Bulletin No. 219 iM / A| Economic Geology, 27 

) Descriptive Geology, 33

DEPARTMENT OF THE INTERIOR

UNITED STATES GEOLOGICAL SURVEY

CHARLES D. WALCOTT, DIRECTOR

THE

(PEELIMINAET EEPOET)

BY

J. E.

WASHINGTON

GOVERNMENT PRINTING OFFICE

1903
' o - a . s. GL E 

439

Reprinted in January, 1904.
CONTENTS.

Page.

Location, climate, and population .-__._.---.__-__._-_.__.._..._______.._._ 7

Discovery and development'___._...__.__._-._.__.____._.____,.._...______ 7

Topography ___...___________.__..__.__.._..___._._.______._.__........... 9

General geological history..........-......-...--..--....-.--..-.-...-.... 9

Pre-Tertiary formations._-----..._-----._..---.-_.--_-..._..,...-.--- 9

Early andesite eruption .................... -------------.___._---____ 9

Later andesite eruption ............................................... 10

Rhyolite and dacite eruptions --..-_----._.__----__..----.___----.___. 10

Lake sediments _.-----.-.-_----_-.-----..---__-'----.-----..------_.--. 10

Eruption of basalt and intrusion of later dacites and rhyolites --------- 10

Faulting of the region ......-........--...------....-.....-...-.-.... 11

Recent erosion....................................................... 12

Sequence of formations and events..-.-.--..-.-..---.---.----_---.... ' 12

Description of the rocks of the region..................................... 12

Distribution and characteristics of the early andesite.................. 12

Distribution and characteristics of the later andesite.................. 13

Distribution and characteristics of the rhyolites....................... 14

Distribution and characteristics of the dacites ......................... 14

Periods and nature of mineralization ------.--------.-...-----.-..---..-.. 15

Mineralization subsequent to the early andesite intrusion.............. 15

Mineralization subsequent to the early rhyolite intrusion.............. 16

Mineralization subsequent to the later rhyolite intrusion .............. 16

Mineralization subsequent to the dacite intrusions .................... 17

Resume ..--.-.----.--..-..--....-..---...---.-----.-.--.---.-..-.--. 17

Vein groups of the' early andesite mineralization..--...---.--...-..--..... 18

Occurrence of ores in the veins---.-......-.....----.......--........-.... 21

Physical character_._________._.__..__._.__._______._._..__._....____ 21

Primary ores .......-................._...-.---..-....-..--...-...... 23

Secondary sulphides ................................................1 23

Oxidized ores ---.-..---.-.-..----.-.----...---.--....------.-..----.. 23

Ore shoots..-......---...;-.--..----.--..-..-...----.-.....-.--....... 25

Application of geological principles ...................................... 25

Index ................................................................... 29

ILLUSTRATIONS.

Page. 

PLATE I. Geologic map of Tonopah mining district........................ 7

FIG. 1. Plan of portion of Mizpahvein.. _________.......................... 18

2. Map showing outcropping veins at Tonopah........................ 19

3. Detailed vertical section of one of minor Valley View veins........ 22

4. Ideal cross section of Tonopah rocks .............................. 26

U. S. GEOLOGICAL SURVEY

BULLETIN NO. 219 PL. I

JEarly andesite Later andesite Early daoite Dacite-breccla Khyolite-breccia Tuffs 

(lode porphyry) pro.bably intrusive formation flows and dikes. (Jake beds)

v Heayy Wack lines are faults. 

Scale

Basalt White rhyolite Later dacite

( volcanic necks ( volcanic necks

and dikes) and. dikes)

Imile

dontour interval 100 feet 

Datum is mean sea level

GEOLOGIC MAP 'OF TONOPAH MINING DISTRICT.
By J. E. SPURR.

LOCATION, CLIMATE, AND POPULATION.

Tonopah is situated in Nye County, Nev., near the Esraeralda County 

line. It lies south of Belmont, and about GO miles cast of Sodaville, 

which is 011 the Carson and Colorado Railroad. The camp is reached 

.by semidaily stage from the latter point.

The climate is arid, with rare rains and occasional snows. The 

present water supply is pumped from wells in a water zone some 4 

miles north of the town.

At the present writing the camp has an estimated population of 

5,000. It has electric lights, waterworks, two newspapers, and has 

attracted enterprising men from all parts of the country.

DISCOVERY AND DEVELOPMENT.

Tonopah was discovered in 1900 by J. L. Butler, who was on a prospecting trip. He gave his samples to Mr. T. L. Oddie, of Belmont, 

who had them assayed for him. These samples showed values of from 

$50 to $600 to the ton. Mr. Butler gave T. L. Oddie, W. Brougher, 

and several others interests in the original eight claims which he 

located, now the property of the Tonopah Mining Company.

In doing the location work 2 tons of ore was sorted out and shipped 

to Selby's Smelting Company. This netted about $600, and from that 

time the property has paid for its own development.

In December, 1900, a few leases were let, and in the spring of 1901 

over a hundred more. Before the end of 1901 the lessees are said to 

have extracted ore to the value of about $4,000,000. In January, 1902, 

the leases having expired, the Tonopah Mining Company commenced 

development work, in which it is still engaged.

a The writer has spent about five months in field work at Tonopah and four months at Washington studying material collected at Tonopah. A satisfactory final report on the district calls 

for more detailed office study, microscopic examination of thin sections, chemical investigation, 

etc., which will now be carried on, and the completed report issued as soon as possible. Since, 

however, there is an urgent call by the mining public for some immediate information concerning the region, the Director has authorized the writer to issue a preliminary report containing 

an outline of the results to date. " . . ...

7
8 OEE DEPOSITS OF TONOPAH, NEVADA. [BULL. 219."

Following is a table of the weight and value of the ore shipped, ' {.. 

taken from smelter returns: a

Weight and value of ore shipped to April 1, 1903. ..t'

Year.

1901. ........ .-.------.-.-..-----..-.--

1902... ._____:_._..._._..._. .A. ........

1903 (to April 1). .......................

Total -...-..--...-_.-..---..--.--

Weight.

Pounds.

5, 067, 852

22, 886, 355

3,481,443

31,385,650

Gold.

Ounces. 

9, 780. 95

27, 003. 84

4, 212. 96

40, 997. 75

Silver.

Ounces. 

623, 487. 83

2, 408, 946. 60

399, 186. 30

3,431,620.73

Total value, $2,662,401.25.6 . *, 

There are now c on the dump close to 25,000 tons of ore, of an aver- *

age value of $50 per ton. } 

Subsequently ledges were cut in a number of different localities, " 

such as the Montana Tonopah, Mizpah Extension, California Tonopah,; 

West End, etc. Some of these are low grade, while some show high, 

values. All are in the development stage.

Besides the Mizpah the only mine in the Tonopah district proper \ 

which has actually made shipments of importance, so far as thef 

writer is aware, is the Montana Tonopah, where ore was discovered 1 

in depth by prospecting under the later andesite capping after the.; 

discovery and earlier development of the Mizpah vein. The ship-* 

.ments^ of the Montana Tonopah to and including July 15 of thej

present year (1903) are as follows: ;

i*

Shipments from the Montana Tonopah mine to July 15,1903. 

Shipment.

First shipment, May 5: 

First-class ore -..........-..........._......._..

Second-class ore. . ...... ...................

Second shipment, third-class ore for mill test. ...........

July 15. _-..------.----..........._____..__._.______.__.

Total ............................................

Pounds.

29, 128

23, 331

21, 200

r 29,019

I 15,664

118, 342

.! 

Total value. 

i 

$6, 596. 8*

2, 472. 7t

. 749. 2i

4, 881. 8 J

715. c;

14, 915. 8', ' t iShipments have been made by both companies since these data wer 

collected. ^

a For this tabla and the preceding information the writer is indebted to Mr. T. L. Oddie, manager, at Tonopah, of the Tonopah Mining Company. ', 

b Estimated by the writer. ! 

c May, 1903. 

d Courtesy of Mr. C. E. Knox, president Montana Tonopah Mining Company. v
SPUKB.] TOPOGEAPHY AND GEOLOGICAL -HISTOEY. 9

The values in the ores are entirely gold and silver. The proportion of gold to silver is usually remarkably uniform, and is the same 

in both the oxidized and the sulphide ores, namely: The gold is to 

the silver, by weight, as 1:90 or 1:100, making the values about twosevenths gold and five-sevenths silver. In some of the excessively 

rich ores the proportion of gold becomes greater, occasionally making 

up half of the total value.

TOPOGRAPHY.

That the mountain range in which Tonopah is situated is of volcanic 

origin is shown by its topography. It consists of a series of eroded 

mesas and detached or connected hills. These mesas and hills are 

irregularly distributed, with no definite valley systems between. They 

are separated by patches of sloping or rolling country, largely covered 

with "wash," or debris worn from the hills. The mesas are the remnants of volcanic flows; the isolated or connected irregular hills are 

denuded volcanic necks.

An excellent topographic map of the country immediately around 

Tonopah, on the scale of 800 feet to an inch, has been made by Mr. 

W. J. Peters, of the United States Geological Survey. On this it is 

seen that the general elevation of the slight valley-like depression in 

which the town of Tonopah lies is about 6,000 feet above sea level, 

while the top of Butler Mountain, which is the highest mountain near 

the town, is 7,160 feet.

GENERAL GEOLOGICAL HISTORY.

