer good for 20 barrels a day.
This new development, known as the Spellacy pool, caused new
testing to decide whether the producing territory would keep to the
northeast or make a sharp turn to the southeast, as shown by the
contours of the geologic structure map. Testing was done in both
directions. Messrs. Scott, Ripley, and others located a well on the
Grant Bowles farm in the eastern part of sec. 13, T. 10 N., R. 4 W.,
just south of the Hopedale-Falks station road. At this point the sand
is represented by the map to be 256 feet below sea level. The elevation
of the well mouth is 1,203 feet, making an estimated depth of well of
1,459 feet. The elevation of the sand at the location of this well was
shown by the map to be at the same elevation as the top limits of
productive territories in the Snyder pool. This would indicate a
small well or total absence of oil. The sand was found by drilling at
1,465 feet, and the result is a perfectly dry hole.
The Sutherland Oil Company, after careful study of the Berea grit
map, decided to try a test well in the north part of sec. 8, three-
quarters of a mile southeast from the Spellacy pool. The location
selected is on the J. R. Skelley farm, one-quarter of a mile southwest
of the limits of the town of Hopedale, south of the small stream and
north of the 270-foot contour, as represented on the map of the sand.
This contour passes through the most productive area of the Spellacy
and Snyder pools. The elevation of the well mouth is 1,130 feet, and
sand is represented by the map to be 2G8 feet below sea level, making
an estimated depth of well of 1,398 feet. The sand was found at
1,407 feet, and a small producing well was obtained. A second well
was at once put down in a line with the first well and the Spellacy
pool. The elevation and record of well were not obtained, but it has
come in a producer.
Hopedale development. — A new development entirely independent
of the Spellacy pool, and due to the following suggestion quoted from
page 23 of Bulletin No. 198, was undertaken to the east of Hopedale
by the Welch Oil Company:
From the structure and indications of test wells already drilled, a very favor-
able line for finding oil seems to exist in a northeasterly direction from the south-
east quarter of sec. 3, toward the town of Unionport.
IftiswOLD.] STRUCTURAL WORK IN EASTERN OHIO OIL FIELDS. 343
The first location of a test well was made on the Allison farm, 1,200
feet south of the Hopedale-Bloorn field road and 1,000 feet east of
the Lake Erie, Alliance and Wheeling Railroad. The sand is rep-
resented by the map to be 270 feet below sea level. The elevation of
well mouth is 1,229 feet, making an estimated depth of well of 1,499
feet. The sand was found at 1,504 feet. The well is a small oil pro-
ducer, with large amounts of salt water. In order to strike the sand
above the limit of salt water, a well was drilled 500 feet north of the
road just east of the town of Ilopedale, on the farm of Mr. William
Stringer. The location, as shown by the map, is at the highest point
of the anticlinal nose, which extends south at the town of Hopedale.
The sand is represented to be 242 feet below sea level, and the eleva-
tion of the mouth of the well is 1,228 feet, making an estimated dis-
tance to the sand of 1,470 feet. The sand was found at 1,176 feet.
The result was a gas well with a pressure of about 400 pounds to the
square inch. It now seems very probable that there is oil-producing
territory between the Stringer gas well and the Allison small oil well.
Test welled Unionport. — The same company also drilled a "wild-
cat" test well in sec. 35, T. 9 N., R. 3 W,, south of the railroad, and
very near the eastern line of the section, on the farm of Mr. Lewis,
west of the town of Unionport. The sand is here represented by the
map to be 245 feet below sea level. The elevation of the well mouth
is 972 feet above sea, making an estimated depth to the sand of 1,217
feet. The sand was found by the drill at 1,220 feet. The well
resulted in a perfectly dry hole, with a hard and close sand.
Eastern Ohio Oil Company's test wells. — During the past year the
Eastern Ohio Oil Company, of Chicago, drilled a number of test wells
in the area southeast of Cadiz, with unfavorable results. No records
of these wells have been obtained, and for that reason the expense of
leveling to the mouths of the wells was not incurred.
Amsterdam pool. — Little new development has been undertaken in
the north half of the area covered by the Cadiz quadrangle. The
following reference to the Amsterdam pool is taken from page 24 of
Bulletin No. 198:
The accumulation from the canoe-shaped basin on the west side of the main
anticline has been discovered in part at Amsterdam.
The sand at the Amsterdam well is of such a poor quality that it probably
would have been reported as all lime had it not been oil producing. The wells
are small, but will probably improve when areas of better sand are found. The
limits of this field have been determined across the dip of the sand by a salt-water
well. No. 205, and a gas well in sec. 19, not located on the map. The extensions
along the strike are as yet not defined by test wells. The indications are that the
extensions will be to the southwest in a diagonal line through sec. 80, and to the
east in an almost due east line through the south half of sec. 7.
The pool has during 1902 been slightly extended to the southwest
by a well on the McGarey farm in sec. 30, which was located near the
344 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
house of Mr. McGarey on the road from Yellow Creek to Kilgore.
This well, although small, will produce a paying quantity of oil.
CONCLUSIONS FROM THE RESULTS OBTAINED.
The results of the developments during the last year seem to afford
strong evidence in support of the theories advocated in Bulletin
No. 198.
Over the area tested the map has proved to be of such accuracy
that it may be relied upon within a limit of the contour interval.
This should make the map of great value to the oil producer as a
guide to the location of new wells.
It is believed that a map of the different oil sands can be made over
the Appalachian oil field by careful geologic work and the united
assistance of the oil operators in furnishing full and reliable well
records that will be of immense value to the oil industry.
The result of the extension of the Snyder pool in a line exactly
agreeing with the contour line representing the Berea grit furnishes
strong evidence in favor of the water-line theory.
USE OF A MAP OF AN OIL SAND IN UNPROSPECTED TERRI-
TORIES.
The use of a contour map of an oil sand to locate new pools in
unprospected territory will materially aid the prospector, but can not
be absolutely relied upon, as the other conditions necessary for an
accumulation can only be learned by actual tests.
In the north part of the Cadiz quadrangle is an east- west syncline
with a decided rise on its north sid<\ Here is a favorable structure
for an accumulation of oil and gas, though the exact point at which
the oil would be found would be hard to select.
In making a systematic search for productive territory in this
neighborhood the first test well should be drilled in the southeast
corner of sec. 25, T. 11 N., R. .'), with a view of determining the condi-
tion of the sand, expecting if a favorable sand without oil is found to
obtain salt water. If no good sand is found, the result is a complete
failure and no information of value is gained. If, however, a good
sand containing salt water is found, a move to the northwest equal to
a distance that will cover two or three contours on the map of the
sand would be advisable, and so on until oil or dry sand is found.
If moves not longer than the distance bet ween two contours are taken,
it is not probable that the oil belt will be jumped, for the indications
near the oil are such as to be distinguished by any operator. If oil
is found, it probably lies in a narrow belt along the slope, and the
extensions of the pool should be sought along the same structure con-
tours upon which it is procured.
OIL FIELDS OF THE TEXAS-LOUISIANA GULF COASTAL PLAIN.
By C. W. Hayes.
INTRODUCTION.
Shortly after the discovery of oil at Beaumont, in 1901, the system-
atic study of the stratigraphy and structure of the Gulf Coastal Plain
was undertaken. Mr. William Kennedy spent nine months in the
field and the writer about two months collecting data for an economic
report. A report has been prepared as a Survey bulletin, and is now
in press, under the above title. The following is a brief summary of
the conclusions there stated at length :
Location of the field. — The Gulf Coastal Plain oil field includes a belt
of country from 50 to 75 miles wide bordering the Gulf of Mexico and
extending from the vicinity of the Mississippi River in Louisiana
westward about two-thirds of the distance across Texas.
TOPOGRAPHY.
While the whole of this belt is a nearly featureless plain, rising
gradually from sea level at the Gulf coast toward the north and north-
west, it may be divided into three subordinate belts, which are some-
what distinct: (1) Along the margin of the Gulf is a fringe of marsh
land only slightly above sea level and subject to occasional overflow.
This fringe is widest in Louisiana and decreases westward to the
vicinity of Galveston, beyond which it is inconspicuous or absent.
(2) Inland from the coast marsh is a somewhat broader belt of prairie
land, its surface rising inland at the rate of about a foot to the mile.
It has a stiff clay soil and is generally treeless, except for occasional
bunches of live oak and a fringe along the water courses. (3) The
third belt has a generally sandy or gravelly soil and is well wooded.
Its surface rises more rapidly and forms a less perfect plain than the
other two belts.
The only topographic features which relieve the monotony of the
Coastal Plain are occasional low mounds or swells, which rise island-
like above its even surface. These swells are of exceptional impor-
tance in the present connection, since they appear to be the external
indication of conditions which have favored the accumulation of oil
in commercial quantities. They vary considerably in size and amount
of relief. At the one extreme are the " salt islands" of Louisiana, and
345
846 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. tnuLL. 213.
High Island, Big Hill, and Damon Mound in Texas, which rise from
40 to 80 feet above the surrounding plain and contain several thou-
sand acres. At the other end of the series are the low, barely percep-
tible swells, such as Sulphur in Louisiana and Spindletop and Sour
Lake in Texas. Experience has shown that the latter afford the more
favorable conditions for oil accumulation.
STRATIGRAPHY.
The formations which underlie the Coastal Plain belong to the
latest geologic periods, the Tertiary and Quaternary, and consist
largely of unconsolidated clay, sand, and gravel. Some of the sand
beds have become cemented, forming sandstones, and there are occa-
sional beds of limestone, but these are relatively inconspicuous. The
region has been repeatedly elevated and depressed and the coast line
has migrated back and forth across it many times.
The formations of the Coastal Plain are briefly described below:
Beaumont clays. — These are brown, blue, and yellow clays contain-
ing nodules of limestone, also brown and bine sands and cypress logs;
they have a thickness of 25 to 400 feet; they generally form clay soil
and underlie the coastal marsh and prairie bell.
Columbia sands. — These are white, yellow, gray, and mottled sands
with beds of blue and yellow clay and a heavy bed of graved at base.
They occupy a broad belt inland from the Beaumont clays and pass
under the latter toward the Gulf. They have a thickness of 50 to 200
feet and form sandy and gravelly soil.
Lafayette sands. — These are blue and red thinly laminated clays
and red and brown cross-bedded sands and gravels. They have a
thickness of from 30 to 375 feet, form sandy soil, and are discrim-
inated with difficulty from the Columbia.
'Buried, beds. — These beds do not outcrop at the surface, being
entirely concealed by overlapping later formations, and are revealed
only by drilling. They consist of (a) 300 to 480 feet of blue, brown,
and gray clays and sand with thin beds of limestone and containing
small quantities of oil ; (b) 200 feet of blue clays and thin-bedded,
irregularly deposited sandstones; and (c) 300 feet of blue, red, and
gray clays and sands; thin-bedded limestones; limestones dolomitized
and associated with sulphur, gas, and petroleum, and the Spindletop
oil rock.
Frio clays. — These consist of 2G0 feet of variously colored thinly
laminated clays, containing gypsum crystals and calcareous con-
cretions.
Su mtnary. — The foregoing descriptions of the Coastal Plain forma-
tions are necessarily very much generalized since the formations
themselves vary greatly from place to place. The logs of closely
adjacent wells present only a general resemblance, and it is impos-
sible to identify with certainty any particular bed in wells separated
HAYKs.j OIL FIELDS OF TEXAS-LOUISIANA COASTAL PLAIN. 347
by a greater distance than a few hundred feet. Even in the Beaumont
district, where so much drilling lias been done, it is possible to make
only general statements regarding the stratigraphy. A part of this
uncertainty results from the difficulty of obtaining an accurate record
by means of the universally employed rotary drill, but a part also is
due to the extreme variabilitj7 in the character of the beds.
STRUCTURE.
The beds making up the Coastal Plain formations were deposited
near the margin of a sea which varied in depth from time to time, or
upon a coastal belt as wave-built beaches on river flood-plain deposits.
The surface on which they were laid down had a gentle slope toward
the southeast, and this slope was increased during their deposition
by a slight tilting. Hence the beds all have a gentle dip to the south-
east, but the lower or older beds have a somewhat greater dip than
the higher or newer ones.
While this gentle southeast dip is the prevailing structure through-
out the Coastal Plain, it is interrupted at numerous points by low
oval domes in which the beds dip away from the center in all direc-
tions. This structure has been found to characterize all hills or swells
which interrupt the even surface of the Coastal Plain. These domes
do not appear to have been formed by lateral compression, such as
has given rise to the anticlines of the Appalachian field, but rather
are due to some force acting vertically and lifting a small portion of
the earth's crust. This force appears to have become active some time
during the Tertiary and to have continued since the deposition of the
recent Beaumont clays.
CONDITIONS FOR THE ACCUMULATION OF OIL.
The conditions which are essential for the accumulation of oil and
gas in commercial quantities are everywhere the same. They are
(1) a source for the oil, either organic or inorganic; (2) a porous
stratum which may serve as a reservoir; and (3) an impervious cap
rock which will prevent its escape. Conditions which favor its accu-
mulation, but are not always essential are (4) gentle undulations of
the strata forming anticlinal arches or domes; and (5) complete satu-
ration of the rocks with water and its slow circulation.
In the Gulf Coastal Plain there appears to be a very large amount
of oil disseminated through the several thousand feet of undertying
Tertiary and Cretaceous, and possibly also Carboniferous strata.
Scarcely a well has been drilled in this region to any considerable
depth which has not encountered traces of oil in some of the beds
passed through. There is also an abundance of porous beds adapted
to form reservoirs for the oil. These are unconsolidated sands and
gravels, and in some cases, as at Spindletop, a very porous limestone
or dolomite. The impervious cover required to retain the oil and pre-
348 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213,
vent its escape from the reservoir roek to the surface is found in the
beds of clay and compact limestone which make up the "buried beds "
described in the above section on stratigraphy.
The structure of the Coastal Plain is not generally favorable for oil
accumulation. The gentle southeastward dip of the beds does not
appear to be sufficient for the easy migration of the oil to points of
accumulation, and it is only where this uniform dip is interrupted by
the dome-like structures mentioned above that accumulation has
taken place. Hence the prospector should search for these favorable
structures and while, as experience has shown, not all of them contain
oil in commercial quantities, they afford by far the most probable
localities for drilling. The elevations above the surrounding level
plain which are depended on to indicate the presence of these favor-
able structures are due to the continued action of the elevating force,
whatever it may have been, down to a very recent date. Where this
force has been most active and the elevation has been greatest, as at
High Island and Damon Mound, no oil is found. It is quite possible,
therefore, that there may be within the Coastal Plain similar struc-
tures not marked by surface elevations, even more favorable to oil
accumulation than any thus Car discovered. These can be revealed
only by the drill, but a careful study of the arrangement of the known
domes may afford valuable suggestions as to their location.
The fifth condition favorable for oil accumulation, complete satura-
tion of the strata with water, is probably very general in the Coastal
Plain, but how much circulation this ground water has and what its
effect on the accumulation of oil may be are poinls concerning which
there are few data available
THE OIL POOLS.
The actually productive oil territory, so far as at present known,
forms but an extremely small fraction of the area of the Gulf Coastal
Plain. Excepting the Spindletop pool the limits of the productive
territory are in no case defined wit li any degree of accuracy. The
separate areas or "pools," as they are generally called, will probably
be found to vary in size from 200 to 2,000 acres. In this respect the
field differs widely from the Corsicana field of central Texas and from
the great Appalachian field, where the pools are much larger, but
where the oil is in smaller quantity and generally under less pressure.
In this field productive territory has been developed at Beaumont,
Sour Lake, Saratoga, and Jennings, while encouraging indications are
found at Sabine Pass, Dayton, Columbia, Velasco, Anse la Butte,
Vinton, and a few minor localities.
Of these the Spindletop pool at Beaumont is by far the best
known. Oil was discovered in the Lucas well in January, 1901, and
within a year and a half there were 280 producing wells, and a large
number of dry wells had been drilled outside of the limits of the
hayes 1 OIL FIELDS OF TEXAS-LOUISIANA COASTAL PLAIN. 349
pool. It occupies an oval area about 3,000 feet in length and 2,700
in width, containing approximately 200 acres. The depth to the sur-
face of the oil rock varies between 000 and 1,000 feet, a few wells only
being outside of these limits. The oil rock is a crystalline dolomitic
limestone, having an extremely porous structure. The most compact
portions of the rock, as shown by the microscope, contain a larger
proportion of vacant space than most of the oil-bearing Trenton dolo-
mite of Ohio and Indiana. In addition to these minute spaces
between the crystals of the rock, such as characterize ordinary oil
sands, it contains many large cavities, certainly as much as an inch
across, and probably much more. While no accurate determination
of the relative volume of the open cavities can be made, it can hardly
be less than one-third, and may be somewhat more when account is
taken of the minute spaces between the crystalline grains. The
exceptional character of this oil rock explains in a measure the
remarkable features of the Spindletop pool. Its extreme porosity
favors the storage of a very large volume of oil, and also favors the
yielding of this oil with great rapidity when the reservoir is tapped.
It also favors the early exhaustion of the oil in the pool and its rapid
replacement by the underlying brine. It should have suggested to
those concerned in the development of the pool that a few wells prop-
erly distributed would have drained the pool quite as effectively as
the large number which have been drilled.
Associated with the dolomite, which forms the oil rock, is consider-
able selenite or crystalline gypsum. Another abundant accessory min-
eral is native sulphur. Large crystals, an inch or more in diameter,
have been obtained from many of the wells, and it is reported by sev-
eral of the drillers that the oil rock is overlain by a bed of sulphur, in
some cases reaching a thickness of 40 feet. The thickness of the oil
rock throughout the greater part of the pool is not known, though it
has been penetrated to a depth of 96 feet. Toward the western edge
it is probably less than 50 feet thick and, as shown by the Robertson
well and the Higgins No. 3, is underlain hy about 100 feet of white
gypsum. Below the gypsum the Higgins No. 3 penetrated rock salt
to a depth of 310 feet without passing through it.
Associated with the oil is always found a large amount of gas, and
at several localities this form of hydrocarbon is found unaccompanied
with oil. The composition of the gas has not been carefully investi-
gated, but it is known to contain in addition to the light hydrocar-
bons a large proportion of sulphureted hydrogen.
At nearly all points in this field where oil has been found in com-
mercial quantities it occurs under great pressure, which gives rise to
the familiar phenomenon of gushing. Just how high the pressure
has been in the Spindletop pool is not known, but it appears to vary
between wide limits. In some wells it has shown almost explosive
violence, blowing out casing and breaking heavy cast-iron valves.
350 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [hum,. 213.
This maximum pressure has never been even approximately measured.
Some elosed pressures of 500 pounds and over per square inch have
been reported, but these are not well vouched for, and the only reli-
able measurements vary from 79 to 350 pounds.
While the cause of this pressure is not certainly known, it appears
highly probable that it is due largely, if not entirely, to the expansive
force of the associated gas. When the oil rock is penetrated by the
drill it is usually necessary to remove the water from the casing by
bailing. When the pressure is thus relieved there is first a rush of
gas, followed by a stream of oil, which is expelled with great violence.
The oil, however, never flows in a steady stream, like water from an
artesian well, but by a series of jets or pulsations. These may be
relatively slow, each flow lasting for several minutes, followed by an
equal or longer period of quiescence in which only gas escapes; or
they may be rapid, several pulsations occurring in a single minute.
The rapidity of the pulsations appears to depend, among other things,
upon the depth to which the well is drilled into the oil rock. Their
rapidity and consequently the yield of the well is generally increased
by deeper boring.
In addition to the expansive force of the gas there is also probably
some hydrostatic pressure in this field, but its influence in producing
the phenomena of a gusher must be relatively insignificant. The
existence of a slight hydrostatic pressure in the Spindletop pool is
shown in the invasion of some wells by salt water, which was first
noticed after the pool had been producing about eighteen months.
This invasion will continue as the oil is removed, though the head may
not be sufficient to bring the salt water to the surface.
If the pressure producing the gushing in an oil pool is due chiefly
to the expansive force of gas, it follows that this force will expel only
a part of the oil, and the remainder will necessarily be won by pump-
ing or by supplying the place of the natural gas by compressed air.
It is evident, therefore, that the gas should never be allowed to escape
freely from an oil pool, for, aside from the waste of a valuable fuel,
the force needed to expel the oil is at the same time being lost.
The history of the Spindletop pool is very instruct ive in this con-
nection. The Lucas gusher came in in January, 1901, and was wild
for nine days, during which the flow is variously estimated from half
a million to a million barrels. Drilling at once became very active,
and within a year about 200 wells had been completed within the
productive territory, which was then well defined. The pressure
undoubtedly began to decline within three months or less after the
field was opened, though it was still so high that the decline was not
readily noticeable. At the end of the first year of production the
pressure, although still manifesting itself occasional^ with almost
explosive violence, was perceptibly lowered. New wells rarely gushed
spontaneously, as at first, but required bailing to remove the entire
hayes.1 OIL FIELDS OF TEXAS-LOUISIANA COASTAL PLAIN. 351
column of water and oil in the casing. Wells which had been shut
off did not generally flow when the valves Avere opened, but to induce
a flow it was necessary to agitate the oil in the casing, either with a
bailer or by conducting compressed air to the bottom of the well.
This general decrease in pressure continued until in the latter half of
the second year few wells had a natural flow, and in some the oil was
cut off by the invasion of salt water. This fate awaits every well in
the pool, and it is only a matter of time when even pumping will no
longer be profitable.
The development of this pool has been accompanied by enormous
waste in the drilling of a large number of unnecessary wells and the
loss of great quantities of oil, which has been allowed to flow over
the surrounding country and invite further loss by fire. The even
greater loss which has been inflicted upon the commercial world by
the overcapitalization of oil companies and the sale of worthless stock
is a matter which might be dwelt upon at length, but is not germane
to the present discussion.
CHARACTER AND UTILIZATION OF THE GULF COAST
PETROLEUM.
The character of the oil found in various parts of the Texas-Louisi-
ana Gulf Coastal Plain is practically the same, but it is very different
from that found in other fields of the United States. It is dark
reddish-brown, almost black, and has a disagreeably pungent sul-
phurous odor. It has a high specific gravity, varying from 0.904 to
0.963, Pennsylvania petroleum having a specific gravity from 0.800 to
0.817. In this, as in other respects, it is more nearly related to the
California oils.
The flash point or the lowest temperature at which the oil gives off
an inflammable vapor varies, according to different observers, from
110° to 180°. The wide variation is probably due to the different
lengths of time the several samples on which the tests were made had
been -exposed to the air Since the flash point depends on the pro-
portion of the lighter hydrocarbons in the oil, it is gradually raised
by exposure to the air, which permits these lighter constituents to
escape.
The oil contains a large amount of sulphur, both as hydrogen
sulphide, which largely escapes on standing and is more thoroughly
expelled b}T blowing air or steam through the oil, and also as other
sulphur compounds. After freeing it from the hydrogen sulphide it
has been found by various chemists to contain from -1.75 to 2.4 per
cent of sulphur. At least a part of this appears to be sulphur as
such simply dissolved in the oil and not in chemical combination. It
is probable that this high sulphur would not form a serious obstacle
to the utilization of the oil for the preparation of illuminants. The
chemical constitution of the distillates, however, apjDears to be such
352 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
that with any refining process now in use the yield of illuminants is
small and the quality poor.
It is as a fuel that the Coastal Plain oil has thus far been chiefly
utilized, and this will probably continue to be its principal use in the
future. Tested in various forms of calorimeter, this oil is shown to
have practically the same heating value as Pennsylvania petroleum,
which is regarded as the standard liquid fuel. Practical tests in
steam raising have been made with the Texas oil, and it has been
found to have an evaporative power of 15.29 to 15.55 pounds of water
per pound of oil used. Of the steam generated 3.1 to 4.8 percent
was used by the burner in sprajing the oil. There was thus left
available for use the steam from 14.74 to 15.16 pounds of water per
pound of oil used. In ordinary practice, without the use of special
precautions to guard against waste, 13 pounds of water should be
evaporated by 1 pound of Texas oil, as compared with 6 to 6.5 pounds
by the bituminous coals of Indian Territory, 8.7 pounds by Pittsburg
coal, and 9 by Pennsylvania anthracite. From these relative fuel
values it appears that 3.1 barrels of Texas oil may be regarded as
having the same fuel value as 1 ton (2,000 pounds) of Southwestern
bituminous coal and 4.31 barrels of oil as 1 ton of Pittsburg coal.
It should be noted, however, that the conditions under which coal
and petroleum are used in ordinary practice favor the obtaining of a
larger per cent of the theoretical fuel value in the petroleum than in
the coal. Also a deduction of at least 10 per cent should ordinarily
be made from the fuel cost of petroleum on account of the economy
in handling the liquid fuel as compared with coal.
As a locomotive fuel petroleum has many additional advantages
over coal. Practical tests have shown that its use may add as much
as 30 per cent to the efficiency of the boiler, while it weighs only 07
per cent as much as coal having the same heating capacity. From
these tests it appears that with coal at $3 per ton petroleum should
be worth 97 cents per barrel as a locomotive fuel.
ASPHALT DEPOSITS OF PIKE COUNTY, ARK
By C. W. Hayes.
The Trinity group, which is the lowest member of the Cretaceous
in Arkansas, Indian Territory, and Texas, consists largely of coarse
unconsolidated sands with some beds of clay, and is overlain by
highly fossiliferous limestones. In Arkansas the Trinity beds rest in
an almost horizontal position upon sandstones and shales of Paleozoic
age. These older rocks have been intense \y folded, the dips being
from 50° to 90°. After the folding, but prior to the deposition of the
Trinity sands, much erosion took place, so that the Trinity beds were
I deposited on an uneven surface composed of these folded Paleozoic
rocks. Both Trinity and Paleozoic were, at a still later date, covered
by a thin and irregular deposit of coarse sand and gravel called the
Lafayette.
At many points in the area under discussion the sands of the
Trinity group contain notable quantities of bituminous matter,
usually in the form of asphalt, though in Texas small quantities of
petroleum are reported to occur at this horizon.
The most extensive of these deposits occurs in Pike County, about
2^ miles southeast of Pike City, on a branch of Wolf Creek. This
has recently been developed by the Arkansas Asphalt Company, of
Little Rock. Two hills south of Wolf Creek contain in their upper
portions the fossiliferous limestones of the Lower Cretaceous, and
around their bases and extending under them is the Trinity sand.
The asphaltum deposit occurs in a depression between these hills,
where only the lower portion of the Trinity formation remains, con-
sisting chiefly of coarse sand, in some places quite calcareous, with
beds of clay. The deposit is in the form of a sand stratum, which
varies in thickness from 0 to 12 feet, more or less thoroughly
saturated with asphaltum. The deposit was discovered by the escape
of small quantities of asphaltum to the surface in a spring, and this
led to prospecting for its source. A pit was dug about 12 feet in
depth, passing through the bed, and the thick, viscous asphalt has
slowly oozed out into this pit for the last thirty years.
The asphaltic rocks show considerable variation in character and
in the amount of asphaltum which they contain. This variation is
shown by the following analyses made for the Arkansas Asphalt Com-
pany by G. W. Howard, of New York City.
Bull. 213—03 23 353
354 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull.*
Specimen No. 1, known at the pit as brown cap sand, contains 5.0C
per cent of bitumen, or 1.73 per cent of petrolene and 3.33 per cent of
asphaltene. It is essentially a sandstone, since it contains 92.40 pei
cent silica.
Specimen No. 2 is a black sand rock containing 16.53 per cent bitu-
men, of which 14.13 per cent is petrolene and 2.40 per cent asphaltene.
The percentage of silica in this rock is 81.20.
Specimen No. 3, a grayish rock exhibiting banding, contains 0.(38
per cent of bitumen, 69.15 per cent of silica, and 20.35 per cent of
carbonate of lime.
Specimen No. 4 is a black, gummy rock carrying 8.86 per cent of
bitumen, 7!). 50 per cent of silica, and 0.14 per cent of carbonate of
lime. The bitumen determined as petrolene amounts to 6.61 per cent,
and the asphaltene to 2.25 per cent.
Specimen No. 5, which is a calcareous sandstone, contains 4.58 per
cent bitumen, which equals 3.46 per cent petrolene and 1.12 per cent
asphaltene. The carbonate of lime in this specimen amounts to 46
per cent, and the silica to 49.42 per cent. At the pit this rock is known
as limestone.
No doubt specimens taken from these classes of rock would vary
from place to place in the pit. The analyses, however, probably rep-
resent fairly the materials obtainable.
Like similar deposits in other regions, there can be little doubt that
this asphalt um is merely the residuum from petroleum, the lighter
and more volatile portions of which have escaped by evaporation. It
lias also doubtless Undergone certain chemical changes, chiefly oxida-
tion, during its long exposure to atmospheric conditions.
By means of test borings the asphaltuni bed lias been proved to
extend over a number of acres, under a cover sufficiently thin to per-
mit profitable mining by stripping. At the time the deposit- was last
visited, in November, L902, a pit about 100 feet in diameter had been
opened and a tramway built to the railroad, about- half a mile distant.
It is proposed to use the materials in such proportions as will pro-
duce a good paving mixture. The occurrence of the limestone with
the sandstone makes this possible without the addition of material
from other sources. A practical test will be made at Little Rock,
where a contract has been obtained for paving certain streets.
The utilization of this deposit is a technical matter which can not
be entered upon here. Its chief value will doubtless be as a paving
material. As stated above, some portions of the bed form a natural
paving mixture, which hardens on exposure to the sun, and, so far as
could be judged, would be fully as durable as the ordinary artificial
mixtures made from Trinidad asphalt. Other portions are too rich
to be used in a natural state. Tests of these portions in the prepara-
tion of a paving mixture have been made by the St. Louis Testing and
Sampling Works, with excellent results.
hayes.] ASPHALT DEPOSITS OF PIKE COUNTY, ARK. 355
The extent to which the deposit can be used for paving purposes in
competition with other asphalts will be determined entirely by the
matter of freight rates. It should easily control the market in near-by
cities, such as Little Rock, Texarkana, and Fort Smith, and the
richer portions of the deposit should compete advantageously with
other asphalts in cities as distant as Memphis and St. Louis.
No experiments have yet been made in refining the asphaltic sand
for the preparation of pure asphaltum, and this may be found to be
more profitable than shipping the crude product.
From the large amount of bituminous matter in these sands, it was
inferred that petroleum in commercial quantities might be found by
deep boring, and two wells were drilled for oil. The wells penetrated
from 100 to 120 feet of the Trinity formation, consisting chiefly of
sands and clays, with a few thin seams of limestone, and then entered
the Paleozoic sandstones and shales. The latter are highly contorted,
dipping at angles of 45° to 55°, and are intersected by numerous
fractures. No oil in commercial quantities has ever been discovered
in rocks of this character, and it will readity be understood that, even
if they had originally contained oil, it would, before the deposition of
the Trinity, have had abundant opportunity to escape to the surface
through the fractures which resulted from the folding of the strata.
The expectation of finding oil, therefore, in this region at greater
depth than 100 or 200 feet, that is to say, in the underlying Paleozoic
rocks, has no rational basis. Also, it need not be expected that oil
in commercial quantities will be found at shallower depths, since the
conditions are not favorable for its retention in these sands.
In view of the foregoing considerations, deep drilling in this region
is not justified by even a remote probability of finding oil in commer-
cial quantities. On the other hand, the conditions for the accumu-
lation of asphaltum are most favorable, and it \p quite probable that
other valuable deposits will be found in this region, similar to that
above described and at the same horizon.
PUBLICATIONS ON OIL, GAS, AND ASPHALT.
The following list contains the more important papers relative to
oil, gas, and asphalt published by the United States Geological Sur-
vey or by members of its staff :
Adams, G. T. Oil and gas fields of the western interior and northern Texas
coal measures, and of the Upper Cretaceous and Tertiary of the western Gulf coast.
