DEPARTMENT OF THE INTERIOR

FRANKLIN K. LANE, Secretary

UNITED STATES GEOLOGICAL SURVEY

GEORGE OTIS SMITH, Director

Bulletin 652 4 "^

TUNGSTEN MINERALS AND DEPOSITS

BY

FRANK L. HESS

WASHINGTON

GOVERNMENT PRINTING OFFICE 

1917
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CONTENTS.

 Page. 

Introduction.............................................................. , 7

Inquiries concerning tungsten......................................... 7

Survey publications on tungsten........................................ 7

Scope of this report.................................................... 9

Technical terms...................................................... 9

Tungsten................................................................. H

Characteristics and properties........................................... n

Uses................................................................. 15

Forms in which tungsten is found...................................... 18

Tungsten minerals........................................................ 19

Chemical and physical features......................................... 19

The wolframites...................................................... 21

Composition...................................................... 21

Ferberite......................................................... 22

Physical features.............................................. 22

Minerals of similar appearance.................................. 24

Summary of characteristics.............. 1..................... 24

Distribution................................................... 24

Importance as an ore mineral................................... 25

Hubnerite....................:................................... 25

Physical features.............................................. 25

Minerals of similar appearance.................................. 26

Distribution................................................... 26

Importance as an ore mineral................................... 27

Wolframite........................................................ 27

Physical features.............................................. 27

Minerals of similar appearance........................... ^...... 28

Distribution.................................................. 28

Importance as an ore mineral................................... 2.9

Scheelite.............................................................. 29

Physical features.................................................. 29

Minerals of similar appearance...................................... 30

Summary of characteristics........................................ 31

Distribution...................................................... 31

, Importance as an ore mineral....................................... 32

CuprotungBtite....................................................... 32

Tungstite............!................................................ 33

Ferritungstite......................................................... , 34

Stolzite............................................................... 34

Raspite....................................'........................... 35

Tungsten deposits........................................................ 35

Associated rocks...................................................... 35

Distribution in the United States....................................... 36

3
4 . CONTENT'S.

Tungsten deposits Continued. . page.

Forme................................................................ 37

Segregation deposits.............................................. 37

Pegmatite dikes.................................................. 37

Veins............................................................ 39

Replacement deposits............................................. 40

Contact-metamorphic deposits....................................... 42

Placers.................; ......................................... 44

Tungsten veins....................................................... 45

Minerals......................................................... 45

Native elements.............................................. 45

Bismuth................... r ............................. 45

Gold..................................................... 45

Graphite................................................. 46

Sulphides, arsenides, antimonides, and tellurides................ 46

Arsenopyrite. ............................................... 46

Bismuthinite.............................................. 46

Chalcocite................................................ 46

Chalcopyrite.............................................. 47.

Cinnabar................................................. 47

Cosalite.................................................. 47

Covellite.................................................. 47

Galena.................................................... 47

Molybdenite.......................'........................ 47

Pyrite.. .....^........................................ *. 48

Silver minerals............................................ 48

Sphalerite...........:..................................... 48

Stibnite.................................................... 49

Sylvanite.................................................. 50

Calaverite ............................................... 50

Tetrahedrite.............. v-.............................. 50

Fluorides...................................................... 50

Oxides....................................................... 51

Cassiterite................................................. 51

Chalcedony. ............... ..........................'..... 51

Opal..................................................... 52

Quartz.................................................... 52

Hematite.................................................. 52

Carbonates.................................................... 53

Calcite, dolomite, ankerite, and siderite.................... 53

Silicates....................................................... 54

Feldspars................................................ 54

Beryl..................... *................................ 54

Chlorite.................................................. 54

Muscovite................................................ 54

Lepidolite................................................ 55

Topaz.......... ...................................a ...... 55

Tourmaline..............................:.......-...-..--. 55

Phosphates................................................... 56

Apatite.................................................... 56

Hamlinite (?).............................................. 56

Triplite. .1..................... ......................... 56

Minerals containing columbium and tantalum.................... 57
ILLUSTRATIONS. 5

Tungsten deposits Continued.

Tungsten veins Continued. Page.

Minerals found in tungsten-bearing pegmatites....................... 58

Outcrops of tungsten veins......................................... 59

Downward extent of tungsten veins................................ 61

Uneven distribution of tungsten in the veins......................... 63

Will tungsten deposits grow richer with depth?...................<s.. 64

Where to prospect for tungsten..................................... 65

Field tests for tungsten minerals............................................ 66

General instructions.................................................... 66

Necessary materials.................................................... 68

Approximate determination of percentage of tungsten in ores.................. 69

Quality of ore demanded by users.......................................... 73

Index................................................................... 81

ILLUSTRATIONS.

Page.

PLATE I. A, Wedge-shaped ferberite crystals from "Crow patent," Nederland, 

Colo.; B, Crystallized ferberite with elongated rhombic crystal 

faces, from Nugget mine, Gilpin County, Colo.-................... 22

II. A, Wedge-shaped ferberite crystals from Hoosier mine, Nederland, 

Colo.; B, Cuboid ferberite crystals from Georgia A. mine, Nederland. Colo...................................................... 23

III. A very fine specimen of ferberite with rhombic crystal faces, from

Nugget mine, Gilpin County, Colo.............................. 24

IV. A, Hiibnerite from Birdie mine, Butte, Mont.; B, Hubnerite from

Gladstone, near Silverton, Colo.................................. 24

V. A> Wolframite with cinnabar from Jack claim, Clark Mountains,

near Nipton, Cal.; B, Black hiibnerite from White Oaks, N. Mex... 24

VI. A, Cutand polished crystal of brown ferberite from Winnebago claim, 

"near Rollinsville, Colo.; B, Hubnerite crystals from Regan mining 

district, 35 miles north of Osceola, Nev............................ 26

VII. Wolframite crystals from Jack claim, Clark Mountains, near Nipton, 

Cal.: A, Wolframite crystal with rounded octahedra of scheelite 

perched upon it; B, Wolframite crystals, whose faces tend toward 

a square form, with rounded octahedra of scheelite ................ 27

VIII. Wolframite crystals from Zinnwald,.Bohemia...................... 28

I.. Large, imperfect crystals of wolframite embedded in quartz and

chalcopyrite, from Cornwall, England............................ 28

X. A, Scheelite from Papoose mine, Atolia, Cal.; B, Wolframite from

Wasp No. 2 mine, 2 miles south of Lead, S. Dak................. 30

XI. A, Scheelite with quartz, pyrite, and galena, from Golden Chest mine, 

Murray, Idaho; B, Scheelite with hiibnerite and quartz from vein 

4 miles north of Dragoon, Ariz.................................. 30

XII. A, Scheelite from Clifton mining district, Deep Creek Mountains, 

Tooele County, Utah; B, Scheelite and gray quartz from Kimberly- 

, Montana mine, Jardine, Mont................................... 30

XIII. A, Scheelite which has formed over a comb of wolframite and quartz, 

from Jack claim, Clark Mountains, near Nipton, Cal.; B, Scheelite 

with quartz and chlorite, from a contact-metamorphic deposit on 

Coming Power claim, 15 miles north of Lucin, Utah................. 30
ILLUSTRATIONS.

Page.

PLATE XIV. A, Scheelite with pyrite and quartz, from Breece Hill, Leadville, 

Colo.; B, Scheelite and quartz from Scheelite, 6 miles south of 

Osceola, White Pine County, Nev............................. 30

XV. .4, Stolzite from Broken Hill, New South Wales; B, Tungstite from 

Kootenay Belle mine, British Columbia; C, Scheelite stained 

with tungstite, from Yaqui River, Sonora, Mexico; D, Scheelite 

stained by iron, from Yaqui River, Sonora, Mexico; E, Scheelite 

with quartz in chlorite schist, from Moose River, Nova Scotia.. 30

XVI. Crystallized scheelite: A, B, Light-gray, slightly translucent specimens from Clifton mining district, Deep Creek Mountains, Tooele 

County, Utah; C, Specimen of reddish caramel color, translucent, from Tungsten, 12 miles south of Osceola, Nev.; D, 

Scheelite partly replaced by ferberite (reinite) and tungstite, 

from Kurasawa mine, Koshu, Japan ......................... 32

XVII. A, Cuprotungstite and .ferberite from Cave Creek, Ariz.; B, 

Scheelite being replaced by cuprotungstite, from Peelwood, New 

South Wales ............................................... 32

XVIII. A, Polished specimen of fine-grained pegmatite carrying wolframite, from Blue Grouse Mountain, Stevens County, Wash.; B, 

Polished specimen of pegmatite with ferberite, cutting granite, 

from Cave Creek, Ariz....................................... 38

XIX. Polished specimen from Humbug mining district, Yavapai

County, Ariz., showing anastomosing wolframite veinlets...... 39

XX. A, Part of a ferberite pebble from Nederland, Colo.; B, Scheelite 

pebble from Baltic Gulch, between Randsburg and Atolia, Cal.; 

C, Residual scheelite pebble coated with caliche (calcium carbonate), from Atolia, Cal.................................... 44

Hubnerite-bearing quartz vein in quartz-mica schist from Tungsten King mine, near Deer Park, Wash ........................ 45

A, Irregular masses of stibnite in quartz gangue of scheelite vein, 

Atolia, Cal.; B, Cavities formerly filled by slender crystals of 

stibnite, now partly filled by pinkish quartz, in quartz gangue 

of scheelite vein, Atolia, Cal................................ 50

XXIII. A, Hydrous iron oxide remaining after decomposition of ferberite 

from Good Luck claim, near Hill City, S. Dak.; B, Wolframite 

and cassiterite in quartz, from Black Metal claims, near Hill 

City, S.Dak............................................... 50

XXIV. A, Ferberite with fine-grained quartz having the appearance of 

chalcedony, from Conger mine, Nederland, Colo.; B, Polished 

specimen of scheelite with a thick crust of caliche (calcium 

carbonate), from Wickard mine, near Atolia, Cal.............. 52

XXV. Materials necessary for testing tungsten minerals ..............\... 68

FIGURE 1. Comparative sizes of a tungsten wire, a human hair, and a strand

of spider's silk.............................................. 13

2. Comparative efficiency in cutting steel of tungsten (high speed)

steel tools, and carbon steel tools............................. 16

3. Relation of tungsten veins to country rocks .................... 66

4. Curves showing the relations between the specific gravity of

tungsten ores and the percentage of contained W03 .... ^..... 72
TUNGSTEN MINERALS AND DEPOSITS.

By FRANK L. HESS.

INTRODUCTION.

INQUIRIES CONCERNING TUNGSTEN.

The United States Geological Survey daily receives numerous 

inquiries from people in many walks of life for information about 

tungsten. These inquiries come from school children who are writing essays; from prospectors who wish descriptions of tungsten 

minerals, a statement of the conditions under which they are found, 

and directions for testing the minerals; from owners of prospects 

or mines who want to know where ores may be sold and their prices 

and uses; arid from brokers, dealers, and consumers who desire to 

know in what parts of this and other countries tungsten ores are 

found and the quantities produced. Some wish to know where the 

manufactured metal may be obtained, some inquire how it is reduced, 

and some ask what tungsten is and desire other general information 

about it.

SURVEY PUBLICATIONS ON TUNGSTEN.

Questions concerning the quantities produced, localities of production, and uses and -tests for the minerals are considered in the chapter on tungsten in the volumes entitled " Mineral Resources of the 

United States," published annually by the United States Geological 

Survey, and some of the deposits in the United States have been 

described in other publications of the Survey. The papers listed 

below describe particular tungsten' deposits or groups of tungsten 

deposits. Those for which a price is given are for sale by the 

Superintendent of Documents, Washington, D. C. The others may 

be obtained free by applying to the Director of the Survey.

BANCROFT, HOWLAND, Notes on tungsten deposits near Deer Park, Wash.: Bull. 

430, pp. 214-216, 1910. 60c.

Describes, briefly, hiibnerite deposits which lie a fe\y miles northeast of 

Deer Park, Wash. The hiibnerite is accompanied by argentiferous cosalite 

(lead-bismuth sulphide) and some smoky quartz. Parts of the vein contain mica and orthoclase feldspar.

 ' The ore deposits of northeastern Washington: Bull. 550, pp. 29, 111-123, 

130-133, ills., 1914.
8 TUNGSTEN MINERALS AND DEPOSITS.