Pre- Tertiary formation. In the immediate vicinity of Tonopah the 

rocks are all Tertiary volcanics or sedimentary tuffs belonging to the 

volcanic period, and composed partly of ash and partly of silt derived 

from the erosion of the lavas. Eight or nine miles south of the camp, 

however, there is limestone, very likely of Cambrian or Silurian age, and 

in this granitic rock is intrusive. Limestones and granites occur also 

several miles north of Tonopah, and at intervals between there and 

Belmont. At Belmont the limestone, into which granite is intrusive, 

is known to be Silurian.

At Tonopah itself occasional limestone fragments and more abundant fragments of a fine, even-grained pegmatite occur in the volcanic 

breccias. They are blocks which were hurled out from the volcanoes 

at the time of their eruption. Thus it is shown that at an uncertain 

depth below the present surface the ascending lavas broke through 

rocks of this character.

Early andesite erwption. The oldest rock outcropping in the immediate vicinity of the camp is a hornblende-andesite, or, rather, was 

such, for no fresh portions ha.ve been found and the rock has been 

altered so as to acquire an aspect in general very different from its 

original one.
10 OEE DEPOSITS OF TONOPAH, NEVADA. [BULL. 219.

Subsequent to the eruption of this rock fractures were formed in 

it, and these became the channels for circulating solutions, probably 

ascending hot waters, closely connected with the volcanism. The 

waters were remarkable for intensity of action. The rocks which 

they traversed have been chemically transformed, the chief process 

being silicification, so that they are now found more or less completely 

altered to quartz and sericite (fine muscovite). Along fracture zones 

the rock has been replaced almost entirely by quartz carrying .silver 

and gold, and these constitute the veins lay which Tonopah is known. 

Some parts of the hornblende-andesite, on the other hand, show 

chiefly calcite-and chlorite, with pyrite, as alteration products; but 

such phases have not yet proved to lie immediately adjacent to 

important veins, and, as a rule, do not seem to be indicative of the 

proximity of the best class of ore.

Later andesite eruption. There is evidence that these events were 

followed by a considerable period of erosion, long enough to bring the 

veins to the surface. Then another eruption of andesite occurred. 

This later andesite, which was abundant in amount, differed from 

the earlier andesite in containing, as dark minerals, pyroxene and 

biotite rather than hornblende, and it also differed in some structural 

and textural points. It is probable that this andesite came up through 

the hornblende-andesite in places, and also flowed over it, completely 

covering it and its contained veins.

Rhyolite and dacite eruptions. Following probably another period 

of erosion and volcanic rest, eruption was vigorously renewed and 

there were outbreaks at many closely adjacent points. The lavas 

were rhyolites and siliceous dacites, closely related to one another. 

Some vents emitted one, some the other rock. This period of volcanism was long and a number of different lava flows of dacite and rhyolite alternated or mingled. The eruptions were often explosive, as is 

shown by the considerable quantity of pumiceous and fragniental 

material in the volcanic breccias of this period.

Lake sediments. During this volcanic epoch a large fresh-water 

lake formed, of unknown, but probably great extent. In it were 

deposited white, finely stratified ash and tuff, and some beds are 

entirely made up of late Tertiary infusoria. In places the sediments 

of this lake, exposed near Tonopah, are several hundred feet thick.

It is probable that this lake was partly filled by sediments and then 

drained by an uplift. Near the top of Siebert Mountain (a white tuff 

mountain southwest of Mount Brougher) there is what appears to be 

a river channel belonging to this post-elevation epoch, containing 

rounded waterworn pebbles of rocks such as now outcrop to the north 

and east of Tonopah, and fragments of silicified wood, showing the 

presence of vegetation at that time. This uplift may be ascribed to 

volcanism, for it was soon followed by renewed outbursts of lava.

Eruption of basalt and intrusion of later dacites and rhyolites. 

Above the tuffs on Siebert Mountain is a thin sheet of slaggy basaltic
SPUKR.] GENERAL GEOLOGICAL HISTOEY. 11

rock, the first of the upwellings of the next period of volcanic activity. 

Soon afterwards great columns of dacite and rhyolite made their way 

to the surface. The eruptions from these vents must have been chiefly 

explosive, and the products light and scanty and easily swept away, 

for no trace of them has been found in the immediate vicinity of 

Tonopah. The volcanic necks, however, have been laid bare by erosion, and on account of their superior hardness to the tuffs and breccias, in which they were intruded, now stand up as low detached 

mountains. Brougher Mountain, B utler Mountain, Siebert Mountain, 

and Golden Mountain are all dacite nocks of this period, while a group 

of rhyolite eminences, consisting of Oddie and Ararat mountains and 

Rushton Hill, represent necks of very nearly the same period as the 

dacite.

Faulting of the region. At about this period occurred an event of 

great scientific and economic interest the faulting. A considerable 

number of important and complicated faults have been found in the 

region. Their age, as denoted by their relations to the different formations, seems nearly uniform. All the rocks up to and including 

the stratified tuffs have been displaced by the faulting, and on Siebert 

Mountain the thin sheet of basaltic rock overlying the tuff: has been 

faulted with it. But these, faults invariably stop at the contact of 

the dacite necks, which are not affected, and the same is probably, 

though less certainly, true of the rhyolite necks above noted. . Indeed, 

the dacite certainly (and the rhyolite less certainly) has been intruded 

as dikes along the faults.

The geological map (PL I) reveals some important points. It shows 

that the area of observed complicated faulting is in general coextensive with the region of late dacite intrusion. This region, which 

occupies the southeastern portion of the district, is downsunken in 

comparison with the unfaulted or little-faulted region on the northwest. Near the dacite necks the observed faults are rather more 

numerous than elsewhere, and in many instances it may be established that the blocks adjacent to the dacite have been downsunken 

in reference to blocks farther away. From these intrusive necks the 

faults run in a roughly radiating fashion and seem to follow no regular system of trend. Detailed study of the contact phenomena of the 

dacite shows .that the minute faults in the tuffs at these points generally have their downthrown side next the dacite. From these facts 

the following conclusions have been reached. The faulting was 

chiefly initiated by the intrusion of the massive dacite necks (the 

rhyolite necks were probably not so bulky). After this intrusion 

and subsequent eruption there was a collapse and a sinking at the 

various vents. The still liquid lava sank, dragging downward with 

it the adjacent blocks of the intruded rOck, accentuating the faults, 

and causing the described phenomena of downfaulting in the vicinity 

of the dacite. This sinking of volcanic centers after eruption has 

been well established by students of volcanism.
12 ORE DEPOSITS OF TONOPAH, NEVADA. [BULL. 219. ~

The economic interest in this faulting lies largely in the circumstance that the veins in the early andesite have been cut and displaced 

thereby.

Recent erosion. To complete the geological history, we have to conceive of the considerable period of erosion which stripped from the 

surface a great thickness of volcanic material, leaving the resistant 

volcanic necks standing out as hills, and laying bare the present surface. Certain blocks of limited extent had been raised by the faulting above the level of the rest, and here the surface of erosion reached 

the early andesite and uncovered the rich veins contained in it; and 

it is the discovery of these veins which has made the subject of the 

geology of the still covered region of-such lively interest to miners.

Sequence of formations and events. The following, then, is the 

sequence of events as deciphered for the vicinity of Tonopah:

i 

Sequence of formations and events in the vicinity of Tonopah.

Early andesite.

Fracturing.

Vein formation. (Primary minerals, quartz,.valencianite, stephanite, pyrite,

chalcopyrite?) Values good; gold and silver, silver predominant. 

Erosion. 

Later andesite. 

Probable erosion. 

Dacite.

Dacite breccia.

Rhyolite breccias, flows, and dikes, intermingled with slightly stratified or interstratified pumiceous or tuffaceous fragmental material.

Vein formation. (Primary minerals, quartz, pyrite.) Values relatively low;

gold and silver, gold apt to predominate. 

Erosion.

Tuffs, with an occasional thin rhyolite flow. 

Elevation of tuffs. 

Tilting. 

Basalt.

Chief faulting. (Affects everything preceding.) 

Rhyolite (white) intrusion (probably Ararat, Oddie, Rushton hills).

Vein formation. Primary minerals, quartz, chalcedony, calcite, siderite,

pyrite.) Values low; gold and silver, gold apt to predominate. 

Erosion. 

Dacite intrusion (Butler, Brougher, Golden, Siebert mountains).

Mineralization (chalcedony, manganese). Values slight to insignificant.

Mud veins. 

Erosion. 

Glassy rhyolite flow (slopes of Oddie and Brougher).

DESCRIPTION OF THE BOCKS OF THE REGION.

Distribution and characteristics of the early andesite. This was 

originally a hornblende-andesite, containing probably some biotite 

and pyroxene. In the immediate vicinity of Tonopah it outcrops 

only, so far as observed, on Mizpah Hill and Gold Hill; but it has been
SPUR*.] DESCRIPTION OF THE BOOKS. 13

discovered under younger rocks in a number of different mines, such 

as the Montana Tonopah, the North Star, the Ohio Tonopah, the 

California Tonopah, the "Wandering Boy, part of the Fraction at 

least, and probably the West End and MacNamara, the Midway, etc. 

Nowhere is it in even an approximately fresh state, but, as before 

noted, it has altered largely to calcite and chlorite, and (more commonly in the vicinity of the veins) to quartz and sericite. In the 

former condition it has a fairly deep-green or blue color, while in the 

latter phases it is lighter green or blue, and very often nearly white, 

or assumes, near the surface and along faults or fractures, a pale 

yellowish, brownish, or reddish color. This common quartz-sericite 

type has the appearance of rhyolite rather than of anything else, and 

does not at all resemble andesite, while the calcite-chlorite phase has 

more nearly the rightful aspect of a highly altered andesite.