Bulletin U. S. Geol. Survey No. 184, 64 pp. 1901.
Eldridge, G. H. The Florence oilfield, Colorado. In Trans. Amer. Inst. Min.
Eng., Vol. XX, pp. 442-462. 1892.
— The uintaite (gilsonite) deposits of Utah. In Seventeenth Ann. Rept.
U. S. Geol. Survey, Pt. I, pp. 909-949. 1896.
— The asphalt and bituminous rock deposits of the United States. In
Twenty-second Ann. Rept. U. S. Geol. Survey, Pt. I, pp. 209-452. 1901.
Fuller, M. L. The Gaines oil field of northern Pennsylvania. In Twenty-
second Ann. Rept. U. S. Geol. Survey, Pt. Ill, pp. 573-628. 1902.
Griswold, W. T. The Berea grit oil sand in the Cadiz quadrangle, Ohio.
Bulletin U. S. Geol. Survey No. 198, 43 pp. 1902.
Hilgard, E. W. The asphaltum deposits of California. In Mineral Resources
U. S. for 1883-1884, pp. 938-948. 1885.
McGee, W J. Origin, constitution, and distribution of rock gas and related
bitumens. In Eleventh Ann. Rept. U. S. Geol. Survey, Pt. I, pp. 589-616. 1891.
Phinney, A. J. The natural gas field of Indiana. In Eleventh Ann. Rept.
U. S. Geol. Survey, Pt. I, pp. 617-742. 1891.
Richardson, C. Asphaltum. In Mineral Resources U. S. for 1893, pp. 626-669.
1894.
Vaughan, T. W. The asphalt deposits of western Texas. In Eighteenth Ann.
Rept. U. S. Geol. Survey, Pt. V, pp. 930-935. 1897.
Willis, B. Oil of the northern Rocky Mountains. In Eng. Min. Jour., Vol.
LXXII, pp. 782-784. 1901.
356
STONE.
Several brief papers on building stone are here presented. During
the last year other extensive investigations in various important
quarry districts have been commenced by the Survey, the results of
which are not yet in form for publication here. The slate industry
has been given particular attention, reports being published or in
preparation on the slates of Vermont, New York, Pennsylvania,
West Virginia, and Georgia.
THE STONE INDUSTRY IN THE VICINITY OF CHICAGO, ILL."
Bv William C. Alden.
LIMESTONE.
The supply of limestone within the Chicago district, so exposed or
so thinly covered as to be easity reached, seems to be quite adequate
to the demand; at least, not all the exposures are utilized for the pro-
duction of the commodity. The exposures are so distributed as to be
convenient to Chicago and its nearest suburbs, but the country dis-
tricts lying in the morainal track are not so well supplied.
BUILDING STONE.
The strata considered by Dr. Bannister as the lower division of the
Niagara group afford one of the best building stones in the State.
These are exposed on the floor of Desplaines Valley northeast of
Lemont. The location, being formerly known as Athens, gave the
name "Athens marble" to the rock, by which name it is known wher-
ever used. The same beds are seen in the western end of the Sag, at
its junction with Desplaines Valley. The rock at the Western Stone
Companj^'s quarries, Lemont, is a fine-grained, even-textured lime-
stone, of an agreeable light-drab color when first taken from the
quarry. On exposure to the air the color changes to a buff or yellow.
The rock rubs well, though not capable of receiving a very fine polish.
a Abstract from Geologic Atlas U. S., folio 81, Chicago.
357
358 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.1
It is regularly bedded, the layers ranging from 6 inches to nearly 3
feet in thickness, thus affording fine cut and sawed dimension stone
and flagging.
The quarries of the Illinois Stone Company in the same vicinity
show the same even-bedded limestone and produce dimension and
rubble stone and flagging.
At Sag Bridge the quarries of the Phoenix Stone Company produce
a fine grade of even-grained, solid limestone. The courses increase
in thickness downward, becoming nearly 8 feet thick at the bottom,
with little or no fracturing. The product is fine cut and sawed
dimension stone, rubble, and five grades of crushed stone for
macadam.
The quarry of the Calumet Stone Company, 1-J miles east of Sag
Bridge, shows stone of excellent quality. A small quarry on t he north
side of the Sag has turned out a small amount of a dense, fine-grained
rock of very good quality.
These are the principal localities yielding good dimension stone, as
here the strata have suffered little or no disturbance and hence show
little fracturing. The facilities for transportation by railroad and by
canal are excellent.
The quarry 1 mile west of Elmhurst, on the Chicago and North-
western Railway, puts out building stone, including some dimension
stone.
RUBBLE, MACADAM, AND LIME.
As most of the quarries furnish crushed stone for macadam and
rubble for foundations, and sonic furnish lime, they will be noted in
oidcr, beginning with those in Chicago. The rock at all the quarries
is well adapted for macadam, as it is a hard, gray dolomite, in places
very siliceous, and the fractured condition of the strata makes it com-
paratively easy to remove. At the intersection of Chicago and West-
ern avenues, about three-fourths of a mile southeast of Humboldt
Park, the quarries of the Artesian Stone and Lime Works Company
produce crushed stone for macadam and lime.
The quarries of the Chicago Union Lime Works Company at the
intersection of Nineteenth and Lincoln streets, about a mile east of
Douglas Park, have been excavated to a depth of 175 feet. The lime-
stone is a dolomite containing about 54 per cent carbonate of lime and
44 per cent carbonate of magnesium.
The quarries of the Stearns Lime and Stone Company at Bridge-
port, near Twenty-seventh and Halsted streets, produce lime and
crushed stone for macadam.
The quarries of Dolese & Shepard, at Hawthorne, on the Chicago,
Burlington and Quincy Railway, produce building and dimension
stone, crushed stone for macadam and concrete, and limestone for
flux.
At Thornton, on the Chicago and Western Indiana Railroad, the
iLDEN.] STONE INDUSTRY IK VICINITY OF CHICAGO, ILL. 359
faarries of the Brownell Improvement Company produce crushed stone
or macadam containing about 36 per cent of silica, giving it a very
iurable quality. Their quarries at Gary, 111., on Desplaines River,
produce a dense, even-grained limestone in little-fractured strata.
"I Some foundation stone is gotten out, but the rock is rather hard to
dress. The product is largely crushed stone for paving.
At the outcrop, 1 mile southwest of Blue Island, considerable rock
has been removed for foundation stone. It is stated that a bed of
bluish, impure limestone has been worked here for hydraulic cement.
Mi'. .1. V. <t>. Blaney reports the following analysis of this limestone:
Analysis of limestone 1 mile southeast of Blue Island.
Clay and insoluble matter 4:5. 56
Carbonate of lime 31. 60
Carbonate of magnesium 22. 24
Peroxide of iron 1 . 20
Soluble silica ' .16
Alkalies, loss, etc . 1. 30
Total 100. 06
At his place about 2 miles southwest of Blue Island, Mr. Henry
Schwartz has quarried a limited amount of good foundation stone.
There is abundant rock here, easily accessible.
The quarry 1 mile west of Elmhurst, on the Chicago and North-
western Railway, produces crushed stone.
The quarry of Kogle & Smith, about 3 miles southeast of Elmhurst,
yields crushed stone. Some building stone is also taken out.
At the outcrop, 1 mile northwest of Lagrange, on the bank of Salt
Creek, a quarry has been opened which is turning out crushed stone
for macadam.
Mr. Fred Schultz puts out crushed stone and lime from his quarry
at Lyons.
At McCook, on the Santa Fe Railway, near the canals, are the quar-
ries of the Chicago Crushed Stone Company. Rubble for foundations
is also produced.
Not all of the rock exposures have been utilized for economic pur-
poses. The following may be noted as affording productive sites
should the demand require: One mile northwest of Humboldt Park;
corner of North Central Park avenue and Humboldt avenue; two
blocks west of Humboldt Park; in the vicinity of Robey and Twenty-
third streets; on the lake shore in Windsor Park, at the foot of Chel-
tenham place; on either side of Railroad avenue, between Ninety-
fourth and Ninety-fifth streets, and six blocks west, between Ninety-
fifth and Ninety- sixth streets.
At " Stony Island " two quarries have produced considerable rock,
but are now unused. There is abundant rock thinly covered north
and west of Thornton. Two miles south of Grlenwood and three-
360 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
fourths of a mile east of the Chicago and Western Indiana Railroad
the rock is rather thinly covered in the hill slope. Three and one-half
miles south of Elmhurst rock can be obtained in the west bank of Salt
Creek. Abundant rock is thinly covered south and east of Lyons;
also down Desplaines Valley from McCook, along the north side of
the river. At Sag Bridge and at Leinont abundant rock is easily
quarried. The southwestern part of the area is most poorly supplied,
though the proximity of Joliet may counterbalance this deficiency.
Only two exposures were noted in this part of the area, one 5 miles
east of Orland, along the banks of a small creek; the other along the
bed of Hickory Creek, near New Lenox.
Where the bituminous limestone has been used for building pur-
poses the staining gives a peculiarly venerable appearance to the
structure. There is, however, the disadvantage that the melting and
running out of the bitumen may give a disagreeable streaking to the
walls.
The abundant drift bowlders of limestone, sandstone, igneous and
metamorphic rocks have furnished material for many picturesque
and beautiful buildings within the district and could supply a further
demand. These are also of value in the construction of piers and
breakwaters.
SAND AND GRAVEL.
The wide distribution of sand and gravel over the Chicago Plain
has afforded abundant material for building sand, roofing and road
gravels, and for filling. The extensive deposits of dune sand along
the present lake shore, along the west side of the Blue Island ridge,
southwest and south of Hammond, Ind., and east of Thornton, furnish
abundant fine, clean sand. The deposits of glacial gravel furnish
the coarser gravels, with some sand and fine gravel. Several large
pits have been opened about a mile north of Willow Springs, in the
north slope of Desplaines Valley. The deposits here are assorted into
several grades of gravel for building, paving, and ballast purposes.
The output at these pits is 20 to 25 carloads per day. Numerous pits
have been opened at various points along Desplaines Valley, showing
material grading from sand and gravel to very stony till, composed
almost entirely of well-*worn limestone pebbles and bowlders. In
places this limestone is partially cemented into a conglomerate, so as
to come out in large masses. One-half mile southwest of Worth
Messrs. Henke & Read have opened a large gravel pit. The gravels
here are assorted into grades of two sizes. Ten to twelve thousand
cubic yards have been taken out per annum. At Blue Island, just
north of the Chicago, Rock Island and Pacific Railway station, there
is an extensive deposit of the coarser beach gravel. The entire south
end of the ridge seems to be composed of these gravels.
THE SLATE INDUSTRY AT SLATINGTON, PA., AND MARTINS-
BURG, W. VA."
By T. Nelson Dale.
SLATINGTON, PA.
The basis of the slate industry here is a belt of Lower Silurian
(Hudson) slates, shales, and grits which stretches along the southern
side of the Blue or Kittatinny Mountain from east-northeast to west-
southwest. This formation is about half a mile thick, overlying the
great magnesian limestone formation on the south and underlying the
Upper Silurian conglomerate and sandstone on the north. The struc-
ture of this formation is a succession of minor folds generalty over-
turned to the north, and in places crossed by a southward-dipping
slaty cleavage.
Although the formation covers many square miles of Lehigh County,
west of the Lehigh River, and prospects have been made at man}^
points, yet the Slatington industry is confined to an area of 3 to 4
square miles along Trout Creek and its branches. Within that area
about 100 openings have been made, of which only about 45 are now
being worked. These range from 50 to 300 feet in depth.
The slate is black and has a very fine cleavage. It is calcareous, as
shown by its effervescing in cold dilute hydrochloric acid, and contains
carbonate of iron, as shown by its discoloration after continued expo-
sure. Under the microscope it is found to consist of a matrix of mus-
covite (potash mica), with much carbonate, carbonaceous matter, and
pyrite, some angular quartz and feldspar grains, chlorite scales, and
the usual slate needles (rutile, Ti02). It is geologically between a
phyllite and a clay slate. The roofing-slate industry here seems to
owe its success largely to the fine cleavage, which enables the pro-
ducers to undersell slates of more durable character, but of poorer
fissility. Some beds unsuitable for roofing are made into school
slates. A large establishment for the manufacture of school slates
has just been erected.
The slate beds vary in thickness and alternate with grit beds from
a fraction of an inch to several feet in thickness. The gril consists
mainly of quartz grains, carbonate, carbonaceous matter, and pyrite.
It represents coarser marine sediments, brought in possibly by shift-
'i Detailed reports on these areas are in preparation.
361
3(32 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
ing currents, while the slate is the finer off-shore material powerfully
compressed and largely altered to mica.
The chief difficulty attending the Slatington slate industry is the
complex structure of the slate beds. The frequency of the grit beds,
"rock" or " ribbon " of the quarrymen, is one element in this. Then
the folds vary greatly in width. One limb of a trough (syncline) may
measure over 200 feet at the horizon or the arch (anticline) maybe so
sharp as to measure scarcely 25 feet across. These folds are more or
less overturned, so that the ribbon intersects the cleavage at different
angles on the sides of the fold, thus differently determining the size
of the slate blocks and to some extent the quality of the slate. The
axes of these overturned folds pitch alternately east -southeast and
west-northwest at from 5° to 10° or bend 10° laterally, i. e., north-
south. The folds have all been truncated at the surface by erosion,
so that it is difficult to trace any one bed across the strike. The
rock surface may be but a few inches below the turf or may be
buried beneath 30 to 40 feet of glacial deposits. There is frequently
a flexure of the cleavage ("curl") for a few inches near the ribbon;
more rarely there is a curvature of the cleavage across the entire bed.
Slates cut from such beds are called "bents," and are used for cov-
ering curved or conical roofs. At the old Hughes quarry this curva-
ture in 25 feet along the dip of the cleavage amounts to a change of
20° in the dip, the dip at the top being 45°, but 05° below. Exception-
ally the joints, instead of crossing bedding and cleavage at a certain
angle, undulate like bedding planes. Faulting seems to occur rarely.
It would seem that nothing less than an exhaustive study of the
stratigraphy of the region with the aid of a perfectly reliable large-
scale topographic map would suffice to furnish a safe basis for
such an industry, but in fact the industry has attained its present
prosperity without such aid, and it is even doubtful whether a
pocket compass could be found on the person of any foreman in the
quarries. In view of the very small collective area of all the open-
ings about Slatington compared to the extent of the slate beds as
shown by the location of these openings, and in view also of the finan-
cial risks growing out of the difficult st rat tgraphy, it is surprising that
the diamond drill, used so effectively in marble and other regions, has
not been brought into requisition here also. The core from such a
drill would not only show the quality of the slate but its thickness,
in many cases, as well as the dip of the cleavage and ribbon. A
less costly drill, which secures a core by the rotation of a wrought-iron
pipe upon steel shot, has been successfully used in the Vermont slate
belt.
Attention ought to be called to certain outcrops of dark reddish
shales a mile southeast and southwest of Werleys Corners in Weisen-
berg, or about 1-0 miles southwest of Slatington. A microscopic exam-
ination of a surface specimen from the first of these places shows it to
e*ale.] SLATE INDUSTRY OF PENNSYLVANIA-WEST VIRGINIA. 363
be almost a slate. It is possible that a dark red clay slate, suitable
,for roofing, oecurs below the top roek in that vicinity.
MARTINSBURG, W. VA.
This recently prospected slate district lies in Berkeley County, W.
Va., within the geologic belt designated Martinsburg shale in the
Harpers Ferry folio. This belt lies about 13 miles west of the Blue
Ridge and mostly on the western side of Opequon Creek, a tributary
of the Potomac. It measures at least 14 miles in length, from north-
northeast to south-southwest, and from 2 to -1 in width. Martinsburg
lies just beyond its western edge.
This shale and slate formation, estimated to be from 700 to 1,000 feet
in thickness, is of Lower Silurian age, and overlies the Siluro-Cambrian
Shenandoah limestone in a series of folds represented in the folio
as overturned to the west. The rock is generalty a dark grayish
shale, weathering into a yellowish or white clay, known locally as
"soapstone." The general character of this rock and its appearance
when weathered would hardly be regarded as good indications of the
presence of roofing slate. But at several points, usually near the
Opequon or its tributary "runs" or creeks, where the mass has been
denuded of its weathered portions, it has a well-marked easterly dip-
ping' (in one case, westerly) slaty cleavage crossing the bedding at
various angles; and pieces, when struck with the hammer, give the
typical ring of a slate. A superficial examination of this slate shows
that its cleavage is far from being as fine as that of the Slatington
quarries and that the cleavage surface, although quite as black, yet
lacks the smoothness and luster of the Slatington product, On the
other hand, it effervesces far less readily or not at all with cold dilute
hydrochloric acid. Its relative commercial value will be soon deter-
mined scientifically by the usual physical and chemical tests and by
comparing the results of these tests with those obtained from tests of
"Peach Bottom" slates. Meanwhile preliminary microscopic exam-
inations of specimens taken from several localities have been made
with the following results.
All the transverse sections show a rather coarse and poorly defined
cleavage and a very faint polarization of the matrix, in some cases
none at all, indicating incomplete sericitization. All the sections
show carbonate, some in very small amount, others in large. Car-
bonaceous matter is present in all the sections, but is less conspicu-
ous than in the Slatington slates. The following minerals are also
present: pyrite in spherules, angular quartz grains, plagioclase grains
very rarely, rather large muscovite scales, chlorite usually interleaved
with muscovite, and the usual slate needles (Ti02), but these are not
as abundant as in other slates.
The above suffices to show that these slates are neither true phyl-
lites nor midway between phyllites and clay slates, like the Slatington
364 CONTEIBUTIONS TO ECONOMIC GEOLOGY, 1902. [nmx.2ia
and Vermont slates, but are closely related to clay slates. They
resemble in structure, but not in composition or color, the Welsh
Penrhyn dark purple ("red") slates/'
Microscopic examination shows that the slates will cleave less read-
ily than the Slatington or Vermont " sea-green " slates, and that they
will be liable to lose some of their blackness on continued exposure,
and that the amount of discoloration will vary in different beds and
localities. Although a clay slate even with a small amount of car-
bonate could hardly prove as durable as a phyllite without any, yet
it may compare favorably with slates intermediate between phyllites
and clay slates and containing much more carbonate.
Slate has been found at the following points in the Martinsburg
belt: Two miles north 10° west of Middleway, or about 9 miles south of
Martinsburg, 5 miles northeast, 3£ miles northeast, 2'^ miles southeast,
2^ and 5| miles south-southeast, 6| miles south-southwest of Martins-
burg. Numerous other localities will probably be found. The cause
for the development of slaty cleavage at one point in the shale belt
and not at another is not yet clear. Thus the railroad and highway
cuts east of Martinsburg along Tnscarora Creek, which bisects the belt,
are in shale, but slate occurs north-northeast and south-southwest of
this along the strike.
What is needed to develop the industry is to thorough^ open one
experimental quarry and introduce its product into the market.
Should that experiment prove successful the growth of the industry
will be assured.
aSee Nineteenth Ann. Rept. lT. S. Geol. Survey, Pt. Ill, p. 2H2.
LIMESTONE OF THE REDDING DISTRICT, CALIFORNIA.
By J. S. Diller.
More limestone occurs in the copper region of Shasta County, Cal.,
than in an equal area of any other part of the State. A thick lime-
stone of Triassic age occurs along the stage road east of Furnaceville,
and subordinate masses crop out around the upper slope of Bear
Mountain a few miles northwest of Sherman, but the principal mass
of this belt forms Brock Mountain, on Squaw Creek, and may be
traced for many miles to the north. This limestone is full of fossils
and is especially noted for the large lizard-like animals it contains.
It is generally pure, and at Brock Mountain is used for flux in the
Bully Hill smelter.
A belt of more prominent limestone ridges and peaks extends from
near Lilienthals north b}r Grey Rock, the Fishery, and Hirz Moun-
tain, along the McCloud for many miles. The limestone where best
developed is over 1,000 feet thick, and until recently has been used
for flux at Bully Hill. It is cut by numerous irregular dikes of igne-
ous rock, which locally interfere with quarrying. If the projected
branch railroad up Pit River is ever built, it would pass near this
great limestone.
A third belt of limestone occurs near Kennett, within a few miles of
the railroad, and furnishes not only flux for the Mountain Copper
Company at the Keswick smelter, but also lime, which is burned at
Kennett and shipped to many points on the Southern Pacific Rail-
road. This limestone is of Devonian age, and consequently much
older than the others. Although the limestone is not nearly as large
as the others, and isolated on ridge crests by igneous rocks, it is more
valuable because more accessible. Smaller masses occur near Horse-
town and at several points on the plain no: oheast of Buckeye where
lime has been burned, but since the Kennett locality has been opened
they are of little importance.
365
TENNESSEE MARBLES."
By Arthur Keith.
STRATIGRAPHY.
Beds of workable marble are found in a belt in the center of the
valley of East Tennessee, extending nearly across the State. The
general belt is composed of a number of nearly parallel bands or lines j
of outcrop of the marble formation. They were brought into their
present attitudes during the folding of the strata of that region, and
bear their present relations to the surface in accordance with the
progress of erosion of the rock materials. The exposures of the mar-
ble are to be seen in the following counties, beginning at the north-
east: Hawkins, Hancock, Hamblen, Grainger, Claiborne, Union, Knox,
Sevier, Blount, Roane, Loudon, Monroe, and McMinn.
All of the marble is found in the strata of Silurian age, much the
greater part of it in the Chickamauga limestone. On account of the
prominence and extent of the marble in that formation near Ilolston
River, it has been called "Ilolston" marble in the folios of the United
States Geological Survey. A considerable development of marble is
also seen in the lower portion of the Sevier shale in Sevier, Knox,
Blount, and Monroe counties. Practically all the quarrying has been
done in the Chickamauga limestone, although in Knox and Blount
counties some of the higher beds have also been used to a small extent.
In the lower part of the Chickamauga formation are many beds of
more or less coarsely crystalline marble. These do not appear,
except in a most local way, northwest of the S3mclinal fold from
which Clinch Mountain rises. In that syncline and southward, how-
ever, marble is usually well developed in all the areas of the forma-
mation. It is from 600 to 650 feet thick near Clinch Mountain and
thins in all directions from that area. Its average thickness is 300
to 400 feet, where well developed. The position of the marble beds
in the limestone varies much from place to place. Usually there is a
considerable thickness of blue and gray limestone below the marble;
north of Clinch Mountain, however, this is not the case, as the marble
beds are thicker and rest directly upon the Knox dolomite. The
same condition was observed on the south side of Black Oak Ridge.
a A resume of material presented in folios of the Geologic Atlas of the United States.
366
Keith] TENNESSEE MARBLES. 367
The marble differs from most of the rocks of the formation in
being coarsely crystalline. It may have been altered after its forma-
tion by the passage of water through the rock, dissolving and recrys-
tallizing the carbonate of lime, or it may have been deposited in its
present form. The shaly parts containing less lime are not crystal-
line. The forms of the fossils inclosed in marble are plainly visible,
although wholly recrystallized. The marble varies considerably in
color, most of the rock, however, being of two types, a dark bluish
gra}^ and a variegated reddish brown or chocolate. Of these two
varieties the latter or reddish marble is considerably more common.
Both are extensively quarried for ornamental stone.
Workable beds are rarely over 50 feet thick, and usually in that
thickness there is a combination of several varieties. Quarries far
separated from one another have quite distinct series of beds, and
each quarry has its special variety of marble. All marbles of this
region are free from any siliceous impurity, and all of reasonable
purity take a good polish and are unaffected by weather.
The total thickness of the marble beds is by no means available for
commercial use. The rock must be of desirable color, must quarry in
blocks of large size free from cracks or impure layers, and must be of
fine, close texture.
The variations in all of these characters are duo to differences in
the sediment at the time of its deposition. Carbonate of lime, iron
oxide, and clay were deposited together with shells of large and small
mollusks. The firmness of the rock depends upon a large proportion
of the lime, while the dark, rich colors are due to the oxide of iron;
but if the latter be present with clay in large proportion the rock
becomes a worthless shale. The colors vary from cream, yellow,
brown, chocolate, red, and pink to blue, in endless variety. Absence
of iron oxide results in gray, grayish white, and white. The colors
are either scattered uniformly through the rock or are collected into
separate crystals or patches of crystals; forms such as fossils are
usually of pure, white calcite. The curious and fantastic arrange-
ment of the colors is one of the chief beauties of these marbles. Like
the shaly matter, the iron oxide is an impurity, and the two are apt
to accompany each other. The most prized rock, therefore, is a bal-
ance between the pure and impure, and slight changes in the form of
sediment result in deterioration or better quality. Such changes are
common in most sediments and must be expected in quarrying the
marble. Not only may a good bed become poor, but a poor bed may
develop into good marble.
Tests for absorption of water show a high resistance in the better
grades of marble, and the rock is very well fitted for withstanding
weather. Its crushing strength is also very high in the purer layers.
Tests of a number of samples gave an average strength of 10,000
pounds per square inch.
368 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 11)02. [mux. 213
The nature and associations of this marble are subject to great
variations. An instance of this is the disappearance of red marble
northeast of Thorn Hill in the belt running north of Clinch Mountain,
its place being taken by blue and gray marbles. These latter beds
are of good body, but lack the most prized color. More marked!
changes are seen in the disappearance of the massive marble and the
increase of shale in the same belt after it passes southwest from Lut-
trell. Similar changes are seen east and south of McMillan and
Strawberry Plains. The position of the marble in the Chickamauga
limestone also varies. Near the northeast end of Black Oak Ridge,
and also northeast from Luttrell, the Chickamauga limestone appears
only above the marble. Along Holston River, however, the limestone
appears only below the marble, above the latter being the Tellico
sandstone. In other places the marble occupies an intermediate posi-
tion. In the next basin north of the Clinch syneline no marble
appears except northeast of Maynardville, where some unimportant
beds of gray marble occur. North and west of this no marble has
been observed, nor does any of consequence occur along the southern
border of the Maynardville quadrangle.
The marble above the Tellico sandstone in the base of the Sevier
shale is comparatively thin and shaly. Occasionally, however, a
local thickening takes place and the beds resemble the Holston marble
in all respects. This is notably the case in the area of Sevier shale
extending southwest from Strawberry Plains past Knoxville. The
Sevier marble beds are much more variable than those of the Chicka-
mauga, and there is a smaller amount of workable material in them; !
consequently they have not been successfully quarried.
Other variations in the marble are shown in the disappearance of
good marble for a few miles in the belt running through the northern
portion of Knoxville. The belt which is productive south of Knox-
ville becomes of minor importance 8 miles northeast of Knoxville; and
the bed at the bottom of the Sevier shale is the productive one in that
locality. These latter marbles in the region of Knoxville are usually
shaly and of less value, although they contain many beds of good body
and color. Workable beds are rarely over 10 feet thick, and usually
there are several varieties in close proximity.
Southwest of Knoxville the Holston marble varies in similar fashion.
It disappears in the belt northwest of Madisonville and shifts down-
ward into the beds next to the Knox dolomite at Marble Bluff, west
of Loudon. As a rule, however, the marble in this region remains
very constantly in the upper part of the Chickamauga limestone.
The different belts continue south westward to the vicinity of Sweet-
water. They then disappear rather abruptly and are not found in
areas farther southwest.
The marbles of the Sevier shale are prominent at the bottom of that
formation, but occasionally occur in the upper strata as well. They
th.] TENNESSEE MARBLES. 369
ire similar to the Chickamauga marbles, but usually have not such
•ich colors, being oftenest of a gray color; and they contain more
jhaly beds. The belts passing south of Loudon and Louisville have
this marble more highly developed than the other belts. It has been
quarried only in the southeastern belt, near Mountain ville, and farther
southward at the Tellico River, and its beds are not now worked, for
want of transportation facilities. These marbles extend a little farther
southwest than the Holston marble.
QUARRY LOCATIONS.
Owing to the soluble nature of the pure marble, it is either com-
pletely unaltered and fresh or it is entirely reduced to red clay. The
best marbles, therefore, are nearly as solid at the surface as at great
depths. Marbles which are shaly at the surf ace become less weathered
in going down, and appear solid; but when these are sawed and
exposed to the weather their inferiority appears in splits along the
argillaceous seams and in cracks through the thicker masses. Solu-
tion of the pure beds has produced holes and eaves down to the adja-
cent stream levels. Through these openings the quarry men attack
the rock more easily, but much valuable stone has been lost by
solution.
The available localities for quarrying are limited in part by the atti-
tude of the marble beds. At the northeast end of the marble belt
the best situations are those just north and northwest of Rogersville,
where the strata dip at a high angle and there is little stripping to be
done. Here the location of the marble, well above drainage, is an
added advantage. In the areas north of Clinch Mountain the dip is
such as to carry the marble beneath the surface with narrow out-
crops, but is not steep enough to avoid considerable stripping.
In the same belt southwest of Clinch Mountain the dip is usually
steep, so that the amount or earth to be stripped is not great. Near
Holston River, owing to the recent cutting of the streams, the marble
is usually at some distance above the water level. In the more north-
ern areas, where the streams have not cut their valleys deeply, the
marble usually occupies the lowest portions of the valleys, being the
most soluble of the formations, and the drainage of the quarry becomes
an important problem. This is also the case even in areas well above
drainage level, when springs and underground streams are encoun-
tered, as frequently happens.
The best situations are those in the belt immediately south of Knox-
ville, where the strata dip at small angles and cover a greater surface.
Most of the marble is well above the drainage level. Similar advan-
tages of dip favor the belt 5 miles northwest of Knoxville. In most
of the areas of marble southeast of Knoxville the beds are more folded
and dip at greater angles, so that prolonged quarrying will necessitate
a great deal of stripping and deep cutting.
Bull. 213—03 24
370 CONTBIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
Iii the extension of the marbles southwest of Knoxville line quarry
sites are to be found 10 or 12 miles from Knoxville. In that vicinity
the strata dip at small angles and cover a great surface. Conditions
of drainage are also excellent there. In most of the other areas of
marble the beds are more folded and dip at greater angles, so that
prolonged quarrying will necessitate a great deal of stripping. Also,
in districts far from the Tennessee River, the marble is likely to be in
low ground, so that quarries would be near the drainage level. At
present the great bulk of marble quarried comes from the vicinity of
Knoxville. It is here well situated with respect to transportation over
different railroads, besides being of the best quality. Good marble
exists in immense quantities, however, in the other regions, and will
become available as more favorable places are exhausted, as new means
of transportation are found, or as the fashion in color changes.
GEOLOGICAL SURVEY PUBLICATIONS ON STONE.
Bain, H. F. Notes on Iowa building stones. In Sixteenth Ann. Rept., Pt. IV,
| pp. 500-503. 1895.
Dale, T. Nelson. The slate belt of eastern New York and western Vermont.
In Nineteenth Ann. Rept,. Pt. Ill, pp. 153-200. 1899.
Hillebrand, W. F. Chemical notes on the composition of the roofing slates
of eastern New York and western Vermont. In Nineteenth Ann. Rept., Pt. Ill,
pp. 301-305. 1899.
Hopkins, T. C. The sandstones of western Indiana. In Seventeenth Ann.
Rept., Pt. Ill, pp. 780-787. 1896.
Brownstones of Pennsylvania. In Eighteenth Ann. Rept., Pt. V, pp.
1025-1043. 1897.
Hopkins, T. C, and Siebenthal, C. E. The Bedford oolitic limestone of
Indiana, In Eighteenth Ann. Rept., Pt. V, pp. 1050-1057. 1897.
Ries, H. The limestone quarries of eastern New York, western Vermont,
Massachusetts, and Connecticut. In Seventeenth Ann. Rept., Pt. Ill, pp. 795-811.
Shaler, N. S. Preliminary report on the geology of the common roads of the
United States. In Fifteenth Ann. Rept., pp. 259-306. 1895.