Describes the Germania wolframite deposit (known also, though not so 

mentioned in the report, as the " Cedar Canyon," " Deer Trail," and " Roselle" deposit) and the Tungsten King hiibnerite deposit near Loon Lake 

and Deer Park. The matter on pp. 130-133 is practically a reprint of theo 

article by the same author in Bulletin 430. In the Germania deposits a 

black wolframite is found in white quartz veins cutting granite and quartzmica schist. The wolframite is accompanied by considerable pyrite and a 

little arsenopyrite, galenobismutite, molybdenite, scheelite, and ferrotungstite. A very little silver and gold are also present. Some shipments of 

wolframite have been made.

HESS, F. L., Note on a tungsten-bearing vein near Raymond, Cal.: Bull. 340, 

p. 271, 1908. 30c.

A brief description of a wolframite-bearing quartz vein cutting schists 

near Raymond, Cal. The deposit is without economic value.

 -Tin, tungsten, and tantalum deposits of South Dakota: Bull. 380, pp. 

149-157, 1909. 40c.

Describes the pegmatites and pegmatitic quartz veins near Hill City, 

Oreville, and Keystone, which carry tungsten minerals; mostly wolframites. 

A very little scheelite accompanies the other tungsten minerals. Also describes the wolframite deposits which are associated with gold ores near 

Lead.

 Note on a wolframite deposit in the Whetstone Mountains, Ariz.: Bull.

380, pp. 164-165, 1909. 40c.

Describes a deposit of wolframite in the Whetstone Mountains, 12 miles 

southwest of Benson, which is apparently a segregation from granite.

HESS, F. L. and SCHALLER, W. T., Colorado ferberite and the wolframite 

series: Bull. 583, 75 pp., ills., 1914. 20c.

A detailed description of the mineralogy of ferberite, a consideration of 

the relations of the natural manganese-iron tungstates, and a comparison 

of analyses.

HILL, J. M., Note on the occurrence of tungsten minerals near Calabasas, Ariz.: 

Bull. 430, pp. 164-166, 1910. 60c.

Describes quartz veins carrying wolframite near Calabasas, 7 or 8 miles 

north and a little west of Nogales.

HOBBS, W. H., The old tungsten mine at Trumbull, Conn.: Twenty-second Ann. 

Rept, pt. 2, pp. 7-22, ills., 1901. $2.25.

 Tungsten mining at Trumbull, Conn.: Bull. 213, p. 98, 1903. Exhausted. 

Describes a deposit of scheelite (part of which is replaced by wolframite) 

in metamorphosed limestone in Long Hill, near Trumbull.

JOHNSON, B. L., Occurrence of wolframite and cassiterite in the gold placers of 

Deadwood Creek, Birch Creek district [Alaska] : Bull. 442, pp. 246-250, 

1910. 40c.

The gold-bearing gravels yield 1 to 2 pounds of concentrates to the 

cubic yard, consisting mostly of wolframite and cassiterite. Relative proportions are not given.

KNOPF, ADOLPH, Geology of the Seward Peninsula tin deposits, Alaska: Bull. 

358, pp. 38, 55-58, ills., 1908.

Gives a technical description of the occurrence of tungsten minerals in 

the tin-bearing regions of Seward Peninsula, Alaska. Scheelite is found in 

contact-metamorphic deposits on Cape Mountain, though not in commercially valuable quantity. Wolframite is found on Lost River with 

cassiterite and minerals characteristic of tin veins topaz, zinnwaldite, 

arsenopyrite, chalcopyrite, and others and less usual minerals, such as 

zinc blende and stannite. No production of tungsten has been made from 

the deposits.
INTRODUCTION. 9

KNOPF, ADOLPH, Tungsten deposits of northwestern Inyo County, Cal.: Bull. 

640, pp. 229-249, 1917 (Bull. 640-L).

Describes contact-metamorphic deposits in limestone intruded by granite. 

UMPLEBY, J. B., Geology and ore deposits of Lemhi County," Idaho: Bull. 528, 

pp. 73-74, 77, 79, 109-112, 2 ills., 1913.

Quartz veins carrying hiibnerite with copper minerals, siderite, molybdenite, and galena cut schists of Algonkian age.

WEEKS, F. B., An occurrence of tungsten ore in eastern Nevada: Twenty-first 

Ann. Kept., pt. 6, pp. 319-320, 1901.

 Tungsten ore in eastern Nevada: Bull. 213, p. 103, 1903. Exhausted.

 Tungsten deposits in the Snake Range, White Pine County, eastern 

Nevada: Bull. 340, pp. 263-270, 1908. 30c.

All three papers describe hubnerite-bearing quartz veins carrying also a 

,, little scheelite and gold, which cut granite on the west side of Wheeler 

Peak, 12 miles south of Osceola. These are the deposits now worked by 

the U. S. Tungsten Corporation at Tungsten.

WINCHELL, A. N., Mining districts of the Dillon quadrangle, Mont., and adjacent areas: Bull. 574, p. 125, 1914.

Describes the occurrence of hiibnerite in the Potosi district, 14 miles 

southwest of Pony, in veins cutting quartz monzonite that were formerly 

worked for silver. The hiibnerite is commonly confined to streaks 1 to 18 

inches thick, but a width of 20 inches was found on the Rockefeller claim, 

a sample from which assayed 4.5 per cent of tungstic acid. Hiibnerite is 

one of the later-formed minerals in the vein; quartz crystallized simultaneously with the tungsten, and thin layers of chalcedony formed afterward. 

Fluorite is common and varies remarkably in color, being purple, green, 

blue, white, or black. The veins grade into pegmatite at the Strawberry 

mine.

SCOPE OF THIS REPORT.

Tungsten minerals have been briefly described in several Survey 

publications other than those listed above, but it has been found that 

prospectors and others who are relatively untrained in the study of 

minerals can not positively identify them from descriptions alone; 

it is necessary to use also colored plates showing their appearance, 

such as are given in this bulletin. An attempt is made to gather into 

this bulletin the known general facts about tungsten, the minerals 

in which it is found, the kinds of deposits from which these minerals 

have been obtained, and other information which will answer as 

many as possible of the questions asked the Survey, and to show 

by illustrations, colored and uncolored, the appearance of typical 

specimens of the various tungsten minerals. The purpose has been 

to make this paper of interest and use to the prospector and miner, 

and also to those who have no particular knowledge of minerals.

TECHNICAL TERMS.

Technical words are avoided in this paper as far as may be, but 

many technical terms are merely names for things or properties that 

are themselves unfamiliar, the names being unfamiliar for the same 

reason. Ten years ago the word tungsten itself was strange to most 

well-read persons, and it is yet strange to many. A "technical"
10 TUNGSTEN MINERALS AND DEPOSITS.

\

word or expression belongs to some particular profession or trade. 

Miners and prospectors often speak of technical words as if they 

were used only, by professional or scientific men who wish to write 

above the comprehension of the ordinary reader. As a matter of 

fact, persons in all trades and callings necessarily use words that 

apply only to their work and that are therefore technical. The 

simpler the subject or the more superficially it is treated the fewer 

are the technical terms used, but the most ordinary occupations have 

such terms. Farmers " list" corn and " drill" wheat, and those who 

really study their soils and fertilizers and the plants they raise add a 

great number of new words to their vocabularies. Mining is a 

calling which deals with subjects unfamiliar to the majority of 

people and which has developed a large number of technical words, 

and many of the terms in common use among miners and prospectors 

are wholly foreign to others. Such words as moil, stope, winze, 

drift, adit, gouge, singlejack, shoes, and dies mean little or nothing 

to most persons not familiar with the working of mineral deposits. 

The jokes told in every mining camp at the expense of the newcomer who is mystified about " horses " in the veins need only be 

mentioned to give point to this statement.

Technical words are necessary to express definite ideas, and each 

has a specific meaning and usually only one meaning, so that it is 

much easier to write exactly with them than without them and thus 

to save time and effort in writing and to insure clearness in expression. To appreciate this fact it is only necessary to attempt to 

indicate the objects mentioned above "in common language," 

intelligible to any person who knows nothing of mines or mining. 

As the knowledge of ore deposits grows, many terms which only a 

short time ago were considered the special property of the professional geologist or mining engineer are finding their way into everyday talk. Such words as rhyolite, dacite, diorite, hiibnerite, alunite, 

and the chemical symbols for the rare and heretofore little-known 

minerals, all of which were, until the last few years, considered too 

technical for the ordinary man of the camp, have become or are fast 

becoming the common property of all 'miners and prospectors. 

Numerous letters received at the Geological Survey show that the 

prospector, by reading the technical periodicals and the reports of 

the State and national surveys and by studying textbooks, is making 

himself familiar with many of the less common phenomena of ore 

deposits and of general geology, and necessarily with the terms by 

which they are described.
TUNGSTEN MINERALS AND DEPOSITS. 11

TUNGSTEN. 

CHARACTERISTICS AND PROPERTIES.

Tungsten is a metallic element, like iron, gold, lead, copper, and 

other well-known metals. It is never found native but must be reduced from its ores to the metallic condition by artificial means. The 

metal tungsten as thus obtained is a gray powdery or granular mass, 

from which wrought or ductile tungsten can be made.

In the wrought or ductile form tungsten looks very much like iron 

or steel and takes a very similar polish. Its unpolished surface, 

however, shows none of the discolorations common to iron or steel. 

Owing to its color and to its freedom from tarnish tungsten has been 

proposed as a substitute for platinum in jewelry, but it is not so 

white and is very difficult to work. As commonly seen the wrought 

metal is nearly black, being coated, possibly, with a suboxide, just 

as the " lead-gray " color of lead is due to an oxide, though the metal 

itself is silvery white.

The tungsten mineral wolframite was known in the tin mines of 

the Saxony-Bohemia region, and later in Cornwall, long before the 

element itself was discovered. It is said that it was at first taken 

for a tin mineral but was later considered detrimental to the tin 

ores and to "eat" the tin. Agricola (1490-1555) believed the name 

to have come from the German words "wolf," the same as the 

English word, and "ram" or "rahm," froth. His works are written in Latin, and in them he gives lupi spuma as the equivalent of 

wolfram. Although this derivation seems plausible some deny it, 

holding merely that the origin is unknown.

In 1781 the Swedish chemist Scheele 1 discovered a new mineral 

acid in the stony mineral which was afterward named for him 

scheelite and the element thus discovered was later named tungsten, 

from the two Swedish words " tung," heavy, and " sten," stone. The 

original pronunciation was therefore "tungstane," ' the "u" being 

sounded as in " run" and the " a " as in " plane." The word has 

been anglicized so that the " e " is pronounced as in " pen." In Great 

Britain and its provinces the word " wolfram " has been compelled 

to do duty for both mineral and metal, but there is now a distinct 

trend to the better usage of calling the metal tungsten and the 

mineral wolframite.

In 1785 the D'Elhujar 2 brothers, Juan, Jose, and Fausto, found 

that wolframite also contained tungsten and established the relation

1 Scheele, K. W., K. svenska Vet.-Akad. Haridl., Stockholm, 1781. See following note.

2 A chemical analysis of wolfram and examination of a new metal which enters into its 

composition, translated from the Spanish by C. Cullen, to which is prefixed a translation 

of Mr. Scheele's analysis of the, tungsten or heavystone, with Mr. Bergmann's supplemental remarks, London, 1785. (This reference and the one preceding are taken from 

Roscoe, H. E., and Schorlemmer, C., A treatlse.qn chemistry, vol. 2, p. 1083, 1913.)
12 TUNGSTEN MINERALS AND DEPOSITS.

of scheelite to wolframite. They also succeeded in obtaining metallic 

tungsten from the oxide and were probably the first to reduce the 

metal from its compounds. The chemical symbol for tungsten most 

generally used is W, the first letter of a partly Latinized form of 

the name, wolframium, and probably no other chemical symbol, 

except 0 for oxygen, is so well known to prospectors and miners, 

for tungsten ores are sold, not on their metallic content figured as 

such, but on their content of WO3 , tungsten trioxide. The French 

more reasonably use Tu as the symbol for tungsten.

The atomic weight that is, the weight of the smallest quantity of 

the element capable of combining chemically with another element 

is 184, the weight of the oxygen atom being taken as 16.

The hardness of tungsten ranges from 4.5 (razor steel is about 6) 

to 8, depending on the manner in which it is worked. The hardest 

is as hard as topaz and will readily scratch quartz, yet it is ductile.

Tungsten is very heavy. Its specific gravity 1 ranges from 19.3 

to 21.4, depending on the mode of treatment of the metal. Fine wire 

has a greater density than the larger worked masses. The great 

weight of tungsten will be more apparent on comparing it with that 

of other and betterrknown metals. Thus, aluminum has a specific 

gravity of 2.7; iron, 7.8; copper, 8.9; lead, 11.4; and gold, 19.3; or, 

to put it another way, a piece of tungsten will weigh more than seven 

times as much as a piece of aluminum of the same size, 2£ times as 

much as iron, nearly twice as much as lead, and slightly more than 

gold. Only three known metals have a higher specific gravity than 

tungsten, namely, platinum, 21.5; iridium, 22.4; and osmium, 22.5.