It is difficult always to distinguish this early andesite with certainty 

on account of its many different phases. It is most likely to be confounded with the later andesite on one hand and with certain types 

of rhyolite on the other. The main points of difference will be outlined shortly.

Distribution and characteristics of the later andesite. The later 

andesite outcrops over a considerable region in the northern part 

of the district. The upper portions, and in some cases the whole, of 

the following shafts are in it: Montana Tonopah, North Star, Midway, Golden Anchor, Little Tonopah, Boston Tonopah, Halifax, etc. 

It varies greatly in state of preservation, being frequently found 

nearly fresh, and again highly decomposed. In its fresher phases 

it is a dark-colored, hard rock, with large crystals of pyroxene, feldspar, and biotite. It has usually been more or less altered, and 

as secondary minerals calcite, chlorite, serpentine, etc., have been 

formed, giving the rock a dark-green color. Frequently, also, the 

altered rock has a deep-blue color. Near the surface the red of the 

oxidized iron combines with these colors to produce a characteristic 

rich purple. In some places the rock has been thoroughly altered to 

calcite, chlorite, and pyrite, with other secondary minerals, and again 

has been so completely leached as to be soft and white.

In these highly altered phases the later andesite becomes with great 

difficulty distinguishable from the early andesite, and where it is fine 

grained the resemblance may become almost exact.

For the distinction of the two rocks in general it may be noted that 

the early andesite is characteristically finer grained than the later 

andesite, and that in the former the feldspar crystals, are slimmer and 

rectangular, while in the latter they are stouter and often of complex 

shape. In some of the hornblende-andesite (though not generally) the 

long dark crystals of altered hornblende may be distinguished, while 

in the later andesite the crystals of biotite are usually plainly visible, 

even in the considerably altered phases. The characteristic later 

andesite has a coarse, mottled appearance, and even when highly
14 OEE DEPOSITS OF TONOPAH, NEVADA. [BULL. 219.

altered and bleached it has a dull clayey luster, which is rarely seen 

in the early andesite. Rocks which are highly siliceous from alteration are apt to belong to the early rather than the late andesite.

Distribution and characteristics of the rhyolites. There have been 

several different rhyolite flows and intrusions, some before, some 

mainly subsequent to the faultings; and the rocks have a variety of 

appearances which defies any description in common. The lava of 

Oddie, Rushton, and Ararat hills is a characteristic siliceous white 

rhyolite. The Rescue shaft is mainly in this rock, and two long 

tunnnels, the North Star and the GL & H., have been driven in it into 

Mount Oddie.

Besides this, however, there is a formation, of fine-grained gray or 

red, largely glassy rhyolite, which covers a still larger area. A large 

body of it occupies the northern portions of the district, where it is 

intrusive, with a sinuous contact, into the later andesite. It continues 

from here, along the western edge of the district, to the vicinity of 

the Ohio Tonopah, and occupies a considerable part of the basin 

inclosed between Butler, Brougher, and Siebert mountains. The formation here occurs as complicated dikes cutting the dacite-breccia 

formation, and as sheets underlying the tuff, or, to a less extent, intercalated in the tuff. In the rest of the district it is practically absent. 

It is in general between the dacite breccia and the stratified tuff in 

point of age, is older than the faults, and is therefore displaced by 

the fault movements. In the northern portion of the district a number of shafts are located on or near the contact of this rhyolite and 

the later andesite. Among these may be mentioned the King Tonopah, Belle of Tonopah, Miriam, Silvertop, Little Tonopah, etc. In 

the western portion the Ohio Tonopah and the New York Tonopah 

each encountered a considerable quantity of this rhyolite mixed with 

dacite breccia, while the Fraction extension is entirely in this rock, 

after having passed through the overlying tuff.

This finer grained gray or red rhyolite has many different aspects. 

Fine brecciation, with bright red, gray, and white colors, is frequent; 

in other cases it is dense and characterless. The best test of it is the 

detection of the small quartz crystals that dot the glassy groundmass, 

which distinguishes the ro.ck satisfactorily from the andesites. Sometimes, however, these quartz crystals maybe rare and small. Near 

the contacts of the rhyolite (intrusive into the earlier rocks) there 

has also frequently been alteration silicification, the formation of 

pyrite, etc. and then the rock may become almost identical in 

appearance with the early andesite which has been similarly altered. 

The best method for distinguishing the rhyolite from andesite in this 

case is the tracing of the connection with the less-altered rhyolite 

farther away from the contact. . Distribution and characteristics of the dacites. The bold knob 

north of Butler Mountain, known as Heller Butte, is made up of what
SPUBB.] PERIODS AND NATURE OF MINERALIZATION. 15

is regarded as probably the oldest dacite exposed at the surface. It 

is a compact, relatively coarse-grained rock, finely brecciated, and 

carrying included fragments of older rocks, notably the later andesite. 

It is surrounded and probably overlain by the softer dacite-breccia 

formation. The Tonopah City shaft after passing through the dacite 

breccia has continued in solid Heller dacite to a total depth of over 

500 feet. East of Butler Mountain, on the edge of the district, 

another strip of this dacite is exposed, also surrounded by the dacite 

breccia. It is regarded as probably intrusive.

The dacite-breccia formation, on the other hand, is essentially a sur- 

'face formation, and not intrusive. It consists of flows of often very 

pumiceous and friable dacite, dacitic mud flows, and some rudely lay-

-y-^, ered or even stratified fragmental material. In places it is very thick.

/- It is exposed over a large fraction of the southern portion of the district, around Butler, Brougher, and Siebert mountains. The Ohio

Tonopah and the New York Tonopah shafts passed through considerable thicknesses of this formation, and the Fraction No. 3 is entirely 

in it. The Fraction Nos. 1 and 2, and "Wandering Boy, and the West 

End, passed through this formation at the surface and reached the 

underlying formations.

The later intrusive dacite, which makes up Butler, Brougher, and 

Golden mountains and the central portion of Siebert Mountain, has 

usually a characteristic appearance. It is darker than the rhyolite of 

Mount Oddie, has a slight purplish tinge, and contains more crystals 

(of feldspar, quartz, and mica) embedded in the glassy groundmass. 

The Big Tono shaft, at the east foot of Mount Brougher, starting at 

the outward-pitching contact of this rock and the intruded dacitebreccia formation, goes down several hundred feet in the former. 

The Molly, starting near the dacite contact on Golden Mountain, 

passed through several hundred feet of this rock, then through the 

inward-pitching contact to a slight thickness of loose material belonging to the dacite-breccia formation, and so into the later andesite.

PERIODS AND NATURE OF MINERALIZATION.

Mineralization subsequent to the early andesite intrusion. The most 

important veins of the Tonopah district, and all those that have been 

proved to be of immediate economic importance, occur in the early 

andesite, and do not extend into the overlying rocks. Hence, when 

the early andesite is not exposed at the surface, the later rocks form 

a capping to the veins, and this capping must be passed through 

before anything can be learned of the presence or the nature of the 

veins beneath. This circumstance shows pretty plainly that the vein 

deposition took place before the eruption of the later andesite, and 

immediately after that of the early andesite (for the period of erosion 

between the two andesites seems to have exposed the-veins at the surface, showing that they were formed before this period, or early in it).
16 OEE DEPOSITS OF TONOPAH, NEVADA. [BULL. 219.

Indeed, there is every evidence that the veins were formed by ascending hot waters succeeding and connected with the early andesite intrusion, and that these waters had apparently become inactive by the 

time of the later andesites.

The mineralization at this period was extraordinarily active, as the 

profound alteration of the early andesite testifies. Among the known 

veins formed at this period those of the Valley View, Mizpah, and 

Montana Tonopah groups are the most important, though certainly 

there are others which have not yet been discovered. These veins 

carry gold and silver, in the proportion of about 1 part of gold to 

100 of silver, by weight. They are unusually free from base metals 

no lead, arsenic, etc., has been detected. In some places there is a 

very little copper, in others none. The gangue is quartz, with frequently a mineral which is a variety of orthoclase feldspar (valencianite). The sulphide ores, so far as developed, show primary stephanite, with probably some polybasite, scant pyrite, and comparatively 

rare chalcopyrite. Secondary sulphides coating the cracks in these 

ores are ruby silver, argentite, and probably pyrite and chalcopyrite. 

The oxidized ores show abundant silver chloride, with occasional 

bromides, etc., and sometimes free gold.

Mineralization subsequent to the early rhyolite intrusion. Along 

the borders of the gray or red glassy rhyolite intrusions, especially in 

the northern portion of the district, there has been, as before noted, 

considerable alteration and mineralization, which must be attributed 

to a cause similar to that which produced the veins in the early andesite namely, the action of hot ascending waters immediately succeeding and genetically connected with the rhyolite intrusion. This 

alteration is in the form of silicification and the formation of pyrite, 

and has acted on the rhyolite as much as the intruded rock. Quartz 

veins have been formed, in the majority of cases relatively small.

These veins contain precious metals, but usually very irregularly 

distributed. High assays, especially on the surface, may even be 

obtained, but it is likely that some of these are the result of the wellknown process of increase of values at the surface during oxidation. 