The geology of the road-bnilding stones of Massachusetts, with some
consideration of similar materials from other parts of the United States. In
Sixteenth Ann. Rept., Pt. II, pp. 277-341. 1895.
Siebenthal, C. E. The Bedford oolitic limestone [Indiana]. In Nineteenth
Ann. Rept., Pt. VI, pp. 292-296. 1898.
371
CEMENTS.
During the forthcoming field season all the important cement plants
in the country will be visited, and a report on the cement industry in
the United States will he published by the Survey.
In addition to the paper presented below, a discussion of slag
cements will be found on pages 221 to 223 of the present bulletin;
while the manufacture of Portland cement from slag is discussed on
pages 223 to 224.
CEMENT INVESTIGATIONS IN ARIZONA.
By Edward Duryee.
INTRODUCTION.
Investigations were made under instructions from Mr. J. B. Lippin-
cott, of the U. S. Geological Survey, in order to ascertain means of
lessening the cost of Portland cement in the construction of dams on
the Gila River in Arizona. Owing to the remoteness of these pro-
posed dams from lines of transportation, the expense of bringing
cement to the sites makes a notable addition to the cost over con-
struction elsewhere, and it is therefore of great importance to reduce
the quantity of cement to the smallest allowable amount.
Portland cement is considered an essential element in the construc-
tion of dams subject to severe and sudden strains due to floods. It
is valuable not only in giving great strength and homogeneity to the
structure, but also because of the fact that exposure to moisture,
which deteriorates many materials, serves to increase the strength of
Portland-cement mortars. It is thus being largely used for this pur-
pose. For example, the new dam under construction on the Nile at
Assuan will require 3,000,000 barrels of Portland cement, costing, in
round numbers, $12,000,000.
The investigation of cement for the Gila River dams has been
along three lines: (1) To ascertain whether by unusually fine grinding
of the cement its strength can be appreciably enhanced and the
quantity correspondingly reduced ; (2) whether it is feasible to use
the rocks found at the dam sites for making a sand cement; (3)
whether Portland cement can be economically made at these sites.
372
ditryek] CEMENT INVESTIGATIONS IN ARIZONA. 373
SAND CEMENT.
Sand cement is a term applied to a mixture of cement and sand
ground together in a dry state to an impalpable powder. As a rule
Portland cement and quartz sand are the materials thus used. This
mixture is then used with ordinary sand and gravel, as in the cus-
tomary practice. The proportion of pure cement is thus considerably
reduced, but the strength and durability of the concrete has been
found to be nearly as great as that made with the undiluted cement.
The explanation offered for the remarkably good results obtained
with sand cement when used with ordinary coarse sand is that the
voids in the coarse sand are nearly filled with the finely ground sand.
The grains are thus bonded together and to the coarse sand by the
uniformly diffused particles of the fine cement. The amount of voids
in the ordinary sand, in other words, is greatly reduced by the fine
sand, fulfilling the requirement for a strong mortar that must be of
dense character, the grains being of such graduated size and so
well mingled as to afford the maximum contact of the surfaces of the
particles.
In sand-cement mortar the grains of sand are extremely minute,
the mixture being so fine that only 5 per cent residue is left on a
screen of 200 meshes to the linear inch or 40,000 meshes to the square
inch. The great density thus obtained contributes to the imperme-
ability to water and increases the compressive strength and load-
bearing capacity, thus rendering the mass of value for constructing
foundations, dams, and sea walls.
In the tests made in this investigation a rock known as pearlite, an
acidic lava or rhyolite from the Buttes dam site, was used, and also
samples of quartzite from the San Carlos dam site. These were chosen
because of the abundance of these rocks at the localities named and
their superior hardness. The Portland cement used was that manu-
factured at Colton, Cal., this being made nearest to the place where
it will be used and being sold at a lower price than other Portland
cement in the local market. All of the tests were made with the
same sample of cement, portions of this being taken for the several
mixtures with cruahed pearlite and quartzite. The sand used with
the foreign cement in making sand cement was clean beach sand from
dunes along the coast.
TESTS OF SAND CEMENTS.
Results of the tests of the sand cements and comparisons with other
mixtures are given in the following table. In each case the crushed
pearlite was mixed with an equal weight of cement, and the mixture
was ground in a mortar until it all passed through a screen having 200
meshes to the linear inch. The same method was pursued with the
quai'tzite from San Carlos, thus making sand cements composed of
equal parts of Portland cement and pulverized rock ground to an
exceedingly fine condition.
374
CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902.
[hum, .213.
The coarse sand used in making the mortar with the sand cement
and with the pure (Portland) Colton cement was of the ordinary grade
of fineness used for making cement tests. It was screened from ordi-
nary gravel, all residue. on the 20-mesh screen being rejected and all
left on the 30-mesh screen being retained.
The briquettes for testing were made according to the specifications
recommended by the American Society of Civil Engineers. After the
briquettes were made they were kept under a damp cloth for twenty-
four hours, then placed in vats of water, where they were left until
the time for breaking arrived, namely, seven days or twenty-eight
days. The fine grinding and diluting of the Portland cement with
fine sand did not materially affect the time of hardening or setting.
The beginning of the setting process of the ordinary Colton cement
mortar, or initial setting, was thirty-three minutes, and the time of
final setting was eighty-five minutes. This applies to samples Nos.
3, 4, and 9 of the following list. The corresponding periods for the
sand cement were thirty and eighty minutes. The cement mortar
continues to harden and increase in firmness for a year or longer.
Results of tests of Port/mid saml cements.
No.
Material.
( nit on and Buttos pearlite, 1
tol.
( !olton and San Carlos quartz-
ite, 1 tol
Colton, regular
do
Colton, fine ground.
do
Sand.
Colton and Butte pearlite,
tol..
< !( ilt i .li and San Carlos quartz-
ite, 1 to 1
( tolton, regular
Imported
Imported and sand, 1 to 1
....do
....do
....do...
Imported, regular
....do
Port-
land
cement
to
sand.
Fineness
Water.
50
mesh.
L00
mesh.
200
mesh.
Per ct.
Perct.
Per ct.
Per ct.
1 to 5
0.00
0.00
0.00
10
1 to5
.1X1
.(H)
.(H)
Hi
1 to 2
. 42
7.20
33.20
in
1 to3
. 42
7.20
33.20
10
1 to 2
.00
.(H)
(a)
L2
1 to3
.(HI
.(HI
(a)
L2
1 to 7
.00
.(H)
.00
10
l in;
.00
.00
.00
10
l toO
.42
7.20
33.20
IS
1 toO
.80
7.80
29. 33
IS
1 to 5
.(H)
.(H)
.(H)
1(1
1 to5
.(HI
.(H)
(a)
10
Lto7
.(H)
.(HI
(a)
10
1 to 7
.(H)
.(H)
.(H)
10
1 to 2
.80
7.80
29.33
10
lto3
.80
7. SO
29.33
10
Strength.
1 days.
/As',
so
90
170
140
370
170
615
345
li:,
L25
55
90
210
L20
28
days.
Lbs.
300
34")
385
240
465
260
185
Of ill
525
11)0
1S5
(.M)
140
270
175
«Some left on 200-mesh screen.
Note.— The above cement stood the boiling test for free lime satisfactorily.
Comparison of test No. 3 with No. 5, and of No. 4 with No. 0, shows
that increased fineness of grinding very materially increases the
strength and sand-carrying capacity of cements. The ordinary Col-
ton cement of tests No. 3 and No. 4 was ground finer than commercial
Portland is usually ground. Recent improvements in mills for grind-
CEMENT INVESTIGATIONS IN ARIZONA.
375
ing render possible a reduction in size of cement grains at a cost
which is small when compared with the great increase in the value of
jithe resulting material. Where the freight charges are high, as is the
ase at the locations under consideration, it is especially important
to take advantage of this improvement, and there is no doubt that if
the specifications call for a fineness such that only 1 per cent is to be
left on a 100-mesh screen, the manufacturers will respond to the
requirements. Engineering specifications have ordinarily allowed a
residue of 5 per cent on a 50-mesh screen, although manufacturers
have for some years permitted a residue of only 1 or 2 per cent on a
50-mesh screen.
CRUSHING TESTS.
In order to obtain the crushing strength of the various cements and
concrete considered, two 1-inch cubes of each were broken. The
results given are the averages of the crushing strength of the two
cubes. The cubes were allowed to remain thirty days in water and
then thirty days in the air.
Crushing tests of l-inch rubes.
Character of mixture.
Water.
Average
crushing
strength.
Standard C< >lton cement
Colton cement. 1 part, and ordinary testing sand, 3 parts _
Col ton cement, 1 part, and marble sand, 2 parts
Per cent.
IS
8
8
Tons.
3.25
1.75
2.38
Crushing tests were also made of 0-inch cubes of concrete after
these had been immersed for thirty days in water. The portions of
the mixture and the breaking strain in tons are given in the follow-
ing table. In the mixture the proportions are given by volume and
not by weight.
Crushing tests of 6-inch cubes.
Character of mixture.
Colton cement, 1 part; ordinary sand, 3 parts; pebbles from gravel, 6 parts.
Colton cement, 1 part: sand, 3 parts; crushed marble, 6 parts
Colton cement. 1 part; sand. 2 parts; crushed marble, 5 parts
Breaking
strength.
Tons.
38
30
20
It is believed that concretes of approximately equal value can be
obtained by using cements in the following proportions, measured by
volume:
Portland cement, 1; sand. 3; broken stone, 7.
Sand cement, 1; sand, 2; broken stone, 6,
376 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bum. 313.
COST OF SAND CEMENTS.
In the Portland -cement concrete made in the proportion of cement
1 part, sand 3 parts, and broken stone 7 parts, it has been found that
270 pounds of cement will be required for a cubic yard of concrete.
This, at 2.12 cents per pound, will cost $5.72 per cubic yard.
In the sand-cement concrete of the proportions 1 cement, 2 sand,
and 6 stone, 340 pounds of cement would be required for each cubic
yard of concrete. This, at 1.2 cents per pound, would cost $4.08.
The saving in the cost of cement to be effected by using sand
cement instead of the Colton .Portland will be the difference between !
$5.72 and $4.08, or $1.64 per cubic yard of this concrete entering into
the construction of the dam. From the total saving thus realized
should, however, be deducted the cost of the plant required for grind-
ing the sand cement.
Concrete blocks composed of the above proportions were crushed at
McGill University in 1898, with the following results:
Sand cement, 1; sand, 2; broken stone, 6; water, 20 per cent.
Weight per cubic foot, 154 pounds. Crushing load, in pounds per square inch:
Seven days, 521 pounds; twenty-eight days, 639 pounds; sixty days, 670 pounds.
A concrete of German Portland of the proportions of 1 cement, 2
sand, () broken stone, and 20 per cent water stood a load of 728 pounds
per square inch in twenty-eight days, and one of the same proportions
made from English Portland stood 698 pounds in twenty-eight days.
Tests for crushing strength on 6-inch cubes of concrete, made of 1
part sand cement, 2 sand, and 3 parts gravel, were made on concrete
that was taken from the bucket just as it was ready to be laid in the
foundation of the Cathedral of St. John the Divine, in New York
City. Each result is the average of the crushing strength of four
separate cubes, made under exactly the same conditions at different
periods:
Pounds.
7 days old crushed at 77,162
1 4 days old crushed at 83, 225
30 days old crushed at 92,465
Approximate cost of plant for making smut cement; capacity, 2^0 barrels per
twenty-four hours.
Crusher (required also for crushing rock for concrete) .... $2, 000. 00
Mill for coarse grinding . . : 2, 000. 00
Tube mill for finishing . _ 2, 500. 00
Engine and boiler '_ 1, 500. 00
Setting up machinery . 1, 000. 00
Buildings and bins 1, 000. 00
Total , _ •_._.. : 10, 000. 00
Cost of mill per barrel of cement .20
Add, for concrete making, a power mixing machine 1 , 500. 00
In making concrete, if a good quality of stone be used and the rock
be crushed so as to be well graduated as to sizes, thus securing a min-
kvkk.I CEMENT INVESTIGATIONS IN ARIZONA. 377
imum of voids, the compressive strength of the concrete increases as
the proportion of stone increases and as the volume of voids between
the stone decreases, and decreases as the proportion of sand in the
mortar increases. The rule, therefore, holds: to secure the greatest
strength mix the maximum quantity of stone with a minimum of
sand mortar sufficient to bond the stone together, the sand mortar
being rich in cement. An extensive bed of exceptionally good sand
for mortar was found near the Buttes, the grains graduating in size
from very small to large sizes. It shows only 35 per cent of voids,
while the standard cement-testing sand used in laboratories has 45
per cent of voids.
A large tube mill will grind 10 barrels of sand cement per hour to
the requisite degree of fineness, at an estimated cost of 20 cents per
barrel. The cost of power for grinding is calculated at 3 cents per
horsepower per hour at the dam site.
( 'ost of sand cement with Portland cement at ss per barrel.
One-half barrel. Portland $4. 00
One-half barrel crushed and coarse-ground qnartzite . .18
Grinding same in a tube mill ... .20
Royalty on account of sand-cement patent .05
Total cost of sand cement per barrel (375 pounds) : 4. 43
The cost of sand cement per pound, qnartzite being used as the
source of the sand cement, would therefore be 1.2 cents.
The cost of the mill per barrel of cement, 20 cents, is not included
in the above.
It is estimated that the cost per barrel of Colton Portia cement
delivered at the dam site will be $8. This, for 375 pounds weight
cement, would make the cement cost 2.12 cents per pound.
USE OF ROCKS AT THE DAM SITES.
For the purpose of ascertaining whether the rocks at the dam sites
could be used in the manufacture of Portland cement the localities
were visited and samples were obtained of those rocks which occurred
in sufficient quantities to furnish the supply necessary for manufac-
turing the large amounts of cement needed. In looking for the raw
materials it must be borne in mind that, chemically considered, Port-
land cement consists of a compound of tricalcium silicate and dical-
cium aluminate, accompanied by small percentages of ferrate and
sulphate of lime and traces of alkalies. It is made by grinding and
burning together either natural or artificial mixtures of carbonate of
lime and silicate of alumina. Limestones, chalks, or mails usually
furnish the carbonate of lime, and clays are the ordinary source of
the alumina and silica. The mixtures are burned at a high tempera-
ture to a blackish clinker of a semivitrihed character. After cooling,
this clinker is reduced by grinding loan impalpable powder, in which
form it is known by the generic name of Portland cement.
378
CONTRIBUTIONS TO ECONOMIC GEOLOGTY, 1902. [bull, zd
ROCKS AT RIVERSIDE DAM SITE.
Limestone (No. 3 in the following table) was obtained near River-
side, on the road to the Pioneer mill, where it is found in large quan-
tities along the roadside. The rhyolite (No. 4 in the following table)
was found 2 miles south of the Riverside site. It offered the closest
approach to a suitable silicate of alumina that could be found.
The source of elements of silica and alumina in the crude materials
should, however, be sedimentary in character, not igneous or meta-
morphic. The analysis justified a trial mixture, and therefore one
was calculated and made, but on burning the materials failed to
effect the requisite combination for a Portland cement. Too large a
percentage of the silica was in the free or uncombined condition.
Fuel was not to be found near the Riverside site, and the manufac-
ture of cement at this place is considered impracticable.
ROCKS AT SAN CARLOS DAM SITE.
The limestone from San Carlos site (No. 2 in the following table)
was found to be admirably adapted to the purpose of the dam con-
struction on account of its good specific gravity (which was 2.7),
freedom from flaws, and siliceous character. It occurs in vast quan-
tities, forming the abutments of the dam site. It forms bluffs,
extending for several hundred feet, well located for quarrying. Large
masses ma)7 be embedded in the concrete, care being taken that they
be laid irregularly in the mass of the dam, and are well placed so as
to bond into a monolith.
Analyses of rocks from I he vicinity of flic dam sites.
[Chemical composition, in percentages. ]
No.
Name.
Color.
Locality.
Sp. gr;
Car-
bonate
of lime,
CaCO.j.
Car-
bonate
of mag-
nesia.
Silica
(SiOo).
Alu-
min-i
and
ferric
oxide.
Mois-
ture.
0.65
1.00
16.90
Lime
per
cent in
the
car-
bonate
of lime.
1 Limestone _
Gray...
Pink . . .
Blue....
White..
Pearl.
Blue....
Gray . . _
96. 65
55. 92
93.10
9. 60
0.00
31.00
(UN)
1.4
3.7
4.7
60.9
1.3
6.0
1.4
12.6
54. 124
2 j do
3 do...
do
Riverside
2.7(1!!
31.315
52. 13(5
4
5
Rhyolite
do
Limestone..
do ! 1.541
Buttes i 2.3(51
5. 376
6
90. 10
55. 50
0. 00
0.00
4.1
34.6
5.8
7 do.
do
2.678
1.3
31.08
From about U miles above dam site.
The analysis of the gray or bluish limestone (No. 1 in the above
table) shows from its freedom from magnesia and the small percent-
age of free silica that it is possible to make a Portland cement with
it, provided a suitable clay can be found to furnish the requisite
elements of silica, alumina, and ferric oxide.
duryee] CEMENT INVESTIGATIONS IN ARIZONA. 379
FUEL.
An extensive but undeveloped deposit of bituminous coal is located
about 17 miles from the San Carlos dam site. There is a wagon trail
to within about G miles of the coal beds, but after leaving the wagon
trail the only means of access was found to be a bridle path over the
hills. About ten years ago numerous prospectors' locations were
made in the district, and shafts were sunk at a sufficient number of
localities to prove the deposit to be of considerable extent. Most of
the shafts have become filled with debris, but several were entered to
depths of 15 to 30 feet. Tlw showed the body of coal to be in beds
having a dip of about 60°, the beds being from 5 to 10 feet in thick-
ness, not of solid fuel, but showing seams of good coal interlaid with
seams of slate and waste. In the bottom of the deepest shafts was
found a good body of coal in a solid bed perhaps 5 feet thick. It was
reported that at the time the prospecting was done on the claims some
30 tons were transported by wagons to the Southern Pacific Railroad
and used in the locomotives, but that the cost of mining and trans-
porting it to the railroad, with the crude means available at the time,
was about $20 per ton.
Cement could be burned with the coal. The right to mine the coal
for the use of the Government in this work could be secured readily
and at a nominal cost. The cost of mining and transportation to San
Carlos would, however, be high. In general practice 120 pounds of
coal dust are used in burning 1 barrel of Portland cement.
Taking as a basis coal delivered at the dam site at $10 per ton,
limestone at 40 cents per ton, and clay at $1.25 per ton, the cost of
manufacturing Portland cement at the dam site would approximate
$2.75 per barrel. The cost of erecting a plant with an output of 300
barrels of cement every twenty-four hours would be $75,000. Sup-
posing the amount of cement to be required in the construction of
the dam to be 50,000 barrels, the cost per barrel, if made at the site,
would be approximately as follows: First cost of plant, $75,000; cost
of manufacturing 50,000 barrels, at $2.75, $137,500; total cost,
$212,500; cost per barrel, $4.25.
With reference to the degree of reliability to be placed upon Port-
land cement made in new localities, it may be said that the manufac-
ture of this material has been put upon a scientific basis, such that
the manufacturing chemist can predict the grade of cement to be
made from the given materials, and, by means of analyses of various
rocks, can calculate suitable mixtures to produce the required result.
The uniform system of testing cements recommended by the Ameri-
can Society of Civil Engineers affords a reliable means of determining
the intrinsic merits of the product. The old method of buying
cements on the reputation of the maker has been succeeded by tests
for determining the actual value. Portland cements of American
380 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
make are being extensively manufactured and are of equal or even'
superior quality to the foreign-made cements. During the year 1890
it is estimated that 0,000,000 barrels of Portland cement have been
used, of which four-fifths were of home manufacture. In spite of
this fact, on account of the failure to find suitable clays at the various
localities and also the difficulty of obtaining fuel, it is impracticable
to manufacture Portland cement at the dam sites.
It is important, if Portland cement is used at the localities under
consideration, that the specifications should require it to be ground
so fine that not over 1 per cent residue shall remain on a 100-mesh
screen.
Reliable sand cement can be made from the quartzite at San Carlos
or the pearlite at the Buttes dam site by grinding with Colton (Port-
land) cement. A saving will result at the San Carlos dam site of $1.64
per cubic yard by making sand cement on the ground, this being
exclusive of the cost of the plant for grinding.
PUBLICATIONS ON CEMENTS.
The following list includes the principal publications by the United
States Geological Survey, or by members of its staff, on cementing
materials.
Cummings, U. American rock cement. A series of annual articles on natural
cements, appearing in the volumes of the Mineral Resources, U. S., previous to
that for 1901.
Eckel, E. C. Slag cement in Alabama. In Mineral Resources for 1900,
pp. 747-748. 1901.
The manufacture of slag cement. In Mineral Industry, Vol. X. pp.
84-95. 1902.
Newberry, S. B. Portland cement. A series of annual articles on Portland
cements, appearing in the various volumes of the Mineral Resources, U. S., pre-
vious to that for 1901.
Russell, I. C. The Portland cement industry in Michigan. In Twenty-second
Ann. Rept. U. S. Geol. Survey, Pt. Ill, pp. 629-686. 1902.
Taff, J. A. Chalk of southwestern Arkansas, with notes on its adaptability to
the manufacture of hydraulic cements. In Twenty-second Ann. Rept. U. S. Geol.
Survey, Pt. Ill, pp. 687-742. 1902.
381
CLAYS AND FULLER'S EARTH.
The clays of the eastern United States will be the subject of a bul-
letin to be issued by the United States Geological Survey during the
present year. Owing to its comprehensive character, no abstract of
this important work has been attempted for the present publication.
The results of recent field work by the Survey on the clays of western
Tennessee and northwestern Mississippi, and on the fuller's-earth
deposits of Florida and Georgia, are given in the following papers:
STONEWARE AND BRICK CLAYS OF WESTERN TENNESSEE AND
NORTHWESTERN MISSISSIPPI.
Bv Edwin C. Eckel.
INTRODUCTION.
A preliminary report on the clay resources and industries of this
region is here presented. Owing to the short time available for the
field work, the writer's investigations were practically confined to an
examination of the stoneware clays of the area. A few plants mak-
ing common brick were visited, and notes on this industry have been
appended.
STONEWARE CLAYS AND MANUFACTURE.
The stoneware clays of the region under discussion appear at the
surface of a belt of country averaging 10 miles or more in width and
extending from Holly Springs, Miss., through Grand Junction, Jack-
son, and Paris, Tenn., into Kentucky. No field work was done on
1 hese clays south of Holly Springs or north of the Kentucky-Tennessee
line, though the clays are known to be of economic importance both
south and north of these limits.
The age of the clays has been discussed by Safford, Ililgard, Lough-
ridge, Smith, and McGee, the principal question at issue being whether
or not they are to be included in the Lafayette. While the work of
the present writer can not be regarded as conclusive, certain facts of
interest have been developed. As described by McGee, the series
shown in this area, from the top downward, is as follows:
1. Columbia brown loam.
2. Lafayette orange sands.
3. Lafayette (stoneware) clays.
382
bckel.] CLAYS OF TENNESSEE AND MISSISSIPPI. 383
There seems to be no doubt about the order of this series, but
from the examination of a large number of exposures it would seem
probable that a very marked geologic break occurs between- the orange
sands and the stoneware clays. The stoneware clays are normally
accompanied by and interbedded with a series of fine white and light
yellow sands, commonly ver}r thinly and evenly bedded. At a few pits
the contact between the clays (and interbedded sands) and the orange
sands of the Lafayette seemed regular and conformable, but in most
places, notably near Grand Junction, very marked erosion appears to
have taken place before the deposition of the orange sands.
A few of the pits visited near Pinson and Paris seem to have pene-
trated to a horizon lower than that of the stoneware clays. The pits
in question produce a very dark, lignitic clay, used in places as a ball
clay. It seems probable that these dark-colored ball clays are of Lig-
nitic (Tertiary) age.
The claj^s used in the stoneware industry are in general obtainable in
clean masses, free from (extraneous) sand and gravel. So far as known
no mechanical analyses of these clays have been made, so that it can
not be ascertained just how much of their silica is really present as
fine sand and chert. The fusing point of the clays is very high, and is
proved by the fact that most of the potteries use, in addition to the
usual Albany slip clay, slip clay from Seneca Falls, N. Y., or slips
made up from feldspar and quartz. As both these latter fuse only at
a high temperature, their use proves the relative inf usibility of the
stoneware clays.
Many improvements in the stoneware industry in this district are
possible. First of all, the method — or lack of method — in excavat-
ing is very wasteful and extravagant. By s}Tstematic work all the
clay in the banks could be extracted, and that at a lower cost per ton
than now obtains. In some cases observed the selection of spots in
which to work is left entirety to the caprice of the negroes who do the
digging, and in consequence the area is covered with small pits. As
soon as these become inconveniently deep another excavation is started
in another place. The stripping, when there is any, is thrown care-
lessly to one side, thereby covering up and rendering useless a cer-
tain amount of clay.
In the second place, it would seem advisable to season the clays
somewhat, instead of sending them direct from the pit to the mill.
By a little extra care, which might necessitate supervision of the
negroes working the clay pits, the average quality of the material
sent to the mill could be raised. Frequently the mixture of clays
from different pits would greatly improve the product. Finally, it
would seem advisable to push the fire-brick industry in every possible
way. At present this product is manufactured on a very small scale,
and little attention is devoted to the technology of the subject. It
seems probable that it is in this direction, rather than in the line of
stoneware, that the clay industry of the district will progress.
384 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
The clay pits and stoneware plants visited will be described in order,
from those near Holly Springs, Miss., at the south, to those near Paris,
Tenn. , at the north.
HOLLY SPRINGS, MARSHALL COUNTY, MISS.
The plant of the Holly Springs Stoneware and Firebrick Company
is located near the tracks of the Kansas City, Memphis and Birming-
ham Railroad, and within 100 yards of the station. Little fire brick
is made, the principal product being stoneware. The clay used at
this plant is obtained from the pits described below. On arrival at
the works it is ground, after the addition of sufficient water, in a
"chaser mill" (i. e., edge-runner mill), no seasoning at all being given
the clay. Four kilns are in use, two downdraf fc and two updraft, the
former having been, of course, installed at a later date than the latter.
Eighteen hands are employed in the plant, four of whom are potters;
and the product of the establishment is about 8,000 "gallons" of
stoneware per week. Two slips are used. One is the usual Albany
slip clay, which gives a brown glaze, the other a slip made up of
"flint" (pulverized quartz) and "spar" (pulverized feldspar), both
the ingredients being purchased at East St. Louis.
The clay pits of this firm are in two widely separated groups, located
2^ miles west and 1 mile east of the railroad station.
The west pits furnish the best grade of clay. About 05 acres of
land are owned (on which these west pits are located). Of this area
about 10 acres have been worked in the usual fashion.
The usual size of these pits is 8 to 10 feet in depth, with an area of
from 4 by 6 to 8 by 15 feet. One negro with one team of horses does
the hauling. Three trips a day can be made.
No Lafayette (orange-red sands) was in this area. A typical pit
showed from the top downward —
Feet.
Clayey and sandy soil 3
Yellow sand and clay in alternate 2-4 inch hands 3
Gray clay 6
The eastern pits, located a mile east of the station, show (in pits
and gullies) about 20 feet of clay, with much interlami nation of white
and yellow sands. Six trips per day can be made to these pits.
Peyton Allison runs a small pottery, with one updraft kiln, about
one-half mile east of the station, obtaining his clay from very near
the east pits of the preceding firm.
GRAND JUNCTION, HARDEMAN COUNTY, TENN.
The plant of the Grand Junction Potter}?- Company, controlled by
Mr. W. T. Follis, is located near the station. Clay is bought from
various pits in the vicinity and manufactured mostly into stoneware,
though fire brick is occasionally made. One downdraft kiln, with a
capacity of 6,000 gallons of stoneware, is in use.
eckei,.] CLAYS OF TENNESSEE AND MISSISSIPPI. 385
The Hancock pits are located three-fourths of a mile southwest of
town, reaching for several hundred yards along both sides of the Illi-
nois Central tracks. The clay begins to ontcrop about 200 feet south
of the Fayette-Hardeman county line, and the deposits therefore lie
in Fayette County. These pits are worked occasionally to supply
the local pottery noted above, but were idle at the time of visit. The
iclay is said to be the best obtainable near Grand Junction. The sec-
tion shows orange-red sands above, belonging to the Lafayette for-
mation. The lower 6 inches to 4 feet of these sands have been
cemented into a conglomerate hy infiltrating waters carrying iron.
Below the sands is exposed 20 feet or more of clay, which is light gray
on a fresh surface, but weathers, on exposure, to a chalky white.
The clay contains no apparent partings of sand. At this point the
top of the clay beds is jnst at the level of the railroad tracks.
The extensive pits of the Irwin Clay and Sand Company are located
1^ miles east of the station, along the south side of the Southern Rail-
way tracks. These pits were opened in April, 1901. Little has been
done with the clay, but extensive shipments of sand have been made.
The pits are about 60 feet below the track level, the material being
brought up on an inclined tramway. Several small pits, filled with
water at the time of visit, had been sunk below the level of the main
excavation. The complete section from the top of the bank down,
including the section reported as appearing in these small pits, is as
follows :
Section of Irwin clay bank, Grand Junction, Tenn.
Red sand 40 feet (to top of bank) .
White sand, evenly stratified 8 feet.
White clay 8 feet.
Gray, lignitic, clay 8 inches to 10 inches.
White clay 20 inches.
White sand 1 foot (to bottom of deepest pit) .
The clay deposits, as seen at this extensive series of exposures, are
very irregular, and apparently occur as overlapping lenses in the
white and yellow sands. The overlying red sands of the Lafayette
formation would seem to have been deposited after extensive erosion
had taken place in the clay and white sand series.
Three-fourths of a mile west of Grand Junction station are located
the clay pits of Mr. J. H. Prewitt, at a point about 200 yards north of
the Southern Railway tracks. The clay is said to be of good quality,
though carrying somewhat more iron than does that from the Hancock
pits. The excavations are small, only about 10 feet or so of clay
being shown. The clay is overlain immediately by a dull brown
loam (Columbia formation), the red sands of the Lafayette being
absent.
The Stinson pits are small openings located on the south side of the
Southern Railway tracks, about one-half mile west of Grand Junction
Bull. 213—03 25
386 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
station. The clay is said to be as good, if not better, than that from
the Prewitt pits.
Stoneware clays of the same general type as those described above
are well exposed, and have been worked rather extensively, near
Lagrange, 3" miles west of Grand Junction. About 5 miles east of
Grand Junction, at Saulsbury, clay is also worked; but the material
from this locality may be the dark-colored ball clay (of the Lignitic
Tertiary), described later as occurring in a belt bordering the stone-
ware-clay region on the east and outcropping near Pinson and Paris,
Tenn.
TOONE, HARDEMAN COUNTY, TENN.
A large pottery located at this point could not be visited during the
course of field work, and no information concerning it was obtainable
by correspondence.
PINSON, MADISON . COUNTY, TENN.
A large pottery located near Pinson station is operated by Messrs.
Robins and Henderson. The plant, which is run entirely by steam,
is by far the best equipped that was seen on this trip. Fire brick,
tiles, and stoneware are manufactured, and, to a small extent, com-
mon brick. The engine supplies about 35 horsepower to the plant.
It should be recollected that usually pari of the machinery is idle, as
it is but rarely that both stoneware and fire brick are in process of
manufacture.
The clay for stoneware passes through the following processes in
order:
1. Crushing (crusher).
2. Grinding (wheel).
3. Turning (hand work, wheel run by steam).
4. Drying (on heater).
5. Burning.
The kiln used is down draft of the Stewart pattern, the rights being
owned by the Stewart Patent Kiln Company, of Findlay, Ohio. The
right to erects one kiln costs $100. It is fired entirely with wood.