The melting point of tungsten is higher than that of any other 

known metal. As determined by Langmuir,2 it is 3,267° C. (5,913° 

F.), a temperature so high that it is impossible to attain it in commercial furnaces in which at the same time the tungsten can be kept 

free from oxygen, carbon, or other impurities.

Tungsten seems to be naturally crystalline and brittle but has a 

considerable degree of elasticity when worked sufficiently. Like zinc, 

its structure is changed by working, but unlike zinc it thus develops 

great tensile strength, and it can be drawn into wire less than four 

ten-thousandths of an inch in diameter, a sixth to a fourth of the 

diameter of a hair from the head of an adult. (See fig. 1.) Tungsten wires are said to have a tensile strength fully equal to that of 

the best steel, but incandescent lamp filaments made from tungsten wire return to a crystalline condition after they have been used 

a short time unless the tungsten is alloyed with some other substance

1 The specific gravity of a substance is its weight as compared with that of an equal 

bulk of water at the temperature of greatest density (4° C.=39.29 F.). '

2 Langmuir, Irving, quoted by Fink, C. G.. in The mineral industry during 1914, p. 759, 

1915.
TUNGSTEN. 13

such as thorium. Tungsten, like iron, becomes much more malleable 

on being heated to a red heat or above. It is not magnetic. Some 

of the principal physical characteristics of tungsten, aluminum, copFIODBE 1. Comparative sizes of (a) a tungsten wire, 0.0004 inch (0.01 millimeter) 

thick; (6) a human hair, 0.003 inch (0.075 millimeter) thick; and (c) a strand of 

spider's silk, 0.0002 inch (0.005 millimeter) thick. Greatly magnified. From a photomicrograph.

per, nickel, and iron haye been set forth by Colin G. Fink 1 in the 

following table:

Physical properties of aluminum, copper, nickel, iron, and tungsten.

Nickel......................

Density 

at 18° 9.

2 7

8.87

8.75

. 7.8

19.6

Coefficient 

, of expansion at 

18° C. 

21. 8 by 10-8

15. 9 by 10-«

12. 7 by 10-«

11. 2 by 10-6

3. 5 by 10-«

Tensile 

strength 

in pounds 

per 

square 

inch.

43,000

66,000

96,000

450,000

610,000

Modulus 

of elasticity 

in pounds 

per square 

' inch.

. 10 by 10-6

19 by 10-8

29 by 10-6

30 by 10-6

60 by 10-8

Specific 

heat in 

calories, 

1 gram -1°C.

0.214

.091

.106

.105

.034

Melting 

point in 

f C.

660

1,083

1,453

1,600

3,267

'Electric 

resistance 

in 

microhms 

per cubic centimeter.

9 fi9

1.589

6.93

8.85

4.42

NOTE. The figures given for iron in the third and fourth columns are for high tensile strength steel. 

Of the figures for tungsten those showing the specific heat are given by Honda, those showing the melting 

point by Langmuir; the others were determined by Fink.

1 Fink, C. G., The mineral industry during 1914, p. 759, 1915.
14 TUNGSTEN MINERALS AND DEPOSITS.

Tungsten is an acid-forming element no mineral has been found 

in which it acts as a base; the important known salts of tungsten 

acid minerals are tungstates combined with other metals. Roscoe 

and Schorlemmer 1 give a list of 13 tungsten acids that have been 

artificially prepared, but salts of only one acid are known to occur 

in nature, those of H2W04 , the normal tungstic acid. The ordinary 

tungsten minerals, hiibnerite, ferberite, wolframite, scheelite, stolzite, 

raspite, and cuprotungstite, are salts of this acid combined with 

manganese, iron, lime, lead, and copper. Besides these tungstates 

there have been found only insignificant quantities of tungsten 

oxides. '

The metal is comparatively inert that is, it is not attacked by 

many of the elements and compounds which combine chemically 

with other metals. It remains almost unaffected by air or water at 

ordinary temperatures, but when heated in air above 300° C. it oxidizes rapidly to the yellow trioxide (W03 ) and burns brilliantly 

when heated to bright redness.

It is attacked by fluorine at ordinary temperatures, with incandescence, and by chlorine at 250°-300° C. but does not react with 

nitrogen and phosphorus at a red heat; when heated with carbon, 

silicon, or boron in the electric furnace it yields crystalline compounds 

having a metallic luster, which are hard enough to scratch rubies. 

It is slowly attacked by fuming sulphuric acid and by fused alkalies. 2 

It is slpwly attacked by water containing carbon dioxide; it is 

readily oxidized when heated with oxidizing agents, such as lead 

dioxide or potassium chlorate. Sulphuric, hydrochloric, and hydrofluoric acids act upon it slowly (Fink 3 adds to these nitric acid), 

but it is readily dissolved by a mixture of nitric and hydrofluoric 

acids; the powdered metal is rapidly oxidized by aqua regia and dissolves in boiling caustic potash solution with formation of potassium 

tungstate and evolution of hydrogen, whereas the fused metal is not 

attacked by aqua regia but dissolves slowly in fused potash (Stavenhagen). 4 °

Tungsten forms alloys with many,of the common metals, and probably half of the ores used in the United States are redjiced to ferrotungsten, an alloy of iron and tungsten, and sold in that form. With 

cobalt and chromium it forms one of the group of alloys known as 

stellite, which is used in cutting steel. Alloys with aluminum, copper, 

manganese, and nickel have been made but have not been extensively 

used.

1 Roscoe, H. B., and Schorlemmer, C., A treatise on chemistry, vol. 2, p. 1087, 1913.

2 Reader, W. B., Solubility of wrought tungsten and molybdenum: Am. Chem. Soc. 

Jour., vol 3'4, pp. 387-388, 1912.

3 Fink, C. G., Ductile tungsten and molybdenum : Am. Electrochem. Soc. Trans., vol. 17, 

p. 233, 1910.

4 Roscoe, H. E., and Schorlemmer, C., op. cit., p. 1085.
' TUNGSTEN. 15

Besides the alloys named, various compounds 1 with, ammonium, 

arsenic, barium, boron, bromine, cadmium, carbon, chlorine, chromium, cobalt, fluorine, iodine, lithium, magnesium, mercury, molybdenum, phosphorus-, potassium, silicon, silver, sodium, strontium, 

thorium, tin, vanadium, zinc, and zirconium have been formed artificially, but none, with the exception of one compound with molybdenum, have been found as minerals.

When treated with hydrochloric acid the tungsten compounds found 

in nature give up, though not always readily, the metals with which 

they are combined and leave the yellow tungsten trioxide (W03 ), 

and on adding zinc or tin to the acid solution, thus generating hydrogen, the yellow trioxide gives up a part of its oxygen and becomes the 

blue oxide (W2 0B ), which on further reduction gives purple and 

brown compounds containing less oxygen. This forms the commonest and easiest test for tungsten and will be treated elsewhere 

(pp. 66-67).

On being heated in an atmosphere of hydrogen the yellow oxide is 

reduced through the lower oxides to the metal, and this process is 

utilized in producing pure tungsten.

USES.

The greatest use of tungsten, a use that overshadows all others in 

the quantity of the metal utilized, is as a constituent of tool steels, 

especially of those known as " high-speed " steels. Of these steels 

as they are made in this country it forms percentages ranging from 

13 to 20. Some European steels are said to contain still higher percentages, but the consensus of opinion among American makers is 

that the use of more than 20 per cent of tungsten in steel is practically 

valueless. High-speed tungsten steels have increased the efficiency 

of both machinists and lathes tremendously, and manufacturers 

working large groups of men say that from three to five times as 

much metal can be cut with such a steel as with the old simple carbon 

steel. In other words, under favorable conditions one man and one 

lathe can do as much work with high-speed tungsten steels as five 

men and five lathes could formerly do with simple carbon steels. 

(See fig. 2.)

Hundreds of millions of dollars' worth of labor is saved annually 

through the use of high-speed steels, and it would doubtless have 

been impossible to make the great quantities of turned and cut steel 

manufactured in this country in 1916 if it had been necessary to 

revert to the use of carbon steels. A striking statement of the results 

of this efficiency of high-speed steel was given to the Survey in 1911

1 Heinrich Leiser, in his " Wolfram, eine Monographic mit einem Anhang, Die Patentanspriiche uber Wolfram-Gltihkb'rper," published at Halle an der Saale in 1910, has made 

an extensive compilation ofothe chemical compounds of tungsten. See also Roscoe, I-I. E., 

and Schorlemmer,' C., A treatise on chemistry, vol. 2, pp. 1082-1104, 1913, and Thorpe, 

Edward, A dictionary of applied chemistry, vol. 5, pp. 566-571, 1912-13.
16 TUNGSTEN MINEEALS AND DEPOSITS.

by Mr. Elwood Haynes, of the Haynes Automobile Co., who said that 

his company would be compelled to add $200 to the selling price of 

each automobile it produced if it should have to use carbon-steel 

tools in place of the high-speed tools which it then employed.

The value of high-speed tungsten steel depends not. only on its 

greater hardness but on its quality of holding its hardness when 

heated to dull redness. This quality allows the tool to cut other 

metal at a rate which heats the point to about 535° C. (1,000° F.). 

Carbon steels fail long before they reach this temperature. This 

property of holding its temper while heated may be due to carbides 

of tungsten formed in the steel by the combination of the tungsten 

and carbon of the alloy, the steel proper being merely a medium that 

holds the tungsten carbide, which is harder than any known natural 

substance except diamond.1

PIGDBE 2. Comparative efficiency in cutting steel of high-speed tungsten-steel tools and 

carbon-steel tools. Under favorable conditions the tungsten steel cuts five times as fast 

as the carbon steel.

High-speed tungsten steels are very complicated alloys, and, as 

would be expected of a compound containing so many elements, there 

is necessarily much uncertainty as to the value of each element, so 

that the composition of the steels varies with the maker. The following analyses represent steels marketed in this country:

Analyses of high-speed steels.a

C................

Mn. .............

Si...............

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

P................

Cr... ............

B-l.

0.66

1.27

.14

.04

.05

4.51

G.

0.72

.37

.18

.03

.02

4.50

K-2.

0.70

.18

.01

.02

4 or

D-l.

0.75

.28

.36

03

\ 4.10

-

W...............

V................

Co...............

Ni..... ..........

Mo.........:....

B-l.

17.48

.70

4.22

.17

0

G.

10 OA

2.50

K-2.

15.50

.88

4.72

.18

.67

D-l.

19 00

.75

a Hibbard, H. D., Manufacture and uses of alloy steels: U. S. Bur. Mines Bull. 100, 

p. 57, 1915.

1 Voigtlander & Lohmann Metall-Fabrikations Gescllschaft, m. b. Hi, German patent 

286184, Apr. 14, 1914. quoted in Chem. Abstracts, vol. 10, pp* 860-861, 1916. According to the claims of the patentees tungsten carbide has a hardness of 9.8 compared with 

the diamond as 10.
TUNGSTEN. 17

Of these steels D-l is said to have given excellent results and G was 

the winner in a competitive test.

Steels for light or finishing lathe work are made with only 3 or 4 

per cent of tungsten and no other metallic constituents. Some saw 

steels contain 2 per cent of tungsten.

A considerable quantity of tungsten is also used in magnet steels, 

iii proportions ranging from 0.8 to 8 per cent. One large automobile 

firm uses the smaller percentage in its magnet steels. A large electric 

firm uses 8 per cent, and this seems to be the percentage more generally used.

Tungsten is introduced into steel either as the powdered metal or as 

ferrotungsten, an alloy with iron containing 50 to 85 per cent of 

tungsten. One well-known automobile company, in making a lowtungsten steel, puts a small charge of tungsten in a heavy paper bag 

and throws it into the molten steel, into which it sinks with little 

opportunity for oxidation. Others are said to introduce the tungsten 

in steel tubes. Still others add ferrotungsten crushed to pieces less 

than an inch in diameter. The users of tungsten powder believe that 

it is dissolved by the steel more readily than ferrotungsten, but probably the principal reason for using tungsten powder instead of 

ferrotungsten is to prevent the introduction of carbon, for there is 

usually less carbon in tungsten than in ferrotungsten. The users of 

ferrotungsten believe that this objection is not serious and think that 

they avoid a considerable loss of tungsten through oxidation. The 

loss by either method, however, is said to be large, one steel maker 

estimating it at 20 per cent.