Specimens of the veins have a general resemblance to those of veins 

of the early andesite, and show pyrite, often finely disseminated in a 

quartz gangue. Some of these veins have been found to be of considerable size; therefore it may often be difficult to distinguish them 

from the andesitic veins without study of the rock in which they lie. 

Chemically they appear to be characterized, so far as yet developed, 

by very low average values and by the frequent but not regular 

preponderance of the gold values over those of silver.

Mineralization subsequent to the later rhyolite intrusion. It has 

been described how the white rhyolite of Oddie, Rushton, and Ararat 

hills is probably later than the dense, usually gray rhyolites referred 

to above. For example, the top of Ararat seems to be a plug or neck
SPUBK.] PERIODS AND NATURE OF MINERALIZATION. 17

of white rhyolite forced up into the earlier gray rhyolite. This later 

white rhyolite shows near its contacts, and to a less extent away from 

these, in itself or in the intruded rock, veins which are ascribed to 

causes similar to those which probably brought about the preceding mineralizations namely, ascending heated waters following the 

lava intrusion, genetically connected with it, and, like the previous 

similar processes, dying out after the lapse of some time. These 

veins, which are in places very large, are of calcite, siderite or ferriferous calcite, chalcedony, etc. They contain some pyrite and sometimes give low values in the precious metals, gold preponderating.

Mineralization phenomena may also be observed in some places near 

the contact of the Oddie Mountain rhyolite, where there is silicification and the formation of pyrite, with quartz veins of various sizes, 

sometimes containing calcite. These veins are generally small, but 

may be large. Galena and chalcopyrite have been exceptionally found

in them. They carry low values in gold and silver, the gold being 

apt to predominate.

Mineralization subsequent to the dacite intrusions. Finally, the 

contacts of the large dacite necks (Butler, Golden, and other mountains) are accompanied in many places by the deposition of chalcedony, manganese, etc., in cracks and crevices. These are not usually 

in veins, or when so are small and irregular. Considerable values in 

the precious metals have been claimed in some cases, but it is the 

writer's experience that the content of these metals is insignificant.

Resume.- To sum up, no fewer than four periods of hot-spring 

action, accompanied by more or less vein formation and mineralization, have been noted at Tonopah. Each of these periods was consequent upon a lava intrusion, and the mineralization was the result of 

a process which is known to accompany and follow volcanic eruption 

at the present day. In general, the values found in the veins of these 

different periods increase with increasing age. Also, the general phenomena indicate that the younger veins were formed nearer the surface than the older ones. Although ascending hot waters are not 

known .to deposit more than traces of metals at the surface, it is supposed that an important precipitation takes place at some depth; so in 

the case of Tonopah it may be that the later periods of mineralization 

have produced some rich ores, but that erosion has not yet had time 

to expose the level at which they lie, whereas in the case of the oldest 

period this has been accomplished. At Gold Mountain, about 4 miles 

south of Tonopah, veins belonging to the rhyolitic period and having 

the same characteristics as some of these veins at Tonopah contain 

considerable values in gold and silver, while at Tonopah no such 

values have been discovered in this class of veins.

At Tonopah, therefore, the earliest and most important class of 

veins can be found only in the earlier andesite. The rhyolite veins, 

on the other hand, may occur in the rhyelites, as in any of the older 

Bull. 219 03 2
18 OKE DEPOSITS OF TONAPAH, NEVADA. [BULL. 219.

rocks; indeed, they must also occur sometimes in the early andesite 

itself. The mere fact of a vein lying in the early andesite, therefore, 

is not always evidence that it belongs to the early andesite period. 

In some such cases it may be extremely difficult, if not impossible, to 

tell to which period it belongs.

The later andesite is in many cases thoroughly decomposed and 

altered', and there has been extensive formation of pyrite, calcite, 

etc., in it, especially in the regions where the richest veins have been 

found. The nature of this alteration is such as to indicate copious 

percolating waters as the agents, and to suggest that the waters may

have been heated. It is quite possible 

that some of the small sulphide-bearing 

veins, which are frequently found in the 

later andesite, may have been formed 

contemporaneously with this alteration. 

These veins are nonpersistent, and the 

values contained are small. Physically 

they resemble the rhyolitic veins, and as 

they have been iioted chiefly in the general vicinity of rhyolite, which is intrusive into the later andesite, they have 

been classed with the undoubtedly rhyolitic-veins. It is possible, however, that 

a moderate mineralization, similar in 

quantity to that which succeeded the 

rhyolite eruptions, followed that of the 

later andesite.

VEIN GROUPS OF THE EARLY 

ANDESITE MINERALIZATION.

The only productive veins thus far discovered in the Tonopah district proper 

are those of the early andesite period. 

On account of the later volcanic rocks 

which cover the early andesite in most 

of the district, these productive veins 

outcrop only in a very small area, outside of which little is known as 

yet. It is probable, however, as indicated by the great amount of 

alteration in the early andesite, that the vein formation has been 

extensive, and that the veins at present known are only a small portion of those that will eventually be developed.

The veins already discovered all belong to the type of "linked 

veins." Their physical characteristic is that they branch and reunite 

in both a horizontal and a vertical direction (fig. 1). There is generally in each group a main or master vein from which the smaller 

veins branch. These smaller veins again may subdivide and so finally

FIG. 1. Horizontal plan of portion of 

Mizpah vein, as developed on the 250- 

foot level, Mizpah mine, east of the 

Brougher shaft.
SPUKR.] VEIN GROUPS. 19

die out. The main vein and its branches may together be termed a 

"vein group."

Veins probably of the early andesite period have been discovered 

in various mines outside of Mizpah Hill, where the first discoveries 

were made. Among these later developments may be mentioned the 

California Tonopah, the MacNamara, the West End, the Ohio Tonopah, and other workings. But it is only the veins on Mizpah Hill

N

A

North Star Shaft a

9 Tonopah Extension Shaft

a MacNamara Efoaft

Montana Tonopah Shaft"

Tonopah Mining Company 

a Main Shaft

m Went End Shaft

BBraetton No.l Shaft

*Eraction No.8 Shaft S'l

a Wandering Boy Shaft

 Eraotlon No.6 Shaft

 Desert QueenShaft "

a Silver Top Shaft 

n Stono Cabin Shaft

Valley View 

Vein Group

 Gold-Hill Shaft

a Tonopah City Shaft

300 200 100 0

California 

.TonopaU 

" Shaft

FIG. 2. Map showing outcropping veins at Tonopah.

that have been sufficiently developed to give information concerning 

the vein system. On Mizpah Hill there may be recognized at present 

three main groups of veins the Valley View group, the Mizpah group, 

and the Montana Tonopah group. These are all strong and distinct 

(fig. 2).

The Mizpah group lies in the center, between the other two, and was 

the first discovered. The trunk vein of the group is called the " Miz-
20 OEE DEPOSITS OF TONOPAH, NEVADA. [BULL. 219.

pah" vein, and crosses Mi/pah Hill in an east-west direction, showing 

a strong outcrop. This outcrop is cut off both to the east and to the 

west by heavy faults, so that it is adjoined on the east by therhyolite 

of Oddie Mountain and on the west by the later andesite. From the 

Mizpah vein a succession of branches depart, running chiefly in a 

southwestern direction from the eastern end of the outcrop, and each 

successive branch diverges more than its predecessor from the strike 

of the main vein, so that the whole group is like a section of the 

spokes of a wheel, the spokes uniting some distance east of the main 

shaft. The chief of these branches are known as the Burro No. 1, 

No. 2, No. 3, etc. They are strongest near the main vein, and those 

which diverge most from the strike of the latter are weaker than those 

which are more nearly parallel to it. The intersections of the branches 

with the main vein and with one another usually pitch to the east at 

a moderate angle. These easterly pitching intersections are significant, since they have the same general c~urse as certain shoots of 

especially rich ore in the same vein, and correspond also in direction 

to some post-mineral fracturing and faulting. The main vein has in 

general a steep northerly dip, which is locally overturned so as to dip 

steeply to the south.

The Valley View mine shows a group of veins of the same general 

type as the Mizpah, but with minor differences. The main Valley 

View vein as exposed in the workings has, like the Mizpah vein, 

a northerly dip, but is very much flatter. It is very large, and the 

rich ore in it is unequally distributed, occurring in shoots or bunches. 

As the large vein approaches the surface it splits into several somewhat smaller veins, which assume a nearly, or quite, vertical position. This vein group is in general very nearly parallel to the Mizpah group; the linked character, forking and reuniting, is quite as

well marked as in the Mizpah group; and there is some radiation in 

the strike of the veins, although not so much as in the former case. 

The Valley View veins are affected by post-mineral faulting, like the 

Mizpah vein.

The Montana Tonopah group shows a strong main vein running 

east and west and dipping north at a moderate angle. A number of 

lesser veins have been cut in the workings, and although development 

at the time of the writer's examination was comparatively slight, it is 

probable that most of these veins will eventually unite with one 

another or with the trunk vein. The indications are that the branches 

lie mostly on the north side of the trunk vein and diverge in trend 

from it, opening out to the east. These branches as a rule dip more 

steeply than the main vein, and will, therefore, also tend to unite 

with it vertically. The Montana Tonopah veins are, like the others, 

displaced by considerable post-mineral faulting.

In all these veins the union of two branches to form one is generally 

attended by corresponding enrichment, and, conversely, the place
SPURR.] OCCUEEENCE OF GEES IN THE VEINS. 21

where a small branch vein leaves the main one is generally impoverished, often to a m.uch greater degree than the size of the branch vein 

would seem to warrant. The recognition of this fact by the miners 

has led to the use of the highly descriptive term " vein robbers," for 

these small branches.