One burning requires about 15 cords, costing here about $1.50 per
cord. The production of stoneware is about 2,500 gallons per day.
The same clay is used for fire brick, in which case it passes through
the following machines:
1. Disintegrator.
2. Pug mill.
3. Brick machine. *
The mixture used for fire brick- is —
3 parts clay.
1 part white sand.
1 part sawdust.
ECKKb.J CLAYS OF TENNESSEE AND MISSISSIPPI. 387
The mixing is effected in the disintegrator. The brick machine
requires 8 men to operate it, as follows: 2 " off-bearer," 1 "take off,"
1 "cut-off," 3 " fill," 1 engineer. The product is about 30,000 fire
brick or 35,000 common brick per day.
The slip clays used come from Albany, N. Y., and from Seneca
Falls, N. Y. The Albany clay is of course often used alone, but the
Seneca Falls slip is very hard to fuse, and in consequence Albany
slip is usually added to it, the proportions of the mixture being one-
third Seneca Falls, two-thirds Albany. The Seneca Falls slip costs
somewhat more than the Albany clay. It is not so easy to dissolve as
the Albany slip clay, but when dissolved covers the ware more evenly.
When used alone it gives a beautiful bright olive glaze. Used in
combination with Albany slip, it brightens the coloration of the latter
and also gives a somewhat greenish tint.
The Robins & Henderson clay pits are located about 2% miles
southwest of Pinson. A considerable area of clay has been uncov-
ered at this point, but the actual pits are not very large. The exca-
vations show about 20 feet of light-yellow sand, underlain by 15 feet
or more of white clay.
Three miles southwest of Pinson are the clay pits of Mr. R. M.
Davis. The section could not be made out clearly, as the sides of
the pits have been washed in and gullies cut by the rain. About 20
feet of white clay is shown, overlain by reddish sands, these latter
containing little streaks of white sand.
The pits belonging to Mr. Henry Weiss are located about 200 yards
from Davis's pits. The freshly exposed area is very small, as the
overlying material has been washed down by the rain, and the section
is therefore doubtful. Some clay from these pits has been shipped
to the pottery at Memphis, and occasional shipments have been made
to the Chattanooga potteries.
About 3| miles southwest of Pinson are the pits of Mr. C. M. Mor-
row. These showed the most solid clay seen in the Pinson district.
At the top of the pits are 2 feet or so of reddish-yellow weathered
clay, overlying a very dark grayish-black clay, without grit or sand.
Clay from these pits is now used in the pottery at Jackson, Tenn., as
noted later.
As can be seen, the clay pits are all located southwest of Pinson,
and from 2 to 4 miles distant from the station. On the way to the
clay pits, sections were seen containing members not met with pre-
viously. They almost certainly belong to a series low^r in horizon
than the stoneware clays, but the exact relations were not determin-
able, as they were not seen anywhere in contact with the pottery
clays, and no good maps or levels were available. The sections in
question showed 6 feet of yellow, micaceous, slightly indurated
sands, underlain by 5 feet of greenish-black sands, also micaceous and
somewhat indurated. These latter pass downward into harder mate-
388 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
rial, which is often trimmed with an ax or saw, and used as building
stone. It is said to be a durable material, hardening on exposure.
The clay shown at several of the pits wTas too dark in color, and too
free from sand or grit, to resemble closely the typical stoneware
clays. It seems probable that Morrow's pits at least are in the ball
clays of the Lignitic (Tertiary).
JACKSON, MADISON COUNTY, TENN.
The plant of the Jackson Pottery Company is located near the
intersection of the Mobile and Ohio and Nashville, Chattanooga and
St. Louis railroads. Only stoneware is manufactured. The clay is.
ground in one mill, worked by two horses, the amount ground per
day being H to 2 tons. One down-draft kiln is used, fired with Ken-
tucky coal, and holding 5,000 gallons of ware. The clay used is a
mixture, in equal parts, of clay from pits near Jackson and of that
from Morrow's pits near Pinson. The slip used is from Albany,
N. Y., and from East St. Louis, the latter being a "flint" and "spar"
mixture.
The clay pits near Jackson, from which the Jackson Pottery Com-
pany procures its material, are located about 1 mile from Jackson
along the road to Claybrook post-office. The section shown in these
pits is as follows:
Red sands (Lafayette formation) ?
White sands 0 to 10 feet.
Yellow, red, gray, and whitish sands in irregular streaks. 4 to 5 feet.
Clay - 5 feet.
White sand 1 foot.
Clay 8 inches.
White sand for at least 1 foot; no deeper exploration.
The 5-foot bed of clay is separated into layers 4 to 6 inches thick
by thin partings of sand, which is cleaned off before loading. The
contact here between the upper white sand and the red Lafayette
appears to be conformable and very regular. These clays are poorer
than those from Pinson, and can not be used without mixing with
the latter.
HOLLOW ROCK, CARROLL COUNTY, TENN.
Clays from the vicinity of Hollow Rock are shipped to Nashville,
Tenn. These pits, however, could not be reached during the field
work.
HICO, CARROLL COUNTY, TENN.
Clay is now being dug from pits located about 3 miles southeast of
McKenzie, and shipped from Hico station to potteries at Akron,
Ohio; East Liverpool, Ohio, and Louisville, Ky.
ECkkl.] CLAYS OF TENNESSEE AND MISSISSIPPI. 389
M'KENZIE, CARROLL COUNTY, TENN.
A pottery located in this town is now shut down. The clay used
when it was in operation was obtained from pits east of McKenzie.
HENRY, HENRY COUNTY, TENN.
A plant is now in process of erection at Henry. It is said that
local clay will be used, and that the principal product will be fire
brick.
PARIS, HENRY COUNTY, TENN.
J. T. Currier operates two potteries near Paris. The principal
plant is located about H miles east of Paris station. A two-horse
pug mill is used for grinding the clay and is capable of tempering
about 11,000 pounds a day. Three turners are employed. Two kilns
are in operation — one, a down draft, 16 feet inside diameter, with a
capacity of 3,000 gallons; the second a patent (Howard) kiln, with a
capacity of 2,000 gallons of ware. (Seven pounds of clay are equiva-
lent to 1 gallon of stoneware.) The down-draft kiln is fired with
coal, taking 120 bushels; the Howard kiln uses wood, 5 cords being
required. The slips used are Albany and a "flint" and "spar"
mixture.
The second pottery is located about half a mile east of the other
and emploj^s two turners. One down-draft kiln, having a capacit}^ of
2,000 gallons, is in use.
Currier's pits are located about 1 mile east of the principal pot-
tery. The section shown there is —
Brown loam 2 to 3 feet.
Gravel 1 to 3 inches.
Sandy, yellowish clay 1 to 3 feet.
Grayish clay, not very uniform in color 5 feet.
No deeper excavation.
I. Mandle (St. Louis, Mo.) has pits located about three-quarters
of a mile east of the preceding, on the next road to the south. An
area of about 60 feet b}^ 50 feet has been opened up. The sections
shown are as follows :
Section on east side of Mandle' s i)it: Feet.
Reddish sands .. _. 2
Clay 4
Black clay, lignitic 1
Brown clay (ball clay) 5
Section on west side of Mandle' s pit:
Light-gray clay •_ 15
Black clay. 1
Ball clay 5
As will be seen from the above sections, whose bases are at the
same level and only about 60 feet apart, the top beds are very
irregular. The light-gray clay is shipped to East Liverpool, Ohio,
390 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
being used for saggers, while the ball clay is shipped to the same
potteries, being listed there as Tennessee ball clay No. 3.
It seems probable that Mandle's pits show the contact between the
stoneware clay series and the Lignitic clays, and that the lower beds
in Currier's pits may also belong in the Lignitic series. The geologic
question is in this case of great practical importance, as the Lignitic
clays are mostly as satisfactory for use as ball clays, and are there-
fore of considerably greater value than the stoneware clays.
BRICK CLAYS AND MANUFACTURE.
The brick clays and brick industry of the region were only examined
incidentally, and the brief notes taken at several points are here
inserted, not as being in any sense a complete discussion of the indus-
try, but as calling attention to some of its interesting features.
JACKSON, MADISON COUNTY, TENN.
Four brickyards are in operation in the vicinity of Jackson. All of
them were visited.
Charles Owen's yard is located three-quarters of a mile east of the
court-house, on the Claybrook road. Both common and tire brick
are manufactured — the former being a surficial deposit near the yard
1 foot to 5 feet thick; the latter from stoneware clay, obtained from
pits near those of the Jackson Pottery Company.
The clay goes from the pits to an iron tempering wheel (C. W. Ray-
mond's pattern), which is a vertical wheel revolving in a pit on a hori-
zontal axle, and so arranged that its distance from the center of the
pit is automatically changed gradually and regularly. It is run by
two horses; the pit holds sufficient clay to make 8,000 bricks, which
requires two to two and a half hours' grinding. Three of these wheel
pits are in the yard, only one being in use at present. The bricks are
hand molded on a molding table, as a stiff mud, three bricks to a
mold. Two molding gangs were at work, each consisting of four
men — 1 bringing mud in wheelbarrow, 1 molding, 1 sanding molds,
and 1 putting the bricks on racks. Each gang turns out 6,000
bricks a day. The bricks are dried on pallets in racks and require
about two days to dry thoroughly. Two kilns are in use holding
300,000 and 400,000 bricks. The time required is one month to fill a
kiln, two weeks to burn, two weeks to cool, one month to draw.
W. M. Payne's yard is located near the Union station (Mobile and
Ohio Railroad and Illinois Central Railroad). Clay is obtained near
yard and is about 2 feet in thickness. The bricks are made in an
"Iron Quaker" brick machine (Wellington Machine Company, Well-
ington, Ohio). This machine requires nine persons to operate it — 2
men feed machine from soaking pit, 1 strikes and dumps molds, 1
sands molds, 1 (boy) washes molds, 1 (boy) puis bricks on slats, and
3 carry slats to racks. The output of the machine is 16,000 bricks
kckei,.] CLAYS OF TENNESSEE AND MISSISSIPPI. 391
per day. The bricks are usually dried ou racks ; occasionally on the
ground. One kiln is used, holding 160,000 bricks.
F. A. Williams's yard is located 1 mile west of Jackson. Surficial
clay, nearly 4 feet thick, found near the yard, is used. A little fire
brick is burned, for which stoneware clay is obtained from pits near
those of the Jackson Pottery Company. Four tempering pits are
in the yard; only one is in use at present, and that is equipped with
a Raymond wheel. Each pit holds material for 6,000 bricks, and
requires four hours' grinding. Bricks are hand molded by a mold-
ing gang, consisting of 5 persons, 1 wheeler, 1 molder, 2 "oif-bearer"
(carrying from table to rack), and 1 sand boy. A gang turns out
6,000 bricks per day. Fire brick and tiles are hand molded and
burned like common bricks. Some of the fire brick is pressed. Two
kilns are in use, each holding 270,000 bricks. Product per year,
15,000,000 common bricks; 100,000 fire bricks.
E. R. McCabe's yard is located opposite Jackson Pottery Company's
plant. Surficial clay, 4 to 8 feet thick, is used. The bricks are made in
a soft-mud machine (Jonathan Gregor's Sons Co.). Persons required
for operations are — 4 truckers, 1 mold sander, 1 striker, 1 dumper, 2
temperers, 1 sand boy and mold washer, 4 men at bank digging and
loading, 3 cart boys, and 2 slat boys. The product is 25,000 bricks
per day of eight hours.
HUMBOLDT, GIBSON COUNTY, TENN.
Two brickyards are located here, one of which is not operated at
present. The other was visited.
W. II. McKnight's yard is located 1 mile east of station. Reddish
surface clay, 3 feet thick, is obtained near the yard. Common brick
is the only product. The clay is tempered by a Raymond wheel,
and hand molded. All operations save burning are paid for by the
thousand.
Per thousand.
Melding, 1 man, at $0. 30
Wheeling, 1 man, ~at --- .18
Tempering, 1 man, at .18
Off-bearer, 2 men, at .12
Wheeling to kiln , at _ _ _ _ .20
Setting in kiln, at . 12|
The bricks are dried on racks. The kiln requires one-third cord of
wood per thousand bricks.
FULLER'S EARTH DEPOSITS OF FLORIDA AND GEORGIA.
By T. Wayland Vaughan.
INTRODUCTION.
The first fuller's earth discovered in the United States was at
Quincy, Fla., in 1893. Since 1896 details regarding new occurrences
have annually appeared in the volume on Mineral Resources, pub-
lished by the United States Geological Survey. A discussion of the
Florida and Georgia deposits is given in the present paper.
Extensive deposits of fuller's earth occur in Decatur County, Ga.,
and in Gadsden, Leon, and Alachua counties, Fla. With the excep-
tion of the Alachua County deposits, they are all of Upper Oligocene
age, and equivalent with the Alum Bluff beds.
DECATUR COUNTY, GA.
Lester property near Attapulgus. — The material occurs in the south-
ern and eastern slopes of the hills 1± miles west of Attapulgus, where
Mr. J. D. Lester has sunk ten pits, nine of them being on the south
side of the road from Attapulgus to Faceville, and on the west side
of Sanborn (or Little Attapulgus) Creek, and the remaining one on
the east side of that creek. Martin Mill Creek runs east across the
area in which the nine pits have been dug, and cuts below the level
of the f uller's-earth stratum. Three of the prospects are on the north
side of the creek, and six are on the south side. The first three extend
from the road to the creek. The distance between the outer prospects
is about 700 yards. The distance across the prospects on the south
side of the creek is about 400 yards. Fuller's earth was encountered
in all the prospects. The thickness on the north side of the creek
at the foot of the hill was 2^ feet; on the south side it varies from 3
to 9 feet.
Section in deepest pit on Lester property.
Feet.
5. Soil and red clay - about. . 2
4. Blue clay do 4
3. Grayish sand and fuller's earth . '. . . _do 5
2. Fuller's earth do 9
1. Whitish or bluish sand mixed with fuller's earth and containing a few poor
fossils 1 -f-
392
vattghan.] FULLER S EARTH OF FLORIDA AND GEORGIA.
393
Thirty yards north of this pit, stratum No. 1 of the section given
above was penetrated. It was 4 feet thick, and beneath it was blue
clay mixed with fuller's earth.
Analyses of fuller's earth from mines of Mr. J. D. Lester, Attapulgus, Ga.
[Analyst, H. Ries.]
Constituent.
1.
2.
Silica
Per cent.
55. 90
12.40
2.40
1.00
8.12
10. 50
9.40
Percent.
57 26
Alumina
is 33
Ferric oxide _
1 87
Lime. - .- - .. -
2. 58
Magnesia _
1 06
Water
9.40
Moisture . - .
9 00
99.72
99. 50
Two practical tests gave the following results : "In the first, mineral
oils were bleached very nearly to the standard shade. In the second,
the material showed with cotton-seed oil very fair bleaching qualities,
but still was not quite equal to the English material."
In the well bored at Mr. Lester's house on the hill the fuller's earth
was struck at a depth of 42 feet. It was also found on property
belonging to Mr. G. P. Wood, immediately south of Mr. Lester's.
Connell property , near WTiigham. — A pit sunk 1 mile south of the
house of Mr. R. A. Connell showed 6-J feet of fuller's earth, with 19|
feet of overburden. An auger boring in the creek bed near b}^
showed 1 foot of fuller's earth and 10 feet of overburden. Other pits
sunk on Sears and Wolffs creeks showed several feet of fuller's earth,
with 5 to 8 feet of overburden.
Near WithlaeoocJiee Creek. — A mine on the west side of Withla-
coochee Creek, about one-fourth mile northeast of the Georgia- Florida
State line, was opened by John Howard in 1896 or 1897 and sold to
the Owl Commercial Company in the same }^ear. There was from 4 to
8 feet overburden of soil, clay, and white or brownish sand, and
immediately above the fuller's earth a layer of bluish or reddish sandy
clay; then 2 feet, or a little more, of fuller's earth, underlain by whitish
argillaceous sandstone. The bed is not constant in character. On
the north side of the road there is a sand seam in the fuller's earth.
On the east side of the creek there is an exposure in the roadside
The overburden has been removed from an area of about 50 feet square.
Several carloads of material have been piled up and placed under a
shed.
This fuller's earth has not been analyzed, bul has been practically
tested by Dr. Heinrich Ries. It is of the same quality as that from
394 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bttll, 213.
the land of Mr. J. D. McPhaul, NE. £ sec. 16, T. 3 N,R.4W, Gads-
den Comity, Fla. These two samples, when tested with cotton-seed
oil, were found to bleach it as well as the Sumter material which was
prepared and sent to Charleston. When tested with crude petroleum
it was found not to bleach it quite so well as the original Quincy
material.
Ries states that the Sumter (S. C.) material bleached cotton-seed
oil as well as English earth, and bleached petroleum practically as
well as that from Quincy.
Colin property near Attapulgus. — On Messrs. Colin & Co.'s prop-
erty fuller's earth occurs at a point 2 miles east of Mr. Getzlow's
house. It is overlain by a few inches of soil and 2^ feet of cAay, and
is at least 4 feet thick.
Fuller's earth also occurs on land in the NE. i sec. 8, and E. | sec.
0, T. 3 N., R. 3 W., in Florida. Mr. Mark W. Munroe is interested in
this property and in lots in Georgia.
GADSDEN COUNTY, FLA.
Near River Junction. — Four miles southeast of River Junction is
the mine formerly worked by Mr. Ilymeson.
Section beginning at the f<>i> of the hill on the Ilymeson property.
Feet.
4. Surface sands, beneath which arc reddish sands containing some quartz
gravel . 60
3. Stiff blue clay, the top of the fuller's earth deposit 4
2. Fuller's earth. A considerable amount of the overburden had been thrown
off, but due to weathering and wash there is no really good exposure.
Judging from what can now be seen, according to a roughly leveled sec-
tion, ifc seems that the deposit is at least 8 feet thick, and it may be thicker.
There is no means of determining its horizontal extent. A box of the
earth was collected from the best exposure.
1. Immediately beneath the fuller's earth there appears t< > be ;i deposit of sandy,
very stiff blue clay. Thickness unknown.
Generalized section near River Junction.
Teet.
Surface sands 60
Clay and fuller's earth . 10
Not exposed, but probably argillaceous sands 17
Chattahoochee chalk or limestone with some layers of marl about 88
The rocks beneath the Chattahoochee formation are not exposed near River
Junction.
The inference from this section apparently would be that the Chat-
tahoochee limestone is 88+ feet in thickness, separated by 17 feet of
unexposed strata from the deposit of fuller's earth, which would come
above. This would stratigraphieaHy correlate the deposit of fuller's
earth with the Alum Bluff beds.
Dr. H. Ries analyzed and tested fuller's earth from this property,
with the following results:
vaughan.] FULLER S EARTH OF FLORIDA AND GEORGIA.
395
Analyses of fuller's earth front the Hyyieson mine.
Silica
Alumina . . .
Ferric oxide
Lime
Magnesia . _ .
Water
Moisture . . ,
Per cent.
59. 00
15.05
3.95
.20
3.70
11.40
. 7. 80
Total 100.10
Fuller's earth from the Hymeson mine, 3 miles south of River Junction, the
sample having been taken from the crusher at River Junction, Fla. This exerted
only a moderate bleaching action on the cotton-seed oil, and would not bleach
mineral oils very well.
Mr. William Bruce states that there is fuller's earth halfway
between River Junction and the Hymeson mine, near the top of the
hill, and also near Rockbluff, back from the bluff, in the ravines
among the hills.
Mosquito Creek. — There is an exposure of fuller's earth on the south
bank of Mosquito Creek, near the foot of a bluff, on land belonging
to Mr. John D. McPhaul. The overburden is here too great for
working. The deposit is along a small stream running north into
Mosquito Creek in the NW. £ sec. 16, T. 3 N., R. 4 W.
A section in the pit shows overburden (sand), 4 feet; fuller's earth,
6 feet. The bed was not completely penetrated.
The following is an analysis by Dr. Ileinrich Ries of fuller's earth
from the NE. £ sec. 16, T. 3 N., R. 4 W., Gadsden County, Fla., from
land of Mr. J. D. McPhaul:
Analysis of
fuller
s earth
from
the
McPhaul
1"
operty.
Constituent.
Per cenl .
Percent.
Silica .
58.50
I 1.30
2. 10
1.30
6. 50
1.80
9. 5
7.00
62. 85
Alumina
15. 36
Ferric oxide
2 25
Lime
1.39
Magnesia
6. 98
Alkalies
1.93
Water and C02. .
10. 20
Moisture
101.00
100.06
Dr. Ries remarks: "As the moisture content of this sample was so
large I have in the second column given the analysis with the moist-
ure deducted and the percentages recalculated on the basis of the
remainder being 100 per cent."
The material was also exposed nearby in the bed of a crook. The
slope down to the creek valley is gradual. A strip several hundred
396 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
yards wide and probably half a mile long could be worked. Fuller's
earth occurs also on the land of Mr. A. J. Key, in sec. 15, T. 3 N.,
R. 4 W. ; and on the land of Mr. Elias Howell, in sec. 10, T. 3 N.,
R. 4 W., and extends along the creek about one-half mile below
Mr. McPhaul's.
Dr. Ries states that this earth is very similar to that on Withlacoo-
chee Creek, 8 miles north of Quincy. Both bleached cotton-seed oil
as well as the Sumter, S. C, material, but did not bleach crude
petroleum quite as well as the original Quincy material.
Near Quincy. — The following is a section through the fuller's earth
at the Chesebrough Manufacturing Company's mine, 1 mile south of
Quincy.
Section of Chesebrough Manufacturing Company's mine.
Feet.
5. Overburden of clay and sands 7
4. Fuller's earth (average) 4
3. White argillaceous sandstone containing fossils 5
2. Fuller's earth 0
1 . Soft sandstone, sand, and fuller's earth 15
It is estimated that there are about 10,000 tons to the acre. About
2 acres have been mined, and 20,000 tons were taken out. Mr. T. L.
Ward states that operations began in 1895, and stopped in December,
is;)!), because the Standard Oil Company had sufficient earth on hand.
An examination of the section at the mine of the Owl Commercial
Company where stripping is practiced showed the following section:
Section at mine of the <>ir/ Commercial Company.
Feet.
4. Overburden 5 to 20
3. Fuller's earth ._ 6 to 10
2. Sandstone with crystals and lumps of calcite 3 to 4
1. Fuller's earth 5 to 6
Fuller's earth occurs along Quincy Creek, above the preceding-
mine, on land belonging to Mr. William Bruce, and also on the prop-
erty of Messrs. Taussig & Wedeles. The fuller's earth here seems
to be of good quality and about 8 feet thick; the overburden is 4 to 5
feet, and transportation is near at hand. Analyses and tests by
Dr. Ries follow:
Analysis of fuller's earth from, land of Messrs. Taussig <fe Wedeles.
Per cent.
Silica 60. 70
Alumina 14.10
Ferric oxide 2. 40
Lime 1.65
Magnesia 2.08
Water 9.70
Moisture 9. 30
Total 99.93
Sample from the land of Taussig and Wedeles, sec. 2, T. 2 N. , R. 4 W.
This did not bleach very well.
vaughan] FULLER S EARTH OF FLORIDA AND GEORGIA. 397
Analysis of fuller's earth from land of Mr. William Bruce.
Per cent.
Silica 60. 80
Alumina 15. 45
Ferric oxide 1 . 95
Lime 1. 60
Magnesia 3. 12
Water 9.90
Moisture 6. 90
Alkalies .70
Total . 100.42
Practical tests gave the following results: Its bleaching power on
cotton-seed oil was but moderate. It bleached the petroleum to the
standard shade adopted by the Standard Oil Company.
Near the residence of Mr. Carmen, who lives 4 miles east of Quincy,
outcrops of fuller's earth occur along the creeks and in the hillsides.
Seven miles east of Quincy are other outcrops.
LEON COUNTY, FLA.
Twelve miles west of Tallahassee, on property belonging to Messrs.
W. H. Allen & Sons, fuller's earth occurs. Several pits have been
sunk by Mr. Rosendale. The overburden is about 6 feet, and there
are about 8 feet of fuller's earth. The land lies rather flat, along a
small creek running into the Ochlockonee River.
The following gives the results of two practical tests by Dr. Ries:
(1) Sample of fuller's earth from the land of Mr. W. H. Allen, 12 miles west
of Tallahassee. I was not able to make this bleach mineral oil, or at any rate the
bleaching action was slight, although I tried twice.
(2) Sample of fuller's earth from 12 miles west of Tallahassee, on the land
of Mr. W. H. Allen. This bleached the cotton-seed oil fairly well, but was not
equal to the English material.
A section on the Seaboard Air Line Railwaj^, about 1 mile east of
Tallahassee, at milepost 163, shows the following exposures:
Section on Seaboard Air Line Railway.
3. The upper 25 or 30 feet at the ends of the cut are reddish, yellowish sands.
2. Sands with clay partings, 5 to 10 feet.
1. Whitish or bluish clay resembling fuller's earth, in thin lamina? with sand
partings, 4 to 5 feet.
Another cut, between mileposts 163 and 164, shows a similar sec-
tion, in which the clay at the base resembles fuller's earth even more
closely than that in the section first described.
ALACHUA COUNTY, FLA.
DeviVs Mill Hopper. — This is a lime sink several hundred yards in
diameter and over 100 feet in depth in the Vicksbnrg limestone. It
is situated about 11 miles from Alachua, on the road to Gainesville,
being 5 or 6 miles from the latter place. A thin stratum of fuller's
earth, apparently interbedded with the limestone, was discovered in
the side of this sink.
398
CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
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GEOLOGICAL SURVEY PUBLICATIONS ON CLAYS, FULLER'S EARTH, ETC.
In addition to the papers listed below, references to clays will be
found in the publications listed under the head of " Cements," on
page 381. A bulletin will soon be issued by the United States Geo-
logical Survey, dealing with the clay deposits and industries of the
entire eastern United States.
Branner, J. C. Bibliography of clays and the ceramic arts. Bulletin No. 143,
114 pp. 1896.
Golding, W. Flint and feldspar. In Seventeenth Ann. Rept., Pt. Ill, pp. 838-1
841. 1896.
Hill, R. T. Clay materials of the United States. In Mineral Resources U. S.
for 1891. pp. 474-528.
. Clay materials of the United States. In Mineral Resources U. S. for
1892, pp. 712-738. 1893.
Ries, H. Technology of the clay industry. In Sixteenth Ann. Rept., Pt. IV,
pp. 523-575. 1895.
. The pottery industry of the United States. In Seventeenth Ann. Rep.,
Pt. III., pp. 842-880. 1896.
Shaler, N. S.. Woodworth, J. B.. and Marbut, C. F. The glacial brick clays
of Rhode Island and southeastern Massachusetts. In Seventeenth Ann. Rept., Pt.
I, pp. 957-1004. 1896.
Wilber, F. A. Clays of the United States. In Mineral Resources U. S. for
1882, pp. 465^-475. 1883.
. Clays of the United States. In Mineral Resources U. S. for 1883-1884,
pp. 676-711. 1885.
400
GYPSUM, SALT, BORAX, AND SODA.
The mineral products grouped under the above heading, though
applied to widely different uses, form a somewhat natural group so
far as origin is concerned. Their close connection becomes obvious
when their study in the field is attempted, for it is commonly the case
that two or more of these salts will be found in adjacent and closely
related deposits. This is due to the mode of origin of such deposits.
The materials here grouped include certain sulphates, chlorides, car-
bonates, or borates of lime, magnesium, sodium, or potassium; and
deposits of commercial value are due in almost every case to the
deposition of these salts, by evaporation, from the sea or lake water
in which they were contained in solution.
The most important, and fortunately the most widely diffused, of
these materials is common salt, whose uses, both in the preparation
and preservation of food and in the chemical industries, are rapidly
increasing. For a report on field work by the Survey, during 1902, on
the Virginia salt and gypsum deposits see pages 406-416. Appended
to this report are tables of analyses of rock salts, brines, and commer-
cial salts from various United States and foreign localities.
The next in importance of these materials is gypsum. In addition to
the report on Virginia gypsum, noted above and presented in this bul-
letin, all the commercially important gypsum deposits of the United
States will be described .in a bulletin of the United States Geological
Survey, now in preparation.
A report on the California borax deposits has recently been issued
by the Survey. This, together with other Survey publications on the
materials of this group, will be found listed on page 417. The parts
of that paper dealing with the worked deposits are here presented
under the title of .Borax^deposits of Eastern California.
BORAX DEPOSITS OF EASTERN CALIFORNIA.
By M. R. Campbell.
INTRODUCTION.
The occurrence of deposits of borax in the United States, so far as
known, is limited to the States of California, Nevada, and Oregon.
The industry has passed through several stages of development since
its inception in this country. Originally borax was obtained by evap-
Bull. 213—03 26 401
402 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
orating the waters of Clear Lake, about 80 miles north of San Fran-
cisco, where it was first produced on a commercial scale in 1864.
Subsequently the lake water was enriched by the addition of crystal-
line biborate of soda, which was collected from the alkaline marsh
surrounding the lake. The industry flourished at this and other
lakes in California until, in the early seventies, borax in large quan-
tity and in a very pure condition was discovered on many of the alka-
line marshes of western Nevada and eastern California. Refining
plants were established in the vicinity of Columbus, Nev., and at
several points in California, the most important of the latter being in
San Bernardino County, at Searles's marsh, west of the Slate Range;
in Inyo County, near Resting Spring; and at the mouth of Furnace
Creek in Death Valley. These plants flourished for a time, even
though the finished product in many cases had to be transported by
teams to the railroad, 100 miles distant; but the increased production
of borax in this country, together with the importation of large
amounts from Italy, so reduced the price that in a few years most
of the plants were abandoned.
About 1800 it was found that the borax crust on most of the marshes
is a secondary deposit, being derived from the leaching of beds of
borate of lime in the Tertiary lake sediments that abound in the
region. This discovery revolutionized the borax industry, for the
bedded deposits are much more extensive, are more easily accessible,
and are in a purer condition than the marsh crusts. The marshes
were abandoned and a mine was established on a bedded deposit at
Borate, 12 miles northeast of Daggett, San Bernardino County, Cal.
At the present time this plant, owned by the Pacific Coast Borax
Company, is the chief producer of borax and boracic acid in this
country. The value of this deposit led to extensive prospecting in
various parts of the region and to the discovery, in Death Valley, of
enormous deposits that far excel those now being worked near Daggett.
The borax of Death Valley, as well as that near Daggett, occurs in
a regular stratum, interbedded with the semiindu rated sands and
clays that make up the bulk of the strata. These beds are generally
regarded as of Tertiary age, and they are supposed to have been
deposited in inclosed bodies of water.
Since the bedded deposits of borax always occur in association with
strata of this character, it is probable that careful study and search
will reveal deposits of this nature in localities other than Death Val-
ley and Daggett.
For the purpose of locating outcrops of lake beds, and studying
their relations and contents, the writer made a rapid reconnaissance
across southern California in the spring of 1900. The trip was too
hastily made to permit of detailed examinations, or of observations
much beyond the line of travel, but many facts were found which
Campbell] BORAX DEPOSITS OF EASTERN CALIFORNIA. 403
have a bearing upon the occurrence of borax and its distribution, and
these are embodied in the following paper. Of necessity the writer
does not enter into a systematic treatise of the subject, but presents,
in the form of an itinerary, the data gathered during his trip.
BORATE.
The principal deposit of boron salts occurs at Borate, about 12 miles
north of Daggett, in the vicinity of the old Calico mining district.
The mineral found here is borate of lime, or colemanite, and it occurs
as a bedded deposit from 5 to 30 feet in thickness, interstratified in
lake sediments. These lake beds are composed of semiindurated
clays, sandstones, and coarse conglomerates, with intercalated sheets
of volcanic tuff and lava. The rocks are intensely folded, the axes of
the folds lying in an east- west direction. The lake beds extend in the
same direction across the mountains for a distance of about 8 miles.
