1/ll~~~~fi(~~·~~~~~~~~~~~~~ll/~l~ll 3 1819 00083122 8 

, :;ofessional Paper No. 55 , ti, Economic Geology, 77 

Series , Descriptive Geology, 96 , Petrography and Mineralogy, 33 

DEPARTMENT OF THE INTERIOR 

UNITED STATES, G~OLOGICAL SURVEY 

CHARLES D. W ALC01'T, DIRECTOR 

OR.E .DEPOSITS 

OF THE 

SILVER PEAK QUAl)RANGLE, NEv1IL~ 

BY 

•I 

JOSIAH EDWARD SPURR 

: : . .. .. ·. .. . .. . . : : "•o : •• :.! ".: : ...... !:"• :. ! e~ • "•"• "•• • 2"• 1'1 •• ••"• • • • 6: ~2t\o" : ...... ·.: .. .. . . .. tJ --~ : ::.:~ ..... ·::· ·.: : ::··.:·· : . .... . · .. ·: · .... : .. ·: : : :··. :·: .·.· :.· ·.: 

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25228 

WASHINGTON 

GOVERNMENT PRINTING OFFICE ( 

1906 
Nf'\! 

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·.: :-:::. :-::·-:: . . . . . . ........ . e e e .De e •• e e e ••• 

... . : ... : .. :: : .. · . . ·: : : · .. · .. · 
CONTENTS. 5 

CHAPTER IlL--GENETIC RELATIONS OF METALLIFEROUS ORE DEPOSITS-Continued. Page. 

The Drinkwater type of gold mines of Mineral Ridge--continued. 

Concentration of gold........ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 

Subsequent mineralization...... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 

Relations of the greenstone or altered diorite.............................. . . . . . . . . . . . . . 111 

General conclusions ........................ __ .. _ ........... _. . . . . . . . . . . . . . . . . . . . . . . . 112 

Analogous cases elsewhere in the quadrangle ... _....................................... 117 

The Dividend group of prospects in the Windypah district. .. _ .... _._................ 117 

Genetic relations of the Great Gulch ores ................................... _ .. _. . . . . . . . . . . . 117 

Genetic relations of the silver mines of Mineral Ridge __ ..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 

Characteristics of the Pocatello group ...... _ .............................. _. . . . . . . . . . . . 118 

Characteristics of the Black Warrior group ........ _. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 

Common characteristics of Pocatello and Black Warrior groups ............... _ . . . . . . . . . . . 119 

Genetic relations of the Lone Mountain group of mines .................... _ . . . . . . . . . . . . . . . . . 120 

Genetic relations of ores in the southern part of the quadrangle._ ............ _. . . . . . . . . . . . . . . . 121 

General conclusions as to origin of metalliferous ores. _ ........... _. . . . . . . . . . . . . . . . . . . . . . . . . . 122 

Comparison of Silver Peak deposits with other ores......... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 

CHAPTER JV.-DEVELOPMENT OF THE THEORY OF METALLIFEROUS VEINS OF MAGMATIC QUARTZ..... 129 

Crystallization of granite ................... _ ............... _ ....... __ . . . . . . . . . . . . . . . . . . . . 129 

Magmatic origin of certain pegmatites and certain quartz veins.... . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 

Concentration of metals other than gold in dikes of granitic pegmatite and of quartz ...... _.. . . . 138 

Iron in pegmatite .............. _ ......................................... _. . . . . . . . . . 138 

Copper in pegmatite....... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 

Tin, tungsten, molybdenum, antimony, bismuth, and lithium in pegmatite ................ _ 139 

Presence of gold in magmatic quartz veins which are dependent upon granitic intrusions......... 142 

Europe ............................................................................ 142 

Africa ... __ ..... _ ............ _ ............................... _ . . . . . . . . . . . . . . . . . . . . . 143 

Australia .... _ .. _ ............ _ .... _................................................ 143 

Asia .............. _ ............ _ .................. _ .......................... _ . . . . . 145 

South America .. _ ................... _.............................................. 145 

BraziL ...... __ ... _ .. _ ....... _._._............................................. 145 

Chile .......................................................................... 149 

Guiana ........... ---·······-···································-·············· 149 

North America .................. _ ............... _ .. _............................... 151 

British America .......................................... _. . . . . . . . . . . . . . . . . . . . . . 151 

Alaska .............. _ ..... _. _ ................ _ ...... _. . . . . . . . . . . . . . . . . . . . . . . . . . 152 

United States ............. _.................................................... 153 

Mexico ...... __ .. _ .... _ ........... _. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156 

CHAPTER V.-DEPOSITS m• NOKMETALLIFEROUS MINERALS._.................................... 157 

Alum and sulphur ................... _ ....... _._ ................ _ .......... _............. 157 

Locality ...................... __ .. __ .................. __ .................... __ .... _ 157 

Mode of occurrence ........ _ .. _ ......... _ ........... _ ...... _ ........... _ ........ _ ... _ 157 

Manner of formation .... _ ........ _ ...... _. _ ..... _ ..................... __ . . . . . . . . . . . . 158 

Commercial aspects ................. _ ... _ ....... _ . _ ... _ ........... _ . _ ............. _ . 158 

Borates and salt ................. _ ............. _ ..... _ ................... _ ...... _ . . . . . . . 158 

Description of deposits ..... _ .... _ ...... _ ........... _ ....... _. . . . . . . . . . . . . . . . . . . . . . . . 158 

Relation to other areas.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160 

Genesis of the deposits.............. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160 

CoaL.................................................................................. 165 

Geologic conditions........ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165 

Description of the coaL....... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165 

Probable value...... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168 

INDEX..................................................................................... 169 
ILLUSTRATIONS. 

Pa~ 

PLATE I. Geologic map of the Silver Peak quadrangle __ . ___ .. __ • _________ . ___ .. ________ . _. _ In pocket. 

II. A, Recent basaltic cone near Silver Peak; B, Mill at Silver Peak________________________ 26 

III. A, Frontal wash apron, edge of Silver Peak fiat; B, Detrital apron fringing mountains .. ___ 28 

IV. A, Wash apron, Lone Mountain region; B, Layering of subaerial wash, edge of wash apron. 28 

V. Isolated hill of Cambrian limestone surrounded by a playa deposit. __________________ . _. _ 30 

VI. Claim map of Blair mines and Tietjen mines _________________ . _________________ . ____ . _ 34 

VII. A, Open-cut workings on Crowning Glory lens zone; B, Entrance to upper workings, Drinkwater mine ___________ . _________ .. __________ . _________________ .. ___ . ____ . ___ ... _ 36 

VIII. Horizontal plan showing geology of Hickey tunnel workings ____________ .. __ ... ___ ... _ _ _ 36 

IX. Vertical cross section of Crowning Glory-Drinkwater ore zone __________ ... __ ... _ ... ___ . . 38 

X. Vertical cross section of Drinkwater mine workings ____ . ___ . ____ .. _ .... _ ... __ ... __ .... _ 38 

XI. Maps of chief stope workings, Drinkwater mine: A, Workings in upper part of zone; B, 

Workings in middle of zone; 0, Workings in lower part of zone.______________________ 40 

XII. Vertical cross section of chief stope workings, Drinkwater mine. _____ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 40 

XIII. A, Pegmatitic quartz forming veinlets in earlier crystallized feldspar; B, Gneiss due to 

injection of limestone shale by alaskitic materiaL ____ . ____ . _________ .. __ ... _ ... ___ . _ 42 

XIV. Arrangement of quartz and feldspar in alaskite dike _________________ . ___ .. __ ... _ ... _. _ 46 

XV. Portion of Pl. XIV enlarged ____ . _________ . ______________ . _________ . ____ . ___ . ___ ... _ 48 

XVI. A, Segregation of quartz and alaskite into large bunches; B, Segregation of quartz and alaskite into bunches. ___________________________ ... __ .. _________ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 98 

XVII. A, Veinlets of magmatic quartz in fine-grained alaskite; B, Original gneissoid structure in 

alaskite ____________________________________ . _____________ . ____ . ________ . ____ . _ _ 100 

XVIII. A, Original pyrite in granitic phase of alaskite; B, Muscovitized orthoclase crystal inclosed 

in fresh orthoclase ___________________________________ .. _________ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 102 

XIX. A, Chain-like arrangement of quartz grains in alaskite; B, Grouping of magmatic quartz 

grains in chains __________ . ____ .. ____ .. __ ......... _____________ .. __ . _____ . ___ . _ _ _ 104 

XX. A, Two generations of crystallization in alaskite; B, Crystallization of later quartz in interstices of earlier feldspar _____________ .... _ ... _ .... ____ . _________ . _________ . ___ . _ _ _ 106 

XXI. A, Paymaster mine, Lone Mountain district; B, Corrugated, thin-bedded limestone, Mineral 

Ridge. __________________________________________ .. ___ ... __ .. __ .. ___ .. ___ .. ___ . _ 108 

XXII. Genesis of magmatic quartz vein in alaskite. ______________ .. ____ . ___ ... ___ . ___ . ___ .. _ _ 116 

XXIII. Opening on coal seam; William Grozenger, discoverer of the field, standing by ... _ .. ____ .__ 164 

XXIV. Coal fields at north end of Silver Peak Range _______ . _. ___ .. ____ . ___ ... _ ... ___ . ___ . _ _ _ 166 

Fw. 1. Sketch section in canyon wall below Drinkwater mines .. __ ... __ .... _ .... _ ... _ ... __ .. __ .. _ 39 

2. Lenses of siliceous alaskite passing into quartz._. _ ... ___ ... _ ... ___ ... _ .. __ . _ .. __ ... _ .. _ _ 40 

3. Vertical surface section at Blair mines ... ___ ...•.......... _. _ ....... _ ......... _ ....... _ 41 

4. Intrusive diorite splitting earlier quartz lens_ .... _ ...•..... _ ..... _ .. __ . . . . . . . . . . . . . . . . . . 44 

5. Lens of quartz and alaskite in schist. __ .. _ ... _ . __ ... _. _ ....• _ ......... _ ... _. . . . . . . . . . . . 45 

6. Minor faulting in alaskite and thin-bedded limestone .. _. ___ ....•.........•... -.- ......•. _ _ 51 

7. Diagram of lenses, Homestake and Western Soldier mines ... _ .... _ .... _ .............. __ .. 52 

8. Cross section on Homestake property __ ... _ .. __ . _ ..... _ ..... _ ... _. . . . . . . . . . . . • . . . . . . . . . 53 

9. Geologic section along Mary tunneL _. ___ ....... _. ___ ... _ .. __ . _ .. ___ ... __ ... ____ .. _.... 55 

10. Vertical section, Frank No. 2 workings. __ .. ____ ... _ .............. _ .... _. . . . . . . . . . . . . . . . 59 

6 
;.._: 

ILLUSTRATIONS. 

FIG. 11. Vertical section, Golden Eagle workings . _ .... __ .... __ ... __ ... __ .... ___ .. _____ . ____ . __ _ 

12. Diagram of outcrop of Crescent lens zone_. _ .. ____ .. __ ... ___ .. ___ ... _. _ .. _____________ _ 

13. Vertical longitudinal section of Vega ore lens . __ .... _ .... __ .•. ____ .. ____ . _____ . _______ _ 

14. Vertical cross section of Vega ore lens ... _______________ . _________________ . ___________ _ 

15. Alaskite cutting across shaly limestone ___ .... ____ .. __ . _. ___ .. ____ .. ____ . _____ .. _. ___ .. 

16. Occurrence of ore in Great Gulch mine _ . ____________________________________________ .. 

17. Ore at upper contact of quartz lens, Great Gulch mine .... ___ .. ___ ... ___ .. ____ . ________ _ 

18. Ore along fault plane and stratification planes, Great Gulch mine __ ._ .. __________________ _ 

19. Quartz in schist, Pocatello mine .. _____ . ___ . _____ .. ___ .. ____ . ____ .. ___________ . ______ _ 

20. Faulting along ore zone at Pocatello mine ________________________ . ___________________ _ 

21. Diorite cutting schist and quartz, Pocatello mine ________ . ___ .. ____ .. __________________ _ 

22. Greenstone cutting schist and quartz, Vanderbilt mine ___ . ___ .. ___ ... ____ . _____ ........ . 

23. Greenstone surrounding a small quartz lens, Vanderbilt mine ......... _ .......... __ .... _. 

24. Vertical cross section of Black Warrior workings ...................................... . 

25. Relations of quartz and diorite, Foley's prospect ... _ .... __ ... _ ... __ ...... _ .... __ .... _ .. 

26. Vertical cross section of Paymaster vein .. _ ...... _ .... _ ........ __ ................... _ .. 

27. Cross section of interb~dded vein, Utopia prospects ......................... _ ......... _. 

28. Vein along fault zone, Utopia prospects ..... _ ............. _ ............. _ .... _ ...... _. 

29. Cross section of Enterprise ore zone ... _ ...... __ .... _ ... __ .. _. _ ..... ___ ... ___ . _. __ .... _ 

30. Enterprise ore zone, showing stra.tified arrangement of different materials _ ... ___ . _ .. _ . __ .. 

31. Formation of dolomite marble by mineralizing solutions, Enterprise ore zone. _____ .... _ .. _. 

32. Vertical section of ore bodies, Nevada Alpine mine ..... _ .................. __ ... __ ..... _ . 

33. Vertical s~ction of ore bodies, Nevada Alpine mine ........................ _ ........... . 

34. Vertical section of vein in Dyer district _ . _ ... _. _ .... _ .... __ .. _. __ .. __ ..... __ .. _ . __ ... . 

35. Auriferous quartz lenses in alaskite, Windypah district ................................. . 

36. Cross section of Hector vein·, Windypah district .... _ .................. _ ....... _ ....... . 

37. Cross section of Chloride vein, Windypah district. ..... _ ............... _ ............... . 

38. Cross section at Widow prospect, Windypah district ........... _ ..... _ ................. . 

39. Forking of auriferous quartz lens, Drinkwater mine ....... _ ...... _ .. _ .................. . 

40. Intrusion of coal seam by glassy rhyolite ............................... __ ............ . 

"" j 

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OUTLINE OF REPORT. 

In the Silver Peak quadrangle there is a thick series of Paleozoic limestones, 

with slates and some impure quartzites, all belonging within the Cambrian and 

Ordovician periods. The detailed stratigraphy of these rocks is still in doubt. 

The Ordovician strata apparently overlie the Upper Cambrian conformably. No 

sedimentary rocks intermediate in age between the Ordovician and the probable 

Eocene have been found within the area of the quadrangle, but there are extensive 

and thick deposits belonging to the Tertiary. These consist of soft shale, sandstones, volcanic tuffs, etc., with interbedded layers of andesitic and rhyolitic lava, 

the thickness of the whole accumulation being very likely several thousand feet. 

Some of the beds are undoubtedly lake sediments, while others bear the marks of a 

dry, subaerial origin. It is probable that practically the whole Tertiary, from the 

Eocene through the Pliocene, is represented. These Tertiary deposits at Silver 

Peak are part of a larger belt which has been identified in the Tonopah district, in 

the Funeral Range, and elsewhere. This belt runs northwest and southeast in the 

region lying immediately east of the Sierra Nevada, and reaches at least as far 

north as northern Nevada and as far south as the Mojave Desert. Much of the 

·material in these beds was laid down in inclosed lake basins, and some of it 

during periods of aridity, as is indicated by chemically precipitated calcareous 

limestones, gypsiferous beds, beds of colemanite (borate of lime), etc. The belt of 

Tertiaries practically coincides with a belt in which borax is found in commercial 

quantity. 

Within the Silver Peak quadrangle are abundant granitic rocks, intrusive into 

the Paleozoic strata, especially in three chief areas-in the northeast corner, near 

Lone Mountain; on Mineral Ridge, near Silver Peak village, and in a long belt in the 

southern part of the quadrangle. In the first-named region the rocks are chiefly true 

granites, composed of alkali-feldspar and quartz, with some biotite and muscovite. 

These rocks often pass into slightly later aplitic types, consisting chiefly of quartz 

and alkali-feldspar, and so having the composition of alaskites. In Mineral Ridge 

the prevalent phase of the intrusive rock is alaskite, with frequent phases corresponding to the siliceous biotite-granite of Lone Mountain. The alaskite gradually 

passes by diminution of the feldspar into pure quartz "veins," which have very 

much the same chemical and genetic relation to the alaskite that the alaskite has 

to the granite. The granites in the southern part of the quadrangle vary in composition from alaskite to normal granite and to quartz monzonite, the proportions 

of lime, soda, and potash being variable. The various closely related phases of the 

9 
10 OUTLINE OF REPORT. 

granitic intrusions are regarded as derived from a single, general, granitic magma, 

and it is probable that the different areas represent practically a single period of 

intrusion. From the evidence in the Silver Peak quadrangle alone the age of this 

intrusion is determined only as post-Ordovician and pre-Tertiary, but from evidence 

derived from neighboring Nevada localities it appears probable that the intrusion 

is of the same age as the granitic rocks of the Sierra Nevada-namely, late Jurassic 

or early Cretaceous. 

Dikes of diorite, generally altered to greenstone, are abundant in the Silver Peak 

region. They are always younger than the granitic rocks, and also are younger 

than the aplites or alaskites. On Mineral Ridge they are younger than the quartz 

veins, which are the siliceous extreme of the alaskitic injection. On account of 

their association with the granitic areas, it is suggested, however, that the diorites 

may be a later manifestation of the granitic intrusions and may represent a magma 

complementary to the alaskites, the two representing the results of differentiation 

of a portion of the original granitic magma. 

In this region large quantities of lava were erupted during most of the Tertiary. 

Indeed, the volcanic activity continued into the Quaternary. The lavas consist 

of rhyolites, andesites, and basalts, with some dacites. 

The Pleistocene detrital deposits, which are abundant in this region, are not 

sharply divided from those of the late Tertiary. They are almost entirely subaerial. 

. The process of erosion is typical of this desert country and results in the formation 

at the foot of the mountains of broad aprons of drift, which pass down into flat 

detritus-covered valleys. In the lowest portion of each mountain valley there is a 

flat playa deposit, caused by sedimentation from the water which gathers there 

after occasional unusually great precipitation. Sand dunes accumulate in wind 

eddies in certain portions of the valleys. 

It is probable that the Nevada ranges, such as the Silver Peak Range, shared 

in the stresses which uplifted the Sierra Nevada at the close of the'Jurassic, but to a 

less degree. The Sierra Nevada experienced a greater uplift, resulting in the 

western Nevada province being transformed into an elevated trough. During the 

Cretaceous this depressed belt was one of erosion and free drainage. During the 

whole Tertiary and down to the present, lake basins were repeatedly formed and 

again altered or destroyed by new crustal disturbances accompanied by copious 

volcanic eruptions. It is probable that such disturbances were accompanied by 

some folding and faulting, resulting in local elevations and depressions, so it is 

probable that in this belt there are both mountains and valleys whose configuration 

is due primarily to deformation rather than to erosion. The rock structure of the 

Silver Peak Range is known to be complicated-to such an extent, indeed, that it 

has not been worked out. The presence of folds and faults is certain. Tertiary 

beds are in places arched up over tlie lower part of the Silver Peak Range, attesting 

flexing and faulting accompanying the uplift of the range in Tertiary time. It is 

not yet certain what the resulting balance has been in this region between the forces 

of erosion and deformation. The writer, however, regards it as probable that at 

least part of the surface configuration may be due to direct deformation. 

The Silver Peak, or Mineral Ridge, district is the oldest and most important of 

the several mining districts of the quadrangle. It contains abundant silver mines, 
OUTLINE OF REPORT. n 

as well as gold mines which have been considerably worked and are still regarded 

as of potential value. The silver deposits were discovered in 1864. The chief 

production has come from the gold ores, mainly from the mines of the Drinkwater 

group, which have been worked intermittently. Subsequent to thw discovery of 

Tonopah a number~£ prospects were located around Lone Mountain, some of which 

have proved valuable. Prospects on the west side of Silver Peak Range, 1 mile 

east of Dyer's ranch, in Fish Lake Valley, have been located several times, but have 

had no production. In the southwestern part of the quadrangle the Windypah, or 

Fesler, district is still in the prospecting stage. In the extreme southern part of 

the quadrangle, on the northern slopes of the Palmetto Mountains, are certain prospects which have had no production. The total production of Mineral Ridge is 

estimated at $1,418,000; the other mines and prospects of the quadrangle have not 

produced any considerable amount. One of the largest areas of sand dunes is 

reported to have yielded assays showing a considerable amount of gold throughout, 

and has been considered as a mining proposition, but it has not yet been proved 

that more than traces of gold are present. 

The typical auriferous quartz of the Mineral Ridge district is white and crystalline, and is in appearance and nature like that of the characteristic gold quartz found 

in so many districts in the world. It occurs in the form of overlapping lenses, 

intrusive into metamorphosed slaty limestones along a certain zone, and associated 

with similar lenses of alaskite. The quartz contains throughout gold and a little 

silver, the gold being principally in a free state, though some is contained in sulphides. 

Typical quartz and typical alaskite form two ends of a rock series between which 

every gradation is abundantly represented. As a rule, the gold grows rapidly less 

with incoming feldspar, although occasionally feldspar-bearing rocks carry good 

values. The alaskite is made up especially of quartz and feldspar, with some muscovite, the feldspar consisting of orthoclase, microcline, anorthoclase, albite, and 

oligoclase-albite. In the crystallization of the rock two distinct periods or generations of crystals are always represented. The chief lesson taught by a study of the 

crystallization is that the quartz is distinctly younger than the feldspar. The muscovite is generally in fine fibers and has formed at the expense of some of the feldspar, 

and on examination might be disposed of as secondary sericite, but this muscovite 

has formed only at the expense of the feldspars of the first generation, and it is clear 

that the partial alteration of the feldspar of the first generation took place when the 

magma was partially consolidated and before the deposition of the remainder, which 

formed the secon.d generation. Many observations show that the first generation of 

crystals was rigid enough to be partially cracked and fissured in place and that the 

residual fluid solidified as quartz in these fissures, as well as in the interstitial places 

between the crystals. Besides occurring in these forms, the quartz magma collected 

in larger masses, and by itself formed on a small scale an independent intrusive in 

nearly the same sense as the alaskitic magma had done. 

Some subsequent mineralization, later than the primary consolidation of the 

auriferous quartz magma, has been noted in certain mines of the district. In these 

mines the primary lenses have been cracked by subsequent movement, and the 

cracks, especially those near the hanging wall, have been ·filled with auriferous 

pyrite and galena. These ores, it is thought, have not been leached and concen-
12 OUTLINE OF REPORT. 

trated from the ores first deposited, but represent a later fresh supply brought in by 

ascending waters. It is believed that these solutions were not dependent in any way 

upon the diorite, which often follows the primary lenses and is always later than 

them; but it is believed that the mineralizing solutions were similar in composition 

to the primary solutions, though more aqueous and attenuated." 

Primary auriferous magmatic quartz, similar in origin to that of the Mineral 

Ridge district, has been found also in the Windypah district, in the southern part of 

the quadrangle, but has not been proved to be economically important. 

A special type of auriferous deposits in the Mineral Ridge district is represented 

by the Great Gulch mine. This is a deposit of auriferous arsenopyrite, which is 

believed to be similar in age and origin to the subsequent ores of the previously 

described gold mines. 

On the margins of the auriferous quartz district of Mineral Ridge are a number 

of mines and prospects containing more silver than gold. The general geology is 

like that of the gold-bearing ores. Alaskite and quartz lenses are intrusive into 

metamorphosed sediments and are accompanied by greenstone dikes. The ore, however, is subsequent and has formed along cracks in the primary quartz. The 

whole history indicated is analogous to those auriferous quartz mines of. the Mineral 

Ridge district which show notable subsequent mineralization, although the character of the ore in the silver mines is somewhat different, in that more silver and 

copper in proportion to the gold are present. Another type of silver-bearing veins 

has a gangue of contemporaneous quartz, and has formed by replacement of dolomite 

near the edge of the auriferous quartz district. 

In all these silver-bearing deposits the mineralization seems to differ from the 

subsequent mineralization of the auriferous quartz mines chiefly in the presence of 

more silver and copper, although otherwise the facts are not unfavorable for regarding all as belonging to the same period. The writer here advances the hypothesis 

that solutions of granitic origin have deposited in the granite, or in rocks silicified by 

the metamorphic effect of the granite, gold predominantly, and that in or near the 

calcareous or dolomitic intruded rocks more silver and copper were precipitated from 

the same solutions, the difference being due to the selective precipitative influence of 

the wall rocks. 

The veins of the Lone Mountain group of mines and prospects generally follow 

the stratification of sedimentary rocks, though more rarely they crosscut the formation. There is a strong likeness between the different ores of this district, which 

contain both gold and silver. The characteristic mineral is stetefeldtite. The chief 

gangue mineral is quartz, but there is usually some calcite, and in some types epidote, 

garnet, etc., are abundant. The general conclusion is that at the time of the intrusion of the granite mass in this district siliceous solutions emanated from the hardening mass, recrystallized and metamorphosed the intruded sediments, and deposited 

metalliferous veins along favorable channels. The genesis of these deposits is similar 

to that of certain of the silver-bearing deposits of the Mineral Ridge district. 

In the southern part of the quadrangle the prospects in the Dyer districtare 

identical in type with a certain class of the Lone Mountain district veins. The values are mostly silver and the predominating metallic mineral stetefeldtite. In the 

Windypah district, besides the type of prospects due directly to siliceous magmatic 
OUTLINE OF REPORT. 13 

segregation and similar to the Mineral Ridge type of auriferous quartz, there are 

several other forms of ore deposits. One of these consists of auriferous· quartz veins 

following shear zones in the granite. The resemblance of these veins in composition 

to the veins of magmatic quartz leads to the belief that they also are due to siliceous 

residual solutions, derived from consolidation of granite, but that they have formed 

in portions of the granite which have already consolidated. Both the above-named 

types occur in granite. A third type occurs in calcareous and argillaceous sediments 

near the granite contact, the country rock having been metamorphosed by the intrusion. The values here are chiefly in silver, with some gold, and among the metallic 

minerals stetefeldtite, as well as galena, chalcopyrite, etc., are prominent. 

In the Palmetto district the prospects belong to the different types enumerated 

for the Windypah district. 

An intimate interrelation has been recognized for all the metalliferous ores of the 

quadrangle, and all have been traced to the consequence of one event, namely, the 

intrusion of granitic rocks into Paleozoic sediments in probably post-Jurassic time. 

The ore deposits may be divided into two chief groups, (1) bodies of auriferous quartz 

which separated out in gelatinous form from alaskite during the process of crystallization and are of the same age and nature as the intergranular quartz of granite or 

alaskite; (2) quartz veins due to replacement or impregnation of original material 

along fracture zones by siliceous solutions more attenuated than those which 

deposited the ores of the first type and probably residual from the crystallization of 

the magmatic quartz of the first type. Deposits of the second group were formed 

chiefly in the intruded strata and to a less degree in the granites. They were contemporaneous with the contact metamorphism of the sediments. Such deposits 

contain relatively more gold when they occur in the granite and more silver and lead 

when they are in the intruded strata, and the gangue minerals also vary. The 

different character of the metallic minerals and gangue is believed to be due largely 

to the difference in wall rocks. In all the types of ore deposits the character of the 

solutions is believed to have been highly siliceous and alkaline, mineralizers such as 

fluorine and boron being present in a limited amount. 

The most interesting type of deposits in the quadrangle is represented by the 

lenses of magmatic quartz, a type which has not heretofore been fully recognized. 

The other types can be paralleled in other provinces of the world. 

Taking all the different types of deposits in the Silver Peak quadrangle as a 

whole, a number of similar examples present themselves in this same region. The ore 

deposits of the Belmont district and the southern Klondike are analogous to those of 

the Silver Peak region in respect to the nature of the veins, gangue, and wall rock. 

The auriferous quartz veins of the Sierra Nevada also present an analogy. The 

general conclusion is that the Silver Peak region is part of a larger province represented more abundantly in the Sierra Nevada of California and with only outlying 

smaller areas in adjacent portions of Nevada. All the ore deposits of this province 

owe their existence to the intrusion of the post-Jurassic granite, and it has been concluded that the ores were due to siliceous solutions which were the residue of the 

crystallization of the granitic rocks. 

In a previous report (Professional Paper U. S. Geol. Survey No. 42) the writer 

described the ore deposits of Tonopah, which lies not far east of the Silver Peak 
14 OUTLINE 01!' REPORT. 

quadrangle, as due to the action of magmatic waters and vapors following the 

eruption of certain Tertiary volcanic rocks. Analogies were pointed out between, 

Tonopah and other districts in Nevada, and the comparison was extended to Idaho 

on the north and Mexico on the south. The writer characterized the region in which 

these silver-gold veins occur in Miocene volcanics as a metallographic province. 

The interresemblance of the different ore deposits connected with the granitic 

intrusion in western Nevada is such as to justify rating this region from this standpoint as a metallographic province also. 

The conclusions drawn from the study of the Silver Peak region support a 

theory proposed by the writer in 1898 to explain the auriferous quartz veins of the 

Yukon district in Alaska. During the nineteenth century there has been considerable investigation concerning the nature of granite, pegmatite, and magmatic quartz 

veins, the results of which can be assembled to support the different steps of reasoning leading up to the conclusion referred to. It has been pointed out by Breislak, 

Fuch, Scheerer, and others that a granitic magma must contain a considerable 

amount of water and other mineralizers. One of the :final phases of granitic intrusions, pegmatites, has been investigated and discussed by a number of observers, 

many of whom have recognized the fact that quartz veins are in many cases a phase 

of the granitic intrusion and may even be considered as the consolidation product of 

an ultrasiliceous magma. Among the writers whose work has contributed support to 

this view are notably Lehmann and Howitt. The presence of metallic minerals in 

these pegmatites and in the associated quartz veins is common. Magnetite is in 

some places so abundant as almost to form an ore. Among the metals which have 

been described as occurring in pegmatite in sufficient quantity to be economically 

valuable are copper, tin, antimony, and molybdenum. The presence of gold in 

granites, pegmatites, and aplites has frequently been noted, and gold is very characteristic of those quartz veins which are closely related to pegmatites and are of 

magmatic origin. Numerous examples in different parts of the world are furnished 

of gold quartz veins intimately dependent upon granitic intrusions. 

Nonmetalliferous minerals also occur in the Silver Peak quadrangle. About 10 

miles north of Silver Peak there is a deposit of alum and sulphur in rhyolite. This 

deposit is probably the result of fumarolic activity. The several playas within the 

quadrangle contain incrustations of common salt and borates of lime and soda. 

The borax industry is dormant at present, but has been of considerable importance. 

As regards the genesis of the deposits of salt in the playas, it was once held that they 

had been leached out from the disintegrated granites and other ordinary rocks of the 

drainage areas; but beds of borate of lime have been discovered in the early Tertiary 

sediments, and it is evident that a large part of the borates in playas in this region 

has been derived from leaching of the Tertiary deposits. Within the Silver Peak 

quadrangle the character of the salts is different in the different playas, although the 

rocks in the drainage areas are practically the same. Moreover, it is plain that the 

larger part of the salts is derived from hot springs which emerge in these valleys. 

The different character of the deposits in the playas therefore seems to depend largely 

upon the different nature of the springs. 

Boron is one of the rarer elements, and its concentration into abundant deposits 

implies some active process of concentration. It occurs principally either in deposits 
OUTLINE OF REPORT. 15 

from dry lakes or in deposits from volcanic fumaroles. Under the latter condition it 

appears in commercial quantities in Italy. On the Pacific coast of the United States 

there are several localities where hot springs containing borax and boracic acid seem 

to be dependent upon comparatively recent volcanic action. This suggests that the 

borax obtained by evaporation of dry lakes in this region may ultimately have been 

derived from volcanic fumaroles, since the Tertiary sediments which contain colemanite were formed during a long period of active volcanism. 

Coal occurs in the Tertiary sediments at the north end of the Silver Peak Range. 

The chief seams are four in number. The coal is o£ rather poor quality, containing a 

good deal o£ ash. However, it might possibly be used as a gas coal. 

ORE DEPOSITS OF THE SILVER PEAK QUADRANGLE, 

NEVADA. 

By J. E. SPURR. 

CHAPTER I. 

GENEHAL GEOLOGY. 

STRATIFIED ROCKS. 

CAMBRIAN-ORDOVICIAN STRATA. 

Paleozoic limestones, with slates and some quartzites, are well represented in 

the area of the Silver Peak quadrangle (Pl. I). They belong entirely within the 

Cambrian and Ordovician periods. Fossils obtained by Mr. J. E. Clayton as early 

as 1866, at Silver Peak, and first regarded as Silurian or Devonian, were shown by 

Mr. Walcott to be Cambrian.a Some parts of the Cambrian limestone contain 

masses of the same corals that are foun'd in the range lying next west (the White 

Mountains), so that Mr. Walcott regarded the two occurrences as essentially forming part of a single reef.b 

From the Clayton collection of fossils Mr. Walcott identified the following:a 

Archreocyathus atlanticus. 

Archreocyathus undet. 

Ethmopbyllum whitneyi. 

Strephochetus i sp. 1 

Kutorgina (hkc K. ringulata). 

HJohthes princeps. 

O!enellus g!lberti. 

Most of our knowledge of tL0 Paleozoic strata is derived from the detailed 

work of Mr. H. W. Turner. The writer and Mr. F. B. Weeks have also collected 

fossils at various places within the district under discussion. The known fossils 

show the presence of strata belonging to the Lower Cambrian, the Upper Cambrian, 

and the Ordovician. The rocks, however, are characteristically considerably 

folded and faulted, and frequently metamorphosed; and the series, which is several 

thousand feet thick, pres(lnts in its difierent parts no very striking and constant 

lithologic differences. The detailed stratigraphy and structure, therefore, are still 

a Bull. U. S. Geol. Survey No. 30, p. 38. bAm. Jour. Sci., 3d ser., vol. 49, p. 144. 

13002-No. 55-06-2 17 
18 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

in doubt, and partly for this reason the Cambrian-Silurian rocks are represented 

together on the accompanying geologic map. 

The following notes are derived from the work of Mr. Turner: a 

Lower Cambrian rocks are found in the southeast portion of the quadrangle. 

Here are mica-slates, quartzites, and limestones, containing Olenellus, Arch::eocyathus, and probably Salterella. In the hills north of Clayton Valley, in the northeast part of the quadrangle, the Cambrian shows a thickness of several thousand 

feet of dolomitic limestone and marble, quartzites, and green knotted schists 

beneath the lowest fossiliferous horizon, which is a limestone carrying Arch::eocyathus. Overlying this come slates containing Ethmophyllum and Olenellus. 

In Mineral Ridge, west and northwest of Silver Peak, there is a lower series of 

considerwble thickness, consisting of limestone and slates, with some dolomitic 

marble beds. This series has been intruded by numerous alaskitic sheets and by 

quartz veins, so that is has become largely schistose and gneissic. b This formation 

is overlain by massive dolomitic limestones and quartzites, and these are overlain, 

as Mr. Turner has shown, by Olenellus slates and dark limestone carrying Lower 

Cambrian fossils. The Olenellus slates and limestone are exposed, among other 

places, in Alcatraz and Goat "islands," near Silver Peak village. 

Analyses of the Lower Cambrian carbonate rocks made for Mr. Turner by Mr. 

George Steiger show both dolomite and limestone, as well as types of intermediate 

composition. 

Analy8es of Lower Cambrian carbonate roclrs. 

1. 1 2. 1 3. ! 4. -·-·--]-

Lime (CaO).----------·---------------- -------------·--.--------------------------- ~8 :~ 21 0:~ 51 ~:.·.~9 , 52 .. 00

Magnesia (MgO) ............. _ ....... _ .... _. _ ........ - ... _.-- ............. -- ...... - I 42 

Ferrous oxide (FeO)a .......... ----------------- ....... -------- ...... ------- .95 'I 1.89\. ---- ----------

Carbondioxrde (CO,) --------~---------------- ---------------- _ 44.09, 47.21 ......... "1" ........ . Insoluble in borlmg hydrochlonc acrd .. -...... ---- ... ---------------- ·-------------- 7.181 .31 ------- --'----------

_____ _ 99.93 99.9~r:--:-:-:-:-:-::-:[:-:~-:-:-:-: -------

a Includes any alumina, phosphorus, or titaniurn that rnay be present. 

Of these analyses Nos. 1 and 2 are true dolomites, No.3 is a dolomitic limestone 

or marble, and No. 4 is a limestone. No. 1 is from the basal dolomite in the hills 

north of Clayton Valley, Nos. 2 and 3 are marbles from Mineral Ridge, while the 

exact locality of No. 4 is not given by Mr. Turner. 

Upper Cambrian fossils have been found at several places in the quadrangle, 

as, for example, in the hills 4 miles east of Silver Peak village, and also in the north 

part of the Silver Peak range, 4 miles northeast of the mill of the Pacific Borax 

Company. In slates and thin-bedded limestones at these localities are linguloids; 

trilobites (Acrotreta), fragments of Phyllocarida, and sm:p.e corals are found. Mr. 

Walcott regards this fauna as Upper Cambrian. 

Ordovician strata overlie the Upper Cambrian in apparent conformity in such 

a way as to suggest continuous deposition between the two periods. The Ordovician 

a The determinations of fossils were made for Mr. Turner by Mr. C. D. Walcott. 

b The interpretatiOn of this formation is the writer's. (J. E. S.) 
STRATIFIED ROCKS. 19 

rocks contain graptolites, especially in the neighborhood of Emigrant Pass. Mr. 

Charles Schuchert found that most of these graptolites belong to the Normanskill 

or lower Trenton horizon of the Ordovician, while the Quebec horizon was represented by two characteristic genera, Didymograptus and Tetragraptus. 

TERTIARY STRATA. 

No sedimentary rocks intermediate in age between the Ordovician and the 

probable Eocene have been found within the area of the quadrangle, but there are 

extensive and thick deposits belonging to the Tertiary. These Tertiary deposits 

flank the edges of the mountains and underlie, in part at least, the Pleistocene 

veneer of the valleys. On account of folding and faulting since their deposition 

they arch upward along the sides of the mountains, although according to Mr. 

Turner they have not been found within 2,500 feet of the highest elevations. They 

consist of soft shales, sandstones, marls, tuffs, volcanic breccias, etc., with interbedded layers of andesitic and rhyolitic lava. The thickness of the whole accumulation is very likely several thousand feet. This mass has not yet been satisfactorily 

differentiated into separate members, but it undoubtedly contains materials deposited under widely varying conditions. Some of the beds are lake sediments; some 

appear to have been deposited in running water and were probably distributed by 

stream action. Others bear the marks of dry, subaerial origin. Also there is 

probably a great range in the period of deposition, as will be presently shown from 

a consideration of the fossil evidence. It is probable that practically the whole 

Tertiary, from the Eocene through the Pliocene, is represented. In short, it is 

probable that the beds are the record of the whole period of Tertiary sedimentation, 

beginning with the period when the Nevada land mass ceased to have free drainage 

to the ocean, at the close of the Cretaceous,a through the whole of the climatically 

changing but in general arid Tertiary period, when the material eroded from the 

mountains was accumulated in the valleys, in lakes, or in subaerial sheets, down 

through the Pliocene. Both the early and the more recent Pleistocene accumulations of the region are of very much the same nature as many of these Tertiary beds, 

and probably form a direct continuation of them; but in the Pleistocene material the 

proportion of lake beds does not appear to be nearly so large as in the Tertiary 

formations. b 

This post-Cretaceous period, characterized by lack of external drainage, was 

also characterized by enormous volcanic activity.c Indeed, the writer looks with 

favor upon the hypothesis that the crustal basins, without external drainage, which 

held the Tertiary lakes of this region, were directly due to volcanic action, usually 

to a sinking or collapse after a period of active eruptions, just as the regional elevations with which the depressions alternated were due to the accumulation of volcanic 

material beneath. These Tertiary beds are made up largely of volcanic tuffs and 

breccias derived directly from eruptions, or of detritus removed by erosion from volcanic rocks; and there are numerous intercalated layers of solid lava, locally increasing 

in volume till the whole nature and process of sedimentation becomes obscured. 

a Spurr, J. E., Origin and structure of the Basin ranges: Bull. Geol. Soc. America, vol.12, p. 249. 

b Op. cit., p. 251. 

cOp. cit., p. 249. 
~0 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

The Tertiaries at Silver Peak contain remains of fresh-water mollusks, fish, and 

plants, as well as coal beds. In 1897 Mr. S. A. Knapp a collected some fossils from 

near the coal beds at the north end of the Silver Peak Range, which Dr. J. C. Merriam, of the University of California, considered indicative of fresh-water origin, and 

possibly .Miocene. In 1899 the present writer collected some poorly preserved shells 

from Tertiary beds, containing a large amount of detrital or tuffaceous andesitic 

material, about 10 miles southeast of Columbus, not far from the locality mentioned 

above. Dr. W. H. Dall thought these probably fresh-water fossils. He found a 

bivalve which may be a Sphcerium and a gasteropod that m!ly be a Planorbis. Farther northeast in the s:1me series the writer found at one locality very abundant 

silicified wood. Mr. H. W. Turner also in 1899 collected shells and leaf remains 

from near the coal beds. b In the shell collection Dr .• T. C. Merriam found Oampeloma 

sp., Unio sp., Planorbis like spectabilis .Meek, and Ancylus like undulatus .Meek. 

Doctor Merriam remarked that the first three forms resemble species described from 

the Eocene of the western United States, and the last form a snccies described from 

supposed Miocene beds. He suggested that the beds from which the collection came 

might be early Miocene or late Eocene. Mr. F. H. Knowlton found that the fossil 

leaves represented mostly new species, many of them resembling living forms. One 

species, Salix angusta, is found in the Green River group (Eocene) and in the European Miocene; another, a Oinchonidittm ( ?) is allied to a form in the Fort Union 

group (Eocene?). Higher in the series Mr. Turner collected fish remains which 

Prof. F. A. Lucas referred to a single species of Leuciscus, not differing greatly from 

living forms. c Thus the evidence presented by the fossils found in the Silver Peak 

quadrangle is not very definite, indicating only the likelihood that the beds may range 

in age between Eocene and Pliocene. 

About 10 or 15 miles east of the Tertiary deposits in the northeastern part of the 

Silver Peak quadrangle, near the mining camp of Ray, simil:1r Tertiaries, consisting 

of folded gravels, tuffs, lavas, and some white, thin-bedded, fossiliferous limestones 

are found. Beds of similar appearance outcrop at intervals between this place and 

the Silver Peak area. The fossils from the above-mentioned limestones collected by 

the writer were referred by Dr. vV. H. Dall to the Wasatch or Bear River Laramie 

(Eocene), nearly equivalent in age to the marine Lower Eocene of the southeastern 

coastal plain. Doctor Dall identified Vivipara couesi ?, Planorbis utahensis Meek, 

Ancylus? sp., Oorbicula ? occidentalis? Meek (possibly Sphcerium idahoense Meek). a 

Eight miles south of this locality, in the Tonopah mining district, is a series of 

Tertiary lavas similar to those associated with the Tertiary sediments at Silver Peak.e 

There is also at Tonopah, associated with the lavas, a thick series of stratif;ied lake 

beds, consisting mostly of rhyolitic tuffaceous material and containing infusoria. 

These lake beds the writer has provisionally correlated with beds of the Truckee 

group, described by the geologists of the Fortieth Parallel Survey, and found farther 

north in this region, especially in the Kawsoh Mountains/ These deposits were 

a Mining and Scientific Press, San Francisco, vol. 74, 1897, p. 133. 

bAm. Geologist, vol. 25, p. 168; Twenty-first Ann. Rept. U.S. Geol Survey, pt. 2, pp. 192-224. 

c Fossil fish were collected from this locality or near it, as noted by W. P. Blake in Proc. Cal. A cad. Sci., vol. 3, 1866, p. 306, 

but there is no record of their identification. 

d Spurr, J. E., Geology of the Tonopah Mining District, Nevada: Prof. Paper U.S. Geol. Survey, No. 42, pp. 66-67. 

• Spurr, J. E., ibid., p. 31 et seq. 

f U.S. Geol. Explor. 40th Par., vol. 1, p. 412 et seq. 
STRATIFIED ROCKS. 21 

referred by King to the Miocene chiefly on the basis of a correlation made by him 

between them and the John Day beds of Oregon, still farther north, which contain 

vertebrate remains classed by Professor Marsh as clearly Miocene. a The whole series 

of volcanics at Tonopah were, according to the determinations of the writer, erupted 

during the Miocene and Pliocene periods. 

Farther south, in the Funeral Range, at Furnace Creek, the writer observed 

upturned Tertiary strata resembling those at Silver Peak. b The series is several 

thousand feet thick and rests unconformably upon Paleozoic limestones. The beds 

are conglomerates, clays, sandstones, and chemically precipitated limestones or 

travertine, which also occurs in the Tertiaries at Silver Peak. The Furnace Creek 

beds are often gypsiferous, contain grass remains, and include also a bed of borate of 

lime, or colemanite. No fossils have as yet been found in them. These Tertiaries 

extend southward and are widely distributed. In and near the El Paso Range Mr. 

H. W. Fairbanks" has described a series of tilted clays, sandstones, volcanic tuffs, 

and interbedded Ia vas. This series is at least 1,000 feet thick. A seam of coal 

occurs in these beds, near which are found fossil leaves which Doctor Knowlton 

regarded as probably Eocene. Farther south, in the Mojave Desert, near Daggett, is 

a folded and faulted series of sandstones, shales, and tuffs more than 1,000 feet thick. 

The series overlies rhyolite and contains a bed of colemanite. Mr. W. H. Storms 

who has described this occurrence,d regards the period of folding as perhaps Oligocene. 

From these observations it appears that a broad belt of Tertiary sediments, generally folded and faulted, runs northwest and southeast in the region lying immediately east of the Sierra Nevada, and reaches at least as far north as northern Nevada 

and as far south as the Mojave Desert. These beds consist of a variety of sediments, 

but wherever encountered contain much volcanic material in the form of pumice, 

tuffs, and intercalated lava sheets, showing vigorous rhyolite and andesite eruptions 

during the period of accumulation. Much of the material was laid down in inclosed 

lake basins, and some of it at least during periods of aridity like that existing at present, as is indicated by chemically precipitated calcareous limestone, gypseous beds, 

colemanite (borate of lime) beds, etc. The belt of Tertiaries which we are describing 

practically coincicles with a belt in which borates are found in commercial quantities. 

The best deposits are interbedded layers in the Tertiaries, but the recent accumulations in the valley "alkali flats" or playas, due to the evaporation of the drainage 

waters, furnish some workable deposits. Inasmuch as the playa borax region, however, is associated with the upturned Tertiaries and does not occur under similar 

topographic and climatic conditions in the country to the east of this belt, it is probable that the material is often leached from the earlier beds, even in localities where 

these do not show it. 

a Op. cit., p. 423. 

b Dull. U. 8. Geol. Survey No. 208, p. 189. 

cAm. Geologtst, vol. li, Feb. 1896, p, 67. 

d Geology ol San Bernardino County: Eleventh Ann. Rept. Cal. State Min. Bureau, 1892, p. 337. 
f 

22 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

IGNEOUS ROCKS. 

PRE-TERTIARY. 

GRANITIC ROCKS. 

Granitic rocks, intrusive into the Paleozoic strata, are well represented in the 

quadrangle, espeCially m three chief areas-in the northeast corner, near Lone Mountam (whlch Is just north of the northeast corner and is itself composed mainly of 

granite); on Mineral Ridge, near Silver Peak village, and m a long belt running 

northwestward across the southern part of the quadrangle. 

In the first-named region (near Lone Mountain) Mr. H. W. Turner has found 

that the granitic rocks are chie~y true gramtes, composed of alkah feldspar and 

quartz, with some bwtite and muscovite The feldspar mdudes orthoclase, microcline, and albite, with micropegmatitic and microperthiticmtergrowths. 1, Thegramte 

of the south base of Lone Mountam, near the edge of the quadrangle, was determined 

by Mr Turner to contam feldspar, quartz, biotite, iron oxidi, titanite, and apatrte, 

the feldspars compnsmg orthoclase, miCrochne, and oligoclase Zircon also was found 

by the wnter in tlns Lone Mountain gramte. The rock of the gramte area, 6 miles 

in dramcter, lying south of the Lone Mountam gramte, has, according to Mr. Turner, 

practically the same composition, though its structure IS often porphyrittc, or even 

gnerssic. The granitic rocks of this region often pass into or are cu.t by shghtly later 

aphtiC types consisting chie~y of quartz and alkali feldspar, and so haVIng the composition of alaskites. , , 

In Mmeral Ridge the mterbedded slates and thm limestones have been thoroughly injected by siliceous gramtw rock, mamly along the planes of stratificatiOn, 

formmg chrefly interbedded more or less lenticular bodies, and often penetrating the 

intruded rock mmutely and altermg 1t to a sclustose or gneiSSic condrtion. The 

prevalent phase of the intrusrve rock is alaskJte, or quartz-alkali-feldspar rock, 

having a granular texture (hke that typical of gramte), whtch very frequently becomes 

coarser or finer (pegmati tic or ap)ItiC). A frequent, but not common, phase of this 

alaskite IS a siliCeous biotite-gramte hke that at Lone Mountam. On the other 

hand, the alaskite pass~s by gradual transitiOns, by a diminution of the feldspar, mto 

pure quartz (in veins), which has very much the same chemical and genetiC relatwn to 

the alaskite that the alask1te has to the gramte The pure or nearly pure quartz 

phase of th1s siliceous injectiOn is much more abundant than the granitic type, 

while the mtermediate or alaskite type IS most wrdespread. 

The alaskite consists almost wholly of quartz and feldspar, the species of the 

latter havmg been determmed as orthoclase, microcline, and oligoclase-albite, with 

occasional muscovite, accessory z1rcon, and onginal pyrrte The alaskite sometimes 

has an anginal slight parallel or gneiSSic structure, as also does Its gramtic phase. 

The granite contains the same mmerals as the alaskite, with the additiOn of generally 

sparse bwttte and more muscov1te than the alaskites in general Sphene, magnetite 

(ilmenite~), pyrite, apatite, and tourmaline were also noted among the accessories. 

A specimen of the granitic phase from the lower tunnel of the Mary mme was 

collected by Mr. H. W Turner and analyzed by Mr. George Stmger, showmg the 

following partial composrtion: 
IGNEOUS ROCKS. 23 

Partial analyse.~ of granite from the Mary mine. 

Silica (SiO,) •.......................... _ ............ __ ................. ___ ............................................... 72.72 

Lime (CaO) .............................. _ ...................... _. _ ... _. ............................................. .. . .51 

Soda (Na,O) ............................................................ _ .............................................. _ 1.65 

Potash (K,O) ............................................................. _ .. __ ........................................ _ 6.93 

This speci~en was an uncrushed light-gray granite, composed of quartz, orthoclase, 

microcline, oligoclase, biotite, muscovite, zircon, and apatite. 

The granitic masses mapped by Mr. Turner in the southern part of the quadrangle 

contain a variety of different phases. In texture some are like ordinary granite, 

while some are porphyritic. Areas occur where the feldspar (orthoclase) phenocrysts of the porphyritic variety become an inch or more in length. Finer-grained 

porphyritic varieties also occur. In composition the rock varies from a normal 

granite to alaskite on the one hand and quartz monzonite on the other, the proportions 

of lime, potash, and soda being variable. Aplitic dikes and masses, often of considerable size, and ordinarily of alaskitic composition, are common. They lie frequently 

in the granite, and are evidently of slightly later consolidation, though having a 

common origin with it. These dikes and masses are especially abundant near the 

contact of the granitic masses, and occur in the neighborhood of the granite, in the 

usually more or less metamorphosed Paleozoic strata into which the granite is 

intrusive. 

Specimens of the granite from this region, examined microscopically by the 

writer, are made up of quartz, orthoclase, oligoclase, microperthite, and biotite, with 

sphene, apatite, and ilmenite. Mr. Turner found also pyroxene in the rock represented by the second analysis given below. These analyses of different types from 

the granitic rocks in the southern part of the quadrangle were made for Mr. Turner 

by Mr. George Steiger. They are arranged according to silica content. 

Analyses of granite rock8from southern part of Silver Peale quadrangle. 

------------------------·--~-- -- - ---;-------;------;-----

1. 2. 3. 4. 5. 

----------------------- ~-- ---~-----~--

Silica (SiO,)............................................................... 68.50 69.23 

Lime (CaO)............................................................... .60 3.38 

Soda (Na,O).............................................................. 4.05 3.75 

Potash (K,O)............................................................. 4.83 4.75 

71.14 

2.56 

3.65 

3.37 

73.22 

!.52 

2.79 

5.35 

76.04 

.46 

7.58 

.07 

No. 1 comes from about 6 miles south of Pipers Peak; No.2 is from the Palmetto 

Mountains, 6 miles southwest of Barrel Springs; No.3 is from 13 miles southwest of 

Pipers Peak; Nos. 4 and 5 are from about 5 miles southwest of Barrel Springs. 

These analyses indicate a considerable range in the composition, the rocks varying 

from a basic phase having the composition of a quartz-monzonite or granodiorite 

through the ordinary granite type to alaskite (No.5). 

APLITIC ROCKS. 

In all the areas in the quadrangle where granitic rocks occur, as mentioned 

above, there are related rocks of more siliceous composition, which clearly represent 

the later or aplitic facies of the intrusions. These rocks have most frequently a dense, 
24 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

rather fine-grained texture, while often their structure is like that of granite. Pegmatitic phases occur, and are especially abundant in Mineral Ridge, near Silver Peak. 

This more siliceous aplitic phase of the granitic intrusion is best represented near 

Silver Peak, where it forms most of the injected material, very little true granite 

being found there. In the granitic region in the southern half of the quadrangle, 

also, there is an abundance of the aplitic facies, here mostly of the fine-grained type, 

though pegmatites are by no means uncommon; but here, as also in the southern 

part of the quadrangle, the aplitic rocks are greatly subordinate in amount to the 

more normal granitic type of the intrusion. They occur as dikes in the granite, and 

to a much greater extent in the neighboring intruded rocks. 

The chemical and mineral compo;;;ition of the aplitic rocks, so far as examined 

by the writer, is similar over all the quadrangle. They are quartz-alkali-feldspar 

rocks, or alaskites, more siliceous than the related granites. The feldspars consist 

mainly of orthoclase, microcline, albite, oligoclase-albite, and anorthoclase. Accessory minerals are frequent muscovite, biotite (sometimes becoming common), 

sphene, zircon, magnetite, and pyrite. The chemical composition varies considerably, as will be seen from the following partial analyses of specimens collected by the 

writer from the lower tunnel of the Drinkwater mine on Mineral Ridge, and examined 

by Mr. George Steiger: 

Ann lyses of aplitic rocks from the Drinkwater mine. 

----~-------------------c--------;----;-----;------:----

1. 2. 3. 4, 5. 

·----------~--------~·----- ------------

Silica (SiO,) ... .. . . .. . .. .. .. ..... ... .. .. .. .. . . . . . . .. . . . .. . . . . .. .. . .. . . . . .. . 66.45 

Soda (Na,O).............................................................. 1.92 

Potash (KzO)................ ... ... .. ..... . . . . . .. ... . . .. . . . . . . . .. . . .. . .... 10.66 

71.92 

1.41 

9.17 

75.23 78.83 

2.72 1.03 

3.88 I 6.61 I 

----------------------~--~--~--~ 

80.63 

.27 

5.28 

No. 1 has a medium granitic texture, and the microscope shows quartz and 

microcline, with rare muscovite and frequent tiny zircons. No. 2 has a texture 

similar to that of No. 1, and consists of quartz, microcline, orthoclase, and an undetermined striated feldspar. No. 3 is rather fine-grained, with an original banded 

or gneisflic structure; it consists of quartz, orthoclase, microcline, and anorthoclase, 

with a little muscovite, and occasional original pyrite. No.4 has a medium-grained, 

granular texture, and consists of quartz, microeline, and probable albite. No. 5 is 

medium grained and granular, and consists of quartz, microcline, a little muscovite, 

and frequent zircon. 

In many phases of these alaskitic rocks a tendency is seen under the microscope 

for the different minerals-meaning essentially feldspar and quartz-to segregate 

into bunches, irregular in form or more frequently elongated, producing original 

gneissoid structure. These segregations increase in size till they are conspicuous to 

the naked eye, and by further enlargement quartz veins, often feldspathic, are formed. 

Such granitic and magmatic quartz is found in all the granite areas, but in the 

siliceous alaskitic area of Mineral Ridge occurs in great quantities, in thick veins or 

lenses. 
IGNEOUS ROOKS. 25 

AGE OF GRANITIC AND APLITIC ROOKS. 

The various closely related phases of the granitic intrusives are regarded as 

variations from a single general granitic magma. No well-marked boundaries 

between the different phases of the main granitic intrusions have been observed, 

and the slightly later age of the aplitic rocks is according to the well-known law 

governing the consolidation of granitic magmas-that the normal type is followed 

by more siliceous phases, representing the closing stages of magmatic consolidation. 

It is probable also that the different areas represent, essentially, a single period o£ 

intrusion. 

So far as the evidence in the Silver Peak quadrangle alone goes, we know only 

that the granitic intrusion was subsequent to the deposition of the Paleozoic strata 

and previous to that of the Tertiary sediments and lavas. The granitic rocks 

intrude Cambrian sediments in the northern part of the quadrangle and Ordovician 

and Cambrian in the southern part. Therefore their age is post-Ordovician and 

pre-Tertiary. 

In the Pilot and the Excelsior ranges, a short distance north of the Silver Peak 

quadrangle, there are granitic rocks similar to those at Silver Peak.a Here they are 

probably intrusive in Triassic and Jurassic strata. Still farther north. in the 

Ellsworth Range, n similar granitic intrusives penetrate formations which the writer 

has provisionally referred to the Triassic. Some of these intrusive rocks are characterized by unusually large orthoclase phenocrysts, like the type above referred to 

in the southern part of the Silver Peak quadrangle. North of this area, in the 

Star Peak Range, are granitic rocks (accompanied by alaskite dikes) which are 

intrusive into Triassic and probably Jurassic strata.' Similar granitic rocks occur 

also in neighboring mountain ranges, and are in many cases known to be intrusive 

!nto Paleozoic strata. d At Belmont dikes intrusive into Silurian strata consist in 

part of coarse granite-porphyry, with very large feldspar phenocrysts, identical in 

appearance with the coarse porphyritic phases in the Ellsworth and Silver Peak 

ranges. 

The work of Mr. H. W. Turner has shown that the granitic rocks in the southern 

part of the Silver Peak Range cross Fish Lake Valley, which lies west of the range, 

and are repr<:)sented in the White ~fountain Range. Granitic rocks are well rep~esented in this range (even more than in the Silver Peak Range) and in portions 

at least are known to cut Cambrian strata. The White Mountain Range is separated 

from the Sierra Nevada by Owens Valley. This adjacent portion of the Sierra 

Nevada is made up almost wholly of granitic rocks, and the simliar granitic masses 

of the t'Yo ranges are separated only by patches of Tertiary volcanics or by the 

detritus flooring the intervening valley. In the Sierra Nevada these rocks consist 

mainly of granodiorite and gramte, and the date of their intrusion has been fixed by 

studying the age of the intruded strata as in the epoch which included the close of 

the Jurassic and the beginning of the Cretaceous periods. 

a Spurr, J. E., Bull. 0. S. Geol. Survey No. 208, 2d ed., pp. 103, 109, and geologic map. 

b Op. cit., p. 102. 

c Louderback, G. D., Bull. Gcol. Soc. Arnenca, vol. 15, pp. 318, 336. 

d Spurr, J. E., op. cit., pp. 92, 95. 
2o ORE DEPOSITtl OF' SILVER PEAK QUADRANGLE, NEVADA. 

In the various granitic areas outside of the Silver Peak quadrangle, which the 

writer has enumerated above, aplitic rocks, chiefly of alaskitic composition, are 

abundant as a later phase of the consolidation of the magma. 

It appears probable, therefore, that the granitic rocks of the Silver Peak quadrangle and of various other ranges of western Nevada are similar in general nature 

and origin to the granitic rocks of the Sierra Nevada, and, like them, are of late 

Jurassic or early Cretaceous age. 

DIORITIC ROCKS. 

Dikes of diorite, usually not many feet wide, are abundant in the Silver Peak 

region. They are almost always more or less altered, sometimes completely. In 

their fresh form they consist, essentially, of feldspar and hornblende in varying 

proportions. By alteration they become a mass of secondary products, though 

the original structure may usually be distinguished. They are thus conveniently 

designated by the field name of greenstone. 

In dikes of this sort on Mineral Ridge Mr. H. vV. Turner has determined the 

primary feldspar as andesine and labradorite, and has noted as accessories apatite 

and ilmenite. Dikes of s1milar character, sometimes comparatively fresh, occur in 

the northeast corner of the quadrangle. In some of these Mr. Turner noted pyroxene 

and biotite. Certain dioritic areas in this vicinity, somewhat larger than the usual 

dikes, contain quartz in places, forming a quartz-diorite phase. 

The alteration processes to which the diorites have usually been subjected 

have produced as secondary minerals chlorite, quartz, calcite, zeolites, epidote, 

zoisite, kaolin, talc, etc. Fine secondary biotite was observed, together with other 

alteration products, in one specimen from the southern part of the quadrangle. 

Two partial analyses of greenstone from d kes from Minera' Ridge were made 

by Mr. George Steiger for Mr. H. W. Turner, as follows: 

Partial analyses of greenstone. 

1. 2. 

-----

Silica (SiO,) ................................................................................................ . 48.67 46.28 

Magnesia (MgO) ........................................................................................... . 8.75 19.54 

Lime (CaO) .•.•.... --····· __ ....... ____ ..... ____ ---· _______ ... ______ ·····--··· .... ___ .... ____ . ______ .... ____ . 8.58 9.91 

Soda (Na,O) ......... _. __ ........... ·- __ ...... ___ ······- ____ .. ···----· ...... -······- __ .... ____ -····--- .... __ _ J.39 2.21 

Potash (K,O) ...... ___ ...... ____ ... ··-- _ .... _____ ... _______ . __ .. ______ ····-- ____ .. ____ .... ______ .. __ --··· ··- _ .99 1.89 

No. 1 is composed chiefly of hornblende and altered feldspar; No. 2 chiefly of 

hornblende. Both rocks are less siliceous than ordinary diorites. 

The dioritic rocks appear from Mr. Turner's mapping to be associated with the 

areas of intrusive granitic rocks, being found especially in or near these rocks in 

much the same relationship (as regards location) that has been indicated for the 

aplitic rocks. In point of age the dioritic rocks are always younger than the granitic 

rocks, which they frequently cut. Where they are associated with the aplitic rocks 

(alaskites) they are also younger than these; and, as Mr. Turner has found, they are 

younger than the quartz vems of Mineral Ridge, which the writer has determined 
U. S. GEOlOGICAL SURVEY PROFESSIOIIIAL PAPER NO. 55 PL. II 

A. RECEN T BASA LTIC CONE NEAR S ILVER PEAK. 

View from the southwest. 

B. MILL AT SILVER PEAK. 
IGNEOUS ROCKS. 

. . . . . . .. .. . ,··· :·· .. · .. : :·· .. ··· :.··· ..... : ••• :~· •! •••••• ~ •••• •e• •••"•• •••••• •.• • ·~•• ••J• 

... . . (\ .. . . .. . . . . . . . . . . . . . .. : : : ·. .. .. :. ·: •• fl • .. • • • ••• • 

. . . . . .. . ... . . . . . . . .. . .. . . ... . . . . .. . . : .. ::.::·.:··.:·.: 

27 

to be the siliceous extreme of the alaskitic injection. Following the lines of least 

resistance, they often·run along one side of such a quartz vein. The greenstone 

dikes of Mineral Ridge, like the granitic-alaskitic dikes, are chiefly present in the 

altered thin-bedded limestone and slate formation which has been described (p. 18) 

as having been thoroughly injected and altered by the alaskitic materials; but 

both the granite-alaskites and the greenstones have not infrequently found their 

way up into the overlying formation, which is a massive dolomite. At one locality, 

near the Vanderbilt mine, the writer has observed the same dikes passing from the 

underlying schistose series to the overlying dolomite. 

These greenstone dikes are probably older than the Tertiary rocks, since they 

are not found in thei:n. Therefore the only direct evidence of their age is that they 

are post-Ordovician and pre-Tertiary. The apparent association with the granitic 

areas and the limited quantities of the diorite, which approximates in habit and 

amount the aplitic (alaskitic) intrusions, suggest, however, that the dioritic rocks 

also may be a later manifestation of the granitic intrusions. Viewed in this light, 

the diorites may represent a magma complementary to the alaskites, and the two 

may represent the result of differentiation of a portion of the original granitic magma 

which took place after the first intrusion and consolidation but before the consolidation of the more slowly cooling portions. A view similar to this has been taken 

by Mr. Waldemar Lindgren as to the origin of the dioritie rocks in a portion of the 

Sierra Nevada. a 

TERTIARY AND QUATERNARY LAVAS. 

In the area under consideration lavas were erupted in large quantity during 

most of the Tertiary. This period of eruption comprised volcanic activities covering 

the whole of this Nevada province, which itself is probably only part of a much 

larger province.b As is the case with the Nevada province in general, the volcanic 

activity near Silver Peak continued into the Quaternary. Indeed, the last outbreaks, 

though slight, occurred in comparatively recent time, as is shown by a small cone of 

fresh basaltic material (cinders and lapilli), with a crater-like depression in the top, 

near the village of Silver Peak. (Pl. II, A.) This cone is practically undefaced by 

erosion, and the outbreak is later than Lhe accumulation of the surrounding Pleistocene detritus which floors the valleys. Its age is therefore probably to be measured 

by hundreds of years only. This case is in some respects like that described by Professor Russell at Mono Lake, about 7 5 miles west-northwest of Silver Peak, where 

there are a number of volcanic cones (10 or 15) of very recent date, the lavas being in 

part hypersthene-andesite, in part rhyolitic.c These occurrences represent the most 

recent eruptions known within the arid Nevada-California province lying between 

the Sierra Nevada and the Colorado plateau region. 