Probably the quantities of tungsten used in steel making in the 

form of tungsten and of ferrotungsten are nearly equal, tungsten 

constituting somewhat the larger part.

Its high melting point, the toughness and fineness of the wire into 

which it may be drawn, and its behavior when an electric current is 

passed through it make tungsten the best material now known for 

incandescent electric lamp filaments, so that for this use it is rapidly 

driving other material from the market. Incandescent lamps filled 

with nitrogen or argon and having tungsten filaments are taking the 

place of arc lamps for many purposes. Tungsten filament lamps are 

made in great numbers, but the filaments are so fine that an astonishingly small quantity of ore supplies the industry. Fink 1 states that 

" the total production of tungsten lamps, both vacuum and gas filled, 

in the United States in the year 1914 reached 100,000,000 (equivalent 

to 3 tons of tungsten concentrates)."

Patents have been issued for inclosed tungsten arc lamps, which 

the inventors claim will still further increase the efficiency of the

1 Fink, C. G., The mineral industry during 1914, p. 759, 1915. 

47154° Bull. 652 17 2
18 TUNGSTEN MINERALS AND DEPOSITS.

tungsten lamp. Some makers have used a filament containing a 

small percentage of thorium alloyed with tungsten. Dr. W. R. Whitney, chief of the research laboratory of the General Electric Co., in 

a paper read before tne Technology Congress at the Massachusetts 

Institute of Technology in 1911, said: .

A broader but perhaps less accurate impression of changes recently produced 

may be gained by considering the economy now possible on the basis of our 

present incandescent lamp purchases in this country and that which would have 

resulted if the lamps of only 10 years ago were used in their stead. On the assumption that the present rate of lamp consumption is equivalent to about 

eighty million 25-watt tungsten lamps per year, and on the basis of 1£ watts 

per candlepower as against 3.1 of the earlier lamps and of charging power at 10 

cents per kilowatt hour, we get as a result a saving of $240,000,000 per year, or 

two-thirds million per day. Naturally, this is a saving which is to be distributed 

among producers, consumers, and others but illustrates very well the possibilities.

Since that time the lamps filled with nitrogen and argon have been 

placed on the market and other improvements have been added which 

have made the incandescent electric lamp more efficient and have 

greatjy extended its applicability, so that the annual saving in cost 

for electricity and the pleasure and comfort due to good lighting 

have thus been very largely increased. The electric-light plants find 

added profit in the more general use of electricity that has followed 

the recognition of better service.

The development of a process for making ductile or malleable 

tungsten from the brittle, almost infusible, and unworkable powdered 

tungsten forms one of the romances of American industrial accomplishment. The process of manufacture is well described in the 

patent (No. 1028933),granted W. D. Coolidge, December 30, 1913.

Concerning the tungsten wire used in tungsten lamps, it is said 1 

that

the filament in a regular 10-watt lamp is about three-fourths mil (0.00075 inch) 

in diameter, which is probably the finest wire ever produced by straight drawing. At a recent industrial exposition a wire manufacturer exhibited some wire 

1$ mils (0.0015 inch) in diameter as a marvel of wire drawing.

The valves of some automobile engines are made of an iron-tungsten alloy and are said to stand the wear much better than iron or 

steel. Tungsten crucibles have also been made for use in vacuum 

furnaces or in furnaces filled with inert gases.

FORMS IN WHICH TUNGSTEN IS FOUND.

Tungsten has never been found as a native metal but always in 

chemical combination with other substances and in a small number of 

minerals, only nine being surely known. Comparatively few metals

1 Howell, J. W., The manufacture of drawn-wire tungsten lamps: General Electric Rev., 

vol. 14, p. 278, 1914.
TUNGSTEN MINERALS. 19

occur in a less number of natural combinations, and numerous elements are found in very many more. Thus, arsenic is a component 

of about 130 minerals, antimony of nearly as many, and iron probably of many more. Another peculiar fact is that tungsten is the 

principal constituent of nearly all known tungsten-bearing minerals. 

So far as the writer is aware, it has been found in traces or in minor 

percentages only in a few of the minerals that occur in pegmatites or 

in veins closely connected with pegmatites, and these are tin, titanium, 

tantalum, and columbium minerals. 'A possible exception is powellite 

(calcium molybdate,CaMo04 ),in which Melville 1 determined a small 

percentage of tungsten. Examinations of powellite obtained from 

several other sources indicate that the tungsten may have been present as scheelite (calcium tungstate, CaWOJ in a mechanical mixture 

with the powellite, like wheat and oats, rather than in a chemical 

compound like that which it might form with calcium and molybdenum. Most of the elements occur as traces in many minerals, and 

special search may show that tungsten occurs in many more. 2

The highest content of tungsten noted in the tantalum-columbium 

minerals in the analyses quoted in Dana's " System of mineralogy " 

is 5.51 per cent of W03 , in a mineral related to samarskite from 

debris at the foot of Devil's Head Mountain, Douglas County, Colo., 

analyzed by W. F. Hillebrand. Other analyses of the same mineral 

gave 2.08 and 2.25 per cent of W03 . Small quantities of WO3 , 

mostly less than 1 per cent, are also reported in the other columbiumtantalum minerals hatchettolite, microlite, fergusonite, sipylite, 

columbite, yttrotantalite, yttrocrasite, samarskite, and hielmite.

Many of-the analyses show a percentage of " W03 and Sn02 ," and 

it is perhaps just to regard a number of the determinations with suspicion. On the other hand it is possible that were a number of 

related minerals examined especially for tungsten it might be found 

in them.

TUNGSTEN MINERALS.

CHEMICAL AND PHYSICAL FEATURES.

The known minerals of tungsten are as follows:

The wolframites:

Ferberite, iron tungstate (FeWO*). Ferberite replacing scheelite 

(see PI. XVI, D, p. 32) has been called reinite. Ferberite may 

carry 20 per cent hiibnerite.

Hiibnerite, manganese tungstate (MnWO«). Hiibnerite has been described in some old works as megabasite. Hiibnerite may carry 20 

per cent ferberite.

1 Melville, W. H., Powellite, calcium molybdate, a new mineral species: Am. Jour. Sci., 

3d ser., vol. 41, pp. 138-141, 1891.

2 Since this bulletin was sent to the printer Melville's material has been examined 

microscopically by E. S. Larsen, and his determination seems to be confirmed, so that 

powellite may be regarded as a calcium tupgsto-molybdate.
20 TUNGSTEN MINERALS AND DEPOSITS.

The wolframites Continued.

Wolframite, iron-manganese tungstate [(Fe,Mn)WO*]. The iron

tungstate and manganese tungstate may bear any ratio to each

other from 20 per cent iron tungstate (ferberite) and 80 per cent

manganese tungstate (hiibnerite) to 80 per cent ferberite and 20

per cent hiibnerite.

Scheelite, calcium tungstate 1 (CaWOi). 

Stolzite, lead tungstate (PbWO*). 

Raspite, lead tungstate (PbWO*), differs from stolzite only in crystal

form. -

Cuprotungstite, hydrous copper tungstate (CuWO^HzO). 

Tungstite, hydrous tungsten trioxide (WO8.H2O), also known as tungsten

ocher. Meymacite, although described as carrying more water, is

probably the same .mineral. 

Ferritungstite, hydrous iron-tungsten oxide (Fe203.W03.6H2 0).

Tungsten minerals in common have a high specific gravity, show a 

general lack of good crystal form, and readily respond to tests for 

tungsten. According to their appearance they may be divided in a 

general way into two classes the more or less metallic-looking minerals and those which have a stony appearance. To the first class 

belong the iron and manganese minerals, ferberite, wolframite, and 

hiibnerite, though some forms of hiibnerite can in no sense be referred 

to as metallic-looking, and to the other belong the remaining minerals, scheelite, stolzite, cuprotungstite, tungstite, and ferritungstite.

All these minerals except possibly ferritungstite show good cleavages in one or more directions directions in which they split like 

wood. (See PI. IX.) In many specimens the cleavage is not very 

apparent because the individual crystals are so small that no large 

plane surface can be obtained by splitting the crystal in any direction. This is true of the wolframite from Lead, S. Dak., of much of 

the ferberite of the Boulder field in Colorado, and of the scheelite 

and cuprotungstite from many localities. Most specimens, however, 

if they are gradually turned in a strong light, will have a shiny or 

satiny appearance in one or more directions as the light is reflected 

from the cleavage faces.

It may be wondered why the irregularly shaped particles that 

make up the massive aggregates of tungsten minerals should be 

called crystals. The reason is that crystal character in a substance is 

a feature of its internal structure, of which the regular forms sometimes found (see Pis. I, II, III, VI, VII, VIII, and XVI) are 

merely the outward signs. Ideally every original individual particle 

of a mineral would take some such symmetric outward form, but the 

individual crystals in tungsten deposits grow against and into each 

other and against other minerals, which are, perhaps, forming at the 

same time, so that their growth is checked in all directions and outward perfection of form is impossible. Only when the crystals grow

1 Calcium oxide (CaO) is lime, so that scheelite is also referred to as "lime tungstate."
TUNGSTEN MINERALS. 21

in an open space or in some yielding, readily replaceable substance is 

outward crystal form developed.

The most perfect crystals of tungsten minerals found in this 

country are the ferberite crystals from the Boulder field in Colorado, 

where they occur in great beauty and much more plentifully than at 

any other known locality. (See Pis. I, II, and III.) Ferberite 

crystals are found also on Corral Creek, Blaine County, Idaho, but 

they are not so perfect as the specimens from Colorado. A few 

small but good crystals of wolframite have come from eastern San 

Bernardino County, Cal. (See PI. VII.) In the lower levels of 

some of the gold and silver mines at Tonopah, Nev., hiibnerite is 

found in slender reddish translucent crystals and in others of much 

darker color. A small number of imperfect reddish-brown crystals 

of hiibnerite have been found in the Began district, White Pine 

County, Nev. (See PI. VI, B.) A few good crystals of scheelite 

have come from the Snake Range, White Pine County, Nev., near 

Osceola; from the Deep Creek Range, Tooele County, Utah (see PI. 

XVI, A and B) ; from veins 4 miles north of Dragoon, Ariz.; and 

.from Leadville, Colo. (See PL XIV, A.) Crystals of scheelite, 

more or less replaced by wolframite, have been found at Trumbull, 

Conn. The rarity of well-formed- crystals of tungsten minerals is 

shown by the fact that such crystals have been found at only a few 

American localities, although many deposits are known.

THE WOLFRAMITES. 

COMPOSITION.

Wolframite was thje first tungsten mineral found, though for a 

long time its components were unknown. Careful studies showed 

not only that specimens of wolframite from different deposits differed greatly in chemical composition, but that specimens from- the 

same deposit and even material from different parts of the same 

crystal were of unlike composition. In general the wolframites first 

known were a black tungstate of iron and manganese whose composition was expressed by the formula (Fe,Mn)W04, It is rather 

peculiar that nearly all the wolframites found in Europe are of the 

darker iron-rich varieties,1 though manganese-rich species of brownish-red tints have been reported from Bayevka in the Urals of 

Russia,2 from Schlaggenwalde, Bohemia,3 and from Valcroze,

1 Hess, F. L., The mineral relations of ferberite: U. S. Geol. Survey Bull. 583, pp. 24-25, 

1914.

2 Kulibin, N. von, Manganhaltlger Wolfram aus der Grube Bajewsk am Ural: Russ. k. 

mineral. Gesell. Verb., 2d ser., vol. 3, p. 3, 1868.

3 Rammelsberg, C. F., Handbuch der Mineralchemie, p. 309, 1860. Fine red-brown 

needles, with fluorspar and apatite.
22 TUNGSTEN MINERALS AND DEPOSITS.

France.1 The nearly pure iron tungstate (FeWO4 ) was found in 

Sierra Almagrera, southern Spain, and was described by Liebe 2 in 

1863 under the name ferberite.

The nearly pure manganese tungstate (hubnerite, MnW04 ) was 

described by E. Biotte 3 from the Erie and Enterprise veins, Ellsworth, in the Mammoth district, Nye County, Nev., in 1865.