It has been supposed that these deposits probably continue westward
under the Pleistocene drift of the desert, but there is no evidence at
hand to prove such an assertion. In fact, the lake beds at Borate do
not come down to the foothills of the mountain ; they are cut off and
infolded with the crystalline rocks of the Calico district. Lake beds
are present west of Calico Valley, and a bed of colemanite has been
struck in a shaft in this locality at a depth of 200 feet. Although the
colemanite is interbedded with sand and clay, it is not coextensive
with these strata. As a traceable bed it probably extends for a dis-
tance of a mile and a half; beyond this limit it is very thin, and in
many places it is wanting in the section. At the Borate mine there
are two outcrops of colemanite, either on parallel beds or on one bed
that has been so closely folded as to give two parallel layers about 50
feet apart. The beds strike approximately east and west, and dip to
the south from 10° to 45°. A railroad connects the mine with the
mill which is located on the west side of the mountain, and also with
the Santa Fe Railway at Daggett.
DEATH VALLEY.
The range of mountains on the east side of Death and Mesquite
valleys is separated into two parts by a low gap formed on lake beds.
The mass tying north of these sediments is known as Grapevine
Mountain, and that to the south, including the lake beds, is called
Funeral Mountain.
The lake sediments of this region are composed of clay, sand, and
gravel, with many beds of volcanic tuff and intrusive lava sheets
toward the base of the series. Coarse gravel abounds near the con-
tact between these beds and the Paleozoic rocks of Grapevine Moun-
tain, showing that at the time of deposition this was a shore or bound-
ary wall of the valley in which the lake was located. The strike of
404 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
the beds is parallel with the northeastern margin, and the dip is 20°
to 45° toward the northeast. The beds maintain this attitude on both
sides of the range, and they do not dip under the valleys on either
side, as they have been supposed to do.
Interbedded with the rocks of this series is a bed of colemanite
(borate of lime), which, though probably not continuous, shows in
outcrop in a number of places across the mountain, a distance of at
least 25 miles. This constitutes the largest deposit known in this
country and presumably the largest in the world. The bed has been
opened low in the foothills on the east side of the mountain 4 or 5
miles south of the Ash Meadows road. At this point the bed is
visible for several hundred yards, and in the prospect pits it has a
thickness of from 4 to 10 feet. It is said to exceed these figures, but
no thicker sections were seen. The bed is composed of a mass of
crystalline colemanite which mines readity and with little waste.
In the western foothills of Funeral Mountain a bed of this mineral
is exposed in the ravines for a distance of a quarter of a mile, and
along this outcrop it varies in thickness from a few inches to 20 feet.
At no point is it a solid, regular bed, but it consists of irregular masses
and stringers of colemanite embedded in clay. The crystals are small,
seldom exceeding a quarter of an inch in diameter, and the large
masses are nearly pure. According to Superintendent Roach, of the
Pacific Coast Borax Company, the largest mineral deposit occurs
about 9 miles up Furnace Creek, on a nearly direct line between the
outcrops just described At this point he reports a bed of boracite
60 feet in thickness. Phis was not seen by the writer, but there are
strong indications of the presence of minerals of this character, and
it is probable that large deposits occur in this locality.
Borax was once manufactured 2 or 3 miles north of the point where
Furnace Creek emerges from the hills into Death Valley. The plant
was situated on the margin of the alkaline marsh, and the crude
material was derived from a certain part of the marsh where coleman-
ite accumulated. It is now known that the mineral is derived by
solution from the bedded deposit described above, and that its accu-
mulation on a certain part of the marsh is due to the solution being
carried to that place by a small stream.
Death Valley contains an immense salt field, which may in time
become valuable. It extends south from above the old borax works
at least 30 miles. At the place where it is crossed by the road from
Furnace Creek to Bennett Wells it is nearly 3 miles wide, and it prob-
ably varies from 2 to 4 miles in different parts of the basin. The salt
is not white, like the marsh at Salton, in Colorado Desert, but it is
brown with dust and sand that is constantly being blown upon it.
The salt stands in pinnacles 2 to 3 feet in height, making a surface
so rough that it is impassable for a horse until the projections are
pounded down with a sledge. With the implements at hand the
campbkll.] BORAX DEPOSITS OF EASTERN CALIFORNIA. 405
thickness of the crust could not be determined, but it can not be less
than 1 foot of solid salt. A sample collected in the middle of the
field on this road shows that the salt is composed of chloride of sodium,
94.54 per cent; chloride of potassium, 0.31 per cent; sulphate of
sodium, 3.53 per cent; sulphate of calcium (hydrous), 0.79 per cent;
moisture, 0.14 per cent; undissolved residue (gypsum and clay), 0.50
per cent; total, 99.81 per cent. The presence of the large amount of
mechanical impurities as well as the large percentage of sulphate of
soda would render refining necessary before the salt could be placed
upon the market, a process that would be very expensive under
present conditions of great scarcity of fuel and water and lack of
railroad transportation.
SALT AND GYPSUM DEPOSITS OF SOUTHWESTERN VIRGINIA.
By Edwin C. Eckel
INTRODUCTION.
The field work on which is based the following report on the Vir-
ginia salt and gypsum deposits was carried on by the writer during
August, 1902, under the direction of Dr. C. W. Hayes. The writer's
thanks are due to the gypsum producers of the region, who cordially
cooperated with him in his investigations.
Though salt and gypsum are found elsewhere in Virginia, the only
economically important deposits of these minerals occur in the south-
western portion of the State. These deposits are located along the
valley of the North Fork of Holston River, and have been developed
quite extensively in Smyth and Washington counties.
The occurrence of salt brines in the Holston Valley was known at
least as early as 1781, as Jefferson mentioned the fact in his Notes
on Virginia. Rock salt was not, however, discovered until 1840.
Gypsum or "plaster" seems to have been recognized early in the
nineteenth century, though the writer has not been able to ascertain
the exact date of its discovery.
Though the salt and gypsum deposits have been long known and
worked, and have been examined by many geologists, a wide range
of opinion exists as to their age and origin, as will be seen on com-
paring the literature of the subject. It is sufficient in this place to
note that, as to age, the deposits have been variously referred to the
Silurian, Carboniferous, Triassic, Tertiary, and Pleistocene, while
different authorities have considered them as originating from deposi-
tion from sea water, from deposition from lakes, by the decomposition
of pyrite and resulting action on fragments of limestone, or by the
action of sulphur springs on unweathered limestone.
The work of the last field season would seem to prove that both the
salt and gypsum deposits originated from deposition, through the
evaporation of sea water in a partly or entirely inclosed basin, and
that they are of Lower Carboniferous age, being immediately overlain
by the massive beds of the Greenbrier limestone and underlain by
Lower Carboniferous sandstones..
406
eckel.] SALT AND GYPSUM OF SOUTHWESTERN VIRGINIA. 407
STRATIGRAPHY AND STRUCTURE.
The areal geology and structure of the district have been carefully
worked out by Professor Stevenson, and are described by him in the
paper cited below. a
In the forthcoming bulletin on the gypsum deposits of the United
States, to be published soon by this Survey, will be found a geologic
map of the Virginia salt and gypsum region, with structure sections,
modified very slightly from that published by Professor Stevenson.
A summary of the more important geologic features will here be given.
The ridges (Brushy Mountain, Pine Mountain, Little Brushy Moun-
tain, etc.) which border the valley of the North Fork of Holston on
the northwest are made up of Upper Silurian, Devonian, and Lower
Carboniferous rocks, dipping southeastward (or riverward) at angles
of 20° to 40°, and striking approximately parallel with the course of
the river. The southeastern slope of these ridges is generally formed
by the shales and shaly sandstones of the Lower Carboniferous which
underlie the Greenbrier limestone. The Greenbrier limestone itself
occupies the interval between the foot of the ridges and the river, and
extends, on the southeastern side of the river, to the great fault
described as the Saltville fault by Stevenson, and farther south as the
Rome fault by Hayes. This fault brings up Cambro-Silurian lime-
stones on its southeastern side. The location of the fault in the salt
and gypsum district may be described as follows : Beginning at the
southwestern end of the area, the fault crosses the Saltville branch rail-
road at a point several hundred yards south of the plaster mill of the
Buena Vista Plaster Company, runs a little above the foot of the ridges
on the southeast side of the salt wells, and in a direction approximately
north, 60° east, crossing the river near Broad Ford, and passing north
of the settlement at Chatham Hill. The rocks on the southeastern
side of this fault are limestones and shales of Cambrian and Lower
Silurian age, dipping southeastward, and ma}' be disregarded in a
further discussion of the salt and gypsum deposits. Trilobite remains
occur in these Cambro-Silurian limestones in a railroad cut south of
the Buena Vista mill.
SALT AND GYPSUM DEPOSITS.
In describing the geologic and areal relations of the salt and gyp-
sum deposits, the area southeast of the Saltville fault may, as above
noted, be dismissed from consideration. The deposits are confined to
a belt north of this fault, and extending from the fault line to the
line of outcrop of the Lower Carboniferous standstones, which passes
along the foot of Pine Mountain and Little Brushy Mountain. This
intervening space is occupied by the massive limestones and slial}7
n Stevenson, J. J., Notes on the geological structure of Tazewell, Russell, Wise, Smyth, and
Washington counties of Virginia: Proc. Am. Philos. Soc, Vol. XXII, pp. 1 14— lt>l .
408 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
limestones, with salt and gypsum beds, here included in the "Green-
brier limestone."
The Greenbrier limestone, as that term is here applied, consists of
the following members, from the top down :
Feet.
1. Blue limestone, usually heavy bedded, with some beds of cherty
limestone, and with occasional beds of grayish, black, or green-
ish fossiliferous shales near its base 1, 000+
2. Shaly limestones, with one or more beds of gypsum, followed
below by blue shales or slates, which in turn are underlain by
shales or shaly limestones carrying thick beds of rock salt 600 to 1, 000
Of the two members the lowermost (2) alone requires attention here.
While the uppermost member of the Greenbrier limestone appears to
have a wide distribution, the lower, carrying the salt and gypsum,
seems to be developed only locally, as it has not been recorded except
in the region here described. As the salt and gypsum beds are too
soluble to be well exposed at the surface, and the interbedded shaly
limestones and shales weather rapidly, it is impossible to find a good
natural section of this important group of beds. Well sections would
be of great service, but unfortunately no well has passed completely
through the series. By utilizing the records of various wells and bor-
ings, however, some idea of the strati graphy may be obtained.
At various dates between 1815 and 1857 a number of wells were
bored on the Robertson property, with the objects of ascertaining the
thicknesses of the various gypsum beds, and also of determining
whether or not brine or rock salt could be obtained on the property.
Through the courtesy of Col. Wr. B. Robertson, of the Buena Vista
Plaster and Mining Company, the writer is enabled to present the
records of most of these wells.
The wells started in the gypsum-bearing section of the Greenbrier
limestone about 200 feet below the massive blue limestones. Several
of them penetrated through the gypsiferous beds, apparently stopping
near the top of the salt beds.
Records of wells on Robertson property.
Well A, bored between 1815 and 1820: Feet.
Red clay 0-14
Clay and plaster 14-120
Pure plaster « 120-160
WellB, bored in 1847:
Red clay 0-10
Clay and plaster, buhrstones 10-30
Clay and plaster (deep red) 30-50
Pure plaster 50-95
Impure blue plaster . 95-163
Hard blue slate . 163-420
"Pure plaster is said to have extended 40 feet deeperthan is above shown— i. e., from 160 to 200
feet in depth.
ECKEL] SALT AND GYPSUM OF SOUTHWESTERN VIRGINIA. 409
Well C, bored in 1847:
Red clay 0-10
Clay and plaster, with brown rocks 10-70
Pure plaster 70-100
Slate and plaster . 100-200
Hard bine slate - 200-360
Red slate 360-480
Gray slate 480-495
Red rocks, a little salty 495-505
Well D, bored in 1847:
Red clay 0-10
Clay and plaster 10-62
Plaster, with a little clay 62-200
Red clay, with a little plaster .... . _ . 200-385
Red clay, alkali, and salt 1 385-387
Pure plaster 387-590
Well E, bored in 1847:
Red clay 0-10
Clay and plaster 10-16
Impure plaster 16-50
Pure plaster . 50-102
Slate and plaster -_ 102-165
Nearly all plaster ....._ 165-210
Blue slate 210-320
Blue slate and plaster _ 320-390
Yellow soapstone 390-445
Pure plaster . '. 445-490
Red rock, with a little salt 490-505
Well F. bored in 1853:
Clay 0-17
Clay and plaster 17-50
Pure plaster 50-83
Hard black flint rock 83-90
Pure plaster ... 90-96
Plaster and sulphur balls 96-105
[Recordlost] -. 105-109
Red and yellow soapstone 109-120
Hard blue slate and red, blue, and gray rock 120-359
Yellow and blue slate ._ . _ 359-390
Yellow and blue slate, salty 390-460
Well G. bored in 1854:
Sand and gravel 0-20
Blue clay 20-30
Hard white sand rock 30-40
Clay and plaster •_ 40-55
Buhrstone . 55-60
Another well was bored in 1845. No record was kept and it is only
known that salt water was struck.
It will be seen that none of these wells gave any appreciable
amount of salt. This may be due to the fact that the salt beds do
not occur at this point or to the fact that the wells stopped some
410 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 218.
distance above the salt horizon. In the writer's opinion the latter
supposition is the more probable. Unfortunately it was impossible to
obtain records of the strata passed through in drilling the salt wells.
It is known, however, that these wells start near the base of the
gypsum-bearing beds and strike rock salt at a depth of about 200
feet. The aggregate thickness of rock-salt beds passed through is
said to be about 175 feet.
By combining all these data, some idea of the thickness of the
lower (gypsum and salt-bearing) member of the Greenbrier limestone
may be formed.
Section of low or member of Greenbrier limestone.
Feet.
Top of gypsiferous series to top of Buena Vista wells 100
Gypsum-bear mg rocks and shales in deepest well 600
Bottom of deepest Buena Vista well to top of salt beds, probably not over .. _ 100
Salt beds and inclosing rocks 175
Bottom of salt beds to Lower Carboniferous sandstones ?
The thickness of the series in the Saltville-Plasterco basin must
therefore be in the neighborhood of 1,000 feet.
MINING AND TECHNOLOGY.
THE GYPSUM INDUSTRY.
The gypsum deposits in this area have been developed at a number
of points along the trend of the belt. These developments will bo
described briefly in order from northeast to southwest.
The most northeasterly point at which gypsum has been found in
the Holston Valley area is on the Buchanan property, located about
3 miles Avest of Chatham Hill post-office. Several small openings can
be seen here, one of which was being worked at the time of visit.
This quarry was about 30 feel deep and 50 feel in length, exposing
gypsum of very good grade. The product is crushed for use as land
plaster in a mill located near the quarry. Extensive exposures of
gypsum occur in the vicinity, but the difficulty of marketing the
product has prevented the development of these deposits, only about
300 tons per year being quarried.
About 3 miles east of Broadford post-office, and some distance north
of the river, gypsum is worked on the property of Mr. John D. Barnes.
The inclosing shaly limestone beds here strike N. 80° E. and dip 40°
SE. Black powder and hand drills are used in extracting the gyp-
sum. The workings, at first in open cut, are now mostly under-
ground, a slope having been run down on the dip of the beds, with
pillars of gypsum left at intervals to support the roof. The product,
which may amount to 500 tons a year, is carried by wagon to a land-
plaster mill located at Broadford, on Laurel Creek.
eokel] SALT AND GYPSUM OF SOUTHWESTEEN VIRGINIA.
411
An analysis, by Prof. M. B. Hardin, of the gypsum rock from the
Barnes property is as follows :
Analysis of gypsum rock from Barnes property , east of Bradford, Va.
Calcium sulphate 78. 60
Water 20.79
Calcium carbonate 0. 21
Calcium chloride Trace.
Magnesium chloride Trace.
Organic 0.12
Silica, alumina, etc 0. 23
At several points between the Barnes property and Saltville gypsum
deposits have been opened, but none have been worked recently.
At Saltville several large openings can be seen. One of these was
worked during 1901 and the early part of 1902, part of the product
being sold for use as land plaster, but most of it being sent to Glade
Spring, at which point it was utilized in the manufacture of Keene's
cement. This industry not proving as successful as had been antici-
pated, the plant was dismantled during 1902. The product, though
fairly satisfactory, was not equal to the imported material or to the
Kansas product.
The writer has recently a described this interesting gypsum product
in some detail, and the following quotation may be of interest here :
Keene's cement is sharply distinguished from the other members of the group
of hydrate cements (or " plasters ".), not only by the properties of the product,
but by its method of manufacture. In its preparation a very pure gypsum is cal-
cined at a red heat, the resulting dehydrated lime sulphate is immersed in a bath
of alum solution, and, after drying, is again burned at a high temperature. After
this second burning the product is finely ground, and is then ready for the market.
This sketch of the process is a general outline of the methods used, and in the
essentials is followed in all plants, though slightly modified at different plants
according to the experience gained by each manufacturer.
The gypsum used should be as pure as possible, and especially it should be free
from such impurities as might tend to discolor the product, which should be a pure
white. Nova Scotia gypsum has been tried and, for some reason, found to be
unsatisfactory. Even the Virginia gypsum, which on analysis shows but a trace of
iron oxide, is not entirely satisfactory, for on heating to the temperature necessary
for the manufacture of Keene's cement, minute red streaks appear in the lumps
of gypsum. The following analyses show the composition of gypsum from Vir-
ginia and Kansas, both of which have been used in a domestic Keene's cement:
Composition of gypsum used in manufacture of Keene's cement.
Kansas.
Vh
ginia.
Lime sulphate . .
77. 46
20.46
.10
.19
.34
1.43
}
Water __.__
99. 58
Iron and aluminum oxides _ _ . -
.036
Silica and insoluble . _ .
Magnesium carbonate
.116
.221
Lime carbonate
"Plasters and. hard-finishing cements in the United States: Engineering News, Vol. XLIX,
pp. 107-108, Jan. 29, 1903.
412
CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
It will be seen that both materials are very pure gypsum, and that there is no
apparent reason why the Virginia material should not be as satisfactory as that
from Kansas.
The calcination of the product is usually carried on in small vertical kilns closely
resembling those which are in common use for lime burning. These kilns are
charged with alternating layers of fuel (usually coal) and lump gypsum. Small
rotary kilns have been used experimentally, but have not proved successful, as the
calcined product from a rotary kiln is discharged in small fragments, which can
not be treated satisfactorily in the alum bath. After burning to a red heat, the
gypsum is submitted to the action of a 10 per cent alum solution. It is then recal-
cined, and finally ground in emery mills.
The product is a very fine-grained white powder. On the addition of water
this cement hardens, but the hardening is slow, relative to that of other plasters.
Another peculiarity of the material is that, even after the hardening has com-
menced, the partly set cement may be reworked with water and will take its set
just as satisfactorily as if the process (of hardening) had not been interrupted.
By far the largest openings of the district are those at Plasterco
post-office (Gypsum station), a mile or so southeast of Saltville. The
gypsum mines at this point are worked by the Buena Vista Plaster
and Mining Company. The bed now worked is about 30 feet thick,
dipping northwestward at an angle of 50 degrees or more, and has
been mined to a depth of 280 feet. The shaft at present used is 180
feet deep. Part of the product is ground for land plaster at the mill
of the company, located a short distance from the shaft, and part is
calcined at the same plant, the total product being about 11,000 tons
per year. The crude gypsum is reduced to 5 inches in a nipper, and
then to about J inch in a rotar}^ crusher, receiving its final reduction
in a Sturtevant rock-emery mill. The material used for land plaster
is then sent to the bagging machines, while that to be calcined goes
to the kettles. A certain amount of wall plaster is also made at this
plant, by the addition of retarder and hair to the calcined plaster.
Analyses of crude gypsum from the mines of this company follow:
Ancrt uses of gypsum from Plasterco post-office, Va.
Constituent.
Lime
Sulphuric acid
Water
Magnesia
Baryta
Alumina and iron
Silica
33. 20
46.04
19.40
.70
.10
2.
33. 20
44.74
20.85
.05
.19
.46
.49
33. 00
47.14
19.07
Trace.
Trace.
0. 55
.02
31.82
40.24
21.30
1.75
1.10
1.95
1.68
1. Crude rock, as mined. P. de P. Ricketts, analyst.
2. Crude rock, as mined. Henry Froehling, analyst.
3. Ground rock, for land plaster. P. de P. Ricketts, analyst.
4. Ground rock, for land plaster. Henry Froehling, analyst.
THE SALT INDUSTRY.
Although indications of salt appear at several points in the region,
the salt industry is at present confined to the immediate vicinity of
j eckel.] SALT AND GYPSUM OF SOUTHWESTERN VIRGINIA. 413
I Saltville. The salt licks of this locality were known, as noted above,
before 1800. Early in the nineteenth century a marsh which covered
! the present site of the village of Saltville was drained by a channel lead-
ing to the Holston, and wells were sunk in the area uncovered. Brine
was pumped from these wells for many years before the presence of
rock-salt beds was established, and the entire salt product of the dis-
trict is still obtained from wells, no mining of the rock salt having
been attempted.
The earliest wells were about 200 feet deep, passing through earth,
clay, gypsum, and shales. In 1842, when the deposits were described
by Hayden, six salt wells had been put down, only two of which
were then in operation. A shaft sunk in 1840 passed through the
usual thickness (18 to 20 feet) of muck, clay, etc., and then through
alternating beds of red and blue shales and gypsum, one of the gyp-
sum beds being 40 feet thick, finally striking a bed of rock salt at a
depth of 220 feet. This salt bed continued to the bottom of the shaft,
at a depth of 273 feet, and was ascertained by boring to extend to 113
feet below the bottom of the shaft. No water was encountered in the
well. This was the first discovery of a bed of rock salt in eastern
United States, though Parker some years before had noticed the
occurrence of salt beds in the Northwest, on the Oregon trail. The
rock salt from the shaft contained, in places, some interbedded shales,
these impurities being commonest near the top of the salt beds. An
analysis of the rock salt gave —
Per cent.
Sodium chloride 99. 084
Calcium chloride Trace.
Calcium sulphate *_ . . . 0. 446
Iron, alumina, etc . 470
A well bored in 1842 to a depth of 214 feet struck a flow of strong
brine at 193 feet. In 1,000 grains this brine contained —
Grains.
Sodium chloride 240. 52
Calcium chloride .08
Calcium sulphate 5. 35
Iron, alumina, etc Trace.
At this date (1842) two establishments were producing salt, the
total annual product being about 200,000 bushels. Analyses gave —
Analyses of salt from Saltville, Va.
,
l.
2.
Sodium chloride - .
Per cent.
98.54
.016
1.444
Per cent.
98. 146
Calcium chloride - -
.034
Calcium sulphate - -
1.820
Further analyses of Saltville brines, rock salt, and commercial salts
will be found in the tables on pages 415 and 416.
414 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
In 1885 Radcliffe discussed0 the Saltville product as follows:
A specimen of the rock salt sent by the superintendent of the salt works was
brownish-red in color, with a crystalline structure, and was obtained while deep-
ening one of the salt wells. This rock salt is not mined, the brine alone being
used for the manufacture of salt. The capacity of the works is at present 450,000
bushels per year, though at one time during the late war the yield was as high as
10,000 bushels per day. According to analysis the rock salt contained—
Per cent.
Sodium chloride 93. 05
Potassium chloride Trace.
Calcium sulphate 2.40
Magnesium sulphate .07
Ferric oxide -• .83
Silica 2.81
Water .30
An analysis of the marketed salt gave 98.89 per cent sodium chloride, with a
small percentage of calcium sulphate, water, and a trace of magnesium sulphate,
showing it to be a high-grade salt.
At present the salt industry in the Ilolston Valley is entirely in the
hands of the Matthieson Alkali Company. I 'art of the product is
marketed as salt, while a Large proportion is utilized in the alkali
plant of the company, located at Saltville.
While it is probable that brines could be obtained by boring in
other parts of the Ilolston Valley, no possible extension of the salt
field could be so favorably located in regard to transportation routes
as is the present producing area near Saltville, with the exception of
the property near Plasterco.
COMPARISON OF AMERICAN AND FOREIGN SALTS.
Analyses of rock salt, brines, and commercial salt, from the Vir-
ginia salt region follow. For comparison, a series of analyses of sim-
ilar materials from other localities, both American and foreign, has
been added.
Most of the salt produced in the United States is obtained b}r pump-
ing and evaporating brines from wells reaching down to beds of rock
salt or to rock formations carrying much saline matter disseminated
through their mass. Part of the remaining product is secured by
mining and crushing rock salt, and part b}r evaporating ocean water
or the waters of salt lakes.
In point of geologic age, the oldest salt-bearing beds now actively
worked in the United States and Canada occur in the Salina group,
near the top of the Upper Silurian. Urines have been obtained, it is
true, from the Medina formation of the Silurian in New York, but
these have never been of much economic importance. The geologic
horizons from which the salt of Ontario and the various States is
obtained are shown below.
"Mineral Resources U. S. for 1883-1884, p. 840.
eokel] SALT AND GYPSUM OF SOUTHWESTERN VIRGINIA.
415
Geologic horizons from ivliich salt is obtained.
Upper Silurian New York." Michigan, Ohio/' Ontario (Canada) .
Carboniferous Pennsylvania, West Virginia, Virginia, Kentucky.
Michigan.
Permian, Triassic Kansas," Oklahoma, Texas.
Cretaceous, Tertiary Louisiana/' Texas.
Recent — sea and lake waters .-Texas, Utah, Nevada, California.
Analyses of rock salts from various localities.
Locality.
Sodium chlo-
ride.
3
V
II
o H
O
•a
.^■72
go
3
t» .
.3 -a
"oS
O
a
a a
tf to
'55 g
.2 a
a*
S3
Authority.
Saltville, Va
99.084
93.05
98. 701
96.885
•98. 28
97.031
99.687
91. 24
99. 53
98.90
98. 731
99.097
Tr.
0.446
2.40
.484
.437
.560
1.4:51
.090
2.81
.214
.838
1.1112
.729
.46
.65
2.05
2. : 5
3.50
0. 07
0.470
3.64
. 743
1.21
.8&5
0.30
Tr.
1.21
.206
1.500
.079
.K39
.080
.030
.039
C. B. Hayden.
Radcliffe.
Do/'.
Retsof,N.Y
0.018
.157
.031
.007
. 032
.57
.109
.146
Tr.
0.055
. 103
. 088
.031
.095
. 05
Tr.
0.022
.013
F.E.Englehardt.
Do.
Do.
Pearl Creek, N.Y
Greigsville, N.Y
Do...
Do.
Do
.158
.017
5. 33
. 007
.014
.034
T.S.Hunt.
Do.
F. E. Englehardt.
P. Collier.
Do
Do
P. W. Taylor.
Cheshire, England _
Do
99.52
98.32
97.70
97.45
96.28
0.01
.02
.02
G.H.Cook.
.15
1.00
.10
.20
.14
G-. H. Cook.
...Do
Do.
Carrickfergus, Ireland..
.08
Do.
Analyses of solid matter of brinet
• from various localities.
Locality.
6
3
a^
0
GO
3
0
Is
O
a
2©
"5:2
£ 0
^3
1°
3
02 .
a-s
a
.2-2
to o3
a p<
£ to
-J
.2 a
a *
3^
£3
£1
Specific grav-
ity of brine.
Authority.
Saltville, Va.
Do.
97. 792
98.139
97. 48
97.60
96.17
95. 866
95.312
95.328
99.01
97.58
81.38
91.95
82.14
82.24
79.45
81.27
98.07
97.92
94.87
0.033
2.17
1.22
1.68
1.68
1.25
2.54
3.03
2.30
.72
2.19
.53
2.39
.46
.30
0.39
Tr.
24.6
26.4
25.65
26. 34
24.52
18.5
16.1
16. 1
26. 15
24.74
22.02
16.61
21.32
24.15
9.2
2.8
26.2
25.1
15.2
1.198
1.192
1.204
1.192
1.142
1.122
1.122
1.205
1. 195
1.179
1.073
1.019
1.20
1.19
1.122
C. B. Hayden.
G.H.Cook.
Pearl Creek, N.Y ..
.26
.51
2.15
.90
.93
1.52
.15
.08
.73
3.19
12.39
12.25
16.48
13.93
.13
.15
0.55
.20
.42
.72
.85
.10
.12
6.91
2.48
5.01
5.22
4.07
4.80
.23
.27
F.E.Englehardt.
Warsaw, N.Y
Leroy,N. Y
Syracuse, N.Y
Do
Do.
Do.
0.004
.008
.002
G.H.Cook.
Do.
Do
Do.
Goderich, Ontario
T.S.Hunt.
Do..
C. A. Goessniann.
East Saginaw, Mich .
Bay City, Mich
.48
Douglass.
C. A. Goessmann.
Saginaw , Mich
Do.
Bay County, Mich . . .
Kanawha, W. Va .
Do.
G. H. Cook.
Pittsburg, Pa .
Do.
Cheshire, England. . _
Do
1.57
1.66
1.83
Do.
Do.
Dieuze, France
3.30
Do.
a Utilize both brine and rock salt, b A specimen evidently much below the average in purity.
416
CONTBIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
Analyses of commercial salts from various localities.
Locality.
6
as
o
6
V .
§S
a
•as
<s u
Saw
a^
pa
o3
O
a
.248
CD 3
fl ft
a p
CO O
SS.S
asQ
5
Authority.
Saltville,Va
Do
Do
Do
98.540
98. 146
98. 45
99. 01
99.18
99.11
98.61
98.89
98.081
97.09
98.072
96.70
97.91
97. 28
97. 031
95.84
95.33
91.31
88.39
0.016
.034
.95
.20
.27
.68
1.02
0.20
.09
.05
.11
.27
1.444
1.820
-----
C. B. Hayden.
Do.
0.40
.70
.50
.10
.10
+
.547
.52
. 753
1 . 79
1.29
1.10
1.50
.65
3.34
1.35
3.31
7
9.70
G. H. Cook.
Do.
Do
Do.
Do
1
Do.
Do
Do.
Do
+
1.087
1.87
. 955
1.43
.67
1.46
1.431
1.043
.32
.70
.36
Tr. -
Radcliffe.
Piffard, N.Y_ — -
Saltvale, N.Y
Warsaw, N.Y
Syracuse, N.Y
Do
. 150
.089
.05
.06
.09
.007
.36
.33
.7(1
1.26
1. is
.055
.118
. 03
.07
.07
.031
.092
.14
.34
.31
.43
.43
0.02
0.081
.013
F. E. Englehardt.
Habirshaw.
F.E. Englehardt.
G.H.Cook.
Do.
Do
Do.
Goderich, Ontario
Do
1
.42
C. A. Goessinann.
Ellis.
Saginaw, Mich
Bay City, Mich
Zilwaukie, Mich
Garrigues.
Hahn.
Kanawha, W. Va
G.H.Cook.
Do.
Do.
GEOLOGICAL SURVEY PUBLICATIONS ON GYPSUM, SALT, BORAX,
AND SODA,
The more important publications of the United States Geological
Survey on the natural lime, sodium, and potassium salts included in
this group are the following:
Campbell, M. R. Reconnaissance of the borax deposits of Death Valley and
Mohave Desert. Bulletin No. 200. 23 pp. 1902.
Chatard, T. M. Salt-making processes in the United States. In Seventh Ann.
Rept., pp. 491-535. 1888.
Day, W. C. Potassium salts. In Mineral Resources U. S. for 1887, pp. 628-
650. 1888.
Sodium salts. In Mineral Resources U. S. for 1887, pp. 651-658. 1888.
Hilgard, E. W. The salines of Louisiana. In Mineral Resources U. S. for
1882, pp. 554-565. 1883.