The knowledge gained of the Tertiary lavas of the Silver Peak region is entirely 

the result of.the work of Mr. H. W. Turner, who has mapped the different rocks 

separately. In the accompanying map, based upon his work, they are all represented together, chiefly because the prime purpose of this report is to explain the ore 

a Am. Jour. Sci., vol. 3, Apr., 1897, p. 314. 

b Spurr, J. E., Trans. Am. Inst. Min. Eng., vol. 33, p. 332. 

c Eighth Ann. Rept. U.S. Geol. Survey, pp. 374, 375, 377,380. 
: .· ... -. . .. .. . .. . ........ . ::.·. !: .. ::: :: :~~: .. : . .. 

.. · ., .. •"' 

. . . . •'•• ••e• • •.• •,.• • .,.. •••••• •,.• . . ... . . ... . ...... . . . .. . .. . . 

.. . . . . . . . ..... ·.:··:·.·:·"~: :··: 

: .. ·::··.::~.:: .. : •• • •• * •• • • • •• . . .. . . ... . .. ... . ..... "' .. 

28 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

deposits, and the relations of these appear more clearly by uniting under one designation certain groups of formations. Mr. Turner has distinguished .and studied rhyolites, andesites, and basalts, with some dacites, and these lavas seem to have been 

repeatedly erupted at different periods. Rhyolites and rhyolitic tuffs cover large 

areas. This rock contains fresh orthoclase (sanadine), quartz, and biotite. The 

dacites occur chiefly in relatively thin layers in the rhyolitic tuffs. Andesites are 

abundant. Some of these are of alkaline types approximating the composition of 

latites. Others arc of the more ordinary andesitic composition. Basalt is also common, both hypersthene basalt and olivine basalt. 

The chemical composition of some of the Silver Peak lavas is seen from the following table of analyses: 

Analy8es of Silver Peale lavas. 

----L ~- 2._1_3. __ 4·-1 5. --~ 6. 

Rh~o- [ Rh~o- 'i _ I ' I lltf • 1 lltc, Dacite a A~de Basalt. Basalt spheru- gr.1no- · s1te.b I · 

-~c-~:(-F --:--::-:·:::---:--:-: ___ :: ___ -:·:::·-::-::-:::·::~-::- (~~I ~··~:·:,1 ~E -::~~~"II :~::~ FeO ............................................................ · .09 None. ........ 5.62 

MgO. ....... .................................... ............... .51 .17 3.55 7.06 

C<LO ........................................................ .. 1.37 1.37 c 1. 73 7.48 10.19 

NazO ....................................................... .. 3.40 I 2.80 3.90 3.28 2.37 

K,O ...................................................... .. 5.25 I 4.49 3.57 1.34 

u,o-.......... .. .21 .62 .66 

IIzO+ ...................................................... .. .97 3.65 2.37 

'I'i02 ... . .35 .19 1.19 

ZrOz ..... . .OG ········ ·······-·· ··-······ 

co ........................................................... . None. None. ·········· ----······ None. 

p,o., ........................................................ . .11 .07 ------··· ·········· .54 

S ........................................................... .. 

MnO ......................................................... . 

BaO ......................................................... . 

.03 

.10 .::::::::::::::::::1 None. 

.o:! .14 ' .......... ,.......... .17 

~-~~;-. ~~~~-;;~r~~~~~~:---~~; 

None. 

--------·-------~--------

a More properly, perhaps, a latite. 

b This bdongs rather with thEllatitcs, as Mr. Turner has determined. 

c Includes any SrO. 

These analyses were made by Mr. George Steiger. The materials were collected 

and described by Mr. H. '\V. Turner, except the last, which was collected by the 

writer. No. 1 comes from a point about 2~ miles southeast of Red Mountain. It 

has a spherulitic groundmass, containing crystals of orthoclase, quartz, biotite, a 

little amphibole, and a little plagioclase (apparently oligoclase). Titanite, magnetite, and zircon are also present. No. 2 is from a locality about 2 miles northeast of 

Emigrant Peak. It has a largely feldspathic granular groundmass, in which are 

crystals of quartz, orthoclase, and a little biotite. No. 3 has a glassy groundmass, 

containing crystals of orthoclase, albite, labradorite, biotite, some hornblende, 

augite, and quartz ( ?) . Magnetite and apatite are accessories. No. 4 is from the 

west slope of the Silver Peak Range, south of the Cave Spring road. It has a micro-
f 

U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 55 PL. Ill 

A. EDGE OF SILVER PEAK FLAT, 1} MILES SOUTHWEST OF PAYMASTER CAMP. 

Looking north. Shows streams of wash flowing down from the mountains of Cambrian rock and u niting to form a frontal 

wash apron. 

}i. D ETRITAL APRON FRINGING MOUNTAINS OF PROBABLY CAMBRIAN ROCK. 

Looking east on road from Silve r Peak to Tonopah , 3 miles north of Paymaster camp. Flat intermo ntane valley in 

foregrou nd. 
U. $, GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 55 PL. IV 

A. VIEW SOUTHWARD FROM NEAR THE LONE MOUNTAIN SYND ICATE PROSPECT. 

Shows mountains to south with their fringing wash apron. The foreground is a lower part of the general Lone Mountain 

wash apron. 

B. LAY ERING OF SUBAERIAL WASH. 

Section of western edge of Lone Mounta1n wash apron in nort heastern part of quadrangle. 
IGNEOUS ROCKS. 

granular groundmass, containing crystals of andesine, labradorite, biotite, and 

augite, with magnetite and apatite. ~o. 5 is from Pipers Peak. It is coarse 

grained and contains hypersthene and olivine, the former in larger amount. No. 6 

is from a butte 6 miles north of Silver Peak village, and represents an eroded flow 

lying on top of horizontally bedded ash and tuff. It is made up chiefly of feldspar 

(mainly anorthite, with some labradorite-bytownite) and olivine, with magnetite. 

Pyroxene may be present, but was no~ identified. 

QUATERNARY DE'I'RYI'US. 

PLEISTOCENE 

The Pleistocene deposits are not sharply divided either in point of time or in 

nature from those of the late Tertiary. A single series runs from one period to the 

other, representing the result of erosion under similar topographic and climatic conditions. But the amount of material laid down in standing water in lakes inclosed 

in rock basins was very considerable at various periods in the Tertiary, while the size 

of the areas occupied by such lakes seems to have been much diminished by Pleistocene time and to have grown still less by the present time. Quaternary lakes of any 

importance were not formed in the Silver Peak area. The detrital deposits, therefore, are almost entirely subaerial. The process of erosion is that which is typical of 

all this desert country. a The material worn from the bare mountain ridges travels 

down the slopes and accumulates at their bases in the form of a broad apron of 

inclined wash or drift (Pls. III and IV). Away from the immediate neighborhood 

of the mountain bases the detritus spreads out into a level sheet, chiefly, probably, 

through the agency of the fierce winds which frequently sweep through these valleys. 

In places the accumulation of the wash aprons and alluvial cones (gulch dumps) 

has been interrupted by recent crustal disturbances, involving tilting and probably 

faulting. Such is the case, as noted by Mr. H. W. Turner and subsequently by the 

writer, at a point at the west base of the northern part of the Silver Peak Range, 

east of the Pacific Borax Company's mill in Fish Lake Valley. As a result of the 

elevation of these gravels, they have become somewhat dissected and are fringed 

below with a new wash apron of recent detritus. Along most of the mountain 

front of the Silver Peak Range, ho\vever, no evidence of the interruption of the 

formation of these Pleistocene aprons by dynamic disturbance was noted. Along 

a considerable portion of the east front of the White :Mountain Hange, which lies 

next west of the Silver Peak Hange and is separated from it by Fish Lake Valley, 

earlier Pleistocene wash aprons have subsequently been dissected in the manner 

above mentioned; but the upper limit of the Pleistocene aprons seems to lie at 

about the same elevation on the two sides of the valley (about 5,500 feet, as mapped 

by Mr. Turner), and the apron on the Silver Peak side is a single unbroken one, 

representing, apparently, the same period of dissection as the two periods of the 

White Mountain apron. Therefore the writer is inclined to believe that the interruption of the formation of the \Vhite Mountain apron and the subsequent partial 

dissection of the portion already formed were not due to faulting and uplift, but 

a Spurr, J. E., Prof. Paper U.S. Geol. Survey No. 42, p. Ill. 

__ ____.-
30 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

rather to the advent in the White Mountains of the period of greater precipitation, 

which still continues. At a number of points on this east face of the White Mountain 

Range streams of running water leave the mountains and sink into the valley, 

affording water for a number of ranches. These streams are derived from the 

comparatively abundant precipitation, largely snow, which represents the overdrift 

from the Sierra Nevada precipitation, and which does not extend across to the 

Silver Peak Range. The effect of the erosion of this running water is clearly marked 

on the topography of the White Mountain side of Fish Lake Valley in contrast with 

the eastern Silver Peak side, in that the White Mountains are channeled by sharp 

canyons, at whose mouths the gulch dumps or alluvial fans possess far greater 

individuality and relief above the general wash apron than on the eastern side, 

where their relief is, in general, slight. 

PLAYAS. 

The sloping deposits of the detrital aprons which border the mountain fronts 

pass downward into lower and flatter Pleistocene deposits. In the lowest part of 

each mountain valley, hedged in between the different ranges, is a flat basin limited 

on all sides by the slightly higher detritus. Into this basin run and accumulate 

the waters after heavy rains or the melting of snows. At such times the basin 

becomes covered with standing water and is temporarily transformed into a shallow 

lake. Later the water which does not evaporate sinks beneath the surface. The 

material deposited from this standing water is a fine silt, which, when exposed 

by disappearance of the water, becomes a level mud. By further evaporation 

during periods of slight precipitation, the surface becomes very hard and smooth. 

Slowly, under the heat of the sun, the waters lying immediately below this hard 

crust are drawn upward and evaporate. In so doing they leave behind as a precipitate on the surface the mineral matters which they have taken into solution. These 

mineral matters often whiten the whole surface. They consist of salt, sulphate of 

soda, borax, etc. The areas covered by these deposits are popularly known as 

alkali flats, while by geologists they are called also pla:yas. One of these sinks 

exists in each of the valleys within the Silver Peak quadrangle~one in Clayton 

Valley (Pl. V), one in Big Smoky Valley, and one within the portion of Fish Lake 

Valley shown on the map. 

SA]I[D DF]I[ES. 

The leveling of the detritus derived from the erosion of the mountain ranges 

in the valleys has already been alluded to as probably chiefly due to the winds, which 

are frequent in this country. The surplus of finer material thus caught up by the 

wind accumulates in what appear to be natural wind eddies and forms heaps or sand 

dunes. In each of the valleys just mentioned there is such an area of sand dunes 

of comparatively limited and very definite extent. These sand dunes are not necessarily on the edges of the valleys, as might be expected, but are often in the very middle. 

During strong winds the sand in these dunes is taken up and driven horizontally 

with great force, and great quantities of this material are then put into motion. This 

vigorous shifting, however, seems to be very local, for the general outlines of the 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 55 PL. V 

HILL OF CAMBRIAN LIMESTON E ALMOST SUBMERG E D BY TERTIARY-QUATERNARY (QUATE RNARY AT SU RFAC E) VALL EY DET RITUS, 

Al catraz "Island" r.ear Silver Peak village in the midst of a "playa.'' View taken from Silver Peak. 
QUATERNARY DETRITUS. 31 

sand-dune areas do not change much, according to the testimony of inhabitants. 

The largest of these areas lies in Clayton Valley and is indicated on the map as surveyed by Mr. Turner (Pl. I). 

1\lOUN'rAIN S'rRUCTURE. 

The area in which the thick Triassic and .Jurassic strata were deposited in 

western Nevada and adjacent California was, according to King,a outlined at the 

close of the Carboniferous by the uplift of eastern Nevada. Although no Mesozoic 

sediments have been found in the Silver Peak quadrangle, they exist in quantity a 

short distance farther north, in the Pilot Range, b and undoubtedly once existed 

around Silver Peak. 

The plication of the strata of the Sierra Nevada into closely appressed and 

overthrown folds and its. upheaval as a mountain range took place at the close of 

the Jurassic, as has been proved by Whitney. The same profound disturbance is 

manifested in the smaller ranges lying east of the Sierra Nevada, though its effects 

grow less toward the' east. In the range next east of the Sierra Nevada there are 

overthrown folds like those of the Sierra Nevada, though the plication is not so 

intense.c Farther east, in the Silver Peak Range, the strata are complexly folded 

and faulted in a way which has not yet been deciphered. Still farther east the 

strata are bent only into open and easily recognized folds, though in some cases 

thrust faults have been observed, as in the Spring Mountain Range.d This indicates 

that the Nevada ranges shared in the same stresses as those which uplifted the 

Sierra Nevada, but chiefly in the western part, their effects increasing with proximity to the Sierra Nevada. This was also the view adopted by King.e 

In the Sierra Nevada the date of the enormous granitic intrusions coincides 

with that of the intense plication and uplift. In the smaller ranges lying east of it 

the writer has shown (see p. 25) that granitic intrusions of probably the same age 

occur, and most abundantly in the nearest ranges, as in the White Mountains. 

Thus the mountain-making forces at this period affected the western part of the 

Basin province, as well as the Sierra Nevada, but in a less degree. The latter range 

suffered a much greater and more general uplift, by which the western Nevada 

province was transformed into an elevated trough, shut off from the sea on the 

west by the new barrier (seep. 18.) 

This still relatively depressed belt contains no known sediments of proved Cretaceous age; so that this period was apparently one of erosion and free drainage. During 

the whole Tertiary, however, and down to the present, lake basins were repeatedly 

formed and again altered or destroyed by new crustai disturbances, accompanied 

by copious volcanic eruptions. Even at the present day the most depressed region 

of the dry Nevada province is along this belt, and the present lakes in it follow very 

roughly the old alignment. The depressed Death Valley, part of which is below 

sea level, is evidence of a continuation of the sinking of the crust, in places at least, 

down to the present day. Farther south this sunken belt is represented by the 

low-lying Mojave and Colorado deserts, and still farther by the Gulf of California. 

aU. S. Geol. Explor. 40th Par., vol. 1, p. 734. 

b Bull. U. S. Geol. Survey No. 208, p. 104. 

c See Spurr, J. E., Bull. Geol. Soc. America, vol. 12, p. 243. 

d Bull. U.S. Geo!. Survey No. 208, p. 177. 

e U. S. Geo!. Explor. 40th Par., vo!. 1, p. 747. 
32 ORE DEPOSITS OF SILVER PJ<;AK QUADRANGLE, NEVADA. 

It is not probable that such crustal disturbances could be accomplished without 

folding and faulting, resulting in local elevations and depressions within the affected 

belt; so it is natural to expect to find in this belt both mountains and valleys whose 

configuration is due primarily to deformation rather than to erosion. a And there are 

indications that this is actually the case, though sufficient study has been made to 

demonstrate it in but few places. The Funeral Range and the adjoining Death Valley, 

as already noted, seem to present one instance, though no detailed examination has 

been made.b 

The Tertiary deformation has been contemporaneous with great volcanic 

activity. Therefore the two chief periods of deformation (including faulting and 

folding) and mountain making which we can distinguish for the province in which 

the Silver Peak r~J,nge lies were periods of great igneous migrations. The writer has 

elsewhere presented some evidence for believing that the Tertiary deformation 

was, in part at least, the direct consequence of the 11va migrations, instead of both 

being due to a common unknown cause. c 

The rock structure of the Silver Peak range is known to be complicated-to 

such an extent, indeed, that it has not been worked out. The presence of complicated folds and faults is certain. The north face of the range (at the extreme northern part of the map) presents a bold fault scarp overlooking lower-lying Tertiary beds 

farther north. This was pointed out by :Mr. H. vV. Turner, and the '.'Hiter has corroborated the fact that a fault lies along this scarp, though it is not yet determined 

whether the scarp is directly due to the faulting or is due directly to the erosion of 

rocks of unequal resistance brought together by the fault movement. The observations of the writer indicate that this may very likely be a reversed erosion fault 

scarp, the relatively down thrown side forming the scarp, but more work is necessary 

before any final statement is possible. The straight northeast face of the range, 

running northwestward from Silver Peak village, suggests faulting, and the writer 

has observed what may be a fault parallel with this face and near the base of the 

range. It does not, however, lie at the junction of the bed rock with the valley 

accumulations, but runs along a depression in the bed rock near the base of the 

mountain. The probable fault which lies in this depression separates brown Cambrian dolomites on the northeast from the lower-lying slate and limestone formation 

which has been thoroughly injected by granitic and alaskitic material. Here again 

there is no evidence as to whether the scarp behind the fault is directly due to uplift 

or to erosion. Other fault lines probably exist, such as that observed by Mr. Turner 

on the west side of the range, at a point east of the Pacific Borax Company's mill in 

Fish Lake Valley. This is a north-and-south fault, which separates the Paleozoic 

limestones on the east from the Tertiaries on the west, and is also accompanied by a 

scarp. At other points the outline of the mountains in respect to the valleys often 

suggests faulting, but the evidence as to the real origin of the configuration has not 

been satisfactorily determined. So in general we can only say that there is evidence· 

of local crustal movements in the Tertiary and even of some in Pleistocene time. 

a Spurr, J. E., Origin and structure of the Basin Ranges: Bull. Geol. Soc. America, vol. 12, pp. 239,241,247. 

b Spurr, J. E., Bull. U.S. Geol. Survey No. 208, p. 194. 

c Geology of the Tonopah mining district, Nevada: Prof. Paper U.S. Geol. Survey No. 42, p. 81. 
MOUNTAIN STRUCTURE. 33 

The Tertiary beds are in places arched up over the lower part of the Silver Peak range, 

but are not near the highest elevations. Flexing and faulting, accomplishing an 

uplift of the range in Tertiary time, is thus attested, though the fact that the upper 

portions of the range show no Tertiaries suggests that the mountains existed before 

the Tertiary period. In short, our knowledge of the structure and origin of these 

mountains and valleys is small. We are certain that great erosion and considerable 

deformation were contemporaneous, in the Tertiary and even in the Pleistocene, but 

the resulting balance between these forces in producing surface configuration is in 

almost every case uncertain, on account of the lack of thorough investigation. The 

writer, however, regards it as probable that part at least of the surface configuration 

may be due to direct deformation. 

13002-No. 55-06--3 
• 

OH A_PTER II. 

DESCRIPTION OF ~IETALLIF:B_JROUS DEPOSITS. 

HI8TOHY OF MINING. 

The Silver Peak or :Mineral Ridge district is the oldest and probably the most 

important of the several mining districts of the quadrangle. It contains abandoned 

silver mines and also gold mines which have been considerably worked, but are still 

regarded as of potential value. The silver deposits were discovered in 1864 by the 

Robison Brothers, but were shortly left idle. In 1867 they were opened up again 

and worked until 1869. It is currently reported that the profits were small. They 

have not been worked since. The principal mines of the region are the Drinkwater 

or Blair group, which are gold ores. A 30-stamp mill for working the ores of these 

mines was finished at Silver Peak in 1867 and was worked for two years (Pl. II, B). 

The mine was then idle until the early eighties, when it was leased for two or three 

years. Another long period of idleness followed, and in 1893 another lease was given 

for one year. Immediately after this the mine became involved in litigation, which 

has been settled only recently. Mining and milling in a small and intermittent way 

has meanwhile been conducted on a number of properties, generally of minor importance, outside of the Blair mines. 

It will be seen that the development of this older Silver Peak district (the 

Mineral Ridge district) was independent of the development of Tonopah, which was 

discovered in 1900; but the other mineral districts of the quadrangle mostly followed 

the Tonopah discovery, and the attention which is or has been drawn to them was 

due to the revival of prospecting and investment thus brought about in this country. 

Around Lone Mountain some old prospects were examined and worked a little 

many years ago and then abandoned. With the revival of prospecting above 

referred to, these were relocated and some new ones were found. ~fany of these 

locations have not proved of value. On the other hand, a number of mines which 

were thus started have produced considerable ore. Not all the mines of the 

Lone Mountain district are covered in this report, but only such mines and prospects 

as are included within the quadrangle or are immediately adjacent. 

The prospects on the west side of Silver Peak range, 1 mile east of Dyer's 

ranch, in Fish Lake Valley, were located in 1885-1887, and this district was the scene 

of a short-lived excitement, but was afterwards abandoned. Following the Tonopah 

discovery, it was relocated, but no new work was done, and at the time of the writer's 

visit it was again deserted. The Windypah, or Fesler, district, in the so'uthwestern 

part of the quadrangle, east of Piper's ranch and· in the Silver Peak Range, was discovered in .. the winter of 1903 by J. G. Fesler. An abandoned mine or prospect, the 

34 
U.S. GEOLOGICAL SURVEY 

Gf-3 

rJf.~ ~,ArJ co~ 1zS. 

~·c.l·. 

' \ 

' ' \ 

' \ 

' ' ' 

PROFESSIONAL PAPER NO. 55 PL. VI 

8 f;. 

Summit 

Scale of feet 

0 300 600 900 1200 1500 

CLAIM MAP OF BLAIR MINES AND TIETJEN MINES. 

Scale, 100 feet=l inch. 
HISTORY OE' MINING. 35 

Good Hope, has existed for many years at a point a number of miles north'last of 

the district. Considerable prospecting had been done in the Windypah district at 

the time of the writer's visit, but no actual mining. 

In the extreme southern part of the quadrangle, on the north slopes of the Palmetto Mountains, are certain prospects belonging to the Palmetto district. Farther 

south and outside of the quadrangle more important deposits belonging to the same 

general district exist, but are not treated in this report. The principal prospect 

within the quadrangle is the MacNamara, located in 1880. Another example of 

prospects in this vicinity is the Paymaster, which must be distinguished from the 

Paymaster of the Lone Mountain district. This was located ten or twelve years 

ago, but was abandoned and relocated in 1902. None of these prospects have produced any considerable amount of ore. 

At the base of the northern end of the Silver Peak range coal beds exist. The 

coal is said to have been discovered by William Grozenger, of Candelaria, in 1893, 

and the outcrops of the coal seams were afterwards continuously located. These 

prospects have been bonded several times, once by the Tonopah Mining Company, 

and some development work has been done on the seams, but up to the present time 

there has been no mining. 

PHODUCTIO~. 

Statistics concerning the production of the mines of Mineral Ridge were given to 

the writer by Messrs. F. A. Vollmar, John Chiatovich, and Otis Valcalde, of Silver 

Peale Although these statistics depend largely upon personal recollection, it is 

believed that they are fairly accurate. According to this, the Blair group of mines, 

including the Drinkwater, Crowning Glory, and Western Soldier (Pl. VI), have produced a total of $1,080,000. Close to these groups and on the same zone of ore 

lenses are the Homestake, with a credited production of $60,000; the Mary with 

$46,000, and the April with $10,000, making a total of $1,196,000 for this zone of 

lenses. 

Outlying mines of similar character to those of the Drinkwater zone, scattered 

over Mineral Ridge, are reported to have produced the amounts stated below; 

Production of mines on Mmaal NidrJe. 

May............................................................. . .................................. $4,000 

Columbus .... _-- ....... _ ... ---- .. -- __ -- ........ _ ....... -- __ ..... ___ ..... ___ ..... ____ .. _. _ ... . 3,000 

Vega .. - ......... ----.---- .. ----.- ..... --.-.-- .. --.-.-- ..... -----.------ .... -- .. -.- ...... -- ... ---- ... _ .... __ .... __ ... 3,000 

Crescent .... --------.-- ..... ------ .... -----.- ... ------ .... ---.--- ... -- __ -- .. --_ ... __ --- .. ______ .. __ ... . 2,500 

Solbcry .. ------------ ....... ---- ....... --.- ..... ----.-- .. _. ___ ...... __ .. .. . .. . ...... _ .... _ .... _ ...... ____ . 2,000 

Golden Eagle .... __ . _ . _ ...... _ . ___ ..... __ . ___ ....... _ .... _ . _ .. ___ ... _ . _. _. . _ . _. _ ....... ___ .. _ .. _ ... _ . _. . ..... _ ..... _ _ 000 

Esmeralda .... _ .......... __ .................. __ .... -- __ ............. __ ._. __ ..... _ ........ _._ .......... __ .............. 400 

Red Monster . _- .............. ____ ....... -- ................ ____ .... __ .... _______ ....... ______ . _ .... ____ .. __ ... __ .. ... . 300 

Total. ................ ------ .... ------ .............. ___ ..... _._ ....... _. __ ........ _. ______ ... __ . __ .. ____ . ____ . __ . 16,100 

The Great Gulch mine, which is of somewhat different character from those just 

mentioned, has produced about $6,000. The foregoing values are almost entirely 

in gold. 

The silver mines of the ridge, chiefly the Pocatello and the Vanderbilt, have 

produced, as estimated, about $200,000, making the total production of Mineral 

Ridge $1,418,000. 
36 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

That part of the Lone Mountain district which lies within the map has produced 

only trifling amounts, all the deposits being mere prospects. Beyond the limits of 

the map, however, some of the mines of the Lone Mountain group have produced 

considerable ore, the amount of which has not been estimated. The Alpine mine, 

beyond the northern edge of the quadrangle, paid a dividend of $70,000 in the first 

year of its workings (1903). Considerable shipments of ore have also been made 

from other properties in this district. 

The other districts mentioned are all in the prospecting stage and have produced 

only trifling quantities of ore. 

DESCRIPTIVE GEOLOGY 01'~ MINES AND PROSPECTS. 

GOLD MINES AND PROSPECTS OF MINERAL RIDGE. 

DRINKWATER TYPE. 

DRINKWATER AND CROWNING GLORY MINES. 

EXTENT OF WORKINGS. 

The Drinkwater and Crowning Glory mines form a group comprising the most 

important mines of the quadrangle. They have been operated at intervals for about 

forty years and have produced a gross total in the neighborhood of $1,000,000. 

The developments consist of numerous open cuts (Pl. VII, A) and underground 

workings reached by two tunnels. The upper or Drinkwater tunnel (Pl. VII, B) 

runs in on the vein zone, and the workings from it are those from which the greatest 

production has been derived. The lower or Hickey tunnel is an adit level running 

into the ore zone and has been used for development rather than for production. 

ORE IN SIGHT. 

Besides the ore produced, named above, great quantities of auriferous quartz are 

exposed on the surface and in the underground workings. On this account examinations by engineers have been made a number of times. One of these examinations 

was made by Mr. George M. Maynard, of New York, through whose kindness the 

results obtained have been placed at the writer's disposal. The ore, it may be,stated 

in advance of the more detailed description, occurs in lenses of quartz, which occupy 

a definite zone. At the main workings a large lens outcropping in the lower part of 

the zone has been called the Crowning Glory vein, while smaller lenses in the upper 

part of the zone have been called the Drinkwater vein. Between the two in the 

middle part of the zone are other lenses, which by some have been named the 

Magazine vein. The exhaustive sampling conducted by Mr. Maynard gave the 

measurable reserves of the underlying Crowning Glory zone at 107,370 tons w1th an 

average assay of about $5 a ton, and a total value of $537,550. The quartz thus 

sampled averaged 8.2 feet thick. The dumps from the Crowning Glory workings 

were found to contain 12,757 tons, having an average value of about $8.80 a ton and 

a total value of $112,340. Twenty-four boundary assays from outcrops and worki:p.gs of the Crowning Glory zone, outside of the ore actually measurable, were made 

and gave an ave.rage value of $10.59, the average thickness of quartz sampled being 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 55 Pl. VII 

A. CROWNING GLORY LENS ZONE, DRINKWAT ER MINE. 

Open-cu t work ings and mouths of tunnels. 

B. ENTRANCE TO UPPER WORKINGS, DRINKWATER MINE. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 55 PL. VIII 

LEGEND 

Quartz 

~ lenses 

' 

Alaskite 

. 

20° 

j_ 

Dip 

~ 

~ 

Schist 

~ Diorite 

Scale of f ee t 

0 50 100 200 

HORIZONTAL PLAN SHOWING GEOLOGY EXPOS E D I N HICKEY T U NNEL WORKINGS ( LOWER T UNNEL OF D RINK WATER MINE). 

Shows shape and geological relations of aunferous quartz bodies. 

300 
u. S. GEOLOGICAL SURVEY 

sw 

0 25 

PROFESSIONAL PAPER NO. 55 PL. IX 

LEGEND 

Quartz 

~ lenses 

~ Alas kite 

5chist 

Scale offeet 

50 

(Entrance to main tunnel, 

+ Drinkwater vein 

c"'''-'c"~~~""-

75 100 

VERTICAL CROSS SECTION OF CR OWNING GLORY-DRINKWATER O RE ZONEc 

S~etched from surface open cut and underground workings along line A-A', mine map, Pl. VI ~ Scale, 30 feet = 1 inch. 

NE 
U. s. GEOLOGICAL SUfiVEY 

LEGEND 

Quartz 

~I lenses 

. 

' 

s~~;~~,, 

1 Diorite 

? 

.... 

~ 

0 

E 

'-' 

4> 

c 

c 

,3 

VERTICAL CROSS SECTION OF 

PROFESSIONAL PAPER NO. 55 PL. X 

o E:=c=~5Eo~==I~O~~~c=a=le~of~~f<~e:eJt~=======-~ 200 300 

DRINKWATER MINE ~~:::~~:::-:~------------- Taken alo I WORKINGS SH on plan, Pl. VI. LENSES, ng lne A-B OWING QUARTZ 
GOLD MINES AND PROSPECTS OF MINERAL RIDGE. 37 

5.6 feet. In the intermediate or Magazine zone of lenses 12,000 tons of ore were 

measured, having an average value of about $4.37, giving a total value of $52,440. 

In the Drinkwater or upper zone the measurable reserves were computed to be 4,588 

tons with an average assay value of $9.18, making a total valuation of $42,118. At 

the bottom of the Brunton shaft (Pl. X) the quartz lenses (which had just been cut at 

the time of the examination and had not yet undergone the development shown in 

Pl. VIII) yielded from the results of eleven general assays an average value of $9.51 

for an average thickness of 7 feet. Outlying quartz lenses on this property (the 

Blair property, belonging to Mr. D. C. Blair, of New York) were also sampled by 

Mr. Maynard and showed values everywhere very similar to the above. Outcropping 

lenses are found here and there nearly to the top of the ridge which lies south of the 

mine. 

Since Mr. Maynard's examination a number of years ago a considerable amount 

of new development work has been done which increases marked.ly both the measurable and the probable ore reserves. This has 'been done chiefly from the Hickey 

tunnel, and the results of these measurements are not available. 

NATCRE OF ORE. 

The ore is a typical white crystalline quartz, which under the microscope is seen 

to be crowded with liquid inclusions. It sometimes contains original muscovite and 

rnore rarely small chlorite (var. ripidolite ?) crystals. In this quartz the values are 

chiefly gold. Silver, which is nearly always present, has an average value of about 

1 per cent as compared with the gold. The gold is usually finely disseminated and in 

a free state, although it is also contained in scattered pyrite and rare galena, which 

occur sparsely through the quartz and are contemporaneous with it. Measurements 

have shown that these sulphides constitute about 1 per cent of the volume of the 

quartz. Mr. Maynard took an average sample from all his other samples procured 

for assay purposes, and from this separated 98 pounds of ore. From this the sulphides were concentrated and upon assay showed a value of $68.63 to the ton. The 

gold seems to be contained in the sulphides in a free state, since it was removed by 

amalgamation. Since the ore from which these sulphides were concentrated was an 

average of all samples taken we may roughly place its value at about $5 a ton. 

From a ton of such ore 1 per cent of sulphides, having the assay value above given, 

represents a value of only 68 cents. The remaining $4.32 or thereabouts is probably 

present as free gold. 

The value of the quartz, however, is not regular. It is spotted, occurring in 

richer and poorer portions of irregular extent. Therefore certain lenses and certain 

groups of lenses may have a relatively high grade of ore, while others may be low 

grade or nearly barren. Thus, the ore now left in the mine, as is shown by Mr. Maynard's assays, has a value of $4 to $9 per ton on the average, but the ore which has 

been extracted and milled is said to have averaged $20 a ton. It must have been near 

this to give a profit under the high expense of hauling and milling. The large 

Chiatovich stope in the Drinkwater workings (Pl. XII) contained the richest ore and 

is said to have yielded values of $40 to the ton on milling. Chiefly from this stope 

Mr. Chiatovich took out a gross total of $196,000. Mr. Samuel Wasson, of Silver 

Peak, who was one of the leasers at a different period, reports having taken out a 
38 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

total of 3,000 tons, yielding a value of $16 to the ton on amalgamation, while the 

tailings contained about $7, most of which would be recoverable by cyaniding. 

Besides the white vitreous quartz of the ordinary type there is a dense bluish 

variety, locally known as bull quartz, which, however, grades into the ordinary 

variety. As a rule this is held to contain less gold than the ordinary quartz, although 

values are practically always present, and some of this quartz contains more than 

some of the ordinary variety. A general sample taken by the writer and Mr. R. M. 

Geppert from the bluish bull quartz near the mouth of the Hickey tunnel (locality 

A, in Pl. X) was found by F. A. Vollmar, of Silver Peak, to contain gold, 0.00; by R. 

H. Officer, of Salt Lake City, to contain gold, 0.007; silver, 0.03 oz. Farther south in 

the same tunnel (locality C, Pl. X) similar quartz yielded F. A. Vollmar gold, 0.0025 

R. H. Officer, gold, trace; silver, 0.015. This bluish quartz occurs in lenses similar to 

the lenses of the ordinary variety. . 

NATURE OF ORE BODIER. 

The ore occurs in lenses of various dimensions, as seen in both horizontal and 

vertical plan. (See Pis. VIII, IX, and X.) Along the ore zone these lenses 

typically overlap. They disappear by wedging out; frequently, also, by forking or 

splitting into several forks, in which case the country rock comes in in layers between 

the quartz bands. Therefore, a series of quartz stringers in the country rock may 

unite laterally o~ vertically and widen to 3 or 4 feet of solid quartz. The result is 

great complexity, as may be seen in the maps of the stopes in the Drinkwater upper 

tunnel workings. These maps (Pl. XI, A, B, 0) represent three sections parallel to 

the vein zone and separated only a few feet from one another; yet the stopes upon 

one section can not be identified from the maps with those upon an adjoining one. 

The quartz lenses seem to accompany intrusions of alaskite wherever the latter 

occurs on Mineral Ridge. Though they always contain gold, as determined by Mr. 

Maynard's assays, only in some of them is the amount sufficient to have warranted 

their handling. These more highly auriferous lenses are bunched in certain zones, 

in certain groups of each zone, and especially in certain lenses of each group. Such 

a bunch of lenses is represented by the main stopes in the Drinkwater tunnel workings, shown in vertical cross section in Pl. XII. A smaller bunch of lenses on the 

same zone is found near the mouth of the same tunnel. In general it seems that 

very large lenses are apt to be of lower grade than small ones. 

These lenticular quartz bodies have probably their original form and have not 

been produced by crushing and shearing, as was at one time supposed by the 

writer. This is shown by the fact that their wedging out is not attended by unusual 

movements or shearing in the rock, and the fact that this wedging out is characteristically accomplished by a fraying near the edges and splitting into different sheets, 

between which lie gradually thickening wedges of country rock. Also the phenomena of splitting and reuniting as shown in the different sections (Pl. XII) is not compatible with the idea that the form is due to movement. The richest stope in the 

mine, the Chiatovich stope, is formed by the uniting of several smaller quartz bodies, 

as seen both in horizontal and vertical section. 
GOLD MINES AND PROSPECTS 01!' MINERAL RIDGE. 39 

EXTENT OF LENSES. 

The Drinkwater Crowning Glory group of quartz lenses lies in a zone 100 feet 

or more wide, which outcrops for a mile or more along the mountain side and dies 

z 

?~:;;-.,'/ //" 

;,je! ly )' I ~'.J), '/,, /; 

(_J,/. / 

{;:/;j// ~ v j: t:l~{; ~~ .. t" ;({/~;' 

~~ ~'\- /}J:~ / (;-~~ ~~ 'JJ '@' 7 I 

~-?'Y. tlJ:t /'-../ 

.o_, rv / i / ~~"v l>.n . /~,(, /(., I ,,,. 

' . / ;-'') 

•.. >\.<i/ ~".Y.s-@: ~"r ... ~~. ' / 

'/~· ':' / ( '/:· 

/'.'¥~ 

•<ll /. -/J'~< 0 

out in both directions. From this it seems prob-

:> able that the zone will die out also at a certain 

~ depth, though exactly where is uncertain. As-

; suming that the original vertical extent of the 

> R ore zone was about the same as that shown by a 

'" horizontal section, we must conclude that the 

;:;:; 

c: zone would probably extend downward on the 

dip for less than a mile-perhaps very much 

less-for it is evident that the upper part of the 

zone-how much we can not tell-has been removed by erosion. 

In general the lenses and the lens zones dip 

northward with the formation, which is a series 

of thin-bedded limestones and limy slates that 

have been intruded and somewhat altered. 

NATURE OF WALL ROCKS. 

Altered limestone and limy shale.-In the 

£ stopes of the Drinkwater tunnel the wall rock is 

~ usually schist mixed with quartz and granitic matl terial. Sometimes it is alaskite and rarely unal-

" " tered limestone. In the lower or Hickey tunnel ~ alaskite is the commonest wall rock, although 

-~ limestone and schist are frequent. The schist 

~ has been found by the writer to be derived by 

~ metamorphism from a series of thin-bedded cal-

·2 careous sediments, which may be classified as blue 

'; limestone and limy shale. Sometimes these rocks, 

~ especially the limestone, occur even in the wall 

rock of the quartz bodies in a practically unaltered 

condition. Often, again, the limestone is filled 

with siliceous material in the form of seams, lenses, 

and nodules, and is thoroughly altered, chiefly by 

silicification. (Pl. XIII, A.) Sometimes, near 

quartz or alaskite bodies, it is altered to mica 

.<1 schist, which wraps around the lenses of quartz 

~ or alaskite. Occasionally the microscope shows, 

I mixed with the finely crystalline calcite of the ,..; 

<.'i limestone, green hornblende, epidote, quartz, and ~ feldspar as products of metamorphism. 

On the road in the canyon leading up to the 

Drinkwater mine a number of massive marble beds as much as 60 feet thick are intercalated with these dark-blue thin-bedded schistose slates. (Fig. 1.) 
40 ORE DEPOSITS Oil' SILVER PEAK QUADRANGLE, NEVADA. 

Ala.skite.-Alaskite occurs in the mine workings, as shown in the figure, in about 

the same forms as the quartz lenses. The same facts are displayed by the outcrops. 

(Fig. 2.) The shape of these lenses is original, like that of the quartz lenses, and the 

same proofs are at hand. Thin intercalated sheets of alaskite often unite to form 

large lenses. In making a certain surface cross section (fig. 3) it was found that 

alaskite lenses which did not cross the section line were 2 feet in thickness at a distance of 10 feet from the line and became 20 or 30 feet thick at a distance of 100 feet. 

As seen on the surface the alaskite lenses are somewhat larger than those of quartz. 

These masses of alaskite and quartz have been intruded into the bedded limestone 

and are generally intercalated in the strata in large and small sheets, though they are 

in places cross cutting. The intruded sheets vary in thickness from many feet to the 

tenuity of a sheet of paper and are in places interlaminated with thin plates of schist, 

like the leaves of a book. 

The alaskite has most frequently a typical granular structure like that of granite. In places it is fine grained or aplitic. Elsewhere it is coarse and passes into 

pegmatite, or it is fine grained or medium grained and is banded, possessing what 

may be designated as an original gneissic structure. 

FIG, 2.-Vertical sketch section showing lenses of siliceous alaskite (passing into quartz) in schist (altered shalv limestone). 

from surface at Blair mines. · ' 

Mineralogically the rock consists of quartz and feldspar, including orthoclase, 

microclihe, and a striated feldspar, which is sometimes an orthoclase, sometimes 

albite (or oligoclase-albite). Muscovite is an accessory, usually of small amount 

and in small flakes, although occasionally it becomes important. An occasional 

phase contains biotite and becomes therefor a siliceous biotite granite, but this phase 

passes by transition into alaskite and is unimportant in amount. 

Microscopic study of the alaskite from these mines brings out the fact that the 

crystallization was rather slow and interrupted and is represented by more or less 

distinct generations. For example, a specimen from the Hickey tunnel shows a first 

generation consisting of coarse quartz, microcline, orthoclase, and an undetermined 

striated feldspar. The striated feldspar contains some fine muscovite along the 

cleavage lines. Similar muscovite is present in some of the orthoclase and quartz 

grains, while others are clear, as if these minerals consolidated at different periods. 

The microcline is always clear. The second generation of crystals occurs between 

these large grains and consists of a fine granular aggregate of the same minerals, 

including quartz, orthoclase, microcline, and oligoclase-albite, all fresh, with 
U.S.GEOLOGlCAL SUR VEY 

LEGEND 

~ Workings in upper part of zone 

~ Workings in middle part of zone 

~ Workings in lower part of zone 

LOWEST WORKINGS 

Wi 10 

MAP OF CHIEF STOPE WORKINGS, DRINKWATER MINE. 

PROFESSIONAL PAPER NO. 55 PL.XI 

Scale 

20 30 40 so feet 
U. S. GEOLOGICAL SURVEY 

o 25 Scale of feet 

E3c=~c=~~======~5~0~~~~~7~5~======~ 100 

VERTICAL CROSS SECT ION OF CHIEF STOPE WORKINGS, 

PROF£SSIONAL PAPER NO. 5$ 

LEGEND 

Quartz 

~ 

~ 

lenses 

~ 

~ 

Alaskite 

-

- Schrst 

DRINKWATER MINE. 

PL. XII 
• 

GOLD MINES AND PROSPECTS OF MINERAL RIDGE. 41 

numerous grains of calcite, which may also be contemporaneous. Fresh oligoclase-albite in one case was noted to 

contain an irregular geode-like inclusion of calcite. A very little chlorite is 

present in this second generation. A 

similar succession is seen in another 

specimen from the Hickey tunnel, but 

it is interesting that in this second case 

the amount of material of the second "J generation is very trifling, the rock !5 

being almost wholly made up of the 

first generation. Where this second 

generation does occur, however, the 

fresh quartz and feldspar include calcite rhombs and crystals of zircon. 

Another specimen from the mine shows 

a still more interesting succession of 

generations. The first generation con- ::;. 

sists of feldspar, chiefly idiomorphic. E 

The interstices between the feldspar ~­

crystals are filled with allotriomorphic ~ 

quartz, which sometimes cuts across ~ 

the feldspar, following cracks. ~ 

As a rule the quartz in these rocks s 

is both contemporaneous and slightly ~ p; 

later than the. feldspar, the two rela- g 

tions being shown almost always in a _! 

single slide. The orthoclase sometimes 

incloses quartz grains, and quartz may ~ 

be found included in microcline as c 

well as microcline in quartz, such cases 

showing contemporaneous crystallization. The quartz is in places segregated into irregular bunches, or into 

chains or strings more or less vein-like 

in appearance, though in the same ! 

sections the quartz and feldspar are : 

intergrown and are practically contemporaneous. 

The alaskite sometimes contains 

original pyrite and frequently small 

zircons. Both the quartz and the feld- · 

spar are characteristically fflled with 

tiny liquid inclusions. 

An interesting study is afforded by 

the muscovite in the rock. This grades 

0 

~ 

8 

~ OK' Cl> 

i> 

"' 0 

0 

8 

8 

;:-

~ 0 

0: 

0 

., 

s· 

"" 

~ .. ::D 

., 

,. 

c: 

::l 

::l 

!!. 

r 

8 

1'1 

z 

0 

m size from the larger flakes, alway~ 
\ PLATE XIII. 

PEGMATITE QUARTZ FORMING VEINLETS IN EARLIER CRYSTALLIZED FELDSPAR . 

.A, Reproduction of photograph, actual size, of polished specimen (No. 17) of alaskite pegmatite from a feldspathic portion of the Homestake veins. The light portions (f) arc feldspar (minocline); the dark 

portions (q) are quartz. The quartz, while an essential rock constituent and an Pssential portion of 

the rock fabric,is of later crystallization than the microcline, in which it lies in part veinwise,in part 

in isolated grains. 

GNEISS DUE TO INJECTION OF LIMESTONE SHALE BY ALASKITIC MATERIAL. 

B, Heproduction of photograph, actual size, of polished specimen (No. 16) from the wall of the Crowning Glory 

vein. Shows gneiss produced ry interposition of numerous thin sheets of alaskitic material (quartz and 

feldspar in varying proportions) between the laminm of limestone shale, with attendant metamorphism 

of the latter. 

42 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 55 PL. XIII 

B 

A. PEGMATITE QUARTZ FORMING VEINLETS IN EARLIER CRYSTALLIZED FELDSPAR. 

H. GNEISS DUE TO INJECTION OF LIMESTONE SHALE BY ALASKITIC MATERIAL. 
GOLD MINES AND PROSPECTS OE' MINERAL RIDGE. 43 

recognized by the name of muscovite, to successively smaller proportions till it sinks 

gradually to the fine fibers which are ordinarily called sericite. Microscopic study, 

however, in many, probably most, cases shows a community of origin for the materials of different sizes, so that the writer will refer to all as muscovite. a 

The coarser muscovite in some places occurs in grains of sizes equal to those of 

the grains of other minerals and is intergrown with tlfem. As a rule, however, it is 

smaller than the quartz and f~ldspar, and occurs in characteristic flakes included 

in them, but especially in the feldspar. When it becomes very small, the feldspar which incloses it comes to have all the appearance of a sericitized feldspar in 

which the muscovite has arisen by a process of alteration. Indeed, in many cases 

the fine muscovite is so arranged, being parallel with the cleavages and even occuring along fractures in the feldspar, that the conclusion that it is an alteration product 

is inevitable, although the transition is perfect between this and increasingly coarser 

types and all seem to have a common origin. It is characteristic that in such a rock 

certain feldspars may thus contain fine muscovite, while adjoining ones are perfectly 

clear. The microcline of the rocks is almost always clear. This mineral, as is well 

known, is one of the last to crystallize from a granitic magma; indeed, it is known to be 

frequently later than quartz.b In several cases it has been noted that striated feldspar in a given thin section was considerably altered to fine muscovite, while the 

orthoclase was less altered and the microcline not at all. In such cases the secondary muscovite is not always fine, but becomes coarser and approaches the ordinary 

granitic variety, while retaining its relation to cracks and cleavages in the feldspar. 

In this connection the description already given of a phase of alaskite consisting of 

two generations may be recalled where the older generation of feldspars, which consisted of striated feldspar, orthoclase, and microcline, had been considerably attacked 

and altered to fine muscovite fibers-the striated feldspar most, the orthoclase less, 

and the microcline not at all; while the later generation, consisting of all these feldspar species, namely, microcline, orthoclase, and oligoclase-albite, were quite free 

from alteration, though they were associated with some contemporary muscovite. 

In another specimen from the Hickey tunnel the orthoclase was found to be considerably altered to fine muscovite, while the striated feldspar and microcline were fresh. 

The conclusion from these facts is that the muscovite in the rock (which is 

usually of a fine variety) has been formed chiefly by alteration of the feldspar at 

stages of partial crystallization. Thus the early feldspars are altered, the later ones 

not. The crystallization of muscovite in general seems to be dependent upon the 

action of fluorine, and it may be that this factor determines whether in a given magma 

or solution an orthoclase molecule is formed or a muscovite molecule with a little 

quartz. Similarly, it is probable that the already formed orthoclase molecule may 

be easily decomposed to muscovite and quartz by the action of fluorine, with the 

help, perhaps, of other agents. Therefore feldspars in the vicinity of mineral veins 

are frequently muscovitized or sericitized. In the case now under consideration the 

alteration of those feldspars which formed first from the crystallizing magma has 

probably been accomplished by excess of fluorine in the residual granitic fluid. The 

alteration is therefore endomorphic.c 

a See Spurr, J. E., Geology of the Tonopah mining district, Nevada; Prof. Paper U.S. Geol. Survey "No. 42, p. 232. 

b Harker, Alfred, Petrology for Students, p. 28. 

c Spurr, J. E., Quartz-muscovite rock from Belmont, Nevada: Am. Jour. Sci., vol. 10, Nov., 1900. 
44 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

Besides the muscovite or sericite which has this origin it appears that some fine 

muscovite (sericite) may also be due to alteration subsequent to the crushing which 

the rock has frequently undergone (though none of the occurrences previously 

described were in crushed rocks). In certain places fine muscovite is seen to haev 

formed along a shear crack. In some cases, therefore, the portion of this minhal 

produced by endomorphic action may not be readily distinguishable from that due 

to metamorphism. Since the outcropping alaskite typically shows feldspars which 

are largely fresh, it is probable that weathering is unimportant as an additional factor 

in this change. 

Diorite.-The limestone, limestone schist, alaskite, and quartz, which constitute 

the main mass of the rocks in the vicinity of the Drinkwater mines, are cut through 

by a considerable number of rather thin diorite dikes. These dikes frequently cut 

across_the veins, without suffering any great deflection. Sometimes, however, they 

0 s feet 

FIG. 4.-Vertical section in drift, Hickey tunnel, showing intrusive diorite splitting earlier quartz lens. A, Coarse alaskite 

(country rock of quartz); Q, qnartz; D, diorite. 

have followed the veins, these being in such cases along the zones of least resistance. 

The diorite is frequently intruded between the vein and its wall and so itself comes 

to form a vein wall. This, for example, is repeatedly found in the Hickey tunnel 

(Pl. VIII). Occasionally the vein is split by the diorite, which lies in the middle as 

a parallel intrusive sheet (fig. 4). 

For field use the term greenstone is more descriptive of this rock than the term 

diorite, for the rock is generally entirely decomposed and is now an aggregate of secondary products, chiefly chlorite, calcite, pyrite, quartz, sericite, z(:1olites, etc. Originally the rock was composed chiefly of hornblende and feldspar, now recognized by 

pseudomorphs consisting of decomposition products. Ilmenite is abundant. 

RELATION OF QUARTZ I AND AI.ASKITE. · 

The typical quartz and typical alaskite form two ends of a rock series between 

which there is every gradation. All these intermediate stages are abundantly represented in and ~round the Drinkwater mines. The alaskite and the quartz have the 
GOLD MINES AND PROSPECTS OF MINERAL RIDGE. 45 

same general appearance, and even on the outcrop it often requires close scrutiny to 

distinguish them. The alaskite becomes quartzose (both in the mines and on the 

surface), and passes from an even, granular condition to one characterized by large 

and small irregular or elongated blotches and veinlets of quartz, and thus gradually 

to typical quartz veins. Every vein or lens thus far mined or prospected shows, in 

places, mixed with the quartz, considerable feldspar, though in general it is fl'>und 

that with the incoming of feldspar in the ore body the values fall off quickly. The 

auriferous quartz in the mine, in the surface workings, in the Drinkwater tunnel, and 

in the Hickey tunnel often runs off laterally along the drifts into alaskite, chiefly 

pegmatitic. An example of this is found in the east end of the Hickey tunnel workings, as shown in the locality marked x in Pl. VIII. Here a strong quartz vein 

begins to contain scattered 

feldspar to the eastward, 

and farther on the feldspar 

begins to encroach more 

and more upon the quartz, 

until it becomes practically 

a pegmatite, which, however, contains irregular segregated bunches of solid 

quartz up to 2 0\- 3 feet in 

diameter. It is here demonstrated that the pegmatite 

and quartz masses are contemporaneous and are one 

and the same body. Sometimes, however, a stringer 

of quartz can be seen cutting 

across the pegmatite, showing that it was the last mineral to crystallize. This pegmatite consists essentially 

of quartz and feldspar and 

occasionally muscovite, and 

FIG. 5.- Verti.cal sketch section of surface open cut on Drinkwat er ore zone, a 

short distance south of the mouth of the Drinkwater tunnel, showing lenses 

of qua rtz and alaskite. Q, Quartz (ore); A, alaskite (quartzose) ; S, schist 

(altered shaly limestone). 

very rarely biotite. Pyrite, apparently arsenical, occurs in the pegmatite and more 

frequently in the quartz. 

The general conclusion is that in and near these mines a series of fissile shales and 

thin-bedded limestone has been invaded by a very siliceous granitic intrusion, which 

has locally metamorphosed the sediments to schists. The quartz has plainly the 

same origin and nature as the alaskite, both being siliceous phases of a granitic 

magma. Both are intrusive, in lenticular elongated bands, chiefly along certain 

zones in the strata (fig. 5). 

The exact relation between the quartz and alaskite may be understood by 

reference to the microscopic st~dies described under the head of Alaskite (p. 41). It 

is there shown that the crystallization of the intrusive granitic fluid has been slow and 

interrupted, and that the order of crystallization has been the same as that ordinarily 
PLATE XIV. 

ROCK SPECIMEN SHOWING ARRANGEMENT OF QUARTZ AND FELDSPAR IN ALAS KITE DIKE. 

Reproduction of photograph, actual size, of polished specimen (No. 172) of fresh and uncrushed ala~kite from 

a dike in marble in a canyon below the Drinkwater mine c~ee fig. 1). The specimen shows thA full 

width of the dike. ThP minerals arl' almost exclusively quartz and feldspar. N otP the medium-granular 

structure, which locally (as in the uppPr part of the specimen) becomes more or less banded parallel to 

the dike wall, with the separation out of blotches and hands of magmatic quartz. In the lower end of 

the figure the feldspar (light colored) shows idiomorphic outlines against the magmatic quartz which 

runs up the right-hand side of the figure. The area within the rectangle is prPsented enlarged in 

Pl. XV. 

46 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 55 PL. XIV 

ROCK SP ECIM E N SHOWING ARRANGEM ENT OF QUARTZ AND FELDSPAR IN AL ASK ITE DIKE. 
GOLD MINES AND PROSPECTS OF MINERAL RIDGE. 47 

observed in granitic rocks, namely, that the feldspars have crystallized first and the 

quartz last. There has been a great deal of difference, however, in the periods of 

feldspar crystallization, two distinct generations being easily recognized. Complete 

crystallization was evidently accomplished slowly, so that in many places the 

magma became first transformed to a mass of contiguous feldspar crystals whose 

interstices were filled by the residual granitic fluid. From this fluid there was crystallized out quartz, which occupied the interstices and completed the crystallization 

of the alaskite. Gathering together in larger bodies, the quartz formed solid masses, 

veins and lenses, of all sizes, ranging from particles determinable only under the 

microscope to lenses 8 or 10 feet thick and 100 or more feet in lateral extent. Such 

lenses sometimes occupy or follow fractures which were made in the semiconsolidated 

alaskite, or (where the solutions have traveled some little distance from their points 

of origin) they have formed veins in alaskite which was at the time practically 

entirely consolidated. 

Microscopic demonstration of this origin is found by examination of some rocks 

from this mine, as has been already partially referred to. For example, a specimen 

from the Hickey tunnel shows a first generation of crystallization, consisting of fine 

allotriomorphic granular feldspar with quartz, the feldspar consisting of orthoclase, 

albite, and microcline. This first generation has been strained and broken, and the 

rifts are filled with granular or retiform unbroken quartz containing two idiomorphic 

feldspar crystals; one fully contemporaneous with the quartz, the other, though 

entirely inclosed within it, broken, and containing a quartz veinlet, marking it as a 

slightly earlier mineral. Other cases showing the same thing with slight variations 

were observed elsewhere. In the canyon below the Drinkwater mine there was 

examined a dike of alaskite 6 inches in thickness, which is intrusive into marble (see 

fig. 1). Both in the hand specimens of this dike and under the microscope the 

passage is consecutively shown from a moderate-grained uncrushed alaskite to little 

bunches and veinlets of segregated quartz, and even to larger quartz masses. These 

quartz streaks are apt to be elongated parallel to the sides of the dike (Pls. XIV and 

XV). A thin section shows feldspar (mainly orthoclase, with some striated feldspar) 

and quartz in about equal proportions. The feldspar has a definite tendency to 

group itself into thin parallel layers with alternating layers in which quartz is predominant. Thus an original gneissoid structure is obtained. The feldspar crystals 

are idiomorphic to hypidiomorphic; the quartz is allotriomorphic and distinctly later, 

but occurs in grains similar in size to the feldspar crystals. 

INl''LUENCE OF lliORITE ON YALPES. 

The diorite dikes extend along the quartz lenses or cut them, as previously 

stated, but are of distinctly later age. They have sometimes been held to have an 

important connection with the rich ores. On this account the question was examined into carefully by the writer, in company with .Mr. R. 1\1. Geppert, of Denver, 

who was at that time engaged in a general sampling of the mine. 

In the Hickey tunnel, where the diorite is more conspicuous than in the upper 

workings, it was noted that where it forms the wall of the quartz the quartz is 

traversed by parallel cracks for a few inches at its contact with the dike, these 

cracks being also parallel to the contact. Sometimes this cracked zone is a foot or 
PLATE XV. 

ROCK SPECIMEN SHOWING DETAILS OF ARRANGEMENT OF QUARTZ AND FELDSPAR IN 

ALASKITE DIKE. 

Portion of polished specimen of alaskite dike (Pl. XIV) enlarged 3 diarnt>ters by photography and retouched 

to show the rPlative distribution of quartz and feldspar in the rock fabric. The light is feldspar (f); 

the dark, quartz (q). The texture varies from medium granular to fine pegmatitic. 

48 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1'\0. 55 Pl. XV 

ROCI< SPECIMEN SHOWING DETAILS OF ARRANGEMENT OF QUARTZ AND FELDSPAR IN ALASKITE DIKE. 
GOLD MINES AND PROSPECTS OF MINERAL RIDGE. 49 

more thick. Along these cracks there is generally a dark substance which has 

penetrated the quartz from the cracks. The same dark coloring is noticeable in 

the quartz at the contact of the dike. Along such cracks pyrite is also found, sometimes forming only a crust and not filling the crack completely. The origin of the 

pyrite is evident, for the diorite itself is decomposed and richly spotted with pyrite 

which has formed at the expense of the iron silicates in the rock. This pyrite in the 

decomposed diorite, as might be expected, has not been shown to contain important 

values. To test the question as to whether the cracked quartz near the diorite had 

been enriched, a general assay sample of this quartz was taken by the writer and 

Mr. Geppert. This yielded to Mr. Vollmar gold 0.36 ounce; to R. H. Officer, gold 

0.315 ounce, silver 0.475 ounce. As thi,.; sample was from a portion of a quartz 

ore lens, the value indicated is certainly not more than usual-in fact, probably 

somewhat below the average. The writer learned that Mr. Geppert found in another 

locality, as the result of his assays, that such a dark zone of quartz near the diorite 

contact. cracked and containing secondary pyrite, carried only about one-fourth as 

much gold as the unsheeted quartz below. In this case, at least, there was no enrichment, but probably an impoverishment. In other cases this cracked and pyritized 

zone runs higher than the main body of quartz, when it usually carries secondary 

galena, a mineral which is a highly favorable indication of gold values in this mine, 

whether it is of primary or of subsequent origin. In a small subsequent veinlet 

formed along a crevice near the diorite in the Hickey tunnel the writer found that 

the gangue material was mostly coarse calcite, probably derived from the decomposed diorite, with some quartz and green chlorite. The calcite contained considerable contemporaneous pyrite and galena. These occurrences are, however, exceptional, and are of little or no importance in considering the general values of the 

deposits. No diorite occurs in intimate connection with the rich ores which have 

been removed from the upper Drinkwater workings. It has been reported, however, 

that in these older workings the richest ore (now removed) came from near the 

hanging wall. a This report, in connection with the occurrence of richer subsequent 

ore near the hanging wall of the Mary mine (seep. 54) and other facts, suggests that 

these richest ores of the Drinkwater may have also been in part subsequent, though 

not dependent upon the diorites. 

It seems from the facts presented that the fractured 'nes in the quartz, which 

have probably been formed by t!1e intrusion of the dinr e, have served simply as 

channels along which the original values in the quartz have been somewhat concentrated in some places at the expense of others. 

VALUES IN WALL ROCKS. 

Values in C!laskite.-From a crosscut into the foot wall ~eneath the stopes in 

the upper Drinkwater tunnel workings a number of average samples were taken for 

assay by Mr. R. M. Geppert, and six of these were assayed by Mr. F. A. Vollmar. 

They were mostly solid alaskite, with some mixed alaskite and schist. Three of 

these samples contained 0.01 ounce of gold, two contained 0.03 ounce, and one contained 0.10 ounce. 

In another crosscut from the Drinkwater stopes, the Hanchett crosscut, 

samples were take• from alaskite containing some small bunches of quartz. Four of 

a Report of the Mineralogist of the State of Nevada [Dr. A. E. White] for 1869 and 1870; published 1871. 

13002-No. 55-06-4 
50 ORE DEPOSI'rS OF SILVER PEAK QUADRANGLE, NEVADA. 

these samples contained a trace of gold, one contained 0.05 ounce, one contained 

0.06 ounce, and one showed no gold whatever. 

At the lower end of the winze shown in Pl. IX, locality a, a general sample was 

taken of the harder portions of the alaskite pegmatite. This yielded toR. H. Officer 

& Co., gold, trace; silver, 0.025 ounce. 

A series of general samples were taken by the writer and Mr. Geppert in the 

Hickey tunnel. At the point marked a in PI. VIII the rock is a hard, fresh 

alaskite. On one side of the drift there is no quartz and the rock is shown by the 

microscope to consist of quartz and feldspar only, the texture varying from granitic 

to fine pegmatitic. The feldspar, which is largely finely striated, has an idiomorphic tendency, showing a crystallization earlier than that of quartz. A general 

sample of this yielded F. A. Vollmar, gold, trace; R. H. Officer, gold, 0.005 oz.; silver, 

0.025 oz. On the other side of the drift in the same rock are small bunches of segregated quartz, often feldspathic, containing considerable pyrite and some galena, 

plainly contemporaneous and inclosed in good-sized separate bunches, up to the size 

of hazelnuts, in unbroken vitreous quartz. This locality is marked b in PI. VIII. 

One such small quartz bunch was highly pyritiferous and contained only a few,. 

pounds in all. This bunch gave Mr. F. A. Vollmar, gold, 4.15 oz.; R. H. Officer, gold, 

3.810 oz.; silver, 0.840 oz. 

At locality c, PI. VIII, the rock is hard alaskite, consisting of quartz, orthoclase 

and striated feldspar. The microscope shows that it has undergone a very slight 

crushing. A general sample gave F. A .. Vollmar, gold, trace; R. H. Officer, gold, 

trace; silver, 0.025 oz. At locality d, Pl. VIII, the rock is pegmatitic quartz, a sample 

of which yielded R. H. Officer, gold, trace; silver, 0.015 oz. A general sample of the less 

quartzose pegmatite in the same place gave gold, 0.005 oz.; silver, 0.017 oz. At locality e, PI. VIII, the rock is alaskite with some small segregated quartz vejns. Exceptionally some biotite is present; otherwise the rock contains quartz, fresh orthoclase, 

and microcline. A general sample of this gave F. A. Vollmar, gold, 0.0025 oz.: R. H. 

Officer, gold, trace; silver, 0.10 oz. 

In the adit portion of the Hickey tunnel workings, at locality, e Pl. X, the rock 

is alaskite, generally coarse, with some small lenses of hard quartz and some layers 

of schist. A general sample gave F. A. Vollmar, gold, 0.06 oz.; R. H. Officer, gold, 

0.06 oz.; silver, 0.095 oz. At locality g, on the outer edge of a large alaskite mass, a. 

general sample gave F. A. Vollmar, gold, trace; R. H. Officer, gold, trace; silver, 

0.020 oz. 

Values in limestone schist.-In the Hickey tunnel adit, locality b, Pl. X, a 

general assay was taken of limestone slightly altered, with quartz seams. This 

yielded F. A. Vollmar, gold, 0.0025 oz.; R. H. Officer, gold, trace; silver, 0.020 oz. Farther in the tunnel, at locality d, PI. X, is a rather massive bedded, altered limestone, 

consisting under the microscope of fine crystalline calcite with some secondary 

hornblende, epidote, quartz, and feldspar. A general sample gave F. A. Vollmar, 

gold, 0.007 5 oz.; R. H. Officer, gold, 0.020 oz.; silver, 0.045 oz. Still farther in the 

tunnel, overlying the main alaskite mass in which the Hickey tunnel lateral workings lie, locality f, Pl. X, is a fine-grained limestone, shown by the microscope to contain scattered grains of originally detrital quartz. Of this a gtneral sample gave 

F. A. Vollmar, gold, trace; R. H. Officer, gold, trace; silver, 0.030 oz. 
• 

GOLD MINES AND PROSPECTS OF MINERAL RIDGE. 51 

FOLOJNG AND FAULTING. 

Around the Drinkwater mine group the thin-bedded and schistose limestone and 

slates are folded and contorted on a minor scale, but have a general northeasterly 

dip. No large folds are noticeable. Some of this minor folding is probably subsequent in part to the intrusion of alaskite and quartz, and the disturbance may in 

general have accompanied the intrusion. Local reversed dips in the quartz lenses 

may b() due to folding. Faulting of alask1te and quartz on a small scale may be 

seen m the outcrops (fig. 6). Small faults are also determinable underground, as 

shown in the east end of the Hickey tunnel workings (Pl. VIII), where quartz and 

alaskite are displaced. The slates have in many places become schistose and contain 

numerous laminre of quartz and alaskite, and the resultant rock is usually contorted. 

In many cases these contorted laminre, representing the siliceous intrusion, may be 

interpreted as veinlets which have followed the laminre of the folded slate, but some 

of the contortions hardly admit of this 

explanation and are probably subsequent to the intrusion, as is indicated 

by the accompanying minute faulting which displaces the quartz-alaskite 

sheets. 

CRUSHING. 