Efforts were made by a number of mineralogists and chemists to 

show that the wolframites were made up of relatively few chemical 

members, in which the proportion of molecules of manganese 

tungstate and iron tungstate were in ratios that could be expressed 

by comparatively small numbers, such as 1 part of MnW04 to 2 parts 

of FeW04 , 2 MnW04 to 3 FeW04 , and so on, but the writer 4 has 

shown that the series is composed of an infinite number of members 

and that its division into separate minerals must be made by fixing 

arbitrary limits. The following definitions were therefore proposed:

Ferberite should be considered an iron.tungstate (FeWOJ contaminated by not more than 20 per cent MnWO4 , a proportion 

equivalent to 4.69 per cent MnO, or 3.63 per cent Mn, in the pure 

tungsten mineral.

Hiibnerite should be considered a manganese tungstate (MnWO4 ) 

contaminated by not more than 20 per cent FeWO4 , a proportion 

equivalent to 4.74 per cent FeO, or 3.69 per cent Fe.

Wolframite should cover the ground between the limits above indicated. That is, wolframite should be considered a mixture of iron 

and manganese tungstates containing not less than 20 per cent nor 

more than 80 per cent of either.

Except the light-colored hiibnerites, most of these mixtures can 

not be distinguished by the eye or by simple tests, and in the absence 

of analyses it is therefore convenient to refer to the dark minerals of 

the series as wolframites.

FEEBERITE.

Physical features. Ferberite is a black mineral and to the unaided 

eye is opaque, but under the microscope very thin edges, probably 

not more than 0.0001 or 0.0002 inch thick, show a red color by light 

passed through them. Ferberite may be so coated with hydrous 

iron oxide or so intergrown with it that both the outside and 

the parts exposed by fracture or cleavage may be brown. Some 

specimens are iridescent owing to thin films of the oxide. Much of 

the ferberite from the Eogers tract, near Nederland, Boulder County, 

Colo., and from veins north of Rollinsville, on the north edge of

1 Lacroix, A., Mine"ralogie de la France et ses colonies, vol. 4, pt. 1, p. 293, 1910.

2 Llebe, K. L. T., Bin neuer Wolframit; ein Beitrag zur Mineral-Chemie: Neues Jahrb., 

1863, pp. 641-653.

3 Dana, J. D. and E. S., System of mineralogy, 6th ed., pp. 982-985, 1892.

4 Hess, F. L., The mineral relations of ferberite : U. S. Geol. Survey Bull. 583, pp. 

36-38, 1914.
U. S. GEOLOGICAL SURVEY BULLETIN 652 PLATE I

A. WEDGE-SHAPED FERBERITE CRYSTALS FROM "CROW PATENT," NEDERLAND,

COLO.

B. CRYSTALLIZED FERBERITE WITH ELONGATED RHOMBIC CRYSTAL 

FACES, FROM NUGGET MINE, GILPIN COUNTY, COLO.
U. S. GEOLOGICAL SURVEY BULLETIN 652 PLATE I

A. WEDGE-SHAPED FERBERITE CRYSTALS FROM HOOSIER MINE, NEDERLAND, COLO. 

 :- - - .- . *.,';- Enlarged 2 diameters.

B. CUBOID FERBERITE CRYSTALS FROM GEORGIA A. MINE, NEDERLAND, COLO. 

Enlarged 10 diameters.
TUNGSTEN MINERALS. 23

Gilpin County, Colo., are so much stained with iron that even 

freshly broken pieces are light brown. The color is due to hydrous 

iron oxide, probably limonite,1 which forms no part of the mineral. 

Plate VI, A, shows a polished section of a crystal of ferberite which 

contains cavities filled with limonite, disguising its color.

The specific gravity of ferberite is 7.499, or practically 7.5.

Ferberite shows a greater tendency to assume outward crystal 

form than other tungsten minerals, and some of its typical forms are 

shown in Plates I, II, and III. All the specimens shown are from 

the Boulder field, in Colorado, and are so typical that they can be at 

once told from minerals from any other locality, especially if the 

gangue is considered. Much the same tendency toward outward 

crystal form is shown by specimens of ferberite (?) found on Corral 

Creek, Blaine County, Idaho, but the crystal form of the specimens 

seen is not so perfect. Specimens from Elizabethtown, N. Mex., 

are-very much like those from Corral Creek and are said to carry 

2.16 per cent Mn. Ferberite found at Cave Creek, Ariz., shows 

a tendency toward coarser granular form and less regularity of outward shape.

The hardness 2 of ferberite is about 5, so that it is easily scratched 

by a pocketknife. Ferberite has one excellent cleavage, directly 

across the longer axis of the crystals as they are usually formed, and 

some specimens show another cleavage approximately at right angles, 

but it is not so perfect. Breaks other than with the cleavage show 

a rough " hackly " fracture.

If ferberite is scratched with a knife or is drawn across a streak 

plate made of unglazed china, the powder formed is dark brown to 

nearly black but never quite black. The powder formed by crushing the mineral is of the same color, for a streak is merely the powder 

formed by scratching or rubbing. The color of the streak may be 

disguised by iron oxide or other minerals. Thus the ferberite from 

the Rogers tract and some other places near Nederland, Colo., gives 

a light-brown streak on account of the limonite in and on it. At 

depths below which oxidation has penetrated limonite will no longer 

be present, and the darker iron mineral, hematite, from which it 

may have been formed, or possibly siderite (iron carbonate), will 

take its place, and probably neither will so much alter the appearance 

of the ferberite.

Other minerals may partly cover and disguise ferberite. Thus in 

many places the crystals are covered by chalcedony and clay, but on 

breaking the material across the mineral is exposed.

1 No analysis of the oxide has been made, but for convenience it will be called limonite, 

as it is at'any rate closely related to limonite.

2 The hardness of minerals is measured by what is known as the Mohs scale and is the 

resistance offered by a smooth, surface to abrasion. The scale is: 1, Talc; 2, gypsum; 

3, calcite; 4, fluorite; 5, apatite; 6, feldspar; 7, quartz; 8, topaz; 9, sapphire; 10, 

diamond.
24 TUNGSTEN MINERALS AND DEPOSITS.

Minerals of similar appearance. Specular hematite (an iron oxide, 

Fe2 03 ) occurs in veins in the Boulder field and near Yucca, Ariz., as 

aggregates of very small flakes, which can not be readily distinguished by the unpracticed eye from ferberite or wolframite. Many 

specular hematites are blue-black, but although the mineral may 

appear as black as ferberite it gives a red-brown streak, which immediately identifies it, and it will, of course, give no test for tungsten.

Magnetite (another iron oxide, Fe3 04 ) may form veins and masses 

much like ferberite. It breaks with a smoother, more lustrous surface 

than the wolframites, except on cleavage surfaces. There is also a 

hint of purple on many fresh magnetite surfaces. The streak is 

black, but the streak of even the purest f erberites is somewhat brownish. The minerals may readily be separated by a magnet, for magnetite is strongly attracted by a horseshoe magnet, even at a distance 

of half an inch or more. Some specimens of ferberite when finely 

powdered are feebly attracted by a horseshoe magnet, but not sufficiently to be mistaken for magnetite.

Ilmenite (an iron titanate, FeTiO3 ) may also be mistaken for ferberite, but it has no good cleavage and, like magnetite, it has, Vhen 

newly broken, a rather lustrous surface which shows a tint of deep 

purple. It is not attracted by a magnet. Most ilmenite found in 

pegmatites occurs in nearly black, solid platy crystals set at angles 

of 30 to 60° with each other. Specimens showing such structure have 

at different times been sent to the Survey from the northern part of 

the Colville Indian Reservation, Wash., by persons who thought they 

,were wolframite or some other valuable mineral. As a rule, the crystal 

surfaces of ilmenite have a steel-blue tint. The color, the luster of the 

broken face, and the lack of cleavage are usually sufficient to distinguish it from ferberite.

Summary of characteristics.---The notable characteristics of ferberite are its black color (in some specimens disguised by iron oxide); 

dark-brown or nearly black streak; excellent cleavage, showing 

lustrous black planes; hackly fracture; high specific gravity; and 

crystal form,1 the character of which is shown in Plates I-III.

Distribution. Ferberite has been found in the United States principally in the Boulder field, in Colorado. The Boulder field centers 

around Nederland, Boulder County, from which it extends about 

10 miles northeast, and scattered deposits have been reported from 

points through a distance 10 or 12 miles south. The belt is 4 or 5 

miles -wide. The Boulder district is by far the most important 

ferberite-producing district of the world. The locality from which 

the original mineral came the Sierra Almagrera, Spain is not

1 The crystal forms of ferberite have been technically and rather elaborately described 

by W. T. Schaller and the writer. See Colorado ferberite and the wolframite series: 

U. S. Geol. Survey Bull. 583, 1914.
U. S. GEOLOGICAL SURVEY 

A VERY FINE SPECIMEN OF FERBERITE WITH RHOMBIC CRYSTAL FACES, FROM 
U.S. GEOLOGICAL SURVEY

A. HUBNERITE FROM BIRDIE MINE, BUTTE, MONT. 

HUBNERITE FROM GLADSTONE, NEAR SILVERTON, COLO.
U.S. GEOLOGICAL SURVEY RULLFTIN 652 P> ATF. >

A. WOLFRAMITE WITH CINNABAR FROM JACK CLAIM, CLARK MOUNTAINS, NEAR NIPTON.CAL. 

B. BLACK HUBNERITE FROM WHITE OAKS, N. MEX.
TUNGSTEN MINERALS. , .25

known to have produced the mineral in commercial quantity; and 

although ferberite has been found in British Columbia, France, 

Italy, Indiaj New South Wales, Siberia, and Greenland, very little 

is known to have been put on the market jcrom these countries. It is 

possible, however, that more has been produced than is apparent, 

for published analyses of ore are few, and many ores may have been 

shipped under the better-known name of wolframite without real 

knowledge of their composition. In this country a little ferberite has 

been mined at Cave Creek, Ariz., and at a point 4 miles east of Hill 

City, S. Dak. The wolframite mined at Corral, Idaho, is probably 

ferberite^ and specimens of ferberite have been sent to the Geological 

Survey from Elizabethtown, Coif ax County, N. Mex. The ferberite 

mined in Colorado furnishes apparently between one-tenth and oneeighth of the world's tungsten production.

Importance as an ore mineral. Ferberite is probably the most desirable of the tungsten minerals as an ore mineral for the manufacture of f errotungsten, for there is little else in it than oxygen and the 

iron and tungsten desired in the product. For the manufacture of 

tungsten powder through roasting with soda and treatment with 

acids, it would seem to have no advantage over other tungsten minerals, and it is possibly somewhat more resistant to treatment.

A premium of 10 per cent over the price paid for other tungsten 

ores was advertised early in 1916 by certain buyers for ferberite ores 

in Colorado, but other buyers would not pay a premium for it.

HUBNERITE. *

Physical features. Hubnerite is the pure or nearly pure manganese tungstate, and it has been proposed to limit the term to 

minerals that contain not less than 80 per cent MnW04 , which, of 

course, can not then contain more than 20 per cent FeW04 .

Hiibnerite is typically reddish brown. (See PL IV, B.) Some 

specimens are almost garnet-colored, but a hubnerite from the Birdie 

mine, Butte, Mont., is in part light yellowish brown and in part 

caramel-brown, and a hubnerite from White Oaks, N. Mex., is to the 

eye opaque black. (See Pis. IV, A, and V, B.) Under the microscope, however, thin sections have light or dark yellowish-brown or 

dark-green colors by light passing through them, although parts of 

the same crystals may be opaque as seen in the section, which is 

0.03 to 0.05 millimeter (0.0012 to 0.002 inch) in thickness. The mineral from White Oaks contains only a fraction of 1 per cent of iron 

(0.55 per cent FeO), and the reason for its dark color is unknown. 

Lighter-colored hiibnerites may contain much more iron, like that 

from Dragoon, Ariz., an analysis of which shows 2.66 per cent 

FeO.1

1 Guild, F. N., The mineralogy of Arizona, p. 92, 1910.
26 TUNGSTEN MINERALS AND DEPOSITS.

Hiibnerite shows a constant tendency to form thin, flat, radial, 

irregular crystals, and very few, if any, good crystals have been 

found. However, in all these tungsten minerals, as in many other 

minerals, should good crystals be formed they are likely to be 

embedded in a later growth of quartz and thus lost. Some crystals 

from Tungstonia, in the Red Hills, Regan district, White Pine 

County, Nev., courteously supplied by Mr. C. G. Simms, are shown 

in Plate VI, B. In some of the lower levels of the silver-gold mines 

at Tonopah, Nev., there are numerous thin platy crystals of red 

hiibnerite which in form remind one of a small fragment split from 

a wheat straw. Some of them are nearly black and may be wolframite, but as black crystals are found in the hiibnerite from White Oaks, 

N. Mex., and as some of the crystals from Tonop'ah are red, the material is possibly all hiibnerite. Hiibnerite is not known to occur in 

masses so fine grained as ferberite.