From the above it will be seen that the chief developed Tonopah 

veins have a decided east-west trend. From the fact that there is a 

predominant north-south trend in some of the chief veins of California and the western part of Nevada, east-west veins have been 

looked upon with some prejudice in Tonopah, many miners being 

inclined to doubt the value of the veins on account of their strike, 

and others forming the theory that they were simply the offshoot of a 

great undiscovered north-south vein which would prove to be vastly 

richer than these; but the Tonopah field is in an entirely different

region, geologically, from California, and this objection seems to the 

writer to have little weight. In Idaho, where the geological conditions are perhaps more like those of Nevada than they are in California, the usual trend of the veins is east and west.

Minor veins run northwest and northeast and even north and south, 

but so far as yet observed the east-west veins are the chief ones, and 

it seems likely that the mineralization will be extensive in an eastwest belt rather than in a north-south one.

OCCURRENCE OF ORES IN THE VEINS.

Physical character. The veins of the Tonopah district are usually 

strong, straight, and well defined, yet they are not fissure veins. They 

have at first sight all the appearance of fissure veins, but a little close 

examination shows that they have been formed almost entirely by 

replacement of the andesite in which they occur. They seem to have 

originated along zones of especially strong fracturing in the andesite, 

formed during a period of movement subsequent to the consolidation 

of this rock. These zones of maximum fracturing, which are usually 

4 to 6 feeb wide, but may be much wider or narrower, became the chief 

channels of circulation for the mineralizing waters. It has already 

been stated, in describing the alteration of the early andesite, that the 

andesite near the veins has been silicified to a very great extent, and 

the veins themselves seem to be the final stage of alteration, the andesite being mostly or entirely altered to quartz. A slight detailed study 

of the veins gives abundant proof of this origin, for all stages in the 

development can be seen in different portions. In many cases the 

vein consists simply of a zone of more or less altered andesite, not 

essentially different, except perhaps for a somewhat greater silicification, from the andesite which forms the walls. This zone is cut by 

parallel fractures having the same strike and dip as the walls, and the 

walls themselves are nothing more than stronger fractures of the same 

kind. In the next stage, where part of this fracture zone becomes
OftE DEPOSITS OF TONOPAH, NEVADA. [BULL. 219.

altered to quartz, the main wall fractures have been the most favorable, so that sometimes a hanging-wall streak of .quartz and a footwall streak are found with only altered andesite between (fig. 3). 

Sometimes, also, either the hanging-wall or the foot-wall streak may 

be wanting. Next, streaks of quartz parallel with the walls may be 

found, or the quartz may form a network in the andesite. Thus the 

process may be traced to the stage where the whole of the andesite is 

replaced by quartz, forming a solid vein several feet in width. As a

Fro. 3. Detailed vertical section of one of minor Valley View veins at surface.

rule, however, there is more or less decomposed andesite forming part 

of the vein.

As exceptions there are found streaks of quartz, usually small, 

within the vein, which show crustification and comb structure, and 

thus bear evidence of having been formed in cavities. These cavities, however, were of irregular shape and were not fissures, properly 

speaking, but spaces of dissolution, and were the effect of the mineralizing waters themselves.

The largest example of a crustified vein is found in certain parts of 

the Montana Tonopah workings, where the cavities were sometimes 2 

or 3 feet in diameter and gave rise to well-banded ores.
SPURB.] OCCURRENCE OF ORES IN" THE VEINS. 23

In the Montana Tonopah the chief vein shows in places a brecciation and subsequent cementation. Both the original material and 

the subsequent cement are of quartz and rich black silver ores, and 

seem to have been deposited under about the same conditions. The 

inference is that the strain which originally produced the fracture 

zones kept on during their cementation by the circulating mineralizing waters, and that in this case this strain resulted in the local 

shattering of the cement and the subsequent healing by similar 

materials.

Primary ores. At the time of the writer's first investigation of 

Tonopah, in the autumn of 1902, only the oxidized ores of the upper 

levels of the Mizpah were available for examination. From a microscopic study of these he found that the original metallic mineral was 

still present in minute grains. It was black in color, and he supposed

it to be a rich silver sulphide. Subsequent to this investigation the 

primary sulphide ores were found in the Montana Tonopah mine, and 

the correctness of the forecast above mentioned was shown. In the 

Montana Tonopah the ores are quartz veins carrying in places very 

large amounts of the rich black antimonial sulphide of silver, stephanite. This stephanite is undoubtedly primary. Besides the quartz, 

as gangue mineral, there is another having a milky appearance, 

but otherwise looking much like the quartz. This is a variety of 

orthoclase (valencianite). Some of the stephanite may contain some 

copper, making it a kind of polybasite. Chalcopyrite is very commonly present and is probably, in part at least, primary, although 

this is not certain.

Secondary sulphides. Throughout the Tonopah district argentite 

and ruby silver occur in greater or less abundance, sometimes adding 

considerably to the value of ores, but they do not occur in such quantities as the stephanite ores or the oxidized products. Wherever 

found the argentite and the ruby silver are unquestionably secondary, 

having formed from, the alteration of the stephanite. They occur 

along cracks in the primary sulphide ore and are occasionally found in 

the oxidized or semioxidized ore. The chalcopyrite above mentioned, 

as observed in the Montana Tonopah ore, seems to occur chiefly as 

small streaks cutting the original stephanite ore, giving it the appearance of being secondary to the latter. In some cases it occurs along 

cracks and is undoubtedly secondary. Ib is very likely that some at 

least of this mineral has been formed from the copper contained in 

the cupriferous silver sulphide. Some pyrite is also undoubtedly 

secondary. Pyrite, however, is relatively rare in these ores much 

more so than in the country rock.

Oxidized ores. In the Mizpah vein the oxidized zone extends nearly 

down to the 700-foot level. Observation shows, however, that the 

limit of oxidation is extremely irregular. For example, the oxidation 

extends much deeper along the vein than some distance away from, it
24 ORE DEPOSITS OF TONOPAH, NEVADA. [BULL. 219.

in the country rock. At 400 feet from, the surface the Valley View 

veins show oxidized ore, while 100 feet higher the country rock away 

from the veins is unoxidized. In the Stone Cabin shaft the change 

from the oxidized to the unoxidized andesite came just below the 200- 

foot level, but at 400 feet the ore is partly oxidized. The reason for 

this appears to be that the quartz veins, on account of their brittleness, have been more readily fractured by strains than has the softer 

country rock, and so the veins afford channels for oxidizing waters 

coining from the surface. Strong fractures, such as those in the 

vicinity of faults, have the same effect as the open fractures in veins 

and carry down the oxidizing influences to a depth of several hundred 

feet. Where the rocks are protected above by relatively impervious 

formations the oxidation may be comparatively slight. Thus, in the 

Silvertop workings (near the Stone Cabin) the later andesite is unoxidized at a depth of 120 feet. Here it is protected at the surface by a 

deposit of fine-grained, stratified tuff.

In the oxidized zone of the veins the sulphides are mostly entirely 

altered or can be made out only with a microscope, yet in many cases 

the alteration is not complete and the purple color of the richer quartz 

is as a rule due to these finely disseminated sulphides. Most of the 

sulphides, however, are altered to silver chloride, with some bromides 

and iodides, and to iron oxide. Nearly all of the ore in the Mizpah 

vein, down to the lowest depths explored, is oxidized, while the ores 

of the Montana Tonopa-h are only slightly and exceptionally oxidized. 

In the latter case the veins and the inclosing early andesite have been 

protected from the atmosphere by several hundred feet of decomposed, 

soft, later andesite, whereas in the former case the veins outcrop at 

the surface and oxidizing waters sink readily into them.

In the process of oxidation and alteration of the metallic minerals 

there has probably been some transfer of material. Little is known 

of the primary or unoxidized veins, but some portions seem almost 

entirely barren and some very rich. It will probably be found that 

these rich portions form definite shoots or masses of ore in the relatively barren veins. In the oxidized ores the values are by no means 

uniform, but seem rather better distributed than in the deeper regions. 

The indications are that during oxidation some of the values have 

been distributed from the richer portions through the more barren 

portions, producing a larger supply of fair quality ore. It is also 

likely that during this process there has been some concentration of 

values, so that the oxidized ores as a whole may be found to be somewhat richer than the sulphide ores. It is possible, for example, that 

those portions of the veins which have been eroded furnished during 

the process of erosion a small share of their precious metals to the 

underlying portions of the vein, these underlying portions now having become the present oxidized zone.

It also seems probable that in places some relatively slight transfer and redeposition of the precious metals has taken place along
SPUBB.] APPLICATION OF GEOLOGICAL PEINCIPLES. 25

the fault planes, which are later than the original veins and have displaced them. This action, however, is only exceptionally the case, 

and as a whole is insignificant. The main ore shoots of the oxidized 

portion of the Mizpah mine are regarded as primary, since evidence 

has been found that these coincide with the original ones and have 

been oxidized nearly in place; therefore it is improbable that the 

transfer of material during oxidation, bringing about local concentration or impoverishment, has been very great.

Ore shoots. In the oxidized portion of the Mizpah vein the richer 

ores lie in roughly defined; broad shoots, which pitch east on the vein. 

At least three of these shoots, parallel to one another and with poorer 

ore between, have been recognized. In the unoxidized ores of the 

Montana Tonopah there is evidence of the existence of similar shoots 

Or bunches, but enough exploration work has not been done to enable 

the writer to describe them more closely.