Orton, E. Gypsum or land plaster in Ohio. In Mineral Resources U. S. for
1887, pp. 596-601. 1888.
Packard, R. L. Natural sodium salts. In Mineral Resources U. S. for 1893,
pp. 728-738. 1894.
Peale, A. C. Natural mineral waters of the United States. In Fourteenth
Ann. Rept.. Pt. II, pp. 49-88. 1894.
Yale, C. G. Borax. In Mineral Resources U. S. for 1889-1890, pp. 494-506.
1892.
Bull. 213—03 27 417
PHOSPHATES AND OTHER MINERAL FERTILIZERS.
Several papers on the Tennessee phosphate industry are here pre-
sented. Incidental references to the use of gypsum as a fertilizer
will be found in a paper on the salt and gypsum deposits of Vir-
ginia, on pages 406 to 416 of the present bulletin. On pages 221 to 231
will be found a discussion of the utilization of basic steel slags for
fertilizing purposes.
ORIGIN AND EXTENT OF THE TENNESSEE WHITE PHOSPHATES.
By C. W. Hayes.
VARIETIES OF WHITE PHOSPHATE.
In a former report on the Tennessee white phosphates0 the follow-
ing classification of the deposits was adopted: (1) Stony, (2) lamellar,
(3) breccia.
The first variety consists of a siliceous skeleton, the cavities in which
were originally filled with lime carbonate, but are now filled with lime
phosphate. The latter forms from 27 to 33 per cent of the rock. This
stony phosphate is found in considerable abundance in the northern
part of Perry County, on Terrapin and Redbank creeks. No attempt
has yet been made to utilize it, and unless some inexpensive method
is devised for concentrating the lime phosphate, it is too low grade to
compete with the other varieties.
The third variety, the breccia phosphate, which forms most of the
surface outcrops in the Toms Creek district, appears to be confined
almost exclusively to the surface. Its importance is small, and it is
questionable if it exists in sufficient quantity to justify the develop-
ment of machinery for separating the phosphate from the chert, even
if this separation were found to be practicable.
Only the lamellar variety, therefore, has thus far been developed.
Fortunately this variety, which is the highest grade and the most easily
prepared for market, appears to be also the most abundant. Selected
specimens of the thin plates contain 85 to 90 per cent of lime phos-
phate. The less dense, greenish material, which is associated with the
white and pink plates, contains some ferrous iron and runs slightly
under 80 per cent of lime phosphate. There appears to be no difficulty,
" Twenty .first Ann. Rept. U. S. Geol. Survey, Pt. Ill, 1901, pp. 473-485;
418
hayes.] TENNESSEE WHITE PHOSPHATES. 419
however, in getting from such deposits as are being worked on Wils-
dorfs Branch a uniform product which will run between 79 and 81 per
cent of lime phosphate.
ORIGIN OF THE DEPOSITS.
As stated in a former report, the conclusion arrived at from exami-
nation of the surface outcrops was that the lamellar variety had been
formed by deposition from solution in cavities in the limestone.
Observations recently made on more extended exposures amply con-
firm this conclusion. They show, moreover, what could not be deter-
mined from the surface outcrops, that the cavities in which deposition
took place were very extensive, forming, in fact, large caverns in the
limestone. It appears that the phosphate was deposited in a some-
what uniform and continuous layer on the floors of these caverns, in
general following their undulations, but more was deposited in the
depressions than on the elevations. Phosphate was also deposited in
less regular cavities in a limestone above the stratum in which the
main cavern formed. When this limestone was dissolved these masses
settled down with the residual clay in which they are now embedded.
During this readjustment, brought about by the solution of the lime-
stone, the phosphate was repeatedly fractured and recemented, giving
it a brecciated structure. The phosphate was doubtless deposited. in
these caverns from quiet water, but they also contained at times
rapid streams which carried sand and gravel and formed alluvial
deposits. The latter differ distinctly from those formed b}^ surface
streams under ordinary conditions. Since the stream was more or
less confined above by the roof of the cavern, as well as at the sides,
the water was sometimes under hydrostatic pressure. Under such
conditions the laws which govern ordinary stream transportation and
deposition do not apply, and the deposits possess certain charac-
teristics which clearly indicate the conditions under which they were
formed.
EXTENT OF THE DEPOSITS.
Since the lamellar variety of the white phosphate was deposited in
limestone caverns, it will be found only where the conditions were
favorable for the formation of caverns. It need not be expected above
the top of the Silurian, since the Carboniferous limestone in this region
contains so large a proportion of chert and other impurities that it
probably never gives rise to the formation of caverns. It should fur-
ther be noted that certain horizons in the Silurian limestone are much
more soluble, and hence better adapted to cavern formation, than
others. This is the characteristic of certain beds of Upper Silurian
limestone which have a granular crystalline structure and are com-
posed largely of crinoid stems. Wherever these beds are exposed by
stream cutting they are apt to be cavernous. At numerous points in
this region the streams sink and flow for considerable distances in
underground channels, and this is most often the case where the
420 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
erosion of the valleys lias reached the surface of this easily soluble
limestone. The white phosphate therefore, although its connection
with any particular bed is in a measure accidental and not essential,
as is the case with the brown phosphate, may be expected to occur in
greatest quantity at the horizon of these particular beds. Hence the
latter, identified by their peculiar fossils and physical characteristics,
will afford a guide of some value in further prospecting.
Since this phosphate was deposited in caverns, it can not be expected
to have very great lateral extent. As stated in the previous report,
it is essentially a pocket deposit, although the possibilities for exten-
sive deposits are much greater than were recognized at the time that
report was made. The examination of one deposit, no matter how
thoroughly it is exposed to view, will not enable the prospector to
make definite estimates as to the extent of any other deposit. Doubt-
less similar natural exposures may lead to inferences of some value,
but they can not be depended upon to take the place of actual pros-
pecting. Each deposit must be examined itself, and the amount of
rock which it contains, as well as its character and the depth of over-
burden, must be determined by systematic exploitation, similar to that
which has been emploj'ed by the Perry Company at Wilsdorf s Branch.
The necessity for this thorough examination of each individual deposit
can not be dwelt upon too stronglv.
Probably the greater part of the white phosphate in this district
will be obtained by open workings. The character of the overbur-
den— unconsolidated clay in which movement takes place with great
ease — is such that underground working will be attended with the
greatest difficulty. Substantial and expensive timbering would be
required wherever the phosphate was removed, and doubtless even
then a large proportion of the rock would be wasted. The specific
gravity of this rock is so much greater than that of the brown phos-
phate that a very much greater overburden can be removed with
profit for the same thickness of bed. Where the phosphate bed has a
thickness averaging 3 feet it is probable that 10 or 18 feet of over-
burden can be removed with profit while the rock commands present
prices. The phosphate which is disseminated through the overlying
clay can be saved easily with the proper plant, which should include
screens and washers. Owing to the much greater density of this rock,
the matter of drying is less important than with the brown phosphate.
It would, however, probably pay to dry the rock before shipment, and
this might be done b}^ open-air burning, or more economically with an
ordinary rotary drier.
POSSIBLE EXTENSIONS OF THE FIELD.
Considerable interest attaches to the distribution of the white phos-
phate and the possible extension of the productive territory. If the
conclusion outlined above is correct — namely, that the phosphate
deposits were accumulated in caverns in the limestone — consideration
hayes] TENNESSEE WHITE PHOSPHATES. 421
of the geologic conditions prevailing elsewhere in the district should
be of material assistance in locating other deposits.
The topography of the region between the Tennessee and Buffalo
rivers has been described in a previous report, but its main features
may be again briefly described in order to render statements regard-
ing the distribution of the deposits intelligible. For a considerable
distance the Buffalo and Tennessee rivers flow north nearly parallel
with each other, and their tributaries head upon the intervening land
and join the trunk streams very nearly at right angles, flowing east
to the Buffalo and west to the Tennessee. The tributaries of the
Buffalo are very short as compared with those of the Tennessee, so
that the divide between the two drainage basins is much nearer the
former stream than the latter. Streams of considerable size enter
the Tennessee at intervals of about 5 or 6 miles, and shorter ones
frequently intervene between these main tributaries.
Beginning in the vicinity of Perryville, the creeks of the first class
which enter the Tennessee are Spring, Lick, Toms, Roan, and Crooked,
while the streams of the second class are Parish Branch, between
Spring and Lick creeks, and Deer Creek, between Lick and Toms
creeks. These creeks are characterized by rather narrow, level valleys
and are separated by ridges rising 300 or 400 feet higher than the valley
bottoms. These ridges are simply portions of a deeply dissected
upland plateau, the altitude of which in this region is between 900
and 1,000 feet. They are capped by the Lower Carboniferous chert,
and are entirely covered with forests. While these ridges reach a
tolerably uniform elevation, the distance from their summits down
to the limestone is variable. Thus, in the ridge between Lick and
Spring creeks the chert is comparatively thin, the limestone reaching
more than tworthirds of the way from the valley bottom to the top of
the ridge. The rocks of the region are, in a general way, horizontal,
though not strictly so, and when considered in broad area they show
considerable undulations. It should be remarked that the Devonian
appears to be entirely wanting in this region, the Lower Carbonifer-
ous chert or cherty limestone resting directly upon some member of
the Silurian, usually the sparry crinoidal limestone above described.
The beds descend toward the north, and in Roan and Crooked creeks
the valleys are not cut down to the surface of the limestone. On
Toms Creek there is a dip to the west which carries the surface of
the limestone below the creek valley about 4 miles from its mouth.
It then rises so that the limestone is exposed between this point and
the Tennessee River, but again dips westward, and the surface of the
limestone is probably near the river surface at the mouth of Toms
Creek. On Roan Creek the limestone is nowhere exposed except in
the bed of the Tennessee River near its mouth. It will be readily
understood that the conditions favorable for the deposition and pres-
ervation of deposits of white phosphate are most favorable in those
regions where the surface of the limestone reaches a short distance
422 CONTBIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
above the level of the valley bottoms. Where the surface of the
limestone is too high above the valley bottoms the deposits, if they
were ever present, have been largely removed by erosion, whereas the
conditions for the formation of caverns are not present where the
limestone surface is below the level of permanent ground water in
the valleys.
On the south side of Spring Creek about three-fourths of a mile
from the Tennessee River is a small deposit of white phosphate, on
the hillside, from 75 to 100 feet above the level of the creek. The slope
is steep and covered with a thin layer of chert, through which the
limestone ledges project at many points. The deposit has been thor-
oughly prospected by means of a long trench on the hillside and also
a shaft. The chert is confined chiefly to a few inches of surface soil.
Under this is yellow clay, with fragments of limestone and some
chert, down to the surface of the solid limestone ledges. The latter is
extremely irregular, and the small cavities contain numerous bowlders
of white phosphate embedded in the yellow or blue clay. The amount
of phosphate exposed in the cut is very small, and there is no indica-
tion of a large bod}' at this point.
About 2 miles east of the above locality, on a tributary of Spring
Creek, there are on the hillside a couple of small areas carrying some
bowlders of phosphate. The slopes are covered with chert and yellow
clay, in which the phosphate is embedded. No prospecting has been
done at this point, but the limited extent of the territory covered by
the float indicates that the deposits are small in extent. Numerous out-
crops of limestone show that the solid rock is near the surface, which pre-
cludes the possibility of finding extensive deposits of phosphate here.
The next deposits to the north are on the hillside1 facing the Ten-
nessee River near the month of Parish Branch, and about a mile from
the river on the south side of this branch. Both these localities have
been thoroughly prospected. The phosphate is somewhat more abun-
dant than at the locality first described, but it is evidently limited by
the shallowness of the clay which covers the limestone. The phos-
phate appears to be of excellent quality, being made up entirely of the
lamellar variety, white or pink in color, alternating with zones slightly
more massive and somewhat porous, which have a gray or greenish
color. The phosphate occurs, so far as can be seen, only in bowlders
disseminated through the clay, but most abundant near the surface
of the limestone. It does not form a continuous layer as at Toms
Creek, and the amount of clay to be removed would be considerable
compared with the amount of phosphate obtained. These deposits
may contain a few hundred tons, but from present indications the
amount would scarcely exceed that,
The white phosphate has been found at three points on Lick Creek.
The first is about 2 miles from the Tennessee River, on the Sparks
place. It is near the top of a spur on the south side of the creek.
Tlu^ surface of the limestone is covered with a thin layer of cherty
hayes] TENNESSEE WHITE PHOSPHATES. 423
clay, and within an area#about 50 by 100 feet numerous fragments of
phosphate occur on the surface and are shown in a few shallow pits.
The smallness of the area within which the float rock is found indi-
cates that no considerable deposit occurs here, although there may
be a pocket of some depth. About 5% miles from the river, also on
Lick Creek, the phosphate shows in the roadside as a ledge in place
about 2 feet in thickness. Its lateral extent can not be determined,
but it is probably not great. Little if any float rock appears on the
surface, and the presence of the ledge would not be suspected except
for the accidental exposure in the road cutting. About a mile farther
up the creek on the south side of the valley, on Tom Young's place,
several large bowlders of phosphate occur on the cultivated hillside.
No prospecting has been done here, but the scarcity of float would
indicate that the deposit is small.
The distribution of the phosphate deposits on Toms Creek has
already been described, and thorough prospecting has failed to reveal
any considerable amount between the main deposits near the mouth
of Wilsdorfs Branch and the Tennessee River.
On Roan Creek, which is next north of Toms Creek, white phosphate
has been found at one point about 5^ miles from the Tennessee River.
A prospect pit in the creek bottom has brought to light a small amount
of the breccia variety. The phosphate forms a matrix in which par-
tially rounded chert pebbles are embedded. The latter are in every
way similar to the gravel forming the bed of the creek. As already
stated, this creek does not cut down to the limestone, except at its
mouth, and therefore the conditions favorable for the formation of
the lamellar variety are nowhere present in its valley. The same con-
ditions prevail in the next creeks to the north, Crooked Creek and
Blue Creek. Numerous leases have been taken on the farms in these
valleys, but they afford no indication whatever of deposits of phos-
phate. Occasional bowlders of chert breccia cemented by limonite are
found, and these are locally regarded as indications of phosphate.
They, of course, afford no indication whatever of the presence of such
deposits.
Little can be added to descriptions of the Toms Creek deposits east
of Wilsdorfs Branch contained in the former report. They have not
been opened to any extent, and while conditions at a few points are
favorable for the existence of extensive deposits, their extent can be
determined only by further systematic prospecting.
Some prospecting has been done in the vicinity of Beardstown at
points noted in the 1896 report. The lamellar phosphate here occurs
more or less intermingled with clay, and the test pits have not yet
revealed a continuous bed such as appears at Toms Creek. It is by no
means impossible, however, that such a bed may not occur at greater
depth than the pits have yet reached. This locality affords better
promise than any other in the district except Wilsdorf , and is worthy
of more systematic exploration than it has yet received.
THE WHITE PHOSPHATES OF DECATUR COUNTY, TENN.
By E. C. Eckel.
In several papers, one of which will be found on pages 418 to 423 of
the present bulletin, Dr. C. W. Hayes has discussed the origin, geologic
relations, and development of the white phosphates of Perry County,
Tenn., and has pointed out the areas in which careful prospecting
might reveal extensions of the producing field. The present paper
is a description of an outlying field of very promising character so
discovered.
Most of the prospecting work prosecuted after the discovery of the
Perry County white phosphate deposits was carried on in the vicinity
of the original discoveries and on the east side of the Tennessee River.
Within the last few years, however, considerable exploratory work
has been carried on in Decatur County and adjoining areas on the
west side of the river. At first, prospecting in this district was
attended with little success; but during 19()1 phosphate was discov-
ered in quantity, and the new field is rapidly becoming of importance.
The Decatur County phosphate field was visited in August, 1901,
by the writer, acting under inst met ions from Dr. Hayes. The present
paper is partly based upon the results of that examination, which was
made very soon after the first discovery of phosphate in the region.
The progress of the industry in that field during 1901 and 1902 has
been rapid, and notes on that progress have been inserted in order to
bring the present account up to date as nearly as possible.
The earliest discoveries of workable white phosphate west of the
Tennessee River were those made in 1901 by Mr. L. 11. Burke, of
Parsons, Tenn. After the discovery careful exploratory work was
carried on at other points in Decatur County, and control was secured
of all the land showing workable phosphate. The holdings of Mr.
Burke and his partner, Mr. Hughes, were transferred to the Beech
River Phosphate Company, and active work on the development of
the deposits was commenced by that company early in 1902. During
1902 about 2,000 long tons of phosphate rock were shipped from this
district to various fertilizer factories; and it seems probable that the
output of 1903 will be much larger, as machinery is now being installed
which will permit more ready handling of the rock.
The phosphates of Decatur County, so far as at present known, can
be grouped in three well-separated areas, within each of which the
phosphate occurs in isolated deposits. A small area occurs on Cub
Creek several miles north of Parsons; the second and largest area
includes deposits lying along the tributaries of Beech River between
Parsons and Decaturville, while the third area is located along Whites
424
eckbl.] WHITE PHOSPHATES OF DECATUR COUNTY, TENN. 425
Creek about 10 miles south of Decaturville. Of these, the second
area only was visited, the others not having been developed so exten-
sively. So far as can be estimated at present, the three areas together
contain some 300 to 400 acres of land on which the phosphate exists
in workable thickness and quality.
In the Beech River area the phosphate is found on the low divides
lying between the various tributaries of Beech River. Of the streams
entering from the north, only Bear Creek shows phosphate. Along
the tributaries coming from the south the phosphate deposits are more
numerous, workable quantities being found on the divides between
these streams as far east as Lost Creek. As yet no idiosphate has
been found between Lost Creek and the Tennessee River.
Occasionally the phosphate shows at the surface, but commonly it is
concealed by other materials. A typical pit in this area would show
a section, from the ground surface down, about as follows:
Typical section in the phosphate field of Decatur County, Tenn.
Feet.
Chert fragments, mingled with soil or clay 2-5
Phosphate fragments, scattered through clay . __ 1-3
Massive phosphate . _ _ 3-8
Unaltered limestone (Silurian).
The overburden, as shown in the pits visited, rarely exceeded 5 or
6 feet. It should be remembered, however, that most of these pits
are located on the lower levels of the divides, and that the thickness
of the overburden may be expected to increase as the workings get
farther into the hill; for Dr. Hayes has shown that deposits of white
phosphate, though in no sense stratified, occupy practically horizontal
positions.
At the time of the writer's visit, in 1901, the greatest thickness of
phosphate shovfoi in any of the prospecting pits was 18 feet, and the
writer then estimated the average thickness in the pits at 5 feet.
Active exploitation of the deposits has developed the fact that these
statements were too conservative rather than too nattering to the new
district. Much greater thicknesses are now shown in the workings
near Beech River, and it is said that one mine shows a thickness of
over 30 feet of workable phosphate.
The rock from this area, as mined, will average 75 to 77 per cent
bone phosphate. A series of analyses by Mr. L. P. Brown, of Nash-
ville, Tenn., shows that it varies from 70 to 85 per cent bone phos-
phate, while its content of iron oxide and alumina together varies from
less than 1 to about 3 per cent. .
Aside from the areas in southern Decatur County, above described,
it is probable that workable white phosphate deposits will be found
farther to the north. One such area is now being carefully examined,
and may prove to be worth exploitation. The black bedded phosphates
(Devonian) have also been reported from various points in northern
Decatur County, but at present no trustworthy data regarding the
value or distribution of these deposits are available.
PUBLICATIONS ON PHOSPHATES AND OTHER FERTILIZERS.
The following papers relative to natural materials used as fertilizers
have been published by the United States Geological Survey, or by
members of its staff:
Darton, N. H. Notes on the geology of the Florida phosphates. In Am. Jour.
Sci., 3d series, Vol. XLI, pp. 102-105. 1891.
Eckel, E. C. Recently discovered extension of Tennessee white phosphate
field. In Mineral Resources U. S. for 1900, pp. 812-813. 1901.
Eldridge, G. H. A preliminary sketch of the phosphates of Florida. In Trans.
Am. Inst. Min. Eng., Vol. XXI, pp. 196-231. 1893.
Hayes, C. W. The Tennessee phosphates. In Sixteenth Ann. Rept. U. S.
Geol. Survey, Pt. IV, pp. 010-630. L895.
— The Tennessee phosphates. In Seventeenth Ann. Rept. IT. S. Geol.
Survey, Pt. II, pp. 1-38. 1896.
The white phosphates of Tennessee. Trans. Am. Inst. Min. Eng.. Vol.
XXV, pp. 19-28. 1896.
A brief reconnaissance of the Tennessee phosphate field. In Twentieth
Ann. Rept. U. S. Geol. Survey, Pt. VI, pp. 63:: 638. 1899.
The geological relations of the Tennessee brown phosphates. In Science,
Vol. XII, p. 1005. 1900.
Tennessee white phosphate. In Twenty-first Ann. Rept. U. S. Geol.
Survey, Pt. Ill, pp. 473-48.-). 1901.
Ihlseng, M. C. A phosphate prospect in Pennsylvania. In Seventeenth Ann.
Rept. U. S. Geol. Survey, Pt. Ill, pp. 955-957. 1896.
Memminger, C. G. Commercial development of the Tennessee phosphates. In
Sixteenth Ann. Rept. U. S. Geol. Survey, Pt. IV. pp. 631-635. L895.
Moses, O. A. The phosphate deposits of South Carolina. In Mineral Resources
U. S. for 1882, pp. 504-521. 1883.
Orton, E. Gypsum or land plaster in Ohio. In Mineral Resources U. S.
for 1887, pp. 596-601. 1888.
Penrose, R. A. F. Nature and origin of deposits of phosphate of lime. Bul-
letin U. S. Geol. Survey No. 46. 143 pp. 1888.
Stubbs, W. C. Phosphates of Alabama. In Mineral Resources U. S. for 1883-
84, pp. 794-803. 1885.
Wilber, F. A. Greensand marls in the United States. In Mineral Resources
U. S. for 1882, pp. 522-526. 1883.
426
MINERAL PAINTS.
The following' paper on the Georgia ocher deposits represents part
of the results of field work by the Survey in that region during 1902.
On page 228 will be found a brief note on the utilization of slags in
the manufacture of pigments. Many localities still worked for min-
eral paints were described, with analyses, by Benjamin in Mineral
Resources of the United States for 1880, pages 702-714, and inci-
dental references of value occasionally occur in other volumes of that
series.
OCCURRENCE AND DEVELOPMENT OF OCHER DEPOSITS IN THE
CARTERSVILLE DISTRICT, GEORGIA.
By C. W. Hayes and E. C. Eckel.
OCCURRENCE.
Intimately associated with the brown hematite deposits of the Car-
tersville district, described on pages 238-241 of the present bulletin,
are extensive deposits of yellow ocher Avhich have essentially the same
composition, but differ in their physical characteristics. The ocher
is confined to the Cambrian quartzite, and occurs along a more or less
continuous band extending from the south side of the Etowah River
at the wooden bridge northward at least to Rowland Springs, and
probably beyond. Since it occurs in the form of a fine powder it makes
little show at the surface, and its presence is made evident only by
natural or artificial cuttings, which have removed the overlying
mantle of fragmental and residual materials. The best exposures of
the ocher occur at the south end of the wooden bridge across the
Etowah River southeast of Cartersville. Here the river, in cutting
across the quartzite ridge, has made a good natural exposure of the
beds in place. The ocher has also been extensively mined at this point,
so that abundant opportunity is afforded for studying its mode of occur-
rence. The quartzite with which it is associated has been so exten-
sively shattered by compression that its original bedding is very
difficult to determine. At this point the ocher usually forms a series
of extremely irregular branching veins, which intersect this shattered
quartzite without any apparent system. These veins frequently
427
428 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
expand into bodies of considerable size, and when the ocher is removed
rooms 6 to 10 feet in diameter are sometimes left, connected by nar-
row, winding passages. The mining of the ocher has left the point of
the ridge completely honeycombed with these irregular passages and
rooms.
The contact between the ocher and the inclosing quartzite is never
sharp and distinct, but always shows a more or less gradual transi-
tion from the hard, vitreous quartzite to the soft ore which may be
easily crushed between the fingers. The quartzite first becomes
stained a light yellow and loses its compact, close-grained texture.
This phase passes into a second, in which the rock is perceptibly
porous, having a rough fracture and a harsh "feel," and containing
enough ocher to soil the fingers. In the next phase the ocher prepon-
derates, but is held together by a more or less continuous skeleton of
silica, although it can be readily removed with a pick. The final
stage in the transition is the soft yellow ocher, filling the veins, which
crumbles on drying and contains only a small proportion of silica in
the form of sand grains.
The intermediate zone between the pure ocher and the quartzite is
usually a few inches in thickness, although it may be several feet
between the extremes, and, on the other hand, sometimes only a
fraction of an inch. When the transition rock is examined under
a microscope the character of the transition can be seen even more
clearly. The more compact portions, which are only slightly stained
with iron, are seen to be composed of a transparent gronndmass,
threaded with minute cavities which penetrate the rock in all direc-
tions and contain a tine dendritic growth of iron oxide. The latter
occurs only rarely in isolated grains, but generally in clusters of
minute grains or fibers attached to one another and branching irregu-
larly from a central stem. They have no trace of crystal form.
Passing toward the ore body, these minute passages become larger and
increase in frequency, until only a finely branching siliceous skeleton
remains, the greater part of the rock having been replaced by the
iron oxide. Under polarized light the transparent gronndmass is
broken up into an aggregate of small quartz grains penetrated in all
directions by the iron oxide. The latter does not lie between the indi-
vidual grains, but passes through them as though the groundmass were
quite homogeneous. The process of replacement is never complete,
for all the ocher contains more or less sand. When this is washed
clean from the iron oxide it is found to differ from ordinary sand
grains in having extremely irregular outlines. This sand, as might
be anticipated from the microscopic structure of the slightly altered
quartzite, is evidently composed, not of the original grains of the
rock, but of detached portions of the irregular siliceous skeleton
which in the intermediate stages of replacement holds the iron oxide
in its cavities. Aside from the silica the ocher as mined contains
HAYES AND
ECKEL.
] OCHER DEPOSITS IN CARTERSVILLE DISTRICT, GA. 429
only hydrated ferric oxide, a small amount of alumina, and a trace
of manganese oxide, the latter giving it a slightly greenish tint.
Some portions of the Cambrian quartzite contain interbedded sili-
ceous shales, and the silica in these has also been replaced to some
extent by iron oxide, producing an ocher which is inferior to that
derived from the quartzite, since it contains considerable clay — prac-
tically all the argillaceous matter originally contained in the shales.
Embedded in this ore are numerous small cubes of pyrites, or rather
limonite pseudomorphs after pyrite. These were probably an origi-
nal constituent of the shales, before the replacement occurred.
The above-described structure of the ocher and the inclosing quartz-
ite, particularly as observed under the microscope, throws consider-
able light upon its mode of origin. The forms of the residual sand
grains in the ocher and of the siliceous skeleton about its border
were evidently produced by solution. It seems probable, therefore,
that the iron oxide is a direct replacement of silica. The faulting of
the region, by fracturing the rocks, afforded favorable conditions for
the percolation of surface waters to great depths; and since the fault-
ing was doubtless accompanied by the development of considerable
heat, the region was probably characterized by numerous thermal
springs. The work of Van Hise and others has shown that, under
favorable conditions, especially under great pressure and at high
temperatures, silica becomes one of the readily soluble rock constitu-
ents. It appears that, under certain conditions, a carbonic acid solu-
tion of iron carbonate, meeting an oxidizing solution, precipitates its
iron as hydrated ferric oxide and at the same time dissolves silica.
The conditions for this reaction seem to have been present in the
Cartersville region. Water, containing in solution iron carbonate or
other ferrous salts derived from the decay of surface rocks, must have
penetrated to considerable depth, particularly through the shattered
quartzite. But in addition to this solution of iron percolating down-
ward from the surface, the open fissures probably afforded abundant
opportunity for the free circulation of water containing oxygen. The
two solutions coming in contact, the iron carbonate was oxidized and
precipitated as limonite, in the place of silica dissolved at the same
time. The solution of the silica, which is the part of the process diffi-
cult to understand, may have been assisted by the presence of alkalies
in the oxidizing solution. It was probably greatly assisted by the
heat which must have resulted from the faulting. It is also possible
that carbonic acid, in the so-called nascent state, at the point where it
is freed from one compound, may be a much more efficient solvent for
silica than in its ordinary condition.
Numerous open passages and cavities penetrating the quartzite and
the bodies of ocher are met in mining. The smaller cavities are gen-
erally lined with a crust of small quartz crystals, while the larger ones
frequently contain beautiful crystals of barite, which were probably
430 CONTRIBUTIONS TO ECONOMIC GEOLOGT, 1902. [bull. 213.
deposited after the conditions favorable for the solution of silica and
the deposition of ocher had passed. Groups of acicular crystals of
this mineral, several inches in length, are not uncommon. It also
occurs in white granular veins. The barite is called "flowers of
ocher" by the miners. It remains in the residual soil which covers
the quartzite outcrops and affords the best means of tracing the
ocher deposits. It is found at numerous points on the low quartzite
ridge north and south of the Etowah River, and prospecting at these
points lias never failed to reveal more or less extensive deposits of
ocher. A small amount of barite is annually shipped from the Car-
tersville district, the material being obtained in the course of ocher
mining.
DEVELOPMENT.
The ocher industry in the vicinity of Cartersville has developed
rapidly within the last few years. At present four mines, with their
accompanying mills, are in active operation, while two additional
properties have been sufficiently developed to be worthy of note.
Numerous undeveloped prospects are to be found within a few miles
of Cartersville, and it is probable that the industry will increase in
importance in the future.
The mines and mill of the Georgia Peruvian Ocher Company are
located about 2 miles southeast of Cartersville, on the south bank of
the Etowah River, at the wooden bridge. The deposits and work-
ings here have been described in considerable detail on a preced-
ing page of the present paper. Recently the workings have run
into large masses of ocher, and in consequence work is now mostly
carried on in open cuts, instead of the small tunnels which were for-
merly used. The mill is located at the river bank, near t lie mine.
The methods of milling the product do not differ greatly at the various
ocher plants in the Cartersville district, and a general description of
the practice followed will be given later in this paper.
The Cherokee Ocher and Barytes Company is working at a point
about 1 mile northeast of Cartersville. The workings here are all
underground and quite extensive. They have been opened up along
a slope driven down on the dip of the beds, which here dip eastwardly
at an angle of 30° or so. It is to be noted that in these mines the
ocher appears to have replaced particular beds of the quartzite, so
that it now occupies a fairly definite stratigraphic position. In this
respect the deposit differs greatly from that of the preceding com-
pany, where replacement appears to have taken place largely along-
joint planes in the quartzite, causing great irregularitj^ in the shape
and position of the resulting ocher deposits.
At the plant of the American Ocher Company, located 1 mile north-
east of the railroad bridge over the Etowah, preliminary mining work
had been done at the time of visit, and a mill was in process of con-
struction. Trenches and open cuts exposed ocher, but the under-
H1£kelND1 OCHER DEPOSITS IN CARTERSVILLE DISTRICT, GA. 431
ground work was not far enough advanced to show the relations of
the ocher to the quartzite.
The mines and mill of the Blue Ridge Ocher Company are located
about 1^ miles east of Oartersville. Considerable underground work
has been done, the deposit being opened up by slopes running down
the dip, which is to the eastward. Though the relations between the
position and shape of the ocher deposit and the bedding planes of the
quartzite are not quite so clear in this mine as in that of the Cherokee
Company, it is evident that the ocher body is fairly regular. The
manager states that a body of ocher 118 by 174 feet in area and aver-
aging 6 feet in thickness has been effectively exposed by crosscuts.
The brightest colored ocher is said to occur immediately above the
quartzite of the foot wall, a relation which exists also in the mine of
the Cherokee Company.