The specific gravity of hiibnerite, about 7.2 to 7.3, is somewhat 

Jess than that of ferberite. Its hardness is nearly the same as that 

of ferberite, about 5 that is, it is easily scratched by the blade of a 

pocketknife.

The streak of the reddish varieties is light brownish red, the 

streak of the material from Butte is light greenish yellow, and that 

from White Oaks, N. Mex., is somewhat greenish yellow. The varieties that contain iron and that thus approach wolframite in com. 

position have darker streaks.

Hiibnerite may be difficult to identify on account of coatings of 

manganese dioxide, which color it black, or of limonite, the brown 

iron oxide.

Minerals of similar appearance. Sphalerite (zinc blende) and 

garnet have been mistaken for hiibnerite, and some specimens have 

nearly the same reddish color. Sphalerite has excellent cleavages 

in several directions; hiibnerite only one. Crystals of sphalerite tend 

toward equidimensional forms, hiibnerite toward elongated radial 

forms. The specific gravity of sphalerite is only about 4, a little more 

than half that of hiibnerite.

Garnet has no cleavage, broken faces of it have a greasy luster, 

and its crystals are chunky. Rutile may have a color very near 

that of some hiibnerite, but it has no cleavage, or a very poor one, 

and can not be scratched with a knife.

Distribution. Hiibnerite is mined in this country at Tungsten, in 

the Snake Range, 12 miles south of Osceola, Nev.; at Tungstonia, 35 

miles north of Osceola, Nev.; near Columbus, Mina, Spanish Springs, 

and Round Mountain, Nev.; on Patterson Creek, in the Blue Wing 

district, Idaho; Silverton, Colo.; White Oaks, N. Mex.; and Dragoon, 

Ariz. It is known5 also at some other places in the United States. 

The tungsten mineral mined at Arivaca, Ariz., greatly resembles
U. S. GEOLOGICAL SURVEY BULLETIN 652 PLATE VI

A. CUT AND POLISHED CRYSTAL OF BROWN FERBERITE FROM 

WINNEBAGO CLAIM, NEAR ROLLINSVILLE, COLO.

Enlarged 78 diameters. Shows spongy structure of the ferberite, the cavities of 

which (dark portions of the photograph), though invisible to the unaided eye, 

are filled with hydrous iron oxide, which colors the mineral.

'il

J I

_??. HUBNERITE CRYSTALS FROM REGAN MINING DISTRICT, 35 MILES NORTH OF OSCEOLA, NEV. 

Natural size. In the figure at the right in the upper row the crystals at the left are hubnerite, the remainder quartz.
U. S. GEOLOGICAL SURVEY BULLETIN 652 PLATE VII

B

WOLFRAMITE CRYSTALS FROM JACK CLAIM, CLARK MOUNTAINS, NEAR NIPTON, CAL.

A. Wolframite crystal (in center) with rounded octahedra of scheelite perched upon it. Enlarged 2 diameters,

Compare with individual ferberite crystals shown in Plate I, 7?. 

B. Wolframite crystals, whose faces tend toward a square form, with rounded octahedra of scheelite. Enlarged

1 0 diameters. Compare with crystals shown in Plate 11, />'.
TUNGSTEN MINERALS. 27

hubnerite, but A. L. Pellegrin i claims it contains enough iron to be 

considered a wolframite. It has not been analyzed by the Survey. 

At one time a few tons of the yellowish-brown hubnerite already 

referred to was taken from the Birdie mine, near Butte, Mont.

Abroad, hubnerite is mined in Peru and is shipped to this country. 

It is also mined in New South Wales and Queensland, and a little 

has been found in Canada, Germany, Siberia, and other countries.

Importance as an ore mineral. Hubnerite is produced in small 

quantity and is therefore the least important of the four principal 

minerals, which, named in descending order of the quantity produced, are wolframite, ferberite, scheelite, and hubnerite.

Those who smelt ferrotungsten do not generally buy hubnerite so 

readily as ferberite or wolframite, but this discrimination seems to 

be due in part rather to a disinclination to change fluxes than to 

more real disadvantages. Some consumers make no distinction between hubnerite and the other minerals, and those who are seeking a 

market for ores should keep this fact in mind. If one buyer does not 

accept the mineral at the market price for other tungsten minerals 

another buyer should be sought.

WOLFRAMITE.

Physical features. Wolframite is in general a black mineral, 

which rarely shows good outward crystal form. Characteristic 

crystals are shown in Plate VIII. These crystals are from Zinnwald, Bohemia. Very much smaller but more perfect crystals from 

the Clark Mountains, in eastern San Bernardino County, Cal., are 

shown in Plate VII. Large imperfectly terminated crystals embedded in quartz and chalcopyrite and other sulphides are shown 

in Plate IX. This specimen, which is from Cornwall, England, 

shows excellently the cleavage that is characteristic of all the wolframites. Most wolframite occurs in irregular aggregates of individuals showing no outward crystal form, and these may range in 

size from microscopic dimensions to 2 inches or more across. Thus 

in the wolframite from L'ead, S. Dak. (PI. X, Z?), the individual 

crystals are indistinguishable.

The specific gravity of wolframite ranges between that of hubnerite 

and that of ferberite, from 7.2 to 7.5.

The hardness of wolframite is also nearly the same as that of the 

two end members of the series, about 5.

The streak ranges from reddish brown in the minerals which are 

most like hubnerite in composition to dark brown in those that are 

near ferberite. The cleavage is as prominent in one plane as that of 

ferberite and hiibnerite. (See PI. IX.)

1 Personal communication.
28 TUNGSTEN MINERALS AND DEPOSITS.

As already stated, the composition of the wolframites grades by 

infinitesimal degrees from ferberite to hiibnerite, and any division 

between the members must be arbitrary. Between 80 per cent of 

one and 20 per cent of the other there may be all possible combinations of the two molecules.

Wolframite may also be used as a family name for all the dark 

tungsten minerals whose composition is not definitely known except 

that they contain iron, manganese, and tungsten.

The same coatings of iron oxide and manganese oxide which may 

disguise ferberite and hiibnerite may make it difficult to distinguish 

wolframite.

Minerals of similar appearance. The principal minerals that may 

be mistaken for wolframite are specular hematite, manganese dioxide 

(psilomelane), magnetite, columbite, hornblende, and dark pyroxene.

Specular hematite gives a streak which is too red for wolframite, 

and when the flakes are large enough to be mistaken for the cleavage 

planes of wolframite, they are. almost invariably curved and bluish 

black. Wolframite cleavage planes are not known to be curved 

and are never bluish.

Manganese dioxide is iron-black to steel-gray, colors which are unlike the black of wolframite, and is invariably comparatively fine 

grained. The specific gravity (3.7 to 4.7) is also too low for wolframite.

Magnetite is readily distinguished by its lustrous fractured faces, 

its black streak, and especially by its attraction for a magnet. The 

prospector may well have the blades of his pocket knife magnetized 

for such determinations.

Columbite shows no cleavage, a test on which great dependence 

may be placed.

Hornblende and pyroxene are in some places found in dark stout 

crystals, an inch or more long, embedded in light-colored groundmasses, and may prove very puzzling. Both minerals are much too 

low in specific gravity (3 to 3.6) to be mistaken for wolframite, 

and they give light-colored stony powders .or streaks.

Distribution. Wolframite is mined in this country near Yucca, 

Columbia (Tip Top), Nogales, Hillside (Eureka district), and Benson (Whetstone Mountains), Ariz., though some of the Arizona mineral may be ferberite; in the Clark Mountains, Cal.; Penasco, 

N. Mex.; Hill City, S. Dak.; near Cathedral Peak, Okanogan County, 

and Cedar Canyon, Stevens County, Wash. Abroad it is mined in 

Bolivia, Argentina, Australia (Northern Territory, Queensland, New 

South Wales, Victoria), Tasmania, Burma, Federated Malay States, 

Siam,'Japan, Chosen (Korea), Northern Shan States, England 

(Cornwall, Devonshire, and Cumberland), France, Germany, Portugal, Spain, and Austria (Bohemia).
U. S. GEOLOGICAL SURVEY

A

WOLFRAMITE CRYSTALS FROM ZINNWALD, BOHEMIA. 

Natural size. Compare with ferbente crystals shown in Plate II, A.
LARGE, IMPERFECT CRYSTALS OF WOLFRAMITE EMBEDDED IN QUARTZ AND CHALCOPYRITE

FROM CORNWALL, ENGLAND.

Natural size.
TUNGSTEN MINERALS. 29

The United States is unique in that it mines more of both ferberite 

and scheelite than of wolframite, and it seems probable that in 1916 

it may also have produced more hiibnerite than wolframite, but in 

most countries more wolframite is mined than all other tungsten 

minerals together.

Importance as an ore mineral. Wolframite is apparently the favorite tungsten mineral, especially among foreign users, as has been 

explained, probably partly from habit and partly because it requires 

less fluxing than hiibnerite or scheelite. But undoubtedly the preference is in part due to mere habit, because it was the first tungsten 

mineral used, and it seems likely that hiibnerites from other countries 

are sold without question under the name wolframite. The demand 

for it in this country is probably second to that for ferberite.

SCHEELITE.

Physical features. In appearance scheelite is totally different from 

minerals of the wolframite series. Most of them give at once the 

impression that they are metallic minerals, but scheelite is as stony 

looking as quartz, feldspar, or marble. It occurs chiefly in granular 

irregular masses, like the feldspars or like calcite in coarse marble. 

Crystals are found here and there, but they are scarce. The large 

scheelite deposits at Atolia, Cal., are not known to have yielded even 

a single imperfect crystal. As has been noted, a few crystals have 

been found at some places in the United States. (See PI. XVI.) 

Scheelite has a characteristic,- very noticeable greasy luster on freshly 

broken faces. ,

Scheelite is, as a rule, nearly opaque as seen in masses, and even 

in thin sections prepared for microscopic work (0.03 to 0.05 millimeter, 0.0012 to 0.002 inch thick) it is generally cloudy. All American crystals seen by the writer have been deep cloudy to translucent, 

but a transparent crystal weighing about 2 pounds has been reported 

from the east side of the Snake Kange, Nev. Some crystals from 

other countries, especially from Japan, are beautifully transparent.

In color scheelite is nearly pure white (like the mineral from Atolia, 

Cal., and part of that from the Snake ;Range, Nev., and the deposit 

north of Lucin, Utah), creamy, straw-yellow, bright yellow, reddish 

caramel-colored, gray, or greenish gray. Generally the scheelite 

which appears yellow receives its color from tungstite formed along 

cracks. A small specimen from the Clark Mountains, San Bernardino County, Cal., is, however, a clear brilliant yellow. Plates XI 

to. XV show a number of specimens of scheelite as nearly in their 

natural colors as it has been practicable to reproduce them. The 

nearly white scheelite from Atolia is shown in Plate X, A.

The specific gravity of scheelite is about 6, varying about one-tenth 

of a unit either way. It is a little less than that of the minerals of
30 TUNGSTEN MINERALS AND DEPOSITS.

the wolframite group but more than twice that of quartz (2.65), 

calcite (2.71), or granite (about 2.80). Its hardness is 4.5 to 5, so 

that it is easily scratched by a knife. Scheelite cleaves fairly well 

in four directions and less well in four other directions, so that one 

or more of these cleavages may be seen in practically all broken specimens, if they are turned in the light until it is reflected by the cleavage planes.

When pure, scheelite contains 80.6 per cent tungsten trioxide 

(W03 ) and 19.4 per cent lime (CaO).

Scheelite is in some places found with the wolframite minerals. 

Plate XIII, A, shows pa'rt of a vein which had bristling crystals of 

wolframite along its walls, over which some quartz was deposited, 

and the middle of the vein was then filled with gray scheelite. 

Plate XI, Z?, shows hiibnerite from Dragoon, Ariz., which was broken 

after crystallization and in the cracks of which scheelite was deposited. Scheelite is commonly found in small quantity in veins of 

ferberite, wolframite, and hiibnerite, but these minerals are rare in 

scheelite veins, though they are not unknown. The great bulk of 

scheelite comes from veins that carry no other tungsten mineral.

Like the other tungsten minerals, scheelite may be so much discolored by iron oxide that its identification is difficult, especially if 

it is broken or crushed so that fresh surfaces can not readily be 

obtained.

Minerals of similar appearance. Owing to its variation in color 

and size of grain scheelite may not be recognized by 'casual examination because of its resemblance to epidote, garnet, barite, apatite, and 

calcite, minerals that have -frequently been mistaken for scheelite.