APPLICATION OF GEOLOGICAL PRINCIPLES.

From the short description of the occurrence of the veins which has 

been given, it is seen that it is of the first and highest importance to 

distinguish and determine, so far as possible, the position of the early 

andesite. As has been noted, this early andesite is likely to be confounded with the later andesite and with some forms of altered and 

silicified rhyolite, especially that gray, glassy rhyolite which occupies 

a considerable area in the northern corner of the district. As is seen 

on the accompanying map, the actual area where the early andesite 

outcrops is very limited, and in other portions of the district it. is 

covered by later rocks or is cut through and displaced by them. 

These later cappings may consist of the biotite-andesite, the various 

rhyolites and dacites, the volcanic breccias, or the stratified tuff formation ; or they may consist of two or more of these, superimposed 

one on the other. Those later rocks which are intrusive rather than 

in the form of flows (including some of the siliceous rhyolites, some 

of the dacites, and probably even some of the later andesites) can not 

be expected, however, to give way to the early andesite in depth. A 

shaft sunk in a dike or volcanic neck is very apt to continue in this 

same rock indefinitely downward (see fig. 4).

Of the different rocks which cap the early andesite and the included 

veins, the oldest, the later andesite, is regarded as the most favorable for prospecting; and, in the light of present knowledge, a belt of 

this rock lying east and west of Mizpah Hill is probably especially 

favorable. On the other hand, although the veins indicate a general 

east-west trend of mineralization, it is by no means proved that the 

outcrops on Mizpah Hill occupy the center of the mineralized belt and 

show the greatest mineralization. It may eventually be proved that 

the strongest portion of this belt lies north or south of the locality 

known at present, which would make the whole width of the belt con-
26 OEE DEPOSITS OF TONOPAH, NEVADA. [BULL. 219.

siderable. The whole later andesite region is worthy of careful 

yet cautious prospecting. The localities where the later andesite is 

intruded by the rhyolite ought, as a rule, to be avoided in this prospecting, for such places are not so favorable as those where the andesite is undisturbed. Such places, however, are likely to be preferred by many mining men, since they are apt to show some of the 

smaller and poorer veins of the later rhyolitic mineralization. Again, 

the region of faults should be avoided, for these faults have affected 

the ore-bearing veins, and if veins are found near them they are difficult, and sometimes almost impossible, to follow. The rocks along 

fault zones are often decomposed and the decomposed material may

Hypothetical

 deep-eeated deep-seated 

granite limestone

Hypothetical Early andesite Latei andcslw Daclte breccia Brecclated.

culler tnyolheB

Later daclte Early andcslte veins 

and rhyollte O6386' Tel"s belongIntrusions ing to other period*

PIG. 4. Ideal cross section Of Tonopah rocks. (This section does not represent any particular 

place, and is simply intended to illustrate the geological conditions, as described in the text.)

have the appearance of what is known as " vein matter." From this 

material real or fictitious assays may be obtained, and such a locality 

may appear to the miner as more hopeful than less altered rock which 

does not look like a vein and does not show any assays. Some of the 

principal faults are shown on the accompanying map, but certainly 

not all of them have been detected, and underground developments 

will probably reveal many more.

Concerning the dacites and rhyolites of the later intrusions, the 

volcanic necks and the dikes should, as a rule, be avoided by prospecting operations. The greater parts of the principal low mountains 

and hills in the vicinity, such as Butler, Brcugher, Siebert, most of 

Golden, etc., are regarded as offering very little hope for prospecting, 

and even near the rhyolite hills, like Rushton, Oddie, and Ararat, 

there has been a 'displacement of the veins, for the hills are essentially intrusive. The writer is aware that the proximity of the rich 

veins of Mizpuh Hill to Oddie Mountain has caused this mountain to be
APPLICATION OF GEOLOGICAL PRINCIPLES. 27

regarded with great favor, but the fact that the veins are in this position has no connection with the mountain; they are there rather in 

spite of the mountain than by virtue of it, and it would certainly have 

been'much better for mining operations if the rhyolite had not been 

erupted and the mountain formed.

Most of the dacite breccias and some of the brecciated rhyolite are 

in the nature of flows, and may be sunk through by shafts to lower 

formations, such as the later andesite or the early andesite. Much of 

the fine-grained, brecciated rhyolite, however, is intrusive, so that, as 

a rule, this rock also is not a good place to sink, except with caution.

The tuff formation, of course, is always sedimentary and can be sunk 

through to reach the underlying formation, which may be any one of 

the older rocks.

To sum up, then, the later andesite is the most favorable of the 

capping rocks; the pumiceous dacite breccia with interstratified,

coarse, tuffaceous rocks is next, while the brecciated rhyolite should 

be prospected very cautiously to see whether it is intrusive. The tuff 

may be pierced to discover the underlying rock where the geological 

relations do not make this plain, while intrusive dacite and rhyolite 

necks should be approached very cautiously indeed.

It must be understood that these characterizations apply only to the 

immediate vicinity of Tonopah, or the Tonopah district proper. On 

account of the sudden rise and fame of the camp the name Tonopah 

has spread far beyond its limits, and has been applied to mines lying 

in quite other districts, sometimes 50 or 60 miles away. Here, and 

also in neighboring districts which have not borrowed the name Tonopah, the geological conditions are different. In the Gold Mountain 

district, for example, about 4 miles south of Tonopah, the veins lie 

in rhyolites and tuffs and evidently belong to therhyolitic period; yet 

they carry in some cases considerable values in gold and silver.

The position of the early andesite away from the outcrops can be 

foretold to only a limited and uncertain extent, for in dealing with a 

complex of volcanic flows and dikes like that in Tonopah there is no 

rule which governs their distribution and by which their position in 

an unknown locality can always be defined with certainty. Therefore, the prospecting should be done cautiously and the district should 

be developed from the known region as a center; thus little by little 

a greater knowledge of the geological detail will be gained. On 

account of the lack of certainty of results in this work, in many 

cases it'would probably be more economical, both of time and of 

money, to explore with a diamond drill rather than with shafts. 

Certainly the sinking of a two- or three-compartment shaft in an 

unproved portion of the district is often unwise.

The early andesite once located, the question of finding the veins 

remains, and after that the question of. finding pay ore within the 

veins. The geological evidence goes to show that the mineralizing
28 OEE DEPOSITS OF TONOPAH, NEVADA. [BULL. 219.

waters which produced the early andesite veins were unusually active, 

and a large amount of vein formation is indicated. It is beyond 

question, therefore, that the veins thus far found are only a fraction 

of those which exist in the vicinity. These veins will be chiefly 

unoxidized, since they are protected from oxidation by capping rocks. 

In them undoubtedly large portions probably much the larger portions will be relatively barren quartz, in which shoots, chimneys, or 

irregular bunches of rich ore may be expected to a considerable depth. 

These quartz veins, carrying silver and gold and occurring in Tertiary andesite, belong to a larger group of veins occurring in similar 

andesite and found along a north-south zone. These veins are exemplified by the Comstock in Nevada and by the important district of 

Pachuca in Mexico. Probably Pachuca is the nearest analogue, and 

its description, as given by the Mexican geologist, Ordonez, may be 

of value in considering the characters of the Tonopah veins. Judging 

from these districts it is possible that in depth a rather larger proportion of the baser metals, such as copper, and possibly lead and zinc 

(although no traces of the last two have as yet been found in the 

veins), may come in, and that the values in,gold and silver may 

decrease somewhat. This, however, if it happens, should do so at a 

considerable depth.
INDEX.

Andesite, methods of distinction in general. 13,14

Andesite, early, difficulty of distinguishing. 13

distribution and characteristics of.... . 12,13

eruption of .............. 9

Andesite, later, difficulty of distinguishing. 13 

distribution and characteristics of ..... 13

eruption of ............................. 10

Ararat Hill, lava of......................... 14

Argentite, occurrence of.................... 16,23

Basalt,eruption of.......................... 10

Belle of Tonopah shaft, rock in which located ............................... 14

Big Tono shaft, rock in which located ..... 15

Boston Tonopah shaft, in later andesite.... 13

Brougher, W., interests of, in original claims. 7 

Brougher Mountain, basin partly inclosed

by .................................. 14

reference to ......................... 10,11,26

Butler, J.L., discovery of the Tonopah ores

by .................................. , 7

Butler Mountain, altitude of ............... 9

basin partly inclosed by................ 14,26

Calcite, occurrence of....................... 17

California Tonopah mtne, reference to .... 8,19

Chalcedony, occurrence of........'......... 17

Chalcopyrite, occurrence of............. 16,17,23

Climate of Tonopah, characteristics of..... 7

Comstock district, comparison of veins of.. 28 

Copper, occurrence of, in veins formed subsequent to early andesite intrusion. 16 

possibility of larger proportion of, in

depth............................... 28

Dacite, later intrusive, distribution and

characteristics of................... 15

Dacite eruptions and later intrusions ...... 10,11

Dacite-breccia formation, distribution and

characteristics of................... 15

Dacites, distribution and characteristics of. 14,15 

Discovery of the ores and development of

the claims.......................... 7-9

Erosion, recent............................. 12

Erosion interval between the two andesites. 15 

Fault planes, redeposition of metals along. 24,25 

Faulting, economic interest in............. 12

occurrence and character of........... 11

Faults, principal ones shown on map...... PI. I

Fraction mine, early andesite rock in ..... 13,14

Fraction No. 1 shaft, rock in which located. 15 

Fraction No. 2 shaft, rock in which located. 15 

Fraction No. 3 shaft, rock in which located. 15

Page.