All the rocks under discussion, including the altered limestone and slate 

and the alaskite, quartz, and diorite, 

are frequently more or less crushed, as 

has been defmitely determined by 

microscopic study. On the other hand, 

much of the material has not been 

crushed. All the specimens used to 

determine the composition, texture, 

0 2 feet 

I 

FIG. 6.-Sketch of vertical outcrop, Drinkwater Canyon, showing dying out of fault. 

and structure of the alaskite and quartz in the foregoing descriptions were taken from 

uncrushed rock. The amount of crushing varies from mere straining to complete 

granulation. 

Remarkably little crystallization or metamorphism followed this crushing, and 

no subsequent vein action can be detected. In granulated alaskite the original 

minerals-chiefly quartz, orthoclase, and microcline-are as fresh as in the uncrushed 

specimens. -Occasionally a little sericite has been developed along strong fractures, 

and even a little chlorite. Calcite in small veinlets is of more frequent occurrence 

and has evidently been transferred from the limestone to the crevices in the crushed 

alaskite. Where the quartz has been crushed, microscopic study usually shows 

that the pyrite also has been crushed. It is therefore beyond doubt that the 

mineralization preceded the crushing. 

SUBSEQUENT OREA. 

No decided enrichment of the ores by oxidation can be established. It is true 

that, so far as can be determined, the ores in the upper tunnel seem to have been 

locally richer than any found in the lower tunnel, but, as has been already noted, this 
• 

52 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA, 

localization and enrichment has no evident connection with the surface, but takes 

place irregularly along the surface and is probably an original difference. The character of the ore affords no ground for supposing any great concentration by surface 

waters, since the values are contained in finely disseminated gold and a small 

quantity of auriferous sulphides scattered through a mass of vitreous quartz. The 

minerals containing these values are not easily reached or attacked to any great 

extent by percolating waters. The quartz bodies are traversed by strong cross fractures, but no shoots corresponding to these are known, indicating that waters circulating along these subsequent fractures have had very little effect in redistributing values. 

In the upper workings small specimens of cerussite (lead carbonate) are reported, 

evidently the result of the alteration of galena by surface waters. 

WESTERN SOLDIER. 

As shown on the map, theW estern Soldier mine lies eaet of the Drinkwater, but 

on the same zone of lenses. The overlapping lenses are graphically shown in fig. 7. 

Each one averages 5 or 6 feet in maximum thickness. 

N s 

Homestake Western Soldier 

-~-

----- -- ~ ~-- ~--====--- --- ~--- ---- ---- --- ---- - ----~ ~ -- - --------- --------------- -: ~ a ~ ===- - ----------- ---- ___.- ~ ------ ------------- ----- __- -------------;:f caf"'yofl 

------------- - - -- - - - ----- Bottom 

0 100 200 300 400 soo feet L-----~----.-L------L-----~----__j 

- FIG. 7.-Rough vertical sketch of east wall of second canyon east of Drinkwater mine, showing the Drinkwater zone or quart?. 

lenses. The position of various tunnels of the IIomestake and Western Soldier mines is indicated; the number and position of the quartz lenses is approximately given. 1 

The mine is credited with a production of 10,000 tons, valued at $20 to $22 per 

ton, making a total production of about $200,000. 

'One of the ore bodies in this property is said to have been the richest in the district. Specimens taken by the writer and examined under the microscope show 

galena, oxidized pyrite, and free gold, the latter separated entirely from the o:;cides 

and sulphides and isolated in small particles in the quartz. These ores appear to be 

primary and contemporaneous with the quartz. The quartz passes into a feldspathic 

quartz containing orthoclase, and this passes into a quartz-orthoclase rock or alaskite. The alaskite contains quartz, orthoclase, microcline, and probably albite, and 

a specimen studied microscopically showed that the orthoclase was much altered to 

fine muscovite, the albite considerably, and the microcline not at all. 

These rocks as seen under the microscope are considerably crushed. In the 

specimen mentioned above the microcline, although fresh and clear, is broken, showing that the alteration to fine muscovite preceded the crushing. In one crushed 

specimen uncrushed and therefore probably secondary pyrite was observed. 
GOLD MINES AND PROSPECTS OF MINERAL RIDGE. 53 

• Diorite dikes are numerous, and are generally parallel to the quartz lenses, 

' though occasionally they cut across them or send tongues into them. No evidence 

of enrichment of the quartz near these diorite dikes was found. The quartz near 

the diorite seems to be in no way or degree different in value from that which is not 

near it. 

One or two minor faults were observed in the dikes. At one place a diorite dike 

' crosscutting a quartz lens is displaced by a slight reversed fault. At another place 

a small normal fault is seen. 

HOMESTAKE . 

.Ks shown in fig, 7, the Homestake is the continuation on the same zone as the 

Western Soldier, being a portion lying farther down the canyon. It has a credited 

·production of $60,000. Fig. 8 shows a general section at the lowest outcrop of the 

Homestake, where the ore has the usual characteristics and is closely associated with 

siliceous alaskite containing quartz veinlets. Into this siliceous alaskite it is distinctly transitional at various places. Farther up the hill, at locality 1, fig. 7, and 

at locality 2, a transition from the quartz lens into alaskite was also observed. At 

locality 1 a thin section of the feldspathic rock proves to consist essentially of coarse 

crystalline microcline, strained but unbroken and very fresh and clear. This 

o 5 10 zo 30 feet 

"FIG. 8.-Dia~:rammatic sketch of section at lowest workings of Homestake mines, showing ore lenses and attendant sheets 

of alaskite intrusive into thin-bedded altered limestone. 

incloses numerous irregular grains of a striated feldspar of high double refraction. 

In this microcline mass the cracks caused by breaking. are filled with fine granular 

quartz and some orthoclase, with opaque carbonates and some gray-black metallic 

minerals. At locality 2 also the feldspathic rocks consist essentially of coarse 

microcline with some quartz. This chiefly microcline rock has been considerably 

broken and has been pierced by many small reticulating veinlets of quartz which 

have penetrated the microcline in every direction. (Pl. XIII, A.) 

In another thin section of alaskite studied the rock has undergone crushing since 

its final consolidation. 

At locality 1, fig. 7, a 6-foot dike of relatively coarse diorite cuts nearly perpendicularly across a quartz lens at right angles to it without displacing it. At locality 

' 
54 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

2 diorite holds the same relation to the vein. No enrichment is known to occur at 

the contact of the diorite and quartz in either case. Near the contact of the diorite 

the quartz happens to be very barren. 

MARY. 

As shown on the map, the Mary mine lies near the Homestake and Western 

Soldier, and its workings are on the same zone of lenses as the above-mentioned 

mines. The Homestake and Western Soldier operate from the outcrops of the ore 

lenses on the side of the canyon, while the Mary reaches the lens zone by two tunnels 

running southwestward. Of these the lower one is the longest and was the means of 

working the mine at the time of the writer's visit. This tunnel runs in 450 feet to the 

zone and is 1,100 feet long in all (fig. 9). 

The ore is in perfectly characteristic overlapping quartz lenses. Several parallel 

lenses may be on the same level. The lenses are associated with alaskite and run 

into this rock laterally, which is a fact known and recognized by the foreman of the 

mine. In the upper workings the ore was a free gold ore, carrying, it is stated, from 

$12 to $15 to the ton, and was free milling, with few sulphides. In the lower portions of the mine there is a considerable amount of sulphides, mostly pyrite, with 

some galena. It is of higher grade than that in the upper levels, but the values are 

harder to extract. The ore is milled and then concentrated, the concentrates being 

shipped for smelting and the tailings cyanided. The ore being mined at the time of 

the writer's visit was stated to assay about $26, of which milling extracted only 

about 54 per cent. 

The sulphides in the lower workings are mainly in cracks in the quartz and are 

evidently subsequent--that is, they have crystallized since the crystallization of 

the quartz lenses. They evoo coat crevices in siliceous limestone partings in the 

quartz. The cracks in general run parallel to the upper wall of the lens near which 

they occur. In the lowest workings visited by the writer, in a winze 130 feet on an 

incline below the main tunnel level, this subsequent sulphide ore was about 5 feet 

thick next to the hanging wall, and the whole was said to assay $84. Beneath this 

was about 8 or 10 feet of poorer quartz, which, however, contained mor~free gold, 

though less sulphides. Throughout this mine it is said that the hanging wall portion 

of the lenses is better than the foot-wall portions, for while rich bunches occur near 

the foot wall they are.not numerous. 

The walls of the lenses consist both of alaskite and of limestone, the latter blue, 

dense, and slightly carbonaceous. Beneath the vein in the main crosscut tunnel is 

some limestone schist, and below this there is alaskite continuously to the breast. 

Above the vein zone the tunnel passes through limestone and alaskite alternately 

(fig. 9). 

The alaskite in these workings is typically a pure quartz-feldspar rock, often 

pegmatitic. Muscovite occurs occasionally in the pegmatitic variety, and rarely 

biotite is present. Biotite also occasionally occurs in the granular alaskite, forming 

a granitic phase. 

Specimens of the alaskite were examined microscopically. One specimen 

consists partly of coarse granular quartz, and partly of feldspar of similar grain, 

chiefly orthoclase. The quartz is slightly subsequent to the feldspar and locally 

intrusive into it, as previously noted in other localities, yet is an integral part of the 
GOLD MINES AND PRORPECTS OF MINERAL RIDGE. 55 

rock. In another specimen having the same composition the quartz was more 

-definitely contemporaneous, but was here and there segregated into very small, irregular bunches. Many of these bunches are elongated and so approach a vein-like form. 

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In this specimen muscovite is present, varying from very fine (sericitic) to small 

separate crystals like the characteristic muscovite of granitic rocks. The complete 

gradation indiGates a common origin. The larger grains are plainly an original rock 

• 
56 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

constituent and the finer ones are probably the same, and yet the latter occur in 

isolated sheaves and bunches in otherwise fresh feldspar, sometimes completely 

replacing the latter. A process of magmatic alteration during crystallization is thus 

indicated. 

Another specimen shows a similar composition, being mainly quartz and feldspar, but contains biotite in small irregularly scattered crystals. Chlorite is frequent 

in this section, being probably an alteration product of biotite. Apatite, zircon, 

pyrite, occasional muscovite, and a little calcite occur, together with magnetite and 

probably ilmenite. The pyrite is original and is more abundant than the iron oxides. 

Pyrite, muscovite, and calcite in one case appear intergrown and contemporaneous. 

Another specimen of this biotitiephase of alaskite shows more biotite than the first 

specimen, and in larger crystals, with some chlorite as an alteration product. The 

feldspar qonsists of microcline, orthoclase, and oligoclase-albite. Pyrite and magnetite (ilmenite?), both original, are extremely common, and are associated and intergrown with biotite and with each other. Sphene is common; and cloudy leucoxenic 

crystals often surround the sphene and the magnetite or ilmenite. Small apatite 

crystals are common, as well as long, greenish needles of an undetermined mineral 

having high single and low double refraction. Muscovite is scattered in small crystals, much smaller than those of the biotite or any of the other larger minerals. It 

occurs in small isolated crystals included in the large feldspars, but is strictly original 

and contemporaneous with the feldspar. The biotite has a tendency to uniform 

orientation, though not always in the same direction, but in curves. There is an 

irregular arrangement of darker and lighter portions in different parts of the slide, 

and quartz is frequently segregated into bunches of allotriomorphic grains. Tourmaline was noted in this rock. 

No diorite was seen in the workings near the vein zone, so that the subsequent 

ore described above probably has no connection with this rock. One diorite dike was 

encountered in the adit tunnel. 

A little minor faulting was observed and there has probably been some broad 

folding which may have included the veins. 

Although all the specimens of alaskite described above are of uncrushed rock, 

some other portions have been considerably crushed, as shown by microscopic study. 

A specimen taken from the vein zone in the mine was of the ordinary type, consisting 

of microcline, orthoclase, albite, and quartz, but was entirely granulated by crushing. 

A specimen collected on the hill above the Mary mine was obtained from one of the 

most altered phases of schist seen in the district. The microscope shows it to be a 

crushed muscovite-granite. It contains quartz, coarse muscovite, and chlorite, with 

rutile (sagenite) needles, probably residual from biotite crystals. These minerals are 

all antecedent to the crushing. Minerals subsequent to the crushing consist of fine 

muscovite (sericite), oxidized pyrite, and quartz in tiny veinlets. 

APRIL. 

As the map shows, the April mine is situated east of the Homestake and on the 

same zone of lenses. The geology is similar in all details to that of the mines already 

described. Quartz and alaskite lenses occur in a thin-bedded limestone which is 

often schistose. The ore is generally accompanied by some diorite, usually an 
GOLD :MINES .AND PROSPECTS OF MINERAL RIDGE. 57 

intercalated sheet. The mine is said to have produced 200 tons of ore having an 

average value of $50 to the ton. The ore was free milling and was worked in 1892-93 

in Chiatovich's mill at Silver Peak. 

LAST CHANCE. 

The Last Chance lies east of the April and is the easternmost mine on the Drinkwater zone of lenses. Openings show a strong lens of quartz associated with pegmatitic quartz-feldspar veins in alaskite. The alaskite is sometimes crushed and 

contains secondary sericite, with infiltrated calcite. Besides alaskite, limestonedark, usually thin-bedded, and siliceous-frequently forms the wall rock. 

Greenstone or altered diorite occurs in a sheet a few inches to over a foot in 

thickness, which runs through the ore or along one of its walls. The rock is completely altered from its original form to calcite, quartz, kaolin, etc. It contains 

included fragments of quartz, some of them angular in shape. Along the contact of 

the greenstone dike with the quartz there is a strongly marked band of galena, with 

accompanying iron rust showing original pyrite. This galena has formed in part in 

the altered dike as well as in the quartz. Although this band is only a fraction of an 

inch in thickness there is no question as to its secondary nature. The ore containing 

galena in this mine as in others is usually relatively rich. The rest of the quartz near 

the dike is also usually good. 

Small calcite veins, irregular and nonpersistent, occur in the greenstone, from 

which they have probably been derived by lateral secretion. 

FRANK NO.2. 

The Frank No. 2 properties comprise a string of several small openings running 

in a north and south direction at the head of Echo Canyon. The quartz lenses here 

are probably on the same zone as those of the Drinkwater mine. The lenses lie flat, 

or approximately so, conforming with the general flattening of the limestone schist 

formation toward the south. The quartz bodies are of the ordinary type previously 

described, and make up lenses of various dimensions. 

The quartz is associated with alaskite, which forms the usual country rock. A 

part of this alaskite is fresh and uncrushed and contains segregated bunches and veins 

of quartz. In places the main lens of quartz passes by transition along its margin 

into the alaskite country rock. Such quartz carries '::alues, general assays from $3 to 

$14 being reported. Some of the bunches of segregated quartz within the alaskite 

show galena and carry values. Some of the galena sits upon free crystals of quartz, 

w~ich line tiny druses. 

A specimen of typical fresh and uncrushed alaskite, examined microscopically, 

shows a general granitic structure. It shows also two distinct generations of crystals. 

The first generation is represented by large hypidiomorphic grains of orthoclase and 

some of andesine oligoclase. Both, the orthoclase especially, are filled with muscovite fibers, in some places of relatively coarse grain, though still microscopic. The 

intensification of the amount and size of the muscovite along the edges of the feldspar crystals and along certain lines, evidently fractures in the crystals, shows the 

muscovite to be due to a process of alteration of the feldspar. The very irregular 
58 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

shapes of the coarse feldspar grains sht,w that they were formed in place and were not 

caught up and included by the subsequently crystallized rock. This subsequently 

crystallized rock is represented by the second gen(!ration. It consists of perfectly 

fresh and unbroken quartz, orthoclas~, some microcline, and some striated feldspar. 

These minerals are intercrystallizecl and contemporaneous. The quartz is relatively 

most abundant. It fills the interstices between the feldspar grains, intrudes, on a 

microscopic scale, feldspar grains of the earlier generation containing muscovite, 

and fills cracks caused by the occasional breaking of these. For all this, it is ordinary 

granitic quartz. The fresh feldspar sometimes invades the muscovitized feldspar of 

the older generation. Clear orthoclase incloses isolated idiomorphic small crystals 

of the older muscovitized orthoclase and also similar crystals of muscovitized 

striated feldspar. The coarser muscovite grains along the edges of the older feldspar 

are in some places intergrown with the edges of the quartz. The fresh feldspar of the 

second generation sometimes incloses quartz, sometimes is traversed by it. A single 

tiny quartz veinlet cuts straight across the slide. This is composed of quartz grains 

of the same size as the ordinary grains filling the spaces between the feldspar, and is 

actually everywhere connected with these grains. Zircon was observed in the 

younger feldspar and quartz. 

The following history of the formqtion of this rock is therefore indicated: (1) 

Crystallization of orthoclase and andesine-oligoclase into a mass of adjacent crystals 

nearly filling the magmatic fluid; (2) alteration of the feldspar in part to fine mus,-

covite, especially along the edges; (3) deposition of predominant quartz, orthoclase, 

relatively less microcline, and still less striated feldspar and tiny crystals of zircon, in 

the interstices. The movements of the fluid from which the second generation of 

crystals formed were sufficient to rupture the older crystals and to make tiny crevices 

in which the new minerals crystallized. Along a larger crack ·a quartz veinlet formed. 

On the west wall of Echo Canyon, about 20 feet below the northernmost open cut 

on ore of the Frank No.2, free gold occurs in unaltered alaskite pegmatite, which 

here forms a great mass constituting the whole country rock. This rock is composed 

essentially of quartz and feldspar, with some muscovite. At the place mentioned 

free gold is disseminated through the rock in small specks. In some places the gold 

is plainly derived from oxidized pyrite; in others it appears in small grains that are 

quite free from iron rust. It occurs principally in the quartz of the pegmatite but 

is also embedded in fresh feldspar. The area where this gold has been found is only 

about 3 yards in diameter and has no special form or other characteristic to distinguish it from the surrounding rock, which, so far as known, does not contain gold. 

A specimen of the auriferous pegmatite examined microscopically proves to consist 

of quartz, orthoclase, and microcline, all perfectly fresh. The rock has been cracked 

and in part crushed, although the crushed feldspar remains quite fresh. No gold 

was observed in the thin section. 

Schist (probably altered thin-bedded limestone) also forms in places the waH of 

the Frank No.2. Into this schist both quartz and alaskite are alike intrusive, in the 

form of lenses. 

Greenstone or altered diorite is the latest rock connected with the ores. A dike of 

this rock 3 or 4 feet thick follows the ore zone, forking and reuniting so as often to cut 

.out a portion of the vein, and sometimes splitting so as to leave a fragment of the 

• 
GOLD MINES AND PROSPECTS OF MINERAL lUDGE. 59 

vein included (fig. 10). The vein fragments in such a position seem to be richer than 

the average. The ore shows sulphides, consisting of galena and pyrite, filling parallel 

cracks. • The miscl'oscope shows also the presence of calcite in these cracks. Such ore 

is undoubtedly subsequent. All the ore milled has been of this class. The galena 

here is the best indication of good values, which are in gold, accompanied in places by 

a very little silver. 

Some portions of the alaskite are greatly crushed, the crushing being accompanied by the development of sericite; other portions are slightly crushed; while still 

others are perfectly intact. From an examination of outcrops it appears likely that 

this difference is due not so much to localization of the crushing stresses as to slightly 

different age of the different alaskites. Crushed alaskite and that which has undergone no stress occur in immediate contact and seem even to be transitional into each 

other. It is probable that some crushing occurred during the crystallization of this 

~ Scale of feet 0 5 10 15 1~1 Alas kite Quartz 

FIG. 10.- Vertical sketch section of open cut in northeast workings Frank No.2. 

rock, and that the rock which was first formed was intruded by slightly later 

material of the same character. The diorite as a rule is altered but uncrushed, and 

the subsequent ore also is uncrushed. 

Some slight faulting occurred subsequent to the dibrite intrusions. 

COLUMBUS. 

The Columbus is a small mine or prospect separated by a little valley from the 

Frank No.2. The valley is the continuation of the upper end of Echo Canyon but 

is not deeply cut. The Columbus is probably on the same zone as the Frank No.2, 

the intervening portion having been r~moved by the erosion of the valley. The 

mine is said to have produced 200 tons of ore having an estimated value of $15 per 

ton. The ore was milled in a small stamp mill at Valcalde Springs. 

The quartz which constitutes the ore occurs in flat-lying lenses, which pass into 

• 
/ 

60 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

quartz-feldspar rock (alaskite) along the edges. Limestone schist also forms the 

walls in part. 

The alaskite wall rock contains in places abundant quartz segregations and veinlets. Smaller bodies of alaskite are of lenticular form and are surrounded by schist 

in the same manner as the smaller quartz lenses. 

Diorite is found near the ore, sometimes as a foot wall to the quartz lenses, or at 

some distance away from it, but generally parallel to the lenses and conforming to the 

general attitude of the schist. 

There has been considerable crushing of the ore and the country rock. A specimen of the quartz viewed under the microscope is seen to be thoroughly crushed. It 

contains oxidized pyrite, which is uncrushed and therefore subsequent to the movement, and also fine granular calcite and a green amorphous substance, the latter two 

probably infiltrated. 

SOLBERY. 

The Solbery is a small mine, hardly more than a prospect, belonging to the 

., Messrs. Val cal de and situated at the extreme head of New York Canyon, on the west 

branch. According to reports it has produced 100 tons of ore, valued at $20, making 

the production $2,000. At the mine opening, where there is a short tunnel and stope, 

the ore is quartz, 2 feet in thickness. It contains considerable feldspar. A specimen 

examined under the microscope is seen to be coarse quartz, with considerable coarse 

fresh orthoclase and microcline in some areas. In the outcrop the quartz seems 

slightly later than the quartz-feldspar rock or alaskite, but the vein passes into alaskite and is lost. Besides this vein or lens there are three or more parallel lenses, 100 

to 150 feet apart. They have been worked to only a slight extent. 

In the chief opening above mentioned the hanging wall of the quartz is alaskite, 

siliceous, and quartzose. A specimen examined microscopically was found to consist of coarse quartz, orthoclase, and striated feldspar, the feldspar being slightly 

muscovitized. These coarser crystals are cut by veinlets of finer quartz, with some 

fresh feldspar, and the veinlets are slightly faulted microscopically. The foot wall 

consists of 3 feet of green schist, with alaskite lying below it. The original nature 

of the schist is not certain. The microscope shows it to consist of quartz, sericite, 

and calcite, with subsequent uncrushed pyrite, now completely oxidized. The other 

parallel lenses mentioned have siliceous alaskite for both walls. 

Both alaskite and quartz are locally strained and somewhat crushed. This 

crushing, as usual, has had slight metamorphic effect, the crushed feldspar remaining 

fresh. Some sericite has been developed as a consequence of the crushing, and subsequent pyrite was noticed both in the quartz and in the walls. 

RED LIGHT. 

The locality of the small mine known as the Red Light is shown on the map. It 

is the property of Mr. John Chiatovich. Work was begun on the mine in the spring 

of 1888 and it produced about 400 tons, which were worked in Mr. Chiatovich's mill 

at Silver Peak. The first 80 tons, it is said, milled $25 to the ton, the rest about $20. 

The property is mainly opened up at a single locality, by irregular fiat drifts and 

stopes on quartz, and by a shaft 35 feet deep. The quartz constitutes the ore and 
GOLD MINES AND PROSPECTS OF MINERAL RIDGE. 61 

occurs in the form of several overlapping lenses. A very little copper pyrite was 

noticed in the quartz. The general dip of the lenses is slightly east. When it is followed in from the surface along the vein, on the drifts and stopes, the quartz is 

found to pinch from 4 feet to 1 inch on the west wall of the drift; then it thickens 

again and at the face becomes very feldspathic. On the east wall of the drift, a few 

feet away from the west wall, the vein pinches out entirely long before reaching the 

breast, the limestone schist converging from both walls and meeting. 

Limestone and limestone schist constitute the principal wall rock. Some of the 

rock is identifiable under the microscope as a kneaded limestone, somewhat carbonaceous and containing broken quartz veinlets and subsequent unbroken pyrite. 

In this limestone schist there are lenses of alaskite as well as of quartz. Some of the 

schist is also apparently a sheared alaskite, as near as can be judged from the 

microscopic exammation. 

The first 80 tons of somewhat richer ore noted above were taken from the outcrop of the quartz lens. This is important in considering the effect of weathering 

and oxidation on original values. · 

SODA. 

The Soda daim is hardly opened up and is little more than a prospect. It contains small lenses of quartz, each several inches thick, embedded in limestone schist. 

The lenses strike north and south, and dip eastward with the formation, at an angle of 

25°. The best streaks of ore are said to assay $40. 

MISSOURI. 

Only a little work has been done on the Missouri prospect. It has been developd 

by several inclines and open cuts along the strike and by one tunnel. It has not been 

worked for about twenty years, and the period during which it was operated is uncertain. At the main opening, the only place where any stoping has been done, there is 

a quartz lens having a maximum thickness of 5 feet, which dwindles to 18 inches a 

short distance downward. So far as seen the vein is free from feldspar. 

The wall rock is a schistose altered limy slate containing lenses of alaskite and 

alaskite-quartz. a 

A thin section of the alaskite shows some interesting features. Two generations 

of crystals are observable. The older generation is represented by coarse feldspar, 

chiefly orthoclase, with some striated feldspar. These feldspars have been fractured 

and cemented by veinlets of quartz intergrown with contemporaneous, smaller, but 

still good-sized f',rystals of feldspar, of the same species apparently as the older 

crystals. The younger feldspar mostly grows out from the edge of the older crystals, 

but is differently oriented. Many of the smaller fresh feldspar crystals are included 

in the greatly preponderating quartz. 

A lens of harder rock, which is included in the schist and whose shape is probably 

due to crushing, proves on microscopic examination to be greenstone. It is completely altered and consists of a mixture of ~alcite, muscovite, and quartz, with 

pyrite, chlorite, and other decomposition products. 

A slight fault displaces the vein and the inclosing rocks a few feet. 

"This term is used for quartz-feldspar rock containing so much quartz that it is a transitional phase between typical 

alask!te and typical quartz. 
r 

) 

) 

/ 

I 62 ORE ~ITS OF SILVER PEAK QUADRANGLE, NEVADA. 

GOLDEN EAGLE. 

The workings on the Golden Eagle consist of open cuts and short tunnels made 

at various places for 200 or 300 feet along the west face of a steep canyon and near 

the bottom. These openings are on a strong line of quartz lenses which in general 

strike N. 15° W. and dip 10° SW. In places the quartz is as much as 5 feet thick, 

but it always pinches out and is succeeded by other lenses. One tunnel, which 

started on a 2-foot vein of quartz, continued only 40 feet to a point where the lens 

pinched out and disappeared. 

This property was located in 1875 and has since been abandoned and relocated 

several times. In 1900 Bonifacio Aguilar, operating a lease from H. W. Barton, 

took out about 30 tons of ore valued at $30 a ton, and worked it in an arastra at 

Coyote Springs. This is the only production with which the mine is credited. The 

rest of the ore is said not to be so rich, an average value of about $18 being reported. 

Some of the quartz lenses 

.,;,.,..,.,...,...,....""""'.,.,..,,...,...,...,..,=-="""""'==-==-=...,..."='=-==-=::!1N are free from feldspar; othFIG. H.- Vertical sketch section of open cnt of Golden Eagle prospect. A, Siliceous alas kite country rock; AA, siliceous nlaskite, principal ore body; Q, 

quartz {barren); S, Schist (altered shaly limestone). 

ers, again, contain so much 

as to be classed as alaski tequartz. The ore lens from 

which the production given 

above was taken is of the 

latter class (see fig. 11). It 

contains small streaks or 

veinlets of quartz, sometimes distinct and sometimes 

grading into feldspathic 

rock. Such rock contains 

scattered pyrites and galena, 

plainly conte!llporaneous in 

origin with the rest of the 

rock. A typical specimen 

from this ore lens shows two 

generations of crystals. The first is coarse orthoclase. This has been considerably 

broken, and fine muscovite has been developed along the crushed zone. The 

feldspar has been cemented by crystalline quartz. A specimen of the ore containing 

pyrite and galena, taken from the pile which had been sorted out for shipment, is of 

practically the same character as the specimen previously described, but in this case 

the quartz of the sec'ond generation is intercrystallized with fresh orthoclase. In 

places the subsequent feldspar cements a whole crevice in the older feldspar, excluding the quartz of the second generation. 

The walls of the quartz lens are generally schist, containing small lenses of 

alaskite and quartz. Heavy masses of alaskite overlie and underlie these schists. 

In this locality there are a number of diorite or greenstone dikes, both intercalated in the schist and crosscutting it, but they have no connection with the ore. 

In one place an intercalated sheet of such greenstone forms the hanging wall of the 
GOLD MINES AND PROSPECTS OF MINERAL RIDGE. 63 

quartz lens. In this greenstone there are some secondary veins of small size, 

containing quartz and ferruginous calcite, both cutting across the greenstone sheet . 

and running along its upper contact. 

Some specimens of alaskite show crushing subsequent to all crystallization, 

with the development of sericite. 

ESMERALDA. 

The Esmeralda prospect has been opened by a cut 35 feet long, which shows 

moderate-sized lenses of alaskite and quartz in stratified limestone and shaly schists. 

Fifteen feet above the lens zone is a bed of thin-bedded limestone shale which is 

comparatively little altered. 

This may be on the same 

lens zone as the Golden Eagle, 

for quartz can be traced most 

of the distance between the 

two prospects. The strike of 

the beds and vein is N. 15° 

W., the dip 25° NE. The 

quartz contains disseminated 

galena and pyrite, both original. Three or four tons of 

ore taken from the prospect 

were packed on a man's back 

to Tarantula Springs, where it 

is said to have milled $100 tu 

the ton, but no more of this 

kind was found. 

CRESCENT. 

· The Crescent mine is located, as shown on the map, 

on the southwest side of this 

mineral district. It was 

worked desultorily from 1887 

to 1893. Between 200 and 

N 

~ShaFt 

9 Approximate scale of feet 

IC)O 200 390 

FIG. 12. -Sketch on horizontal plan showing outcrop of Crescent lens zone. 

300 tons of ore, valued at $10 to $12'a ton, were extracted and were milled at Tarantula Springs. A mining engineer who has sampled the remaining ore states that 

it averages $12 or $13. The property has been opened up chiefly by a short tunnel 

and a shallow shaft. , 

The geology is exactly like that of the similar properties previously described. 

The so-called vein is a zone of aligned lenses. The outcrop of this zone, as the 

name indicates, is crescentic, following around the edge of a small hill. The cause 

of this curved outcrop is that the vein is flat, with a slightly scoop-shaped depression 

(fig. 12). The strike is east-northeast, the dip southeast, but the latter is locally 

reversed. 
64 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

The solid quartz in the lens zone is about 7 feet thick in its strongest or southern 

portion, but changes rapidly at the other or northeast end to separate smaller lenses. 

At the tunnel near where the ore has been stoped some primary galena was noticed, 

and here the ore is richer than at the other end, where it is thicker, but barren and 

white. · 

The quartz lenses are accompanied intimately by alaskite and by rocks which 

show various gradations between alaskite al'ld quartz. One specimen of this alaskite 

shows, as usual in this rock, two generations, the first consisting of quartz, orthoclase, 

and oligoclase-albite. These have been somewhat broken, strained, and penetrated 

by a second generation consisting of the same minerals as the first, namely, orthoclase, oligoclase-albite, and quartz. The quartz and feldspar of the later generation 

are intercrystallized and contemporaneous, though sometimes small idiomorphic 

crystals of the feldspar. are included in the quartz. Among these crystals albite and 

orthoclase were recognized. The feldspar of the first generation, both the orthoclase and the oligoclase-albite, is partly altered to scattered blades of fine muscovite, 

especially along the edges, while the feldspar of the second generation is clear. The 

younger generation of minerals forms irregular veinlets, sometimes all quartz, sometimes all feldspar; the latter can often be recognized as younger only on account of 

the contrast produced by the muscovitization of the older feldspar. This younger 

material also fills spaces between the larger orthoclase crystals or penetrates these 

crystals, sometimes appearing as isolated grains in the section. On the walls of 

vein-like channels the older orthoclase has been added to by clear orthoclase of 

secondary growth having the same orientation. One such veinlet is characterized 

by zonal feldspar parallel to the walls, the fine zones being due to differently oriented 

stripes with a coarse, massive center of orthoclase and some albite. In this case 

the zonal part is muscovitized, the central part not, showing that the muscovitization succeeded the fracturing, while it preceded the general cementation. 

The quartz streaks and lenses occur chiefly in shaly limestone, altered in the 

lens zone to a bluish schist, and here containing small lenses (augen) of granitic 

material, but a few feet away from the lens zone the limestone is comparatively 

unaltered. The whole zone is capped by blue limestone, which is the bottom of a 

limestone series that is more massive than the limestone-shale series marked by the 

copious intrusion of alaskite and quartz and hence characteristic of the mineral 

district. 

Some of the alaskite has been crushed subsequent to the formation of both 

generations of crystals. In certain thin sections of such crushed rock some secondary crystallization was noted, which, apart from the common development of fine 

sericite in such cases, was the first observed instance of recrystallization following 

crushing. In such specimens the crushed orthoclase and microcline can be seen in 

process of irregular alteration to probable albite, although the alteration is not 

important. In another specimen the feldspar has been largely replaced by fine 

granular quartz, giving a structure suggesting quartzite and resembling the structure 

of the "bull" quartz of the Drinkwater mine. 
GOLD MINES .AND PROSPECTS OF MINERAL RIDUE. 65 

VEGA. 

The Vega property was worked about 1892, and a short time after its discovery 

produced about $3,000, the· ore being treated in a custom 2-stamp mill, which at 

that time was running at Tarantula Springs. Some of the ore taken here contained 

$100 to the ton: This ore contained galena and also altered pyrite. The rest of 

the quartz in t,he lens was not extracted. The lens is 4 feet wide at the center of 

the outcrop (fig. 13), but when followed in by a tunnel diminishes to nothing in 

about 50 feet (fig. 14). It also dwindles and disappears in both directions along the 

outcrop, so that it is a lens well defined in three directions. 

0 10 20 

FIG. 13.-Verticallongitudinal section of Vega ore lens at outcrop, taken at right angles to fig.14. 

The geology is identical with that in the Blair mines and others like them on 

Mineral Ridge. As shown in the sketch (fig. 14), the location is at the contact of 

the blue shaly limestone characteristic of the mineralized area with the conformably 

FIG. 14.-Vertical cross section at the Vega mine. A, alaskite; Q, quartz (ore body); S, dark shaly limestone; L, brown 

marbleized limestone or dolomite. 

overlying marble, which, so far as known, does not contain ore deposits. The foot 

wall of the lens is alaskite, the hanging wall schistose limestone overlain by alaskite. 

The last-named alaskite is quite uncrushed and is fresh. As is almost invariable 

in the alaskites of this district, it shows two distinct generations of crystallization. 

The first generation is represented by large grains of orthoclase, the second by a finer 

granular mosaic, consisting of quartz, microcline, and orthoclase, the first predominating; The crystals of this mosaic sink to fine dimensions. Some of the orthoclases of the rock are altered to fine muscovite, while some are clear. In one case 

13002-No. 55-06--5 
66 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

a crystal of the former is included in the latter, as if the alteration preceded total 

crystallization. 

The alaskite of the foot wall is somewhat crushed, but shows the same' composition and structure as that just described, and the crushing has not injured the 

freshness of the last crystallized feldspars. In this rock some of the quartz is very 

full of fine muscovite, similar to that in the older feldspars. In this case also the 

muscovite fibers are arranged along certain lines. 

Microscopic examination of the fine blue limestone of the hanging wall shows 

it to be an ordinary dense limestone with carbonaceous streaks and a sandy streak 

marked by fine quartz grains. 

A diorite dike, 4 feet thick, cuts across the alaskite. The microscope shows 

this to be entirely altered to quartz, chlorite, etc. Original ilmenite is abundant. 

RED MONSTER. 

This prospect is situated somewhat apart from others of its kind on Mineral 

Ridge, lying, as is shown on the map, farther northwest than these. The geology 

is of the Drinkwater type. Like most of the mines of the district, it is abandoned, and has been for some time. It is reported to have been worked a little in 

1899, and at that time one carload of ore was shipped to the Selby smelter. Nine 

tons were milled at the Silver Peak mill in 1892. The workings consist of an incline 

1:) feet deep and a drift 60 feet long at the bottom. The ore bodies are quartz 

lenses in schist, the main lens varying in thickness from several feet to a few inches. 

Some of the quartz has been stoped to a thickness of 2 feet, especially near the surface. 

Alaskite, sometimes muscovite bearing, is associated with the quartz at one point 

in the workings. A general section of the hillside shows different sheets of alaskite 

alternating with limestone schist. A specimen of coarse alaskite pegmatite, examined microscopically, shows two periods of crystallization, the first having resulted 

in coarse feldspar, largely orthoclase, with a little microcline and some striated 

feldspar. This feldspar incloses many small blades of muscovite, which are much 

coarser than the usual fibrous or sericitic variety, but have probably a similar origin. 

These feldspars have been strained and partly crushed and cemented with quartz 

and some feldspar. 

GREAT GULCH TYPE 

GREAT GULCH MINE. 

This is a gold-producing property of a different type from those previously 

described. It is located near the bottom of a deep gulch, southeast of the area of 

gold mines and prospects already described, and between these and the PocatelloVanderbilt group of silver mines. The mine is said to have produced $6,000 to 

$7,000. Ninety-eight tons of the ore, it is said, netted the owner $57 to $58 per ton. 

This ore was treated in Chiatovich's mill at Silver Peak, and the tailings were chlorinated. The property is opened by several cuts and tunnels, the longest being 

about 220 feet. These all follow streaks of ore. Below these, at the bottom of the 

gulch, a prospect tunnel was run in, under the direction of Tonopah parties, in 1903, 

but did not reach any ore. The tunnel, which is very tortuous, is about 240 feet 

long in all. · 
GOLD MINES .AND PROSPECTS OF MINERAL RIDGE. 67 

The property is situated on the east side of the gulch, near the bottom. The 

rocks forming the side of the gulch here consist of a thick series of stratified thinbedded limestones, considerably altered and schistose, .and dipping north at a modsw 

o.__ ___ _;_;:,o ____ ..::;"Z.ofeet 

FIG. 15.-Sketch section of portion of northwest side of canyon atJGreat Gulch mine, showing alaskitecutting across 

bedding of shaly limestone. 

erate angle. This series contains frequent interbedded lenses of alaskite. In places 

also the alaskite, contrary to its usual custom, cuts across the bedding of the limestone (fig. 15). The openings of the Great Gulch mine show that the general alignment of the ores is parallel with the strike and dip of the general formation. 

At the mine the general geology is similar (except for the ore) to that of all the 

other mines previously described. Lens~s of white vitreous quartz occur interbedded 

I 

0 s 10 ISteet 

~------~------~------~ 

FIG. 16.-Vertical section along raise in upper tunnel, Great Gulch mine, showing occurrence of ore. Q,, Quartz (lens); S, shaly 

limestone, somewhat altered; M, auriferous mispickel (ore). Dotted lines show outlines of raise. 

in the limestone schist. The quartz often becomes feldspathic and passes into 

siliceous alaskite, which also occurs in separate lenses. The distinctive feature of 

this mine, however-the one that distinguishes it from all the preceding-is the 
68 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

character and relative age of the mineralization. The ore is mispickel or arsenopyrite, and is subsequent in age to the quartz and ala~ite with which it is generally 

associated. The mispickel occurs in streaks of all thickness up to 1 or 2 feet locally, 

1ofeet 

FIG. 17.- Vertical section of incline from surface following on ore, Great Gulch 

mine. Q, Quartz in cross fracture; S, shaly limestone; M, mispickel (ore). 

Dotted lines show outlines of incline. 

but usually much less. The 

streaks are of very uncertain size, shrinking in places 

to small seams and again 

expanding into lenticular 

masses of solid ore. The 

largest masses of ore are 

noticeably associated with 

the alaskite and quartz 

lenses, especially with the 

latter, and occur occasionally as cross-cutting streaks, 

but usually as bands parallel to the walls of the lenses 

and to the attitude of the 

limestone schist (fig. 16). 

The hanging wall of a quartz lens is an especially favored location, and in this case 

the ore lies either in the fractured quartz, or above in the lirr.estone, where it generally 

FIG. 18.-Vertical section in short drift near end of upper tunnel, Great Gulch mine. A, Alaskite; Q, quartz; Q', quartz (feldspathic), much broken; S, shaly limestone, considerably altered to schist; M, mi3pickel (ore). Mispickel occurs along a 

fault zone on both sides of the crushed quartz, especially on the hanging-wall side. 

forms seams between the laminre of the sedimentary rock (fig. 17). The ore has 

originated partly by replacement, not only of the limestone schist, but also sometimes 

of alaskite. Cases were noted where an alaskite lens is locally almost completely 
DESCRIPTIVE GEOLOGY 01!' MINES .AND PROSPECTS. 69 

replaced by mispickel, except for residual portions here and there. Frequently the 

arsenopyrite streaks follow both the hanging wall and the foot wall of a quartz lens 

(fig. 18). The general situation is well expressed in the accompanying figures. 

It is evident that the preferential association of the arsenopyrite with the quartz 

and next with alaskite is due to the fact that these afforded better fractures when subjected to stress than the inclosing schist. The solutions which deposited the arsenopyrite followed fractures ere- N E: sw 

ated by stress subsequent to 

the consolidation of the 

quartz, and only in the rigid 

and brittle materials, such as 

the quartz, and to a less extent the . alaskite, were the 

openings produced by fracturing sufficient to allow vigorous 

circulation and ore deposition. 

It is therefore easy to understand why the ore streaks are 

nonpersistent, and become 

faint, split, and die out in the 

0 5 

FrG. 19.-Vertical section at opening of chief tunnel, Pocatello mine, showing 

quartz in schist. D, Greenstone (altered diorite); Q, quartz; S, blue schist 

(altered shaly limestone). 

schist. The preferential location of the ore at the hanging wall of the quartz lenses 

indicates rising solutions. These ascended through the fractured quartz till their 

progress was impeded by the relatively impervious overlying schist, and beneath this 

impervious contact the ore deposition took place. 

SILVER MINES .AND PROSPECTS OF MINERAL RIDGE. 

POCATELLO. 

At the Pocatello silver mine the ore follows a zone of rather small and nonpersistent quartz lenses which are similar in every way in appearance, age, association, 

and origin to the quartz bodies which form the ore in the typical gold mines of the 

SE 

Schist Greenstone Quartz 

Scale of feet 0 10 . 20 30 40 

~----~----~----~--~ 

FIG. 20.- Vertical sketch section of open cut on ore zone at Pocatello mine, showing faulting. 

NW 

district. The lenses lie in a blue schist, which represents a more or less altered shaly 

limestone (fig. 19). The lens zone is fiat, lying with the formation, but is undulating 

and somewhat faulted (fig. 20), and this fact, in connection with the variations in the 

topography, brings about very irregular outcrops. What is probably the same zone 

outcrops about 100 yards southeast of this point on top of the ridge overlooking Silver 

Peak. 
70 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

The ore is later than the quartz. It consists largely of a black metallic mmeral occupying cracks in the quartz-the "black metal" of the miners. This is rich 

in silver and yields a stain of copper carbonate. 

The alaskite is in lenses, which are associated with the quartz lenses in the typical 

way so often described for the gold mines. Locally this alaskite has a granitic phase. 

A thin section of this biotite-bearing alaskite, or biotite granite, proves to be 

uncrushed and nearly fresh, with a structure and texture like that of the ordinary 

alaskite. The biotite is a sparse essential and is extraordinarily full of rutile 

needles. Some of the orthoclase is altered to fme muscovite or sericite, while some is 

not. In one case a sericitized core of probable orthoclase is surrounded by clear 

orthoclase, as if there were two periods of crystallization. The microcline also, which 

is more abundant than the orthoclase, is absolutely fresh, and thus seems subsequent 

in origin to the sericitized feldspar. In several cases the microcline was observed to 

inclose small idiomorphic crystals of partly sericitized orthoclase. Included biotite 

crystals were also noted in a similar situation, as if the small orthoclase and biotite 

crystals had floated free in the fluid from which the microcline crystallized. The sericitized feldspars are sometimes microscopic_ally fractured, and in these fractures veinScale offeet 0 10 20 30 

FIG. 21.-Vertical sketch section along open cut on ore zone of Pocatello mine, showing diorite cutting and inclosing earlier 

schist and quartz. The ore is contained in !)racks in the qua rtz near the diorite contacts. Q, Quartz; D, greenstone 

(altered diorite); S, schist (altered sh aly limestone). 

lets of quartz and orthoclase are formed. The fresh orthoclase of the later period of 

crystallization sometimes incloses idiomorphic quartz grains. 

A specimen of the schist from near the vein proves to be intensely altered. The 

microscope shows it to be an aggregate of fine sericite pierced by subsequent veinlets 

and nests of fine intercrystallized granular quartz and calcite. Fresh grains of feldspar (chiefly microcline, sometimes orthoclase) occasionally occur. 

Southeast of the mairi vein outcrops on top of the ridge that overlooks Silver 

Peak village there is an interesting section showing the relation of the schistose, thinbedded limestone in which the quartz lenses occur to the overlying brown crystalline 

limestone or dolomite which does not contain ores. The marble overlies the thinbedded, shaly limestone series conformably, and there is a transition between the two 

which, although it occupies only a few yards, is gradual. Alternating layers of brown 

marble and dark thin-bedded schist occur for a few yards below the contact, the thickness of the layers of marble gradually increasing upward until the massive marble formation is reached. The phenomena are those of. a change of sedimentation, and 

the change indicated is that from a shaly thin-bedded, calcareous sediment to massive 

limestone. Alaskite seams are especially numerous toward the top of the schistose 

series, but do not extend into the brown marble. However, a number of small alaskite lenses and quartz lenses are found above the lowest strong band of marble which 
SILVER MINES AND PROSPECTS OF MINERAL RIDGE. 71 

is intercalated with the schistose bands. Evidently the shaly series has been selected 

for intrusion by alaskite and accompanying quartz because of its easy fissility, and 

for this reason this formation is ore-bearing, while the overlying massive limestone is 

barren. 

The ore zone is frequently cut by greenstone dikes, which are in general parallel 

with the zone, but are occasionally transverse. Thus the greenstone divides, underlies, or overlies, as the case may be, the quartz which constitutes the ore (fig. 21). 

Frequently the quartz near the greenstone intrusions was noted to be especially 

cracked, blackened, and mineralized. From one locality two general samples were 

taken from the same quartz mass; one of the blackened quartz within 2 inches of the 

greenstone contact, the other of the whiter quartz several inches away from it. The 

first assay yielded gold, 0.34 oz.; silver, 2.5 oz.; the second, gold, trace; silver, 0.2 oz. 

Some connection of the greenstone with the localization of the ore is thus indicated, and it is probable that the connection is that the intrusion of the greenstone has 

fractured the adjacent quartz so as to provide here channels for the circulations which 

accomplish the later, and in this case the main, mineralization. 

Under the microscope the greenstone proves to be an altered diorite of the usual 

type. The present constituents are secondary quartz, chlorite, calcite, etc., with 

much ilmenite and a little pyrite. 

VANDERBILT. 

As shown on the map, the Vanderbilt mine is a short distance southeast of the 

Pocatello and is probably on the same zone of lenses. The outcrops of the Vanderbilt 

extend down the east side of the ridge for about a quarter of a mile, and along this outcrop the ore zone has been developed and worked by open cuts and tunnels. 

The ore zone has a general strike of N. 60° E. and dips 20° SE., but varies considerably. Although the zone is persistent, as noted above, and is probably continuous 

with the Pocatello ore zone, it is doubtful whether any through connection could be 

traced between the different veins or leads in this zone. 

The general geology is like that of the Pocatello. Thin-bedded, bluish limestone, somewhat metamorphosed to schist, is here intruded by more or less lenticular 

sheets of alaskite (with granitic phases) and of quartz, which is directly transitional 

into the alaskite. In this quartz the ore occurs, but in such a way as to prove that it 

is of subsequent origin, like the ores of the Pocatello and the Great Gulch mines. The 

lo,cation of the ore is essentially determined by two conditions-first, the quartz lenses; 

second, the proximity of the greenstone or diorite sheets or dikes. These sheets are 

abundant and vary in thickness from a few inches to 3 or 4 feet. They generally lie 

parallel to the stratification, although they may leave it and crosscut the formation. 

By preference they follow the series of aligned quartz lenses which constitute a definite zone in the altered shaly limestone. The diorite overlies or underlies the lenses 

so as to form a hanging or foot wall, or both, or even splits the quartz and divides it 

(figs. 22 and 23). The quartz near the diorite is strongly fractured parallel to the contact, and in these fracture cracks the black silver-copper mineral which forms the ore 

has been deposited. Thus the rich ore is oftenest most closely associated with the 

diorite, and may occur along both the hanging and foot walls of a dike. Where such a 
72 ORE DEPOSI'tS OF SILVER PEAK QUADRANGLE, NEV .ADA. 

dike leaves the zone of quartz lenses, however, as it frequently does, the ore does not 

follow it, but continues within the lens zone along the contact of some other diorite 

sheet which has followed the zone more closely. The diorite sheets show a tendency 

to keep a straight course, so that where the quartz lens zone alters its position rather 

suddenly by folding or faulting the 

S Surface N diorite is apt to keep straight on, and 

0 

FIG. 22.- Sketch of outcrop, Vanderbilt ore zone, showing greenstone (altered diorite) cutting quartz. S, Limestone schist; Q, 

quartz (ore); D, greenstone. 

so leave the zone. 

A specimen of the altered limestone 

into which the alaskite and quartz is 

intruded proves on microscopical 

study to be a true limestone, containing, however, scattered isolated fresh 

grains of quartz, orthoclase, and 

oligoclase-albite, which have probably formed by replacement and are 

the result of metamorphism due to 

the siliceous intrusions. 

A thin section of a granitic phase 

of the alaskite contains muscovite and biotite in relatively small amount. Both 

muscovite and biotite are inclosed in microcline, and the muscovite is inclosed in 

orthoclase. An interesting feature of this rock is that the quartz grains are somew 

FIG. 23.-Sketch of vertical side of open cut, Vanderbilt mine, showing greenstone (altered diorite) surrounding a small quartz 

lens. S, Limestone schist; D, greenstone; Q, quartz (ore) ; A, alaskitc. 

times arranged in strings, showing a commencement of segregation which, if carried 

further, would form a small veinlet. The whole rock is perfectly fresh and uncrushed. 

A specimen of the quartz which constitutes the ore shows under the microscope 

the peculiar structure noted in the granitic alaskite just described and in almost 
SILVER MINES AND PROSPECTS OF MINERAL RIDGE. 7'3 

every specimen of alaskite :from Mineral Ridge that has peen studied microscopically. 

The rock is made up of large grains, interstices between which are filled with a cement 

of much smaller grains, of apparently a later generation. The only difference between 

this and the alaskites seems to be that here the grains are all quartz; otherwise the 

texture and structure are similar. 

BLACK WARRIOR. 

As shown on the map, this abandoned mine is situated in a formation that is 

different :from any of those previously described. It is located in the brown crystalline dolomite which overlies the shaly limestone series of Mineral Ridge. The 

outcrops of the Black Warrior ·veins extend west-northwest along the face of the 

foothills for 100 to 150 yards; they have been opened by considerable workings. 

The deposits consist of veins or bands of quartz and jasperoid or silicified 

marble, running parallel to the bedding planes of the dolomitic marble or occasionally 

N 

s 

0 100 feet L-~~~--~~--------~ 

so 

FIG. 24.- Vertical cross section sh owing relation of vein in ma in Black Wa rrior workings. D, Greenstone (altered diorite); 

Q, quartz (ore); L, brown cryst alline dolomite. 

crosscutting them. The veins are irregular in form, without straight walls, and 

are evidently chiefly due to the replacement of the marble. The jasperoid is a densetextured rock and is white, like the marble whence it is derived. The microscope 

shows various stages of silicification between crystaWne dolomite and entirely 

silicified rock, the change being accomplished by the growth of interlocking idiomorphic quartz crystals, which form a typical retiform structure or network like 

that characteristic of rocks of this origin. a The quartz containing the ore is coarser, 

but has in general the same structure and may be termed a jasperoidal quartz or a 

semijasperoid. 'rhe veins are believed to be the result of r<?placement' of dolomite 

by waters obtaining access along :fracture planes and spreading out also along convenient stratification planes. 

The main vein, which is considerably developed by a tunnel, is, like most of 

the rest, a bedded vein with an average thickness of 3 or 4 feet. Other veins of 

much the same character are exposed at different places. These veins are only 

locally productive of high-grade ore. The good ore is characterized by the presence 

a Mon. U.S. Geol. Survey, vol. 31, p. 219. 
74 ORE DEPOSITS ·oF SILVER PEAK QUADRANGLE, NEVADA. 

of a black metallic mineral in disseminated streaks in the quartz. This mineral 

is plainly primary and contemporaneous with the quartz, so that the ore deposit 

belongs in a somewhat different class from the Vanderbilt and Pocatello silver 

mines. The values are irregularly disseminated in the qnartz vein, and often are 

especially abundant near the hanging and foot walls. The black ore mineral is 

evidently the same as in the case of the Pocatello and Vanderbilt, and is rich in 

both silver and copper. It yields azurite and malachite on oxidation. Disseminated galena also is associated with this "black metal." 

Greenstone dikes or sheets occur in the dolomite, chiefly parallel to the bedding. 

In the main tunnel, where most of the ore was found, a greenstone sheet constitutes 

the foot wall of the chief vein. The greenstone is a much-altered rock, the microscope showing it to consist entirely of secondary materials like quartz, carbonates, 

etc. It is of the same character as the greenstone or altered diorite dikes which 

have been described in connection with nearly every other ore deposit of Mineral 

Ridge. The relative age of the diorite and of the ore deposit is, in this case, not 

clear from the observed phenomena. There is no ore in the greenstone, however, 

(fig. 24). 

FOLEY'S AND PALMETTO COMPANY'S 1PROSPECTS. 

These two prospects lie 200 or 300 yards apart, on the extension of the Black 

vV arrior zone. The country rock is brown Cambrian dolomite. The veins consist 

Surface 

5 

FIG. 25.- Vertical sketch section showing relations of veins at 

Foley's prospect. Q, Qnartz; D, greenstone (altered diorite); 

L, crystalline dolomite. 

of white quartz and white or brownish 

jasperoid, forming regular or irregular 

bodies, which in several observed cases 

cut across the faint stratification of the 

dolomite. None of these veins are 

traceable very far, but die away along 

their strike into silicified dolomite. 

They are evidently largely the result 

of displacement. 

Some of the veins are accompanied 

by greenstone or altered diorite, which 

may occur both on the foot or hanging 

wall or both. It is somewhat uncertain here, as in the Black Warrior, 

whether the greenstone or the quartz 

is the older. The accompanying sketch 

section (fig. 25) shows an exposure 

which gives the impression that the 

quartz is the later and has followed and cut a greenstone dike. 

The pre is of the same nature as that at the Black Warrior, the values consisting in disseminated sulphides, especially the black metallic mineral, which yields 

copper on oxidation. 
DESCRIPTIVE GEOLOGY OF MINES AND PROSPECTS. 75 

MINES AND PROSPECTS IN THE VICINITY OF LONE MOUNTAIN 

ESPERANZA. 

The Esperanza is situated on the extreme edge of the area shown on the map. 

The vein lies in rather thin bedded, often shaly, green and blue limestones, weathering brown. The strata are highly folded. In this formation are small, crosscutting, irregular veins, and there are also quartz seams following the stratification. 

These interstrati:fi.ed seams are apt to be of irregular size, not traceable for any 

long distance, and to be represented rather by irregular quartz veinlets within a 

given bed or zone than by a regular, well-defined vein. 

At the time of the writer's visit the main workings on the Esperanza consisted 

of a short incline. At the surface the vein showed somewhat over a foot of quartz 

and was fairly well defined. Along the strike, 

however, the vein could not be traced far in the 

same strength. In the quartz the values consist 

of copper, lead, silver, and gold, especially silver. 

The ore-bearing minerals consist of the black 

complex mineral mentioned in previous descriptions (containing all the four metals mentioned) 

and galena, with pseudomorphs of limonite after 

pyrite. There is some calcite in parts of the 

gangue. Secondary chrysocolla was noticed. 

PAYMASTER. 

The Paymaster is a half mile east of the 

Esperanza and is outside of the area shown on the 

map (Pl. XXI, A). It is in the same green shaly 

limestone as the mine previously described. Its 

rocks are of Cambrian age; the writer collected 

lower Cambrian trilobites between the Paymaster 

mine and the Paymaster camp. Some ore has been 

shipped from both this mine and the Esperanza. 

The character of the ore is very much alike in the 

two mines. The upper part of the Paymaster ore 

was fully oxidized and iron stained, and contained 

some native silver of secondary origin. The Paymaster vein where opened up near the surface 

shows 12 to 14 inches of white, rusty, and shattered quartz, with a regular and well-defined wall. 

About 100 feet southwest of the shaft what is 

probably the same vein outcrops, only a few 

inches thick. The thickness also varies vertically, 

FIG. 26.-Vertical cross section of Paymaster 

vein at shaft. Dotted lines show sh aft; L, 

shaly limestone (country rock); Z, crushed 

and decomposed zone; Q, quartz (ore) . 

as is shown in the inclined shaft by which the vein has been opened. 

The character of the vein zone is more persistent. This is essentially a crushed 

or fractured zone in limestone, but the amount of quartz which has formed in it 

is variable and in places the quartz may even disappear (:fig. 26). 
, 

76 ORE DEPOSITS OF SILVER PEAK QUADRANGLE NEVAD.A 

UTOPIA. 

The Utopia is also located outside of the area included on the map, being about 

a mile and a half north of the Paymaster camp. The country rock is light-colored 

dolomite (often white), thin bedded, and brown weathering. The mineralized zone, 

as developed at the time of the writer's visit, was about 500 or 600 yards long and 100 

to 200 feet wide and has a general north-south course. In this zone are small, weak, 

NW 

0 10 

FIG. 27.- Vertical cross section of typical interbedded vein, 

Utopia prospects. D , Shaly altered dolomite; Z, crushed and 

decomposed zone; Q, , quartz (ore). 

and nonpersistent quartz veins . . Usually these veins are less than a foot 

thick and none of them are traceable 

far. · The general strike of the veins 

is parallel to the stratification of the 

Cambrian beds in which they lie, and 

the general dip is easterly with the dip 

of the strata. Thus most of the veins 

are parallel to the stratification, but 

many cut across the dip and some 

across the strike. The quartz which 

constitutes the ore is to be considered 

as an accompaniment of certain zones 

of crushed rock which have pretty 

well defined courses and walls. In 

these zones the quartz may ,be scattered or may follow the hanging or the 

foot wall, but is not usually persistent 

(figs. 27, 28). 

These prospects belong in the same 

geological group as the Paymaster 

and Esperanza mines previously described. All are small and nonper-

·sistent veins in Cambrian limestones 

and slates, generally, but not always, 

parallel with the stratification. All 

followed similar crushed zones, evidently due to disturbances in the 

limestones, which afforded channels for the circulating mineralizing solutions; but 

the supplies of such solutions were certainly very scanty. In all the character of the 

ore is the same, consisting of a quartz gangue carrying small amounts of nch silverbearing sulphides with some galena, pyrite, and secondary minerals, such as 

chrysocolla, probable chloro-bromides of silver, limonite, etc. 

At the Utopia the dolomite which forms the walls of the veins becomes characteristically altered and spotted. A specimen of this examined microscopically is 

found to consist mainly of a fine fibrous mineral, probably sericite, with some quartz. 
MINES .AND PROSPECTS NEAR LONE MOUNTAIN. 77 

ENTERPRISE GROUP OF PROSPECTS. 

In the northeast corner of the area shown on the map, south of Lone Mountain 

and also farther east, off the area mapped, there are a number of prospects which 

have many characters in common. The name is given from the prospects of the 

Enterprise Company, which are typical. 

The Enterprise prospects are situated along a metamorphosed zone in calcareous sediments. This zone, which trends N. 36° E., was followed by the writer 

for over 1.500 feet and is said to extend for over a mile. The dip is nearly vertical, in 

general steeply west, with the inclosing formations. A typical cross section of the 

metamorphosed zone is shown in fig. 29. The zone varies in width, averaging about 

60 feet and has sometimes rather indefinite boundaries. It is marked by the 

coarsely crystalline minerals which are characteristic of metamorphosed impure 

limestones, principally epidote and garnet. The garnet is usually green in thin section and is optically anomalous, 

being decidedly doubly refracting, especially the coarse crystals. Other minerals w hi c h 

occur more or less abundantly 

are magnetite, specular iron, 

quartz, and calcite. Zoisite, 

chlorite, actinolite, hornblende, 

and probable orthoclase, albite, 

and wollastonite were also found 

in the thin sections. In one 

section large idiomorphic crystals of an altered mineral, probably originally andalusite, now 

entirely decomposed to sericite, 

quartz, etc., were seen. In 

places along the zone any of the 

commoner minerals may become 

FIG. 28.- Sketch of vein in open cut on Utopia property. D , Altered white 

dolomite; Z, crushed and decomposed zone (probably sheer or fault 

zone) ; Q,, quartz (ore). 

very abundant, so as to form the greater part of certain bands. Thus there are 

bands of magnetite, epidote, and garnet, respectively, and in one place quartz is 

abundant to the exclusion of other minerals, forming a "vein" which, however, 

gradually changes to epidotic rock. Besides the metallic' minerals above mentioned pyrite, chalcopyrite, and galena occur in limited amounts, and this ore 

contains a certain amount of gold and silver. Some of it has been reported to contain tin, but tests of two samples made in the laboratory of the U. S. Geological 

Survey do not· show any. Some silver ore from a point farther north on this 

same zone is said to have been hauled to Columbus and milled over twenty-five 

years ago. 

Bands of white crystalline marble alternate with the bands composed of the other 

metamorphic minerals just mentioned and also occur above and behw these bands. 

West of the zone, stretching between it and the contact of the granite, which lies 

at its nearest point about two-fifths of a mile distant, are thin~bedded slates, considerably metamorphosed and resembling in a general way the calcareous slate series 
78 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

of Mineral Ridge. A specimen of these slates examined microscopically proves to be 

very fine grained. It consists of lighter portions and slightly darker bunches, which 

"' 

0 

0 

.... 

0 · 

.. , give the schist and hand specimen a spotted appearance. ~t: :E ~ The first-named areas are chiefly sericite, while the spots 

! ~ are more complex, consisting of quartz, sericite, some 

~ ~ magnetite, and occasional glaucophane. 

;;. :a On the eastern side of the coarsely crystalline meta-

_..::., 

~ ~ morphosed zone which contains the ores the rock is - Q) 

~:;;; typically dark-blue crystalline limestone, often metamor- ~- '" .. phosed along certain interstratified bands or along irreg-

"§> ~ ular, vein-like, cross-cutting seams to white marble. In 

""-" 

~ ~ some of the marble near the coarsely metamorphosed zone 

~~ a little tremolite was found by microscopic study. 