An ocher deposit of fair size is exposed in a railroad cut about 1
mile south of the Etowah River crossing. The Satterfield openings
are located on the north bank of the Etowah, about 100 yards east of
the railroad bridge, and the Laramore property is about 3 miles east
of Carte rsville, on the north bank of the river. At neither of these
points has sufficient work been done to give a clear idea of the extent
or relations of the ocher deposits, though ocher is shown in natural
outcrops or in small cuts at each of them.
The composition of Carters ville ocher, as compared with that of
similar products from other localities, is shown in the following table
of analyses :
Composition of natural ochers.
l.
2.
3.
4.
5.
(5.
7.
8.
9.
Fe203
SiO, . .
ALA
CaO ._.
55.84
W 20
70.00
jl3.00
I 3.60
63.30
20.00
5.00
35.00
47.00
6.00
36.67
J50. 00
42.45
30. 58
52.92
2.88
33.00
r39. 00
115.00
56. 59
30.17
3.79
2.65
MgO
1.43
Alk
0.5
co2_.
1.73
H20 ...
12.00
13.00
11.70
10.80
10. 60
11.85
14.62
11.5
1.62
1. Oartersville, Ga. Dark brown. Merrill, Rept. U. S. Nat. Mus. for 1899, p. 240.
2. East Whately, Mass. Deepest yellow. C. U. Shepard, analyst, Bull. U. S. Geol. Survey No.
126, p. 101.
3. East Whately, Mass. Deepest yellow. C. U. Shepard, analyst, Bull. U. S. Geol. Survey No.
126, p. 101.
4. East Whately, Mass. Yellowish brown. C. U. Shepard, analyst, Bull. U. S. Geol. Survey No.
126, p. 101.
5. Hancock, Berks County, Pa. Yellow brown. Merrill, Rept. U. S. Nat. Mus. for 1899, p. 240.
6. Northampton County, Pa. Deep red brown. Merrill, Rept. U. S. Nat. Mus. for 1899, p. 240.
7. Brandon, Vt. Dark brown. Merrill, Rept. U. S. Nat. Mus. for 1899, p. 240.
8. Marksville, Va. Mineral Resources U. S. for 1885, p. 528.
9. Persian Gulf. " Indian red," Mineral Resources U. S. for 1883-84, p. 926.
432 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
Milling. As above noted, the ocher milling practice at the various
plants in the Cartersville district is fairly uniform. As mined the
ocher contains a considerable quantity of coarse sands, with occa-
sional fragments of quartzite. The presence of part of these impu-
rities can be avoided by careful selection during mining, but owing
to the manner in which the deposits have originated, the ocher will
always contain some sand and quartzite, representing those portions
of the original material which have not been entirely replaced. It is
the object of the treatment described below to separate from the ocher
as much as possible of these impurities.
The ocher, brought in cars from the mines, is either dumped
directly into a log washer or dumped on a platform and shoveled into
the washer. The log washer consists of a log 12 to 20 feet in length
and S to 14 inches in diameter. Iron teeth or paddles are set along
the log in an irregular spiral. The log revolves in a trough (into
which water flows) by power . applied to gearing at one end of an
axis passing lengthwise through the log. The paddles, during the revo-
lutions of the log, break up the material (crude ocher) fed in and
gradually force the solid residue (sand, etc.) to the upper end of the
trough, while at the same time the water carries off the lighter por-
tion (containing the ocher and the finer particles of sand and clay) at
the lower end of the washer. The ocherous water is led through a
series of settling troughs 300 to 800 feet in length, set at a gentle
slope. The heavier particles are deposited in these troughs, while the
water, still carrying the fine ocher, passes on into large settling tanks.
Here it is allowed to stand until the ocher has settled to the bottom.
The overlying water, fairly clear, is then drained off through pipes
set in the sides of the tanks. The ocher in the tanks is allowed to
dry, under the ad ion of the sun, until it is solid enough to be handled.
It is then shoveled out and taken to the drying house. The final
drying takes place either on racks in the open air or over coils of
steam pipe. The latter process is of course quicker, but results in
the loss of part of the ocher, as that portion nearest the pipes is
dehydrated too much and takes a reddish tint. After drying, the
material is finely ground. The machine used for this purpose is a
Clark pulverizer or other mill of the same type (disk pulverizer).
TALC.
Various folios issued by the United States Geological Survey have
contained data relative to North Carolina talc deposits. This material
has been combined, and forms,, with additional data collected during
the last field season, the paper presented below.
TALC DEPOSITS OF NORTH CAROLINA.
Bv Arthur Keith.
One of the chief sources of talc in the United States is the series of
deposits in North Carolina. These are found almost exclusively in
the mountain region at the western end of the State, but one class of
rocks in which talc is found appears to a limited extent in the
Piedmont Plateau as well.
Talc is a hydrous silicate of magnesia, and is notable for its infusi-
bility, its softness, and its smooth, greasy feel. On account of these
characteristics its various uses have been developed. Its infusibility
fits it for gas tips and vessels which have to stand extreme heat. The
massive varieties are manufactured into pencils and articles for mark-
ing. Little of the North Carolina talc is suitable for cutting into
pencils, practically all of that character coming from the narrow belt
in Cherokee and Macon counties. When scratched or rubbed against
any ordinary surface the talc gives a white streak. Its softness also
renders it easily cut, sawed, or ground into powder. Its unctuous
nature enables its powder to diminish friction.
There are two general sources of the North Carolina talc. It occurs
as a series of lenticular masses and sheets in the blue and white
Cambrian marbles along the Nantahala, Valley, and Nottely rivers.
These rocks, termed the Cherokee marble, have a length of about 40
miles in North Carolina, and are continued in Georgia for a much
greater distance. The development of talc is much less in Georgia,
however, than in North Carolina. The second class of talc deposits
is connected with the bodies of soapstone which are found at many
more or less separated places in the Archean rocks of North Carolina*
Bull. 213—03 28 433
434 CONTRIBUTIONS TO ECONOMIC OEOLOGY, 1902. [bull. 213.
The soapstones and allied rocks are part of a great belt of such rocks
which passes through northern Georgia, South Carolina, North Caro-
lina, Virginia, and Maryland into Pennsylvania, running practically
the entire extent of the Appalachians. Although the formation is
thus very widespread, few of its areas are over a mile in length.
Many of the outcrops are to be measured by a few feet, and not many
of them cover more than an acre.
In the first or * ' marble " group of talc deposits is found the best
talc in the State. Talc appears in more than twenty-five places along
the marble belt of North Carolina, but is less common in Georgia.
The situation of these will be indicated on the maps of the Nantahala
and Murphy folios. It occurs in the shape of lenticular bodies
inclosed in the marble and varying in size from mere scales up to
masses 50 feet thick or 200 feet long. Owing to its soft nature the
talc does not withstand weathering, but readily crumbles down. It
does not outcrop, therefore, and its position is marked on the surface
only by a few weathered fragments. Thus it is impossible to deter-
mine the full extent of the talc bodies except where they have been
exposed by mining. For this same reason it is probable that many
bodies of talc have escaped observation thus far. Some of the bodies
are so extensive that they resemble sheets of sedimentary material.
This is especially the case where the talc sheets grade into the adjoin-
ing sandstone beds. They are termed "veins" by the miners, but
have none of the characteristics of true veins.
It is not probable that the talc was deposited in its present form as
a sediment, although the inclosing marbles are of that character.
The rocks of the entire region have been tremendously folded and
compressed, and most of the original materials and minerals have
been recrystallized. No sedimentary deposits of talc are known in
the Appalachians, so that it is probable that the constituents of the
talc existed in the adjacent sedimentary rocks in some other form.
Some of the beds of the marble formation now contain a considerable
percentage of magnesia in the form of the carbonate. It is probable
that the source of the magnesium carbonates and that of the hydrous
silicates are the same, both being derived from the materials of an
original sedimentary dolomite. The development of the talc in the
scales which are disseminated through the mass of the marble is thus
easily accounted for. The concentration of the talc into lenses and
sheets is, however, difficult to understand. Some of the lenses are
barely twice as long and broad as they are thick, while others are
very much attenuated and form thin sheets, as already stated. The
lenses appear to be somewhat drawn out, and pass into the marble
with very thin edges.
The color of the talc varies considerably in the different lenses and
sheets. By far the greater part of it is dull white. Of this color are
keith] TALC DEPOSITS OF NORTH CAROLINA. 435
all of the weathered, or semiweathered portions, which are near the
surface. In the talc which is secured by mining from the solid rock
light colors prevail, varying from bluish and greenish white to a
dull blue and a pale green. The freshest mineral is translucent.
This character has been lost by all of the weathered talc, which is
perfectly opaque. Much of the weathered material is also stained
with iron oxide from the ferruginous minerals in the schists which
border the marble formation. This rust coats and stains the surface
of the fragments and penetrates into their interior by cracks and
seams. It is a serious detriment to the quality of the talc, since it is
mixed throughout the latter when it is ground.
As can be readily understood from the dimensions of the talc lenses,
the quantity of the talc varies greatly. It is only by actually working
out each body or by thoroughly testing by diamond drill that any idea
of the amount can be obtained. A lens whose edge only can be seen
is as likely to be large as small. It is equally impossible to predict
where a mass of talc will or will not be found. Many of the miners
say that the talc is always overlain by a white sandstone called the
"cap rock." This is often the case, but is not the rule, for the talc
is frequently formed where there is no associated sandstone. The
talc lenses are not confined to one horizon in the marble, but may
appear between several distinct layers. Variations in the quality of
the talc are considerable, also, even in the same bod}^ of marble.
For instance, at Hewitt's mine on Nantahala River both the massive
and the fibrous varieties are found, as well as the blue, green, and
white colors. One quality and color usually predominate in a single
lens or sheet.
The texture and grain of the talc are very variable, even in the same
group of lenses, as was just stated in reference to the Hewitt mine.
The talc scattered through the mass of the marble is usually in the
shape of foliated scales. The same is true to a greater or less degree
of the thin edges of the various lenses. Some of the thicker lenses
are composed practically entirely of massive talc. This has no cleav-
age or tendency to part in one direction rather than another, and is
sawed into pencils and sheets. Most of the talc has a tendency to
break into long, thin fragments, flakes, and fibers.
Inasmuch as the methods of manufacture of the talc depend upon
its softness, any impurities which affect that quality are a detriment.
Other impurities, such as stains by iron rust and soil, were spoken of
above. These can be removed, however, in part. The principal
impediments to the working up of the talc are the associated min-
erals, mostly silicates. These are inclosed in the mass of the talc in
crystals arranged at a great variety of angles. The silicates consist
ehiefty of hornblende, tremolite, actinolite, and chlorite, all contain-
ing a certain large percentage of magnesia. There are also found
436 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213.
occasional grains of pyrite and magnetite. In localities where the
sandstone "cap rock" is found there is sometimes a mixture of the
sand grains and the talc, as if the talc was a sedimentary deposit.
The crystals of the silicates vary in size from mere needles up to
prisms with diameters of half an inch and a length of 2 or 3 inches.
These may he developed singly or arranged in radiating bunches and
groups. The greatest development of these silicates is seen 5 miles
northeast of Murphy, where the largest talc body of the region is ren-
dered worthless by them for the present. They are intergrown with
the talc in such numbers that it is not practicable to separate and
work up the talc. These same minerals are to be seen in a number
of localities crystallized in the marble where there is no talc.
The methods employed in extracting the talc lenses from the mar-
ble are very simple. For the most part the talc is obtained from pits
and shallow shafts in the soil and decomposed rock. The pockets of
talc thus encountered are usually a good deal weathered, and accord-
ingly of less value. In the large mass of talc exposed 5 miles north-
east of Murphy an open cut 50 feet square has been made, and the
amount of talc in sight is large. As above stated, however, the sili-
cate impurities there render the talc less desirable and easy to work.
The chief developments in talc mining are confined to the extreme
end of the Cherokee marble belt, on Nantahala River. Tunnels and
shafts have been sunk in several adjoining properties, extending
about a quarter of a mile along the river, and a body of talc has
been proved for a vertical extent of about 150 feet. The dip of the
strata and the included talc sheets is about 45° SE., which carries
them under the bed of the river. The talc has been found in a shaft
sunk considerably below the level of the river and is now being mined.
In the past most of the talc lias been taken out from the smaller and
more irregular lenses encountered here and there in the marble at
points up to 100 feet above the river. From various tunnels of the
Hewitt mine at this point a considerable amount of marble has been
taken out in following up the talc. The slope of the hillside follows
very nearly down the dip of the marble, and has been stripped over
a large area in the search for talc. All the talc deposits of the Chero-
kee marble are readily accessible, for a branch of the Southern Rail-
way runs within a few rods of the marble belt throughout its extent
in North Carolina.
The second, or " soapstone," group of talc deposits is of far greater
extent than the preceding group. The soapstone and talc are derived
from the metamorphism of a very basic intrusive rock and are almost
always found in connection with the areas of hornblende-gneiss and
schist. Metamorphism of these basic rocks at different places has
also resulted in the production of serpentine, dunite, and a number
Of less important rocks. Although the areas of the formation seldom
keith.] TALC DEPOSITS OF NORTH CAROLINA. 437
exceed an acre, it is customary to find several of the metamorphic
varieties associated in each area. The dunite type prevails in the
southwestern portion of the mountains in North Carolina and the
soapstone type in the northeastern. In the French Broad Valley,
about in the middle of the belt, soapstone is by far the most common,
over 80 separate areas being known below Asheville. In this district
alone are there any considerable bodies of workable talc. They are
concentrated in a belt 4 or 5 miles wide on each side of the French
Broad River between Marshall and Alexander, and will be shown in
the forthcoming Asheville geologic folio. In the forthcoming Mount
Mitchell folio, and in the Cranberry folio, now in press, many other
areas of soapstone are represented.
The talc or hydrous silicate of magnesia was formed by alteration
of a basic rock which contained originally an abundance of magnesian
silicates. In most cases, however, there were formed in addition to
the talc a number of other silicates containing magnesia, such as
tremolite, actinolite, hornblende, and chlorite. These are practically
the same minerals which occur as impurities in the talc of the Chero-
kee marble formation. As a rule, the talc is equaled or exceeded in
amount by the other silicates, and the rock formed by them is a soap-
stone. This is especially the case in Watauga and Ashe counties,
where the other silicates so predominate that the rock is often of no
value even for the uses of soapstone.
Why the talc predominates in one region and the other silicates in
another is a matter of doubt. In many places a portion of the mass
is mainly talc or a very pure soapstone, while other portions may be
filled with the silicate minerals. Where there are differences of this
kind in a single soapstone body the purer soapstone and talc are usu-
ally at the borders of the mass, being influenced in some manner by the
contact of the adjoining rocks. Besides the talc of this form, pure
talc is also found in veins a few inches in width passing here and
there through the mass of the rock. This form of the mineral is usu-
ally fibrous or foliated and free from the objectionable silicates. Talc
veins of this character seem to be of later formation than the large
bodies of talc and the soapstones. These veins are also found in the
serpentine and dunite masses, together with veins of chlorite and
asbestos.
The talc so far mined has been taken from the veins and from the
purer portions at the borders of the soapstone mass. Although the
amount of talc disseminated through the soapstone is infinitely greater,
it is not practicable to -separate it from the chlorite and other minerals
which are intermingled with it. In following the vein talc there is a
fair amount of certainty as to the product, both in quality and in quan-
tity. In the bordering bodies of talc the quantity is much greater
and can be figured upon fairly well. The quality is quite uncertain,
438 CONTRIBUTIONS TO ECONOMIC GEOLOGY, ]902. [bull. 213.
however, and the value of the talc is liable to be much lessened by the
presence of the other silicates. It is impossible to say in advance
when the quality of the talc will be thus depreciated.
The talc is almost entirely white, sometimes translucent, but usu-
ally opaque. It is probable that if work were pushed into the solid
rock the translucent material would predominate. Thus far mining-
has been confined to pits in the clay and decomposed rock. Stains
of earth and iron oxide are common in this material, as they were in
the weathered talc of the Cherokee marble. The talc now produced
varies from massive to fibrous, the latter being the most common It
is fitted only for grinding into powder. Although the amount of talc
of this class is considerable, very little is now produced, and the
industry is nearly at a standstill. Practically all the talc mined in
the State comes from the Cherokee marble.
MISCELLANEOUS NONMETALLIFEROUS MINERAL
PRODUCTS.
Several nonmetalliferous products have been discussed in the pres-
ent bulletin in conjunction with closely associated and economically
more important metalliferous ores. Under the head of lead and zinc,
for example, will be found a discussion of the fluorspar deposits of
Illinois and Kentucky (p. 205), while a newly discovered pyrite deposit
in Georgia is described in connection with the gold deposits of the
same region (p. 62).
PUBLICATIONS ON MICA, GRAPHITE, ABRASIVE MATERIALS, ETC.
The following list includes a number of papers, published by the
United States Geological Survey or by members of its staff, dealing
with various nonmetalliferous mineral products not treated separately
in the present bulletin :
Brewer, W. M. Occurrences of graphite in the South. In Seventeenth Ann.
Rept. U. S. Geol. Survey, Pt. Ill, pp. 1008-1010. 1896.
Chatard, T. M. Corundum and emery. In Mineral Resources U. S. for 1883-84,
pp. 714-720. 1885.
Davis, H. J. Pyrites. In Mineral Resources U. S. for 1885, pp. 501-517. 1886.
Eckel, E. C. The emery deposits of Westchester County, N. Y. In Mineral
Industry, vol. 9, pp. 15-17. 1901.
Emmons, S. F. Fluorspar deposits of southern Illinois. In Trans. Am. Inst.
Min. Eng., vol. 21, pp. 81-53. 1893.
Fuller, M. L. Crushed quartz and its source. In Stone, vol. 18, pp. 1-4. 1898.
The occurrence and uses of mica. In Stone, vol. 19, pp. 530-532. 1899.
Hidden, W. E. The discovery of emeralds and hiddenite in North Carolina.
In Mineral Resources U. S. for 1882, pp. 500-503. 1883.
Holmes, J. A. Corundum deposits of the Southern Appalachian region. In
Seventeenth Ann. Rept. U. S. Geol. Survey, Pt. Ill, pp. 935-943. 1896.
— Mica deposits in the United States. In Twentieth Ann. Rept. U. S.
Geol. Survey, Pt. VI, pp. 691-707. 1899.
Jenks, C. N. The manufacture and use of corundum. In Seventeenth Ann.
Rept. U. S. Geol. Survey, Pt. Ill, pp. 943-947. 1896.
Kemp, J. F. Notes on the occurrence of asbestos in Lamoille and Orleans coun-
ties, Vt. In Mineral Resources U. S. for 1900, pp. 862-866. 1901.
Martin, W. Pyrites. In Mineral Resources U. S. for 1883-84, pp. 877-905.
1886.
Parker. E. W. Abrasive materials. In Nineteenth Ann. Rept. U. S. Geol.
Survey, Pt. VI, pp. 515-533. 1898.
Peale, A. C. Natural mineral waters of the United States. In Fourteenth
Ann. Rept. U. S. Geol. Survey, Pt. II, pp. 49-88. 1894.
439
440 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 013.
Phillips, W. B. Mica mining in North Carolina. In Mineral Resources U. S.
for 1887, pp. 661-671. 1888.
Pratt, J. H. The occurrence and distribution of corundum in the United
States. Bulletin U. S. Geol. Survey No. 180. 98 pp. 1901.
Raborg, W. A. Buhrstones. In Mineral Resources U. S. for 1886, pp. 581-582.
1887.
- Grindstones. In Mineral Resources U. S. for 1886, pp. 582-585. 1887.
• Corundum. In Mineral Resources U. S. for 1886, pp. 585-586. 1887.
Read, M. C. Berea grit. In Mineral Resources U. S. for 1882, pp. 478-479.
1883.
Rothwell, R. P. Pyrites. In Mineral Resources U. S. for 1886, pp. 650-675.
1887.
Turner, G. M. Novaculite. In Mineral Resources U. S. for 1885, pp. 433-436.
1886.
Novaculites and other whetstones. In Mineral Resources U. S. for
1886, pp. 589-594. 1887.
INDEX.
A. Page.
Abrasive materials, publications concern-
ing 439-440
Adams, G. I., paper by 187-196
work done by 26; 30
Afterthoiight district, California, fea-
tures of . --.- 126
Alabama, coal fields in, area of 258
production of 258
Alden, W. C, paper by 357-360
Alaska, coal deposits in 276-283
copper deposits in 141-148
geologic work in 22
gold deposits of.. — 71-75
gold mining in 41-48
tin deposits in 92-93
Allegheny Valley, Pennsylvania, coal
beds of 272-274
Allen, E. T., chemical determinations
by 114,115
Almy, T. J., cited.... 39
Alum, manufacture of, from iron slag. . . 229
American Creek, Alaska, gold mining on . 48
Amsterdam oil pool, Ohio, developments
of 342-344
Anglesite, deposits of, Kansas 200
deposits of, Missouri 200
Utah.. 114
Anvik River, Alaska, coal bed on 282
Anvil Creek, Alaska, gold deposits in 45
Appalachian region, copper deposits in. 181-185
geologic work in 23
Arizona, cement materials in 372-380
coal beds in 379
copper deposits in 133-140, 149-157
gold deposits in 140
work in 23-24
Arkansas, asphalt deposits of 353-355
coal fields in, area and production of. 258
lead and zinc field of, development of. 188
geology of 189-192
history of 187-188
ore deposits of.. 192-196
position of 187
production of 188
work in 26,30
Ashley, G.H., work done by 30
Ashley, G. H., and Fuller, M. L., paper
by 284-293
Asphalt, analyses of.. 354
deposits of, Arkansas 353-355
Indiana 333
origin and distribution of 296-305
investigations of 30
publications concerning, list of 356
Page.
Asphaltene, characters of 299-300
Attapulgus, Ga., fuller's earth beds at. _. 392-
393,394
B.
Bain, H. F., cited 196
work done by 30
Bain, H. F., and Van Hise, C. R., paper
by, title and notice of 20
Baker Flats, Alaska, gold prospects on. . . 55
Balaklala mine, California, ore bodies of. 132
Bancroft, H.H., cited... 107
Barite, deposits of, Kentucky. 212
Barrell, Joseph, and Weed, W. H., paper
by, title and notice of 21
Bauxite, investigations of 29
Bayley, W. S., work done by 30
Bear Mountain, California, limestone
beds near 365
Beaumont clays, Texas, character of 346
Beaver Valley, Pennsylvania, coal beds
of. 275
Becker, G. F., cited 57,60
Beech River, Tennessee, phosphate de-
posits on 425
Berea grit, structure of 339-340
Big Creek shaft, Pearl, Colo., copper
oresat 164-165
Big Horn shaft, Pearl, Colo., copper de-
posits at 168
Bingham, Utah, ore deposits at 105-122
Bingham Canyon mining district, Utah,
geography of 106-107
geology of 109-122
history of 107-109
ores of 113-118
placer deposits of 119-120
production of 109
Birch Creek region, Alaska, mining in. . . 47
Bisbee, Ariz., copper deposits at, investi-
gations of 24,149-157
Bisbee beds of Arizona, features of 150-151
Bitterroot Range, geology of 66-70
work in 26
Bitterroot Range and Clearwater Moun-
tains, Montana, mineral depos-
its of 66-70
Bituminous rock deposits, origin and dis-
tribution of. 296-305
Black Diamond district, California, fea-
tures of 130-131
Black Hills, work in 27-28
Blake, W. P., cited 296
Blatchford coal mine, Yukon River,
Alaska, conditions at 281
441
442
INDEX.
Page.
Blende, deposits of - --- 193-196
Blewett, Wash., gold mines near 78-79
Bine Creek, Tennessee, phosphate depos-
its on 423
Blue Mountains, Oregon, ore deposits in. 22
Bonanza claim, Alaska, copper ores at. 144-145
Bonanza Creek, Alaska, coal beds on. - . 277-278
Borate, Cal., borax deposits at. 403
Borax, deposits of, California - 401-405
publications concerning - - - 417
Boston mines, Cuba, manganese deposits
at 253-255
Boulder, Colo., oil field near, geology
of. 322-325
oil field near, oil-bearing strata of. . 327-328
production of - 331-332
shooting of wells in 329-330
source of oil of . 330-331
Boulder Creek, Washington, gold-mining
gravels on 76-77
Boundary Creek, Alaska, gold mining on. 47-48
Bout well, J. M., papers by 31^0,105-122
work done by.. 24,25,64,133
Bradshaw quadrangle, Arizona, work in. 23-24
Branner, J. C, cited 196
Brick, manufacture of, from iron slag,
methods of.... 224-225
Brick clays, deposits of, Mississippi 382 391
Tennessee. 382-391
Broadford, Va„ gypsum deposits near 410
Brock Mountain, California, limestone
beds at 365
Brooks, A. H., cited 142,148,269
paper by, title and notice of 22
papers.by.. 41-48. 92-93
Buffalo Hump mining district, Montana,
mineral deposits in. 68 69
Buhner Creek, Alaska, tin deposits on 92-93
Bulletins of U. S. Geological Survey,
character of 10
Bully Hill district, California, country
rocks of, analyses of 127
location and extent of 126
ore bodies of 138-129
Bush coal mine, Yukon River, Alaska,
coal of 281
Butte, Mont., ore deposits at 170-180
work on copper mines at 26-27
Butte mining district, Montana, copper
deposits of 170-180
development of 171-173
geology of.. 172-175
situation of 170-171
C.
Calamine, occurrence of, Kansas 200
Missouri _ 200
Calcite, deposits of, Kentucky 212
California, bituminous deposits in 302-304
borax deposits of 401-405
coal fields in, area and production of. 258
copper deposits of 123-132
iron ores of 219-220
limestone beds in.. 365
petroleum fields of 306-321
work in 25,30,64-65
Page.
California Gulch, Alaska, copper deposits
on 147
Camp Creek, Alaska, copper deposits on. 148
Campbell, M. R., paper by 270-275,401-405
work done by 30
Cantwell River, Alaska, coal beds on 280
Cartersville, Ga., ocher deposits near.. 427-432
geology of region near 233-237
iron ores near 233-242
manganese ores near 232
Cassiterite, deposits of, Alaska 93
Texas 99-102
Cement, deposits available for manufac-
ture of, Arizona 372-380
publications concerning, list of 381
Cement, Portland, composition of.. 223-224,377
Cement, sand, composition of 373
costof. 376-377
tests of 373-375
Cement, slag, composition of 223, 224
manufacture of .'.... 221 , 223
Cerussite, deposits of, Kansas 200
deposit of, Missouri 200
Utah 113,114
Chalcopyrite, i >< ;curr< -nee of 200
Chatham Hill, Virginia, gypsum deposits
near 410
Chena River, Alaska, gold mining near. . 47
Cherokee marble, North Carolina, talc
deposits in 433
Chesna River, Alaska, gold deposits on.. 73-74
Chicago, 111., building stone near 357-360
Chiekamauga limestone, Tennessee,
marble beds in 366-370
Chisana River, Alaska, copper deposits
near 148
Chistochina gold fields, Alaska, geog-
raphy of 71
geology of 71-72
gold deposits of 72-74
origin of 74-75
mining in 48
Chromium, publications concerning, list
of 104
Clark, W. B., cited 230
Clays, deposits of 382-400
investigations of 30
publications concerning, list of 400
Clays, brick, Tennessee. 382-391
Clays, stoneware, Tennessee 382-391
Clearwater Mountains, geology of 66-70
work in 26
Clements, J. M., work done by 24,130,149
Clifton, Ariz., copper deposits at, develop-
ment 133-134
copper deposits at, features of 135-140
gold deposits at 140
Clifton-Morenci quadrangle, Arizona,
work in 24
Clinch Mountain, Tennessee, marble beds
near 366-367
Coal, analyses of 286
classification of, as fuel 2(53-266
deposits of , Alaska 276-283
Illinois 284-293
Indiana 284-293
INDEX.
443
Page.
Coal, distribution of 257-259
fuel ratios of, table showing 266
publications concerning, list of 294-295
Coal, anthracite, deposits of 257, 260
Coal, bituminous, deposits of, Pennsylva-
nia, geologic features of 270-275
Coal Creek, Alaska, coal beds on 277-278
gold mining on 48
Coal fields of the United States, area of. 257-259
Carboniferous 260-261
Cretaceous 262-263
development of 267-269
distribution of 257-259
geologic relations of 259-266
investigations of 29-30
markets for.... 267-269
production of... 267-269
Tertiary.... 263
Triassic 261-262
Coalinga district, California, petroleum
deposits in '. 306-308
Collier, A. J. , papers by 49-56, 276-283
work done by. 92
Colorado, asphalt deposits in 301-302
coal fields in, area and production of. . 258
copper deposits of 163-169
ore deposits in, publications concern-
ing 19-20,21
petroleum deposits in 322-332
work in... 25-26,30
Colorado Creek, Alaska, gold mining on. . 48
Columbia sands, Texas, character of 346
Colvin, W., cited 58
Connecticut, tungsten minerals in 20, 98
Cook Inlet region, Alaska, gold mining
in 48
Copper, deposits of, Arizona 23-24, 133, 140
deposits of, California 25, 1 23-132
Colorado 163-169
Maryland 183
Montana 26-27,170-180
New Jersey 182-183
North Carolina 184-185
Tennessee 185
Utah. 31-48,105-122
Virginia 183-184
Wyoming 28, 94-97, 1.58-162
publications concerning, list of 186
Copper ores, platinum in, Wyoming 94-97
Copper King claim, Alaska, ores at 146-147
Copper King Mountain, Arizona,ores of. 1:39-140
Copper Queen claim, Pearl, Colo., copper
deposits at 167-168
Copper Queen mine, Arizona, features
of... 152-156
Copper River Basin, gold deposits in.. 48,71-75
Coronado mine, Arizona, ores of 139
Cranberry district, North Carolina-Ten-
nessee, iron ores in 243-246
Crider, A. F., work done by 205
Cristo, Cuba, manganese deposits near. 252, 253
Crooked Creek, Tennessee, phosphate de-
posits on 423
Cub Creek, Tennessee, phosphate deposits
on 424
Cuba, manganese deposits of 251-255
D. Page.
Daggett, Cal., borax deposits near 402,403
Dahlonega district, Georgia, geology of.. 58-59
gold and py r ite deposits of 57-63
literature of 57-58
Dale, T. N., paper by 361-364
work done by 29
Dall River, Alaska, coal beds on. 278
Dana, J. D., cited 298,299,300
Death Valley, California, borax deposits
in.. 403-405
Diller, J. S., papers by 123-132,219-220,365
work done by 25,30
Ditney quadrangle, Indiana, coal beds
in.. 284-290
Dolomite, occurrence of, Kansas 200
occurrence of, Missouri 200
Douglas, Ariz., copper production at 153
Douglas, E. M., work done by 31
Drew mine, Yukon River. Alaska, coal
mining at 279
Dumble, E. T., cited^ 151
Duryee, Edward, paper by 372-380
E.
Eckel, E. C, papers by 57-63, 221-231,
382-391, 406-416, 424-425
work done by 29,57-63
Eckel, E. C, and Hayes, C. W., papers
by.. 233-242,427-432
El Paso, Tex. , tin deposits at 99-102
tin deposits at, development of 101-102
geological structure of 99-100
ores and veins of 100-101
Elaterite, features of •_ 299
Eldridge, G. H., cited 324
papers by 296-1321
work done by 29,30
Elkhorn mining district, Montana, report
on ore deposits of 21
Elliott Creek, Alaska, copper mining
on 145-146
Elmhur st, 111. , building stone at 358
Emmons, S. F., cited 36,111,112,120
paper by, on ore deposits, title and
notice of 18
papers by 15-28,94-97
work done by 27-28
Enargite, deposits of, Utah 114
Encampment copper region, Wyoming,
mineral resources of 158-162
Etowah River, Georgia, ocher deposits
on 4:30-431
Eureka Creek, Alaska, placer gold on 51,55
F.