Epidote and garnet are much harder than scheelite; epidote can 

barely be scratched with a knife and garnet not at all. Garnet has 

no cleavage. Both have a greasy luster, and their specific gravities, 

3 to 3.6 and 3.5 to 3.6, are much lower than that of scheelite. All 

three minerals are of many tints, but the color of scheelite as a rule1 

is unlike that of the other minerals.

Barite has cleavages in three directions, so perfect that if it is 

coarsely crystallized it may be cleft into blocks that show rhombic 

faces and that may almost immediately be distinguished from scheelite. Barite is not so lustrous as scheelite, and it has a lower specific 

gravity (4.3 to 4.6). It is much softer than scheelite (its hardness 

is 3), so that one means of identification is to scrape a smooth surface 

of it with the back of a knife blade. A powder is in this way much 

more easily made from barite than from scheelite. Barite commonly 

crystallizes in thin plates, a habit totally unlike that of scheelite. 

Some barite, however, is fine grained and shows no cleavage, and its 

surface is so rough that the scraping test is inconclusive. Under
U, S. GEOLOGICAL SURVEY

\-'r

^. SCHEELITE FROM PAPOOSE MINE, ATOLIA, CAL.

Natural size. The straight lines show the edges of quartz plates and masses once deposited along cleavage 

planes in calcite, which has since been replaced by the scheelite.

11. WOLFRAMITE FROM WASP NO. 2 MINE, 2 MILES SOUTH OF LEAD, S. DAK.

Natural size. The wolframite has replaced Cambrian dolomite, and the white lines are the edges of shells that 

. . were not replaced.
U, S. GEOLOGICAL SURVEY

A. SCHEELITE (BUFF) WITH QUARTZ (WHITE), PYRITE (GREENISH), AND GALENA (NEARLY BLACK)

FROM GOLDEN CHEST MINE, MURRAY, IDAHO. 

B SCHEELITE (CREAMY) WITH HUBNERITE AND QUARTZ FROM VEIN 4 MILES NORTH OF DRAGOON, ARIZ.
U.S. GEOLOGICAL SURVEY

A. SCHEEL1TE FROM CLIFTON MINING DISTRICT, DEEP CREEK MOUNTAI NS, TOOELE COUNTY, UTAH. 

B. SCHEELITE AND GRAY QUARTZ FROM Kl MBERLY-MONTANA MINE, JARDINE, MONT.
U. S. GEOLOGICAL SURVEY

A. SCHEELITE (GRAY) WHICH HAS FORMED OVER A COMB OF WOLFRAMITE (BLACK) AND QUARTZ.

From Jack claim, Clark Mountains, near Nipton, Cal.

B. SCHEELITE (LIGHT YELLOWISH AND GREENISH) WITH QUARTZ AND CHLORITE (NEARLY BLACK), 

From a contact-metamorphic deposit on Corning Power claim, 15 miles north of Lucin, Utah.
U. S. GEOLOGICAL SURVEY

//. SCHEELITE (IN CENTER) WITH PYRITE AND QUARTZ FROM BREECE HILL, LEADVILLE, COLO. 

S. SCHEELITE AND QUARTZ FROM SCHEELITE. 6 MILES SOUTH OF OSCEOLA, WHITE PINE

COUNTY. NEV.
U. S. GEOLOGICAL SURVEY

A. STOL2ITE FROM BROKEN HILL, NEW SOUTH WALES.

Courtesy of C. A. Sussmilch.

8. TUNGS1ITE FROM KOOTENAY BELLE MINE, BRITISH COLUMBIA.

Courtesy of Dr. T. L. Walker, Geological Survey of Canada.

C. SCHEELITE STAINED WITH TUNGSTITE.

D. SCHEELITE STAINED BY IRON.

C and D from Zacatecas, Mexico. Exact locality unknown. 

E. SCHEELITE WITH QUARTZ IN CHLORITE SCHIST FROM MOOSE RIVER, NOVA SCOTIA.

Later information shows that Cand D are from Yaqui River, Sonora, Mexico.
TUNGSTEN MINEEALS. 31

such circumstances the test for tungsten (see p. 66) should be made 

and is conclusive.

Apatite in white masses an inch or more thick is found with 

scheelite in the Deep Creek Mountains, Utah, and greatly resembles 

white scheelite. Its specific gravity (about 3.2) is much less than 

that of scheelite, but its hardness and luster are about the same. A 

test for tungsten may be necessary to differentiate the two minerals.

Calcite has excellent cleavages in three directions and less perfect 

cleavages (called partings by crystallographers) in three other directions, so that, like barite, it may be cleft into regular four-sided 

blocks having rhombic faces, and the cleavage may be seen even in 

small fragments. Its specific gravity (2.7) is less than half that of 

scheelite. Its hardness (3) is also much less. An easy way of distinguishing calcite is by its effervescence with acids. If a little acid 

is put on calcite, especially powdered calcite, carbon dioxide gas is 

formed and bubbles through the liquid.

Summary of characteristics. The most notable characteristics of 

scheelite are its high specific gravity, greasy luster, brilliant cleavage 

planes, and the ease with which! it can be scratched with a knife. 

These, of course, are the- characteristics of fresh, clean surfaces. 

Most of them may be hidden by dirt and abrasion.

Distribution. Scheelite has been found in commercially valuable 

quantities at the places indicated below: In Alaska, 15 miles north of 

Fairbanks and in placers near Nome. In Arizona, at Oracle, Final 

County, 4 miles north of Dragoon, and near Duquesne. In California, at Atolia (PL X-, A) and Randsburg, San Bernardino 

County; with wolframite in the Clark Mountains, San Bernardino 

County, 18 miles south .of the Inyo County line and 9 to 10 miles from 

the Nevada boundary (PI. XIII, A) , at Amalie, in Jawbone Canyon, 

and near Weldon, Kern County; Grass Valley, Nevada County; and 

at several places near Bishop, Inyo County. In Connecticut, at 

Trumbull. In Idaho, at Murray, Shoshone County (PL XI, A). 

In Nevada, at Sacramento Pass, 10 miles north of Osceola; at Camp 

Bonita, on the opposite side of the Snake Range and southeast of 

Osceola; at Scheelite, 6 miles south (PL XIV, B) ; and in the 

Minerva, district, 25 miles south of Osceola, White Pine County. 

In Utah, in the Deep Creek Mountains, Tooele County (Pis. XII, A, 

and XVI, A and 5), and in the Grouse Creek Mountains, Box 

Elder County, 15 miles north of Lucin (PL XIII, B).

Scheelite has been mined on Moose River, Nova Scotia (PL XV, 

E] ; at McRaes Flat, New Zealand; at Hillgrove and other places in 

New South Wales; at Parada and other places in Queensland; at 

places in the Federated Malay States; and in Japan.
32 TUNGSTEN MINERALS,AND DEPOSITS.

Importance as an ore mineral. The deposits at Atolia are the 

largest and most productive scheelite deposits known, and the output has in some years equaled or exceeded that of ferberite from 

Boulder County, Colo.

Scheelite, under normal ore prices, has sold at about 50 cents a 

unit below ferberite and wolframite. This difference in price is, in 

part at least, apparently due to rule-of-thumb methods of smelting, 

for one tungsten smelter, who had on hand a stock of ferberite when 

it was selling for $7.50 a unit, is known to have sold it and bought 

scheelite at $7 a unit. The methods of fluxing must, of course, be 

changed when the smelter has been using wolframite alone, and this 

change makes more or less trouble. One manufacturer uses a mixture 

of scheelite and ferberite or wolframite in his charge. Others prefer 

scheelite alone, and it seems probable that any discrimination against 

it will disappear.

CUPBOTUNGSTITE.

Cuprotungstite is a hydrous copper tungstate of a bright yellowishgreen color. It has been found in only small quantities and is of 

little importance commercially. DanaJ gives its composition as 

CuWO4 and (Cu, Ca)W04 , but an analysis of material from Cave 

Creek,, Ariz., by W. T. Schaller, of the United States Geological 

Survey, shows that it contains water and that the formula should 

be CuW04.2H2 0. Three of the four analyses quoted by Dana show 

water, and in the fourth analysis, which totals only 97.85 per cent, 

apparently no determination of water was made. Dana seems to 

apply the name cuprotungstite to the copper tungstate and cuproscheelite to the supposed tungstate of copper and calcium, such a mineral from Lower California having been described by .Whitney. 

Whitney's original specimen is in the United States National Museum, 

and' examination shows it to be a mixture of cuprotungstite and 

scheelite. A specimen from New South Wales labeled "cuproscheelite and scheelite " is a similar mixture.

Cuprotungstite appears to be formed by the alteration of scheelite, 

the changes taking place along its outer surface and along cracks 

and extending inward. It naturally happens that the outer part 

may be more completely altered to cuprotungstite than the inner 

parts (PI. XVII,5), so that some reports are like that made by 

Domeyko,' a noted geologist of Chile, who states that cuprotungstite 

from a vein rich in copper near Santiago enveloped kernels of cuproscheelite and clear yellow scheelite,2 though he does not use these 

names. This cuproscheelite is therefore,. like Whitney's, merely a 

mixture of cuprotungstite and scheelite.

1 System of mineralogy, 6th ed., p. 988, 1892.

2 Domeyko, Ignacio, Note sur quelques mine'raux du Chili: Annales cles mines, 6th ser., 

vol. 16, pp. 537-538, 1869.
U. S, GEOLOGICAL SURVEY BULLETIN 652 PLATE XVI

D

CRYSTALLIZED SCHEELITE. 

All natural size.

A, B, Light-gray, slightiy translucent specimens from Clifton mining district, Deep Creek Mountains, Tooele 

Count Utah.

, County,ny a.

C. Specimen of reddish-caramel color, translucent, from Tungsten, 12 miles south of Osceola, Nev 

D, Scheelite partly replaced by ferberite (reinite) and tungstite, from Kurasawa mine, Koshu, Japan. Courtesy 

of S. Katsuno.
U. S. GEOLOGICAL SURVEY

A. CUPROTUNGSTITE (GREEN) AND FERBERiTE (BLACK) FROM CAVZ CREEK, AR!Z.

B. SCHEELITE (WHITE) BEING REPLACED BY CUPROTUNGSTITE (GREEN). 

Photomicrograph of specimen from Peelwood, New South Wales. Magnification 20 diameters.
TUNGSTEN MINERALS. 33

In hardness and cleavage cuprotungsite is very similar to scheelite. 

Cuprotungstite has never been found in any considerable quantity, 

and has thus not entered into commerce, but certain buyers have refused to buy ferberite from Cave Creek, Ariz., because it contained 

Cuprotungstite. Others, however, will purchase it.

The only known considerable deposit of Cuprotungstite in this 

country is that just mentioned, at Cave Creek, Ariz., where it occurs 

with ferberite and copper minerals, from the mutual decomposition 

of which it may have been formed. (See PI. XVII, A.) Specimens 

of wolframite from the.Copper Mountain (Picuris) district, near 

Rinconada, N. Mex., contain small quantities of a green mineral 

which may be Cuprotungstite. It is found in Lower California; Lannico and Santiago, Chile; Southwest Africa; and Peelwood, New 

South Wales. (See PI. XVII, B.)

TUNGSTITE.

Tungstite (hydrous tungsten oxide, W03 .H2 0), or tungsten ocher, 

was originally described as free from water, and was later named 

meymacite by Carnot,1 a French chemist, who thought he had discovered a new mineral because it contained water, but Walker 1 has 

shown that water is.a normal constituent of tungstite. Tungstite is 

a bright-yellow mineral which is formed by the decomposition of 

scheelite and the wolframites. It usually occurs as a yellow coating 

on those minerals or fills cracks in them. It is generally powdery, 

but it also forms visible crystals. Some scheelite is made yellow, 

from tungstite that has formed along small cracks which penetrate 

the entire mass. (See PL XV, 0.) Some specimens are so perfectly 

replaced that the cleavage of the original mineral is preserved. A 

specimen of tungstite from the Kootenay Belle mine, 10 miles southeast of Salmo, British Columbia, furnished through the courtesy of 

Dr. T. L. Walker, of Montreal, Canada, is shown in Plate XV, B. 

Dr. Walker 3 reports that

Mr. John Bell, of Salmo, who operated the Kootenay Belle when the best tungsten ores were obtained, informs me that on one occasion fully half a car of 

high-grade tungstite ore was shipped to the smelter. In this ore free gold 

occurs in the tungstite as well as in the quartz. Only gold values were obtained, the tungsten apparently going to waste, as its value was not known at 

the time.