~ s The situation of the coarse metamorphosed zone which 

:a 2l contains the ores and is characterized by coarsely crystalline ·~ ·~ ~ 0 epidote, garnet, etc., between the metamorphosed slates 

::-:. and the metamorphosed pure limestones indicates that 1t 

·Z .& represents a sedimentary bed of a composition differing A:;; "" "' from and probably transitional between the rocks on either db 

.§ s side-that is to say, probably an impure calcareous sedi-

~ .g ment. The continuation of metamorphism to the granite 

~- :g contact indicates that the alteration has been due to the ...,..,. "" - ~ ~~ 

~" ~ 8 <> -o ~ ~ ;o~ 

"" 0 sa 

"'Q) 

.~ -g -:a"" Ol-o 

... '" aa~ ·~::: 

0 "' .d Q) 

"' ::l 

gc.: 

o"' "'·-.'< 

~ 8 

.~ >: 

e.~ 

~~~ ~a:>.S ~...,., 

0 0 "' 

§ ~~ :;::; Q;) <l) 

~~;§ 

~g:§ 

0 " "' ... -.... O"'" 

I '"' " o)Jl§ 

~e-i:O 0 

~ 

granitic intrusion. Such metamorphism, affecting a series . 

of sediments of varied composition, such as we have here, 

would naturally produce these varied results, and the 

original composition of a sedimentary bed transitional 

between a limestone and argillaceous sediment might be 

sufficient to account for the crystallization of a distinct 

metamorphic zone marked by its own peculiar minerals, 

such as occurs here in the zone characterized by epidote and · 

garnet. Within this zone bands of epidotic rock, of pure 

marble, and of dense metamorphic rock like the metamorphic schist which constitutes the east wall are sharply 

divided from one another, frequently by absolutely clean 

and straight lines, as if the different bands represent layers 

originally different (fig. 30). On the other hand, irregular 

veins of marble cut across the dark-blue limestone which 

lies east of the zone under discussion, showing that the 

metamorphism of the limestone to marble in such cases 

was accomplished by solutions circulating along crosscutting fractures (fig. 31). Moreover, within the garnetepidote zone veins of coarsely crystalline epidote cut and 

include bunches of denser rock, pointing to the same action 

as in the case of the marble veins. The frequency of these 

phenomena indicate that this zone . has been also a zone of fracturing. 

An intercalated intrusive sheet of diorite about 10 feet thick runs along this ore-
MINES AND PROSPEC'TS NEAR LONE MOUNTAIN. 79 

bearing metamorphosed zone at one point. It is composed chiefly of feldspar and 

hornblende and is considerably altered to epidote, cloudy carbonates, and quartz. 

Throughout most of the zone, however, no diorite was encountered. 

The general conclusion reached is that at the time of the intrusion of the near-by 

granitic mass fractures sufficient to 

permit an unusual facility of water 

circulation were formed along a zone of ...... 

sediments transitional between limestones on the one side and slates on 

the other. Solutions emanating from 

the granite penetrated the strata and 

metamorphosed them for a considerable distance from the contact. 

Along the fracture zone in impure 

limestone the circulation was especially vigorous, producing a coarser 

crystallization. Many of the elements 

in the metamorphic minerals produced in this zone were probably derived from the original sediment, 

helping to make the garnet, epidote, 

0 

FIG. 30.-Vertical cross section of outcrop of a portion of Enterprise ore zone at one point, showing origin of different bands by 

alteration of chemically different strata. I, Pure, coarse, 'vhite 

dolomite marble; 2, green rock containing much epidote; 3, 

probably metamorphosed calcareous slate (fine-grained mat of 

quartz, actinolitic amphibole, carbonates, etc.). 

etc. On the other hand, various elements were probably introduced into the zone 

from the granitic solutions-as, for example, the lead, copper, silver, gold, much of 

the iron, and many other elements in part or in whole. 

FIG. 31.-Sketch of outcrop near Enterprise ore zone, 

showing derivation of dolomite marble (1) through 

solutions circulating along a cross-cutting fracture in 

blue, sometimes thin-bedded, limestone (2). 

The Lone Mountain Syndicate is a prospect 

having geological conditions similar to those 

mentioned above but is not on the same 

zone. Its location, as shown on the map, 

is over 2 miles northwest of the locality just 

described. Between the two localities the 

rocks consist of fine dense quartzites, often 

containing some epidote, interbedded with 

crystalline schists which represent altered 

slates and with some beds of white marble. 

Bands of epidotic rock also occur. These 

are distinct from the other rocks, but often 

associated with marble bands, suggesting 

again that the original composition of these 

beds was largely responsible for the formation of epidote by recrystallization during 

metamorphism. Diorite dikes occur rather 

sparingly in this series. One which was 

examined microscopically is different from all the other diorites previously described, 

in that both the hornblende and the feldspar are comparatively fresh. 

In the Lone ~ountain Syndicate property a short incline was seen which goes 
MINES .A.ND PROSPEO'rS NE.A.R LONE MOUNTAIN. 79 

bearing metamorphosed zone at one point. It is composed chiefly of feldspar and 

hornblende and is considerably altered to epidote, cloudy carbonates, and quartz. 

Throughout most of the zone, however, no diorite was encountered. 

The general conclusion reached is that at the time of the intrusion of the near-by 

granitic mass fractures sufficient to 

· permit an unusual facility of water 

circulation were formed along a zone of 

sediments transitional between limestones on the one side and slates on 

the other. Solutions emanating from 

the granite penetrated the strata and 

metamorphosed them for a considerable distance from the contact. 

Along the fracture zone in impure 

limestone the circulation was especially vigorous, producing a coarser 

crystallization. Many of the elements 

in the metamorphic minerals produced in this zone were probably derived from the original sediment, 

helping to make the garnet, epidote, 

s feet 

FIG. 30.-Vertical cross section of outcrop of a portion of Enterprise ore zone at one point, showing origin of different bands by 

alteration of chemically different strat a. 1, Pure, coarse, white 

dolomite marble; 2, green rock containing much epidote; 3, 

probably metamorphosed calcareous slate (fine-grained mat of 

quartz, actinolitic amphibole, carbonates, etc.). 

etc. On the other hand, various elements were probably introduced into the zone 

from the granitic solutions-as, for example, the lead, copper, silver, gold, much of 

the iron, and many other elements in part or in whole. 

"FIG. 31.-Sketch of outcrop near Enterprise ore zone, 

showing derivation of dolomite marble (1) through 

solutions circulating along a cross-cutting fracture in 

blue, sometimes t\J,in-bedded, limestone (2). 

The Lone Mountain Syndicate is a prospect 

having geological conditions similar to those 

mentioned above but is not on the same 

zone. Its location, as shown on the map, 

is over 2 miles northwest of the locality just 

described. Between the two localities the 

rocks consist of fine dense quartzites, often 

containing some epidote, interbedded with 

crystalline schists which represent altered 

slates and with some beds of white marble. 

Bands of epidotic rock also occur. These 

are distinct from the other rocks, but often 

associated with marble bands, suggesting 

again that the original composition of these 

beds was largely responsible for the formation of epidote by recrystallization during 

metamorphism. Diorite dikes occur rather 

sparingly in this series. One which was 

examined microscopically is different from all the other diorites previously described, 

in that both the hornblende and the feldspar are comparatively fresh. 

In the Lone Mountain Syndicate property a short incline was seen which goes 
MINES AND PROSpECTS NEAR LONE MOUNTAIN. 81 

consist of a number of prospect shafts and inclines. Some of these are in pegmatite, which contains areas of segregated quartz. Others ;are in alaskite, generally 

fine grained and siliceous. These rocks are intrusive into limestone, which has been 

changed to marble and into beds of silvery mica schist-metamorphosed slate. The 

alaskite when seen in thin section resembles certain phases of the alaskite from near 

the Drinkwater mine on Mineral Ridge. It consists, essentially, of quartz and feldspar, the latter with a strong idiomorphic tendency, the former a later crystallization. 

The feldspar is mostly .orthoclase and some oligoclase. There are occasional small 

primary pink garnets and some primary muscovite, usually in small grains. In 

places this alaskite has been so altered that the feldspar is entirely changed to 

sericite. This alteration is associated with fine-grained cellular quartz, which constitutes the mineral exploited in these prospects. Examined microscopically, the 

quartz is a moderately fine-grained idiomorphic aggregate containing some pyrite. 

It is reported that this ore was of very low grade, so low as not to be available for 

mining. 

Several hundred feet east of these prospects in the alaskite and associated rocks 

there is a lens of quartz somewhat over 100 feet in length and 25 feet in maximum 

thickness, conforming to the stratification of the limestone in which it lies. This 

quartz wedges out and disappears in both directions along the strike. In its neighborhood is a smaller lens of the same kind, about 25 feet long. The quartz sometimes contains galena and is reported to be a low-grade gold ore. 

About 350 feet west of the quartz vein mentioned above is the locality whence 

the rich ore which created the excitement was taken. The country rock here is 

gently dipping limestone which has been altered to a fine-grained marble and in 

places more or less silicified, especially along certain zones. In this limestone there 

are small bunches of bluish quartz which show a faint copper stain. Calcite is also 

present. A thin section of the ore shows it to have the typical retiform structure of 

jasperoid. It has been formed by replacement of the original limestone by silica. 

This ore contains a black sulphide showing red, yellow, and green alteration products. 

It is very likely that this is the "black metal" which contains copper and silver in 

considerable amounts and is one ot the characteristic ore minerals of this whole district. Under the microscope free gold was observed, both intergrown w1th the black 

mineral and separate from it. This gold is inclosed in the quartz and is apparently 

original. 

ALPINE. 

The Alpine mine is located almost due north of W eepah, over 1 mile beyond the 

northern edge of the area included within the map. l1r was, however, visited by the 

writer and is of f:lOme importance, being the only mine among those described from 

the Lone Mountain region that has produced any considerable amount of ore. This 

mine shipped $209,000 worth of ore and paid dividends amounting to $70,000 on the 

results of its first year's work. 

The mine is situated in a district which lies near the intrusive contact of the 

Lone Mountain granitic mass with the Paleozoic limestones and interbedded slates. 

Near the granite a broad belt of the intruded limestone has been altered to white 

dolomite marble, while the slates are altered to crystalline schists. This belt is over 

13002--~o. 55--06----6 

/ 
82 ORE DEPOSITS OF ~HLVER PEAK QUADRANGLE, NEVADA. 

half a mile wide at the point examined. The strata are folded and faulted and in 

general dip away from the Lone Mountain granitic mass. The prevailing strike is 

northerly. The dip is westerly at a rather low angle. At the Alpine mine the prevailing strike is N. 70° W., and the dip is gently south, though the strata are rolling. 

A short distance farther north, at the Alpine Eagle prospect, the strata strike N. 30° 

W. and dip 18° SW. 

A specimen of a slightly impure bed in the limestone examined microscopically 

showed biotite, a little quartz, epidote, and serpentine, all developed as the result of 

metamorphism. 

A thin section of one specimen of the Lone Mountain granite shows it to correspond with the granitic phase of the Mineral Ridge alaskite. It consists mainly of 

feldspar and quartz and very subordinate biotite. Sphene, magnetite, and zircon 

also occur. The structure of the quartz and feldspar, broadly speaking, is allotriomorphic, but certain turbid portions of the feldspar which show the form of idiomorphic crystals are surrounded by clearer feldspar, the whole being intergrown with 

quartz. The idiomorphic cores and the clear later growths of feldspar are usually 

similarly oriented. The cores contain small blades of included original muscovite, 

FIG. 32.-Skctch of hillside outcrop of ore body following bedding plane of white dolomite- vertical section, Nevada Alpine 

mine. 

while the clearer feldspar does not. The feldspar is mostly orthoclase, both in the 

case of the earlier and the later crystallizations. Microcline is frequent, but is always 

fresh and belongs to the later period of crystallization, being contemporaneous with 

the quartz. This structure is interpreted to mean that after the usual first crystallization of magnetite, sphene, biotite, zircon, etc., idiomorphic feldspar crystals, now 

occupying about one-fifth of the section, separated out and floated free and 

detached in the magma. Subsequently these were corroded and partly altered to 

fine muscovite, for since the cores and the clear margins of the feldspar are both usually orthoclase, the theory of differential weathering or other alteration is not admissible. The phenomena indicate that the spaces between these original idiomorphic 

feldspar crystals were subsequently filled by crystallization of fresh orthoclase, 

which, joined on to the older feldspar, produces the present allotriomorphic grains. 

Subsequent, in general, to this later orthoclase some microcline and quartz crystallized out. 

In the metamorphosed belt of sediments near the contact of this granitic intrusion there are numerous seams of ore lying conformable to the strata and, according 

to prospectors, extending up as far as the granite, but not into it. The ores consist in 
MINES AND PROSPECTS NEAR LONE MOUNTAIN. 83 

part of small quartz seams containing galena. These contain silver, but are of low 

grade and are not mined. However, they lead to bodies of mixed galena and sandy 

lead carbonates, which often show copper and iron staining, due to oxidation. These 

ore bodies are the result of the replacement of the dolomite. They widen to irregular 

pockets or rough lenses and occur separately or strung together along bedding planes 

in the dolomite. Their general shape and size is best seen by diagrams (figs. 32 and 

33). Where examined in the vicinity of the Alpine mine, they are confined to a 

certain zone in the bedding-that is, the bedding planes which the ore bodies follow 

are comparatively close together. Thus the three chief ore bodies of the Alpine 

mine outcrop on the same zone, and farther north the prospects of the Alpine Eagle 

are at about the same stratigraphic position. Above and below this horizon, however, 

are lesser lenses of ore, following other stratification planes. These different ore 

horizons are called "floors" by the miners. In some cases the ore extends to a slight 

extent away from an interbedded lens, along perpendicular fracture planes at right 

angles to the bedding, but this 

is relatively unusual and unimportant. The ore bodies are of 

limited size and are separated 

from one another by much longer 

stretches of barren rock. The 

prospects which have been found 

outside of the horizon upon 

which the Alpine mine is situated have not yielded, any considerable amount of pay ore. 

There is very little quartz in the 

rich ore, but along the edges of 

the pockets galena-bearing 

quartz comes in, similar in nature to the low-grade quartz 

seams noted above. 

FIG.33.-Sketch (vertical section) of outerop of ore body (chieflycerussite) 

in dolomite n1arble, Nevada Alpine rnine, Lone Mountain district. 

In and near the ore bodies the dolomite is characteristically altered to talc, 

evidently by siliceous solutions acting upon the dolomite. This talc is sometimes 

stained green by copper. This characteristic a~teration occurs both near the lowgrade quartz veins and the richer replacement deposits, indicating a common origin 

for both. 

In the ore of the replacement deposits the lead carbonat~ is several times richer 

in silver than the galena. The shipping ore at the time of the writer's visit was said 

to carry 100 ounces of silver and up to 50 per cent of lead. The superior richness of 

the carbonate is probably due to an enrichment of the original values during alteration in the weathered zone. ·The galena found in the quartz on the edges of the 

richer ore is not altered to carbonate, which is probably due to the fact that the 

inclosing quartz has protected it. 

Diorite sheets, and to a less extent cross-cutting dikes, are abundant in the 

marble and occasionally in the granite, but do not seem to be in any way associated 

with the ore and are propably of later origin. 
, 

84 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

PROSPECTS IN THE SOUTHERN HALF OF THE QUADRANGLE. 

DYER DISTRICT. 

The Dyer district is located a mile east of Dyer's ranch, in Fish Lake Valley. 

It lies a short distance beyond the western edge of the area shown on the map just 

west and northwest of the small area of granitic rocks south of the junction of the 

southeastern edge of Fish Lake Valley with the foothills of the range, at the point 

where this junction is cut by the western boundary of the area mapped. In this 

district, within a space of about 1 square mile, are a number of prospects, which, it 

is reported, were worked upon in 1863 and 1864, though no ore was shipped. Later on 

these and other prospects were worked, especially between 1884 and 1887. From 

0 20. '1-0 so feet 

FIG. 34.- Vertical section of chief prospect in D yer district. 1, T hin-bedded sla t y limesto ne; 2, c rushed a nd decomposed 

zone a long bedding, growing less in depth; 3, quartz (ore); short dash lines show incline a nd cross cut. 

one of the prospects a few tons of ore are said to have been shipped to the Monte 

Diablo mill in Soda ville in 1887, and from another prospect some ore is said to have 

been shipped to Columbus. At this period a mining camp sprung up here, which, 

however, was short lived. Since the discovery of Tonopah these claims have been 

relocated, but when visited by the writer in the summer of 1903 nothing had been 

done, in most cases not even assessment work. 

The prospects are on zones of crushed and decomposed rock, almost always 

parallel to the stratification of the thin-bedded, spiceous, shaly limestones in which 

they occur. Separate crushed layers of this sort sometimes unite by thickening up. 

Within these crushed zones there are discontinuous, irregular, and small stringers of 
PROSPECTS IN THE SOUTHERN HALF. 85 

quartz, carrying the black silver-copper sulphide ("black metal") that is characteristic of the silver ores of the quadrangle. When oxidi~ed, these ores are crumbling 

and show iron and copper stains, and a yellow-green stain that is probably silver 

chloride. Both vertically and horizontally the ore is apt to peter out rapidly and 

disappear, giving place to the soft gouge of the crushed zone, exactly as in the case 

of the group of veins of which the Paymaster, Esperanza, and Utopia are examples. 

In fact the group of veins just mentioned is identical in every geologic feature with 

those in the Dyer district, except that those last named are weaker. The crushed 

zone also, though more persistent than the argentiferous quartz which it contains, 

frequently becomes weak in a short distance and passes into fractured limestone. 

Fig. 34 gives a cross section of the most important of these prospects visited. 

Throughout the district examined the limestone is full of bunches of quartz similar 

to those described, hut discontinuous as to horizontal and vertical extent, and 

changing very rapidly to absolutely nothing. They are nearly all bedding-plane 

deposits. 

The values in these ores are silver, the picked ore in one or two of the most 

important prospects being claimed to assay from 74 to 120 ounces silver. A few 

hundred yards south of one of the principal prospects mentioned above there is an 

outcrop of specular iron ore, opened up by an open cut and a little incline. This ore 

is in sandy siliceous limestone and seems to be essentially a bedding-plane deposit, 

from which tongues cross cut the formation irregularly. The ore deposit seems to 

have no definite shape, and the ore does not seem to be in any considerable quantity. 

GOOD HOPE PROSPECT. 

This was not visited by the writer. The following description is by Mr. H. W. 

Turner: 

The aba.ndoned Good Hope mine is situated about 7 miles south of Piper Peak. Tlw country rock is slate, 

presumed to be of Ordovician age. The beds strike northwest-southeast and dip NE. 40°. In these slates is 

a layer of a light-colort>d quartzite, and along the contact of the quartzite with the nnderlying slates there is 

more or less quartz containing galena and showing copper stains. There are several cnts and tunnels and a 

stone cabin in the gnkh to the south. The ore is said to have been worked for silver and reduced in a little 

furnroce on Furnace Creek in the foothills of the Inyo :Mountains. 

WINDYPAH, OR FESLER, DISTRICT. 

GENERAL FEATURES. 

In this district there are a number of prospects, but at the time of the writer's 

visit, in the summer of 1903, there were no developed mines. The district is located 

in the southwestern part of the area included in the map. Geologically the prospects 

are centered around the intrusive granitic body which is found in that region, the 

deposits occurring either in the granite or in the contiguous Paleozoic limestones and 

slates into which the granite is intrusive. The district was discovered in the winter 

of 1903 by J. E. Fesler. 

Some of the granite of the district is similar in appearance to the granite of the 

Lone Mountain district in the northeastern part of the quadrangle. Other phases 

are coarsely porphyritic, with phenocrysts of feldspar, some as much as 3 inches in 

' 
86 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

length. In this granite and in the limestone near the granite eontact are frequent 

aplitie dikes, usually of alaskite, often eontainirig nests of segregated quartz. These 

dikes are regarded as a phase of the granitie intrusion, later in eonsolidation than 

the main mass of the granite, and are believed to have been separated from the 

granitie magma by the crystallization of the less silieeous typical granite. In the 

portion of the granite exposed at the present surface the aplitic dikes of alaskite 

usually cut the granite and show the ordinary phenomena of intrusion. In this case 

they have eyidently not segregated directly from the granite with which they are in 

eontact, but were probably derived from a lower horizon, whence they have ascended 

to cut the overlying cooler and earlier· consolidated granite. 

VEINS. 

The veins found in this district are divisible into four distinct classes: 

1. Segregations in alaskite. These consist of lenses and bunches of quartz of 

very limited size, directly segregated out of and contemporaneous with surrounding 

alaskite. The lenses have not been proved in any case to be of large size or abundant or to have any regular connection between themselves. The quartz, as well as 

some of the alaskite, contains original pyrite and sometimes shows good values in 

gold. 

2. Quartz veins following along shear zones in granite. These veins are locally 

xenogenous, having penetrated the granite along crushed or shear zones. The supplies of mineralizing solutions have evidently not been copious, nor were the channels 

strong. This is shown by the fact that the walls are ill defined ·and the amount of 

quartz variable. The mineralogical character is like that of the veins of the first 

class, the quartz carrying scattered auriferous pyrite. Locally good assays in gold 

are obtained, but as all the workings are near the surface the values in this and other 

classes have probably been concentrated during oxidation. The veins, however, are 

in general better defined than those of the first class and are occasionally traceable 

some little distance. Often, however, they have the form of numerous stringers in 

the granite whose extension is uncertain. These ores also probably have a genetic 

connection with the granitic intrusion. It is believed that highly siliceous residual 

material segregated from the consolidating granitic intrusion at a somewhat lower 

horizon has ascended and penetrated and mineralized the already consolidated 

granite along available channels caused by fracture. 

3. Veins in the limestones and slates at or near the contact of granite. These 

belong mineralogically in the class of noble silver-quartz veins or quartz veins containing highly argentiferous minerals with relatively small amounts of baser minerals. They are characterized by rich black auriferous sulphide of silver and copperthe "black metal" of Nevada miners. The nature of this mineral, which has previously been frequently referred to, will be discussed further on (p. 91). Veins of 

this sort are very persistent, following at or near the granitic contact sometimes for 

miles, or extending in a· direction away from the contact almost or quite as far. A 

favorite location for these veins is along the contact of alaskite dikes with limestone. 

These veins, though persistent in length and probably in depth, do not as a rule have 

well-defined walls and are to be regarded as replacements of the wall rock along 

fracture zones. Frequently an alaskite dike has such a vein on both sides, though 
PROSPECTS IN THE SOUTHERN HALF. 87 

more or less intermittent. The ore oxidizes to silver chloride, copper carbonate, and 

free gold. 

4. Lastly comes a type of veins intermediate between the second and third 

described above. These are veins in the granite carrying, so far as studied, a.lmost 

entirely gold values, but having a mineralogica.l composition intermediate .between 

classes 2 and 3. Besides pyrit~, they ~ontain more or less black metal, as well as 

chalcopyrite and galena, and alteration may produce characteristic oxides and carbonates, such as malachite, cerussite, probable black oxide of copper, etc. 

These four classes of veins are all believed to have been due to different forms of 

the same mineralizing agent, namely, the siliceous fluid which was segregated out of 

the granitic magma by the crystallization of the earlier granitic materials that form 

the true igneous rocks. 

The first class has segregated directly from the alaskite, which is a phase of the 

granite; the ore has the same relation to the alaskite that the latter has to the granite. The alaskite is a granite without biotite; the quartz is an alas kite without 

feldspar. The segregated quartz, as is shown elsewhere in this report, is in this case 

of the same age and generation as the granules of quartz which make up a large proportion of the alaskite and granite. 

The second class has probably segregated from the granitic magma in the manner above noted, but at a lower or slightly different locality, and has found its way 

into or near the granite, veinwise. 

The third class represents the work of similar magmatic juice, which has penetrated the intruded limestones and slates near the granitic contacts and has deposited 

silica and metals chiefly by the process of replacement. v 

The fourth class, which is believed to have had a similar origin to the first three, 

is valuable as illustrating a mineralogical connection between the gold veins in the 

granite and the silver veins in the limestone, and so favoring further the theory of 

common origin. 

The quartz veins in the limestone are marked by relative abundance of quartz 

with rather sporadic mineralization, while those in the granite are usually smaller 

and not so well defined, but frequently carry better values, at least near the surface. 

DIVIDEND TYPE • 

. The class of deposits due directly to segregation is illustrated by the Dividend 

and similar prospects. The Dividend lies near the center of the granitic area, within • 

a zone of alaskite 150 yards wide, which is itself intrusive into the granite and runs 

off several miles at least in a northwesterly direction. At the Dividend the alaskite 

contains small bunches and veinlets of quartz. These are irregularly distributed, 

having no definite trend and forming no definite vein. In the quartz and in the 

neighboring alaskite there is some original pyrite mainly oxidized to hematite. In 

both cases the pyrite is claimed to be auriferous. Some perfectly fresh alaskite was 

seen, which was claimed to be second-class ore, but an assay made for the writer by 

Mr. R. H. Officer showed traces only of gold and silver. Microscopic examination of 

this material shows a perfectly fresh and unstrained typical quartz-feldspar rock. 

A specimen of first-class ore, which is claimed to run up to $250 per ton whe~ sorted, 
88 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

was found to be alaskite similar in original composition to the fresh alaskite' just 

mflntioned, but with its feldspar entirely decomposed to sericite. In some of this 

ore free gold is visible, probably the product of oxidation of the pyrites. It is prob1\ble that there has been near the surface some enrichment by the process of oxidation. The values are all in gold.-

The alaskite here is fine and even grained and contains quartz and feldspar in 

about equal proportions. The feldspar is both orthoclase and striated feldspar 

probably albite. In form the feldspar is idiomorphic to hypidiomorphic, and the 

SW NE 

0 5 rofeet 

FIG. 35.-Sketch vertical cross section of prospect hole on Arroyo 

Grande claim, Windypah district. 1, Alaskite; 2, quartz, auriferous; dotted outlines show pit. 

quartz occupies interspaces. Sometimes the feldspar is broken into and 

separated by the intrusion of the 

quartz. Both of the above-mentioned phenomena indicate that the 

quartz crystallized as a rule decidedly subsequent to the feldspar. 

Some portions of the alaskite mass, 

as seen under the microscope, contain much more quartz than others, 

so that typical granular vein quartz 

results usually in parallel bands, this 

quartz being perfectly contemporaneous with the intergranular quartz 

of the quartz-feldspar rock. Besides the original pyrite, which is 

frequently found in the alaskite and 

also in the segregated quartz and 

which is altered to limonite or hematite, there are small specks of 

magnetite and occasionally some 

probably original crystals of hematite. Biotite is occasionally found, and a little sphene and zircon. In some cases 

the feldspar is partially altered to sericite, and sometimes it is entirely decomposed. f 

A quarter of a mile northwest of the Dividend, in the ·same alaskite dike, is a 

prospect called the Magpie, showing an open cut on some small q~artz lenses. The 

geology is the same as at the Dividend. Here the quartz veins are mixed in places 

with coarse feldspar, indicating their origin. The inclosing alaskite, when examined 

microscopically, is found to consist of quartz and feldspar in varying proportions. 

In some thin sections the contemporaneous crystallizc.,tion of quartz and feldspar 

is shown, which is unusual for this region. In some portions of a certain slide, for 

example, the feldspar is idiomorphic ; but in other portions the quartz has an idiomorphic tendency against the allotriomorphic orthoclase. As a rule, however, the 

feldspar is distinctly older, and in other slides the quartz is seen in the process of 

segregation, showing beautifully the genesis of segregated quartz veinlets (Pl. XXII). 

By this process typical vein quartz .forms in places, having near the edges frequent 

small idiomorphic crystals of feldspar, like those of the adjacent alaskite, entirely surrounded by the quartz. In these rocks also original pyrite is present. The feldspar • 
• 

PROSPECTS IN THE SOUTHERN HALF. 89 

consists of orthoclase and probable albite, and becomes turbid from sericitization 

or kaolinization. 

About 1,500 feet northwest of the Magpie, along the same alaskite dike, is 

another unimportant prospect called the Arroyo Grande. The alaskite here is more 

or less silicified and iron stained, with small areas of fine granular, quartzite-like 

segregated quartz. There are several quartz lenses, the largest observed being 1! 

feet thick and 6 or 8 feet long at this point, but they have no definite extension 

(fig. 35). The values here are said to be entirely gold. 

HECTOR TYPE. 

The Hector vein is a decomposed shear zone in the granite, about 1,000 feet 

away from the contact. This shear zone Is partially and irregularly occupied 

by decomposed, friable, and ironsw stained quartz. The walls of the vein 

are poorly marked. It has a strike of 

N. 45° W. and a dip of 60° SW., and 

was opened up at the time of the 

writer's visit by an incline shaft 55 

feet down (fig. 36). The granite of 

the walls is decomposed. It is a 

coarse, chiefly feldspar-quartz rock 

with little biotite. Some apatite, 

sphene, and magnetite are present. 

The feldspar is sericitized and kaolinized to a variable extent. The vein 

quartz contains scattered pyrite, and 

assays are reported to show values in 

gold, with only traces of silver. 

North of the Hector, on the same 

hill, are similar smaller veins, being 

stringers of pyritiferous · quartz in 

decomposed granite. They have a 

general west to northwest strike. 

Some of this material shows free 

gold. 

The Hunkidori prospect is located 

about 1,200 feet west of the Hector and 

FIG. 36.-Vertical cross section of Uector vein. 1, Q.uartz (ore); 

2, white decomposed granite; 3, gray partly altered granite. 

a little south, and is also in granite. This rock is a medium-grained biotite-granite, 

having a different texture from that at the Hector in that it contains very large 

feldspar phenocrysts. In this granite there is a crushed zone 2 feet wide, with no 

clean wall. It contains mixed quartz and iron-stained granitic material, the quartz 

being especially abundant near the foot wall of the zone. This vein is said to have 

gold values and to horn free gold. 

A few thousand feet southeast of the above prospect is another called the Richmond Chief. This is in granite of variable texture, changing from a granular form 

to one that is coarse and almost pegmatitic, with extremely largP feldspar phenocrysts. This granite contains areas of decomposed basic rocks which areprobably 

• 
90 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

dioritic dikes. A quartz vein cuts across the granite and is exposed for some distance 

along the hill. This is probably subsequent in origin to the diorite. In places this 

vein shows pyrite, largely oxidized, with some faint copper stains. It is said to assay 

gold. CHLORIDE TYPE. 

sw 

0 5 -feet 

FIG. 37.-Vertical sketch cross section of Chloride vein. 1, Alaskite; 

2, thin-bedded slaty limestone (altered); 3, silicified limestone (hornstone) and quartz containing metallic minerals (ore); outlines of 

prospect pit shown by dotted lines. 

• 
\ 

\ 

' PRO~PECTS IN THE SOUTHERN HALF. 91 

crossing the strata to anot er granite contact farther south. At several points along 

this vein zone prospects we e visited. At the northernmost locality, not far from the 

granite, there is a quartz V\ein several feet thick, sometimes brecciated, containing 

cavities left by the dissolut\ion of pyrite. The country rock is a metamorphosed 

slate, consisting chiefly of qu artz with fine lamellar green biotite, with some tourmaline, magnetite, epidote, and scattered crystals of dark red, probable rutile. There 

is a parallel and larger quarf.,z ledge 150 yards away from this one. Farther south 

along the same general zone,, at the Victoria prospect, there are small irregular 

stringers of quartz in metam1 orphosed slate. This quartz shows galena and copper 

pyrite, the latter partly altere!d to malachite and chrysocolla. The ore is said to contain gold and silver. Therei are chalcedony coatings on some of the cracks. The 

country rock here is like tha1G just described. Somewhat over 1,000 feet still farther 

southwest on this zone, at Lhe Fesler prospect, the character of the vein is like that 

last described. Some of tbte formation here is a knotted schist, which, when examined microscopically, provnd to be practically the same as the country rock farther 

north. The knotted portions are irregularly segregated bunches of biotite. 

From this point southward along the zone similar outcrops occur at several 

places. About It miles farther southwest is the Sib prospect. This shows a quartz 

vein about 4 feet thick, o·utcropping in an arc-shaped form for about 90 feet, then 

passing under the PleistcJCene drift on both sides. The vein has a general N. 55 o 

W. strike, and dips 65° NE. The country rock is white and brown crystalline 

limestone or dolomite. The property is opened up by a shaft 20 feet deep and a pit 

6 feet deep. The pit shnws nearly 4 feet of solid quartz, with limy streaks. In the 

shaft the quartz is found next to the unaltered country rock, and the solid portion 

of the vein is 1 foot thick, but is not persistent, fading away above and below. This 

w:eakening and dying outo indicates that the veins have originated largely by replacement. 

These veins contain, scattered in the quartz gangue, small bunches of metallic 

mineral. Galena is often present, and chalcopyrite, the latter usually largely altered 

to black massive secondll, ry oxides or sulphides. The most important ore mineral, 

however, is dull black aL d massive. It is usually partly altered to red and blue 

copper minerals, probably both carbonates and silicate (malachite, azurite, chrysocolla), and it is perhaps on this account that even where the alteration is not 

perceptible to the eye the mineral gives a greenish streak. This material is highly 

argentiferous, and is usually called by the miners "black metal." It also contains 

gold. Specks of free gold v'ere observed in one of the specimens collected. Dr. 

W. T. Hillebrand, who examined this mineral, found that it consisted principally 

of some of the oxides of antimony, colored by undecomposed sulphide. This sulphide 

may be either a residual port ion of an original copper-antimony-silver sulphide or 

may be some secondary sulpfilde. The silver, of which considerable is present, is 

not in the form of chloride, ¥)ut whether as sulphide or antimonate was not determined. The material is evidently partly oxidized and altered from its original condition. The margin of blue·-green copper staining around the areas of the black 

mineral shows that the latter has lost some copper; while the antimony and silver 

would be less likely to have been removed. The original material was probably a 

sulphantimonate or sulphantimonite of copper and silver. In its present form the 
92 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

mineral appears very similar to stetefeldtite, a substance that has been described 

from various of the older mining camps of Nevada, such as th~ Empire and Philadelphia districts, though probably not containing as much silver as the latter.a 

Analyses ·show that stetefeldtite is a mixed oxide and sulphide and probably an 

alteration product. Materials more or less similar to stetefeldtite have been 

described. as due to the alteration of sulp:Q.ides. The most likely original sulphide 

from which such an alteration material as the Silver Peak ore under consideration 

equid come is argentiferous tetrahedrite; and the material described as stetefeldtite 

.rriay have had a.similar origin. 

One assay from this prospect is said to have yielded 1,186 ounces of silver, 31 

per cimt copper and 3.8 dunces gold. This was probably pure "black metal." 

CONFIDENCE TYPE. 

The Confidence prospect is located nearly 2?! miles soutJtwest or the Sib. It 

shows a persistent vein 6 or 8 inches thick, with granite on both walls, that strikes 

N. 87° E., dips 78° S., and has been traced for 2,000 feet. The quartz is iron stained 

and shows cavities left by the dissolution of,pyrite .. It also contains small spots of 

coarsely crystalline galena; also some "black metal" or copper-silver sulphide. At 

some places the quartz is mixed with much jasper, and chalcedony coatings line 

cavities. Secondary cerussite, malachite, etc., occur. The values in this prospect 

are said to be chiefly gold, but on account of the mineral constituents it forms ·an 

interesting link between the veins of the Hector type and those of. the Chloride type. 

Over 2 miles north of the Confidence is the Widow prospect, in coarse granite cut 

by altered diorite. The diorite now consists entirely of secondary minerals, such 

as epidote, quartz, and broW11-green biotite. The vein lies on the under contact 

of the diorite dike with granite and has a strike N, 85° W., nearly parallel to that 

of the Confidence~..__J'he dip .is 34 ° south. The vein is fairly rJ'gular, a foot or 14 

inches in thickness, but in places opens out irregularly to as much as 3! feet (fig, 38). 

It is said to carry considerable values of gold and a very-little silver. The ore shows 

more or less decomposed pyrite and chalcopyrite, with some probable "black metal." 

The chalcopyrite is altered to malachite, and in part also probably to black copper 

oxide. · ' · 

PALMETTO DISTRICT. 

The portion of this district comprised within the quadrangle lies· in its southeastern part, on the n9rth slope of the Pa.lmc,tto Mountains. In the same general 

region are more important districts -which, since they are outside of the area examined, were not visited and are not described. 'J.'hey lie south and southwest of the 

district which has· been investigated. The deposits within the quadrangle are all 

prospects,· and are in and !).ear a body of intrusive granitic rock, with aplitic facies, 

which cuts the Paleozoic sediments. The geological conditions and the nature of 

the ores ai:e very similar to those in the Windypah district. 

a Dana, ,E •. I>., System of Mineralogy, 6th ed., p. 204. 
PROSPECTS IN THE SOUTHERN HALF. 93 

MACNAMARA. 

The MacNamara group of prospects is located near Indian Garden, on claims 

located by Matthew MacNamara in 1880. The two principal claims are the Bullion 

and Mammoth. Assessment work was done upon these for twenty years, but there 

has been no real production. In the spri:hg of 1903, Messrs. Lynch and O'Meara, 

of Tonopah, worked the prospects somewhat on a bond, but did not take it up. 

This deposit is situated not far from the contact of the main granitic intrusion, 

in a locality where the calcareous and siliceous sediments are cut by a complex of 

alaskite dikes, which probably represent a later phase of the granitic intrusion. 

Although quartz with some copper staining and considerable iron is found at various 

points in the intruded sediments, generally in streaks having a northwesterly direcs N 

FIG. 38.-Vertical cross section at Widow prospect, showing relation of vein to greenstone dike. Dotted lines show outlines 

of incline. 

tion, only the one vein opened up in the above-mentioned prospects has developed 

any quantity of ore. Where this vein is most productive it consists of quartz, 

replacing and penetrating the altered calcareous sediment on the under side of an 

alaskite dike. 

The unaltered impure limestone of this region is rather thin bedded and light 

blue, with cherty bands. Within the area cut by the alaskite dikes it becomes 

metamorphic, showing silicification, in extreme cases leading to the production of 

hornstone or jasperoid and also containing garnet and epidote. In some of the 

garnet-bearing bands are white quartz veinlets, which have apparently the same 

origin as the other metamorphic minerals. A number of thin sections of these 

• 
94 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

metamorphic sedimentary rocks were examined microscopically. One, which 

appears to be an altered shale, is now composed chiefly of fine cherty quartz, sericite, 

chlorite, and garnet, with accessory magnetite, orthoclase, and tourmaline. A 

number of other thin sections showed variations of a single kind of metamorphic 

rock, consisting chiefly of quartz, with abundant clear, translucent, greenish garnets, 

which often show beautiful optical anomalies. Sometimes dark-brown opaque 

garnets of smaller size, of a different variety from that mentioned, are abundant. 

In the garnet in every case are abundant tabular crystals with a moderately high 

single and double refraction. In some cases these are colorless, in other cases they 

are red, and still others green, or the red and green coloring may be mottled. In 

certain crystals where the coloring matter is bunched or segregated, however, the 

red coloring is seen to be due to disseminated hematite and the green coloring to 

disseminated chlorite. The mineral is probably malacolite. Other constituent 

minerals are magnetite, calcite, and in some cases muscovite. A metamorphic 

rock of different variety is fine grained and consists mostly of quartz, epidote, and 

brucite, with some zircon. 

The vein which has been prospected is locally strong, but has no good walls 

and is rather weakly mineralized. The outcrop is marked by frequent bunches of 

brown jasperoid. It is also marked by a conspicuous red iron-stained zone running 

N. 50° W. for an observed distance of half a mile, and probably farther. The prospect is opened by a shaft 100 feet deep on the vein and by three adit tunnels, 

the lowest and longest of which runs in 230 feet to the vein and a little distance 

beyond it. The vein as opened in the workings shows 10 feet of ledge matter, 

consisting of cracked and decomposed limestone. In this are irregular streaks of 

quartz, some of which show galena, chiefly coarse grained, with lead carbonate 

and some slight malachite stains. It has also a little pyrite and chalcopyrite. The 

gangue is quartz. Some barite is reported, but was not observed by the writer. 

The best of the ore, carefully sorted out, is estimated by a local prospector to yield 

about $50 to $80 per ton, the values consisting of $2 in gold, 80 ounces in silver, and 

the rest lead. Mr. H. W. Turner had some of the galena from this mine assayed, 

which showed $11 in gold, 54 ounces of silver, and 76 per cent lead. 

The alaskite dike along whose under surface the vein runs is about 10 feet thick. 

Examined microscopically, the rock was found to be decomposed, the original feldspar being represented by masses of fine sericite. In some places the original quartz 

showed a tendency to be strung along in chains. Some limonite, seen in the thin 

section, was probably due to the oxidation of original pyrite. 

The crushing which formed a channel for the mineralizing solutions that deposited the vein was very likely accomplished at the time of the alaskite intrusion and 

perhaps by its agency. This will explain the localization of the vein along the 

alaskite dike, which is a relation similar to that observed for similar veins in the 

Windypah district. Some of the movement, however, appears to have been subsequent to the alaskite intrusion, and the alaskite itself is in places partially affected 

and is frequently decomposed. 

A dike of fine altered diorite, of the familiar type noted in. all other mining districts in this quadrangle, was observed in this neighborhood, but has no connection 

with the principal prospect or with the veins in general. 
PROSPECTS IN THE SOUTHERN HALF. 95 

PAYMASTER ZONE. 

This is shown on the map as a long zone of veins, all probably occupying the 

same fracture zone, but not known to be entirely connected. The entire extent is 

about 4 miles, and part of the zone lies in granite or alaskite and part in the intruded 

sediments. The general strike is west-northwest, parallel to the long axis of the 

granitic intrusion. 

The westernmost part of the zone visited is that where the Nevada and California 

claims are located. These were located in 1880, and, having lapsed, were relocated 

in 1903. The veins lie in alaskite, which constitutes a considerable mass on the 

border of the granite. A specimen of the alaskite from the wall of a vein at one 

point was found to be quite fresh, consisting of quartz and feldspar in about equai 

proportions. The feldspar shows a tendency to idiomorphism, while the quartz is 

subsequent. In some cases the quartz cuts across the older feldspar. Quartz grains 

have a tendency to segregate in connected and elongated areas; definite quartz veinlets may thus result. The straight walls for part of the course of such veinlets 

indicate that the mass was in part brittle enough to be fractured and forced asunder 

even while the crystals of the quartz veins were filling the interstices between the 

feldspar crystals. A connecting spongy mass of contiguous feldspar crystals is thus 

evidenced, saturated with the residual magma which deposited the quartz. The 

feldspar here is orthoclase, microperthite, and oligoclase-albite. There is accessory 

zircon and magnetite. Another specimen of the alaskite taken from the vein wall 

at a different locality was similar but was altered, the feldspars having changed to 

very fine sericite. 

On the whole the quartz veins are slightly later locally than the alaskite, but the 

relations indicate that the quartz has segregated from the alaskite. The separate 

quartz bodies along the vein zone are not persistent, often running into portions 

which become mixed with feldspar and appear to give way to alaskite. The thickness of the quartz is variable, but it attains a maximum of several feet. On the outcrop the "ridges of quartz are offset one from another, and both this and the observed 

fact that the quartz may diminish in thickness g_oing down, as observed in a small 

incline here, indicate that the quartz bodies are roughly lenticular in form. 

The quartz shows copper and iron pyrites. The values are said to be in gold, 

but to be low. In one place the highest assay is said to have been $6 in gold, while 

at anotherpicked samples are said to have gone from $10 to $30 in gold .. 

The Reli:;tnce is another abandoned property, on the same trend as the California 

and Nevada and about 1 mile east of these claims. The Reliance and the adjoining. 

Helpmeet claims are located on an east-west striking lode zone in alaskite and granite 

A specimen of the granite here is coarse grained, containing quartz, orthoclase, oligoclase, microperthite, biotite, ilmenite, and sphene, with some chlorite secondary to 

the biotite. The order of crystallization has been (1) oligoclase and orthoclase, (2) 

orthoclase and quartz. The oligoclase is sometimes included in the orthoclase, and 

an inner growth of oligoclase is sometimes completed by an outer zone of orthoclase. 

At one point here a vein 15 feet wide is opened by an incline 30 feet down. 

The gangue is quartz and barite, carrying some copper pyrite largely altered to black 

copper oxide and malachite. 
96 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

By following the trend indicated by the above-mentioned lodes, what is apparently a further extension, covered by the Paymaster, Porto Rico, and Richmond 

claims, may be reached. These lie not in the granite but in the metamorphosed 

calcareous sediments into which the granite is intrusive. Of these prospects, the one 

lying farthest east is the Paymaster. There was an old location here made ten or 

twelve years ago, called the Mountain Lion, but this having lapsed it was relocated 

in 1902 by E. H. Rose. From here east and west along a zone 4,000 feet long or 

more, there is a weak lead marked at intervals by large masses of black hornstone, 

specular iron, garnetiferous and rather coarsely crystalline metamorphic rock, and 

associated quartz veinlets. Crystalline limestone appears at many points along the 

zone. The quartz, which is present in rather small quantities, is iron stained, and 

some of it is said to yield gold on horning. The lead seems to be a long band in the 

metamorphosed sediments, marked chiefly by a special segregation of quartz and by 

some gold. It is probable that the lead may follow a fault or fracture zone, for at 

one point on the Paymaster claim a shaft 40 feet deep shows a decomposed, soft, 

ground-up material containing rounded pebbles which probably owe their origin 

:to attrition. This soft material is said to be the best gold ore, some of it carrying 

$40 in gold, but very little silver. Some of the whiter quartz, copper stained, is said 

to carry some silver. 

Specimens of the metamorphic rock along this zone were examined microscopically. One is a dense hornstone, which under the microscope proves to be in 

part a dense carbonaceous chert. Interstratified layers in this contain probable 

orthoclase, greenish garnets, and abundant probable malacolite, with fine carbonates, 

quartz, hematite, epidote, and :.wisite. Another specimen is mostly diopside, largely 

altered to calcite and serpentine, with iron and some quartz. Other primary minerals are magnetite, quartz, orthoclase, albite, and zoisite. 

At on.:l place a 2-foot dike of basaltic diabase cuts the metamorphosed strata. 

This consists of partly altered feldspars and colorless augite. 

BARREL SPRINGS. 

At Barrel Springs the writer noted in 1899 a that the limestone is decomposed 

along a vertical zone 10 yards wide and stained with iron and copper. The rocks 

here have a honeycombed and cavernous appearance. Mr. H. W. Turner took at 

this point a sample of a piece of siliceous rusty material which assayed $1.24 in 

gold and 11 cents in silver per ton. A little copper pyrite was noted. 

AURIFEROUS SAND DUNES. 

Of the areas of sand dunes shown on the map, that occupying the center of the 

south side of Clayton Valley is the largest. This consists of typical white sand, with 

no vegetation. In detail the sand is continually shifting, but the general position 

of the dunes is said not to change materially from year to year. The dunes have 

been several times staked out and assayed with the idea of cyaniding the material 

for gold which it is supposed to contain. 

These dunes may be considered to represent a rough average sample of all the 

quartz in the district, including that from the veins, from the granitic rocks, and 

a Bull. U.S. Geo!. Survey No. 208, p. 186. 
AURIFEROUS SAND DUNES. 97 

from the rhyolites. Since the quartz veins weather largely in small, heavy fragments, and since the granite yields small grains, it is probable that altered rocks furnished by far the larger proportion of this sand. From all sides-north, east, south, 

and west-the detritus pours down from the mountains into the Clayton Valley basin. 

It is partly sorted by water, but chiefly by wind, which has blown away the fine particles derived from the decomposition of the aluminous minerals and left the quartz 

clean, and, having collected it from all over the valley, has piled it up in these heaps. 

Information concerning the reputed gold contents of the dunes was obtained 

from Mr. F. A. Vollmar, of Silver Peak. Mr. Vollmar says he first sampled these 

sand dunes several years ago, and eight assays gave him an average of $1.80 per ton, 

while some were as low as 40 or 50 cents. Later other parties sampled the dunes 

thoroughly and 1,500 assays were made, for which an average of $1.50 per ton was 

claimed. The matter, however, was dropped. Later Mr. Vollmar took sixteen 

assays for another party and got only traces of gold. Still later two other samples, 

collected by another person, were assayed by Mr. Vollmar, giving again only traces. 

Mr. Vollmar advances the explanation that the first high assays may be due to 

material which was derived from the tailings from Chiatovich's mill at Silver Peak, 

particles of gold having wandered across to the sand dunes along with other windswept material. The present writer took a large sample of the sand from the 

northern end of the dunes, which was assayed by R. H. Officer & Co., of Salt Lake 

City, and gave only traces of gold and silver. 

From the shifting movement continually going on within these dunes, it is 

likely that the lower portions may contain more gold than the rest. 

13002--~o. 55--06----7 

• 
PLATE XVI. 

THIN SECTIONS SHOWING SEGREGATION OF QUARTZ AND ALASKITE INTO BUNCHES. 

A, SegregRtion of mn,gmatic quartz (and also of feld8par) and alaskite into comparatively large bun~hes. Feldspar is chiefly orthoclase; the quartz is suhseqmmt and intrusive into the feldspar crystals, yet is an essential part of the rock fabric. Light portions are quartz (q); dark portions fPldspar (f). SpPcimen 

163, from cross-cut tunnel of Mary mine. Photograph o!' thin section as viewed Rgainst a clear sky. 

Tho feldspar being largely altered to sericite becomes semiopaque; enlarged 4 diameters. 

B, Segregation of magmatic. quartll and alaskite into bunches of varying sizP. Light portions quartz (q); 

dark portions feldspar (f). Specimen 164, from cro~s-cut tunnel of Mary mine. Photograph of thin 

section as viewed against a clear sky. The feldspar is somewhat altPred and so becomes semiopaque; 

enlarged 4 diameters. 

98 
U. 8. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 55 PL. XVI 

A 

B 

T HIN SECT IONS SHOWING SEGREGATION OF QUARTZ AND ALASKITE INTO BUNCHES. 
CHAPTER III. 

GENETIC RELATIONS OF ~1ETALLIFEHOUS OHE DEPOSITS. 

THE DRINKWATER TYPE OF GOLD MINES OF MINERAL RIDGE. 

OCCURRENCE OF GOLD IN QUARTZ. 

The typical auriferous quartz of Mineral Ridge is white and crystalline and is 

seen under the microscope to be crowded with liquid inclusions. Its appearance 

and nature is that of the characteristic gold quartz found in so many districts in 

the world. Occasionally this quartz contains original muscovite and rarely original 

chlorite crystals. Contemporaneous sulphides are sparsely disseminated, principally pyrite, more rarely galena. Occasional copper pyrite has been observed. 

The quartz throughout contains gold and a little silver, the proportion of the latter to the rormer being about 1 to 100. The gold is finely disseminated in the free state 

through the quartz and is also contained in the scattered sulphides. It is estimated 

that about 87 per cent is in the free disseminated form and about 13 per cent in the 

sulphides. The gold values are irregularly concentrated into certain groups of 

lenses and certain lenses within those groups. Thus in some portions it is relatively 

high grade, while other portions are low grade or nearly barren. 

RELATION OF QUARTZ TO QUARTZ-FELDSPAR (ALASKITE) ROCKS. 

The quartz lenses are intimately associated with alas-kite intrusions on Mineral 

Ridge, one not occurring without the other. Petrographically the typica] quart7; 

and the typical alaskite form two ends of a rock series, between which every gradation is abundantly represented. The alaskite and quartz have very nearly the 

same dense, milk-white appearance, and even on the outcrop it often requires close 

scrutiny to determine the difference between the two. The alaskite becomes quartzose and passes to a state where it contains quartz blotches and veinlets (Pl. XVI, A, 

B, and Pl. XVII, A), and so gradually passes over into typical vein quartz. Nearly 

every quartz lens which has been mined or prospected shows in places considerable 

feldspar mixed with the quartz. The auriferous quartz frequently runs off laterally 

into alaskite, chiefly pegmatitic. As a rule, the contained gold grows rapidly less 

with incoming feldspar, although occasionally feldspar-bearing rock carries good 

values. Under the description of the Frank No. 2 prospect, the occurrence of 

primary free gold in pegmatite has been described. Also, in one place in the Hickey 

tunnel, a small bunch of sulphide-bearing quartz segregated in the midst of pegmatite showed on assay the relatively high result of $76 in gold. The Golden 

9? 
PLATE XVII. 

THIN SECTIONS SHOWING MAGMATIC QUARTZ AND GKEISSOID STRUCTURE IN ALASKITE . 

.A, Veinlets of magmatic quRrt:r. in fine-~rained alaskite. Light portions quartz (q); dark portions feldspar (f). 

SpPcimen 2R8, alaskite in quartz vein, Nevada prospect, Palmetto district. From photograph of thin 

section as seen against a dear sky, withont microscope. The fPldsparis altered and turbid and is hence 

semiopaque; enlarged nearly .5 diameters. 

B, Original gneissoid structure in uncrushed alaskite. Light portions quartz (q); dark portions feldspar (mostly 

orthodase, less finely striated feldspar). Specimen 172, from dike in canyon below Drinkwater mine. 

Fro::n photograph of thin section as seen by transmitted light against the sky without the microscope. 

The feldspar (f) being somewhat turbid from weathering is semwpaque: enlarged 5 diameters. 

100 
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B 

THIN SECTIONS SHOWING MAGMATIC QUARTZ AND GNEISSOID STRUCTURE IN ALASKITE. 
DRINKWATER TYPE OF GOLD MINES. 101 

Eagle ore lens, which is said to average $18 to the ton, also contains a good deal 

of feldspar throughout. This lens contains small streaks of segregated quartz 

with primary pyrite and galena. 

NATURE OF GRANITIC MAGMAS. 

It was long ago recognized that granitic rocks had originated from magmas 

essentially different in nature from those which form the more basic plutonic rocks 

and from those which produce surface lavas. The relative order of crystallization 

and the nature and association of the chief granitic minerals are decidedly against 

the explanation of cooling from a simply fused condition. 

The relative order of crystallization in granites is (1) ferromagnesian minerals 

(chiefly biotite and hornblende), (2) feldspar, and (3) quartz. Of these quartz, 

the last to crystallize, is the least fusible. Hornblende can ordinarily not be formed 

at a great heat and at a sufficiently high temperature passes over into pyroxene. a 

Biotite on elevation of the temperature is fused to a glass. The contradiction 

between the fusing points and the relative order of crystallization is clearly seen 

in the case of the feldspar and quartz. According to V ogt b the fusing point of 

orthoclase is 1,190° C., of albite 1,140°, of quartz 1,700° to 1,800°. 

Many granitic.minerals when the granite is heated red hot change their optical 

properties, showing that they were formed at a relatively low temperature; under 

such conditions they often decrepitate." 

The experimental reproduction of granitic minerals has thrown further light 

upon the condition of the rock's crystallization. Quartz, orthoclase, microcline 

anorthoclase, albite, muscovite, and amphibole have never been artificially formed 

by the cooling of dry melts, in spite of many attempts. All these, however, have 

been formed artificially in the presence of "mineralizers," such as water, fluorides, 

boron compounds, tungstic acid, etc.a 

Above a certain high temperature, but before the melting point is reached, 

quartz passes over into other opal-like modifications of silica. e 

Muscovite is not a volcanic mineral.! It is not found in any of the plutonic 

rocks save in granites, nor is it present in the volcanic rocks whose chemical composition corresponds to that of the granites. When subjected to heat, it fuses to 

a glass, showing it has been formed in the wet wayJ' According to Braunsh 

mica can easily be formed by melting a mineral containing its elements with a 

metallic fluoride under 800°. At higher temperatures mica is unstable and passes 

over into olivine, augite, scapolite, etc. In this case fluorine shows its property 

of being able to crystallize amorphous substances.i That the presence of this ----·-----·--------·----------------. 

a Vogt, J. H. L., Mmeralbildung in Silikatschmelzlosungen. Christiania, 1903, pp. 6 and 7. Hornblende has been formed 

by long heating wtth water at 550° C. Above 500° to 700° augite is formed mstead of hornblende. 

b Op. cit., pp. 141 and 190. 

c Bischof, Gustav, Lehrbuch der chemischen und physikalischen Geologie, vo!. 2, pp. 865 and 866. 

a Brauns, Reinhard, chemische Mineralogie, p. 245. Vogt, Mineralbildung in SilikatschmelzlOsungen, Christiania, 1903, 

p. 6. 

e Bischof, Chern. und phys. Geologie, vo!. 2, pp. 866 and 868. 

t Rosenbusch-lddmgs, Mwroscopical Physiography of the Rock-Making Minerals, 2d ed., p. 264. 

g Zirkel, Lehrbuch der Petrographie, 2d ed., vo!. 1, p. 340. 

h Chemische Mmeralogte, pp. 247, 248. 

• Doelter, C., Allgememe chemische Mineralogie, p. 176. 
PLATE XVIII. 

ORIGINAL PYRITE IN GRANITIC PHASE OF ALASIUTE. 

A, Original pyrite in granitic phase of Llaskite associated with magnetite !ilmenite'?) and pyrite. Drawing 

from thin section 165, granitic phac:e of ala,kite from Mary tunnel. b, Biotite; rn, magnetite (ilmenite 1); 

p, pyrite. Enlargement about fiO diameters. 

MUSCOVITIZED ORTHOCLASE CRYSTAL INCLOSED IN FRESH ORTHOCLASE 

B, Older idiomorphic orthoclase crystal partly altered to fine muscovite and inclosed in fresh, unaltered orthoclase of the second period of consolidation. Drawing from thin section 184, fresh alaskite from the Vega 

prospect. Illustrates formation of muscovite by the action of the residual magma on earlier formed 

feldspar during consolidation. Enlarged about 180 diameters. 

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U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 55 PL. XVIII 

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B 

A. ORIGINAL PYRITE IN GRANITIC PHASE OF ALASKITE. 

B. MUSCOVITIZED ORTHOCLASE CRYSTAL INCLOSED IN FRESH ORTHOCLASE. 
DRINKWATER TYPE OF GOLD MINES. 103 

mineralizer is essential to the formation of natural as well as artificial muscovite 

is indicated by various facts. The best crystallized muscovite occurs abundantly 

in cavities in granites and in pegmatites, associated with minerals like tourmaline, 

which is the result of the action of another mineralizer-boron. a Fluorine is also 

present in the composition of muscovites. On heating muscovite gives off water, 

which reacts for fluorine.· According to Bischof, b the best characterized micas, 

for example, those from granite, are richest in fluorine. 

Finally the contact metamorphism which intrusive granitic rocks exert upon 

the rocks which they cut is of such a character as to show the presence of mineralizers. Minerals like tourmaline, scapolite, muscovite, etc., frequent in the contact 

metamorphic aureoles of granites, testify to the emanation of boron, chlorine, 

fluorine, water, etc., from the consolidating granitic magma, these mineralizers leaving the magma and playing the same crystallizing role in the intruded rock that 

they have already played in the formation of the granite. 

From these considerations it is plain that ordinary granitic rocks have crystallized 

at relatively low temperatures, which, from the experiments made in the product;on 

of granitic minerals, we can suppose as having a maximum of 500° to 800° C., and 

that at such temperatures, which are below the fusing point of most of the granitic 

constituents, the granite magma remained mobile on account of the intermixture of 

water and other mineralizers. In this process it is likely that water was one of the 

most abundant and efficient factors. From analysis of the fluid inclusions in 

granitic quartz we know that these inclusions, which represent the final fluid residual 

from the consolidation of the granite (since quartz is usually the last mineral to 

crystallize), consist mostly of water with alkaline salts and carbonic acid. The 

quantity of water in the magma has never been even approximately determined. 

Scheerer c estimated it as between 1 and 50 per cent, hut believed that the actual 

quantity approached much nearer the minimum than the maximum of these figures. 

NATURE AND COMPOSITION OF THE ALASKITE. 

The alaskite of Mineral Ridge is made up essentially of quartz and feldspar, 

with some muscovite. Its structure is variable. In general it may be described as 

allotriomorphic granular or granitic, but it varies frequently on the one hand to fine 

grained or aplitic and on the other to coarse grained or pegmatitic. It sometimes 

has a parallel banding or gneissic structure, which is original. (Pl. XVII, B.) The 

feldspars consist of orthoclase, microcline, anorthoclase, albite, and oligoclase-albite. 

All of these except anorthoclase are present in nearly every section. Rarely andesine-oligoclase has been identified. Muscovite is usually present in small amount 

and in small flakes. Accessory minerals frequently found are zircon, pyrite, and 

calcite. "rn one place alaskite pegmatite was found to contain, apparently, arsenical 

pyrite. By the accretion of sparse biotite the alaskite passes into a granitic phase. 

(Pl. XVIII, A.) On the other hand, by the withdrawal of the feldspar it passes into 

a common quartz phase. Where biotite 1s present, additional accessory minerals -----------------------

a Dana, E. S,. System of Mineralogy, 6th cd., p. 616. 

b Chern. und phys. Geologie, vol. I, p. 79. 

c Bulletin Societe Geologique de France, 1846-47, 2d ser., IV, 1, p. 490. 
PLATE XIX. 

THIN SECTIONS SHOWING CHAIN-LIKE ARRANGEMENT OF QUARTZ GRAI~~S IN 

A.LASKITE. 

A, Chains of magmatic quartz grains in alaskite, the beginning of vein-like structures; "• feldspar (chiefly 

orthoclase) almost Pntirely alt,ered to fine muscov1te (sericite); m, fresh microcline; q, quartz. Micro· 

photograph of thin section of alaskite (specimen 64), wall rock of auriferous quartz in Hickey tunnel 

workings, Drinkwater mine. Magnified 11 diameters. 

B, Grouping of magmatic quartz grains in chains; the beginning of vein-like segregations of quartz; o, orthoclase, either clear or slightly altered to sericite; m, clear microcline; q, quartz; a, striated feldspar, not 

determined. Microphotograph of granitic alaskite (specimen 103) from Vanderbilt mine. Magnified 11 

diameters. 

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U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 55 PL. XIX 

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B 

TH I N SECT IONS SHOW I NG CHA I N-LIKE ARRANGEMENT OF QUA RTZ GRA I NS IN ALASK ITE. 
DRINKWATER TYPE OF GOLD MINES. 105 

have been noted-such as apatite, magnetite, sphene, probably ilmenite, and 

tourmaline. 

Microscopical study of thin sections shows that the crystallization of the 

alaskite was slow and interrupted. Two distinct periods or generations of crystals 

are always represented. In different sections the nature and relative amounts of 

the minerals belonging to each generation varies greatly, but the following general 

observations apply to all cases: 

1. Quartz is usually absent from the first generation, or, if present, is subordinate. In the second generation it is always predominant. In some cases the first 

generation may be entirely of feldspar and the second entirely of quartz, but the 

separation is usually not so marked, some of the feldspar crystallizing with the 

second generation together with thepredominant quartz. 

2. Microcline is almost always of the second generation. Very rarely does it 

enter into the first. 

3. Albite and oligoclase-albite occur generally in the first and second generations. 

4. Zircon and pyrite have been noted included in the minerals of the second 

generation, but not in the first.a 

In some cases the rock is almost entirely made up of crystals of the first generation, with the second generation represented in a very subordinate way. Other 

sections show the first generation only as scattering idiomorphic crystals, with the 

second generation making up the greater area. In most cases, however, the division is fairly equable. 

The chief lesson taught is that the quartz is slightly but distinctly younger 

than the feldspar. It is frequently segregated into irregular chains of grains which 

lie between bands of more feldspathic material. (Pl. XIX, A and B.) The later 

generation cements the interstices between the idiomorphic crystals of the first 

generation or invades these crystals along cracks. Sometimes these crystals are 

considerably broken, indicating some slight disturbances in the magma in the 

interval between the first and second crystallizations. (Pl. XX, A.) 

Fresh crystals of calcite are sometimes inclosed in fresh feldspar of the second 

generation, which also incloses zircon crystals. In this case the calcite as well as 

the zircon is plainly a magmatic formation which crystallized before the latest 

feldspar. 

In nearly every section muscovite is present, generally in fine fibers. In most 

cases this muscovite has evidently formed at the expense of some of the feldspar, 

and on casual observation it might be summarily disposed of as secondary sericite. 

Sericite is a term used for the fine variety of muscovite which is especially common 

as an alteration product; but the name applies only to the form and habit and not to 

the mineral, which is identical with the larger crystals. For this reason, as already 

a Brogger, W. C. (Mineralien der Syemtpegmatitgange, Zeitsch. fiir Kryst., p.164), places pyrite and other sulphides in 