Fenneman, N. M., paper by 322-332
Felsite, deposits of, Kentucky 212
Fertilizers, manufacture of, from steel
slag, methods of 225-227
investigations of deposits of 418-426
publications concerning 426
Florida, fuller's earth deposits in 392-399
work in 29,30
Fluorite, deposits of, Kentucky 211 212
Fluorspar, deposits of, Kentucky ... 26,205-213
444
INDEX.
Page.
Folis, F. J., work done by 205
Fortymile River, Alaska, placer deposits
on 47
Fourth of July Creek, Alaska, gold min-
ing on.
48
Franklin furnace, New Jersey, zinc and
manganese deposits at 214-217
Franklinite, deposits of, New Jersey 214
Friendsville coal, Illinois, character and
thickness of 292-293
Frio,clays, Texas, character of 346
Fuller, M. L, paper by 333-335
work done by 30
Fuller, M. L., and Ashley, G. H., paper
by 284-293
Fuller's earth, analyses of 393,
395.396,397,398-399
deposits of, Florida 392-399
Georgia.. 392-399
publications concerning, list of 400
Furnaceville, Cal., limestone beds near . . 365
Galena, deposits of, Arkansas 193-196
deposits of, Kansas 200
Kentucky 212
Missouri 200
Utah.. 114
Gas, natural, deposits of, Indiana 334-335
publications concerning, list of 356
Gas fields, investigations of 30
Geologic folios, character of 1()-11
list of ..'. 11-13
Georgia, coal fields in, area and produc-
tion of . 258
fuller's earth deposits in 392-399
gold and pyrite deposits of 57-63
iron ores of _ 233-242
manganese deposits in 232
ocher deposits in 427-432
work in :{<)
Girty, G. H., cited 109
Glass, manufacture of, from iron slag ... 230
Glenn Creek gold mining district, Alaska,
geology of. 50-51
location of 47,49-50
placers of 51-55
production of 52-53
Globe quadrangle, Arizona, work in 24
Gold, deposits of, Alaska 41-56, 71-75
deposits of, Arizona 140
California 25
Colorado 25-26
Georgia 57-62
Idaho 26
Montana 66-70,88-89
Nevada 27,81-87
Utah 31-40, 115, 116, 119-120
Washington 76-80
work on 31-91
publications concerning, list of. 19-28,90-91
Gold and pyrite deposits of the Dahlonega
district, Georgia, paper on 57-63
Gold Hill, N . C . , copper deposits at 184
Gold King claims, Pearl, Colo., copper
deposits at 107
Page.
Gold Mountain district, Nevada, mining
in 87
Gold Run, Alaska, placer gold on 51,52-53
Goodyear claim, Alaska, copper ores at. . 145
Grand Junction, Ten::., clay pits at 384-386
Graphite, publications concerning 439-440
Gravel, deposits of, Illinois 360
Greenbrier limestone, Virginia, section of 410
Griswold, W. T., paper by. 336-344
work done by 30
Grand Republic shaft, Pearl, Colo., cop-
per deposits at ... 168-169
Gulf Coastal Plain oil field, geology of. 346-347
location of 345
oil pools of .... 348-351
topography of 345-346
Gypsum, analyses of 411,412
deposits of, Virginia 406-416
publications concerning, list of 417
Hall Rapids, Yukon River, Alaska, coal
bed at. 282
Hardin, N. D., analysis by 411
Hatchettite, composition of 298
Hawkey e claims, Pearl, Colo., copper de-
posits at 165
Hayes, C. W., cited 141,148
papers by 29, 232, 257-269, 345-355, 41S-423
work done by.. 29,30
Hayes, C. W., and Eckel,E. C, papers by. 233-
242,427^32
Hematite, deposits of, Georgia 237-241
deposits of, North Carolina 245-246
Tennessee 245-246
Hennepah district, Nevada, gold deposits
in.. 81
Hess Creek, Alaska, coal beds near 279
Hico, Tenn., clay pits near 388
Hidden, W. E., cited.. 94
Hillebrand, W. F., chemical determina-
tions by 114
Hirz Mountain, California, limestone beds
at 365
Hobbs, W. H., paper by.. 98
paper by, title and notice of 20
Holland coal, Indiana, character and
thickness of 288,289
Holly Springs, Miss. , clay pits at 384
Holston marble, Tennessee, occurrence
of... 366-370
Holston River, North Fork of, Virginia,
salt and gypsum deposits on .406-416
Hopedale oil pool , Ohio , developments of . 342-343
Houchin Creek, Indiana, coal near 287
Howard, G. W., analyses of asphalt by. 353-354
Hubnerite, occurrence of 103
Humboldt, Tenn . , clay pits near 391
Hunter Creek, Alaska, gold mining on... 55
Hydrocarbons, classification of 296-298
general features of 298-300
Idaho, coal fields in, area and production
of 258
work in . „„ 26
INDEX.
445
Page.
Illinois, building stone in 357-360
coal in I: 292-293
coal fields in, area and production of.-- 258
Indiana, asphalt deposits in -W
coal in - - 284-292
coal fields in, area and production of. 258
gas, natural, in 334
petroleum deposits in 333-334
work in - 30
Indian Territory, asphaltite deposits in . 300
brea deposits in - 301
coal fields in, area and production of. 258
work in y0
Iowa, coal fields in, area and production
of. 258
Iron ores, deposits of, California. 219-220
deposits of, Georgia 233-242
Minnesota 247-250
North Carolina 243-246
Tennessee.. 243-246
publications concerning 30, 256
Iron Mountain mine, California, ore bod-
ies of 131-132
Iron slag, analyses of 222, 224, 225
utilization of.... 221-231
Irving, J. D., work done by 24, 25, 27, 31
J.
Jack. See Sphalerite.
Jackson, Tenn., clay pits near 388,390-391
Jaggar, T. A., work done by 23
Johnson, H. R., work done by 66
Joplin district, Missouri-Kansas, geology
of 198-199
lead and zinc deposits of 197-21)4
location and topography of 197-198
ore deposits of 200-204
Kansas, coal fields in, area and produc-
tion of.. 258
lead and zinc deposits in 197-204
Keith, Arthur, papers by . 2413-246, 366-370, 433-438
work done by.... 29,105
Kemp. J. F., paper by, title and notice of. 22
Kennedy, "William, work done by 30
Kennett, Cal . , limestone beds at 365
Kentucky, bituminous sandstones in 301
coal fields in, area and production of. 253
fluorspar deposits in 205-213
lead deposits in. 205-213
work in 26,30
zinc deposits in 205-213
Kern River oil field, California, features
of. 310-312
Ketchikan mining district, Alaska, geo-
logic work in 22
Keystone claim, Alaska, copper ores at__ 146
Kletsan Creek, Alaska, copper deposits on 148
Knight, W. C, cited 94,95
Knox viile, Tenn . , marble near 368, 369-370
Kotsina River, Alaska, copper deposits
on 145-146
Koyukuk River, Alaska, coal bed on 282
gold mining on _ , ...... 46-47
L. Page.
Lafayette sands, Texas, character of 346
La Graciosa Hills, California, oil deposits
in 313
Lake Superior iron district, work in. 30,247-250
Lead, deposits of, Arkansas 26, 187-196
deposits of, Kansas 197-204
Kentucky 205-213
Missouri 26,197-204
Montana 67
Ozark region, report made on 20
Utah 31-40
work on 26,30
publications concerning, list of 218
Leith, C. K., paper by 247-250
work done by. 30
Lemont, 111., building stone at 357-358
Lick Creek, Tennessee, phosphate depos-
its on 423
Lignite, deposits of 259, 292
publications concerning 294-295
Limestone, analysis of 359
deposits of, Illinois 357, 358-360
Limonite, deposits of , Georgia 238-241
Lindgren, Waldemar, cited 96, 97
paper on metasomatic processes in
fissure veins by, title and no-
tice of 18
papers by 64-65, 66-70, 133-140
work done by , 22, 24, 25, 26
Lippincott, J. B., work done by .. 372
Lizzie claim, Pearl, Colo., copper deposits
at 165
Longfellow mine, Arizona, features of . _ 138
Los Angeles, Cal., oil field near 318-319
Louise claim, Alaska, copper ores at 145
Louisiana, petroleum deposits in 345-352
work in 30
M.
Macadam, stone available for, Illinois _ 358-360
McBeth, J. F., work done by 31
McCloud River, California, limestone beds
along 365
McKenzie, Tenn., clay pits near 389
McKinley Creek, Alaska, gold deposits on 55
McKittrick district, California, oil fields
of 308-309
Magnetite, deposits of, Georgia 237
deposits of, North Carolina 243-245
Tennessee 243-245
Manganes3, deposits of , Cuba 251-255
deposits of, Georgia 232
New Jersey... 214-217
publications concerning, list of 256
Marble, beds of, Tennessee 366-370
investigations concerning. 29
Marcasite, occurrence of, Kansas 200
occurrence of, Missouri 200
Marcasite and pyrite, bulletin on, title
and notice of 20
Martinsburg, "W. Va., slate beds near.. 363-364
Maryland, coal fields in, area and produc-
tion of 258
copper deposits in 183
Marysville district, Montana, geologic;
features of 88
446
INDEX.
Page.
Marysville district, Montana, 1< >cat i< m of. 88
ores of- 89
Maxwell, H. V., cited . . - - — - 58,60
Maynardville, Tenn., marble near 368
Medicine Bow Range, Wyoming, geology
of - 95-96
platinum in copper ores in 944)7
topography of 95
Mendenhall, W. C, cited 278
paper by. -- --- 71-75
Mendenhall, W. C, and Schrader, F. C,
paper by 141-148
Mesabi district, Minnesota, iron ores in 247-249
Metalliferous ores, investigations of 15-28
Metcalf , Ariz . , copper deposits at 138
Mica, publications concerning, list of., 439-440
Michigan, coal fields in, area and produc-
tion of.. -- 258
iron deposits in. 249-250
Middleway , W. Va., slate beds near 364
Miller Gulch, Alaska, gold deposits on... 72-73
Millersburg, Ind., coal beds near 285, 288
Mine Hill, Franklin furnace, New Jer-
sey, zinc ores at.. 214-217
Mineral resources, reports on, character
of 14
Mineral wool, manufacture of, from iron
slag — - 227-228
Minook Creek, Alaska, coal beds on 279-280
gold mining on 50,55
Mission Creek, Alaska, coal-bearing rocks
near 277
Mississippi, clay deposits of 382-391
Mississippi Valley, work in 26,30
Missouri, bituminous deposits in 301
coal fields in, area and production of. 258
lead deposits in 20,197-204
work in 20,30
zinc deposits in 20, 197 204
Mohawk Mining Company, operations of 78
Monographs of U. S. Geological Survey,
character of 10
Monongahela Valley, Pennsylvania, coal
beds of.. 271-272
Montana, coal in (57
coal fields in, area and production of 258
copper deposits in 67,68,17(1 L80
gold in 67-70,88-89
lead deposits in 67
ore deposits in 21, 66-70
silver in 67-70
work in 26-27,30
Monte Cristo, Wash. , ore deposits at 22
Monte Cristo Creek, Alaska, copper de-
posits on 147
Moose Mountain district, Canada, iron
oresin 250
Morenci, Ariz., copper deposits near... 133-140
gold deposits near. 140
Mosquito Creek, Florida, fuller's earth
bedson ._ 395
Mount Wrangell region, Alaska, copper
deposits of 141-148
explorations of 141-142
geography of 141-142
geology of 142-144,147
Page.
Mount Zirkel shaft, Pearl, Colo., copper
deposits at 166-167
Mule Mountains, Arizona, geology of . . 149-150
Mundic. See Marcasite and Pyrite.
Murray, J. R., cited.... 119
N.
Nabesna River, Alaska, copper deposits
near 147-148
Nation River, Alaska, coal beds on. 278
Nebraska, coal fields in, area and produc-
tion of 258
Neocene rivers of the Sierra Nevada,
paper on 64-65
Nevada, gold mining in 81-87
tungsten ore in 103
work in 27
New Jersey, copper deposits in 182-183
manganese deposits in 214-217
zinc deposits in 214-217
New Mexico, coal fields in, area and pro-
duction of 258
Nickel, publications concerning, list of . . 104
Nicolai copper mine, Alaska, features of. 144
Nitze and Wilkens, cited. 57
Nohatatiltin coal bed, Alaska, character
of coal from 280
North Carolina, coal fields in, area and
production of 257
copper deposits in.. 184-185
iron oresin 243-246
talc deposits of 433-438
Nulato, Alaska, coal bed at 281
O.
Oak Ridge, California, oil field near 317-318
( >cher, analyses of 431
deposits of, Georgia 427-432
manufacture of, processes employed
in 432
Ogdensburg, N. J., zinc mines at 214,217
Ohio, coal fields in, area and production
of. 258
petroleum deposits in 336-344
Oil. See Petroleum.
Oil fields, investigations of 30
Oil City petroleum field, California, fea-
tures of 307-308
Omega Creek, Alaska, gold indications on 50,55
Ophir Creek, Alaska, gold deposits on . . . 46
Oquirrh Range, Utah, geography and
geology of 106-112
Oregon, coal fields in, area and production
of... 258
ore deposits in 22
work in 30
Ozark region, work in 30
Ozocerite, composition of 298
P
Pacific coast, work on 30
Paint stock, manufacture of, from iron
slag.. 228-229
See also Ocher.
Palache, Charles, work done by 23
Paris, Tenn., clay pits near
INDEX.
447
Page.
Park City mining district, Utah, climate
of 33
geography of 32-33
geology of 35^0
history of. 34-35
igneous rocks in . 37
mining operations in 38-39
ores of... 39-40
production of 35
timberin 33
water in 32
Patoka quadrangle, Indiana-Illinois, coal
in 290-293
Paving blocks, manufacture of, from iron
slag, methods of 224
Pearl, Colo., copper deposits at 163-169
Peat, publications concerning 294-295
Pedro Creek, Alaska, gold mining on 47
Penfleld and Wells, cited 94
Penrose, R. A. F., cited 232
Pennsylvania, coal fields of, area and pro-
duction of 257, 258, 260
coal fields of, work in 270-275
slate beds in 361-364
work in 30
Peshastin mining district, Washington,
gold deposits of... 78-79
Petersburg coal, Indiana, analyses of 286
character and thickness of 285-286, 289
Petrolene, features of 299
Petroleum, accumulation of, conditions
favoring 347-348
deposits of, California 306-321
Colorado. 322-332
Gulf Coast, character and utiliza-
tion of 351-852
Indiana 333
investigations of. 30
Ohio 336-344
publications concerning, list of 356
Pickart coal mine, Yukon River, Alaska,
conditions at. 280-281
Piney Fork oil district, Ohio, develop-
ments in 341
Pinson, Tenn., clay pits near 386-388
Pioneer Creek, Alaska, gold deposits on . 50, 55
Phosphates, deposits of, Florida, investi-
gations of 29
deposits of, Tennessee, investigations
of 29,418-425
origin of 419
publications concerning, list of 426
Phosphate rock, analysis of 425
Placer gold, Alaska, distribution and
source of 41-44
Platinum, deposits of, Wyoming 94-97
pu blications concerning 22, 104
Plasterco, Va. , gypsum deposits at 412
Ponupo mines, Cuba, manganese deposits
at 253-255
Porcupine district, Alaska, gold mining
in.... 48
Pratt, N. P., acknowledgments to 63
Professional Papers of U. S. Geological
Survey, character of 10
Puente Hills, California, oil field in .... 319-321
Page.
Purington, C. W., work done by 19
Pyrite, analysis of. 63
deposits of, Georgia 62-63
Kansas 200
Missouri 200
Utah H3-114
Pyrite and marcasite, bulletin on, title
and noticeof 20
Q.
Quicksilver, publications concerning, list
of 104
Quincy, Fla., fuller's earth beds near .. 396-397
R.
Railroad ballast, use of iron slag for . . . 230-231
Rambler mine, Wyoming, platinum at. . . 94-97
Rampart, Yukon River, Alaska, coal beds
near 280
gold miningat 47
Ransome,F.L., paper by 149-157
bulletin by, title and notice of 19
paper by, title and notice of 21
work done by 19,21 24
Redbank Creek, Tennessee, phosphate de-
posits on 418
Redding region, California, Afterthought
district of 126
Black Diamond district of 130-131
Bully Hill district of 126-130
copper deposits of 123-132
Iron Mountain district of 131-132
iron ores of 219-220
limestone beds in 365
rocks of 123-126
Rhode Island Creek, Alaska, gold indica-
tions on 50,53-54
Rice Mountains, Colorado, report made
on ore deposits of 21
Richardson, Clifford, cited 297,299
Richardson, G. D., cited 274
Ries, Heinrich, analyses by 393, 395
cited 395
work done by 30
River Junction, Fla., fuller's earth depos-
its near . 394-395
Riverside, Ariz., cement rocks near 378
Road metal, use of iron slag for 230
Roan Creek, Tennessee, phosphate depos-
its on. 423
Robertson, W. B., acknowledgments to.. 408
Rock, A.M., work done by 24, 149
Rock Creek coal, Indiana, character and
thickness of 288,200
Round Top claim, Pearl, Colo., copper de-
posits at 167
Rubble, stone available for, Illinois 358-360
Ruby Creek, Alaska, gold mining on 55
S.
Sag Bridge, 111., paving stone at 358
Sahlin, A., cited... 228
Salt, analyses of.. 413-414
deposits of, Virginia 406-416
publications concerning, list of 417
448
INDEX.
Page.
Salt, rock, analyses of 413-414, 415-416
Salt Creek, Alaska, coal beds on 279
Saltville, Va., gypsum deposits at 411-412
salt wells at. 412-414
San Carlos dam site, Arizona, cement
rocksnear 378
coal beds near 379
Sand, deposits of, Illinois 360
San Juan region, Colorado, ore deposits in 19
Santa Clara River, California, oil fields
near.. 315-318
Santa Susana Mountains, California, oil
fields in 317^318
Santiago, Cuba, manganese deposits of. 251-255
Schrader, F. C, cited 282
Schrader, F. C.,and Spencer, A. C, cited. 142
Schrader, F. C, and Mendenhall, W. C,
paper by 141-148
Seaboard Air Line Railway, Florida, sec-
tion on 397
Seaman, A. E., cited.. 250
Seventymile River, Alaska, coal-bearing
rocks on 277
gold mining on 48
Seward Peninsula, Alaska, gold deposits
on 44-46
Shannon mine, Arizona, ores of 138
Sbaser Creek, Washington, gold deposits
on.. 78
Shasta King mine, California, ore bodies
of 132
Sierra Madre shaft. Pearl, Colo., copper
oresat 165
Sierra Nevada, work in 25, 64-65
Silicate cotton, manufacture of, from iron
slag 227-228
Silver, deposits of, Idaho 26
deposits of, Nevada 81-87
Utah 31^0,116
Washington 80
publications concerning 19-28, 90-91
Silver Peak district, Nevada, gold min-
ing in &5-86
Silverton quadrangle, Colorado, ore de-
posits in 19
Slag, iron, analyses of 222, 224, 225
Slag cement, composition of 222-223
manufacture of 221-223
Slate, beds of, Pennsylvania 361-364
West Virginia 361-364
investigations concerning.. 29
Slate Creek, Alaska, gold deposits on. . 55, 72-73
Slatington, Pa., slate beds at 361-363
Smith, F. B., cited.. 103
Smith, G. O., paper by 76-80
work done by 30
Smith, W. S. T., papers by. 197-204, 210-213
work of 26-30
Smithsonite, occurrence of, Kansas 200
occurrence of, Missouri 200
Soda, publications concerning 417
Soapstone, occurrence of, North Caro-
lina. 436-437
South Dakota, coal fields in, area and
production of 258
work in 27-28
Page.
Southern Klondike district, Nevada, gold
mining in . 86-87
Spar. See Dolomite.
Spellacy oil pool, Ohio, developments in . 341-342
Spencer, A. C, papers by 158-161,251-255
work of 28
Spencer, A. C, and Schrader, F. C, cited 142
Sperrylite, occurrence of 94-97
Sphalerite, deposits of, Kansas 200
deposits of, Kentucky 212
Missouri 200
Spring Creek, Tennessee, phosphate de-
posits on 422
Spurr, J. E., cited.. 50,51
paper by.. 81-87
paper by, title and notice of 22
work done by 27
Steel slag, utilization of 221-231
Sterling Hill, Ogdensburg, N. J., zinc de-
posits at 217
Stevenson, J. J., cited 407
Stoek, H. H., cited 265,267
Stokes, H. N., bulletin by, title and notice
of 20
cited 114
Stone, building, occurrence of, California. 365
occurrence of, Illinois 357-360
Tennessee 366-370
publications concerning, list of 371
Stoneware clays, Mississippi 382-391
Tennessee 382-391
Storrs, L. S., cited 262
Stose, G. W., work done by 66
Summerland, Cal., oil field near. 313-315
Sunset oil field, California, features of. 309-310
Survant coal, Indiana, character and
thickness of 287,289
Swauk Creek, Washington, gold-bearing
gravels on 76-77
Swauk mining district, Washington, gold
deposits of 76-78, 79-80
Swede claims, Pearl, Colo., copper depos-
its at 165
T.
Taff, J. E., work done by 30
Tahkandit River, Alaska, coal beds on. . . 278
Talc, colors and textures of 434-435
deposits of, North Carolina 433-438
mining of, methods of 436
occurrence of, modes of. 434
Tallahassee, Fla. , fuller's earth beds near. 397
Tennessee, clay deposits of 382-391
coal fields in, area and production of. 258
copper deposits in 185
iron ores in 243-246
marble beds in 366-370
phosphate deposits in 418-425
work in 30
Terrapin Creek, Tennessee, phosphate de-
posits on 418
Tetrahedrite, deposits of, Utah.. 114
Texas, bituminous deposits in 301
coal fields in, area and production of. 258
ore deposits in, notice of bulletin on. . 20
petroleum deposits in 345-352
tin deposits in 99-102
work in 30
INDEX.
449
Page.
Tin, deposits of, Alaska 92-93
deposits of, Texas 20,99-102
publications concerning, list of 104
Toms Creek, Tennessee, phosphate de-
posits on 418
Tonopah mining district, Nevada, devel-
opments in 82
geology of -- 82-85
location of 81
ore deposits of 85-87
topography of 82
work in 27,81-87
Trinity group, Arkansas, asphalt deposits
of 353-355
Trumbull, Conn., report on tungsten
mine at 20
Tully claim, Pearl,Colo.,copperdepositsat 165
Tundra placers, Alaska, work on 45
Tungsten, deposits of, Connecticut 98
deposits of, Nevada 103
publications concerning, list of 104
Tungsten minerals in Connecticut, paper
on, notice of 20
U.
Ulrich, E. O., paper by 203-210
work done by 29,30
Utah, bituminous deposits in 302
coal fields in, area and production of. 258
copper deposits in.. 105-122
work in 31-40
V.
Van Hise, C. R., paper by, on ore deposi-
tion, title and notice of 18
work done by 30
Van Hise, C. R., and Bain, H. F., paper
by, on lead and zinc deposits,
title and notice of 20
Vaughan, T. W., cited 263
paper by 392-399
Velpen, Ind. , coal beds near 287-288
Vermilion district, Minnesota, iron ores in 249
Vermont, work in 29
Virgilina copper region (Virginia-North
Carolina), ores in 183-184
Virginia, coal fields in, area and produc-
tion of.. 257, 258
copper deposits in 183-184
gypsum deposits of 406-416
salt deposits of 406-416
workin 30
W.
Warner, A. J., aid by... 61
Warren mining district, Arizona, copper
deposits in... 149-157
development of 152-1 53
geography of 149
geology of 149-152
ores of 153-156
production of 153
Warrior General mine, Washington, op-
erations at 79
Page.
Washington, coal fields in, area and pro-
duction of 258
gold mining in... 76-80
ore deposits in 22
Washington Creek, Alaska, coal beds on. 277
Weed, W. H., paper by, on gold and silver
veins, title and notice of 18
papers by 88-89, 99-102, 170-185
■ work done by 20.22,26-27,30
Weed, W. H., and Barrell, Joseph, paper
by, title and notice of 21
Weeks, F.D., paper by 103
Wells and Penfield, cited 94
West Virginia, coal fields in, area and
production of 258
gr ahamite deposits in. 301
slate bedsin 361-364
White,I. C, cited 336
Whitham, Ga. , fuller's earth beds near . . . 393
Whites Creek, Tennessee, phosphate de-
posits on 424-425
Wilkens and Nitze, cited 57
Willemite, deposits of, New Jersey 214
Williams coal mine, Yukon River, Alaska,
conditions at 281-282
Williams Creek, Washington, gold de-
posits on 76-77
Williams, W. E., acknowledgments to... 278
Willis, Bailey, work done by 30
Wilsdorfs Branch, Tennessee, phosphate
deposits on 419,420
Wolff, J. E.. paper by 214-217
Wolverine claims, Pearl, Colo., copper de-
posits at 166
Woodchopper Creek, Alaska, gold mining
on 48
Woodworth, J. B., cited 266
Wool, mineral, manufacture of, from
iron slag 227-228
Wurtzilite, features of 298-299
Wyoming, coal fields in, area and produc-
tion of 258
copper deposits in 158-162
platinum in copper ores in 94-97
work in 28
Yeates, W. S., cited 57
York, Alaska, tin deposits at 92-93
Ysabellita mines, Cuba, manganese de-
posits at 253-255
Yukon Basin, Alaska, coal resources of 276-283
gold mining in 46-48
Z.
Zinc, deposits of, Arkansas 26,187-196
deposits of, Kansas .' 197-204
Kentucky 205-213
Missouri 2:'.,197-204
New Jersey 214-217
Ozark region, report made on 20
Utah 115,121-122
work on.... 26,30
publications concerning, list of 218
Bull. 213—03-
o
PUBLICATIONS OF UNITED STATES GEOLOGICAL SURVEY.
[Bulletin No. 213.]
The serial publications of the United States Geological Survey consist of (1)
Annual Reports. (2) Monographs. (3) Professional Papers, (4) Bulletins, (5)
Mineral Resources, (6) Water-Supply and Irrigation Papers, (7) Topographic
Atlas of the United States— folios and separate sheets thereof, (8) Geologic Atlas
of the United States — folios thereof. The classes numbered 2,7, and 8 are sold at
cost of publication; the others are distributed free. A circular giving complete
lists may be had on application.
The Bulletins, Professional Papers, and Water-Supply Papers treat of a variety
of subjects, and the total number issued is large. They have therefore been classi-
fied into the following series: A, Economic geology; B, Descriptive geology; C,
Systematic geology and paleontology: D, Petrography and mineralogy; E, Chem-
istry and physics; F, Geography; G, Miscellaneous: H, Forestry; I, Irrigation;
J, Water storage; K, Pumping water; L, Quality of water; M, General hydro-
graphic investigations; N, Water power: O, Underground waters; P, Hydro-
graphic progress reports. This bulletin is the twenty-fourth in Series A, the
complete list of which follows. (B = Bulletin, PP = Professional Paper.)
SERIES A, ECONOMIC GEOLOGY.
B 21. Lignites of Great Sioux Reservation: Report on region between Grand and Moreau rivers,
Dakota, by Bailey Willis. 1885. 16 pp.. 5 pis.
B 46. Nature and origin of deposits of phosphate of lime, by R. A. F. Penrose, jr., with intro-
duction by N. S. Shaler. 1888. 143 pp.
B 65. Stratigraphy of the bituminous coal field of Pennsylvania, Ohio, and West Virginia, by
Israel C. White. 1891. 212 pp., 11 pis. (Exhausted.)
B 111. Geology of Big Stone Gap coal field of Virginia and Kentucky, by Marius R. Campbell .
1893. 106 pp., 6 pis.
B 132. The disseminated lead ores of southeastern Missouri, by Arthur Winslow. 1896. 31 pp.
B 138. Artesian-well prospects in Atlantic Coastal Plain region, bv N. H. Darton. 1896. 22* pp.,
19 pis.
B 139. Geology of Castle Mountain mining district, Montana, by W. H. Weed and L. V. Pirsson.
1896. 164 pp., 17 pis.
B 143. Bibliography of clays and the ceramic arts, by John C. Branner. 1896. 114 pp.
B 164. Reconnaissance on the Rio Grande coal fields of Texas, by T. W. Vaughan, including a report
on igneous rocks from the San Carlos coal field, by E. C. E. Lord. 1900. 100 pp., 11 pis.
B 178. El Paso tin deposits, by Walter Harvey Weed. 1901. 15 pp., 1 pi.
B 180. Occurrence and distribution of corundum in United States, by J.H. Pratt. 1901. 98pp.,
14 pis.
.B 182. A report on the economic geology of the Silverton quadrangle, Colorado, by F. L. Ran-
some. 1901. 266 pp., 16 pis.
B 184. Oil and gas fields of the western Interior and northern Texas Coal Measures and of the
Upper Cretaceous and Tertiary of the western Gulf coast, by G. I. Adams. 1901. 64 pp.,
10 pis.
B 193. The geological relations and distribution of platinum and associated metals, by J. F. Kemp.
1902. 95 pp., 6 pis.
B 198. The Berea grit oil sand in the Cadiz quadrangle, Ohio, by W. T. Griswold. 1902. 43 pp., 1 pi.
PP 1. Preliminary report on the Ketchikan mining district, Alaska, with an introductory sketch
of the geology of southeastern Alaska, by Alfred Hulse Brooks. 1902. 120 pp., 2 pis.
B 200. Reconnaissance of the borax deposits of Death Valley and Mohave Desert, by M. R.
Campbell. 1902. 23 pp., 1 pi.
B 202. Tests for gold and sliver in shales from western Kansas, by Waldemar Lindgren. 1902.
21pp.
PP 2. Reconnaissance of the northwestern portion of Seward Peninsula. Alaska, by A . J. Collier.
1902. 70 pp., 11 pis.
PP 10. Reconnaissance from Fort Hamlin to Kotzebue Sound, Alaska, by way of Dall, Kanuti,
Allen, and Kowak rivers, by W. C. Mendenhall. 1902. 68 pp., 10 pis.
PP 11. Clays of the United States east of the Mississippi River, by Heinrich Ries. 1903. 298 pp.,
9 pis.
PP 12. Geology of the Globe copper district. Arizona, by F. L. Ransome. 1903. 168 pp.. 27 pis.
B212. Oil fields of the Texas-Louisiana Gulf Coastal Plain, by C. W. Hayes and William Ken-
nedy. 1903. —pp., 11 pis.
B 213. Contributions to economic geology, 1902; S. F. Emmons, C. W. Hayes, geologists in charge.
19013. 449 pp.
LIBRARY CATALOGUE SLIPS.
[Mount each slip upon a separate card, placing the subject at the
top of the second slip. The name of the series should not be
repeated on the series card, but add the additional numbers, as
received, to the first entry.]
U. S. Geological survey.
. . . Contributions to economic geology, 1902.
S. F. Emmons [and] C. W. Hayes geologists in
charge. Washington, Gov't print, off., 1903.
449, III p. 23cm. (Bulletin no. 213.)
Contains contributions by various members of the survey. A
list of previous publications by the survey on each subject is given.
Subject series A, Economic geology, 24.
U. S. Geological survey.
. . . Contributions to economic geology, 1902.
S. F. Emmons [and] C. W. Hayes geologists in
charge. Washington, Gov't print, off., 1903.
449, III p. 23cm. (Bulletin no. 213.)
Contains contributions by various members of the survey. A
list of previous publications by the survey on each subject is given.
Subject series A, Economic geology, 24.
U. S. Geological survey.
Bulletins,
no. 213. Contributions to economic geology, 1902.
1903.
U. S. Dept. of the Interior.
see also
U. S. Geological survey.
in
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