Future possibilities in the district, geological evidence of.................... 28

G. & H. tunnel, in white rhyolite .......... 14

Galena, occurrence of...................... 17

Geological conditions, represented by ideal

cross section of Tonopah rocks..... 26

Geological formations, pre-Tertiary........ 9

Geological formations and events in the

district, sequence of................ 12

Geological history of the district........... 9-12

Geological principles, application of....... 25-28

Gold, proportion of, to silver by weight in 

veins formed subsequent to early 

andesite intrusion.................. 16

proportion of, to silver in the ores...... 9

Gold, free, occasional occurrence of........ 16

Gold Hill, outcrop of early andesite on.... 12

Gold Mountain, veins of rhyolitic period, 

characteristics and metallic content................................. 17

Gold Mountain district, reference to....... 27

Golden Anchor shaft, in later andesite..... 13

Golden Mountain, reference to dacite contacton.............................. 16

Granite of the region, intrusive in limestone................................ 9

Halifax shaft, in later andesite............. 13

Heller Butte, character of rock composing.. 14 

King Tonopah shaft, rock in which located. 14 

Knox, C. E., information furnished by..... 8

Lake sediments............................. 10

Lead, possibility of finding, in depth....... 28

Leases in 1900 and 1901...................... 7

Limestone of the region.................... , 9

Little Tonopah shaft, in later andesite..... 13

MacNamara mine, early andesite rock in.. 13,19 

Map showing veins outcropping at Tonopah ................................. 19

Map, geologic, of Tonopah district......... PI. I

Map, topographic, of the region, reference

to................................... 9

Microscopic examination of primary ores.. 23 

Midway mine, early andesite rock in ...... 13

Mineralization at contacts of large dacite

necks, character of................. 17

periods and nature of.................. 15-18

subsequent to dacite intrusions ........ 17

subsequent to early andesite intrusion.. 15 

subsequent to early rhyolite intrusion.. 16 

subsequent to later rhyolite intrusion.. 16

29
30 INDEX.

Page. 

Mineralization and hot-spring action at

Tonopah, resume1 of ................ 17-18

Miriam shaft, rock in which located....... 14

Mizpah group of veins, period of formation,

importance and character of..'..... 16

Mizpah Hill, main groups of veins ......... 19'

outcrop of early andsite on ............ 12

Mizpah Hill veins, development of........ 19

Mizpah mine, shipments from ............. 8

Mizpah vein, characteristics of branches of. 20 

horizontal plan of portion of, at 250-foot

level................................ 18

limit of oxidized zone in ............... 23

oxidation of ore in ..................... 24,25

Molly shaft, rock in which located......... 15

Montana Tonopah chief vein, brecciation

and subsequent cementation....... 23

Montana Tonopah group of veins, characteristics of.......................... 20

period of formation, importance, and

character of........................ 16

Montana Tonopah mine, shipments from to

July 15,1903........................ 8

Montana Tonopah shaft in later andesite.. 13

Mount. Gee next word of name.

New York Tonopah shaft, rock in which

located............................. 14

North Star mine, early andesite rock in.... 13

North Star tunnel, in white rhyolite....... 14

Oddie, T. L., connection of, with discovery

and development of the district.... 7

information furnished by .............. 8

Oddie Hill, lavaof ......................... 14

Oddie Mountain, rhyolite of, compared

with later intrusive dacite......... 15

some misconceptions concerning....... 27

Ohio Tonopah mine, early andesite rock

in.....:.......................... 13,14,19

rhyolite in vicinity of .................. 14

Ordonez, Ezequiel, reference to ............ 28

Ore, weight and value of, shipped to April

1,1903.............................. 8

Ore shoots, veins where recognized........ 25

Ores, occurrence of, in the veins........... 21-25

proportion of gold to silver values in .. 9

secondary sulphides, characteristics of. 23

Ores, oxidized, limits and characteristics of. 23-25

some mineral consti tuents of........... 16

Ores, primary characteristics of............ 23

microscopic examination of............ 23

Ores, sulphide, of veins formed subsequent

to early andesite intrusion ......... 16

Pachuca district, Mexico,. comparison of

veins of............................. 28

Pegmatite in volcanic breccias ............ 9

Polybasite, occurrence of .................. 16,23

Population of Tonopah camp, estimate of.. 7 

Prospecting, localities and rocks not very

favorable for....................... 26,27

most favorable rocks for, above the ' 

early andesite...................... 25

probable favorable location for......... 25

region worthy of ....................... 26

suggestions as to economical methods

of................................... 27,28

Pyrite, occurrence of.................... 16,17,23

Page. 

Rescue shaft, in white.rhyolite............. 14

Rhyolite, methods of distinguishing'from

andesite............................ 14

Rhyolite eruptions and later intrusions.... 10,11

Rhyolites, distribution and characteristics

of................................... 14

Rocks of the region, description of......... 12-] 5

Ruby silver, occurrence of ................. 16,23

Rushton Hill, lava of....................... 14

Siderite, occurrence of...................... 17

Siebert Mountan, basin partly inclosed by. 14 

reference to ......................... 10,11,26

Silver, proportion of, to gold by weight in 

veins formed subsequent to early 

andesite intrusion.................. 16

proportion of, to gold in the ores....... 9

Silver bromide, occasional occurrence of .. 16 

Silver chloride, occurrence of...'........... 16

Silvertop shaft, rock in which located..... 14

Silvertop workings, unoxidized rock near

surface in........................... 24

Stephanite, primary, occurrence of ........ 16,23

Stone Cabin shaft, limit of oxidized ore in. 24 

Sulphides, alterations of.................... 24

Tonopah, altitude of........................ 9

location of.............................. 7

Tonopah City shaft, rock in which located. 15 

Tonopah Mining Company, development

work by............................ 7

Topography of the region.................. 9

Transportation facilities to the camp ...... 7

Tuffs and volcanics of the district.......... 9

Valencianite, reference to.................. 16,23

Valley View, group of veins, characteristics

of................................... 20

i detailed vertical section at surface of

one of ...................:.......... 22

limit of oxidized ore in................. 24

period of formation, importance and

character of ......*.................. 16

Value of ore shipped to April 1,1903........ 8

Values in gold and silver of veins of rhyolite

period at Gold Mountain........... 17

in precious metals at contacts of large 

dacite necks........................ 17

in the ores, proportion of gold to silver. 9 

Values, comparative, in gold and silver in 

veins subsequent to later rhyolite 

intrusions .......................... 17

Vein, crustifled, example of, in Montana

Tonopah workings................. 22

Vein deposition, evidence showing age of. 15 

Vein groups of early andesite mineralization ................................. 18-21

"Vein robbers," use of the term ........... 21

Veins, bearing of direction of trends on

values.............................. 21

difficulty of ascertaining age of........ 18

earliest and most important class of,

rock where found .................. 17

enrichment and impoverishment of.... 20,21

exceptions to replacement type........ 22

formation of, by replacement of andesite 21 

gangue material of those formed subsequent to early andesite and early 

rhyolite intrusions ................. 16
INDEX. 31

Page. 

Veins, "linked type ".of, characteristics

of................................... 18

means of formation of.................. 16

most important, in Tonopah district,

kind of rock occurring in .......... 15

of early andesitic period, range of discoveries of........................... 19

physical character of................... 21

subsequent to early rhyolite intrusion, 

 character and metallic content of.. 16

subsequent to early rhyolite intrusion, 

difficulty of distinguishing from 

andesitic veins ..................... 16

subsequent to later rhyolite intrusion,

character and metallic content of.. 17

Page. 

Veins, productive, age of................... 18

Veins, rhyolite, rocks in which they may

occur............................... 17

Volcanic necks............................. 11,16

Volcanics and tuffs of the district.......... 9

Wandering Boy mine, early andesite rock in 13,15 

Wandering Boy shaft, rock in which located ............................... 15

Waters, hot, ascending, concerned in production of veins subsequent to early 

andesite and early rhyolite intrusions.. .............................. 16

West End mine, reference to............... 8

West End shaft, rock in which located..... 15

Zinc, possibility of finding, in depth ....... 28

o

PUBLICATIONS OF UNITED STATES GEOLOGICAL SURVEY.

[Bulletin No. 219.]

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 A.tlas of 

United States folios and separate sheets thereof, (8) Geologic Atlas of 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 classified 

into the following series: A, Economic geology; B, Descriptive geology; C, Systematic geology and paleontology; D, Petrography and mineralogy; E, Chemistry and 

physics; F, Geography; G, Miscellaneous; H, Forestry; I, Irrigation; J, Water storage; K, Pumping Avater; L, Quality of water; M, General hydrographic investigations; N, Water power; 0, Underground waters; P, Hydrographic progress reports. 

This bulletin is the twenty-seventh in Series A, and the thirty-third in Series B, the 

complete lists of which follow. (B = Bulletin, PP = Professional Paper, WS = 

Water-Supply Paper.)

SERIES A, ECONOMIC GEOLOGY.

B2], Lignites of Great Sioux Reservation: Report on region between Grand and Morcau rivers,

Dakota, by Bailey Willis. 1885. 1C pp., 5 pis. (Out of stock.) 

B 40. Nature and origin of deposits of phosphate of lime, by R. A. F. Penrose, jr., with introduction

by N. S. Shalcr. 1888. 143pp. (Out of stock.) 