pegmatite dike veins among the minerals formed at the second penod of consohdation, when the action of water and other 

mmeralizers was more potent in forming minerals than during the first period of consolidation, which was that of ordinary 

magmatic solidification. He also (p. 161) notes that while zircon IS formed during the first period, it is highly probable that 

it IS tormed by the action of mmeralizers, probably Ouonne; and it also occurs (p. 164) among the minerals of the second 

period. A. La Croix (Nouvelles Archives du Museum, Paris, 1902, Tome 4, p. 86) describes, in an alkaline granite from Madagascar (frequently pegmatitic) allotriomorphic or idiomorphic ztrcon inclosed in the quartz, sometimes in the feldspar. He 

regards this zircon as later than all the minerals except quartz. It is distributed in the granite, and not localized in veins. 

He regards it as the product of emanatiOns contemporaneous with the final consolidation of the rock. 
PLATE XX. 

THIN SECTIONS SHOWING TWO PERIODS OF CRYSTALLIZATION IN ALASKITE. 

A, Two generation" of crystals in alaskite fabric. First gPneration consists of feldspars largely altered to fine 

muscovite (partly sericite); s, orthoclase partly altered to fine muscovite (sericite); a, andesineoligoclase partly altered (less than orthoclasP) to fine muscovite. Second generation consists of clear 

unaltered feldspar and quartz; o, fresh orthoclase; m, fresh microcline; q, quartz. Note frequent idiomorphic crystals of first generation (e. g., the two altered orthoclase crystals marked s'). Note also the 

frequPnt irregular intrusion of crystals of the first generation by the minerals of the second genpration 

(as shown, c. g., by the quartz tongue q', q'). The alteration of tho earlier feldspar to fine muscovitn is 

believed to have taken place after the crystallization of the first generation and before that of the second. 

From microphotograph of thin section of alaskite (specimen 109) from Frank No.2 prospect; magnified 

11 diameters. 

B, Alaskite showing the first generation, comisting of feldspar (probably mostly orthoclase), and a second generation, consisting of quartz with a little microcline. The spcond generation of quartz cuts into and 

breaks vein-like ncross the older feldspar. Note especially the feldspar grain at bottom of illustration, 

which is broken into and separated by a vein-like arm of quartz. Light portions are quartz (q), with a 

little clear microcline; dark portions feldspar (f). Specimen 70, from HickPy tunnel workings, Drinkwater mine (wall rock of nuriferous vein). F10m photograph of a thin section viewed against a clear 

sky; the feldspar being largely altered to sericite and kaolin becomes semi opaque; enlarged 4 diameters. 

106 
U, S. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 55 Pl. XX 

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THIN SECTIONS SHOWING TWO PERIODS OF CRYSTALLIZATION IN ALASKITE. 
DRINKW A'l'ER TYPE OF GOLD MINES. 107 

stated in a previous publication,a the writer prefers to use the term muscovite 

throughout, there being in many cases no more need or advisability for two terms 

than there is of using a separate term for ordinary coarse crystalline quartz and for 

the fine-grained variety commonly encountered in thin sections as the result of 

secondary processes. 

The fact, however, that this muscovite has formed only at an expense of the 

feldspars of the first generation, while those of the second generation are clear, lends 

it at onee an extraordinary interest. (Pl. XX, A; also Pl. XVIII, B.) The earlier 

formed feldspars contain fine muscovite, whose distribution along cracks, cleavages, 

and along their peripheries shows beyond a question that the mica is subsequent to 

the feldspar and formed at its expense. Occasionally the feldspar is largely or even 

entirely transformed into a mat of fine muscovite fibers. In size these fibers, 

however, vary greatly, increasing from the fine sericitic variety to coarser and 

coarser phases until blades of crystalline muscovite are reached which are relatively 

small in proportion to the size of the other minerals, but are nevertheless characteristic granitic muscovite. Such muscovite crystals, included as they usually are in 

the feldspar, would ordinarily be interpreted as earlier formed crystals which have 

been included in the subsequently consolidated feldspar, but the invariably perfect 

transition from these to the sericitic variety shows that all have a common origin, 

which is the secondary origin above stated. 

From study of numerous sections the following general points in regard to the 

muscovitization are learned: 

1. The microcline is always clear and subsequent to the muscovitization. 

2. The quartz is almost always clear and subsequent to the muscovitization, 

but sometimes incloses fibers and blades of muscovite. 

3. The orthoclase and striated feldspars (chiefly albite and oligoclase-albite) 

are in part muscovitized and in part clear, as is natural from their belonging to both 

generations. 

From this it will be seen that the partial alteration of the feldspar into more or 

less fine-grained sericite took place when the magma was partially consolidated and 

before the deposition of the remainder which formed the second generation. 

These different observations show that the crystallization process of the alaskite 

magma was slow, so that i'1 many cases the magma became filled with contiguous 

1diomorphic feldspar crystals qf th-e first generation, the interstices between which 

were filled with the residual fluid. The first generation of crystals was rigid enough 

to be partly cracked and fissured in places, and in these cracks and fissures, as well 

as in the interstitial spaces between the crystals, the residual. fluid solidified. The 

study of the alaskites indicates that many of the fissures were formed by contraction 

consequent upon partial consolidation. Others seem to have been due to movements 

brought about by pressure on the still viscous magma. Thus the quartz, which 

makes up always the chief part of the second generation, besides forming as intergranular quartz within the unbroken alaskitic fabric, filled the small fissures, and 

collecting in larger masses formed itself on a small scale an independent intrusive in 

nearly the same sense as the alaskitic magma had done. We may logically conclude -------~--~-------. 

a Professional Paper U.S. Geol. Survey No. 42, p. 232. 
108 ORE DEPOSITo OF SILVER PEAK QUADRANGLE, NEVADA. 

that this quartz left upon consolidation a residue, which was still thinner and more 

aqueous, which had its part in the metamorphism of the country rocks, and whose 

minemlizing effect~ will be noticed later on. 

NATURE OF INTRUDED ROCK. 

The rock into which tho siliceous magma was injected is a comparatively thicK 

series of thin-bedded, shaly, and calcareous sediments intercalated w1th beds of pure 

limestone, now metamorphosed into marble. The thin-bedded sediments ~re sometimes carbonaceous, sometimes streaked with sandy material. (Pl. XXI, B.) 

Near the siliceous intrusions the strata are often saturated with siliceous material in seams, lenses, and nodules, and are also altered throughout their whole mass 

chiefly by silicification. Locally the alteration has produced mica schist and occasionally the microscope shows the presence of green hornblende and epidote, as well 

as quartz and feldspar, in the altered rock. The intrusions of quartz-feldspar material or of quartz alone are sometimes interlaminated in the schists like the leaves of a 

book, making a kind of gneiss. In some cases, as near the Crescent, this alteration 

of the intruded strata may extend only a few feet away from the zone of intrusive 

lenses of quartz and alaskite, showing its dependence upon this intrusion. 

The altered country rock contains gold in small quantities, as shown by assays, 

chiefly those taken in the Hickey tunnel (p. 50). This gold was probably introduced 

along with other materials during the process of metamorphism. 

FOLDING AND FAULTING. 

The limestone-slates are contorted on a minor scale. Most of this crumpling was 

probably due to the intrusion, for the parallelism of the bedding to the lenses shows 

that not only the granitic alaskite but the alaskite-quartz and even the quartz lenses 

have pushed aside the schist to make room for themselves. There is, very little folding on anything but a microscopic scale. Faulting on a small scale was observed in 

outcropping rocks, but no important faults were detected. 

CRUSHING. 

All the rocks-limestone, slate, alaskite, quartz, and altered diorite or greenstone-are locally more or less crushed, though much of the rock is intact. The 

crushing varies from a mere straining to complete granulation. There has been 

practically no crystallization or metamorphism subsequent to the crushing. Sometimes a very little sericite has been developed along the crushed cracks. In one 

thin section of alaskite from the Crescent, where there had been crushing subse-

' quent to the final consolidation, it was observed that along cracks the crushed 

orthoclase and microcline were being altered to albite, but not to any great extent. 

Universally otherwise the crushed feldspars of the alaskite remain perfectly fresh. 

In the Frank No. 2 it has been noted that some of the alasktte is crushed aml some 

uncrushed, the difference appearing to be due to the slightly different age of the 

alaskites. In this case the diorite or greenstone is also uncr'ushed. In other instances 

the greenstone has escaped most of the crushing, while all of the alaskite has been 

subjected to it. In some crushed alaskite and quartz it has been found that the 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 55 Pl. XX I 

PAYMASTER MINE, LONE MOUNTAIN DISTRICT. 

H. COR<lUGATED, THIN-BEDDED LIMESTONE IN CANYON IN MINERAL RIDGE, 1 MILE NORTH OF SILVER PEAK. 
DRINKWATER TYPE OF GOLD MINES. 109 ) 

pyrite has also been affected, showing that it was formed previous to ~:p.~ stress; in 

other mines uncrushed pyrite occurs in rock which has been crushed, and it is therefore subsequent to the stres:;;. 

From these observations the conclusion is drawn that the chief crushing was 

attendant upon the crystallization of the alaskite and quart.z, w:as in general J:revious 

to but partly contemporaneous with the diorite intrusion, and was previous to the 

deposition of the subsequent ores. 

FORM OF ORE DEPOSITS. 

The ore deposits are lenses of various dimensions, as s'een both on horizontal and 

vertical planes. These lenses are most abundant along certain zones in the intruded 

formation and overlap one on another. They 

disappear by wedging or by forking and splitting into two or more branches. Thus a series 

of quartz stringers may unite horizontally or 

vertically to form a massive lens. 

These lenses are original and are not fragments of larger dike-like bodies which have 

attained their form as a consequence of shearing. The wedging out of the lenses is not 

attended by evidence of unusual movement. 

Moreover, the phenomena of splitting and uniting (fig. 39), which are observed quite as frequently as the simple wedging, forbids the 

assumption that the form is not primary. 

CONCENTRATION OF GOLD. 

The assays given in the description of the 

Drinkwater mines show an unusual quantity 

of disseminated gold in thll alaskites·and to a 

0 10 

FIG. 39.- Rough horizontal section of portion of 

quartz lens exposed in lower stopes of the Drinkwater tunnel, showing forking of lens. 

certain extent in the schists which they have intruded and which have been metamorphosed at the time of the intrusion. Therefore it is probable that this alaskitic 

magma contained more gold than the ordinary magma. Moreover, the quartz lenses 

contain throughout much more gold than do the alaskite lenses, and the values in this 

quartz usually decrease with incoming feldspar, although there are cases where this 

rule is not observed (see p. 50). It seems, therefore, that the more siliceous the 

magma became the more marked became the presence of gold. Thus the magma 

was capable of holding the gold dissolved and of separating it, along with the silica 

and other alaskitic elements, from the less siliceous and earlier crystallized granites. 

A relatively large proportion of gold tended to remain in solution in company with the 

excess of free silica, and a large part of this was deposited when this exces.s of free 

silica crystallized in the form of magmatic quartz, whether in the interstices of the 

alaskite, m small cracks, or in the lenticular bodies into which the silica also collected. 

Besides the chemical fitness of the siliceous magma to contain gold in solution, 

other properties of the last-crystallized quartz must have been more favorable to 
110 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

local concentrations than in the case of the portions of the magma which crystallized 

earlier. Many observations have been recorded in various parts of the world which 

indicate that a granitic magma tends to grow more aqueous and less viscous as it 

becomes more siliceous. Some reasons for believing that the alaskite was less 

viscous than normal granitic magmas will be indicated farther on. In accordance 

with this idea the quartz which was the last to consolidate should have been less 

viscous than the alaskite. This would have allowed a greater mobility of materials 

and a greater range of currents, permitting the accretion of certain materials and 

allowing the gold to increase in favorable localities to commercial quantities. 

SUBSEQUENT MINERALIZATION. 

In the chief mines of the district, those of the Drinkwater group, the formation 

of ore minerals subsequent to the primary consolidation of the quartz lenses has taken 

place on an unimportant scale. None of the ores now in sight are even partially of 

this character. Occasionally, however, some later precipitation has taken place. 

In the Hickey tunnel beneath a decomposed greenstone dike which had been intruded 

along the hanging wall of a quartz lens the quartz was cracked for a foot or more from 

the contact, and in these cracks pyrite had formed, derived in large part from the 

diorite. Along this zone the ore is sometimes richer than in the unaltered quartz 

below, sometimes poorer. The richer ore has a gangue of quartz with some calcite 

and chlorite and carries pyrite and galena. The calcite, like the pyrite, is probably 

derived from the greenstone. 

Farther east on the same zone, in the Western Soldier and Homestake, all the 

mineralization that was observed was primary. In the Mary, however, the occurence of subsequent mineralization is clear and the primary and subsequent ores occur 

together. In the primary ore lenses the gold is mostly in a free state and is said to 

average $12 or $15 to the ton. These lenses have been cracked by subsequent movement and the cracks, especially those near the hanging wall, have been filled with 

pyrite and galena of the same nature as the sulphides in the primary quartz but more 

abundant. In this subsequent ore, or, rather, ore which has been affected by both 

primary and subsequent mineralization, values of $26 to $84 are reported. Throughout the mine the hanging-wall portions of the lenses are richer than the rest, a fact 

which suggests ascending solutions as the cause of the subsequent mineralization. 

In the Last Chance, on the same zone, besides the ordinary primary ore there is 

an undoubtedly subsequent band of galena and altered pyrite, a fraction of an inch 

thick, on the contact of a greenstone dike with a quartz lens. This band shows good 

gold values. 

In the Frank No.2 fragments of the auriferous quartz lens included in intrusive 

greenstone seem to be richer than the average. This ore shows galena and pyrite in 

parallel cracks in the quartz. These sulphides are undoubtedly therefore subsequent. They are associated with some eontemporaneous calcite which, as in the 

case of the Drinkwater mines, is probably derived from the greenstone. The values 

here are also high in gold. 

From the above data the conelusion is reached that subsequent to the first or 

primary deposition of minerals and subsequent to the intrusion of the diorite, 

minerals were again deposited along cracks in the original quartz. These minerals 
DRINKWATER 'l'Y PE OF GOLD MINES. 111 

are the same as those first deposited, and on this account they might be thought to 

be due to secondary concentration, the material being derived from the minerals 

first formed and simply concentrated by subsequent circulating waters. This perhaps has sometimes been the case, but in the ch1ef example, that of the Mary mine, 

the amount of the subsequent deposition is so large as to suggest a fresh and independent supply of material. This conclusion is arrived at also by the aid afforded 

by the consideration of the Great Gulch mine, where the subsequent mineralization 

is undoubtedly an independent process. The phenomena in the Mary mine indicate 

the work of ascending waters, and if the conclusion which the writer believes to be 

most probable is accepted-that the subsequent deposition brought new material not 

derived from the first-then these new solutions must have had a composition like 

those from which the primary ore was deposited, although, judging from their effects, 

they were more attenuated and more like ordinary vein solutions. In this case we 

may adopt the explanation which has been arrived at in the case of the Great Gulch 

mine to account for the fact that the primary and subsequent mineralization followed the same channel, namely, that the primary quartz is the most brittle rock of 

the terrane and when subjected to stress would crack and offer channels for circulating solutions wp.ich the surrounding schists and even the tougher and less homogeneous alaskite would not afford. 

RELATIONS OF THE GREENSTONE OR ALTERED DIORITE. 

Dikes of diorite of no great size are frequent but not abundant near the mines 

and prospects, and often border quartz lenses or split them. As already stated, the 

distribution of these dikes in relation to the main granitic intrusions are such as to 

suggest that they may be genetically connected with this general intrusion and form 

one of the latest phases of it. The intrusion of the dikes preceded the subsequent 

mineralization. The conclusions above arrived at as to the nature of this mineralization favor the hypothesis that the mineralizing solutions were an after product of the 

grantitic intrusion, representing a later stage than the quartz lenses. If this is true, 

as will be more strongly indicated later on, the age of the diorite is fixed as subsequent to the intrusive quartz magma, which in part constitutes an or~, and antecedent to most of the work accomplished by the later and thinner granitic solutions, 

whose activity was probably of considerable duration. 

A striking circumstanee, affording a elue which can not be negleeted, is that the 

greenstone which accompanies the quartz and alaskite lenses is always deeomposed, 

while the earlier alaskite whieh it cuts is fresh, with largely unaltered feldspars. If 

any doubt should arise after the previous deseriptions as to the primary age of the 

fresh feldspar, this is set at rest by the faet of its having been crushed and granulated in many cases by earth movements, which frequently have not affected the 

adjacent diorite nearly to such a degree. Therefore there is only one explanation of 

the circumstance above noted, namely, that subsequent to the diorite intrusion solutions have circulated through the rocks which were similar in chemical composition 

to the alaskite and so have not attacked the alkaline feldspars, but were different in 

composition from the diorite and so attacked and decomposed the soda-lime feldspars 

as well as the other dioritic constituents. Such alkaline solutions must have been 

very aqueous, for in many cases they have left no trace other than the decomposition 
112 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

of the diorite. In some cases,Jh~wever, the subsequent mineralization also occm:s~ 

suggesting that the decompositi.on and the mineral precipitation were d~e to the 

same solutions. One is also naturally led to consider that the chemical similarity of 

these later solutions to the alaskite and to the solutions. which deposited the primary 

ores is not accidental, but results from intimate relationship, and to postulate that 

such later solutions were residual from the last crystallization of the alaskite and 

quartz magmas, and that the activity of these solutions endured throughout and 

subsequent to the dioritic intrusions. The interesting fact above noted, of the 

alteration of potash feldspar to albite along a crack subsequent to the crystallization, indicates that at least some of the circulating solutions carried sodium in excess 

of potash. 

The close association of the greenstone with the quartz and alaskite, and frequently with the subsequent ores, easily leads one to the hypothesis that this subsequent mineralization was dependent upon the diorite; but most of the diorite dikes 

have no later ores in their vicinity, and in the mine where the largest deposit of subsequent ore was noted there is no diorite, so that the two phenomena have evidently 

no very intimate relation. Both are probably manifestations of a common activity, 

both have probably been brought i11to the quartz zones because the easy fracturing 

of these afforded the most inviting channels, and the intrusion of the diorite in its 

turn has locally brought about fraetures in the brittle quartz which have served as 

channels ' for the subsequent solutions. 

GENERAL CONCLUSIONS. 

The general conclusion is that in this district a series of thin-bedded, fissile, shaly 

limestones have been intruded by a highly siliceous alkaline magma. The magma 

was a viscous fluid, less viscous than a normal granitic magma, but still capable of the 

role of intrusion. From this magma crystallized, besides some of the ordinary accessory granitic minerals, principally feldspar and quartz, the consolidation of the feldspar in general p:r:eceding that of the quartz. The proof that the magma penetrated 

the sedimentary rock mass in every pore, and that many of the larger intrusive lenses 

are of accumulated material which was intruded along small channels now often difficult to find, together with the relatively slight amount of fracturing to which the older 

crystals have been subjected, indicates that the crystallization was all accomplished 

subsequent to the injection. It was, however, slow, so that the residual viscous 

quartz, before its final consolidation, was in part drawn off into large and small reservoirs and so could play the role of an independent intrusion. A process of magmatic 

differentiation by partial crystallization is here proved. 

When the alaskite magma was partially crystallized, the residual portion, previous to the consolidation of the material occupying the interspaces, altered the earlier 

formed feldspar more or less to musc'ovite, undoubtedly through the action of contained fluorine. It has long been known that orthoclase may be altered to muscovite 

(often sericitic) and quartz, especially near ordinary mineral veins, where the action 

has been ascribed to mineralizing waters, probably containing fluorine a. The same 

alteration is strikingly shown near tin veins, where it has been regarded as due to the 

a Spurr, J. E., Prof. Paper U.S. Geol. Survey No. 42, p. 231. 
DRINKWATER TYPE OF GOLD MINES. 113 

vapors accompanying the mineralization, and these vapors have usually been held to 

be the after product of a granitic magma, and to represent in part the final stage of 

eruptive activity. As noted previously, also, fluorine has been found necessary for 

the artificial production of mica. That the formation of muscovite wherever it 

occurs, even in granite, has been due to the action of mineralizers such as fluorine, is 

therefore a well-grounded theory. This, however, the writer believes is the first case 

where it has been shown by microscopic study that muscovite has universally 

developed as the result of the alteration of already formed feldspar by the action of a 

residual, probably fluorine-hearing, magma, a residual magma which afterwards 

crystallized out as feldspar and quartz, with occasionally some contemporaneous priInary muscovite. 

The chemical composition of muscovite is similar to that of potash feldspar, so 

that the feldspar is easily decomposed by the effect of the proper reagents to muscovite, together with some quartz. The possibility of the origin of the muscovite in 

granite, and perhaps the quartz also, by the alteration of amorphous feldspar, was 

suggested as early as 1864 by Bischofa. He wrote: 

The mica, which occurs in its own crystal form in granite, may possibly have originated from an elementary 

amorphous feldspar mass. In this case the separated silicic acid may have been entirPly removed in tho alkaline silicates or a part may have remaine<l as quartz. In thp, lattPr case the quartz in granite would have the 

same origin. 

That the alaskite lenses are the fillings of cavities which were already present in 

the schist is out of the question. The parallelism of the schistosity, with the curving 

walls of the lenses, shows that the intrusion occupied spaces which it itself created. 

It is probable, moreover, that before the process of consolidation began the magma 

had entirely filled the reservoirs which consolidated as lenses, for the relatively homogeneous texture of the alaskite is as striking as it is in regular zonal dikes and is 

against any idea of gradual accretion during consolidation. As the form of the alaskite lenses is identical with that of the quartz, and as there are all transitions in composition between the two rocks, the same is probably true, though perhaps less strikingly, of the quartz bodies. The lenticular form of these masses (including the ore 

bodies) is like that of pegmatite dikes and pegmatitic quartz veins which have been 

observed in many other places, in schists near intrusive granite contacts. This form 

is believed by the writer to be the normal one for attenuated, aqueous, but still viscous granitic material, injected into schists from granitic masses. Attenuation is 

indicated by the fact that the lenses are typically isolated, the entrance canals often 

not being visible; that the material, however, was relatively viscous and had considerable body is shown by the fact that instead of losing itself in the schists it has forced 

them open so that they bend conformable to its boundaries. More aqueous solutions 

would have simply penetrated the schists, and impregnated and replaced them along 

openings such as schistosity planes or fractures. Moreover, the largest feldspars, 

even where the rock is coarsest and most pegmatitic, reach only a few inches in diameter, and are not comparable to the giant crystals found in some pegmatites. This 

fact is taken to indicate a viscosity and a relative lack of mobility in the fluid. The 

fact that the same characterizations apply as a rule to both the alaskite lenses and the 

a Chern. und phys. Geologie, vol. 2, p. 744. 

13002-No. 55-06-8 
114 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

quartz lenses indicates that the alaskitic fluid must have been much the same as that 

of the quartz, both being less viscous than that which has formed the true granites, 

which neither in this quadrangle nor in similar provinces is accustomed to form lenticular intrusions, but which occurs in bold and well-defined dikes and sheets of which 

all the connections are easily traceable. Yet the alaskite here is transitional to granite, showing that the variation of viscosity as well as composition was gradual, with 

no critical point of change, and that the mobility increases with the increasing siliceousness of the magma. The alaskite magma must have been aqueous, and the proportion of water must have sometimes been considerable. This is indicated by the 

numerous cracks which formed in the alaskite, which were filled by the residual quartz 

'and which can best be explained as contraction cracks, due to loss of volume on consolidation (Pl. XIII, A). 

The intruded limestone slates, however, were often thoroughly saturated with 

siliceous and often feldspathic material. This indicates material allied to that which 

has filled the lenses, but of greater attenuation and penetrating ability. It is regarded 

as material residual from the solidification of the quartz and alaskite lenses. 

After the last crystallization of the intrusive alaskite and quartz, diorite dikes 

were injected, and probably directly afterward (for a direct connection with the granitic intrusion is probable) relatively thin aqueous solutions circulated along cracks 

and produced a subsequent mineralization, not approaching, however, in commercial 

importance in this especial district the primary mineralization. The brittle quartz of 

the lenses, having been cracked, offered the best channels, and here the subsequent 

mineralization took place, generally under the relatively impervious schist hanging 

walls, indicating ascending waters. In the case of the Mary mine the results do not 

resemble so much a rearrangement of old material as a new deposition, for the new 

material differs in containing a greater proportion of sulphides to free gold, indicating 

a greater amount of sulphur in the solutions; yet the materials deposited-pyrite, 

galena, gold, etc.·~are identical in nature to those of the first mineralization, and a 

later stage of the first process is suggested. This hypothesis is ou.ly formed and 

strengthened in the writer's mind by the consideration of other subsequent ore 

deposits, to be described later, whose significance is clearer. 

For various reasons it is believed that this later aqueous residue of the granitic 

eruptions was highly alkaline and that in some cases sodium preponderated over 

potassium. 

The quartz and feldspars which have crystallized from the alaskite and quartz 

magma are crowded with fluid inclusions. 

In general the inclusions in granitic quartz are held to represent imprisoned portions of the liquid residual from total crystallization. In cases where the nature of 

these inclusions has been chemically investigated (in other regions) it is found to be 

largely pure water. In other cases considerable amounts of potassium chloride, 

sodium chloride, sulphates of potash, soda, and lime and also free acids were present. 

Sorby obtained from the powder of a piece of quartz so much alkaline chlorides 

and sulphates that he estimated the content of such salts in fluid inclusions to be at 

least 15 per cent. a Carbonic acid is present in many of these inclusions. In other 

a Quart. Jour. Geo!. Soc., 1858, p. 472. Cited by Zirkel, Lehrbucl:i 'der·Petrograpbie, 2d ed., vol. 1, p. 171. 
DRINKWATER TYPE 01!' GOLD MINES. 115 

microscopic fluid inclusions cube-shaped crystals have separated out which have been 

recognizee as sodium chloride. ZirkeJa notes the presence of such tiny cubes in the 

quartz of a syenite granite porphyry from Nevada, whose exact locality, however, is 

not indicated. 

If the investigation of fluid inclusions in quartz offers one clue to the chemical 

nature of the solutions which represent the final residue of granitic consolidation, 

valuable clues are also offered by the investigation of the nature of minerals which 

are deposited in the last stages of this process. An observation by Doctor Lehmann 

is applicable in this connection. b According to him in the region of Saxony which he 

studied, the orthoclase of the pegmatite dikes is usually intergrown with albite in the 

form of perthite. Albite also covers the orthoclase in thick plates. In these cases 

it is quite evident that so long as the orthoclase substance was being separated out 

the albite, as well as the quartz, remained chiefly in solution and only separated 

in independent crystals toward \the end of the orthoclase formation. The large 

orthoclase crystals appear to be etched as if they had afforded material for the 

formation of the free albite through a ptutial leaching out of the microscopically 

small interlaminated albite lamellre. .:'{evertheless, the albite can not in every case 

owe its existence to this leaching, and Doctor Lehmann concludes that from the 

mineral solution only a little albite was precipitated at the same time as the orthoclase, but when the orthoclase substance was exhausted more and more albite was 

precipitated. c 

The one case in the Crescent property cited above (p. 108) of the formation of 

albite at the expense of potash feldspar subsequent to the crystallization of the 

alaskite seems to fall in line with Doctor Lehmann's observations. 

The order of events was then as follows: 

1. Intrusion of a thin siliceous magma into calcareous and shaly sediments. 

2. Consolidation of granitic portions. l 

3. Consolidation of alaskitic portions. w· h L d h' 

C I'd t' f t t' I It atuen ant crus mg. 4. onso 1 a Ion o quar zose por wns. 

5. Diorite intrusion. 

6. Circulation of solutions residual from consolidation of No. 4, alteration of 

diorite to greenstone, and deposition of subsequent ores. 

~os. 2, 3, 4, and 6 are regarded as really a single process whose different stages, 

as indicated, have no natural boundaries, but overlap and interlock. No. S is an 

interruption of the process in the shape of an invasion of a different magma. Yet 

this interruption can not safely be regarded as accidental and foreign to the 

natural order of events. The diorite, as already noted, is probably a phase of the 

granitic intrusion, and the presence of altered diorite or greenstone is striking in 

many gold fields of the world, especially those which have been suggested or shown 

to be primarily dependent upon granitic intrusions. Concerning some of them, 

indeed, there are published reports in which the origin of the gold is referred to the --~--~-~ - ~~· -----

a Zirkel, Lehrbuch der Petrographic, 2d ed., Yo!. 1, pp. 171 and 172. 

b Lehmann, Dr. J., Die Enstehung der Altkrysta!linschen Schiefergcsteine. Bonn, 1884, p. 48. 

c This observation is cited and supported by W. C. Brugger (Die Mineralien der Syenit-pegmatitgange, Zeitsch. fiir Kryst., 

1890, p.154). Bragger (op. cit., pp. 167, 1G8) concludes that some albite forms in the pegmatitic dike-veins at a later period 

than the potash-feldspars, being one of the products of the second period of consolidation, when the chief factor in mineral 

formation is the influence of the ''mineralizers" residual from the previously consolidated portion of the magn:a. In part 

this later albite has originated hy replacement of earlier orthoclase, showing that the residual solutions had grown sodic. 
PLATE XXII. 

THIN SECTION SHOWING GENESIS OF MAGMATIC QUARTZ VEIN IN ALASJtiTE. 

Drawing of vein-like portion of thin section 254 (alaskite from the Magpie prospect ''"indypah district), showing 

the genesis of a magmatic quartz vein. Areas of feldspar (dark) are drawn as a whole to distin!!uish them 

from the quartz areas (light). Each of these areas, however, is in detail a mass of interlocking crystals. 

The quartz of the veinlet is of the same age and character as the intergranular quartz between the feld-

'-pars. The feldspar is chiefly orthoelase and albite. Note the typically idiomorphic outlinee of the 

feldspar against the quartz, both in the veinlet and the intergranular quartz. The feldspar is the earlier 

crystallization, and masses of idiomorphic crystals floated in the magma almost filling it. The residual 

magma crystallized as quartz, completing the solidification of the rock. The mass of earlier feldspar 

crystals was often solid enough to be split, and in the crack thu' formed the later quartz took on an elongated form a:1.:! became a vein. Enlarged about 38 diameters. 

116 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 55 PL. XXII 

THIN SECTION SHOWING GENESIS OF MAGMATIC QUARTZ VEIN IN 

ALAS KITE, 
DRINKWATER TYPE OF GOLD MINES. 117 

greenstone on account of the close relation of the two, while the general existence of 

the same gold fields has been maintained by other writers to depend upon granitic 

intrusions. This, for example, is the case in some of the Australian gold fields. In 

many such cases the greenstone and the auriferous quartz may perhaps be, as they are 

at Silver Peak, separate manifestations of a general great process and otherwise not 

intimately related. It is easy to mistake the close association as indicating the 

simple dependence of one upon the other. For instance, the ores at Silver Peak 

have been sometimes explained by visiting engineers as dependent upon the 

greenstone. 

ANALOGOUS CASES ELSEWHERE IN THE QUADRANGLE. 

THE DIVIDE~]) GROUP OF PROSPECTS IN THE WI~DYPAH DISTRICT. 

These prospects lie within a zone of alaskito some 150 yards wide, which itself 

lies in the center of an area of granitic rock and is intrusive into it. The alaskite is 

fine and even grained, containing quartz and feldspar in equal proportions, the feldspar being both orthoclase and albite. The rock contains original pyrite largely 

altered to limonite and hematite, with a little magnetite and original hematite. 

There is occasional biotite and a little sphene and zircon. In some cases the feldspar 

is largely altered to sericite and sometimes is entirely decomposed. As a rule the 

feldspar has idiomorphic to hypidiomorphic outlines, and the quartz occupies the 

spaces between the feldspar crystals, which it also sometimes invades along cracks. 

The microscope shows that some portions of the alaskite have much more quartz 

than others, and by a complete 1vithdrawal of the feldspar typical granular contemporaneous quartz results, usually in parallel streaks. (Pl. XXII.) Microscopically, 

the alaskite contains small bur1ehes and veinlets of such segregated quartz. These 

bunches have an irregular and indefinite distribution and are sometimes mixed with 

coarse feldspar, indicating their contemporaneous origin. 

The quartz, as well as the alaskite, incloses some pyrite, which generally c;ntains some gold. Perfectly fresh alaskite has been claimed to be second-class ore, 

but the assay of one spe'3imen showed only traces of gold and silver. Similar alaskite with the feldspar entirely decomposed to sericite is claimed to be first-class ore. 

In specimens of this free gold is visible. Most of the ore, however, has been sought 

in the quartz lenses or ne:>cr them in the alaskite. 

GENETIC HELATIONS OF THE GREAT GULCH ORES. 

At the Great Gukh mine the general geology is like that of most of the typical 

gold mines of the Drinkwater type. The country rock is a thin-bedded limestone 

slate, considerably altered and schistose. Alaskite occurs in interbedded lenses in 

the schist, occasionally in cross-cutting bodies. Lenses of white vitreous quartz are 

also frequent. These often become feldspathic and pass into alaskite. 

The ore is arsenopyrite, which occurs in streaks of all thicknesses up to 1 or 2 

feet, but usually much less. These streaks are of irregular size, contracting to small 

seams and expanding to lenticular masses. The larger bodies are noticeably associ.:. 

ated with alaskite and quartz lenses, especially with the quartz. In these lenses the 
118 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

ore occurs sometimes as cross-cutting streaks, but usually as bands parallel to the 

walls of the lenses and the bedding of the schists. The hanging wall of quartz lenses 

is an exceptionally favorable locality. In part the ore has originated by replacement 

of limestone schist and alaskite. 

The association of the ores with the silicio}lS injections is plainly due to the fact 

that these, being more rigid, have yielded better openings than the slaty country rock, 

when stress was applied subsequent to their intrusion. These cleaner and more 

definite cracks were naturally the channels for mineralizing solutions. The localization of the gold near the hanging wall of a fractured quartz lens beneath the relatively 

impervious schist indicates that th3 solutions were ascending. 

The general conclusion is that fracturing occurred subsequent to the intrusion of 

the primary alaskite and quartz. Alcng the channels formed at this time the ascending waters rose, carrying sulphur, iron, arsenic, and gold, which they deposited. 

The period of this mineralization is uncertain from the local data, but the resemblance 

of the phenomena here to those of the subsequent mineralization in the Mary mine 

is important. The Groat Gulch mine offers a more striking and unequivocal case of 

subsequ(mt independent mineralization, and in default of evidence to the contrary 

we may couple the mineralization in the t\vo mines together. 

Gl'JNETIC RELATIONS OF THE SIT,Yl£H J\UNES 01'' ::\IINJ£RAL RIDGE. 

CHARACTERISTICS OF THE POCATELLO GROUP. 

Aside from the mineralization, the general geology at the Pocatello and Vanderbilt mines is like that of the Great Gulch mine. The country rock is a schist, which 

represents a shaly limestone, now more or less altered, with the development of 

isolated crystals of microcline, orthoclase, oligoclase-albite, quartz, etc. This is 

very ncar the top of the limestone-schist formation, which is overlain by massive 

brown dolomite. In the schist arc alaskite lenses· associated with quartz lenses, both 

having the same characteristics as at the typical gold mines. The ore zone runs 

along a zone of these quartz lenses. Greenstone dikes and sheets are present, following especially the zone of quartz lenses; they are in general parallel to the quartz, 

but sometimes cut across. As is the case in the gold mines, the diorite is entirely 

altered to secondary materials. Near the greenstone the quartz is frequently 

cracked, broken, and mineralized. Assay shows this portion to be richer than the 

ordinary white quartz in both gold and silver. 

The ore on the whole is altogether subsequent to the quartz, in which it occurs· 

along cracks. The most characteristic mineral is the mixed sulphide and oxide, containing copper, antimony, silver, and gold, described on page 91. The values in the 

ore arc said to have been principally silver, though some assays showed much more 

value in gold than silver, and a comparison with portions of the quartz which do 

not contain subsequent ore shows that both the gold and silver in this case are principally of subsequent origin. 

The conclusion arrived at is that the schists were first injected by a silicious 

magma, which crystallized as alaskite and quartz. Basic dikes were subsequently 

injected, which followed along the zone of quartz and alaskite lenses, because here 

fracturing was more easy on account of the greater brittleness of the materials. The 

• 
GENETIC RELATIONS OF SILVER MINES OF MINER.AL RIDGE. 119 

intrusion of the diorite produced considerable fracturing. Along these fractures 

circulating mineral solutions deposited gold, copper, and silver, and these were very 

likely the solutions which altered the diorite to greenstone. The whole history indicated is analogous to that of those mines in the Drinkwater group, which show noticeable subsequent mineralization, although the character of the ore is somewhat 

different in that more silver and copper in proportion to gold arc present. 

CHARACTERISTICS OF THE BLACK WARRIOR GROUP. 

The prospects of the Black Warrior group are in the dolomitic marble which 

overlies the schist formation, and an~ not far from the schist boundaries. The ores 

are veins or bands of quartz or jasperoid running parallel to the bedding planes and 

occasionally cross cutting the formation. They arc irregular in form and arc evidently due mainly to replacement. Microscopical study shows that the quartz as a 

rule has a jasperoidal retiform texture, unlike that of the granular quartz previously 

described. In the quartz the black stetcfeldtite-like copper-silver-antimony mineral, 

and some galena, are disseminated, and are plainly prin:ary and contemporaneous 

with the gangue. These veins are believed to be the result of waters which have 

obtained access along fractures and have spread out along convenient stratification 

planes. Greenstone dikes of the same character as those previously described are 

intrusive into the dolomite, chiefly in interbedded sheets, and arc often n<~ar the vein. 

These dikes sometimes occur on the foot or hanging wall of the ore or both. The 

relative age of the greenstone and ore is doubtful. 

COMMON CHARACTERISTICS OF POCATELLO AND BLACK WARRIOR GROUPS. 

In both the Black Warrior and Pocatello groups of ore deposits the ores are 

similar in nature, being characterized principally by the black stetefeldtite-like 

mineral. Both are accompanied by greenstone. The chief difference is that one is 

in the dolomite near the schist formation, while the other is in the schist near the 

dolomite, also that in one case the inclosing quartz is contemporaneous with the 

metallic minerals and in the other is antecedent to them. 

The similarity of the ores. suggests that both are due to the same mineralization. 

In the Pocatello group, where the channels of mineralizing waters were in older 

quartz, any silicifying potentiality which the waters may have had would be obscured 

while in the dolomite of the Black Warrior group it!' effects would be plain. In the 

latter case the solutions are shown to have been silicious. The decomposed state of 

the greenstone in both groups suggests the same concLusion that was reached in the 

case of the gold mines only-that the mineralizing solutions were alkaline. 

This mineralization seems to differ from the subsequent mineralization, described 

in the case of the Great Gulch, Mary, and other gold mines and prospects, in the 

presence of more silver and copper, although otherwise the facts are not unfavorable 

for regarding all as belonging to the same period. The writer desires to put forth 

here as a plain hypothesis an idea which has been arrived at by considering and 

reasoning from the distribution and character of ore deposits throughout the quadrangle. This hypothesis is that in the granite, or in rocks silicified by the meta-
120 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

morphic effect of the granite, solutions of granitic origin have deposited gold predominantly, and that in the calcareous or dolomitic intruded rocks more silver and 

copper were precipitated from the same solutions, the difference being due to the 

selective precipitative influence of the wall rocks. 

GENETIC R~:;LATIONS OF THE LONE 1\IOUNTAIN GROUP OF 1\HNES. 

The Lone Mountain group of mines, as described in this report, are all situated 

in Paleozoic stratified rocks. These rocks are limestones, dolomites, and shales, 

which have been more or less metamorphosed by the intrusion of granitic masses. 

The metamorphism is most intense near the contact and fades away gradually as 

the distance from it increases. The limestones and dolomites are changed to marble, 

the shales to hornstones and schists, with the development of typical metamorphic 

minerals. 

The few specimens of intrusive granite and alaskite examined show characteristics similar to those of some of the phases studied from Mineral Ridge. Alaskite 

from near the prospects at Weepah is similar to a very common type near the Drinkwater mines. A specimen of the Lone Mountain granite is like the granitic phase of 

alaskite in the Mary mine. In this Lone Mountain type, as well as in the Mineral 

Ridge granite, two generations of crystals are indicated by microscopic study, and 

some magmatic alteration of feldspar to muscovite, between the first and second 

crystallizations, is evident. 

The veins of the Lone "Mountain group characteristically follow the stratification of the sedimentary rocks. Where they thus occur along bedding planes, these 

planes have evidently been the sites of differential movement, which has produced 

crushing and greater openness. More rarely the veins are found in crosscutting 

shear or fault zones. 

Along the vein zones, whether parallel or transverse to the stratification, the 

vein material, consisting chiefly of quartz, occurs rather irregularly in separated 

veinlets or in lenses and pockets of considerable size. Some of the veins are apparently filled deposits, while others, especitdly those in limestone or dolomite, are due 

to replacement. 

In the ores of the Paymaster-Esperanza type, the black stetefeldtite-like mineral 

occurs, together with galena and pyrite. Copper, silver, and gold are present. In 

ores of the Enterprise type, magnetite, specular iron, pyrite, chalcopyrite, and galena, 

with gold and silver, are present. At Weepah the quartz contains a small amount 

of the stetefeldtite-like mineral, with galena and free gold and a little copper. At 

the Alpine mine the primary ore is galena, now largely altered to carbonate. There 

is also a little copper stain. In general, therefore, there is a strong likeness among 

the ores of this district. 

The chief gangue mineral of this group of veins is quartz, but there is usually 

some calcite. In the Enterprise group many other minerals are present, chiefly 

epidote and garnet. 

Diorite made up of feldspar and hornblende runs along a part of the Enterprise 

vein zone. It is partly altered to epidote, carbonates, etc. At the Alpine mine 

diorite sheets and some crosscutting dikes occur in the marble and occasionally in 
GE:NE'fiC RELATIONS OF LONE MOUNTAIN GROUP. 121 

the granite, but these do not seem to be associated with the ore and are regarded 

as probably of later origin. 

The deposits of metalliferous jasperoidal quartz at Weepah and Alpine are, as 

indicated by their location near the intrusive granite contact, plainly dependent 

upon the same general action that produced the metamorphism of the sediments in 

which they occur. The metals have been introduced by siliceous solutions which 

emanated from the consolidating granite. The Enterprise type of deposits, with its 

gangue of typical contact metamorphic minerals, is still more clearly contemporaneous with the contact metamorphism of the strata. Some of the deposits of the 

Esperanza group are as much as 5 miles from the contact of granite on the map, 

and the sediments in which they occur are only slightly metamorphosed, so that 

fossils have been found in them, yet their mode of occurrence and the nature of their 

materials show a close relationship to the others described. 

The general conclusion is that at the time of the intrusion of the granite siliceous solutions emanated from the hardening mass and penetrated the surrounding 

sediments, which were thus recrystallizeJ and metamorphosed. Such solutions 

circulated most vigorously along openings which had been formed by the granitic 

)ntrusion. Most of these openings lay along bedding planes; some along crosscutting shear zones. Within half a mile or a mile of the granite there is evidence that 

a considerable quantity of such solutions vigorously circulated along hvorable 

openings, but at a greater distance, as in the region of the Paymaster group, the solutions had evidently become scanty, since they deposited small and irregular quartz 

veins which only partially filled the channels. 

These cireulating granitic waters, producing metamorphism in the rocks and 

vein formation in the fractures, plainly brought in from the granite the quartz and 

the various metals of ~he veins. a Evidently the genesis of these deposits is similar 

to that of the Black Warrior group of Mineral Ridge. 

GENETIC RELATIONS OE' ORES IN THJ1~ SOUTHERN PART OF THE 

QUADRANGI~E. 

All of the described prospects in the southern part of the quadrangle are near 

intrusive bodies of granitic rock, with which they are plainly closely connected. 

The described prospects in the Dyer district are identical in type with the Paymaster vein, in the Lone Mountain region, in respect to gangue, ore, and wall rock. 

They are mostly bedding-plane deposits, consisting of irregular streaks of quartz 

following zones of crushing. Their values are chiefly in silver, and the principal 

metallic mineral is the stetefeldtite-like mineral previously described. The localization of these deposits near a small area of granitic rocks and their association with 

a small deposit of specular iron indicate that they are the effect of granitic solutions. 

In the Windypah distr:ct the type of deposit found in the Dividend prospects, 

already described, is due directly to siliceous magmatic segregation. Other quartz 

veins, of the Hector type, follow shear zones in granite. In these shear zones the 

amount of quartz is variable, and the supplies of solutions were evidently not copious. 

The quartz contains pyrite and gold, and the wall rocks are sericitized and in part ~--------------------~ ---- ---------

a Molybdenite has also been reported from the Lone Mountain district, but without satisfactory confirmation. (Eng. 

and Mining Jour., Oct. 31, 1903, p. 667). 
122 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

kaolinized. The resemblance of these veins in composition to the Dividend type 

of segregated veins leads to the belief that these are also due to siliceous residual 

solutions derived from the consolidation of granite, which have circulated along 

available channels in portions of the granite which had already consolidated. 

Another type of the Windypah veins (Chloride type) occurs in calcareous and 

argillaceous sediments near the contact of the granite. The gangue is chiefly quartz, 

the metallic minerals chiefly stetefeldtite, galena, copper pyrite, etc. The values 

are chiefly in silver, but there is some gold. These minerals follow fracture zones, 

especially along alaskite dikes. They have formed largely by replacement. The 

country rock consists of metamorphosed sediments containing typical contact metamorphic minerals, including a little tourmaline, a mineral which \Vas not noted in 

the contact metamorphic zone of the Lone Mountain district. , 

Altered diorite or greenstone dikes are sometin!es associated with the ore;;;, which 

are mostly subsequent to the dioritic intrusion, but no genetic connection between 

the two was observable. 

The MacNamara prospect, already described, in the Palmetto district, belongs 

to the Chloride type. Here again the vein is a typical crushed zone and contains 

irregular streaks of quartz carrying galena, chalcopyrite, and pyrite, the values being 

mostly in silver, with considerable gold and lead. The country rock is a typical 

contact-metamorphosed sediment containing, as in the vVindypah district, a slight 

amount of tourmaline. Diorite dikes are present, hut again have no genetic connection with the mineralization. That part of the Paymaster zone which lies in 

metamorphic sediments resembles the MacNamara and still more dosely the Enterprise zone of the Lone Mountain district, being characterized by typical contactmetamorphic minerals. The values here are in silver and gold. In the granite what 

appears to be the same zone has different properties, the deposits being of a type intermediate between the Dividend and Hector types of Windypah. The quartz veins 

are slightly subsequent to the alaskite, in which they sometimes occur, but have 

the appearance of having segregated out from the immediate vicinity. The metallic 

minerals are copper and iron pyrites, containing gold, and barite in one place occurs 

as gangue. The fact that along what seems to be the same great fracture zone the 

ores are of different characters in the granite and in the intruded sediments indicates a probable origin by the same solutions, and the different characters of the 

veins is assumed to be due to the influence of the wall rock. 

GENF}RAL CONCLUSIONS AS TO ORIGIN OF 1\IE'l'ALLTPEROL'"S ORES. 

The metalliferous ores of the quadrangle are intimately interrelated, and their 

origin has been traced to the consequences of one event, namely, the intrusion of 

granitic rocks into Paleozoic sediments in probably post-Jurassic time. This district is favorable for such determinations as have been made, since the granitic 

masses are small and the grouping of the ore deposits around them is therefore 

'relatively more evident here than in a region like the Sierra Nevada, where the 

masses of granite are vastly larger. 

The ore deposits may be divided into the two following chief groups: 

1. Bodies of auriferous quartz, which probably separated in gelatinous form 

from alaskite during the process of crystallization and are of the same age and nature 
GENERAL CONCLUSIONS AS TO ORIGIN OF ORES. 123 

as the intergranular quartz of grai,lite amd alaskite. In such quartz bodies gold is in 

places segregated in eommercial quantities. 

2. Quartz veins due to replacement or impregnation of erushed material along 

fracture zones by silieeous solutions more attenuated than those described above and 

probably residual from the crystallization of the magmatic quartz of the first type. 

These solutions were probably diluted in various degrees hy magmatic water. Such 

deposits were formed chiefly along movement zones following bedding planes in the 

intruded Paleozoic strata, also in crosscutting movement zones in the strata, and to 

a less degree in the granites. Trwy were formed contemporaneously with the recrystallization and contact metamorphism of the sedimentR under the influence of the 

granite intrusion. They are typical quartz veins in the pure carbonate rocks and in 

the granites, but in the argillacl'o<1R rocks the quartz is often intermixed in various 

degrees with metamorphic silicate minerals, such as garnet, epidote, etc. The 

metallic elements present are princiDally silver, gold, lead, arsenic, antimony, copper, 

and iron in various combinations. There is more gold in tho granite, more silver 

and lead in the intruded strata. In the granite the metallic mineral is mostly pyrite, 

sometimes arsenical. In the sedimentary strata the charaeteristic metallic minerals 

are the altered sulphide containing silver, copper, and antimony, which we may 

provisionally call stetefeldtitc, and galena. The differences in the character of the 

metallic minerals is believed to he chw to the difference in the wall rocks, which have 

precipitated certain things from solution. Aside from the quartz, tho nature of the 

gangue is also believed to be chiefly due to the nature of the walls. 

The solutions from which all the typf's of ore deposits were formed arc believed 

to have been highly siliceous and alkaline and to have contained mineralizers, such 

as fluorine and boron, in a limited amount. 

COJ\1P AHISON OE' SIL VBR PEAK DEPOSITS Wl'l'H OTHER ORES. 

Of the various types of deposits in the Silver Peak quadrangle the most striking 

and interesting is that of the Drinkwater and similar mines, where the ore bodies are 

lenses of magmatic quartz in the schiRt. The other types of deposits described may 

be easily paralleled in other provinces of the world. They are not so distinctive as 

the Drinkwater type. Ores of this type doubtless exist elsewhere, but since their. 

nature and origin have not been fully determined examples have not been described. 

The description of the Sultana mine in Algoma, western Ontario, given by Dr. A. P. 

Coleman,a is, however, suggestive: 

The great quartz lenses of the Sultana min<' arc found at the northwestern eclge of an oval boss mapped hy 

Lawson as Laurentian. The inclosing rock mapped as Keewatin is green, fine grained, and not distinctly 

schistose. The boss of Laurentian consists in its central part of coarse-grained gray granitP with phenocrysts 

of orthoclase half an inch wide. Going westward toward the edge of the hoss, the granite slowly becomes schistose, showing distinct p>1rallelisrn of structure, and the porphyritic feldspars are rolled out into imperfect augen 

or lens-shaped portions. At the water's edge near the Crown Reef the coarse gray gneiss passes rapidly into 

the fine-grained, dark gray gneiss of a very schistose character, and then into very fine-grained black micaschist with crumpled strips or lenses of quartz. * * * The large quartz lenses in which the mine is 

worked lie in the schistose edge of the boss, and contain many thin sheets or thicker bands of the dark schist. 

As one approaches the * * * edge of the boss * * * the signs of crushing and shearing grow 

intense. The quartz shows "mortar" structure, being crushed into fine particles in dosing larger fragments. ------------- --- ------··-----

a Sixth Rept. Ontario Bureau of Mines, Toronto, 1R97, p. 121. 
ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

The feldspar is broken and portions shifted asunder, calcite sometimes serving as cement. * * * At the 

very edge the quartz is rolled out into streaks of crushed particles, the feldspar largely changed into a mixture 

of sericite nnd brown mica, and calcite and sulphides appear in considerable quantities. At the extreme edge 

little is to be seen in thin sectiom but brown biotite in minute scales. * * * 

It may be imagined that the granite, while still somewhat plastic-i.e., not yet cooled to the point of ronsolidation-pusherl up through the Huronian rocks, more or l<>ss shattering them and dragging out its own 

margin into the present schistose form. Before the process was romplt'te the shearerl edge of the mass was 

solirl enough to allow the formation of great cavities between the layers of gneiss and mica-schist. Hem the 

fluids of the now solid but still hot granite could circulate, deposit,ing the auriferous quartz. 

Taking the different types of deposits in the Silver Peak quadrangle as a whole, 

a number of similar examples at once present themselves in this same region. 

Fifty miles northeast of the northeastern corner of the Silver Peak quadrangle 

is the Belmont mining district, at one time productive, hut long since inactive. 

Here the writer has made a brief study of an interesting dike rock and its associated 

phenomena, which include mineral-hearing veins a. The dike is one of the outlying 

offshoots from a large body of siliceous granite. It is nearly half a mile wide and 

cuts Silurian slates and limestones. Near the contact the slates and limestones have 

been transformed into jasperoidb by the introduction of silica; in part they have 

also been altered to micaceous schists, often containing disseminated small bunches 

of yellow and red metallic oxides. In this rock occur quartz veins which carry rich 

antimonial silver ores. 

The dike rock varies greatly in texture and composition. One specimen collected, 

classed as a siliceous muscovite-biotite granite, is remarkable for the irregular 

arrangement of its constituent minel'als, the quartz often segregating into bunches a 

quarter of an inch in diameter with all the characteristics of vein quartz. A coarsergraii:ed biotite-granite taken at some little distance from the other has the same 

peculiarity, and in this place the blotches of quartz, mosaics of intergrown grains, 

are from one-third of an inch to one-half an inch in diameter. But the rock of chief 

interest is one which looks like a micaceous quartzite, and indeed consists, essentially, 

of muscovite and quartz. Microscopic study reveals in it the presence of the feldspar 

albite and proves that the muscovite has largely been derived from the alteration of 

orthoclase. Yet the rock is fresh and hard and the change has not been effected by 

surface weathering. 

The process must be regarded as one of endomorphism and as connected and probably contemporaneous 

with the exomorphism indicated by the alteration of the siliceous limestone of the wall rocks to jasperoid and 

mica schist. In both the intrusive and the intruded rock the result of the metamorphism has been the same, 

producing quartz anrl muscovite at the expense of the orthoclase on the one hand and of the calcite and 

subordinate minPrals on the other. In the case of the wall rock the metamorphism, being apparently from its 

distribution dependent upon the intrusion, evidently took place after this intru;;ion, and was brought ~>bout by 

the solutions which accompanied the igneous rock or were residual from its solidification. Within the dike the 

similar alteration was probably contemporaneous with that in the country rock.a 

White quartz veins often several feet in width occur in the immediate vicinity 

of .this intrusive mass. For these the conclusion is reached thatThese quartz veins are probably contemporaneous with those already described as occurring in irregular 

form within the dike rock itself, as evidently representing the final product of the residual solution of the gena Am. Jour. Sci., vol.10, Nov., 1900, p. 355. 

b Spurr, J. E., Geology of Aspen district: Mon. U.S. Geol. Survey, vol. 31, 1898, p. 219. 
COMPARISON WITH OTHER ORES. 125 

era! magma. In these quartz veins a the metallic minerals (chiefly stetefeldtite, an argentiferous orf of antimony, with some lead, copper, and iron) are scattered in bunches or disseminated particles, rarely in banded 

form. * * * 

The metallic minerals bein~ from their habit plainly contemporaneous with the quartz veins which inclose 

them, it is evident that the deposition of these minerals, the formation of the quartz veins, the metamorphism 

of the country rock to jasperoid and muscovite schist, and the endomorphism of the muscovite granite to 

quartz-muscovite rock were contemporaneous occurrences, all brought about by the same agencies, which were 

the solutions representing the end product of the difTerentiation of the granitic intrusive rock. 

In the Toyabe Range are numerous ore deposits, of which the chief ones lie near 

Austin, about 65 miles north of Belmont. The writer quotes his own summary of 

the district,b based chiefly upon the reports of the Fortieth Parallel Survey: 

Formerly the ores of the Toyabe Range were of great economic importance, but with the decline of the 

mining induqtries of Nevada they have been almost forgotten. The principal mining region was in the neighborhood of Austin, but mines were found from here southward all along the range. Mr. Emmons has described 

many of the deposits, which in nearly every case consi."t of veins of white quartz carrying metallic sulphides 

in irregularly disseminated bunches and streaks. In the vicinity of Austin, the. oldest mining district in the 

f\tate, the veins are mostly in granite, and rich ores do not appear to occur in other rocks. In other parts of 

the range, however, the veins oceur in the stratified rocks. Besides quartz as a gangue mineral manganese 

spar and calc spar were noted, while thP metallic sulphides eomprise proustite, pyragyrite, stcphanite, polybasite, tetrahedrite, argentiferous galena, zinc blende, copper pyrites, and iron pyrites. In some of the veins 

the chief silver-bearing mineral is a mixed ~ulphide of antimony, as is the case in the neighborhood of Belmont. 

The veins are often faulted. 

As in the case with the orcs at Belmont, there is probably an intimate connection between the metalliferous 

quartz veins and the intrusive rocks. 

About 15 miles east of the eastern edge of the Silver Peak quadrangle is the 

southern Klondike district, which was noted by the writer in a previous publication.c 

At this camp the main country lock is Paleozoic limestone, which is intruded by a 

long dike-like mass of siliceous granitic rock of a composition similar to alaskite. 

The constituent minerals of the rock are chiefly quartz, orthoclase, and muscovite, 

and by various combinations of this rock types originate in different parts of the 

intrusive mass which may consist, essentially, of quartz and feldspar and so are 

alaskites; or of quartz, orthoclase, and muscovite, constituting muscovite granite; 

or, finally, of quartz and muscovite only, forming an igneous rock type which has not 

been previously fully recognized. The rock of the dike as a whole, however, is 

evidently closely related to that described by the writer from Belmont. Study of 

thin sections has shown the same derivation for the muscovite as that described from 

Silver Peak and Belmont. Occasionally in the igneous mass there are small segregated portions of pure quartz, in which patches of pyrite and more rarely of galena 

occur. The limestone near the contact has been altered to a hornstone, in which 

the microscope reveals fine epidote, zoisite, and other characteristic products of contact metamorphism. At the very contact of the igneous rock with the limestone 

there is in places a deposit of hard hematite, which has been partly derived from 

oxidation of original pyrite, of which residual portions still remain. Not many yards 

froJ.ll the contact in the altered limestone is a quartz vein which follows parallel to 

the contact closely for a mile or more and carries scattered values of silver and gold. 

a According to S. F. Emmons, Mineral industry: U. S. Geol. Explor. 40th Par., vol. :l, p. 398. 

b Spurr, J. E., Descriptive geology of Nevada south of the fortieth parallel and adjacent portions of Celilornia: I. ull. 

U.S. Geol. Survey, No. 208, 1903, p. 97. 

c Bull. U. S. Geol. Survey No. 213, p. 86. • 
• 

126 ORE DEPOSITS OF RJLVER PEAK QUADRANGLE, NEVADA. 

The minerals contained are chiefly galena and pyrite, with small bunches of the rich, 

black copper-silver sulphide or stetefeldtite, which has been described as character-

·istic of those veins in the Silver Peak quadrangle that lie near the contact of the 

intrusive granite, but not in the granite itself. 

All these mineral districts are· closely similar. In all the ores have evidently 

originated as the result of the intrusion of granitic bodies into Paleozoic sediments, 

and in all cases where a close study has been made it has been found that the ore 

deposition was associated with contact metamorphism. The granitic and alask[tic 

rocks which make up these intrusive bodies are similar in those districts which the 

writer has examined-namely, Silver Peak, southern Klondike, and Belmont-and 

from Mr. Emmons's description a also in the Toyabe Range. 

In the three districts which the writer has examined there are also similar 

pecularities of the intrusive rock, notably the segregation of small contemporaneous 

quartz masses within the rock and the alteration of feldspar to muscovite by magmatic 

processes. 

West of the Silver Peak quadrangle the Sierra Nevada is made up largely of 

granitic rocks, consisting mainly of granodiorite and granite. These rocks were 

intruded into the Paleozoic and Mesozoic strata in post-Jurassic time, probably 

contemporaneously with the similar intrusions in ~evada. Associated with these 

intrusions, partly in the granite, but more especially in the intruded sediments, now 

mostly metamorphosed into schists, are auriferous quartz veins, also post-,Jurassic in 

age, whose formation immediately succeeded the granitic eruption. In this region 

Whitney b noted that while the granite itself is not metalliferous its appearance seems 

to be closely associated with the metamorphism of the adjacent sedimentary rocks, 

while this latter condition is, as a general rule, the concomitant of the occurrence of 

minerals or metalliferous veins. Prof. ,J. F. Kempe remarks: 

The enormous introduction of silica is one of thf' most extraordinary featurt's of the geology of the Sierras 

and indicates a remarkable activity of circulating waters. The igneous intrusions doubtless promoted, if they 

did not cause, the circulations. 

Mr. Waldemar Lindgrend writes concerning the veins of a portion of this district 

(Nevada City and Grass Valley): 

It is not believod that the bulk of metals of the veins jg derived from the rocks immediately adjoining the 

vein. Their origin must still be left an open question; but the probability is strong that they wer~ dissolved 

from the more deep-seated parts of the granodiorite, whir.h appears to form the foundation of thE' Sierra Nevada, 

and brought to the surface by the thermal waters, the whole process being the closing chaptPr, the last manifestation of the abyssal granitic intrusions. 

Mr. Lindgren adds that the thermnJ waters were doubtless surface waters from 

the higher portions of the range which penetrated to a considerable depth before 

again reaching the surface. More recently, however, Mr. Lindgren has adopted the 

hypothesis that the solutions which deposited the veins are of magmatic origin. 

He writes e: 

aU. S. Geol. Explor. 40th Par., val. 3, p. 324. 

b rrhe Auriferous Gravels of the Sierra Nevada, p. 353. 

cOre Deposits of the United States and Canada, 3d ed., p. 370. 

d Gold-quartz veins of Nevada City and Grass Valley: Seventeenth Ann. Rept. U.S. Geol. Survey, pt. 2, pp. P5-176. 

e Characteristics of gold-quartz 'veins in Victoria: Engineering and Mining J ou;nal, March 9, 1905. · ' 
• 

COMPARISON WITH OTHER ORES. 127 

With some confidence I would formulate the hypothesis that the gold and the quartz in this type of Yeins 

have been deposited chiefly by" cruptivP after-effects;" in other words, chiefly by hot ascending waters ori'g~ 

in~tlly contained in the granitic magma and released from it by decreasing pressure, <iae to its eruption into the 

upper parts of tho lithosphcrP. It is quite possible that atmospherie waters may have played a certain part by 

aiding the precipitation and by effecting certain forms of concentration in tlw deposits. 

These gold-quartz veins of California are characteri:zed by the common occurrence of albite as a gangue mineral. F. A. Genth described, albite in pyritiferous 

gold-quartz veins in Calif~rnia,a and it has been noted as a Common occurrence by 

subsequent observers. b In. the Mother lode district Doctor Ransomec has described 

veins consisting almost entirely of albite with some quartz, and veinlets of albite 

alone; these in places contain bunches of free gold. In connection with the pre~ 

ence of albite in these veins the observations of Lehmann may perhaps be enlightening (p. 115). These observations indicate that the last attenuated granitic residue 

contains a great deal of soda, so that albite is deposited from it, along with quartz 

and other materials. 

The general conclusion is that the Silver Peak deposits are part of those contained in a larger province, represented more abundantly in the Sierra Nevada of 

California, with only outlying smaller areas in adjacent portions of Nevada. In 

these smaller areas, however, their isolated situation probably makes it possible to 

study the nature and origin of the deposits of the whole province better than in the 

larger occurrence. All the ore deposits of this province seem to owe their existence 

to the intrusion of the post-Jurassic granite, which now by erosion forms a large 

part of the main mass of the Sierra Nevada and occurs in less quantities eastward 

into Nevada. The ores seem to be due to siliceous solutions, which were residual 

from the later stages of crystallization of the granitic rocks. These solutions frequently deposited the minerals they contain (silica, gold, etc.) along fractures or 

shear zones or other channels, thus forming the typical gold-quartz veins of the 

regiqn. In Nevada these solutions formed in places where the wall rock consisted 

of the calcareous strata intruded by the granite a type of noble silver-gold veins 

(that is, veins containing a comparatively small amount of the baser metals) characteristic of the period. 

In studying the ore deposits of Tonopah, which lies only about 10 miles in a 

straight line east of the Lone Mountain district in the Silver Peak quadrangle, the 

conclusions were reached that the veins owed their origin to the action of magmatic 

waters and vapors, whose advent followed tho eruption of eertain Tertiary voleanic 

roeks. These waters and vapors were shown to be probably such· as appear at the 

surface in volcanie regions, in the shape of fumaroles, solfataras, and hot springs. 

The chief set of veins was deposited immediately after an andesitie eruption, and a 

less important set after a rhyolitic eruption. In the Tonopah report d analogies 

were pointed out between Tonopah and other districts in Nevada, and this comparison was extended to Idaho on the north and into Mexico on the south. Throughout this region ore is found in Neocene volcanics, and especially dependent upon the 

Miocene andesites and to a less extent upon the Miocene-Pliocene rhyolites. In all 

a Am. Jour. Sci., vol. 33, p. 249. 

b Ransome, F. L., Mother lode folio: Geologic Atlas U.S., folio 63, U.S. Geol. Survey, p. 8. 

c Op. cit., p. 9. 

d Prof. Paper U.S. Geol. Survey No. 42. 
128 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

these cases the ores were believed to have the origin described above for Tonopah. 

More than one period of mineralization, following diffeient volcanic eruptions, has 

thus been determined, but all these deposits are genetically connected with N eocene 

volcanics, and so have been grouped together. These deposits are characterized by 

certain common features in regard to gangue, ores, and alteration of the wall rock. 

On account of these characters these veins form a type of noble silver-gold veins, 

distinct from that of the silver-gold veins which have been described as connected 

with the granitic intrusions. 

The writer has characterized the region in which these silver-gold veins occur 

in the Neocene volcanics as a metallographic province. The interresemblance of 

the different ore deposits connected with the granitic intrusion in western Nevada 

is such as to justify rating this region as a metallographic province also. This 

province appears to be typically developed in California, for which reason we may 

call it the California province, while the province characterized by the ores in 

Neocene lavas is best represented east of the Sierra Nevada, in the State of Nevada, 

and may therefore be called the Nevada province. In western Nevada the Nevada 

province overlaps upon the California province, and along this overlap the ore 

deposits belonging to one group are superimposed upon those of the other. The 

Nevada province is coextensive with the appearance of Neocene andesites and 

rhyolites at the surface; the California province with the appearance at the surface 

of the post-Jurassic granitic rocks. Where, as in western Nevada, these granitic 

rocks and the strata which they include, together with the attendant veins, are 

exposed by erosion in patches lying in the midst of Tertiary volcanics, the veins 

belonging to the two periods may occur very close together. In the Silver Peak 

region Tertiary lavas overlie the granite and the post-Jurassic veins, but in this 

quadrangle no Tertiary vein formation has been discovered. 
CHAPTER IY. 

DEVELOPMENT OF TlLE 'l'III~OH 'l OF ~fETALLIFEHOUS VEIN8 

OF ~IAG:.MATIC qUAHTZ. 

The most important contribution to the theory of ore deposition made in the 

previous pages is the establishment of the fact that some auriferous quartz bodirs 

may be of magmatic origin and may, indeed, be regarded as a phase of granitic 

magmas. This conclusion supports the theory proposed by the writer in 1898 to 

explain the auriferous quartz veins of the Yukon district in Alaska.a At the time 

that this theory was formulated the writer had little knowledge of certain geological 

literature bearing upon the theory. The whole theory, including the transition 

of quartz veins to pegmatites and these to granitic rocks, was at that time original 

with him, but by continued study he finds that more and more of it had been anticipated, until practically the only portion left which he can consider as original is the 

conclusion that granitic quartz veins, which are really the ultra-siliceous form of 

the magma, may contain metals, especial!)" gold, in suificient quantity to constitute 

ores, and the corollary, later announced, that gold-quartz veins are especially 

connected with intrusive bodies of granitic rock.b 

In the following few pages an attempt is made to sketch the progress of thought 

by which the writer's theory has been in part anticipated, and there is added thereto 

some accumulated information bearing upon the problem. 

CRYSTALLIZATION 01'' GRANITE. 

Early in the nineteenth century it was po~nted out that the relative order of 

crystallization of the different minerals in granite was not that of their relative 

fusibility and that therefore the rock could not be due entirely to cooling from fusion. 

In 1822, Breislak c pointed out the difhculty above mentioned. 

If the granites arc crystallized by cooling, their constituents ought to separate and to crystallize at different 

epochs corresponding to their different degrees of fusib'lity. * * * 

Tt seems that sometimes the most fusible substance has crystallized before the less fusible one and is 

included in it. 

This objection having fallen into complete oblivion, M. Fuchs d recalled the attention of scientists to these phenomena. He vigorously pointed out the impossibility 

that the mixture of minerals found in granite should have crystallized from a condia Eighteenth Ann. Rcpt. U. S. Geol. Survey, pt. 3, p. 312. 

b Trans. Am. Inst. Min. Eng., vol. 33, p. 321. 

c Trait<\ sur Ia structure du globe, Paris, 1822, tome 1, p. 35G. Cited by Scheerer, Bull. Soc. Geol. France, 1846-47, 2d ser., 

lV, 1, p. 477. . 

d Surles theories de Ia terre, etc., Munich, 1844. Cited by Scheerer, op. cit., p. 477. 

13002-~o. 55-0tl--9 129 
130 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

tion of simple fusion. He remarked, moreover, that though crystals analogous to 

those of natural minerals have been formed in furnaces there had never resulted 

in this way a mixture like that of granite. 

. In 1833, Professor Scheerer visited Norway, before the objections of M. Fuchs 

had appeared and before he was acquainted with the views of Breisla.k. He observed 

that in pegmatitic granites it could be noted with certainty that the feldspars had 

crystallized before the quartz, showing that the quartz was still liquid, or at least 

pasty, while the feldspar was in process of crystallization. He concludedthat the most correct idea that can yet be formed concerning the origin of these rocks is that which attributps 

to the two elements fire and water an equal creative power. * * * One must admit that it is impossible 

to regard this rock as having been in a stat<> of purely igneous fluidity. 

Professor Scheerer pointed out that several of the minerals in granite contain 

water. He therefore reasoned that the magma must have had at least as much 

water as the solidified rock now contains. If it had had very much more, forming a 

humid base, such a magma would occupy a much greater space than the granite 

formed by its consolidation. The observed phenomena, however, show that dikes 

of granite occupy about the same space when cool as when in the magmatic form, 

showing that the proportion of water in the magma can not have been very large. 

He concludedThe quantity of water contained primitively in granite ought constantly to be between 1 and .50 per cent, 

and it is very probable that the amount is closer to the minimum than to the maximum. Here is an ttpproximate idea of the quantity of water in the granitic base. If one fixes it at 5, 10, or 20 per cent, it is almost the 

same thing. 

The substance of Scheerer's views has been corroborated by the most careful 

microscopical and chemical work since his time, without any very great advance in 

the general conception. Microscopical study has shown pooitively that in granitie 

rocks the order of crystallization is not that of relative fusibility, but for the commoner elements is rather that of relative basicity. As a rule the order of crystallization in granitic rocks has been found to be (1) dark minerals (amphibole and 

biotite), (2) feldspar, (3) quartz. On account of this relative order of crystallization 

it has been pointed out that if at any stage of the consolidation the minerals already 

formed are concentrated, rocks of all degrees of basicity may originate. Rosen busch 

rernarksa: 

Since the more basic compounds are in general the older, it is self-evident that the concentrations of eadierformed minerals and mineral combinations must have the mineralogical composition of basic rocks-that is to 

say, in a granitic rock, syenitic, dioritic, and gabbroid facies must form. If one considers this process as progressing further and further, it is seen that, together with the basic crystallized material, a continm111y more 

acid residual mJ,gtn:t will dev;>lop, which itself finally crystallizes, and we have then a sort of splitting up of 

the homogeneou3 eruptive magma into geologically closely related masses of basie and acidic rocks. 

~iAG~IA'.riC ORIGIN OF CEHTAIX PEGMA'l'ITES AND CERTAIN QUARTZ 

VEINS. 

The more siliceous varieties of granitic rocks, representing usually later phases 

of consolidation than the normal granites, have not always been thoroughly understood. Especially the coarse-grained facies known as pegmatites have been eona H. Rosenbusch, Mikroskopische Physiographie der Massigen Gesteine, 3d ed., Stuttgart, MlO@, p. 3.4. 
ORIGIN Olf CERTAIN PEGMATITJ<.;S AND QUARTZ VEINS. 131 

sidered by many students as vein formations subsequent to the granitic injections 

and due to quite different processes. This idea was due to the fact that these pegmatites are often found to be transitional into veins made up mostly of quartz, and 

because in other ways they showed many points of resemblance to veins for which an 

origin by deposition from circulating waters was nowhere denied. This conception 

as to the essential difference between pegmatites and granites depended primarily 

upon the false conception which still lingers in the minds of geologists, although long 

ago shown to be incorrect, that granite is a simple igneous rock, solidified from a 

molten condition, and that other conception, which also is still firmly intrenched in 

the minds of many geologists, that all veins are due to deposition from waters which 

everywhere traverse the rocks and which have not necessarily any close genetic connection with igneous magmas. It is now, however, acknowledged by many that 

there is no critical line between granites and certain quartz veins nor between the 

processes by which they were formed. Between the granites and the quartz bodies, 

pegmatites often form an intermediate step. The terms" igneous" and "aqueous" 

for the processes by which the two ends of this transition series were formed is misleading, nor do the three terms which have been proposed, "igneous," "aqueoigneous," and" aqueous" express the truth, for, according to the writer's conception, 

there is no sharp line at any point. At one end of the series the true granites are not 

wholly igneous, and at the other end the quartz veins arc not wholly aqueous. The 

processes which formed them all are nearer together than these terms signify. 

In 1823, Charpentier a came to the conclusion that the granitic pegmatite dikes are 

fissure dikes "which were formed simultaneously with, or at least very soon after, 

the consolidation of the inclosing granite." 

In 1838, Keilhau b took the view that certain Norwegian pegmatite dikes nre not 

fissure fillings but are dike-like segregations from the sycnitic rock~ in which they lie. 

This view was afterwards expressed also by Hausmann." 

The views of Scheerer,a published in 1846-47, and above referred to, concerning 

the crystallization of granite had some connection also with the theory of pegmatites. 

He wrote: 

There are frequently found, in granite and primitive gnPiss, cavities whoso walls ttr0 covered with crystals 

of different varieties. * * * vVe observe the same phenomena in a certain dass of veins that are found 

in granitic and other rocks. It can be recognized in an almost materirrl mrrnner that their filling has been 

ttecomplished by the deposits of solutions or of juices which haw escaped from thc1 inclosing rock. That is 

why they are called segregation veins lfilons de secretion). 

In sum, the attentive ohservPr of granitic rooks can not avoid the id<:>a that these contain, so to speak, a 

juice, which, running into the caYities and fissures, covers their walls with crystals. This juice penetrates 

more or less into the stratified rocks th>'lt the granite comes in contact with in its plasti'\ state, and penetrating 

them, and thereby favoring their metamorphism, it tttkes a greater or less part in the formation of contact 

products. The fluid impregnating the wt~rm mass of the granite could hardly be anything than water at a very 

high temperature, but nevertheless maintained in a liquid state and capahlP of f'scaping in tiny drops under 

an enormous pressure. It would contain in solution part of the solid substances and esperially ~ilica. 

Although views like those cited above first obtained in regard to the origin of 

pegmatitic rocks, another theory was subsequently developed which for some time was 

• Essai sur Je constitution geognostique des Pyrenees, p. 158. Cited by Brogger, Zeitschr. fiir Kryst., vol. 16, p. 215. 

b Groa Norvegica, I, 58. Cited by Brogger, op. cit., p. 220. 

c Cited by Br5gger, op. cit., p. 221. 

d Op. cit., p. 493. 
132 ORE DEPOSITS OF SILVER PEAK QUADHANGLE, NEVADA. 

predominant both in America and Europe. This was the theory of lateral secretion, 

by which the origin, both of pegmatitic rocks and metalliferous veins, was explained. 

The application of this conception to the explanation of pegmatites was probably 

first made in 1863 by T. Sterry Hunt,a in connection with his studies on Canadian 

pegmatites, and developed in succeeding essays. 

Later, in 1875, H. Credner b came to the same conclusion in regard to the origin 

of the pegmatitic rocks of Saxony. He concluded that the material of these granitic 

dikes had not been intruded from below and, had not even been formed by hot 

mineral springs, but were due to seepage water which had partially decomposed and 

leached the country rock to furnish the pegmatitic minerals. 

In 1869, G. Kreischer c adopted for certain pegmatitic rocks an explanation 

similar to that of Hausmann above cited, namely, that they were of contemporaneous 

origin in the inclosing igneous rock. 

In 1881, G. vVoitschach<l came to the same conclusion concerning certain Ger_ 

man pegmatites that was reached by Kreischer and Hausmann. Similar views have 

been taken by other authors, such as Kalkowski e and Teall/ 

In 1884, Dr .• J. LehmannY published his studies concerning the pegmatites of Saxony. He took a decided stand for the igneous and magmatic origin of these rocks, 

vigorously opposing the explanations of Credner. The phenomena which seem to 

have led Credner to his belief consisted of certain evident relations between different 

wall rocks and the pegmatites which they inclose. Doctor Lehmann acknowledged 

this relation but pointed out that it was of minor importance and that all the pegmatites must be referred to the granitic magma.h Doctor Lehmann went further, 

in announcing that the quartz veins or dikes (Gange) associated with the pegmatites 

are also a phase of the granite magma. He writes: i 

If one goes from cmptive granites and the lesser dikes to the pegmatites, and farther on to the dike formations which are poor or lacking in feldspar, one easily comes to consider cPrtain quartz veins as eruptive injections. * * * To be sure, if one confines hi1IlSelf to words and considers thP eruptive masses only in connection with high tempcmture and fusion, then it is clear that tht>st> quartz vPins or rlikcs can not have originated 

in this way. The granite magma is, how<'ver, essentially different from those magmas which reach the earth's 

surfact>. * * * 

Doctor Lehmann added many individual descriptions and arguments to fortify 

his conclusions, describing many phenomena which find their parallel in the Silver 

Peak region of Nevada. Speaking in general of the granitic dikes of his province, 

Doctor Lehmann writes: i 

In connection with the increased sizP of_ the constituPnts, now one, now another, of tlwm predominates. 

Here the quartz become3 subordinate, there the orthoclase. Dikes which ar<> meters thick and consist of predominant clear or milky quartz, in which are Prnbcdded only occasional feld-.par, tourmaline, or mica crystals, 

a Cited by Brugger, Zeitschr. fiir Kryst., 1890, vol. 16, p. 216. 

b Zeitschr. doutsch. geol. Gesell., Berlin, 1875, vol. 27, p. 34. Cited by Brogger, Joe. cit 

c Ncues Jahrbuch fiir Min., 18(i9, p. 209. Cited by Brogger, op. cit., p. 221. 

d Cited by Brogger, op. cit., 221. 

e Zeitsch. deutsch. geol. Gesell., 1881, vol. 33, p. 653. Cited l>y Brogger, Joe. cit 

f British Petrography, p. 291. 

g Die Enstehung dcr Altkrystallinschen Schiefergestcine, Bonn, 1884. 

h The influence of different wall rocks in producing more or less characteristic types of minerals and mineral associations 

in pegmatites which form phases of granitic intrusions has also been studied by. Mr. S. H. Ball in the region of Georgetown, 

Colo. (Report not yet published.) 

i Op. cit., p. 25. 

i Op. cit., p. 47. 
ORIGIN OF CERTAIN PEGMATITES AND QUARTZ VEINS. 133 

seem to be very widely separated from true granite, and yet they belong to the granite formation of our mountains. These feldspar-bearing quartz veins, as well as those quartz vein~ in which, together with quartz, only 

tourmaline or only mica or albite arf\ pre~ent, must have originated in the same way as the granite dikes proper 

'or at least in a manner related to this and only modified. The opening up of the dikes to form mineral druscs 

is also not against the idea of an origin hy injection. 

He adds: a 

We shall never grasp the meaning of the formation of granite in the region of the old crystalline schists if 

we do not trace up all the forms in which the granite magma can appear. To be sure, not every occurrence of 

granite is favorable for this study. * * * 

Every conception of a granite magma must in the first place take note of the silicic acid which has separated out as quartz, and on this account in the past the presence of quartz has created the greatest difficulties 

and aroused the greatest attacks. 

Elevated temperatures and heavy pressure wEre doubtless operative at the origin of the granite, and also 

a role must be ascribed to the intermixed water and other condensed volatile materials, which must b~ regarded 

as belonging to the granite magma in the beginning and can not have been brought to it from above. * * * 

We see in the neighborhood of great granit<' dikes and masses, certain impregnations and dike fillings as the 

result of their splitting up. These mineral depo,its, since they did not reach the surfa~e, must ha.-e had a 

fluid magma-like or aqueous vehicle. * * * These fluid secretions of the granite, which are equivalent to 

the gaseous and vaporous secretions of the lavas, can well be likened to hot jellies which wlidify in cooling with 

a very variable water content. The ability of silicic a~id to form jellies with little or with much water main's 

this conception attractive. The combination with boric and carbonic acid, fluorine, and other volatile materials 

is certainly also to be considered. Such a jelly-like magma must hav0 bc>en capable of crystallization through 

cooling, and according to tl1e degree of the burden of the mineral materials which it carried must han' fillf'd 

the space more or less completely with its crystallization products. Tf it contained great amounts of components which remained fluid (and that must havE' been mostly wat<'r, besides gaseous products), then the character of the solution must have hccome more and more altcrPd through successi\·c precipitation, and a part of 

the mineral material may have attained greater distances from the original point than the part which Parly 

separated out as feldspar. Between such a jelly-like magma and a saturatf'd aqueous solution we can think 

of a long series of transitional steps. In this way it seems to mc that the connection of pcgmatitic dikes with 

granular granites, as well as the very remarkable transition in the crystallization of the pegmatitic dihs, which 

often contains druses,;md finally the close connection of these with dike fillings, which consist only of quartz, 

tourmaline, and muscovite or of quartz alone, lwcomes explicable. * * * 

Those dikes in our mountains which <'onsist mostly of quartz and inelose feldspars as large> ns one's 

hea.d. * * * can only have been formed simultaneously in a fluid mass. The rna" which fills them contradicts with sufficient distinctness the ide~t of a precipitation from attenuated solutions and from ordinary 

seepage water. "\Ve have furtlwr, also, the tc.stimony of Gumbel. Dclcsse also declared that, under great 

pressure and through mixture of watcr, quartz softens in the interior of the earth--that is, it may go over into 

a viscous gelatinous silica-in which process a temperature which is not extraordinarily high may have 

assisted. Obsf'rvat.ions whid1 can not bo otherwise explained are reported from numorous sources. Tlwrefore since viscous silicic acid can unite itself with any given amount of water, it. is not wonderful that when 

it goes over into the crystalline condition the quartz fills up the space Pntirely, if only a little watf'r was 

intt>rmingled; and that in the same mass, when it is burdenPd with a greater amount. of wnter, the material 

on separating out form> druses, assumes the form of nrrkcd incrustations, and finally does not differ from the 

material separated out from ordinary aqueous solutions and mingles with thest. 

These detailed observations of Lehmann have been repeated frequently, and often 

made independently without knowledge of previous investigations, so that a constantly accumulating mass of evidence has been formed, though not much has been 

added to the results of Lehmann's investigations. 

In 1887 A. W. Howittb published important studies concerning pegmatitic rocks 

in Victoria, Australia. This is a region of auriferous quartz veins, which occur 

a Op. cit., p. 52. 

b Notes in the area of intrusive rocks at Darga: Trans. Roy. Soc. Victoria, vol. 23, p. 127 et seq. 
134 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

characteristically near the contact of masses of intrusive granitic and dioritic rocks 

which have broken through and metamorphosed Paleozoic sediments. Mr. Howitt 

draws a distinction between these auriferous quartz veins and other veins of quartz to 

which he assigns a pegmatitic origin. He does not, however, give any criteria for 

distinguishing the two classes of veins save that one is auriferous while the other had 

not been proved to be so. These two classes of veins occur both at Dargo and Omeo. 

The auriferous quartz veins contain pyrite, arsenopyrite, galena, and gold. The 

quartz veins which he classes as pegmatitic consist either of quartz alone (milky or 

translucent) or of quartz containing tourmaline, feldspar, or muscovite, "or two or 

all of them together in varying proportions, so that veins may be extremely quartzose 

with but little proportion of other minerals or may be so charged with them as to 

become a variety of pegmatite." 

From study of these veins Mr. Howitt found that the tourmaline crystals are 

frequently isolated in the midst of the quartz, which is molded perfectly around them 

and even fills cracks which had formed in consequence of their breaking. The 

isolation of the tourmaline indicates that the quartz was not deposited from solution, 

but was a denser plastic mass, 'which yet was capable of some movement under 

pressure. Mr. Howitt concluded that tho quartz had been forced into the fissures in 

a colloidal condition. 

It geems to me, therefore, more than probable that such quartz veino as these represent some of the residual 

silica of the plutonic magma after the compound minerals had crystallized out, and that this residuum was 

squeezed out while in a colloid state into every adjoining fissure and plane of separation. No high temperature would, on this view, be necessary to produce these dike-like quartz veins, for the exudation of the still 

colloidal silica was brought about by the redu~tion of temperature, which caused the plutonic magma to 

solidify.a 

In 1888 Mr. Howittb came to the same conclusion for another group of rocks in 

this region. He writes: 

The granites, therefore, taken as a whole, including all the above v:triPties, represent an intru~ion of plutonic rocks of several consecutive ages of the same period of plutonic inn1sion, and the series is increasingly 

acid, the later dikes being mainly of orthoclase (microperthite) and muscovite or of orthoclase and quartz. 

Finally, the veim and even strong dikes of crystalline quartz or of quartz and tourmaline (schorl), which are 

associated with these granites, represent thf' last portions of still fluid (uncrystallized] magma. 

In 1890 W. C. Brogger c published some studies on Norwegian pegmatites. 

Brugger argues that the pegmatitos of his district are essentially intrusive and magmatic, but differs from Lehmann as to the origin of the granitic quartz veins, which 

he (Brogger) regards as exudations from the solidifying magma. He acknowledges 

the transition between the quartz veins and the pegmatites, but regards the two as 

forming differen:t classes. The pegmatite he regards as the last stage of consolidation 

of the granitic magma. The transition between this and true granites he says is 

perfect, the series being granitites, granophyres, aplites, and pegmatites. The 

quartz veins into which the pegmatites are transitional, and which follow the pega Mr. Howitt, in spite of the evidence which he has set forth in regard to the plutonic origin of many of the quartz veins 

in the auriferous districts, and in spite of the fact that he has shown the auriferous quartz veins to be connected with the 

intrusive granite contact, turns his face from these phenomena when he attempts to explain the origin of the gold in the 

auriferous quartz. He goes back to the old theory that the veins aredue to circulating waters which have derived their 

silica and their gold from the Silurian strata through which they have percolated, and that the gold was originally contained 

in the Silurian ocean and was precipitated in the sediments of that period. 

b Notes on certain metamorphic and plutonic rocks at Omeo: Trans. Roy. Soc. Victoria, vol. 24, pt. 2, p. 100 et seq. 

c Die Mineralien der Syenitpegmatitgange: Zeitschr. fiir Kryst., vol. 16. 
ORIGIN OF CERTAIN P:EGMATITES AND QUARTZ VEINS. 135 

matites in point of time, do not, nevertheless, belong to this series, but are fissure 

fillings which are not entirely or not at all due to precipitation from true magmatic 

solutions.a He divides the formation of the pegmatites into four stages. b The first 

period, the phase of magmatic consolidation, yields certain minerals, among which 

the principal ones are apatite, titanite, zircon, magnetite, lithia-mica, fluorite, and 

feldspars, deposited in about the above order. The second period of minerals comprise those formed chiefly by the influence of mineralizers, or deposited from circulating fluids. These are minerals rich in fluorine, boron, and sulphur, such as 

fluorite, tourmaline, molybdenite, zinc blende, pyrite, galena, and copper pyrite. 

Zircon and albite also occur among the minerals of the second period. The third 

stage is that of zeolite formation, and the fourth that of fluocarbonates and 

carbonates. 

In 1894 A. C. Lane c called attention to the fact that "there is a continuous 

series from pegmatites to segregation veins and true fissure veins filled by ascent. 

* * * Pegmatites are one form of residual magmas, the segregation veins a 

further step." 

In 1895 G. H. Williams d discussed the origin of Maryland pegmatites. He 

concluded that many of these pegmatites were intrusive and an integral part of 

granitic intrusions. Another class of pegmatites, however, which he admits is not 

distinctly separate from the intrusive pegmatites in point of composition or appearance, he believed to have a different origin, on account of their being transitional 

into typical quartz veins. Such pegmatites he considered to have been formed 

by lateral secretion from the inclosing rock, for no one, he believed, could doubt that 

the vein quartz into which such pegmatites are transitional have this origin. 

In 1896 C. R. Van Rise recorded the transition in the Black Hills from granite 

to pegmatite and from pegmatite to quartz veins. He believed e that pegmatites 

in different cases have been due to three processes: 

In some cases igneous injection, in some cases aqueo-igneous action, and in other cases pure water cementation, and in still others combinations of two or all of these processes. 

The transition from granites to quartz veins which he has noted he appears to 

consider as marking these stages between true igneous injection and aqueous cementation. The water concerned in these processes he did not refer to the magma 

especially, but to the underground water in general, in the belief that under sufficient 

pressure and temperature magma and water are miscible in all proportions. 

In 1897 W. 0. Crosby and M. L. Fuller f contributed the most important essay 

on pegmatites which has appeared in American literature. They described cases 

in New Hampshire where there was a perfect gradation in composition between 

typical pegmatite and quartz veins. The quartz veins have locally cut the pegmatite and are therefore younger, but are nevertheless probably substantially contemporaneous with the quartz which is an integral part of the pegmatite. They dissent 

a Op. cit., pp. 226-232. 

b Op. cit., pp. 160-174. 

c Geologic activity of the earth's originally absorbed gases: l3ull. Geol. Soc. America, vol. 5, pp. 259-280 

d Fifteenth Ann. Rept. U.S. Geol. Survey, p. (\75 et seq. 

e Sixteenth Ann. Rcpt. U.S. Geol. Survey, pt. 1, p. 686. 

American Geologist, val. 19, No.3. 
136 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

from Williams where he maintains that the pegmatite which is transitional into quartz 

veins has a different origin from the rest, and maintain that this transition is an 

obvious and frequent relationship, and that the quartz veins are the end product of 

the same great process of differentiation which has produced the pegmatites. They 

propose a theory that pegmatites may be formed in two ways: First, by normal 

magmatic differentiation in a large body of magma. In this case the pegmatite, 

where it is still in its original place of differentiation, may pass gradually into normal 

granite, or the pegmatite magma may migrate, crystallizing in fissures in the parent 

granite or the surrounding rock. As another possible mode of formation, they 

believe that when apophyses of normal granitic magmas invade heated aqueous rocks 

and become hydrated their magma becomes a pegmatitic one. 

In 1898 J. E. Spurr a observed the transition from quartz-feldspar rocks (to 

which he later gave the name alaskite) to quartz veins. b These quartz veins contain pyrite, argentiferous galena, and free gold. 

In 1898 F. D. Adams c described some interesting nodules and veins in granite 

from Ontario. In this granite are spherical or oval quartz nodules containing tourmaline. In some places these nodules are arranged in rows, and along some portions of a given row the nodules may join, forming what appears to be a true vein. 

The chief constituents of the nodules are quartz, muscovite, and sillimanite. Sometimes plagioclase and orthoclase are present, and again tourmaline, iron ore, and 

pyrite. Professor Adams regards this as a case of primary magmatic differentiation and compares the veins to the quartz veins, frequently associated with tourmaline, which are transitional from pegmatites, and occur in connection with many 

granite magmas. 

In 189\J Otto Nordenskji)ld d observed, in the Klondike region, transitions such 

as Mr. Spurr had described from the near-by Fortymile district of the Yukon province. 

These transitions were from granites to pegmatites and perhaps into pure quartz 

veins. Nordenskjold, however, did not observe gold nor pyrite in these rocks. 

In 1901 J. F. Kemp c wrote that on the north shore of I.,ong Island Sound 

"pegmatites are abundantly developed in connection with granites, and all grades 

are shown up to practically pure quartz." 

In 1903 J. E. Spurr/ noted the transition at Silver Peak, Nevada, from 

granitic rock into quartz veins. Mr. H. W. Turner had made the same observation 

independently. Mr. Spurr also noted the transition from quartz veins into granite 

at various other places, including the vicinity of Oro Grande on the Mojave River 

in southern California, in northwestern Nevada in the Walker River Range, and near 

Randsburg, Cal. 

G. A. Waller and E. G. Hogg described in 1903 g some interesting quartztourmaline dikes in Tasmania. In the region described a granite is intrusive into 

a Eighteenth Ann. Rept. U. S. Gcol. Survey, pt. 3, p. 312. 

b Am. Geologist, April, 1900, p. 229. 

----~--- -~ ~~~- -~~~~-

c Nodular granite from Fine Lake, Ontario.: Bull. Geol. Soc. America, val. 9, pp. 163-172. 

d Die Geologischen Verhaltnisse der Goldlagerstatten des Klondikegebietcs: Zeitschr. fiir prakt. Geol., March, 1899, pp. 

71-83. 

e The rOle of the igneous rocks in the formation of veins: Trans. Am. Inst. Min. Eng., vol. 31, p. 182. Genesis of Or~ 

Deposits, p. 693. 

f Trans. Am. Inst. Min. Eng., val. 33, p. 313. 

g The tourmaline-bearing rocks of the Heemskirk district: Report of the Secretary for Mines of Tasmania, 1903. 
ORIGIN 01<' CERTAIN l'EGMATITES AND QUARTZ VEINS. 137 

metamorphosed Silurian sediments. The granite contains tourmaline throughout, 

usually associated with the quartz. Nodules of quartz containing tourmaline 

and a little feldspar occur in the granite, either isolated or collected in masses, and 

seem to correspond with the phenomena described by Doctor Adams, above cited. 

In connection with the granites, tourmaline aplites occur, which ar-pear to represent 

a differentiation product of the granite. The aplites contain quartz-tourmaline 

nodules in greater abundance than the granite. Rocks consisting entirely of q'~'artz 

and tourmaline are frequent, and are divided by the authors into dikes and veins. 

The quartz-tourmaline veins consist of quartz and tourmaline with, as lesser constituents, cassiterite and pyrite, as well as some bismuthinite, molybdenite, pyrite, 

chalcopyrite, galena, zinc blende, and fluorite. The veins are partly due to the 

filling of fissures and partly have originated by replacement of the wall rock. The 

dikes consist of a uniform granular mixture of quartz and tourmaline, with sometimes a little feldspar. The tourmaline is older than the quartz. These dikes 

often contain included angular fragments of the country rock. In some cases 

quartz has segregated, so that the dike is of white quartz, almost free from tourmaline. It seems evident that the tourmaline is an original constituent of the granite 

magma, since it is present in all the rocks. The local increase in amount of tourmaline is accounted for by a process of differentiation in the magma, and the quartztourmaline nodules arc accounted for by a similar process. This quartz-tourmaline 

magma, collecting together, has formed the quartz-tourmaline dikes. The quartztourmaline veins are accounted for by a further magmatic separation, which has 

separated a highly aqueous from a less aqueous magma. From the former, which 

would frequently be a saturated solution, highly heated and containing boron, 

fluorine, and hydrogen sulphide, the quartz-tourmaline veins and the metamorphism 

of tj:w wall rock are supposed to have resulted. The magma, which formed the 

quartz-tourmaline dikes, however, seems to have been in a viscous condition. 

In 190:3 Cross, Iddings, Pirsson, and Washington a recognized the transition 

from granites to quartz veins and recognized the fact that such quartz veins belong 

in tho category of igneous rocks. The name of dargase is here given (p. 265) to a 

certain type of rocks transitional between granite and intrusive quartz veins. 

These rocks arc referred to as described by Howitt from Dargo, Victoria, Australia. 

In the articles by Mr. Howitt, above cited, however, there is not found any analysis 

of the rock in question. 

A. C. Lawson b in 1904 described aplite dikes cutting a hornblende gabl_>ro. 

These dikes grade into facies so siliceous as to be practically quartz veins, and on 

the other hand into veins of feldspar. 

C. R. Van Hise c in 1904 repeated his conclusions, above cited, as to the origin 

of pegmatites. In regard to the water concerned in the process of pegmatitization 

he states thftt a considerable part, in some cases most of it, is derived from the magma 

itself, while in perhaps the greater majority of cases the water has been derived 

from the surrounding rocks. Van I-Iise (pp. 1048-1049) here takes the view that 

auriferous quartz veins can not be in any case a final phase of granitic intrusions -~~~------~ ------· ---

a Quantitative classification of igneous rocks, Chicago, 1903. 

b The orbicular gabbro at Dehesa, San Diego County, Cal.: Bull. Dept. of Geol., l.iniv. California, vol. 3, No. 17, p. 388. 

c Mon. U. S. Geol. Survey, voL 47, p. 720, et seq. 
138 ORE DEPOSITS OF SILVl<:R PEAK QUADRANGLE, NEVADA. 

and doubts whether metals other than those of iron and aluminum have been 

formed by magmatic segregation, on account of the enormous amount of segregation 

required. 

In 1905 J. E. Spurr and G. H. Garreya described for the area near Georgetown, 

Colo., the frequent transition of pegmatites to quartz veins, both being phases 

of granitic intrusions. b 

In 1905 E. C. Andrews c described pegmatites and quartz veins, grading into 

one another, as consolidating phases of granitic intrusions in New South Wales, 

Australia. 

In general the writers' opinions as to the origin of pegmatites and pegmatitic 

quartz veins are very close to those held by Scheerer, Lehmann, Howitt, and Crosby 

and Fuller. 

CONCENTRATION OF UE'l'ALS OTHER THAN GOLD IN DIKES OF 

GRANITIC PEGMA'l'ITE AND OJ<' Q~AR'J'Z. 

One of the most obvious characteristics of pegmatites, and one which has always 

been noticed in every study is the concentration in them of the rare as well as the 

commoner elements. Elements such as wolfram, lithium, tantalum, tin, etc., are 

frequent and are often concentrated to a great extent. These rare elements include 

some of the more common metallic ores. Brugger d in his study of the pegmatites 

in Norway found magnetite, molybdenite, zinc blende, pyrite, galena, and copper 

pyrite as primary minerals in pegmatites. 

IRON IN PEGMATITE. 

S. L. Penfield and E. H. Forbese described in pegmatite, at Rockport, Mass., 

a lenticular shell of magnetite about 1 inch thick surrounding fayalite. 

A. C. Spencer fin 1904, after studying the magnetite deposits of Sussex County, 

N. J., concluded that the magnetites are connected in origin with intrusive dioritic 

pegmatites. All the deposits are referred to a single genetic type, probably including 

the zinc-bearing deposits at Franklin Furnace. The pegmatite is most often composed of oligoclase with some hornblende and occasionally mica. Quartz and 

microcline are sometimes present. Accessory minerals are garnet, apatite, sphene, 

spinel, allanite, and magnetite. Magnetite occurs in grains in all the igneous rocks. 

Masses of magnetite and hornblende occur associated with pegmatites in such a 

way as to lead to the conclusion that both have originated by segregations connected with the invasion of the pegmatite. 

J. E. Spurr and G. H. Garreya described in 1905 magnetite-bearing pegmatites 

from the Georgetown, Colo., region: 

a Bull. U. S. Geol. Survey No. 260, p. 104. 

b In 1903 Mr. Whitman Cross observed in the Pikes Peak region, Colorado, many cases of quartz veins transitional into 

pegmatites, which in turn were transitional into the intrusive granites. 

c Records Geol. Survey New South Wales, 1905, vol. 8, pt. 1, pp. 108-152. 

d Zeitsch. fiir Kryst., vol. 16, pp. 163-164. 

cAm Jour. Sci., 4th scr., vol. 1, 1896, p. 129. 

I Mining Magazine, vol. 10, No.5, Dec., 1904. 

.. 
METALS OTHER THAN GOLD IN CERTAIN DIKES. 139 

The pegmatites c~ntain varying proportions of one or more of the following minerals: Quartz, fPldspar, 

biotite, and mnscovitP. Magnetite and pyrite are ~ommon accessory mim>rals. Occasionally the pegmatite 

consists almost entirely of white or red feldspar, while at other times it assumes the phase of veins composed 

essentially of pure quartz cutting older rocks. The pegmatites are usually rathPr acid, but magnetite is frequently found in them in large quantities.' The granites and other igneous rocks often contain magnetite as 

an accessory constituent, but the magnetite is vastly morP abundant in the pegmatite than in the other rocks. 

Places were observed were the segregated magnetite in the pegmatite or in the quartz veins of pegmatitic 

origin was nearly equal in volume to the rest of the rock mass, and in consequence almost formed an iron ore. 

Pyrite is also a prominent original constituent of the pcgmatitcs at times. 

COPPER IN PEGMATITE. 

J. F. Kemp a in 1901 described pegmatites in gabbro near Princeton, Yale 

district, British Columbia .. The pegmatite is connected with bornite, which forms 

an ore there. The bornite sometimes occurs in separate streaks and sometimes 

in pegmatite, in which it seems to be an original mineral. 

A. C. Spencer b in 1904 described copper-bearing pegmatitcs from the Encampment district, vVyoming. In one case microscopic examination indicates that the 

copper is later in origin than the rest of the pegmatite, and so may, perhaps, represent a subsequent process. In other copper-bearing pegmatites the copper ore, 

which is chalcopyrite, largely altered to chalcocite ncar the surface, has 'forrncd at 

the same time as the quartz of the pegmatite, while both are somewhat later than 

the feldspar. 

Jules Catherinetc in 1905 confirmed Kemp's views in regard to the copper ore in 

the Yale district of British Columbia. The pegmatite, he says, does not differ 

markedly from other occurrences of this rock, except that it contains bornite. The 

chief feldspar is orthoclase with some oligoclase. Tourmaline, fluorite, and calcite 

are occasionally found. Careful study ·warrants the conclusion that the bornite is 

an original mineral to the same extent as the mica and the feldspar. This pegmatite 

also contains gold and platinum, the former in a native state, the latter in the form 

of arsenide and sperrylite. The two minerals occur in flakes in the bornite and in 

the chalcopyrite and also in the orthoclase, where they form minute particles which 

give the impression that the two minerals arc in the rock as original components. 

It is regarded as possible that the chalcopyrite may be an alt~ration product of the 

bornite. 

TIN, TUNGSTEN, MOLYBDENUM, ANTIMONY, BISMUTH, AND LITHIUM IN 

PEGMATITE. 

Tin ore is of frequent occurrence in pegmatite. In thl; Black Hills of South 

Dakota, according to Mr. S. F. Emmons,d the tin deposits occur in an area of coarsegrained granite. The Etta mine deposit, the only one that has produced any considerable quantity of tin, is a lenticular body of pegmatitic granite, which consists of 

quartz, albite, lepidolite, and spodumene individuals of great size up to 8 or 9 feet in 

dimensions. Cassiterite occurs in connection with lithia mica and is accompanied 

by columbite and tantalite. 

a Trans. Am. Inst. Min. Eng .• vol. 31, p. 182. 

b Prof. Paper U. S. Gcol. Survey No. 25, pp. 41 and 95. 

c Eug. and Min. Jour., val. 79, No.3, p. 125. 

d Cited by A. J. Collier, in Tin deposits of the York region of Alaska: Bnll. U.S. Gcol. Survey No. 229, 1004. 
140 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NRVADA. 

In the Moolyella tin field of Western Australia a the whole area is of granite, 

which is traversed by quartz veins and pegmatites. The pegmatite is made up principally of qtiartz, albite, and a little niica, together with a few garnets and cassiterite. 

The tin occurs in greatest quantity in alluvial deposits, where the mineral is derived 

from the erosion of the pegmatite and also as a result of the decomposition of the 

pegmatite in situ. Residual or surface tin may be found wherever the pegmatite veins 

are numerous. 

In the Greenbushes field, western Australia, the rocks are largely crystalline, 

granitic, and gneissic, cut by dikes of diorite, tourmaline granite, and pegmatite. 

Some of the pegmatite dikes contain a little less than 2 per cent of tin. V cins up to 

2~ feet wide, carrying tin and much tourmaline, occur in the granite. Zircon, garnet, 

monazite, and considerable amounts of niobates and tantalates occur with the tin.~> 

In northern New England, which is in the northeastern part of New South 

Wales, Australia, the mineral-bearing veins, according to :Mr. E. C. Andrews,c have 

a close genetic relation to siliceous granites intruded at the end of the Paleozoic era 

and the beginning of the Mesozoic, and are almost always arranged peripherally with 

respect to the bodieo; of granite. An important group of these veins consists of pegmatite grading into vein quartz, and such veins are considered as phases of the 

granitic intrusion, representing the later stages of consolidation. These veins contain tin, tungsten, molybdenite, antimony, and bismuth, and are of great economic 

importance. Gangue minerals include quartz, feldspar, tourmaline, fluorite, beryl, 

black mica, ehlorite, sericite, monazite, emerald, and topaz. Copper pyrite and 

arsenical pyrite also oceur. 

M. L. De Launay d furnishes some interesting notes upon pegmatites carrying 

original lithia miea, cassiterite, and antimony in the Central Plateau region in France. 

He writes: 

The rleposit at l\lontebras, formerly exploited for tin, constitutes to-day the only industrial source in the 

world of amblygonite, a mineral utilized by the production of lithia, of which it contains 6 to 8 p<'r cent. * * * 

So far as one can judge, it seems that the amblygoni.te is associated with quartz and cassiterite in tlwir regular 

veins, which cut a porphyritic granulite. * * * This sam<' granulite, which is encountered discontinuously 

in a rather pxtensive zone (from 800 to l ,.500 meters) which is slightly staniferous throughout, incloses elsewhere other veins of the same kind, in which epidote predominates and sometimes cassiterite. 

Professor De Launay, eontinuing, describes briefly a number of tin-hearing veins 

in this same distriet and closes with the following statement: e 

In a general way it seems that the cassiterite-bearing veins, as well as those containing amblygonite, are 

only a peculiar phase of the pegmatitcs, in which these useful minerals play the same role as the quartz, feldspar, 

and muscovite. It is to be remarked, moreover, that in the ordinary pq:;matites at Monte bras, even when tin 

is not visible, it nearly always exists finely disseminated in quartz in sufficient quantity to render the quart& 

unfit for use in the manufactme of glass. 

In the same general region Professor De Launay describes an antimony mine in 

pegma ti tes :! 

a Maitland, A. Gibb, Geological features and mineral resources of the Pilbara gold field: Bull. Gcol. Survey of \Ycstern 

Australia No. 15. 1904, p. 102. 

b Cited by F. L. Hess. Occurrence and distribution of tin: Bull. U.S. Geol. Survey No. 2GO, p. 172. 

c Records Geol. Survey New South Wales, 1905, vol. 8, pt. 1, pp. 108-!52. 

d Excursion a quelques gites mine.raux et metalliferes du Plateau Central: Extrait du Compte-Rendu du VIlle Congres 

geologique International 1901, Paris, 1901, p. 10 ct seq. 

e Op cit., p. 15. 

I Op. cit., p. 16. 
METALS OTHER THAN GOLD IN CERTAIN DIKES. 141 

The little antimony deposit at :\Iontignat is only interesting as an example of the very numerous stibnite 

deposits that are scattered in the Central Plateau. * * * 

There is in this place, in thA midst of the very granitic gnl'iss, which has a granular, slightly banded structure, and is often difficult to distinguish from a granitR proper, a dike of~ special variety of granulite. * * * 

Thl' maximum thickness of this dike is 8 meters. In it stibnite is found localized in tlw form of a stockwork 

of stibnite-bearing quartz. * * * The dike itsPlf is very regular, but the antimony-bearing vein lets in its 

mass are, on the contrary, ver)· irregular, as is the case with most antimony deposits. Their thickness is most 

often from one-half to 2 ern. In tlwm the stibnite is associated intimately with quartz and mispickel, and 

sometimes thl' stibnite and sometimes tlw quart11 predominates. 

The antimony-bearing granulite at Montignat is of a special type that I have frequently had occasion to 

observe in the neighborhood of the antimony vPins in the northern part of the Central Platl'atL * * * In 

reality it is a granular pegmatite (composed of quart11 and generally altered fPldspar without muscovite) in 

which pyrite frequently occurs, if not at Montignat at least in other dPposits. 

The Carolina tin belt a has a length of about 35 miles in Korth and South Carolina. In this belt sedimentary rocks of undetermined age, induding shales, limestones, and sandstones, have been intensely metamorphosed and contorted. These 

sediments have been invaded at several times by igneous intrusions. Comparatively 

large masses of basic dioritic or gabbrolitic rock were intruded. Biotite granite is 

also among the igneous rocks, and numerous dikes of pegmatite cut both the metamorphosed basic intrusion and the sediments. The pegmatite is of chief interest in 

connection with the tin deposits, for in intimate association with some of it the ore 

is found. The tin belt is limited to the occurrence of pegmatite. 

The pegmatite masses are irregular in shape. Forking or branching is rather 

common, and frequently a dike pinches out completely. There are two varieties of 

the rock. One is composed of quartz; and microcline and carries no tin; the tinbearing variety contains abundant muscovite. These rocks are undoubtedly of 

igneous origin and have exerted some contact metamorphic influence upon the 

intruded wall rock. The tin in these dikes is in the form of cassiterite, and from all 

obtainable evidence it seems probable that the cassiterite is an original constituent, 

like the quartz and feldspar. 

Granitic dikes older than the pegmatite and closely associated with it carry 

tourmaline, and quartz veins, also rich in tourmaline, occur near the pegmatite 

dikes. 

G. 0. Smith b has described molybdenum ore of economic value occurring in 

pegmatite in Maine. Molybdenite occurs both in pegmatite dikes and in the granite 

cut by these dikes. The mineral is found in hunches or crystals 1 or 2 inches in 

diameter and is intimately mixed with the quartz and feldspar of the pegmatite. 

Molybdenite occurs at several other localities in Maine, as well as in other New 

England States. The pegmatite dikes are apparently contemporaneous with the 

granite intrusion and represent the latest crystalliz;ation of the granitic magma. In 

the pegmatitic magma molybdenum disulphide appears to have been a prominent 

constituent and to have crystallized early in the consolidation of the dikes. 

a L. C. Graton, Bull. U.S. Geo!. Survey No. 260, p. 188. 

b BulL U.S. Geol. Survey No. 260, 1905, pp. 197-198. 
142 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

PRESENCE OF GOLD IN J\IAGl\IATIC QUARTZ YEINS WHICH ARE 

DEPENDENT UPON GRANITIC IN'I'RUSIONS. 

The writer believes that of all the metals segregated or concentrated into certain 

places during the crystallization of the ultra-silicious phases of granitic intrusions 

gold has the most economic importance. The presence of gold in granites, pegmatites, and aplites has frequently been noted ;a but the chief place in which the gold 

has been found to be segregated is not so rnuch in these rocks as in the closely-related 

quartz veins, which show by their relations and general characteristics a magmatic 

ongm. These veins have been deposited by aqueous magmas which were in various 

stages of dilution by waters and varied from the aqueous yet probably viscous 

silicious magma which has deposited quartz lenses corresponding in age to the intergranular quartz of granites and alaskites to the thinner residual solutions or magmas 

containing more water and less dissolved material, but none the less being truly 

magmatic in respect to the water, associated gases, and dissolved substances. 

EUROPE. 

On the island of Bommel, in Norway, the chief country rock is "gabbro," in 

which large dikes oi "quartz porphyry," passing into granite, and of altered diorite, 

occur. South of this district is a large tract of slate in which are nonauriferous 

quartz veins. The "quartz porphyry" dikes and those of diorite contain strong 

gold quartz veins, whose general contemporaneity with the period of igneous intnsion 

is shown by their being older than some dikes and younger than others. b 

According to De Launay the gold at this place is associated with the granite.c 

Professor Vogtd describes certain veins in Telemarken, Norway, which contain 

chalcopyrite, bornite, and chalcocite, also a little native silver and gold, with a gangue 

of fluorite, tourmaline, apatite, muscovite, and caleite. These veins are considered to 

be genetically connected with the granite in which they appear. This is a normal 

biotite-granite with orthoclase, microcline, and oligoclase, and no muscovite. Near 

the veins the granite is altered to muscovite, quartz, and calcite, with a little chalcocite, fluorite, and chalcopyrite or bornite. 

In the neighborhood of Beresovsk, in the Ural Mounta~n8, are granites which 

contain disseminated free gold tha~ has been held to be originaJ.e l\ ear these 

granites are quartz-feldspar-muscovite rocks, which have been called beresite. The 

peculiar structure and composition of this rock is analogous to that of similar rocks 

in the Kevada mineral districts, as is specially pointed out by the writer for the 

di:.trict of Belmont./ The Russian beresite is regarded by the miners as the surest 

index t~ gold, and native gold occuril within the rock itself. This gold has been 

held to be an original constituent. 

a More rarely free gold ha• been noted in basic rocko. See W. II. Weed, Eng. and Min. Journal, M~trch 31, 1904; M. L. De 

Launay,. Contributioi it !'etude des gites mctalliferes, Paris, 1897, pp. 109-110; J. E. Spun, Trans. Am. Inst. Min. Eng., vol. 

33, p. 321. 

• b Phillips and L<Juis, O"e-Deposits, 2d ed., p. 519. 

c Contribution a !'etude des gites metalliferes, Paris, 1897, p. 111. 

d Zeitschrift fiir pmkt. Geologie, 1897, p. 144; eitcd by lV. Lindgren, Trans. Am. Inst. Min. Eng., vol. 30, p. 643. 

c Beck, Richard, Lehre von Erzlagerstatten, p. 324. 

! Spurr, J. E., Am. Jour. Sci., vol. 10, Nov. 1900, p. 356. 
GOLD lN MAGMATIC QUARTZ VELNts. 143 

H. L. Barvir a in 1903 discussed the origin of the gold in certain parts of Bohemia. 

South of Prague lies the city of Eule, in whose neighborhood gold has been obtained 

since prehistoric times. East of the city are granites intrusive into schists. In the 

schists there are also abundant dikes, which are chiefly schistose greenstones and 

schistose porphyries. The granite contact has the same direction as the gold-quartz 

veins and many of the igneous dikes. The minerals in the gold-quartz veins of the 

district arc quartz, calcite, dolomite, chlorite, some orthoclase, pyr:ite, arsenopyrite, and native gold, with occasional chalcopyrite and molybdenite. In other 

fissure fillings are iron-alumina garnet, epidote, albite, laumonite, stilbite, natrolite, 

and analcite. 

Frorli the extended studies of the author and his pupils concerning the connection and the geological 

signiflcance of tho different rocks of the gold district, it is evident that the gold in southwestern Bohemia is 

connected pr-incipaUy with the granite mass1j of Little Bohemia, with its magmatic differentiation products and its 

minor phases. In part it was a primary constituent of the granite; in part it has bern deposited from the hot 

springs during the intrusions, and finally it has been leached out from the already cor;solidated rocks by means 

of these same hot springs. Gold-bearing veins filling flssures due to atmospheric agencies are very subordinate. 

AFRICA. 

In the Transvaal, South Africa, the gold is sometimes associated with granite 

and diorite. Phillips and Louisb observe that in the De Kapp district the rocks, 

"both stratified and granitic, are traversed by dikes of diorite and pegmatite. * * * 

In the neighborhood of the granite these rocks occasionally carry small ferruginous 

intercalated deposits which are generally auriferous. * * *" 

De Launay c mentions two other districts in the Transvaal where the ores are 

genetically connected with silicious igneous rocks and are related to a group of tin 

veins. 

}1. A. Lacroix,a writing of the gold deposits in Madagascar, concludes: 

Sovf,ml observatione made in othPr regions, notably the demonstration of the existence of free gold along 

the cleavage planes of the granulitized mica schists near Nantes ·and in the tin veins of Limousin,e lead me to 

the conclusion that the gold has been formed in Madagascar by the emanations of the granitic magma, which 

has so profoundly impregnated the crystalline schists of the island. 

De Launayf observes that certain auriferous earths in .Madagascar are probably 

the result of the decomposition of diorites under conditions similaF to those in Guiana. 

AUSTRALIA. 

The gold deposits of eastern Australia are among the most important in the 

world. In the province of Victoria, in the districts of Dargo and Omeo, Howitt g has 

shown (1887-88) that many of the quartz veins are of direct magmatic origin, corresponding to the quartz crystallized in the last stage of the consolidation of granite. -~----~--- ---~--~-----···--~---.. -- ~--~---

a Betra.chtungen iiber den Urs,prung des Go Ides bei Eule und an einigen anderen ~tellcn in Bohmen. Archiv liirnaturw. 

Durchforschung von Bohmen, XII, No.1, Prag, 1901, 98 p. Abstract in Neues Jahrbuch fiir Mineralogic, 1903, vol. 1, p. 440. 

b Ore Deposits, pp. 734--735. 

c Contribution a !'etude des gites metalliferes, Pari•, 1897, pp. 111-112. 

d Cited by J. E. Spurr in Native gold original in metamorphic gneisses: Eng. and Min. Jo...-., Feb. 4, 1904. 

e These localities are in France. (J. E. S.) 

I Contribution a I' etude des gites metalliferes. Paris, 1897, p. 110. 

g Seep. 134. 
144 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

He also pointed out the close relation of many of the auriferous quartz veins to the 

contact of granitic rocks intrusive into Paleozoic sediments. He did not, however, 

suggest that these auriferous quartz veins had a magmatic origin. 

In 1872 Mr. Richard Daintree" drew attention to the fact that the auriferous 

deposits in the province of Queensland, eastern Australia, are entirely confined to 

those districts which are penetrated by certain eruptive rocks, principally pyritiferous 

diorite. The pyrite in these diorites was shown to be occasionally distinctly auriferous and to have produced gold in paying- quantities by its decomposition. Subsequently Mr. Daintree learned from geologists in New South Wales and Victoria 

details to show that the auriferous deposits of these provinces have the same genetic 

relations. Some of the most important auriferous veins were regarded by Mr. 

Daintree as the "result of hydrothermal agencies which preceded and accompanied 

the protrusion and which in some cases continued long after the igneous rock had 

cooled down." 

From the book of Phillips and Louis b the following is quoted: 

Daintrec, Hacket, Wilkinson, and others have shown that a large portion of the gold in Victoria and 

Queensland is due to the agency of intrusive dikes of felstonc, clvan, and diorite, so that reefs of quartz in 

Silurian rocks arc not, as was at one time supposed, the exclusive source of Australian gold. 

At Timharra gold is found in granite. These gold 'fields eonsist of a granitic table-land, traversed by dikes 

of enritec and pPgm,-ctite; also occasionally showing veins of auriferous quartz, which may possibly be segregation deposits.d The weathered granite is sluiced, and very fine gold, to the extent at times of fj pennyweights 

to the ton is obtained. Gold has been found to occur here in unaltered granite and in eurite,d as well as in the 

·decomposed granitP. 

In 1905 Mr. Waldemar Lindgrene described the gold quartz veins of Victoria. 

In the western gold fields of Victoria slates and sandstones are intruded by large 

masses of granitic rock. Aplitic dikes cut the slates at the contacts, which are 

marked by narrow aureoles of contact metamorphism. The granite rarely contains 

quartz veins. 

The vein filling is almost always a massiw, milk-white and sometimes glassy quartz, containing gold and 

a small percentage ol' sulphides, chiefly pyrite and arsenopyrite, but also a little galena, zinc blende, molybcnite, 

and stibnite; fluorite and tellurides seem to be absent. Barite is rare. * * * 

The intrusion of the granitic rocks followed the plication of the slates and preceded the Devonian sedimentation. Consequently tho gra.nitie intrusion and the formation of the quartz veins were closely associated 

events. Field evidence shows that tlw quartz \'eins are later than the granite and the attendant aplitic dikes. 

Mr. Lindgren offers the hypothesis thatthE' gold and the quartz ii1 this type of veins have hcen deposited chiefly by "eruptive after-effects;" in other 

words, chiefly by hot ascending waters originally contained in the granitic magma and released from it by 

decreasing pressure, due to its irruption into the upper parts of the lithosphere. It is quite possihle that atmospheric waters may have played a certain part by aiding the precipitation and by efiecting certain forms of 

concentration in the deposits. 

Albite occurs in the Victoria gold quartz veins, as at Bendigo/ 

In New England, in the northeastern part of the province of New South Wales, 

according to E. C. Andrews,9 there have been two periods of granitic intrusion, one 

of Carboniferous age and one post-Paleozoic (and pre-Mesozoic). There appears to 

a Phillips and Louis, Ore Deposits, pp. 641-642. 

b Ore Deposits, p. 659. 

c "Alaskite." (J. E. S.) 

d The italics are mine. (J. E. S.) 

e Eng. and Min. Jour., March 9, 1905. 

f Lindgren, W., Economic Geology, vol. 1, No.2, p. 163. 

g Records Geol. Survey N. S. Wales, 1905, vol. 7, pt. 1, pp.108-152. 
GOLD IN MAGMATIC QUARTZ VEINS. 145 

be no genetic connection between the first period of igneous activity and ore deposits; 

but with the rocks of the later period, especially the siliceous phases, ores are closely 

connected, occurring near the periphery of the granite bodies. These ores are 

divided into three classes: (1) Segregations from cooling acid magmas, containing 

as valuable components chiefly cassiterite, wolfram, and bismuth; (2) magmatic 

segregations, slightly later and originally more aqueous than those first named, containing as valuable components cassiterite, bismuth, molybdenite, and probaply 

silver-lead and zinc ores; (3) ores formed by aqueous secretions from dikes which 

were more basic than those mentioned above and which were injected after the consolidation of the more acid magma. The valuable components of the ores of this 

class are gold, silver, copper, lead, antimony, scheelite, and zinc. 

In western Australia, in the district of Coolgardie, according to M. Gascuel, 

as cited by De Launay,a -the gold-quartz veins are present almost exclusively 

in greenstones (diorites and diabases), which are decomposed into red clay at the 

surface. 

A specimen from the Mount Monger mine, in northeast Coolgardie, described by 

Mr. A. Sehvyn-Brown,b weighs 100 ounces and consists of 85 per cent gold, the balance being ferruginous quartz and tourmaline. The tourmaline crystals are thickly 

studded in the solid gold and sparingly in the quartz. The country rock is largely 

granitic, and quartz veins, mostly auriferous, are numerous. These veins always 

carry pyrite, and occasionally tellurium has been detected. Both tourmaline and 

gold occur in the massive granite. 

ASIA. 

In China the reported gold-quartz veins occur almost entirely in granite, as at 

Ninghai, the Chao-Yuen district, and Yeshui, in Mongolia.c 

The writer is verbally informed by Mr. Bailey Willis that according to his information from Mr. G. B. Wilson, engineer in charge, the mines of Kushantsi, near 

Jeho, in Mongolia, are in granite and diorite. 

In Siberia the connection of gold with granite and granulite has been observed 

in more than one place, especially by M. Levat in the Trans-Baikal region, southeast 

of Irkutsk. According to M. Levat the gold is contained in aplite, which is connected with granite masses. In another locality, on the Zeya River, a northern 

tributary of the Amoor, M. Levat believed the gold to have a direct genetic relation 

to intrusive granites. a 

SOUTH AMERICA. 

BRAZIL. 

The gold deposits of Brazil, especially in the province of Minas Geraes, are of 

considerable interest. In this district, at Candonga, according toW. J. Henwood,e 

a Contribution a !'etude des gites metalliferes, Paris, 1897, p. 109. 

b Eng. and Min. Jour., Dec. 9, 1905, p. 1062. 

c Phillips and Louis, Ore Deposits, p. 618. 

d Levat, E. D., L'or en Siberie Orten tale, Paris, 1897: cited by M. L. Do Launay, Contribution a !'etude des gites metaliferes, Paris, 1897, p. 111, and by C. W. Purington, Eng. and Min. Jour., 1905, p. 71. 

eHenwood, W, J., Observations on metalliferous deposits, Trans. Roy. Soc. Cornwall, vol. 8, pt. 1, 1871, pp. 175-176, 

311, 320. 

13002--~o. 55--06----10 
/~i 

146 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

the granite contains particles of free gold sparingly mixed with quartz, feldspar, and 

iron ore, just as tin ore is sprinkled in the granite of Cornwall. a 

Concerning the ore deposits of the region, Henwood writes: 

Although the metalliferous depo~its are more quartzose and contain a larger proportion of iron ore than 

the rock, they partake of its granitic character. Through this ferruginous granite gold is always thinly scattered b 

alloyed, however, with from 5 to 8 per cent of palladium, c and of a yellow as pale as that assumed occasionally 

by native silver.d It forms sometimes a model, sometimes a mold for other minerals, and thus embrds in some 

pl:tces the sanie ingredients which embed it in others. e Gold in rough crystals/ often studs the sides of drusy 

cavities; and in minute spheroids, seldom more than from 0.012 to 0.022 of an inch in diameter, it is sometimes 

scantily disseminated through other pa.rts of the formations. 

Their more quartzose portions inclose nests of earthy brown iron ore and small octahedral crystals of pure 

bright yellow gold.g * * * 

The auriferous repositories are bounded by joints of one series: but barren matter within joints of different 

range sometimes interrupt them;'< in both, however, as in the adjoining roPks, the prevalent ingredients are 

granitic. i * * * 

The only auriferous granite in Minas Geraes consists of a yellowish feldspar, white quartz, and oxydulated 

iron ore, i irregularly mixed, however, with crystalline granules of gold, which alloyed with from 0.05 to 0.08 

its weight of palladiumk and som('times inclosing, but more frequently embedded in the other ingredients, thus 

forms an integral part of the rock. l 

In 1887, De Launaymnoted that the group of auriferous mispickel veins, such as 

those at Passagem and at Faria, in Brazil, probably belong to the family of tin veins 

and are connected with siliceous igneous rocks. He noted that at Passagem the 

veins contain tourmaline, bismuth, and pyrrhotite. 

E. Russak, in 1898,n described the gold-bearing quartz veins of Passagem, in the 

State of Minas Geraes, in Brazil. The Passagem gold mine lies 7 kilometers east of 

Ouro Preto, the capital of the State of Minas Geraes, and, together with Morro Velho, 

s one of the most important Brazilian gold mines. The vein consists chiefly of 

white quartz, tourmaline, and arsenopyrite, with subordinate amounts of pyrite and 

pyrrhotite. It really forms a series of leaves which are alternately narrowed and 

enlarged and are alternately rich and poor in gold, so that the thickness of the vein 

varies between 2 and 15 meters. The largest lenses are filled with schistose quartzite 

and metallic quartz poor in gold. The portions which consist of pure, finely crystalized arsenopyrite and black tourmaline are the richest. With the accession of quartz 

a ''Three miles southeast of Two-bridges" on Dartmoor, "where some tin mines are worked, that metal is found disseminated in the granite as one of its integral parts." Berger, Geological Transactions, vol. 1, p. 120. 

b Captain Herbert, Asiatic Researcbes, vo!. 1, 1829, p. 23(}. Ante, pp. 3, 46, Notes. 

c Johnson, Percival Norton, F.R.S., F. G. S.,etc., MSS. Also W. J. Cock, On palladium, London, Edinburgh, and Dublin 

Phil. Mag., 3d Ser., vol. 23. 1843, p. 16. 

d Levy, Description d'une collection de mineraux formec par M. Henri Reuland, vol. 2, pp. 320-328. 

e Carne, Cornwall Geol. Trans., vol. 4, p. 100. 

t Mohs, Mineralogy (translated by Haidinger), vol. 2, p. 437. Levy, Description d'une collection de mineraux, vo!. 2, 

p.313. 

g Lott, Edward W., Commissioner of Candonga, 1844, MSS. 

h Helmreichen, H. V. von, 1844, MSS. , 

i Cornwall Goo!. Trans., vo!. 5, Tables XIII, XVI, XLIII, L, XC. 

j Ante, p. 175. 

k Ante, p. 176. 

l Berger, Geol. Trans., vol. 1, p. 120. De Luc, Geological Travels, vo!. 3, p. 342, Herbert, Asiatic Researches, vol. 1, 

p. 236. Sedgwick, Phil. Mag. and Annals, vol. 9, 1831, p. 283. Henwood, Cornwall Geol. Trans., vol. 5, pp. 15, 53, 73, 119,235. 

Murchison, Geology of Russia in Europe, vol. 1, p. 483. Ante, pp. 46, 175. 

m Contribution It !'etude des gites metalliferes, Paris, 1897, p. 111. 

n The gold-bearing quartz veins of Passagem in Minas Geraes, Brazil. Zeitschrift fiir praktische Geologie, Oct., 1898, 

p. 345. 
GOLD IN MAGMATIC QUARTZ VEINS. 147 

the ore grows poorer. On rich hand specimens gold can be seen with the naked eye 

in granules or crystals grown upon arsenopyrite or tourmaline. 

The following minerals were found: Gold, arsenopyrite, pyrite, pyrrhotite 

(copper pyrite), galena and stibnite (according to Ferrand), quartz, oligoclase-albite, 

muscovite, green' chrome-bearing muscovite (fuchsite), zircon, monazite, xenotime, 

magnetite, rutile, biotite, tourmaline, andalusite, staurolite, hercynite, garnet, disthene, cummingtonite, calcite, dolomite (according to Ferrand), siderite and ilmenite. 

Doctor Russak divides these into the following groups: 