B 05. Stratigraphy of the bituminous coal field of Pennsylvania, Ohio, and West Virginia, by I. C.

White. 1891. . 212 pp., 11 pis. (Out of slock.) 

B 111. Geology of Big Stone Gap coal field of Virginia and Kentucky, by M. K. Campbell. 1893. 100

pp., 0 pis.

B 132. The disseminated lead ores of southeastern Missouri, by Arthur Winslow. 189G. 31 pp. 

BJ38. Artesian-well prospects in Atlantic Coastal Plain region, by N. IT. Darton. 1890. 228 pp., 19

pis. (Out of stock.) 

B 139. Geology of Castle Mountain mining district, Montana, by W. H. Weed and L. V. Pirsson 1890.

IC-lpp., 17 pis.

B 1'13. Bibliography o£ clays and the ceramic arts, by J. C. Brainier. 1890. 114 pp. 

B 104. Reconnaissance 011 the Rio Grande coal fields of Texas, by T. W. Vaughan, including a report

on igneous rocks from the Sau Carlos coal field, by E. C. K. Lord. 1900. 100 pp., 11 pis. 

B 178. El Paso tin deposits, by W. H. Weed. 1901. 15 pp., 1 pi. 

B 180. Occurrence and distribution of corundum in United States, by J. H. Pratt. 1901. 98 pp.,

14 pis. 

B 182. A report on. the economic geology of the Silverton quadrangle, Colorado, by F. L. Ransome.

1901. 200 pp., 10 pis. (Out of stock.) 

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. 04 pp,, 10 pis. (Out of

stock.) 

B 193. The geological relations and distribution of platinum and associated metals, by J. F. Kemp.

1902. 95 pp., C pis. (Out of stock.)

. B 198. The Berea grit oil sand in the Cadiz quadrangle, Ohio, by W. T. Griswold. 1902. 43 pp., 1 pi. 

I'Pl. 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'silver in shales from western Kansas, by Waldemar Lindgren. 1902. 21 pp. 

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 Dnll, Kanuti, Alien,

and Kowak rivers, by W. C. Mendenhal.l. 1902. 08 pp., 10 pis.

PP 11. Clays of the United States east of the Mississippi River, by Heinrich Kies. 1903. 298 pp., 9 pis. 

PP 12. Geology of the Globe copper district, Arizona, by F. L. Ransome. 1903. 108 pp., 27 pis.

Bull. 219 03 3 i
IT ADVEETISEMENT.

B 212. Oil fields of the Texas-Louisiana Gulf Coastal Plain, by C. W. Hayes and William Kennedy.

1903. 174 pp., 11 pis. 

B213. Contributions to economic geology, 1902; S. F. Emmoiis, C. W. Haves, geologists in charge.

1903. 449pp. 

FP 15. The mineral resources of the Mount Wrangell district, Alaska, by Walter C. Mendenhall and

Frank C. Schrader. 1903. 71 pp., 10 pis.

B21S. Coal resources of the Yukon, Alaska, by Arthur J. Collier. 1903. pp., C pis. 

B 219. The ore deposits of Tonopah. Nevada (preliminary report), by ,T. E,Spnrr. 1903. 31 pp., 1 pi.

SERIES H. DESCRIPTIVE GEOLOGY.

B 23. Observations on the junction between the Eastern sandstone and the Keweenaw series on

Keweenaw Point, Lake Superior, by K. D.'Irving and T. C. Chamberlin. 1885. 124 pp., 17 pis. 

B 33. Notes on geology of northern California, by ,T. S. Diller. 1886. 23 pp. (Out of stock.) 

B 39. The upper beaches and deltas of Glacial Lake Agassiz, by Warren Upham. 1887. 84 pp., 1 pi.

(Out of stock.) ' 

B 40. Changes in river courses iu Washington Territory clue to glaeiatiqu, by Bailey Willis. 1887.

10 pp., 4 pis. (Out of stock.) 

B 45. The present condition of knowledge of the geology of Texas, by R. T. Hill. 1887. 94pp. (Out

of stock.)

B 53. The geology of Nantucket, by N. S. Shaler. 18S9. 55 pp., 10 pis. (Out of stock.) 

B 57. A geological reconnaissance in southwestern Kansas, by Kobert Hay. 1890. 49 pp., 2 pis. 

B 58. The glacial boundary in western Pennsylvania, Ohio, Kentucky, Indiana, and Illinois, by G. F.

Wright, with introduction by T. C. Chamberlin. 1890. 112 pp., 8 pis. (Out of stock.) 

B 67. The relations of the traps of the Newark system in the New Jersey region, by N. H. Barton.

1890. 82pp.

B 104. Glaciation of the Yellowstone. Valley north of the Park, by W. H. Weed. 1893. 41 pp., 4 pis. 

BIOS. A geological reconnaissance in central Washington, by I. C. Russell. 1893. 108 pp., 12 pis.

(Out of stock.)

B 119. A geological reconnaissance in northwest Wyoming, by G. H. Eldridge. 1894. 72 pp., 4 pis. 

B 137. The geology of the Fort Riley Military Reservation and vicinity, Kansas, by Robert Hay.

1896. 35 pp., 8 pis.

B 144. The moraines of the Missouri Coteau and their attendant deposits, by J. E. Todd. 1896. 71 

 pp., 21 pis. 

B 158. The moraines of southeastern South Dakota and their attendant deposits, by J. E. Todd.

1899. 171 pp., 27 pis. * 

B 159. The geology of eastern Berkshire County, Massachusetts, by B. K. Emerson. 1899. 139 pp.,

9 pis. , " ' , . B 165. Contributions to the geology of Maine, by IT. S. Williams and H. E. Gregory. 1900. 212 pp.,

14 pis.

WS 70. Geology and water resources of the Patrick and Goshen Hole quadrangles in eastern Wyoming and western Nebraska, by G. I. Adams. 1902. 50 pp., 11 pis. 

B 199. Geology and water resources of the Snake River Plains of Idaho, by I. C. Russell. 1902. 192

pp., 25 pis. 

PP 1. Preliminary report on the Ketchikan mining district, Alaska, with an introductory sketch of

the geology of southeastern Alaska, by A. H. Brooks. 1902. 120 pp., 2 pis.

PP 2. Reconnaissance of the northwestern portion of Seward Peninsula, Alaska, by A. J. Collier. 

1902. 70 pp., 11 pis.

PP 3. Geology and petrography of Crater Lake National Park, by ,T. S. Diller and H. B. Patton. 

1902. 167pp., 19 pis.

PP 10. Reconnaissance from Fort Hamliii to Kotzebue Sound, Alaska, by way of Ball, Kanuti, 

Alien, and Kowak rivers, by W. C. Mendenhall. 1902. 68 pp., 10 pis.

PP 11. Clays of the United States east ol the Mississippi River, by Heinrich Rie.s. 1903. 298 pp., 9 pis.

PP 12. Geology of the Globe copper district, Arizona, by F. L. Ransome. 1903. 168 pp., 27 pis.

PP 13. Drainage modifications in southeastern Ohio and adjacent parts of West Virginia and Kentucky, by W. G. Tight.' 1903. Ill pp., 17 pis.

B 208. Descriptive geology of Nevada south of the fortieth parallel and adjacent portions of California, by J. E. Spurr. 1903. 229 pp., 8 pis.

B 209. Geology of Ascutney Mountain, Vermont, by R. A. Dnly. 1903. 122 pp., 7 pis.

WS 78. Preliminary report on artesian basins in southwestern Idaho and southeastern Oregon, by 

I. C. Russell. 1903. 51 pp., 2 pis.

PP. 15. Mineral resources of the Mount Wrangell district, Ala-ska,, by W. C. Mendenhall and F. C.. 

Schrader. 1903. 71 pp., 10 pis.

PP 17. Preliminary report on the geology and water resources of Nebraska^vest of the one hundred 

and third meridian, by N. H. Barton. 1903. 69 pp., 43 pis.

B 217. Notes on the geology of southwestern Idaho and southeastern Oregon, by I. C. Russell. 1903. 

83pp., 18 pis.

B 219. The ore deposits of Tonopah, Nevada (preliminary report), by J. E. Spurr. 1903. 31 pp., 1 pi.

Correspondence should be addressed to

THE DIRECTOR,

.UNITED STATES GEOLOGICAL SURVEY,

WASHINGTON, D. C. 

DECEMBER, 1903.
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 the additional numbers should be added, as received, to the first 

entry.]

Spurr, J[osiah] E[dward]

. . . The ore deposits of Tonopah, Nevada, prelimii nary report; by J. B. Spurr. Washington, Gov't print. 

| off., 1903.

31, iii p. 1 pi. (map), 4 fig. 23£cra . (U. S. Geological survey. Bulletin 

no. 219.)

Subject series A, Economic geology, 27; B, Descriptive geology, 33.

Spurr, J[osiah] E[dward].

j ... The ore deposits of Tonopah, Nevada, prelimij nary report; by J. E. Spurr. Washington, Gov't print, 

off., 1903.

31, iii p. 1 pi. (map), 4 iig. 23£cl". (U. S. Geological survey. Bulletin 

nO. 219.)

Subject series A, Economic geology, 27;.B, Descriptive geology, 33.

U.S. Geological survey.

« Bulletins.

| no. 219. Spurr, J. E. The ore deposits of Tonopah, 

Nevada, preliminary report. 1903.

t U. S. Dept. of the Interior.

| see also

a U. S. Geological survey.