1. Vein minerals: Quartz, arsenopyrite, pyrite, copper pyrite, pyrrhotite, galena, 

stibnite, gold (with bismuth), calcite, dolomite, siderite, and ilmenite, of which the 

last named, including the gold, are apparently secondary infiltrations and later 

formations. 

2. Granite minerals: Quartz, muscovite, biotite, oligoclase-albite, zircon, monazite, xenotime, perhaps also amphibole, magnetite, and rutile. 

3. Contact minerals: Tourmaline, andalusite, staurolite, disthene, garnet, hercynite, cummingtonite, and also, certainly in part, biotite. 

In the quartz vein tourmaline plays the chief r6le as the accompaniment of the 

minerals. In the portions of the vein which have a granitic structure, the tourmaline 

and quartz aggregates have a great similarity to the luxullianite of Cornwall. The 

tourmaline and quartz portions of the Passagem vein pass by gradual transition to 

pure arsenopyrite. 

Doctor Hussak concludes (p. 356) that the quartz vein is of intrusive nature, an 

ultra-acid granitic apophysis. In favor of this interpretation is the near occurrence 

of a granite massif, about 1 kilometer away in air line, and the certainly proved occurrence of occasional minerals which are thoroughly characteristic of granitic rocks, 

such as zircon, monazite, and xenotime, in angular crystals. The occurrence of a 

feldspar near albite in a quartz vein seems also to favor a granitic origin. Albite is 

known to be a very frequent component of pegmatitic granite veins. This eruptive 

quartz vein broke through the quartz schists, shattered them, and in part absorbed 

them, and formed against the hanging wall and against the foot wall a definite contact 

zone characterized by the minerals already mentioned. The native gold is doubtless 

a secondary infiltration precipitated from solutions, as well as the calcite. The pyrite, 

pyrrhotite, and arsenopyrite are considered to have the same origin as the quartz. 

Similar quartz veins, only a few meters thick, break through the mica schist at many 

points in Minas Geraes and Goyaz. These carry gold and are relatively rich in splendidly formed monazite crystals. 

In 1899 0. A. Derbya discussed the origin of a layer of argillaceous material in 

fine-grained quartzite in the region of Diamantina, Minas Geraes, Brazil. The argillaceous material, which consists of quartz and kaolin, and can hardly be else than a 

rock of original granitic or pegmatitic type, to judge from the character of its contact 

must have been eruptive. Macroscopic accessory elements are rutile and specular 

iron. By washing, a heavy residue, consisting of anatase, magnetite, tourmaline, and 

xenotime is obtained. The last-named mineral is the most .significant, as it is only 

a On the association of argillaceous rocks with quartz veins in the region of Diamantina, Brazil: Am. Jour. Sci., 4th ser., 

vol. 7, 1899, pp. 343-356. 
148 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

known in situ in Brazil as an extremely constant and characteristic accessory of the 

ultra-acid (muscovite) granites and pegmatites. 

The observations above recorded indicate the presence in the older series of the region of dikes of a rock 

characterized by titanium minerals and monazite as primary accessories that have been sheared and metamorphosed together with the rocks into which they were injected, and that the schistose and presumably weak 

layers thus produced have more frequently than others been the seat of subsequent injections of pegmatitic 

material that passes to pure quartz. * * * 

In 1904, Mr. Derby a confirmed the statement made by him many years before b 

that in the districts of Campanha and Sao Gon~alo, gold occurs in gneiss. This 

gneiss has the characteristics of a sheared granite, and the gold is in crystalline form. 

The residue from crushed samples of this rock is chiefly of zircon, with some magnetite 

and ilmenite. The amount of gold in the specimens examined was 5 to 10 grams 

per metric ton. This mode of occurrence, independent of sulphides, and more or less 

independent of quartz veins, seems to predominate throughout the district. 

Under the heading "Gold in granitic apophyses," Mr. Derby described certain 

vmns: 

These having tht> appearance of ordinary quartz veins are characterized by included patches of k>wlinized 

feldspar or of mica, carrying one or more of the rharacteristie granitic accessories-zircon, monazite, and xenotime-and are evidently extreme phases of granitic (pegmatitic) dikes and stringers. Throughout the Diamantina district it is rare to see an outcrop of these veins which does not show signs of having been worked or at 

least prospected for gold. The only one examined that is certainly gold-bearing was close to the gr<>at diamond working of Sao Joao da Chapada, in which a fine example of the quartz-kaolin type is presented. This 

cuts a somewhat sheared diabase and consists of vein quartz of the ordinary aspect, with partings and patches 

of green muscovite, which givt• an abundant residue of rutile and monazite. A lode which has been quite 

extensively worked at Bandeirinha, about 20 miles to the southward, is believed to be of this character, since 

the concentrated sand gives an abundance of beautifully fresh monazite of the peculiar prismatic type described 

in the above-mentioned paper. 

The great mine of Morro V clho, in the Sahara district of Minas Geraes, is of this charader, ae are also the 

adjacent mine of Raposos and that of Cuyaba (at least as regards its main lode), about 10 miles distant. The 

sulphides are pyrite, pyrrhotite, arsenopyrite, and chalcopyrite-zinc blendc and galena occurring only as great 

rarities. The gangue is a finely granular mixture of carbonates of iron, magnesia, and lime (siderite, dolomite, 

and calcite, apparently in this order of abundance), with quartz and apparently also a feldspar, albite, which 

in the mass of the ore is distinguishable with difficulty from the quartz, but appears in great perfection and 

beauty in the vugs. Typical vein-q11art' occurs only in subordinate amounts and local developments. * * * 

A singular feature now appearing in one part of the Cuyaba lode is a considerable mass of a coarse-grained 

greenish rock of granite texture, composed essPntially of plagioclase feldspar thickly sprinkled with arsenopyrite and showing irregular fracture zones filled with green chlorite. This mass, which carries a little zinc blende, 

occurs in the width of the better ore, with which it appears to have a genetic connection. This also recalls a 

feature of the Passagern lode. 

Feldspar, in the form of beautiful crystals of albite, is common in the vug linings at Morro Velho and is 

evidently a constituent of the g:angue as well, though owing to the fineness of the grain and the absence of 

observable twinning it is distinguishable with difficulty from the quartz. 

L. Ferraz,c describing the Palma gold deposits in the State of Minas Geraes, 

Brazil, writes that the field is characterized by the crystalline character of the rocks, 

gneiss predominating with granites and syenite. 

The granites, some typical, some with amphibolite, pyroxene, and garnet, form a series tending toward a 

true syenite. VPins of granulitic black tourmalines in prisms of various sizes, separate or agglomerated, and 

veins of pegmatite, common or of graphic structure, cut into the primitive masses. 

a Notes on Brazilian gold ores: Trans. Am. Inst. Min. Eng., vol. 33, pp. 282-287. 

bAm. Jour. Sci., 3d ser., vol. 28, 1884, p. 443. 

c The Palma gold deposit of Minas Geraes, Brazil: Min. and Sci. Press, March 19, 1904, p. 199. 
GOLD IN MAGMATIC QUARTZ VEINS. 14~ 

Two distinct types of rock occur-the miascitic, rich in black mica and ilmenite; and the zirconian, eontaiEing a certain proportion of zircon and monazite. 

Among the residuary minerals found in the pan concentrates are the following: Sphene or titanite, rutile, 

garnets, black tourmalines, graphite, zircon, oligist (hematite), magnetite, disthcnite, staurolite, and monazite. 

Gold is found in a statP of great purity, as flakes, grains, and small nuggets, in alluvial gravel's which cover 

the river beds and the area subject to floods, as well as thP country surrounding the headwaters of thl' streams 

previously detailed. The pan concentrates consist mainly of quartz grains, titaniferous minerals-such as 

ilmenite, titanite, and rutile-almandine and pyrope garnets and melanite, black tourmaline and monazite. 

Oligist (hematite) and magnetite occur in diminished proportion. Wherever the gravel be panned, more or 

less gold is found. 

CHILE. 

In Chile, De Launay a notes the existence of gold in granite, together with cassiterite, copper pyrite, compounds of bismuth, tellurium, selenium, etc. The statement 

is made b that the gold in many granites on the coast range in Chile is of primary 

origin. 

GUIA~A. 

In British Guiana Phillipf> and I~ouis c state that gold-quartz veins occur mostly 

in metamorphic schists and gneiss, and nearly all the streams and rivers that traverse 

regions occupied by the above rocks or by granite are gold-bearing. 

At the Omai placer mine, on the Essequibo River, in British Guiana, according to 

E. E. Lungwitz,a a dike of aplite contains quartz and feldspar, the latter largely 

plagioclase. Gold occurs in it in fine dust and coarse nuggets, and is accompanied by 

quartz. The aplite has been tested to a depth of ROO feet. It contains $1 to $15 per 

ton in gold. It also contains pyrite, sericite, epidote, zoisite, and carbonates. 

Mr. J. B. Harrison," government geologist, regards the gold as not an original 

constituent of the aplite, but as having been brought into it by percolating waters, 

and that it was in part derived from the degradation of an overlying diabase d1ke. 

Messrs. Harrison and Perkins! state their belief that the siliceous rocks of the 

district, whether gneiss, granite, or porphyry, do not appear to have been the 

original sources of practically any of the gold of the auriferous gravels, which have 

probably all been derived from the basic rocks, either the diorite or the diabase, "or 

from parts of the acidic rocks impregnated with the metal by percolating water 

durmg their intrusions. The parts of the diabase rocks which are the richer in iron 

ores and especially in pyrites are also the richer in content of gold." 

E. E. Lungwitz g is also of the opinion that the origin of the gold in British 

Guiana stands in the closest connection with the diabase. He writes: 

There is no gold district in Guiana without diabase, and the richest portions of the Guiana gravels are 

characterized by the fact that the fissures in their nPighborhood which have been filled by diabase have been 

again occupied later on by aplite or diabase intrusions. The result of this was a thorough shattering of tiw 

hanging and foot walls of these dikes, the filling of the adjacent fissnrPs by quartz, and enrichment of the 

a Contnbution a 1'6tude des gites m6tallifBrcs, Paris, 1897, p. 111. 

b Beck, Richard, Lehre von Erzlagerstatten, Berlin, 1901, p. 19, on the authority of II. Schultze. 

cOre Deposits, 2d ed., p. 188. 

d Zeitschr. fiir prakt. geologie, July, 1900, p. 217. See also W. II. Weed, Eng. and Min. Jour., March 17,1904, p. 440. 

e Cited by W. H. Weed, Eng. and Min. Jour., March 17, 1904, p. 440. 

f Report on the geology of the Esseqmbo, Potaro, Konawaruk, and Demerara rivers, Georgetown, Demerara, 1900, 

p. 69. 

g Zeitschrift fiir praktische geologie, July, 1900, p. 217. 
150 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

sal bands by gold ores. The size of the veins is variable, but according to my experience hardly ever as much 

as 3 feet. On the ot,her hand, the number of small quartz Yeins is so great that in many places the aplito 

goes over into so"called beresite-for example, at Omai and Potaro. The age of these secondarv fissures is 

very different, as appears from their intersection and their characteristic vein filling. In most cases the gold 

is associated with cupriferons iron pyrites, more rarely arsenopyrite, and in some small veins (Omai) with 

scheelite. I wish to call attention especially to the last-named case, since it is one of the few occurrences 

where gold appears associated with wolfram minerals. 

While recognizing the accuracy of the descriptions of the British Guiana gold 

ores given by the above-named geologists, and the fact that the gold is associated 

with basic dikes, certain features seem to the writer to indicate that the conception of 

the origin of the gold has not been made broad enough to include the bearing of all 

the associated facts. The presence of eruptive granites and of aplite dikes, frequently 

auriferous, and especially the association of gold with tungsten and mispickel, are significant features, which must be considered. Tungsten is an element frequent in tin 

deposits,a is one of the most characteristic elements in pegmatite, and, like tin and 

molybdenum, seldom occurs in notable amounts except in pegmatites and granitic 

rocks.b Arsenopyrite is also frequently found in pegmatites and veins of the tin 

group, and, as above noted (p. 146), De Launay c has stated his belief that the auriferous mispickels belong to the family of tin veins. It thus appears possible that in 

British Guiana the deposition of the gold ores represents one of the closing phases of 

the great granitic intrusions, and that the basic dike rocks, with which the gold ores 

are associated, as well as the siliceous dike rocks in connection with which they are 

also frequently found, are representatives of the general process of granitic injection, 

earlier than the veins, while still subsequent to the main intrusion. A similar group 

of phenomena, attendant upon a great granitic injection, beginning with the main 

intrusion of granite and followed by the diorite and diabase (usually altered to greenstone) dikes, the ultrasiliceous (aplite, pegmatite, eurite, or alaskite) dikes, and the 

auriferous quartz veins which usually represent the last stage of all, can be recognized or suspected from the previous descriptions in many important auriferous districts, such as those of Australia, Madagascar, etc. A similar group of phenomena 

has been studied by the writer in the Silver Peak district. 

After the above was written and in proof the writer has seen a later report by 

Mr. J. B. Harrison on the petrography of the Cuyuni and Mazaruni districts, British 

Guiana, and of the rocks at Omai, Ess~cquibo River.d The rocks of the districts are 

described in detail. They consist of siliceous gneisses which are granites and granitic 

rocks altered by shearing, and which are intruded by numerous pegmatite veins, 

which in places are highly feldspathic; in other places consist almost entirely of quartz. 

Garnet, beryl, and apatite occur in these pegmatites. Assays of the gneisses show 

the presence of gold in all, at the rate of a few grains per ton. These granitic 

gneisses are traversed by basic gneisses and schists, which represent sheared basic 

intrusives in the granitic rocks. Assays of these rocks show the presence of gold in 

all, in quantity about the same as in the older granitic rocks. "The gold accoma For example, the tin deposits of Mount Bischoff in Tasmania, described by W. von Fircks, Zeitsch. deutsch Geol. Ges. 

Ed. 51, p. 433, 1899; cited by W. Lindgren, Trans. Am. Inst. Min. Eng., vol. 30, p. 623. See also J. II. L. Vogt, Zeitsch. fiir 

prakt. Geol., July, 1898, p. 238. 

b Kemp, J. F., Ore deposits of the United States and Canada, 3d ed., p. 37. 

c Contribution a !'etude des gites metalliferes, Paris, 1897, p. 111. 

d Report on the petrography of the Cuyuni and Mazaruni districts, etc., Georgetown, Demerara, 1905. 
GOLD lN MAGMATIC QUARTZ VEINS. 151 

panies in part the heavy metals of the01e metamorphosed rocks; but some of it is 

present in the numerous tongues and veinlets of quartz which traverse them, filling 

cracks and spaces between or crossing their folia." a Other igneous rocks of the 

district, in part schistose, in part massive, may be classed in general as porphyries 

of varying composition. The schistose facies were found by assay to contain small 

quantities of gold. Granitic rocks are also described, more or less gneissose. They 

include aplite and granite, which pass locally into quartz-diorite and diorite. 

Syenite and gabbro also occur. All these rocks yielded gold on assay. Diabase 

also occurs. 

Following are part of Mr. Harrison's general observations as to the source of 

the gold :b 

The comparatively few dikes of diabase which are noticeable in the district apparently indicate that in it 

the diabase, which may be :egarded as the main source of gold in the central district of the colony, plays 

only a subordinate part as a source of supply. The rnsults of the assays given in this report indicate that 

gold is present in more or less minute amounts in all of the country rocks of the district, and that the proportions found in the basic rocb arf', on the whole, only a little higher than those in the acidic ones. 

Concerning the derivation of the gold at the Omai mine, referred to above, Mr. 

Harrison remarks: 

While the country at Omai is in accordance with that of the district generally, it differs from it in one 

very important respect-the epidiorites and chlorite schists, which are the country rocks, have been intruded 

by a mass of aplitic granite which appears to be the main source of the gold at Omai. 

Although Mr. Harrison still believes that the basic rocks of these districts were 

originally the source of the gold, these later observations of his are more in harmony 

with the writer's suggestions above than are his earlier ones; as also is his observation that the gold in the basic rocks occurs in part in numerous veins and veinlets 

of quartz, which traverse the rocks. 0 

De Launay c notes that in French Guiana the gold appears often to be associated 

with diorites, which have decomposed in place to form auriferous earth. He also 

notes that in the contested territory between French Guiana and Brazil, according 

to M. Bernard, the gold is found associated with manganiferous quartz in diorites, 

with veins of granulite. These igneous rocks occur in gneisses and amphibolite 

schist. 

NORTH AMERICA. 

BRITISH AMERICA. 

In the gold-bearing region of Nova Scotia, quartz veins are contained in metamorphosed sedimentary rocks, which are cut by many great intrusions of granite. a 

Dr. A. P. Coleman e has furnished notes on the gold mines of western Ontario. 

After a summer's work in the gold region he remarks: 

Two points have struck me forcibly during the summer-om', the frequency with which truP fissure veins 

bearing free gold have been found in or near masses of eruptive granite which have burst through the Huronian 

schists; the other, that at two points immen8e bodies of schists, impregnated with sulphides-i. e., fahlbandshave prov<>d auriferous, and in one instance a hill of porphyry of great extent shows the same feature. 

a Op. cit., p. 23. 

bOp. cit., p. 51. 

c Contribution a !'etude des gites metallileres, Paris, 1897, pp. 109-110. 

d Kemp, J. F., Ore deposits of the United States, 4th cd., p. 397. 

e Fifth Report Ontario Bureau of Mines, 1895, p. 86. 
152 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

On the Pelly River, in British Columbia (a part of ~he Yukon gold belt), Dr. 

G. M. Dawson a found evidence to show that the development of quartz veins had 

occurred contemporaneously with the upheaval of the granites, and probably by 

some action superinduced by the granite masses themselves while they were still in a 

formative condition. 

In a number of different cases free gold has been described as an original constituent of igneous rocks in British Columbia. In 1894 Ferrierb identified original 

native gold in a perfectly fresh porphyritic syenite from the Kamloops district. 

R. W. Brockc has described a number of similar cases. He has described a goldbearing porphyry dike from the North Fork of the Salmon River, West Kootenai, 

British Columbia. As no sulphides were detected and the rock is quite fresh, the gold 

is probably native and an original constituent.d Of twelve specimens of unaltered 

porphyry dikes from different West Kootenai points collected as rock specimens, but 

submitted for assay, six proved auriferous. An absolutely fresh alkali syeniteporphyry dike in the V alkyr Mountains east of lower Arrow Lake contains coarse 

free gold, visible to the naked eye.e The rock, which was collected as a petrographical specimen, contains several particles of native gold almost as large as pin 

heads. Mr. Brock remarks that the large bodies of copper-gold ore exploited in this 

region occur alongside or near these dikes, with which they appear to be genetically 

connected. 

ALASKA. 

The relation of gold ores to intrusive granitic rocks has been noted also in different parts of Alaska. The writer in 18981 described the occurrence of masses of hornblende granite intrusive into schists and gneisses in the Yukon gold district. There 

is a gradual transition series from this typical granite to a biotite granite, and from 

this by diminution of the biotite into quartz-alkali-feldspar rocks or alaskites. In 

the alaskite series the change continues by relative increase in amount of quartz and 

decrease in feldspar. Finally, by disappearance of the feldspar, the rock becomes 

entirely of quartz. These more siliceous granitic phases are entirely in the form of 

dikes. Quartz veins or dikes in the Yukon district, which probably have this origin, 

contain pyrite, argentiferous galena, and free gold. From them a portion of the 

Yukon placer gold is probably derived. Associated with the siliceous dikes are basic 

dikes, which also pass by transitional phases into the normal granites. The basic 

and siliceous dikes are regarded as complementary, both belonging to the later stages 

of the granitic intrusive phenomena. 

On the Tanana and White rivers, Alaska, Mr. A. H. Brooks g noted at a number 

of places transitions between quartz veins and coarse pegmatites similar to the 

transition noted by the writer in the Yukon district. The veins are abundant in the 

schists of this region, and are composed largely of barren white vitreous quartz, but 

not infrequently contain other minerals. Calcite is a common constituent. Copper, 

iron pyrite, and galena were also observed in the veins. None of the veins found ~~~ ----- --~-~------ --------- -----~~~~~~~--

a Ann. Rept. Geol. and Nat. Hist. Survey Canada, vol. 3, pt. 1, p. 35B. 

b Rept. Geol. Survey Canada, 1894, p. 395B. 

c Eng. and Min. Jour., Mar~h 31, 1904. 

d Jour. Canadian Min. Inst., 1889, p. 84; Geol. Survey Canada, Summary Rept., 1901, p. 64. 

e Summary Rept. Geol. Survey Canada, 1901, p. 64. 

I Eighteenth Ann. Rept. U. S. Geol. Survey, pt. 3, p. 312. 

u Twentieth Ann. Rept. U. S. Geol. Survey, pt. 7, 1900, pp. 484-486 incl. 
GOLD IN MAGMATIC QUARTZ VEINS. 153 

showed tree gold to the naked eye, but assays o£ several specimens showed the presence o£ small quantities o£ both gold and silver. The highest assay showbd .05 

ounce gold and .95 ounce silver to the ton. 

The eastern part o£ the Ketchikan district,a in southern Alaska, is occupied by a 

portion o£ a great intrusive granite mass. The granite is cut by intrusions of various 

rocks, the most common being coarse white pegmatites, which occur in small dikes 

and veins. Diabases and basalts are also not uncommon. 

The granite itself has no econom;c importance, unless possibly somp of it may some time he used for building 

purposes. The distribution of the granitic rocks, however, bas a close relation to ore df•posits, for the mineralization of the adjacent sediments seems to occur more often within the zone affected by the intrusions. An examination of the map of southeastern Alaska and adjacent portions of British Columbia, which shows the location 

of the mining districts, indicates that a certain ('lass of deposits nrc found only in the two zones of metamorphosed 

sediml'nts which flank the granite h8lt. 

In the Cook Inlet region, Alaska, gold is found in aplite dikes, according to Mr. 

'\V. C. Mendenhall,b A sample of one of these aplite dikes given to Mr. Mendenhall 

assayed $7.50 per ton, mostly in gold. 

In the Nome region, Messrs. Schrader and Brooks" report quartz and calcite 

veins containing sulphides cutting metamorphic marble and schists. A large 

area of granite was also reported. Tin also occurs in this region.d In the region 

surrounding the York Mountains limestones and slates, more or less metamorphosed, are cut by large granite masses surrounded by branches which take the form 

o£ porphyritic dikes. The distribution of the granitic intrusives is of the greatest 

economic importance, since many of the known tin lodes occur in the granitic dikes. 

The granite consists of quartz, microcline, and biotite, with accessory albite, muscovite, zircon, apatite, tourmaline, pyrite, and fluorite, and probably cassiterite. The 

main tin vein, situated half a mile from the granite, is a white porphyritic dike, more 

or less altered to greisen. It contains disseminated cassiterite with fluorite, calcite, 

lithia mica, and quartz. Tourmaline, topaz, pyrite, garnet, and galena are also 

present in the vein, and wolframite was found in the float. The siliceous ore sometimes shows spangles o£ free gold. The limestone which forms the wall rock of the 

dike is altered to epidote, garnet, etc. 

UXITED STATES. 

In the Appalachian gold-quartz region are numerous intrusions o£ granitic rocks, 

and pegmatite is abundant.c ~Ir. C. W. Purington/ however, has called attention 

to the fact that in the southern Appa'achians, where gold-bearing quartz veins occur, 

although dikes are almost a constant phenomenon, they are in most cases of a basic 

character, siliceous dikes being exceptional. He refers especially to the Haile gold 

mine, in South Carolina, in which the principal mine workings are below dikes of 

diabase in the hydromica schists.ll 

a Brooks, A. II., Prof. Paper U.S. Gcol. Survey No.1, pp. 4&-47. 

b Twentieth Ann. Rept., U.S. Geol. Survey, pt. 7, p. 321. 

cTrans. Am. lnst. Mm. Eng., vol. 30, p. 238. 

a Collier, Arthur J., Bull. U.S. Geol. Survey No. 229, 1904. 

e Philltps and Louts, Ore Deposits, 2d ed., pp. 786-787. 

fOre deposits: Eng. and Min. Jour., 1905, p. 85. 

g Described also by G. F. Becker, Gold fields of the southern Appalachians: Sixteenth Ann. Rept. U.S. Geol. Survey. 

pt. 3, p. 306. Also ll. B. C. Nttzc and II. A. J. Wilkins, The present condition of gold mining in the southern Appalachian 

States: Trans. Am. Inst. Mm. Eng., vol. 25, p. 767. 
154 ORE DEPOSITS OF SnVER PEAK QUADRANGLE, NEVADA. 

E. C. Eckel,a in describing the gold and pyrite deposits of the Dahlonega district 

in Georgia, writes: 

The writer belie\'es that it can now be rrcceptcd 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. * * * 

The genetic relationships existing between the ore deposits and the igneous rock in the two cases prPsented 

(granite and diorite) are of a very different character. The diorite, as noted earliPr in this paper, was injected 

into the schists at a much earlier period than that during which the orp deposits were formed. * * * The 

fact that many prominent gold-bearing veins occur along the contact between the diorite and the mica schists is 

not due, therefore, to any direct action of the dionte considered as an igneous rock but to the facts (a) that 

fissures are most likely to be formed along the contact between two formations differing in hardness and rigidity, and (h) th>tt }uch fhsur0s, minute. at ti t'8t, may have been enlarged by the solution of tht'. rnhttively 

unstable diorite. · 

VYith regard to those deposits which occur along the contact bctwePn granite and mica schist tlu:> case is 

somewhat different. Here the intrusion of the granite may possibly have some direct g<>rietic connection with 

tht> formation of the ore dcpolits. 

These contradictory observations as to the relative influence of basic and 

siliceous dikes on the formation of gold veins in the Appalachians call up at once the 

similar situation noted above for Guiana and others of the world's gold fields, and we 

may suspect in this case also that the greenstone dikes as well as the siliceous dikes 

arc both phases of great granitic intrusions, while it is most probably true that the 

auriferous veins, if, as seems to be indicated, they are of magmatic origin, are much 

more closely related to the siliceous dikes than to the basic ones. 

Observations upon the magmatic origin and the connection with the intrusive 

granites of auriferous quartz veins in Nevada and California have been made in the 

preceding pages. North of Nevada, in Idaho, Mr. W. Lindgren b divides the gold 

deposits into two distinct classes: 

(1) A pre-J\liocene series, probably of Cretaceous age and most likely formed in 

about the same time as the California and Oregon gold-quartz veins. These deposits 

occur chiefly in the great granite area of the State, which is known to be postCarboniferous and pre-Miocene, and which appears to have been intruded at approximately the same time as the great granite batholiths of California. 

(2) A post-Miocene series occurring in basalt and rhyolite. These veins are of 

the usual propylitic type, and are characterized by containing both silver and gold. 

In Madison County, Mont., gold-quartz veins occur in granite, in Beaverhead 

County at the contact between limestone and granite, in Lewis and Clark County 

in granites and slate.c In the Bitterroot Range and Clearwater Mountains of 

Montana, according to Mr. W. Lindgren,d nearly all the veins occur in granite or 

gneiss, chiefly near the eastern and western margins of the great central granitic 

area, which itself seems to be generally barren of valuable deposits. The granites 

arc intrusive into slates, limestones, greenstones, and gneiss. The veins are auriferous fissure veins, and two chief belts have been distinguished, one containing 

chiefly gold and the other containing copper, lead, and silver as well as gold. 

The following notes in regard to gold ores near Helena have been kindly fura BulL U.S. Geol. Survey No. 213, p. 57 et seq. 

b Trans. Am. Inst. Min. Eng., vol. 30, p. 824. 

c Kemp, Ore Deposits of the United States, 4th ed., p. 320. 

d BulL U.S. Geol. Survey No. 213, 1903, pp. 66, 70. 
GOLD IN MAGMATIC QUARTZ VEINS. 155 

nished to the writer, together with specimens of the rocks and ores, by Mr. W. H. 

Weed. 

About 4 miles south of Helena there is a contact between a great intrusive mass 

of granite or quartz monzonite on the south and intruded sedimentary rocks on the 

north. The date of this intrusion is post-Cretaceous. The rock is a biotite-granite 

or quartz-monzonite, containing tourmaline ncar the borders, not in the main mass. 

Practically all the gold in the Helena region is derived from a belt in the granite 

near the contact and to a less extent in the intruded rocks. A zone following the 

, contact and having a width of 3 miles covers practically all the gold-producing area. 

The general nature of the orcs has not been especially studied. .Mr. vVeed, however, 

has collected specimens and notes from the vVinscott mines, 4 miles south of Helena. 

At this point there lies in the granite an elongated pegmatitic mass which contains 

gold and is mined as ore. There is also gold in the neighboring granite or diorite. 

Specimens of this pegmatitie rock shown to the writer by Mr. Weed are composed macroscopically principally of feldspar, tourmaline, pyrite, and quartz. There 

is a general radiating structure, the tourmaline and feldspar being arranged frequently in sheaves of elongated crystals, while the quartz and pyrite are granular 

and are included in the elongated crystals or are arranged between the sheaves. 

This structure grades to the granular tYJW. A thin section of this rock shows under 

the microscope an apparent allotriomorphic granular structure irregularly intergrown. The abundant feldspar is in part orthoclase, in part a striated feldspar, not 

determined but very likely albite. The feldspars arc partly fresh, partly altered to 

a brownish, low-refracting aggregate, perhaps kaolin. Occasionally the feldspar 

occurs in idiomorphic crystals in quartz. Tourmaline is abundant in highly pleochroic idiomorphic crystals. It has been observed included in feldspar. As a rule 

quartz and tourmaline are closely intorgrown and contemporaneous. The tourmaline makes up about one-third of the slide and is segregated in one portion of it. 

Pyrite is abundant, closely associated with the tourmaline, with which it is intergrown and contemporaneous. Pyrite occurs idiomorphic in quartz and vice versa. 

Biotite is a subordinate but common mineral, included in the quartz and feldspar 

and probably older than these. Sphene is a common accessory. Occasional magnetite was observed, perfectly octahedral striated crystals being included in quartz. 

A little chlorite is present. 

In the hand specimens the different minerals are often grouped or segregated in 

pegmatitic fashion, so that bunches of almost pure tourmaline originate, others of 

pyrite, others of feldspar, etc. The tourmaline and pyrite are generally grouped 

together. 

In many places this pegmatitic type becomes more granular and regular on the 

edges, and seems to show transition phases, by decrease of tourmaline and pyrite 

and increase of biotite, to the wall rock. 

In many of the specimens of the pegmatitic phase gold occurs in beautiful, 

sharp crystals, easily visible or even conspicuous to the naked eye. In the body of 

the rock these gold crystals are sometimes intergrown with the pegmatitic or granitic 

quartz, and they thus occur in one case in a phase intermediate between the granite 

and the pegmatite. These crystals arc often perfectly clean and free from iron 

stain. More often the gold crystals occur close to or lining the walls of tiny druses 
156 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

which are frequent in the rock, in which cases they are intimately associated with 

tourmaline, quartz, and feldspar (probably albite) crystals. In one case two small 

idiomorphic tourmaline crystals seem entirely inclosed in a sharp crystal of gold. 

In some cases tiny crystals of probable feldspar (albite~) are subsequent to the gold. 

The gold crystals often occur close by unoxidized pyrite, showin.g that the free 

gold is not one of tho secondary products dependent upon oxidation. 

All the minerals of this rock, which appears to the writer to be a true pegmatitic 

phase of a granitic rock, are primary and practically contemporaneous. The periods 

of crystallization overlap, yet there is a rough order of sequence which for the principal minerals may be expressed as follows: 

1. Biotite. 

2. Feldspar. 

3. Feldspar, magnetite pyrite, tourmaline, quartz, and gold. 

In the Black Hills of South Dakota, according to Professor Kemp,a pegmatites 

in the vicinity of Harney Peak have proved to be gold bearing. These ores are 

regarded by Professor Kemp as similar in character to those described by Hussak 

from Ouro Preto in Brazil and to some in the Transvaal. 

Prof. C. vV. Hall b has furnished notes on eastern and central Minnesota, where, 

in connection with intrusions of hornblende-biotite granite, there are "granitic 

veins." These are "locally pegmatitic, with coarse and well-developed feldspar 

individuals embedded in a matrix of hornblende and biotite, while elsewhere they 

are finely textured, possess a reddish color, and are highly siliceous in composition." 

Associated with these are veins of quartz. In the St. Louis River district the veins 

when wide become pegmatitic. The veins sometimes carry segregated sulphides 

and siderite. One on Kettle River has been explored for gold. 

On the north shore of Long Island, Prof .• J. F. Kempe observes that pegmatites 

arc abundantly developed in connection with granites, and all grades are shown up 

to perfectly pure quartz. One of the largest quartz veins, which Professor Kemp 

thinks belongs to the pegmatitic series, carries in portions ferruginous minerals and 

traces of gold. · 

MEXICO. 

In Mexico, in the Altar district, Sonora, according to Jose G. Aguilera,d the 

;numerous veins of Sierra Pinta del Bajio are in pegmatite, which cuts crystalline 

schists. 

The veins carry quartz, pyrite, chalcopyrite, a very smnll amount of galena anrl blenrle, and contain free 

gold along the crests. The veins suddenly pinch out along both the course and dip and prcgent n well characterized lenticular formation resembling a string of beads. 

Prof. G. P. Merrill has described free gold in granite from Sonora in Mexico. 

This gold occurs in crystalline particles included in feldspar and quartz and is designated by Professor Merrill as "a product of cooling and crystallization from the 

original magma."e 

a Ore Deposits of the United States, 3d cd., pp. 310-314. 

b Ke>ewatin of eastern and central Minnesota: BulL GeoL Soc. America, voL 12, pp. 367-8-9, 1901. 

cOre Deposits of the United States, 4th ed., p. 383; Trans. Am. lust. Min. Eng., voL 31, p. 182; Genesis of Ore Deposits 

p. 693. 

d Trans. Am. Inst. Min. Eng., voL 32, p. 518. 

e Am. Jour. Sci., Apr., 1896, p. 309. 
CHAPTER V. 

DEPOSITS OF NONMETALLI.FEHOUS ~HNERALS. 

ALUM AND SULPHUR. 

LOCALITY. 

About 10 miles north of Silver Peak there lies a deposit of alum and sulphur. 

This has been many times located and prospected as a sulphur mine, but not until 

recently has the relatively large amount of alum in it been recognized. No important work has yet been done on the deposit. 

MODE OF OCCURRENCE. 

At the locality mentioned there is an elongated dike-like or neck-like mass of 

rhyolite, having all the appearance of being intrusive into gently folded white and 

red sedimentary rhyolitic tuffs of Tertiary age. In parts the rhyolite is easily recognizable as such; in other portions it is decomposed to a white powdery variety. 

This is especially true of two portions examined, about 600 feet apart; one some 200 

feet in diameter, the other about 30 feet. The former, at the south end of the area, 

contains the chief alum and sulphur deposits. The latter contains sulphur, but no 

alum. 

In the larger area the decomposed rhyolite shows sulphur throughout., coating 

all cracks and crevices, but generally not over a fraction of an inch thick. With the 

sulphur is closely associated pure alum, which has a different habit, forming veins, 

some of them several inches thick, that split and ramify irregularly throughout the 

broken masses of altered rhyolite. Analysis in the chemical laboratory of the United 

States Geological Survey shows it to be an ordinary potassium alum (kalinite). 

There are also occasional gypsum seams, of the same habit as the alum, but much less 

abundant. Bright-red stains are associated with the sulphur and alum, which were 

thought in the field to be possibly cinnabar. The small quantity represented by 

these spots is not suitable for chemical examination. In 1903, however, Dr. George 

I. Adams investigated the Rabbit Hole sulphur mine, in northern Nevada, near 

Humboldt House station, on the Southern Pacific Railway, where the geology 

appears to be not greatly different from that of the place being described, and has 

found there similar bright-red stains. Analysis of these shows them to be really 

cinnabar (sulphide of mercury), and there can be little question that the stains of the 

deposit near Silver Peak are of the same material. 

The smaller area above noted, north of the principal deposit, shows sulphur in 

crevices, in moderately large perfect crystals nearly or quite isolated. 

157 
158 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

When exposed to the air, the alum rapidly dehydrates and crumbles to a white 

powder, so that it is not conspicuous in the outcrop, and the real amount of it present 

is visible only when it has been freshly taken out. 

MANNER OF FORMATION. 

These areas are evidently pipes or chimneys through which sulphurous volcanic 

gases have ascended. Since the rhyolite bodies are probably intrusive, the gases 

seem to have followed the intrusion. This action is familiar around recently active 

volcanoes, and it is called solfataric action, from the fact that sulphur (Italian solfo) 

is deposited by it. For this reason the volcanoes of Italy, Mexico, and other places 

yield a large amount of the world's sulphur. The formation of alum by the escaping 

steam and gases of these solfataras is also known to occur in many localities. While 

the sulphur is a direct sublimate from the sulphurous gases, as its occurrence just 

described in the Silver Peak deposits indicates, the alum, which is a hydrous sulphate 

of aluminum and potassium, is formed by a combination of the steam and the 

sulphuric acid emitted from the solfataras with the potash and aluminum contained 

in the rhyolite. This combination is rendered possible by a preliminary decomposition of the rhyolite by the escaping gases. The presence of cinnabar is also 

interesting, since this mineral is one of those which has been found as a sublimate 

on the walls of crevices in volcanoes, as for example, at Vesuvius, where it has 

been deposited by jets of escaping gases. The deposit of cinnabar at Steamboat 

Springs, some distance north of here and just north of Carson, is also significant. 

COMMERCIAL ASPECTS. 

Though the alum in these prospects is present in far larger quantity than the 

sulphur, it is somewhat more localized. It forms an irregular network of veinlets, 

and yet from the manner of formation the chimney undoubtedly continues downward. The decomposed rhyolite is so friable that the material could easily be worked 

on a large scale. The rhyolite itself in the alum locality has been found by analysis 

to contain a large percentage of alum. The whole deposit, therefore, would have to 

be worked together, and the sulphur could also be collected as a by-product. 

BORATES AND SALT. 

DESCRIPTION OF DEPOSITS. 

Within the area of the Silver Peak quadrangle there are several playas or alkali 

flats, which occupy the areas of greatest depression in the desert valleys between the 

mountains. These playas consist of level areas of mud, which are hard and dry, or 

wet, according to the season of the year and the frequency of the rains. After any 

considerable rainfall sheets of water collect in these depressions and form shallow 

and evanescent lakes. The mud of these playas is frequently intermixed with and 

crusted with deposits of soluble salts, consisting in this region chiefly of common salt 

and borates of lime and soda. These playa deposits have been described by Mr. 

H. W. Turner, from whose work the following quotation is taken: 

The playa deposits comprise four areas in Fi~h Lake Valley, one in Clayton Valley, and one in Big Smoky 

Valley, locally known as the San Antonio marsh. All of the playas in Fish Lake Valley within the quadrangle 

... 
BORATES AND SALT. 159 

contain borax salts and are being worked for borax. The Big Smoky playa shows a thin white coating, which 

consists largely of chloride of sodium, ovN many square miles. Over other portions of the valley are deposits 

of other salts, such as sulphate of soda, which are ordinarily termed alkali. 

On the economic map then' P.re shown area.s containing workable deposits of borax salts and of table salt 

or chloride of sodium. The borax snits are confined to Fish Lake Valley and the table salt deposits to Clayton 

Valley. Chloride of sodium is, however, abundant in all the playas, but nowhere sufficiently concentrated and 

pure to be of economic Yalue outside of Clayton Valley. 

There are also other salts, sulphates, and chlorides which form white incrustations on thA Fish Lake and 

San Antonio playas. c\. series of playP .. deposits was collected by ,J.D. Reed and sent to Washington for analysis. 

The chloride of sodium deposit north of the Pacific borax works in Fish Lake Valley contains sodium sulplmte and other impurities (see analysis 4) and is not valuable unless the impurities can be removed. The 

chloride of sodium and borax lands are outlined only approximately. Further investigations will doubtless 

extend these areas. 

Analyses of playa deposits. 

[Mr. George Steiger, analyst.] 

1. 2. 3. 4. 5. 

----------------------]------------

Insoluble a . . . . . . . ............................................. . 

H,O ...................................................................... . 

CaO.......... ........................ . ............................... . 

3.46 

12.24 

5.72 

22.66 

25.56 

35.42 

20.90 

8.05 

4.86 84.49 

6.00 ......... . 

Present. 

Na,o ..................................................................... i 43.G9 1 3.25 6:~~ / 46.08 Do. 

~;~_: __ !,· ;~;~ ~:"~I ,:;~ ~:.~ co,................................................................ . .. [ ... ·1·7-·.4·9··· 2.20 10·.9163 il .... 6. _.0·7· .......... . AJ,O,, MgO, ctc.b ..................................................... . 

L""' I :~::I :::I :::I :::I a In 2 and :l dilute HCl was the solveut. Iu 1, 4, and 5 water was used. 

bBy difference. 

'----

No. 1, collected about 100 feet from the crossing B. M. in Fish Lake Valley, is composed of sodium carbonate, sodium 

sulphate, some borax, and probably a little sodium bicarbonate. 

No.2, frmn 150 feet northeast of the Pacific borax works, is principally sulphate and borate of lime, with a smaller 

amount of sodium sulphate and borate. 

No.3 is a sample of the little wbite nodules locally known as cotton balls. This is principally borate of lim~ and borax, 

with a little sodium chloride and carbonate. 

No.4 is from the large marsh north of tbe Pacific Borax Company mill. and forms a white incrustation with irregular 

surface over the entire marsh. It is principally sodinnt chloride or table salt, with smaller amounts of sodium sulphate, 

sodium carbonate, and borax. 

~o. 5 is from the San Antonio marsh in Big Smoky Valley. There appear to be no borax or other salt deposits on the 

San Antonio marsh of any value. The surface soil is whitened by salts, but the analysis of this soil shows that they are 

present only in trifling amounts. 

At the time of the writer's visit the borax industry within the area of this 

quadrangle was dormant, and no systematic work w.as being done on the salt deposits. 

From the salt deposits in the neighborhood of Silver Peak supplies are drawn for the 

village of Silver Peak, and occasionally a few sacks are taken away to neighboring 

country stores and sold. This salt is prepared by digging a hole a foot or two feet 

deep in the marsh until water is reached and then letting this water evaporate. 

It is claimed that the salt thus produced is .99 pure. 
160 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

RELATIONS TO OTHER AREAS. 

The borax-bearing playa in Fish Lake Valley is the southernmost of a series of 

several playas or borax marshes which have produced a large quantity of borax 

and have played a most important part in the development of the American borax 

industry. These marshes are, besides the Fish Lake marsh, the Columbus marsh, 

which lies a short distance due north of the Fish Lake marsh and in the same general 

valley; the Rhodes marsh, which lies still farther north of the Fish Lake marsh and 

a short distance south of Sodaville, and the Teal marsh, which lies a short distance west of the Rhodes marsh. 

Although the presence of borax in water from Mono Lake was discovered as 

early as 1860 by Doctor Veatch, and this fact was regarded by him as evidence of 

the presence of borax deposits in l'\evada, the recognition of economically important 

deposits did not take place until some years later. In 1864 Columbus marsh was 

located as a salt bed. Some borate of lime was found and was afterwards recognized 

as such, but no importance· was attached to the discovery. The Teal marsh, which 

has been one of the most productive of the borax fields of the Pacific coast, was 

discovered in 1873 by one of the Smith brothers, who now control the borax industry, 

and from this beginning the great production of American borax was started. 

Extensive operations have also been can:ied on in the Rhodes, Columbus, and Fish 

Lake marshes. 

GENESIS OF THE DBPOSITS. 

The incrustations of various salts covering the playas are among the most recent 

geological deposits. In part they have undoubtedly been crystallized from the 

waters which sometimes cover the playas and which in most places, even in the dry 

seasons, can be found by digging a few feet down into the mud. In the case of some 

playas in this region, also, there is evidence that during earlier periods of comparative humidity, the water supply was sufficient to form perennial lakes similar to the 

inelosed lakes still found in various portions of this arid province. In such cases 

the deposit of salts has been largely derived from the evaporation of the saline lake 

waters. In any ease, whether the water which has covered the playas has bt>ell 

sufficient to form a permanent body or only temporary sheets, it has been derived, 

in part at least, from the drainage of the surr<,mnding mountains. l'\ one of these 

dry lakes, as the playas are sometimes called, have any outlet, so that evaporation 

is a process of the utmost importance, and nearly all the salts in the waters become 

concentrated. From these considerations the explanation naturally arises that the 

salts in the playa deposits of the alkaline lakes represent the concentration of the 

very small quantity of salts contained in ordinary drainage water, and that the 

supply was derived from the leaching of the disintegrated rocks of the areas which 

drain into these depressions. This explanation has been somewhat widely held 

for the borax deposits of the desert Nevada region. About 1890,a however, beds 

of borate of lime or colemanite were discovered forming part of the early Tertiary 

sediments of this region, which had been in part upfolded and faulted so as to form 

part of the hills and mountains. b In the valley playas near these Tertiary borate 

a According to G. P. Merrill Nonmetallic Minerals, 1004, p. 316. 

b Storms, W. H., Eleventh Ann. Rept. State Geologist of California, 1892, p. 345; Campbell, M. R., Bull. U.S. Geol. 

Survey No. 200, p. 17; Spurr, .J. E., Bull. U. S. Geol. Survey No. 208, p. 100. 
BORATES AND SALT. 161 

deposits, borates occur also, and in these cases it became evident that a large part 

of the supply was secondary and derived from the leaching of the Tertiary borates 

in the hills rather than from the faint traces of boron which may exist in the other 

rocks. 

Earlier in this report (p. 21) the writer has shown that these older colemanite 

beds are characteristic of the broad belt of earlier Tertiary sediments which runs 

northwest and southeast in the region lying immediately east of the Sierra Nevada 

and which reaches at least as far north as northern Nevada and as far south as the 

Mojave desert. The internal evidence of these beds shows that much of the material was laid down in inclosed lake basins and that the colemanite beds are probably 

the result of the evaporation of Tertiary alkaline lakes during periods of aridity. 

The belt of these continental Tertiary deposits is practically that of the playa borax 

region, so that the writer has regarded it probable that much of the material in the 

playa deposits is leached from Tertiary beds in the surrounding mountains, even 

when these beds do not show any considerable aggregation of colemanite and other 

minerals due to evaporation. a 

Though the above explanation is logical, it does not seem to cover the whole 

question. Within the Silver Peak quadrangle, as already described, the Clayton 

playa, near the village of Silver Peak, contains abundant salt deposits, but so far 

as known no borates, while the Fish Lake playa contains abundant borates as well 

as salt. The drainage area of each of these playas includes large districts of the 

upturned early Tertiary sediments, so that the playa deposits would be naturally 

expected to show the same characteristics. There is, however, another phenomenon 

which explains this difference and by so doing becomes an important factor in the 

explanation of the playa deposits in general. At Silver Peak a hot saline spring, 

the waters from which have not been analyzed, flows out very near the edge of the 

mountains and at the edge of the playa, and on the opposite or east side of Clayton 

Valley another hot spring emerges. Moreover, hot waters underlie the upper crust 

of the whole playa or marsh, especially at certain seasons of the year, according to 

the testimony of the inhabitants. It is plain that the incrustations of salt are 

largely derived from these hot spring waters. In Fish Lake Valley also there are 

highly saline springs, although these are not hot; and a number of mounds show the 

presence of springs formerly active, but now extinct. The explanation of the difference in the character of deposits in the playas which receive the drainage from 

similar rocks seems to lie in the presence of these springs, which, (the hot springs, at 

least), must be of deep-seated origin and must furnish waters differing from one 

another as to the salts which they hold in solution. 

This was also the explanation offered by Prof. Joseph Le Conteb for the localization of the different salts at the Rhodes salt marsh. 

The marsh is nearly circular in form, and, as near as I can judge, about 2~ to 3 miles in diameter and contains about 5 or 6 square miles. The central part (perhaps 1 square mile or more) is covered with pure saltchloride of sodium. Around this to the margin the nature of the deposit differs in different parts. In some 

parts borax in the form of crust: in some, borax in the form of tineal; in some, ulexite (a soda-lime borate); 

a According to Mr. Hieronymus, keeper of the Cold Wells watering station on the edge of the Columbus marsh, borax or 

cotton ball occurs in the Tertiary Monte Cristo Mountains, just north of the Silver Peak quadrangle. The mountains are 

part of the drainaP,"e area of Columbus marsh. 

b Third Ann. Rept. State Mineralogist, California, 1883, p. 51. 

13002-~o.55--06----11 
162 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

in some, sulphate of soda, and in some carbonate of soda. Common salt is found nearly everywhere, more or 

less mingled with the other s~tlts, but in It pure condition only in the centml portion of the marsh. * * * 

If the marsh is a simple dried-up lake, the waters of which contained all these salts, then it would be impos· 

sible to account for the localization of the v~trious kinds. The former lake, therefore, must have been supplied 

also largely by springs coming up in the lake bottom, and these springs brought up various kinds of salts, some 

one kind and some another. After the lake dried up, these springs still continuing to act would then commence to loealize their products. This they are s~ill doing. Thus I account for the localization of most of the 

kinds of salts. In addition to this, I think the common salt, as the most abundant ingredient of the lake water, 

was probably left evervwhere as a crust, but subsequently was leachPd out and accumulated in a vPry pure 

form in the lowest or central part. 

The above-mentioned explanations carry back the history of the accumulation 

of borax and other salts to a certain point, but do not satisfy the investigator as to 

the real cause why borates should be concentrated in this belt. Boron is one of the 

rarer elements, making up, according to J. H. L. Vogt,a between 0.01 and 0.001 

of 1 per cent of the earth's crust. In the relative order of abundance it belongs in 

the same group with nickel, strontium, lithium, bromine, and beryllium. The 

concentration of this rare element into deposits so rich and abundant that the material becomes commercially cheap· and available for domestic purposes certainly 

implies some active process that has separated the element from the vastly more 

abundant elements which accompany it in rocks and which likewise pass into ordinary aqueous solutions. 

An explanation of this may be offered after considering the associations under 

which quantities of boron appear in various places. Compounds containing boron 

in commercial quantities occur in two principal ways: (1) In deposits from evaporated dry lakes, as in the case of the Nevada belt, and (2) in deposits from volcanic 

fumaroles. In the first instance we have of course still to seek the ultimate origin, 

while in the second it seems possible that we have an explanation of this origin. 

Pure boric acid, or sassolite, occurs chiefly in volcanic fumaroles, to a very 

slight extent in certain spring waters, and in traces even in sea water.b It has been 

obtained in commercial quantities from fumaroles in two Mediterranean localitiesone in Tuscany in Italy and one in the Lipari Islands. At the first-named 'locality 

hot vapors issue from the ground at many places. These consist chiefly of steam 

with carbonic acid. In 1818 a method was found to condense the steam and to 

crystallize the salts contained in solution. By this process a commercial product 

was obtained which contains 76.5 per cent of crystallized boric acid and 23.5 per 

cent of other materials-namely, sulphates of ammonium, magnesium, calcium, 

sodium, potassium, iron oxide, alumina, and manganese oxide; also ammonium 

chloride, sulphuric acid combined with boric acid, silica, and traces of organic 

materiai.c 

Exhalations of steam containing boric acid have also long been known to proceed from the crater of Stromboli, on the island of Vulcano, in the Lipari group. 

At Vulcano the boric acid is precipitated together with sulphur from exhalations of 

steam containing sulphureted hydrogen, which emerge boiling hot from fissures. 

The sulphur deposited is so abundant as to become a commercial product, and 

a Zeitschr. fiir prakt. Geol., 1898, p. 325. 

b Bischof, Chemische and physicalische Geologie, vol. 2, p. 277. 

c Bischof, op. cit., p. 268. 
BORATES AND SALT. 163 

alum is also a product of the fumarolic activity, as well as ammonium chloride. In 

1864, according to Bischof, a the works engaged in utilizing these fumarolic exhalations produced, besides boric acid and sal ammoniac, 1,700 pounds of refined sulphur and 600 pounds of pure alum. 

During an eruption of Vesuvius in 1851 boric acid was found in fissures. b 

The discovery of borax on the Pacific coast of the United States was made in 

18f56 by Dr.John A. Veatch.c In the vicinity of Clear Lake, California, Doctor Veatch 

found hot sulphur springs containing borax and boracic acid in solution, together 

with chlorides and sulphates. These springs also contained carbonic acid. Doctor 

Veatch observes: "The whole neighborhood bears marks of comparatively recent 

volcanic action. Indeed, the action has not ceased yet entirely. Hot sulphurous 

fumes issue from several places." The waters of this district also contain iodine. 

The eruptive mud from the mud volcanoes of the Colorado desert, San Diego 

County, contains boracic acid.d 

The connection of large concentrations of boron in the form of boric acid and 

various borates with fumarolic activity following volcanic eruptions is thus clearly 

demonstrated for some of the most important localities in the world. If this 

observed origin be applied to the explanation of the borate deposits which have 

been formed by evaporation of the waters .of arid regions the reason for the distribution of these deposits is clearly understood. The Tertiary sediments which contain colemanite beds in Nevada and California were formed during a long period of 

active volcanism, which is hardly yet extinct.' The exhalation of boron compounds 

attendant upon the cooling of eruptive volcanic rocks would provide a large supply 

of this material, which would all pass into the waters of the region. The portions 

which were carried out in steam from escaping fumaroles would be brought back to 

the surface in the form of rain, while a large portion in the later stages of cooling 

would come to the surface in solution in the hot springs which succeed the fumarolic 

phase of expiring volcanic activity. The aridity of the climate is a very essential 

factor in producing from these solutions, by natural evaporation, workable deposits 

containing borates. In a region which has free drainage to the sea or to large lakes 

the borates anil associated salts are carried off. Thus the various inclosed lakes of 

Nevada and California, such as Owens, Mono, and Pyramid lakes, contain boracic 

acid, as well as other salts, and the same is true to a less extent of the sea water, 

where the salts are more diluted. 

Some geologists have believed that deposits of borates were the result of the 

leaching of rocks carrying minerals containing boron, such as tourmaline, axinite, 

etc. Of the boron-bearing minerals which are rock constituents tourmaline is the 

most abundant and is frequent as a constituent of granitic rocks and in the metamorphic schists, especially in the neighborhood of granites. Tourmaline has been 

occasionally found altered to mica, chlorite, and talc, and in the process of alteration 

its boric acid has been separated out and may have formed borates.f On the 

a Op. cit., p. 272. 

b Third Ann. Rcpt. California Mining Bureau, 1883, p. 61. 

c Ibid., pp. 14~20. 

a Ibid., p. 59. 

e Spurr, J. E., Prof. Paper U.S. Geol. SurYey No. 42, p. 82. 

I Bischof, op. cit., pp. 277-278. 
164 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

whole, however, tourmaline is very resistant to decomposition, remains unaltered 

when the surrounding minerals are decomposed, and so passes in a fresh condition 

from igneous metamorphic rocks into clastic rocks. a The study of the granitic and 

metamorphic rocks of the Silver Peak quadrangle and other portions of the region 

shows the presence of tourmaline rarely and in very small amounts, not nearly so 

great as in many regions which contain no borax deposits. This explanation is 

therefore out of the question for the district under consideration. Moreover, it is 

now generally recognized, as it was not at the time that the above explanation was 

offered, that the tourmaline in these rocks is itself the result of exhalations from 

cooling igneous rocks, similar in many respects to those of volcanic fumaroles, but, 

on account of being at great depths and under great pressure, capable of crystallizing 

in silicates, such as tourmaline, which are not po:.sible under surface conditions. 

According to the conception of the writer, therefore, the concentrations of boric 

acid in volcanic fumaroles and in the deposits of evaporated lakes or playas in arid 

volcanic regions owe their existence to a process of natural concentration, the first 

stage of which was similar to that which has produced the concentrations of boron 

in the form of tourmaline and other silicate minerals in and near bodies of siliceous 

intrusive rocks, while the second stage was dependent upon concentration by evaporation from surface waters. · 

A discussion of the probable origin of the Nevada hot springs, which are here 

regarded as the sources of the various playa salts in the region of Silver Peak, has 

been given by the writer in a previous report. b In this investigation it has been 

concluded that, although many of the springs are undoubtedly of mixed origin, and 

m many cases a part of the water may be atmospheric, a large portion is probably 

magmatic, and has its origin in exhalations from volcanic rocks cooling in depth. 

To solutions contained in such hot springs (of Tertiary age) the Tertiary metalliferous ore deposits, such as those at Tonopah, have been ascribed. For the Tonopah 

district the presence in these solutions of sulphur, carbonic acid, chlorine, and fluorine has been inferred. Vein fillings like those at Tonopah, constituting the metalliferous ores of the Nevada Tertiary province, represent the most easily deposited 

materials held in these solutions, such as silver, gold, silica, etc. These materials 

were deposited in the fissures at some distance from the surface, while the more 

easily soluble and more volatile materials were deposited higher up or at the surface. 

Such deposits are considered to be represented by the deposits of sulphur, alum, 

borax, and salt in the Silver Peak quadrangle. The presence of probable cinnabar 

in the alum-sulphur deposit at Silver Peak, above noted, seems to furnish a connection between these nonmetalliferous deposits and those which contain abundant 

metals, and the resemblance of this occurrence to that at Steamboat Springs is a 

step further in the idea, for at Steamboat Springs not only is the cinnabar more 

abundant, but gold has been and is being deposited from the waters. In a portion 

of the borax belt some distance south of the Silver Peak district, in Searles Marsh, 

northeast of Randsburg, in California, playa deposits have been found to contain 

small quantities of silver chloride and chlorobromide (cerargyrite and embolite), 

together with the more ordinary nonmetallic minerals, comprising calcium, strona Rosenbusch-Iddings, Microscopical Petrography of the Rock-Making Minerals, 1889, pp. 184-185. 

b Prof. Paper U.S. Geol. Survey No. 42, p. 256. 
U. S. GEOLOGICAL SURVEY PROFESSION AL PAPER NO. 55 PL. XXIII 

OPENING ON COAL SEAM, WILLIAM GROZENG E R, DISCOVERER OF T HE FIELD , STA N DING BY. 
BORATES AND SALT-COAL. 165 

t~um, and sodium phosphates; calcium, magnesium, and sodium carbonates; calcium and sodium borates, potassium nitrate, and sulphur. The association in these 

playa deposits and other saline beds of the halogen elements, chlorine, bromine, 

iodine, together with other elements likewise possessing volatile properties, such as 

boron and sulphur, can hardly be without very great significance, and the identity 

of these associations with those found in volcanic fumaroles is a strong argument 

for a common origin. 

COAL. 

At the north end of the Silver Peak range, near the northern end of the quadrangle, and jw>t south of the road between Silver Peak and Candelaria, coal beds 

occur in Tertiary s!)lndstones, shales, and volcanic tuffs, which contain fresh-water 

shells and Tertiary plants (seep. 20). 

GEOLOGIC CONDITIONS. 

On the south, only a short distance from the road, these sediments abut abruptly 

against a massive cliff or scarp of rhyolite, itself also probably of Tertiary age. 

Between the rhyolite o~ the south and the sediments on the '1orth there is probably 

a heavy fault, running in an east-west direction. The coal-bearing beds dip northeast at comparatively slight angles, but the dip increases as the fault is neared, and 

in the immediate vicinity of the fault the beds acquire a reversed dip and constitute 

a local anticline running parallel to the line of displacement. The beds on the south 

limb of this fold sometimes have considerable dip. This phenomenon seems· to be 

due to the dragging down of the strata along the fault. It is believed that the downthrow has occurred on the south side, and that the present greater height of the 

rhyolite. on the south is due to its superior hardness, the soft sandstones and shales 

having been worn away relatively more rapidly. In support of this belief the downdragging of the beds near the fault just described may be appealed to, together with 

the fact that several minor faults near the main fault were found to have a downthrow to the south. Also it seems probable that the rhyolites on the south side may 

represent a higher horizon in the Tertiary than the beds on the north (Pl. XXIV). 

DESCRIPTION OF THE COAL. 

The coal in this district is said to have been discovered by William Grozenger, 

of Candelaria, in 1893, and the outcrops of the seams are now continuously located 

(Pl. XXIII). The chief seams are ruur in number. Some of them outcrop for a 

distance of 3,000 to 4,000 feet, in a northwest-southeast direction. Mr .. Grozenger, 

who is very familiar with the district, has elassified tht-3 seams, counting from the top, 

as the first, second, third, and fourth. The perpendicular distance between the first 

and the second seam is estimated by him to be 150 feet; between the second and 

third, 70 feet, and between the third and fourth, 130 feet. The uppermost seam, 

No. 1, seems to be relatrvely poor and small, and, as exposed in outcrop, of little 

value. No.2 seam is in coal shale and is several feet thick. Openings on this seam 

show the coal to be thin bedded and to occur in connection with beds of rhyolitic tuff. 

In places, also, sheets of glassy rhyolite, evidently subsequent in age to the coal beds, 
166 ORE DEPOSITS OF SILVER PEAK QUADRANGLE, NEVADA.. 

have intruded and cut off the coal (fig. 40). There is a good deal of slate parting 

or bone present. No. 3 is also in coal shale and is of better quality and thicker than 

No. 2. No. 4 lies close to the fault, is in sandstone, and shows 6 to 8 feet of coal 

of much better quality than the upper seams. Some of this coal has a brilliant 

luster, while the coal of the other seams is of a dull color. It has been opened up 

in only one place, where it is overturned and dips against the fault. Here the lower 

2! feet is cleaner coal than the rest. It was used as a forge coal by Mr. Grozenger 

and affords a coke. Analysis by Mr. George Steiger, of the United States Geological 

Survey, of a general SJ,mple taken from a picked block 8 inches thick, gave the 

following results: 

Analysis ofcoalfrom Esmeralila County, Nev. 

Moisture............ ......... . .. .. ................................................ ... .......... 0.94 

Volatile matter .............................. ." ............. .. , .. ,,._.: .................. ·........... 37.35 

Fixed carbon.......... .................... . ..................... . ............................. 42.63 

Ash................... . ......................................................................... 19.08 

Total. .•....................... : .......................................................... 100.00 

Coke good. 

This analysis was made after the sample had been ly,:ing exposed to the air 

about six months. The 

amount of moisture given 

is therefore probably less 

than when the coal was 

taken from the mine. The 

important fact that the coal 

does not slack rapidly on 

~ 

/ 

COAL_ 

o~~~~~~s--------~10feet 

FIG. 40.-Section exposed by short tunnel of coal vein No.2, showing intrusion 

of rhyolite. 

exposure was, however, determined by this experiment. The analysis shows 

a light, bituminous coal, 

somewhat poorer than the 

Colorado bituminous coal, 

and, except for the larger 

amount of ash, comparable with some of the high-class Pennsylvania coals. It is 

a fairly good steaming coal and an excellent gas coal. 

An analysis of coal from the Elder-Morgan prospect, taken from unpublished 

manuscript of Mr. H. W. Turner, of the Geological Survey, is as follows: a 

Analysi.• of coal from Elder-Morgan mine, Esmeralda County, Ne·v. 

Moisture..................... ...... ....................... ...... ............................. .. 3.53 

Volatile combustible material. .................. :.............................................. 31.71 

Fixed carbon...................................... . ... . .. . ... . .... . .. .. ... . . ................... 35.95 

Ash ...... .............. ........ . . .... ........... . ..... ....... ....... . ...•. ...................... 28.81 

•rota!. ........ .....•.... . . ............ . . . . . . .. . . . . . .............. ....... .................. 100.00 

Sulphur ....... .... .. . .......... ................... . ........ . ................. ......... . ......... 1.05 

a Dr. w. F. Hillebrand, of the U. S. Geological Survey, who made this analysis, notes that the coke is coherent, but not 

much swelled . 

• 
L'. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 53 PL. XXIV 

COAL F I ELDS AT NORTH END OF SILVER PEAK RANGE. 
COAL. 167 

This analysis, according to the writer's best information, seems to be of coal 

from seam No. 2. 

On seam 3 of the Elder-Morgan locations an incline has been put down 160 

feet, with a dip of 30°. The following description and analysis is from an article 

by Mr. W. J. Stoneham: a 

At the outcrop this vein is very dirty, containing little or no coal, but within 75 feet good coal is found on 

thA roof and continues to the bottom of the incline, improving in width and quality. For the lowest 85 feet 

the coal averages 3 feet thick and is c!Aan, compact, and glossy. An analysis of coal from this seam near the 

surface made by Thomas Price, of San Francisco, showedMoisture ......... ______________ -_--------- ________ - ___ -_-_----- ___________ ----------- _____ -_-_- 1.81 Volatile matter _________________________ - __________________________________________ ---__________ 34.52 

Fixed c11rbon. _ ....... _________ ..... -·-- .. -------- ... -----.--- ___ __ _________ _____ __ 44.58 Ash. ____________________________________ - __________ . ___________ - _________________ -_-.- ____ ._____ 19.09 

TotaL __________________________________ ------ _________ ---·-- _____________________________ 100.00 

Sulphur. __ --------- ____ --------------------------- .. ----------·-------------------------·---·-· 3.62 

The coal forms a hard coke. At surface, the seam showed over 28 per cPnt ash, so that at greater depth 

it may contain less than 19 per cent. 

In these coal seams gypsum is found and some alum, and in the old workings 

iron sulphate (melanterite) and coatings of sulphur. This sulphur and the various 

sulphates are plainly secondary and are the result of the oxidation of the pyrites, 

which is present in the coal. It is interesting to consider the genesis of this sulphur, 

gypsum, and alum in connection with the presence of the same minerals in the alumsulphur prospect described on page 157. In both occurrences the formation of the sulphates, and probably of the sulphur, may be ascribed to the effect of sulphuric acid, 

working upon the bases in the rock to form the sulphates. At the coal mines the 

sulphuric acid, however, is derived from the oxidation of pyrites or iron sulphide, 

and the sulphur content in this mineral is undoubtedly of organic origin, as is the 

case with the sulphur almost universally found in coal. In the case of the alumsulphur prospect, however, the sulphuric acid and the sulphur are of direct volcanic 

origin and are inorganic, being emanations from cooling igneous rocks. 

Similar Tertiary strata exist in the Monte Cristo Mountains to the north, in 

the same general line with the Silver Peak Range. These mountains have not 

been explored by geologists, but prospectors have located coal seams in them and 

brought away specimens, some of which are dull and evidently full of ash, while 

some are brilliant looking, light, bituminous coals allied to lignite and are claimed 

to be good coking coals. It is reported that the seams in these mountains are considerably broken by faulting. Within the field at the north end of the Silver-Peak 

Range, just described, there has also been probably a moderate amount of faulting, 

which would complicate any possible future work. It is possible that the failure 

to trace the known coal seams along their strike any farther than has been done 

is due to the action of northeast faults. 

a Eng. and Min. Jour., June 23, 1904, p. 1009. 
168 ORE D.I<;POSITS OF SILVER PEAK QUADRANGLE, NEVADA. 

PROBABLE VALUE. 

In conclusion it may be reiterated that these coals in general are undoubtedly 

light and of poor quality. Nevertheless, a poor fuel may be better than none in 

a region like this, where there is very little wood supply, no water power, and where 

transportation is very expensive. If a sufficient supply of the brilliant, light, bituminous coals could be developed, they would probably be directly available for fuel. 

A more economical utilization would be the conversion of the coal into producer 

gas, a fuel whose energy could be transformed into electric power, and sent to the 

points where it is desired. 

The incoming of large mining enterprises into the region should give impetus 

to a careful and well-considered study of the utilization of this important natural 

source of energy. 
INDEX. 

A. Page. 

Acrotreta, occurrence of. ............... -... _.......... 18 

Adams, F. D., on Ontario granite ____ ------ __________ . 136 

Adams, G. I., on sulphur ore. ____ . ____ --------________ 157 

Africa, gold-bearing rocks of_ _________ -- -- _- _______ -- -_ 143 

Aguilera, I. G., on gold-bearing rocks of Mexico_ _ _ _ _ _ _ 156 

Alaska, gold-bearing rocks oL _______ ------- _________ 152-152 

gold-bearing rocks of, conclusions concerning ____ 14,129 

Alaskite, composition oL __ -- ___ - ___ -------- _ 103,105,107-108 

crystallization in, plate showing_------- ______ ----_ 106 

dike of, figure showing-------_---.--------_-------- 39 

quartz and feldspar in, figure showing _________ 46,48 

gneissoid structure in, plate showing----- __ ------_ 100 

lenses of, figures showing __________ -- __ -________ 40,45 

magmatic quartz in, plate showing.--_____________ 112 

occurrence and description of._. 9,22,39--44,passim 53-98 

pyrite in, plate showing- ___ - __ --_------_. _____ ---_ 102 

relation of quartz and. ____________ -- __ - 44-47,99--101,103 

plates showing ___________ 42, 46, 48, 98,102,104, lOG, 112 

segregations of quartz and, plate showing__ 98 

values in __ - - ___ - ___ -_ -- -- - --- - 49--50 

Alaskite, inj~,cted, plate showing- ___ -_------_ 42 

Alpine mine, description oL- __ -- ___ -_------ _ _ _ _ _ _ _ _ _ 81-83 

ores oL _______________ - ____ - _____ --- _-- ______ 83,120,121 

production of._-_ .. - __ ------·------------ _______ --- 36,81 

sections of, figures showing ......... -- ........ _____ S-2,83 

Alum, occurrence and description of._------ __ 14,157-158,167 

Ancylus undulatus, occurrence of.---_------ _____ ._____ 20 

sp., occurrence of ... _ ...................... _....... 20 

Andrews, E. C., on gold-bearing rocks of Australia._ 144-145 

on granitic rocks .................... -.............. 138 

on minerals in pegmatite _____ . ____ --- __ -.__________ 140 

Antimony in pegmatite, occurrence oL - - _ _ _ _ _ _ _ _ _ _ _ _ _ _ 141 

Aplitic rocks, age of. _____ ------ __ -- __ ------ ______ .. ___ 2fr-2G 

analyses oL _--- __ --- _- .. ------------- ..... _ _ _ _ _ _ _ _ _ 24 

occurrence and description of ................. _ .... ~J--24 

Appalachians, gold-bearing rocks oL _--- .. -_________ 153-154 

April mine, descnptwn of.---------- __ ------ ___________ 56-57 

ores of. ___ --_--- .. --_--------------------- __________ 5fi--57 

production of.- •. --- __ ---- .. ----_------- ____ .. __ .. _ 35,57 

Aprons, wash, views of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 

Archreocyathus atlanticus, occurrence oL _- ________ .. _ 17 

sp., occurrence of. ....... -- .. ------ .... --- .... ___ .. _ 17,18 

Aridity, periods of, deposits in.- __ - __ --_ .. - _______ 9,160-162 

Arroyo Grande claim, description of ___ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ 89 

section of, figure showing--- __ .. __ --_ ...... _ .. _____ 88 

Arsenopyrite, occurrence of.---- ___ .. _-- __ .... _____ 68--69,117 

Asia, gold-bearing rocks of. __ .- __ - ___ --______________ 145 

Australia, gold-bearing rocks of. ___ ._-- _______ . _____ 143--145 

B. 

Barrel Springs, prospects at _____________ .. _________ .. _ 96 

Barvir, H. L., on gold-bearing rocks in Bohemia.______ 143 

Belmont district, description of. ______ -_____________ 124-125 

BeresoYsk, Russia, gold-bearing rocks near _________ .__ 142 

Page. 

Big Smoky Valley. playa deposits in. __________ - ____ 158--159 

Bischof, Gustav, on muscovite_. __ ..... ___ .. _______ ... 113 

Bismuth in pegmatite, occurrence of._________________ 140 

Black Warrior mine, description of_ _________ .. ________ 73--74 

mineralization in. ________________________ . ______ 119--120 

ores oL ____________________________________ 73--74,119--120 

section of, figure showing __ .. ___ .. ___ .. ____________ 73 

Blair group, gold of. ____________________ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ 11, 34 

map showing. ___________________ .. ________________ 34 

mill of. ____________ .. _________ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 34 

plate showing__________________________________ 26 

production of. ___ .. _____ .. ____ .. _____ .. ___ .. ___ .___ 35 

section at, figure showing ______ .. ____ .. __________ .. 41 

Bohemia, gold-bearing rocks of. _______________ . ______ . 143 

BOmmel, Norway, gold-bearing rocks of______________ 142 

Borates, origin of. __________ .... __ .. _________________ 164-105 

See also Borax. 

Borax, deposits of, description of.. ____________ - _____ 158--159 

deposits of, genesis oL- __________ -- _____ .. _- _____ 160-165 

occurrence of.._ .... ____________ ... ____ 9,14,15,21, 158 

relations of, to other areas_____________________ 160 

Boron, occurrence of. _____ .. ____ .. _____ .. ______ 14-15, 1Gfl..-1D5 

variety of. ____________________________________ .. _ _ _ 162 

Brazil, gold-bearing rocks of. __________ . ______ .. _____ 14f>.-149 

Breislak, Sci pion, on crystallization_ .. ____ .___________ ::..29 

British America, gold-bearing rocks oL _____________ 1.51-152 

British Columbia, gold-bearing reeks of__.________ 152 

Brock, H. W., on gold-bearing rocks of British Columbia. _______ .. __ .... ________________ 152 

Briigger, N.C., on metalliferous concentration._______ 138 

on paragenesis of minerals. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ 105 

on pegma tites- __ .. ____ ... ___________ .... _ _ _ _ _ _ _ _ _ 134-135 

Brooks, A. H., on gold-bearing rocks of Alaska. ____ .152-153 

Bullion claim, description oL- ____ ----- __ -- ____________ 93-94 

C. 

California claim, description of__. ________ .____________ 95 

California metallographic province, occurrence and description of. - - ___________ - -_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 128 

Cambrian rocks, analyses of. ________ .-________________ 18 

description of .. - ____ -- ____________ -________________ 17-19 

hill of, view of. . ____ - - ___________ .. _____________ .. _ 30 

occurrence of. ___ . -. --. -- -- __ ..... - -_ --. _. _ : __ . _. __ . 9 

Campeloma sp., occurrence of. ___ ._ .. _______________ .. _ 20 

Catherinet, Jules, on copper in pegmatite.____________ 139 

Charpentier, J. G. de, on pegmatites. ________ ... _ _ _ _ _ _ _ 131 

Chiatovich, John, development by __________ ... _______ . GO 

Chile, gold-bearing rocks of. ________ ... ________________ 149 

China, gold-bearing rocks of. ___ .. ______ ----- ________ .. 145 

Chloride prospect, description of. _____________ . __ .. __ 90 

Chloride type, prospects of, descriptions of ________ 90-92,122 

Cinchonidium, occurrence of. __ . _____ . _. _. __ . __ . _ _ _ _ _ _ _ 20 

Cinnabar, occurrence of. __ . ______ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 158 

Clayton, J. E., fossils collected by __ .. -------- .. _______ 17 

169 
170 INDEX. 

Page. 

Clayton Valley, auriferous sand dune in............... 96 

salt deposits in ................................. 158-159 

Coal, analyses of. .................................... 161)...167 

character of. .................................. 15,165-167 

intrusion in, figure showing........................ 166 

opening of, view of... .. .. .. . .. .. .. .. .. .. .. .. .. .. .. . 164 

occurrence of. ............................... 15,20,35,165 

section of, figure showing. .. .. .. .. .. .. .. .. .. .. .. .. . 167 

value of............................................ 168 

Coal fields, view of..................................... 166 

Coleman, A. P., on Ontario mines ............... 123-124,151 

Colorado desert, Cal., boracic acid in . . . . . . . . . . . . . . . . . 163 

Columbus marsh, borax in............................. 160 

Columbus mine, description of. ........................ 59-60 

ores of. . . . . . . . . . . . . . . . . . . . . . . . .. .. . . . . . . . .. . . . . . . . . 59-60 

production of. ..................................... 35,59 

Concentration of metals, instances of. ............... 138-141 

Cone, basaltic, near Silver Peak, view of............... 26 

Confidence prospect, description of.................... 92 

Confidence type, prospects of, description of.......... 92 

Cook Inlet region, gold-bearing rocks of......... 153 

Coolgardie, Australia, gold-bearing rocks near........ 145 

Copper in pegmatite, occurrence of.................... 139 

Corbicula occidentalis, occurrence of................... 20 

Credner, H., on pegmatites..... .. . .. .. ..... .. .. .. .. .. . 132 

Crescent mine, description of. ......................... 63-64 

ores of. ............................................ 63-64 

plan of, figure showing...... .. . . . . . . . . . . . . . . . . . . . . . 63 

production of. ..................................... 35,63 

Crosby, W. 0., on pegmatites ....................... 135-136 

Cross, Whitman, on granitic rocks.................... 137 

Crowning Glory mine, crushing in..................... 51 

description of. ..................................... 31)...52 

diorite in, influence of_ __ . __ ._ .... _ .... _____________ 47-49 

faulting and folding in............................. 51 

figure showing ____ ................ ______ ....... 51 

gold in............................................. 11 

lenses in, extent of_ ..................... _.......... 39 

nature of....................................... 38 

ore bodies in. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 

ores of, amount of. ................................ 31)...37 

enrichment of............................. 51-52 

nature of. ...................................... 37-38 

value of. .................................... 36,37-38 

production of. ..................................... 35,36 

Rections of and near, figures showing .. r _. _ ••••• __ • 38,39 

wall rock in, nature of. ............................ 3!)...44 

relations of ............................... _ ... . 

values ln ...................................... . 

workings of, map showing .. ______ ........ __ ...... _ 

See also Blair group. 

44--49 

4!)...50 

36 

Crushing, prevalence of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108-109 

Crystallization, order of. .................... 101,107,12!J.-130 

D. 

Daggett, Cal., rocks near........................... 21 

Daintree, Richard, on gold-bearing rocks of Australia. 144 

Dall, W. H., fossils determined by..................... 20 

Darrough, James, location'!! by........................ 80 

Dawson, G. M., on bearing rocks of British Columbia. 152 

De Launay, G., on gold-bearing rocks of Africa....... 146 

on gold-bearing rocks of BraziL................... 143 

on gold-bearing rocks of Chile...................... 149 

on gold-bearing rocks of Guiana................... 151 

on gold-bearing rocks of Norway.................. 142 

on metals in pegmatite ........................... 140-141 

on mispickel. . . . . . . . . . . . . . . .. .. .. . . . . . . . . . . . . . . .. . . 150 

Page. 

Deformation, history of.. ........................... 10,31-32 

Derby, 0. A., on gold-bearing rocks of BraziL ...... 147-148 

Didymograptus, occurrence of......................... 19 

Diorite dikes, influence of, on values------------------ 47,49 

intrusion of........................................ 114 

occurrence and description of .. 10,21}-27,44,passim, 53-97 

section of, figure showing. . .. . . . . . . . . . . . . . . . . . . . . . . 44 

See also Greenstone. 

Dividend prospect, description of. ..................... 87-88 

Dividend type, description of. ................. 87-89,117,121 

prospect of, section of, figure showing. . . . . . . . . . . . . 88 

Drinkwater Canyon, sections in, figures showing ___ ._. 39,51 

Drinkwater group. See Blair group. 

Drinkwater mine, crushing in......................... 51 

description of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31)...52 

diorite in, influence of....... . . . . . . . . . . . . . . . . . . . . . . . 47-49 

faulting and folding in. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 

figure showing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 

gold of............................................. 11 

lenses in, extent of. .... _ .. _ ..... ___ . __ . _ . _ . _ ... _ . _ _ 39 

nature of....................................... 38 

mineralization in. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 

ore bodies in. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 

ores of, amount of. ................................ 31)...37 

enrichment of. ................................. 51-52 

nature of. ...................................... 37-38 

value of. .................................... 36,37-38 

production of. .... __ ...... _._ ..... ___ .. _ .. __ .. _____ 35,36 

quartz lens in, forking of, figure showing.......... 109 

sections of and near, figures showing ........... 38,39,40 

wall rock in, nature of. ............................ 3!J.-44 

relations of. ................................... 44--49 

values in ....................................... 4!J.-50 

workings of, map showing ......................... 36,40 

See also Blair group. 

Drinkwater type, alaskite in, nature of. ............. 103-108 

alaskite in, relation of quartz and ................ 9!J.-101 

concentration of gold in ......................... 10!)...110 

crushing in.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 

faulting in.......................................... 108 

granitic magma in ............................... 101-103 

greenstone in, relations of.. .............. 111-112,111)...117 

metalliferous ore deposits of, genetic relations of. 99-117 

mineralization of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110--111 

mines of, descriptions of. .......................... 31)...66 

ore deposits of................................ 109 

quartz of, occurrence of gold in.................... 99 

relation of alaskite and ....................... 9!)...101 

Dyer district, description of. .......................... 84--85 

genetic relations in................................. 121 

orcs of.............................................. 85 

section in, figure showing . .......... __ ..... ___ .... _ 84 

veins of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 

E. 

Eagle Alpine prospect, description of.................. 83 

Echo Canyon, prospects in . . _ ........ ____ ...... __ ... _. 57, 58 

Eckel, E. C., on gold-bearing rocks of Georgia......... 154 

Elder-Morgan mine, coal from, analyses of. ......... 161)...167 

Emmons, S. F., on tin in pegmatite.................... 139 

Enterprise group, description of ....................... 77-80 

ores of.. ........................................ 78,80,120 

Erosion, progress of. ............................... 29-30,33 

Esmeralda mine, description of........................ 63 

production of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 

Esperanza mine, description of........................ 75 

ores of.. ........................................... 75,120 
INDEX. 171 

Page. 

Ethmophyllum whitneyi, occurrence of................ 17 

sp., occurrence of. ........... _____ ...... ---------... 18 

Europe, gold-bearing rocks of.. ...................... 142-143 

F. 

Fairbanks, H. W., on El Paso Range.................. 21 

Faults, formation of. .............................. 10,32,108 

Ferraz, L., on gold-bearing rocks in Brazil. ......... 14&-149 

Ferrier, W. F., on gold-bearing rocks in British Columbia......................................... 152 

Fesler, J. G., discovery by ... _________ ........ ____ ..... 34,85 

Fesler district. See Windypah district. 

Fish Lake Valley, playas deposits in ................. 158--159 

prospects in ........................................ 11,34 

Foley prospect, description 6f. . . . . . . . . . . . . . . . . . . . . . . . . 7 4 

section of, figure showing. . . . . . . . . . . . . . . . . . . . . . . . . . 7 4 

Forbes, E. H., on iron in pegmatite................... 138 

Fossils, occurrence of. ..... _______ .... : ........ __ ...... 17-21 

Frank No.2 mine, crushing in......................... 108 

description of. ..................................... 57-59 

mineralization in ...... _ ..... ____ .............. ___ . 110 

ores of ........................... ·'· ................. 57-59 

section of, figure showing.......................... 59 

Fuchs, J. N., on crystallization ...................... 129-130 

Fuller, M. L., on pegmatites ......................... 13&-136 

Furnace Creek, rocks of, correlation of Silver Peak 

rocks and ....................... ··;··...... 21 

G. 

Garrey, G. H., on granitic rocks....................... 138 

on iron in pegmatite ............................. 138--139 

Gascucl, -, on gold-bearing rocks in Australia........ 14.5 

Genth, F. A., on albite................................. 127 

Geologic history, outline of............................ 10 

Geology, account of. ................................... 17-33 

outline of........................................... !l-10 

Georgia, gold-bearing rocks in......................... 154 

Geologic map of Silver Peak quadrangle ............. Pocket 

Geppert, R. M., samples collected by ............... 38,47,49 

Gneiss, plate showing.................................. 42 

Gold, concentration of. .............................. 109-110 

occurrence of, in magmatic quartz ............ 11,142-156 

production of. ..................................... 35-36 

See also particular countries, districts, etc. 

Golden E aglc, description of. .......................... 62-63 

ores of.. ....................................... 62,99,101 

production of...................................... 35 

section of, figure showing.......................... 62 

Good Hope prospect, description of . . . . . . . . . . . . . . . . . . . 85 

location of. ........................................ 34--35 

Granite, analysis of.................................... 23 

crystallization of. ............................... 129-130 

See also Rocks, granitic: 

Granitic magma, crystallization of. ..... 101,107,112,120-130 

intrusion of. ..................................... 112-114 

nature of. ........................................ 101,103 

Granitic rocks, age of. ................................. 2&-26 

analyses of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 

concentration of metals in ....................... 138--141 

crystallization of. ............................... 120-138 

description of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22-23 

genesis of ................................. 101,103,130-138 

gold in............................................. 129 

intrusion of. ..................................... !l-10,31 

mineralization due to ..... _ ... _-~_ ........ 13,129,142----156 

occurrence of. .................................... 9-10,22 

Graptolites, occurrence of............................. 19 

Gravels, dissection of. .....•.........••................. 20-30 

Page. 

Great Gulch mine, description of. ................. 6&-69, 117 

mineralization in. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111, 118 

ores of.. ................................. 12,67-69,117-118 

production of. ..................................... 35,66 

sections of, figures showing ..................... 67,68,69 

Great Gulch type, metalliferous ore deposits of, genesis 

of ........................................ 117-118 

mines of, description of. ........................... 66-69 

Greenstone, age of..................................... 27 

analyses of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 

character of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 

relations of, to general intrusion ................. 111-112 

relations of gold and ............................ 116-117 

See also Diorite. 

Grozenger, William, coal discovered by .............. 35,165 

view of............................................. 164 

Guiana, gold-bearing rocks in ....................... 140-151 

Gypsum, occurrence of................................. 167 

H. 

Harrrson, J. B., on gold-bearing rocks in Guiana .. 149,150-151 

Harrison and Perkins, on gold-bearing rocks of Guiana. 149 

Hector claim, description of . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 

section of, figure showing. . . . . . . . . . . . . . . . . . . . . . . . 89 

Hector type, prospects of, descriptions of. .... 80-90,121-122 

Helpmeet claim, description of........................ 95 

Henwood, W. J., on gold-bearing rocks of Brazil .... 14&-146 

Hickey tunnel. See Drinkwater mine. 

Hogg, E. G., on granitic rocks ....................... 136-137 

IIomcstake mine, description of. ...................... 53-54 

location of, figure showing......................... 52 

mineralization in.................................. 110 

production of. ..................................... 35,53 

section of, figure showing. . . . . . . . . . . . . . . . . . . . . . . . . . 53 

Hot springs, deposits by............................... 14 

Howitt,.\. W., on gold-bearing rocks of Australia .. 143-144 

on pegmatitcs ................................... 133-134 

IIunkidori prospect, description of . . . . . . . . . . . . . . . . . . . . 89 

Hunt, T. 8., on pegllk~tites............................. 132 

IIussak, E., on gold-bearing rocks in Brazil. ........ 146-147 

Hyolithes princeps, occurrence of...................... 17 

I. 

Idaho, gold-bearing rocks in........................... 154 

Igneous rocks. See Hocks, igneous. 

Intrusive rocks, age of. ................................ 10,31 

mineralization due to_ ........ _ ... ____ . ____ ._. ___ ._ 13 

occurrence of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-10 

Iron in pegmatite, occurrence of. .................... 138-139 

Italy, boric acid in ................................... 162-163 

K. 

Keilhau, B. M., on pegmatites......................... 131 

Kemp, J. F., on copper inpegmatite................... 139 

<m gold-bearing rocks on Long Island, N.Y....... 156 

on gold-bearing rocks in South Dakota............ 156 

on pegmatitcs ................................... 135,139 

on Sierra Nevada rocks. . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 

Ketchikan district, gold-bearing rocks in.............. 153 

Klondike district, description of.•...................... 125 

Knapp, S. A., fossils collected by ..................... . 

Knowlton, F. H., fossils determined by ............... 20,21 

Kreischer, G., on pegmalites........................... 132 

Kutorgina cingulata, occurrence of.................... 17 

L. 

La Croix, M. A.; on gold-bearing rocks in Madagascar. 143 

Lane, A. C., on pegmatites . . . . . . . . . . . . . . . . . .. . . . . . . . . . 135 
172 INDEX, 

Page. 

Last Chance mine, description of.. __ ._................ 57 

mineralization in_ ... _._._ ............ ___ . __ ....... 110 

ores of............................................. .57 

Lateral secretion, theory of............................ 132 

Lavas, analyses of. ....... :............................ 28 

occurrence and description of ......... _. ___ ..... 10,27-29 

Lawson, A. C., on aplite dikes......................... 137 

LeConte, Joseph, on Rhodes salt marsh ............ 161-162 

Lehman, J., on liquid inclusions....................... 115 

on pegmatites ................................... 132-133 

Lenses, form of........................................ 109 

form of, figure showing............................ 109 

See also Ores; particular mines, etc. 

Leuciscus sp., occurrence of............................ 20 

Levat, E. D., on gold-bearing rocks in Siberia......... 145 

Limestone schist, values in.................. 50 

Lindgren, W., on gold-bearing rocks in Australia..... 144 

on gold-bearing rocks in Idaho.................... 154 

on gold-bearing rocks in Montana................. 154 

on veins in Sierra Nevada ....................... 126-127 

Linguloids, occurrence of. ............................. · 18 

Lipari Islands, boric acid in ........................ 162-163 

Liquid inclusions, occurrence of ...................... 99,114 

Lithium in pegmatite, occurrence of................... 140 

Lone Mountain, mines of. ....................... 11,34, 75-83 

mines of, ores of, genetic relations of ............ 120-121 

production of...................................... 36 

rocks near_ .. _ .. ___ . _ . _ . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 

veins of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12, 120 

Lone Mountain Syndicate, prospect of. ............... 79-80 

Lower Cambrian rocks, analyses of.................... 18 

Lucas, F. A., fossils determined by.................... 20 

Lungwitz, E. E., on gold-bearing rocks in Guiana .. 149-150 

Lynch and O'Meara, development by.................. 93 

M. 

MacNamara prospects, description of. ............... 93,122 

location of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 

Madagascar, gold-bearing rocks in..................... 143 

Magma. See Granitic magma; Magmatic quartz. 

Magmatic quartz, gold in ............................ 142-156 

origination of metalliferous veins in, theory of .. 129-156 

vcinlets of, plate showing.......................... 100 

See also Metalliferous deposits; Granitic magma. 

Magpie prospect,description of. ....................... 88-89 

Maitland, A. G., on tin in pegmatite . . . . . . . . . . . . . . . . . . . 140 

Mammoth claim, description of. ....................... 93-94 

Map, geologic, of Silver Peak quadrangle ........... Pocket. 

Mary mine, description of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54-56 

genetic relations at................................ 120 

mineralization in ........ _____ ... ___ .... _________ . 111,118 

ores of.............................................. M 

production of................................... 35 

section of, figure showing. . . . . . . . . . . . . . . . . . . . . . 55 

Marble, occurrence of. ...... _. _ . _______ . _. __ . ____ - _ _ _ _ _ 39 

May mine, production of.. . . . . . . . . . . . . . . . . . . . . . . . . 35 

Maynard, G. M., on Drinkwater and Blair orcs ....... 3(}-37 

Mendenhall, W. C., on gold-bearing rocks in Alaska... 15-' 

Merriam, J. C., fossils determined by................ 20 

Merrill, G. P., on gold-bearing rocks in Mexico........ 1.5( 

Metalliferous deposits, classes of ..................... 122-123 

comparison of other ores and ................... 123-128 

concentration of. ................................ 138-141 

description of. ..................................... 34-97 

genetic relations of. ............................... 99-123 

conclusions on ............................... 122-123 

origination of in magmatic quartz, theory of. ... 129-15fi 

See also individual districts, mines, etc. 

Page. 

Metallographic province, existence of. ................ 14,128 

Mexico, gold-bearing rocks in.......................... 156 

Mineral Ridge district, gold mines of, descriptions of.. 36-59 

history of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 

limestone on, view of .. __ . __ .. _. _. _. __ . _ .. ____ . _... 108 

metalliferous ore, deposits of, genetic relations of. 99-120 

production of. ..................................... 11,35 

rocks of. ......................................... 9,10,11 

silver mines of, descriptions of ..................... 69-74 

Minerals, paragenesis of ............................. 129-130 

Minerals, nonmetalliferous, deposits of .............. 157-168 

Mineralization, character of. ................. 13,109,110-111 

origin of............................... 13 

progress of. ......................... 11-12,13,108,109-111 

Mines, descriptions of. ................................. 36-97 

history of. ......................................... 10-11 

production of...................................... 11 

Mining, history of. .................................... 34-35 

Mispickel, occurrence of. .. _ _ ___ . _. _. _ .. _. ___ . _ 68 

occurrence of, sections showing ................... 67,68 

Missouri prospect, description of...................... 61 

Molybdenum in pegmatite, occurrence of . . . . . . . . . . . . . 141 

Montana, gold-bearing rocks in ...................... 154-156 

Monte Cristo Mountains, borax in..................... 161 

coal in............................................. 167 

Mountain Lion claim, description of. . . . . . . . . . . . . . . 96 

Mountain structure, description of. ................... 31-33 

Muscovite, character of. ................... 41,43,101,103,113 

crystal of, in orthoclase, plate showing............ 102 

origin of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41, 43, 107, 112-113 

N. 

Nevada Alpin0 mine, sections of, figures showing ..... 82,83 

Nevada claim, descriptwn of...................... 95 

Nevada metallographic province, occurrence and description of................................ 128 

New South Wales, Australia, gold-bearing rocks in ... 144-145 

Nome region, gold-bearing rocks in.................... !53 

N ordenskjold, Otto, on pegmatitic rocks.............. 136 

North America, gold-bearing rocks in ............... 151-156 

Norway, gold-bearing rocks in......................... 142 

Nova Scotia, gold-bearing rocks in.................... 151 

0. 

Officer, R. H., & Co., assays by .................. 38,49,50,97 

Olenollus gilberti, occurrence of. ....... __ .__ 17 

sp., occurrence of.._ ... ____________________________ 18 

Olenellus slates, distribution of........................ 18 

Ontario, gold-bearing rocks of.................. 123-124,151 

Ordovician rocks, description of..................... 17-19 

occurrence of.. _. __ . _ ............ _ . _ .. _ . _ . __ ... _ . _ 9 

Ores, analogies of. ... __ . _ . __ . __ .. _ ... _ ... _ ........ _. _ 13 

deposits of, form of.............................. 109 

form of, figure showing........................ 109 

description of. ..................................... 11-13 

origin of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 

See also particular mines, districts, etc. 

Outline of paper. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-15 

P. 

Paleozoic limestones, description of............ 17-19 

occurrence of.. __ ...... -. -- _ - -- -- --- --. -- -- -- _ 9 

Palmetto Company's prospect, description of... 74 

Palmetto district, description of. .................. 92-96,122 

prospects in ........................................ 35,93 

veins of . . ___ . ___ . __ .. _ . _. _. _ . _ . _ . _ . _ _ . -.. -. -. . . 13 

Palmetto Mountains, prospects on ................. !.1,35,92 
INDEX. 173 

Page. 1 

Pavmaster mine (Lone Mountain district), descrlp- 1 

-~~~:i~~-:~~:;~~-;·~~:L:i~~:: ::.:::.::::::: ::· ::::::: 73,1~~ i 

vie'v of_ ..... _ ...... _ ... _ ... __ ..................... . 

Paymaster prospect (Palmetto district), description 

ws 1 

of. ........................................ - 96 

history of. ................................... _.-._. 35 

Paymaster zone, prospects on, description of. ......... 95-96 

Pegmatite, concentration of metals in ............. -_ 138-141 

magnetic origin of. _ ........................... _. 130-13R 

Pegmatitic quartz in feldspar, plate showing.......... 42 

Penfield, S. L., on iron in pegmatite.................. 138 

Phillips and Lewis, on gold in Australia............... 144 

on Transvaal gold._......................... 143 

Phyllocarida, occurrence of............................ 18 

Pirrson, L. V ., on granitic rocks .. _ .. __ ..... _.......... 137 

Planorbis spectabilis, occurrence of .. __ 20 

utahensis, occurrence of. _ .. _ . ___ . __ . . . . . . . . . . . . . . . 20 

sp., occurrence of. ........ _........................ 20 

Playa, deposits of, analyses of..................... 159 

deposits of, description of.._ ................. 30,158-159 

occurrence of. ............................. 30,160-165 

view of......................................... 30 

Pleistocene deposits, occurrence and character of.. 10,29-30 

Pocatello mine, description of ....... __ ... . ..... 69-71 

mineralization in ............................ 118-119,120 

ores of. .. _........................ 69-71,118.119-120 

production of..................... . ........ -.- 35 

sections of, figures showing. _____________ -·- ___ ---- 69,70 

Porto Rico claim, description of....................... 96 

Production, value of.._ ............................ - 11,35-36 

See also particular mines. 

Prospects and mines. See Mines. 

Purington, C. W., on gold-bearing rocks in Appalachians ________________________ _ 

Pyrite in alaskite, plate showing ..................... . 

Q. 

153 

102 

Quartz, concentration of metals in......... 138-141 

magmatic origin of. ...... _ ...................... 130-138 

plate showing............................. 116 

occurrence of. ........ ___ .. _ .. __ .. __ ............ Passim. 

views of. ........................ 46,48,98,100,104,106,116 

segregations of alaskite and, plates ::showing . ___ .. 98 

See also Quartz, auriferous; Magmatic quartz. 

Q.uartz, auriferous, assay of. .... __ .. __ ..... _ ... _ ..... _ 38 

description of. .................................. 11,37-38 

genesis of. .............................. -.......... 14 

gold in, occurrence of. __ . _ . __ . _ .. __ .... _ .......... _ 99 

lens of, forking of, figure showing.................. 109 

lenses of, figure showing ...... _ .. __ .... _ .. ___ ..... _ 45 

liquid inclusions in ........ _._ ........ -............. 99 

occurrence of. ........ ___ .. ____ .. _________ .. -- .. Passim. 

relations of alaskitc and ............. 14,44-47,99-101,103 

values in ..................................... 37-38,50,99 

Quartz, pegmatitic, in feldspar, plate showing........ 42 

Quaternary detritus, occurrence and description of. ... 29-31 

Queensland, Australia, gold-bearing rocks in .. _ ... _... 144 

R. 

Rabbit Hole sulphur mine, ore of. ...... -.............. 157 

Ransome, F. L., on albite .. _ .... _..................... 127 

Ray, rocks near ... _._._ ............... _ ............. -.. 20 

Red Light mine, description of. . _ .. _ .. _ ..... -......... 60-61 

ores of. ............................................ 60-61 

production of.._ ................ _ .......... _ ... _ .. _ 60 

• Page. 

Red Monster mine, description of. ......... _. _.. . . . . . . . 66 

ores of. ..................... _ ... _.................. 66 

production of. ...................... _. . . . . . . . . . . . . . 35 

Reliance claim, description of. ___ ... _ .. ____ . ___ . ___ ... _ 95 

Rhodes marsh, borax in............................... 160 

Rhyolite, alum in. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Jj8 

intrusion by, figure showing....................... 166 

Richmond Chief prospect, description of .............. 89-90 

Richmond claim, description of_. _____ ._._. ___ . ___ ._ 96 

Robison Brothers, development by ..... _.......... 34 

Rocks, igneous, occurrence and description of._ .. __ 22-29 

Rocks, pre-Tertiary, occurrence and description of. ... 22-27 

Rocks, stratified, descriptions of. ... _ ................. 17-21 

intrusion in ...................................... 108-114 

Rose, E. H., location by .................... _.......... 96 

Rosen busch, H., on crystallization._._ .... __ ... __ ..... 130 

s. 

Salix an gust a., occurrence of. ........... __ .. __ ... _ ... _. 20 

Salt, deposits of, description of. .. _ ....... _._ ........ 158-159 

genesis of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160-165 

occurrence of. ........................... _ ......... _ 158 

relations of, to other deposits ... _................. 160 

Salterella sp., occurrence of. .............. _............ 18 

San Antonio marsh, borax in ..... _. ______ .. ___ .. __ .. 1.58--1.19 

Sand dunes, gold in.................................... 97 

occurrence and description of. .................. 30-31,96 

origin of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96-97 

Sassolite, occurrence of.._._. __ . __ ._._ .. _ ... _ ... __ . 162 

Scheerer, T., on crystallization._ ... ___ .. _ .... ___ .. __ 130-131 

on pegmatites...................................... 131 

Schrader and Brooks, on gold-bearing rocks in Alaska. 153 

Schuchert, C'harlcs, fossils determined by.............. 19 

Searles rnarsh, deposits in. __ .... _ .. __ . _____ ... __ .. __ 164--165 

Selwyn-Brown, A., on gold in Australia............... 145 

Sericite. See Muscovite. 

Siberia, gold-bearing rocks of.......................... 145 

Sierra Nevada, intrusions in .... __ .. __ ... __ ... __ ..... __ 31 

Silver, deposits of, description of. .. __ ._ .. _ .... _. 12,69-74,85 

genetic relations of. .............................. 118-120 

history of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-11 

rnincs of, description of. .. _ ......... __ .. ____ ... _. __ 69-74 

production of. ... _ ................................ _ 35 

See also particular mines. 

Silver Peak, view oL .. _ .... -.... _ .. ___ ..... __ .... __ .... 26 

rocks at and near.................................. 9,18 

Silver Peak district. See Mineral Ridge district. 

Silver Peak flat, wash apron at, view of. .... _ .. _ .. _.. 28 

Silver Peak Range, apron at, view of.- .... __ ..... _. __ . 28 

coal fields at, view of._ .. _......................... 166 

coal it1. _ .. ______ .... ___ .- ... ---- .. --- ... ____ ··---.. 35 

Silver Peak village, cone at, view of................... 26 

mill at............................................. 34 

Sinks, occurrence nnd description of_ ..... _._._ ... ___ .. 

Smith, --, borax development by __ ... _ .. ___ ...... _.. 160 

Smith, G. 0., on molybdenum in pegmatite........... 141 

Soda claim, description of. ..... -... -... -. _.. . . . . . . . . . . 61 

Sol berry mine, description of. ....... _._. __ ..... _...... 00 

ores of. .... _ .................... _. _.. . . . . . . . . . . . . . . 60 

production of._ .. _ ................................. 35,60 

Solutions, granitic, deposition by ...... _ .. _ ... _._ .. _... 12 

Sorhy, H. C., on liquid inclusions...................... 114 

South America, gold-bearing rocks in. __ . __ .. _._ .... 145-151 

South Carolina, gold-bearing rocks in ...... _._._ ... _.. 153 

South Dakota, gold-bearing rocks in ..... ··-·-·-·····- 156 

Spencer, A. C., on copper in pegmatite ..... __ ......... 139 

on iron in pegmatite ... _. . . . . . . . . . . . . . . . . . . . . . . . . . . 138 
174 INDEX • 

., Page. 

Sphalrium idahoense, occurrence of. . . . . . . . . . . . . . . . . . . . 20 

sp., occurrence of .... _____ ........ __ ------- .. _ .. __ . 20 

Springs, hot, deposits- by ......................... 14, 161-Hi2 

occurrence of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161 

Spurr, J. E., fossils collected by....................... 20 

on gold-bearing rocks in Alaska .............. 14,129,152 

on granitic rocks.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136, 138 

on iron ih pegmatite ............................. 138-139 

Steamboat Springs, cinnabar at ..................... 158,164 

Steiger, George, analyses by .......... 18, 23, 24, 26, 28, 159, 166 

Stetefeldite, occurrence of. ........................ 12, 120, 121 

Stoneham, "\V. J., on Elder-!1organ coal mine.-------- 167 

Storms, "\V. H., on rocks near Daggett._. __ ... _ ... _ 21 

Stratified rocks. See Rocks, stratified. 

Strephochetus sp., occurrence of_ ... _ ... __ ... _ .... _ _ 17 

Structure, mountain, description oL ... _ .. ___ .. __ ..... 31-33 

Sulphur, occurrence and description of_ .. __ .. 147 Hi7-158, 167 

Sultana mine, Ontario, description of ........... 123-124, 151 

T. 

Page. 

Vanderbilt mine, mineralization in .............. 118-119,120 

ores of ................................. 71-73.ll8, 119-120 

production of...................................... 35 

sections of, figures showing........................ 72 

Veatch, J. A., borax discovered by .................. 160, 163 

Vega mine, description of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65-66 

ores of............................................. 65 

production of. ..................................... 3.5, 65 

sections of, figures showing . .................. _ . . . . 65 

Veins, types of ......................................... 86-87 

Victoria, Australia, gold-bearing rocks in ........... 143-144 

Vivipara couesi, occurrence of. . ................... _ .. _ 20 

Vogt, J. H. L., on boron............................... 162 

on gold-bearing rocks inN orway.................. 142 

Volcanic activity, prevalence of........................ 19 

recency of. . . . . . . . . . .. . . . . . . . . . . . . . . . . . .. . . . . . . .. . . . 27 

Vollmar, F. A., assays by_ ...................... 38, 49,,10,97 

on sand dunes..................................... 97 

w. 

":real marsh, borax in .. _ .... _ ............... _ .... . 160 Walcott, C. D., fossils determined by.................. 17 

Telemarken, Norway, gold-bearing rocks in._ ..... . 142 Wall rocks, nature of. ................................. 39-44 

Tertiary rocks, description of. ............. . 19-21 relations of. ....................................... 44-49 

occurrence of_ . . ___ . ___ . ___ .. __ .. ___ . . . . . . . . . . . . . . 9 

Tetragraptus, occurrence of................ 19 

Tietjen mines, map showing . . . . . . . . . . . . . 34 

Tin in pegmatite, occurrence of. ..................... 139-140 

Tonopah, lavas at, analogy of Silver Peak lavas to... 20 

lavas at, correhLtion of..................... 20-21 

veins of, origin of......................... 127 

Tonopah Treasury prospect, description of............ 80 

Toyabe Range, ore deposits of, description of......... 125 

Transvaal, gold-bearing rocks of...................... 143 

Trilobites, occurrence of............................... 18 

Tungsten in pegmatite, occurrence of.................. 140 

Tumer, II. W., fossils collected by..................... 20 

minerals found by....................... 80 

on Can1brian-Ordovician rocks .................... 18-19 

on coal............................................. 166 

on faulting and folding............................ 29 

on Good Hope prospect............................ 85 

on granitic rocks . . _ .. __ ........................... 22, 136 

on greenstone. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . .. 26 

on pla.ya deposits ................................ 158-159 

on Quaternary Uepu.sits............................ 29 

on structure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 

on Tertiary rocks .......... : .................... 19,27-28 

work of............................................ 17 

u. 

Unio sp., occurrence of................................ 20 

United States, gold-bearing rocks in ................ 153-156 

Uplift, occurrence of. ............................. _ ... . 

Ural Mountains, gold-bearing rocks in ....... _ .. __ ... _ 

Utopia mine, description of._ ... _ .... _ ................ . 

sections of, figures showing ....................... . 

v. 

10 

142 

76 

76,77 

values in.......................................... 49-50 

\.Yaller, G. A., on granitic rocks ...................... 13fJ-137 

Wash aprons, views oi. ............................... _ 28 

Washington, H. 8., on granitic rocks.................. 137 

"'.,.asson, Samuel, on Drinkwater ores ................. 37-38 

"\Vaters, ascending, mineralization by._............... 12 

Weed, W. II., on gold-bearing rocks in Montana .... 155-156 

Weeks, ·F. B., fossils collected by....................... 17 

Weepah mines, description of. ......................... 80-81 

genetic relations at. . . . . . . .. . .. . . . . . . . . . . . . . . . . . . . . 120 

ores of. .................................... 80, 81, 120-121 

production of............................. 80 

'\Vestern Soldier mine, description of. ................. 52-53 

location of, figure showing......................... 52 

mineralization in . .. _ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 

ores of. . . . . .. . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . 52 

production of...................................... 52 

'Vhite Mountain Range, streams from. . . . . . . . . . . . . . . . 30 

Whitney, J.D., on Sierra Nevada..................... 126 

Widow Prospect, description of....................... 92 

section of, figure showing.......................... 93 

Wi!liams, G. H., on pegmatites........................ 135 

Wilson, G. B., on Chinese mines.................. 145 

Windypah district, deposits of, description of... 87-92,117 

description of....................... . .. 11, 8,';-86 

genetic relations in.................... . .... 121-122 

prospects in ..................................... 11,34-35 

rocks in. . . .. .. . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . 12, 85-86 

veins of. ..................................... 12-13,86-87 

Woitschach, Georg, on pegmatites............ 132 

Y. 

Yukon district, gold-bearing rocks in ............. 14,129, 152 

z. Vail IIise, c. R., on pegmatites .................. 135,137-138 

Vanderbilt mine, description of. ....................... 71-73 Zirkel, F., on liquid inclusions......................... 115 
CLASSIFICATION OF THE PUBLICATIONS OF THE UNITED STATES GEOLOGICAL SURVEY. 

[Professional Paper No. 55.] 

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 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. 

Most of the above publications may be obtained or consulted in the following ways: 

1. A limited number are delivered to the Director of the Survey, from whom they may be 

obtained, free of charge (except classes 2, 7, and 8), on application. 

2. A certain number are delivered to Se~ators and Representatives in Congress for distribution. 

3. Other copies are deposited with the Superintendent of Documents, ·washington, D. C., from 

whom they may be had at practically cost. 

4. Copies of all Government publications are furnished to the principal public libraries in the 

large cities throughout the United States, where they may be consulted by those interested. 

The Professional Papers, Bulletins, 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, 'Vater storage; K, Pumping water; L, Quality of water; M, General hydrographic investigations; N, Water power; 0, Underground waters; P, Hydrographic progress reports. This paper 

is the seventy-seventh in Series A, the ninety-sixth in Series B, and the thirty-third in Series D, the 

complete lists of which follow (PP=Professional Paper; B=Bulletin, WS= Water-Supply 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. (Out of stock.) 

B 46. Nature and origin of deposits of phosphate of lime, by R. A. F. Penrose, jr., with introduction by N. 8. Shaler. 1888. 

143 pp. (Out of stock.) 

B 65. Stratigraphy of the bituminous coal field of Pennsylvania, Ohio, and West Virginia, by I. C. White. 1891. 212 pp., 

11 pls. (Out of stock.) 

B 111. Geology of Big Stone Gap coal field of Virginia and Kentucky, by M. R. Campbell. 1893. 10 pp., 6 pis. (Out of 

stock.) 

B 132. The disseminated lead ores of southeastern Missouri, by Arthur Winslow. 1896. 31 pp. (Out of stock.) 

B 138. Artesian-well prospects in Atlantic Coastal Plain region, by N.H. Darton. 1896. 228 pp., 19 pls. 

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 J. 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. (Out of stock.) 

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

B 180. Occurrence and distribution of corundum in United States, by J. H. Pratt. 1901. 98 pp., 14 pis. (Out of stock; see 

No. 269.) 

B 182. A report on the economic geology of the Silverton quadrangle, Colorado, by F. L. Ransome. 1901. 266 pp., 16 pls. 

(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. 64 pp., 10 pls. (Out of stock.) 

B 193. The geological relations and distribution of platinum and associated metals, by J. F. Kemp. 1902. 95 pp., 6 pis. 

H 198. The Berea grit oil sand in the Cadiz quadrangle, Ohio, by W. T. Griswold. l902. 43 pp., 1 pl. (Out of stock.) 
II SERIES LIST. 

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. 

B 200. Reconnaissance of the borax deposits of Death Valley and Mohave Desert, br J\L R. Campbell. 1902. 23 pp., 1 pl. 

(Out of stock.) 

B 202. Tests for gold and silver in shales from western Kansas, by Waldemar Lindgren. 1902. 21pp. (Out of stock.) 

PP 2. Reconnaissance of the northwestern portion of Seward Peninsula, Alaska, by A. J. Collier. 1902. 70 pp., 11 pls. 

PP 10. Reeonnais~ance from Fort Hamlin to Kotzebue Sound, Alaska, by way of Dall, Kanuti, Allen, and Kowak rivers, 

by \Y. C. ~!endenhall. 1902. 68 pp., 10 pls. 

PP 11. Clays of the United States east of the 1\fississippi River, br Heinrich Ries. 1903. 298 pp., 9pls. 

PP 12. Geology of the Globe copper district, Arizona, by~-. L. Ransome. 1903. 168 pp., 27 pis. 

B 212. Oil fields of the Texas-Louisiana Gulf Coastal Plain, by C. W. Hayes and William Kennedy. 1903. 174 pp., 11 pls. 

(Out of stock.) 

B 213. Contributions to economic geology, 1902; S. F. Emmons and C. W. Hayes, geologists in charge. 1903. 449 pp. (Out 

of stock.) 

PP 15. The mineral resources of the Mount Wrangell district, Alaska, by W. C. Mendenhall and F. C. Sehmder. 1903. 

71 pp., 10 pis. 

B 218. Coal resources of the Yukon, Alaska, by A. J. Collier. 1903. 71 pp., 6 pis. 

B 219. The ore deposits of Tonopah, Nevada (preliminary report), by J .. K Spurr. 1903. 31 pp., 1 pl. (Out of &tock.) 

PP 20. A reconnaissance in northern Alaska in 1901, by F. C. Schrader. 1904. 139 pp., 16 pls. 

PP 21. Geology and ore deposits of the Bisbee quadrangle, Arizona, by F. L. Ransome. 1904. 168 pp., 29 pis. 

B 223. Gypsum deposits in the L:nitcd States, by G. I. Adams and others. 1904. 129 pp., 21 pis. 

PP 24. Zinc and lead deposits of northern Arkanslts, by G. I. Adams. 1904. 118 pp., 27 pis. 

PP 25. Copper deposits of the Eneampment district, Wyoming, by A. C. Spencer. 1904. 107 pp., 2 pis. 

B 225. CoBtributions to economic geology, 1903, by S. F. Emmons and C. W. Hayes, geologists in charge. 1904. 527 pp., 

1 pl. (Out of stock.) 

PP 26. Economic resonreeH of the northern Black HillA, by J.D. Irving, with contributions by S. F. Emmons and T. A. 

Jaggar. jr. 1904. 222 pp., 20 pis. 

PP 27. A geological rcconnaisRancc ncros~ the Bitterroot Range and Clearwater Mountains in Montana and Idaho, by 

\V alderrutr Lindgren. 1904. 123 pp., 15 pls. 

B 229. Tin deposits of the York region, Alaska, by A. J. Collier. 1904. 61 pp., 7 pis. 

B 236. The Porcupine placer district, Alaska, by C. W. Wright. 1904. 35 pp., 10 pls. 

B 238. Economic geology of the lola quadrangle, Kansas, by G. I. Adams, Erasmus H>tworth, and W. J:. Crane. 1904. 

83 pp., 11 pis. 

B 243. Cement materials and industry of the United States, by E. C. J<;ckel. 1905. 395 pp., 15 pis. 

B 246. Zinc and lead deposits of northwestern Illinois, by H. Foster Bain. 1904. 56 pp .. 5 pis. 

B 247. The Fairhayen gold placers of Seward Pcninwla, Alaska, by F. H. 1\Ioftit. 1905. 85 pp., 14 pis. 

B 249. Limestones of southeastern Penmylvania, by F. G. Clapp. 1905. 52 pp., 7 pis. 

B 250. The petroleum fields of the Pacific coast of Alaska, with an account of the Bering River coal deposg ·, by G. C. 

1\lartin. 1~03. 6o pp., 7 pis. 

B 251. The gold placers of the Fortymile, Birch Creek, and Fairbanks regions, Alaska, by h :\I. Prindle. 1905. ~9 pp.,16 pis. 

WS 117. The lignite of Korth Dakota and its relation to irrigation, by F. A. Wilder. 1905. 59 pp., 8 pis. 

pp 36. The lead, zinc, and fluorspar deposits of western Kentncky, by E. 0. Ulrich t1ml W. S. T. Smith. 1905. 218 pp., 15 pis. 

pp 38. Economic geology of the Bingham mining district, Utah, by J. 1\I. Boutwell, with a chapter on areal!);. >logy, by 

Arthur Keith, and an introduction on general geology, by S. F. Emmons. 1905. 413 pp., 49 pis. 

pp 41. Geology of the central Copper ltiver region, Alaska, by W. C. Mendenhall. 1905. 133 pp., 20 pis. , 

B 254. Report of progress in the geological resurvey of the Cripple Creek district, ColorDdo, by \Valdemar Lint.igren and 

F. L. Ransome. 1904. 36 pp. 

B 255. The fluorspar deposits of southern Illinois, by H. Foster Bain. 1905. 75 pp., 6 pis. 

B 256. Mineral resources of the Elders Ridge quadrangle, Pennsylvania, by R. W. Stone. 190:\. 86 pp., 12 pls. 

B 259. Report on progress of investigations of mineral resources of Alaska in 1904, by A. H. Brooks and othe, .. i. 1905. 

196 pp., 3 pis. · 

B 260. Contributions to economic geology, 1904; S. F. Emmons and C. W. Hayes, geologists in charge. 1905. 620 pp., 4 pis. 

B 261. Preliminary report on the operations of the coal-testing plant of the United States Geological Survey at the Louisiana. Purchase Exposition, St. Louis, ~Io., 1904; E. \Y. Parker, J. A. Holmes, and 1\.I. R. Campbell, committee in 

charge. 1905. 172pp. (Out of stock.) 

B 263. Methods and cost of gravel and placer mining in Alaska, by C. W. Purington. 1905. 273 pp., 42 pis. 

pp 42. Geology of the Tonopah mining district, Kcmda, by J. E. Spurr. 1905. 295 pp., 24 pis. 

pp 43. The copper deposits of the Clifton-Morenci district, Arizona, by Waldemar Lindgren. 1905. 375 pp., 25 p 

B 264. Record of deep-well drilling for 1904, by l\I. L. Fuller, E. F. Lines, and A. C. Veatch. 1905. 106 pp. 

B 265. Geology of the Boulder district, Colorado, by K. 1I. Fenneman. 1905. 101 pp., 5 pis. 

B 267. The copper deposits of Missouri, by H. Foster Bain and E. 0. Ulrich. 1905. 52 pp., 1 pl. 

B 269. Corundum and its occurrence and distribution in the United States (a revised and enlarged edition of BrUetin 

No. 180), by J. H. Pratt. 1906. 175 pp., 18 pis. 

pp 48. Report on the operations of the coal-testing plant of the United States Geological Survey at the Louisiana Purchase Exposition, St. Louis, Mo., 1904; E. W. Parker, J. A. Holmes, 1\1. R. Campbell, committee in charge. 1906. 

(In three parts.) 1,492 pp., 13 pis. 

B 275. Slate deposits and slate industry of the United States, by T. N. Dale, with sections by E. C. Eckel, W. F. Hillebrand, and A. T. Coons. 1906. 154 pp., 25 ,?Is. 
SERIES LIST. III 

PP 49. Geology and mineral resources of part of the Cumberland Gap coal field, Kentucky, by G. H. Ashley and L. C. 

Glenn, in cooperation with the State Geological Department of Kentucky, C. J. Norwood, curator. 1906. 239 .pp., 

40 p]R. 

B 277. Mineral resources of Kenai Peninsnla, Alaska: Gold fields of the Turnagain Arm region, by F. H. Moffit; Coal fields 

of the Kachemak Bay region, by R. W. Stone. 1906. 80 pp., 18 pis. 

B 278. Geology and coal resources of the Cape Lisburne re~ion, Alaska, by A. J. Collier. 1906. 54 pp., 9 pis. 

B 279. Mineral resonrces of the Kittanning and Rural Valley quadrangles, Pennsylvania, by Charles Butts. 1906. - pp., 

11 pis. 

B 280. The Rampart gold placer region, Alaska, by L.l\L Prindle and F. L. Hess. 1906. 54 pp., 7 pis. 

B 282. Oil fieldRof the Texas-Louisiana Gulf Coastal Plain, by N. M. Fenneman. 1906. 146 pp., 11 pis. 

PP 51. Geology of the Bighorn Monntains, by N. H. Darton. 1906. 129 pp., 47 pls. 

B 283. Geology and mineral resources of Mississippi, by A. F. Crider. 1906. 99 pp., 4 pis. 

B 284. Report on progress of investigations of the mineral resources of Alaska in 1905, by A. H. Brooks and others. 1906. 

169 pp., 14 pis. 

B 285. Contributions to economic geology, 1905; S. F. Emmons and E. C. Eckel, geologists in charge. 1906. 506 pp., 13 pis. 

D 286. Economic geology of the Beaver quadrangle, Pennsylvania, by L. H. Woolsey. 1906. - pp., 3 pls. 

B 287. Juneau gold belt, Alaska, by A. C. Spencer, and A reconnaissance of Admiralty Island, Alaska, by C. W. Wright. 

1906. 161 pp., 27 pis. 

PP 54. The geology and gold deposits of the Cripple Creek district, Colorado, by W. Lindgren and F. L. Ransome. 1906· 

- pp., 29 pis. 

PP 55. Ore deposits of the Silver Peak quadrangle, Nevada, by J. E. Spurr. 1906. 174 pp., 24 pis. 

SERIES B, DESCRIPTIVE GEOLOGY. 

B 23. Observations on the junction between the Eastern sandstone and the Keweenaw series on Keweenaw Point, Lake 

Superior, by R. D. Irving and T. C. Chamberlin. 1885. 124 pp., 17 pls. (Out of stock.) 

B 33. Notes on geology of northern California, by J. 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 pl. (Out of stock.) 

B 40. Changes in river courses in Washington Territory due to glaciation, by Bailey Willis. 1887. 10 pp., 4 pis. (Out of 

stock.) 

B 45. The present condition of knowledge of the geology of Texas, by ;a. T. Hill. 1887. 94 pp. (Out of stock.) 

B 53. The geology of Nantucket, byN. S. Shaler. 1889. 55 pp., 10 pis. (Out of stock.) 

B 57. A geological reconnaissance in southwestern Kansas, by Robert 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. Darton. 1890. 82 pp. (Out of 

stock.) 

B 104. Glaciation of the Yel!owstone Valley north of the Park, by W. H. Weed. 1893. 41 pp., 4 pis. 

B 108. A ,eological 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. 'l e geology of eastern Berkshire County, Massachusetts, by B. K. Emerson. 1899. 139 pp., 9 pis. 

B 165. Contributions to the geology of Maine, by H. 8. Williams and H. E. Gregory. 1900. 212 pp., 14 pis. 

W8 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. (,eology and water resources of the Snake River Plains of Idaho, by I. C. Russell. 1902. 192 pp., 25 pis. 

pp 1. 1 eliminary 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. i econnaissance 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 J. 8. Diller and H. B. Patton. 1902. 167 pp., 19 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. 

pp 13. Drainage modifications in southeastern Ohio and adjacent parts of West Virginia and Kentucky, by W. G. Tight. 

1903. 111 pp., 17 pis. 

B 2uo. 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. Daly. 1903. 122 pp., 7 pis. 

WS '18. 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, Alaska, 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 west of the one hundred and third meridian, 

by N.H. Darton. 1903. 69 pp., 43 pis. 

B 217. Notes on the geology of southwestern Idaho and southeastern Oregon, by I. C. Russell. 1903. 83 pp., 18 pis. 

B 219. The ore deposits of Tonopah, Nevada (preliminary report), by J. E. Spurr. 1903. 31 pp., 1 pl. 

13002--~o. 55--QB----12 
IV SERIES LIST. 

PP 20. A reconnaissance in northern Alaska in 1901, by F. C. Schrader. 1904. 139 pp., 16 pis. 

PP 21. The geology and ore deposits of the Bisbee quadrangle, Arizona, by F. L. Ransome. 1904. 168 pp., 29 pis. 

WS 90. Geology and water resources of part of the lower James River Valley, South Dakota, by J. E. Todd and C. M. Hall. 

1904. 47 pp., 23 pis. 

PP 2G. The copper deposits of the Encampment district, Wyoming, by A. C. Spencer. 1904. 107 pp., 2 pis. 

PP 26. Economic resources of the northern Black Hills, by J. D. Irving, with contributions by S. F. Emmons and T. A. 

Jagg•ir, jr. 1904. 222 pp., 20 pis. 

PP 27. A geological reconnaissance across the Bitterroot Range and Clearwater Mountains in 1\iontana and Idaho, by 

Waldemar Lindgren. 1904. 122 pp., 15 pis. 

PP 31. Preliminary report on the geology of the Arbuckle and Wichita mountains in Indian Territory and Oklahoma, 

by J. A. Taff, with an appendix on reported ore deposits in the Wichita Mountains, by H. F. Bain. 1904. 97 pp., 

8 pis. 

B 235. A geological reconnaissance across the Cascade Range near the forty-ninth parallel, by G. 0. Smith and F. C. 

Calkins. 1904. 103 pp., 4 p!H. 

B 236. The Porcupine placer district, Alaska, by C. W. Wright. 1904. 35 pp., 10 pis. 

B 237. Igneous rocks of the Highwood Mountains, Montana, by L. V. Pirsson. 1904. 208 pp., 7 pls. 

B 238. Economic geology of the Iola quadrangle, Kansas, by G. I. Adams, Erasmus Haworth, and W. R. Crane. 1904. 

83 pp., 1 pl. 

PP 32. Geology and underground water resources of the central Great Plains, by N.H. Darton. 1905. 433 pp., 72 pis. 

WS 110. Contributions to hydrology of eastern United States, 1904; M. L. Fuller, geologist in charge. 1905. 211 pp., 5 pis. 

B 242. Geology of the Hudson Valley between the Hoosic and the Kinderhook, by T. Nelson Dale. 1904. 63 pp., 3 pis. 

PP 34. The Delavan lobe of the Lake Michig•m Glacier of the Wisconsin stage of glaciation and associated phenomena, by 

W. c. Alden. 1904. 106 pp., 15·pls. 

PP 35. Geology of the Perry Basin in southeastern Maine, by G. 0. Smith and David White. 1905. 107 pp., 6 pis. 

B 243. Cement materials and industry of the United States, by E. C. }:ckel. 1905. 395 pp., 15 pis. 

B 246. Zinc and lead deposits of northeastern Illinois, by H. F. Bain. 1904. 56 pp., 5 pis. 

B 247. The Fairhitvcn gold placers of Seward Peninsulit, Alaska, by F. H. Moffit. 1905. 85 pp., 14 pis. 

B 249. Limestones of southwestern Pennsylvania, by F. G. Clapp. 1905. 52 pp., 7 pis. 

B 250. The petroleum fields of the Pacific coast of Alaska, with an account of the Bering River coal deposit, by G. C. 

Martin. 1905. 65 pp., 7 pis. 

B 251. The gold placers of the Fortymile, Birch Creek, and Fairbitnks regions, Alaskit, by L. 1\I. Prindle. 1905. 16 pp., 

16 pis. 

WS 118. Geology and water resources of a portion of east-central Washington, by F. C. Calkins. 1905. 96 pp., 4 pis. 

B 252. Preliminary report on the geology itnd witter resources of ceutral Oregon, by I. C. Russell. 1905. 138 pp., 24pls, 

PP 36. The lead, zinc, and fluorspar deposits of western Kentucky, by E. 0. Ulrich and W. S. Tangier Smith. 1905. 

218 pp., 15 pis. 

PP 38. Economic geology of the Bingham mining district of Utah, by J. M. Boutwell, with a chapter on areal geology, by 

Arthur Keith, and an introd.uction on general geology, by S. F. Emmons. 1905. 413 pp., 49 pis. 

PP 41. The geology of the central Copper River region, Alaska, by W. C. Mendenhall. 1905. 133 pp., 20 pis. 

B 254. Report of progress in the geological resurvey of the Cripple Creek district, Colorado, by Waldemar Lindgren and 

F .. L. Ransome. 1904. 36 pp. 

B 255. The fluorspar deposits of southern Illinois, by H. Foster Bain. 1905. 75 pp., 6 pis. 

B 256. Mineral resources of the Elders Ridge quadrangle, Pennsylvania, by R. W. Stone. 1905. 85 pp., 12 pis. 

B 257. Geology and paleontology of the Judith River beds, by T. W. Stanton and J. B. Hatcher, with a chapter on the 

fossil plants, by F. H. Knowlton. 1905. 174 pp., 19 pis. 

PP 42. Geology of the Tonopah mining district, Nevada, by J. E. Spurr. 1905. 295 pp., 24 pis. 

WS 123. Geology and underground water conditions of the Jornada del 1\fnerto, New Mexico, by C. R. Keyes. 1~05. 

42 pp., 9 pis. 

WS 136. Underground waters of Salt River Valley, Arizona, by W. T. Lee .. 1905. 194 pp., 24 pis. 

PP 43. The copper deposits of Clifton-Morenci, Arizona, by Waldemar Lindgren. 1905. 375 pp., 25 pis. 

B.265. Geology of the Boulder district, Colorado, by N. M. Fenneman. 1905. 101 pp., 5 pis. 

B 267. The copper deposits of Missouri, by H. F. Bain and E. 0. Ulrich. 1905. 52 pp., 1 pl. 

PP 44. Underground water resources of Long Island, New York, by A. C. Veatch and others. 1905. 394 pp., 34 pis. 

WS 148. Geology and water resourct's of Oklahoma, by C. N. Gould. 1905. 178 pp., 22 pis. 

B 270. The configuration of the rock floor of Greater New York, by W. H. Hobbs. 1905. 96 pp., 5 pis. 

B 272. Taconic physiography, by T. M. Dale. 1905. 52 pp., 14 pis. . 

pp 45. The geography and geology of Alaska, a summary of existing knowledge, by A. H. Brooks, with a section on cliirutte, 

by Cleveland Abbe, jr., and a topographic map and description thereof, by R.M. Goode. 1905. 327 pp., 34 pis. 

B 273. The drumlins of southeastern Wisconsin (preliminary paper), by W. C. Alden. 1905. 46 pp., 9 pis. 

pp 46. Geology and underground water resources of northern Louisiana and southern Arkitnsas, by A. C. Veatch.. 1906. 

422 pp., 51 pis. 

pp 49. Geology and mineral resources of part of the Cumberland Gap coal field, Kentucky, by G. H. Ashley and L. C. Glenn, 

in cooperation with the State Geological Department of Kentucky, C.J. Norwood, curator. 1906. 239 pp., 40 pis. 

pp 50. The Montana lobe of the Keewatin ice sheet, by F. H. H. Calhoun. 1906. 62 pp., 7 pis. 

B 277. Mineral resources of Kenai Peninsula, Alaska: Gold fields of the Turnagain Arm region, by F. H. Moffit, and the 

coal fields of Kachemak Bay region, by R. w. Stone. 1906. 80 pp., 18 pis. 

WS 154. The geology and water resources of the eastern portion of the Panhandle of Texas, by C. N. Gould. 1906. 

64 pp., 15 pis. 
SERIES LIST. v 

B 278. Geology and coal resources of the Cape Lisburne region, Alaska, by A. J. Collier. 1906. 54 pp., 9 pls. 

B 279. Mineral resources of the Kittanning and Rnral Valley quadrangles, Pennsylvania, by Charles Butts. 1906. - pp., 

11 pis. 

B 280. The Rampart gold placer region, Alaska, by L. J\I. Prindle and F. L. Hess. 1906. 54 pp., 7 pis. 

B 282. Oil fields of the Texas-Louisiawt Gulf coastal plain, by N. 1\L Fennemrm. 1906. 146 pp., 11 pis. 

WS 157. l:'nderground water in the valleys of Utah Lake and Jordan River, Utah, by G. B. Richardson. 1906. 81 pp., 9 pls. 

PP 51. Geology of the Bighorn Mountains, by~- H. Darton. 1906. 129 pp., 47 pls. 

WS 158. Preliminary report on the geology and underground waters of the Roswell artesian area, New Mexico, by C. A, 

Fisher. 190G. 29 pp., 9 pis. 

PP 52. Geology and underground waters of the Arkansas Valley in eastern Colorado, byN. H. Darton. 1906. 90 pp., 28 pls. 

WS 159. Summary of underground-water resources of Mississippi, by A. F. Crider and L. C. Johnson. 1906. 86 pp., 6 pis. 

PP 53. Geology and water resources of the Bighorn basin, Wyoming, by Cassius A. Fisher. 1906. 72 pp., 16 pis. 

B 283. Geology and mineral resources of Mississippi, by A. F. Crider. 1906. 99 pp., 4 pis. 

B 286. Economic geology of the Beaver quadrangle, Pennsylvania (southern Beaver and northwestern Allegheny counties), by L. H. Woolsey. 1906. - pp., 8 pis. 

B 287. The Juneau gold belt, Alaska, by A. C. spencer, and a reconnaissance of Admiralty Island, Alaska, by C. W. Wright. 

1906. 161 pp., 37 pis. 

PP 54. The geology and gold deposits of the Cripple Creek district, Colorado, by W~tldemar Lindgren and F. L. Ransome. 

1906. - pp., 29 pis. 

PP 55. Ore deposits of the Silver Peak quadrangle, Nevada, by J. E. Spurr. 1906. 174 pp., 24 pls. 

SERIES D, PETROGRAPHY AND MINERALOGY. 

B 1. On hypersthene-andesite anrl on triclinic pyroxene in augitic rocks, by Whitman Cross, with a geological sketch of 

Buffalo Peaks, Colomdo, by S. F. Emmons. 1883. 42 pp., 2 pis. 

B 8. On secondary enlargements of mineral fragments in certain rocks, Uy R. D. Irving and C. R. VanHise. 1884. 56 pp. 

6 pis. (On t of stock.) ' 

B 12. A crystallographic study of the thinolite of Lake L11hontan, by E. S. Dana. 1884. 34 pp., 3 pis. (Out of stock.) 

B 17. On the development of crystallization in the igneous rocks of Washoe, Nevada, with notes on the geology of the 

district, by Arnold Hague and J.P. Iddings. 1885. 44 pp. (Out of stock.) 

B 20. Contributions to the miner11Iogy of the Rocky Mount~tins, by Whitman Cross mul W. F. Hillebrand. 1885. 114 pp., 

1 pl. (Out of stock.) 

B 28. The gabbros and associ11ted hornblende rocks occurring in the neig-hborhood of Baltimore, Maryland, by G. H. 

Williams. 1886. 78 pp., 4 pis. (Out of stock.) 

B 38. Peridotite of Elliott County, Kentucky, by J. S. Diller. 1887. 31 pp., 1 pl. (Out of stock.) 

B 59. The g11bbros and associated rocks in Del~tware, by F. D. Chester. 1890. 45 pp., 1 pl. (Out of stock.) 

B 61. Contributions to the mineralogy of the Pacific coast, by W. H. Melville and Waldefnar Lindgren. 1890. 40 pp., 3 pis. 

(Out of stock.) 

B 62. The greenstone-schist areas of the Menominee and Marquette regions of Michigan; a contribution to the subJect of 

dynamic metamorphism in eruptive rocks, by G. H. Williams; with introduction by R. D. Irving. 1890. 241 pp. 

16 pis. (Out of stock.) 

B 66. On a group of volcanic rocks from the Tewan Mountains, New Mexico, and on the occurrence of primary quartz in 

certain basalts, by J. P. Iddings. 1890. 34 pp. 

B 74. The minerals of North C~trolina, by F. A. Genth. 1891. 119 pp. (Out of stock.) 

B 79. A late volcanic eruption in northern California and its peculiar lav11, by J. S. Diller. 1891. 33 pp., 17 pls. (Out of 

stock.) 

B 89. Some lava flows of the western slope of the Sierra Nevada, Californi~t, by F. L. Ransome. 1898. 74 pp., 11 pis. 

B 107. The trap dikes of the Lake Champl~tin region, by J. F. Kemp and V. F. MasterR. 1893. 62 pp., 4pls. (Out of stock.) 

B 109. The eruptive and sedimentary rocks on Pigeon Point, Minnesota, and their contact phenomena, by W. S. Bayley. 

1893. 121 pp., 16 pis. 

B 126. A mineralogical lexicon of Franklin, Hampshire, and Hampden counties, Massachusetts, by B. K. Emerson. 1895. 

180 pp., 1 pl. 

B 136. Volcanic rocks of South Mountain, Pennsylv~tnia, by Florence Bascom. 1896. 124 pp., 28 pis. 

B 150. The educational series of rock specimens collected and distributed by the United States Geological Survey, by J. S 

Diller. 1898. 400 pp., 47 pis. 

B 157. The .gneisses, gabbro-schists, and associated rocks of southwestern Minnesota, by C. W. Hall. 1899. 160 pp., 27 pis. 

PP 3. Geology and petrography of Cmter Lake National Park, by J. S. Diller and H. B. Patton. 1902. 167 pp., 19 pis. 

B 209. The geology of Ascutney Mountain, Vermont, by R. A. Daly. 1903. 122 pp., 7 pis. 

PP 14. Chemical~tn~tlyses of igneous rocks published from 1884 to 1900, with a critical discussion of the character and use 

of analyses, by H. S. W~tshington. 1903. 495 pp. 

PP 18. Chemical composition of igneous rocks expressed by means of diagrams, with reference to rock classification on a 

quantit~ttive chemico-mineralogical basis, by J. P. Iddings. 1903. 98 pp., 8 pis. 

B 220. Mineral analyses from the laboratories of the United States Geological Survey, 1880 to 1903, tabulated by F. w. Clarke, chief chemist. 1903. 119 pp. 

B 228. Analyses of rocks from the laboratory of the United States Geologic~tl Survey, 1880 to 1903, tabulated by F. w. Clarke 

chief chemist. 1904. 375 pp. 

PP 28. The superior analyses of igneous rocks from Roth's tabellen, 1869 to 1884, arranged according to the quantitative 

system of classification, by H. S. Washington. 1904. 68 pp. 
VI SERIES LIST. 

B 235. A geological reconnaissance across the Cascade Range near the forty-ninth parallel, by G. 0. Smith and F. C 

Calkins. 1904, 103 pp., 4 pis. 

B 237. Igneous rocks of the Highwood Mountains, Montana, by L. V. Pirsson. 1904. 208 pp., 7 pis. 

B 239. Rock cleavage, by C. K. Leith. 1904. 216 pp., 27 pis. 

B 241. Experiments on schistosity and slaty cleavage, by G. F. Becker. 1904. 34 pp., 7 pis. 

B 262. Contributions to mineralogy from the United States Geological Survey, by F. W. Clarke, W. F. Hillebrand, F. L. 

Ransome, S. L. Penfield, Waldemar Lindgren, George Steiger, and W. T. Schaller. 1905. 147 pp. 

PP 55. Ore deposits of the Silver Peak quadrangle, Nevada, by J. E. Spurr. 174 pp., 24 pis. 

Correspondence should be addressed to 

THE DIRECTOR, 

UNITED STATES GEOLOGICAL SURVEY, 

SEPTEMBER, 1906. WASHINGTON, D. c. 

0