Under prices prevailing late in 1915 and early in 1916 such ore 

would probably have been much more valuable for its tungsten

1 Carnot, A., Sur quelques mlne'raux de tungst&ne de Meymac (Correze) : Compt. Rend., 

vol. 79, p. 639, 1874.

3 Walker, T. L., A review of the minerals tungstite and meymacite: Am. Jour. Sci., 4th 

ser., vol. 25, pp. 305-308, 1908.

3 Walker, T. L., Report on the tungsten ores of Canada: Canada Dept. Mines, Mines 

Branch, p. 37, 1909.

47154° Bull. 652 17 3
34 TUNGSTEN MINERALS AND DEPOSITS.

content than for its content of gold and silver, but tungstite is not 

known to have occurred at other places in quantity comparable with 

that found at this mine.

Tungstite has been found at many places in this country but in 

insignificant quantities. It may, however, indicate to the prospector 

the occurrence of other tungsten minerals below the surface, as in 

some places it lines parts of cavities from which such minerals 

have been weathered. 1

FERRITUNGSTITE.

Ferritungstite, hydrous ferric tungstate (Fe2 03 .W03 .6H2 0), is 

a light-yellow mineral much paler than tungstite. It is friable or 

powdery and looks very much like iron-stained clay. Under the 

microscope it is seen to be made up of small hexagonal plates. It was 

found on specimens of wolframite collected by Howland Bancroft, 

of the United States Geological Survey, ^in the Deer Trail mining 

district, Stevens County, Wash., and has been described by W. T. 

Schaller.2

Ferritungstite has been found only as a product of the decay of 

wolframite, and, like tungstite, may be left in spaces from which 

wolframite has been weathered, and it may thus show the prospector 

that other tungsten minerals lie below the weathered outcrop.

Although it has been reported only from the Deer Trail (Cedar 

Canyon) district, Stevens County, Wash., it has probably in many 

places been taken for tungstite or an iron mineral. On the other 

hand, a claylike mineral stained with iron and covering hiibnerite, 

from Tungstonia, in the Regan mining district, 35 miles north of 

Osceola, Ney., could not be distinguished from ferritungstite without 

careful testing.

STOLZITE.

Stolzite, lead tungstate (PbW04 ), is a rare mineral, which is 

generally found in forms very much like those of scheelite but has 

never been discovered in large quantity. It is as diverse in its 

colorings as scheelite and is described by Dana 3 as green, yellowish 

gray, brown, and red. It is faintly translucent. The streak and 

powder are uncolored.

It contains 51 per cent tungsten trioxide, WO3 (40.5 per cent 

tungsten) and 49 per cent lead oxide, PbO (45.5 per cent lead). 

Stolzite and raspite are the only known tungsten minerals in which 

another metal exceeds the tungsten in quantity.

A little stolzite has been found in specimens from the scheelite 

deposits in the Grouse Creek Mountains, 15 miles north of Lucin,

1 * See appendix (p. 76).

2 Schaller, W. T., Mineralogical notes, series 2 : U. S. Geol. Survey Bull. 509, pp. 83-84, 

1912.

3 System of mineralogy, 6th ed., p. 989, 1892.
TUNGSTEN DEPOSITS. 3,5

Utah, and it is reported from Silvermine, Mo., and from Loudville 

and Southampton, Mass. It is apparently a secondary mineral and 

is reported to occur in the wulfenite and vanadinite ores of the 

Southwest, from which it must be removed if the ores are to be used 

for their molybdenum or vanadium content.

. It is reported from Zinnwald, Bohemia; Province of Coquimbo, 

Chile; Bena e Padru, Ozieri, Sardinia; Marianna de Itacolumy, 

Minas Geraes, Brazil; and Broken Hill, New South Wales. The 

specimen figured in Plate XV, J., is from Broken Hill.

BASPITE.

Easpite is a lead tungstate which has the same composition as stolzite" but which crystallizes in forms different from those of stolzite. 

It has been found only as a mineral curiosity in New South Wales 

and Brazil. It is unknown in the United States.

TUNGSTEN DEPOSITS. 

ASSOCIATED BOOKS.

Tungsten deposits seem to be invariably in or associated with 

granitoid rocks that is, with rocks resembling granite in texture 

though they may be with their porphyritic facies, and, so far as is 

known, only with rocks that contain considerable quantities of free 

quartz, and usually if not always with the lighter-colored rocks.

Generally the deposits are obviously connected with the granitoid 

rocks either in them or in rocks that are plainly in contact with 

them. Near the wolframite deposits at Lead, S. Dak., no granite 

is found, but probably no one who has studied them doubts that 

granite lies not far below the deposits. The wolframite deposit in 

the Hachita district, near Gage, N. Mex., is in limestone, but here, 

too, granitoid intrusions will probably be found at no great distance 

from the deposit, either vertically or horizontally, for, according to 

Lindgren,1 the limestones are cut by numerous dikes and sheets of 

quartz monzonite porphyry.

Tungsten deposits, like tin deposits, appear to be connected with 

the upper and outer part of intrusive masses of granitoid rocks, so 

that if a considerable thickness of the rocks has been eroded the 

tungsten deposits may have been removed, and thus lost to man, 

and this may account for the absence of tungsten deposits in the 

neighborhood of some great granite masses. On the other hand, the 

rock core of the earth apparently varies considerably in composition 

from place to place, so that the different kinds of ore deposits are 

very unequally distributed.

1 Lindgren, Waldemar, Graton, L. C., and Gordon, C. H., The ore deposits of New 

Mexico : U. S. Geol. Survey Prof. Paper 68, p. 336, 1910.
36 .TUNGSTEN MINERALS AND DEPOSITS.

DISTRIBUTION IN THE UNITED STATES.

The tungsten deposits of the United States, as would be expected 

from the statements just made, occur only in States where there are 

areas of quartzose granitoid rocks, but, as has been intimated, not all 

areas of granitoid rocks contain tungsten deposits.

Most of the tungsten deposits of the country are in States that lie 

in and west of the Eocky Mountains-r-South Dakota, Montana, Colorado, New Mexico, Idaho, Utah, Arizona, Nevada, California, Oregon, and Washington all of which contain at least small deposits. 

Wyoming is the only State in this whole great western area in 

which no tungsten is known to have been found. In the southeast 

quarter of Missouri, at Silvermine, Madison County, there is a 

small area of granitoid rocks containing wolframite, and it has 

also been reported, though without confirmation, from one or two 

other points in this area. In the granites and related rocks exposed 

from Maine southward to Georgia, however, very little tungsten has 

been found. Scheelite has been mined on a small scale at Trumbull, 

Conn., but at no other point in this whole eastern area have tungsten 

minerals been exploited, although sporadic occurrences have been 

noted at several places and pieces of wolframite can be picked out of 

the dumps of the old Irish Creek tin mine, in Eockbridge County, 

Va., 5 miles east of Vesuvius.

There are areas, some very large, of granitoid rocks in Alaska, 

Arkansas, Michigan, Wisconsin, and Minnesota from which no tungsten minerals have been reported. In Texas there are small areas of 

granitoid rocks in which a few tungsten minerals have been found, 

and in Alaska further discoveries are to be expected. 

, The wolframite minerals, particularly hiibnerite, seem to occur 

preferentially with silver deposits and scheelite with gold deposits. 

Thus the Eocky Mountain and Great Basin States, which are preeminently silver-producing areas, carry the largest deposits of ferberite, wolframite, and hiibnerite, and in the Sierra Nevada, which 

is a gold-producing area, the greatest known scheelite deposits are 

. found at Atolia, at the south end of the range. Eandsburg, a large 

gold-producing camp, and Atolia are really parts of the same mineral-bearing area. The point may not be pressed too far, however, 

for there are numerous exceptions, such as the wolframite deposits 

found in connection with the gold deposits of Lead, S. Dak.

It is not yet possible to show that the tungsten minerals occur in one 

granitoid rock more than another, but they have not been found in 

rocks (such as the gabbros) that carry no free quartz that is, quartz 

occurring in grains through the rock.

The country rock cut by the granite has apparently something to 

do with the distribution of the deposits. Eocks that retain open
I TUNGSTEN DEPOSITS. . 37

spaces when cracked are the most congenial hosts. Schists under heat, 

pressure, and moisture seem to squeeze together too easily to make 

good places for veins to form.1 If conditions are favorable, however, 

veins of fair width and length may form in them, as near Hill City, 

S. Dak., and Yucca, Ariz., particularly if the veins cut across the 

schistosity that is, across the grain of the schist. Limestones make 

excellent hosts for veins, for besides being brittle and retaining 

cracks well they are easily replaced by other minerals. Most igneous 

rocks, such as dikes and other intruded masses, retain open cracks 

when broken, so that veins may form in them readily.

FORMS.

Tungsten deposits may be placed in six groups segregation deposits, pegmatite dikes, veins, replacement deposits, contact-metamorphic deposits, and placers. The deposits will be described in this 

order, which is, however, not the order of their importance but represents in general the way in which they grade into one another.

SEGREGATION DEPOSITS.

At some places the igneous rocks, rocks that were once molten, such 

as granite, contain a much larger proportion of certain minerals than 

at other places in the same body of rock, and such masses are known 

as segregations. Many of them contain the heavier minerals, among 

which may be tungsten minerals. It is as if a fruit cake before 

baking had been tipped to one end of the pan so that the raisins had 

settled at that end. Only one such occurrence of wolframite is 

known a deposit in the Whetstone Mountains, Cochise County, 

Ariz., 12 miles south-southwest of Benson. Here wolframite, in small 

flat crystals, is distributed through a very pure potash granite in 

irregular masses that lie close to small, irregular gash quartz veins.2 

A few tons of concentrates have been produced from the deposit. 

The ore is remarkably like some of that from a pegmatitic deposit on 

Blue Grouse Mountain, Stevens County, Wash. (See PI. XVIII, A.)

PEGMATITE DIKES. '

When masses of molten (igneous) rocks, such as granite, diorite, 

and related rocks, are forced toward the surface of the earth, they 

cool and freeze, or, in other words, become solid, just as water does 

when the temperature falls below 32° F. (0° C.). In cooling, the 

rocks shrink, new adjustments of position are made, and the mass is 

cracked. By the shrinkage of the mass, or by other forces, parts of

1 See appendix.

- Hess, F. L., Note on a wolframite deposit In the Whetstone Mountains, Ariz.: U. S. 

Geol. Survey Bull. 380, pp. 164-165, 1909.
38 TUNGSTEN MINERALS AND DEPOSITS.

the rock which are still molten, and which may contain large quantities of water, are forced up into the cracks, forming dikes.

Reverting to a figure already used, it may be said that pegmatites 

are formed somewhat like parts of a cake that is baked in too hot 

an oven. A crust is formed that shrinks and cracks, and the pasty 

central mass is forced up into the cracks. In a general way the minerals of the dikes resemble those of the surrounding rock mass. Thus 

most of the rocks that form dikes in granite contain potash feldspars, 

and most of those that form dikes in the less siliceous rocks contain 

soda or lime feldspars. Part of the dikes are coarse, uneven grained, 

and generally not homogeneous in composition, and these are known 

as pegmatites. Many pegmatites carry numerous rare minerals, 

among which may be tungsten minerals. These rare minerals are 

either lacking or present only in very small quantities in the parent 

mass, and the pegmatites may therefore be considered a type of 

segregation deposit. Scheelite is uncommon in pegmatites but has 

been found in them in small quantities. Near Oreville and Hill City, 

S. Dak., wolframite* is found in pegmatite, and specimens of wolframite from Blue Grouse Mountain, near Loon Lake, Stevens County, 

Wash., are embedded in a fine-grained pegmatite. (See PL XVIII, 

A.) Specimens of scheelite sent to the Survey by Margarito Romero 

from El Porvenir, El Porvenir district, N. Mex., are in a pegmatite 

gangue of quartz, feldspar, and fluorspar, and contain also molybdenum and copper minerals. Scheelite has been found in pegmatite 

on the north side of Tunk Pond, near Cherryfield, Maine. Specimens 

from a deposit near Rinconada, Rio Arriba County, N. Mex., which 

carry wolframite, with tourmaline, quartz, copper, and other minerals, are possibly from a pegmatite or a vein closely related to 

pegmatite.

Probably the most remarkable tungsten-bearing pegmatite known 

is that which contains the great cryolite deposit at Ivigtut, Greenland, in which is found a ferberite containing nearly 1 per cent of 

columbic and tantalic oxides.

Many quartz veins that carry tungsten minerals appear to be pegmatites from which most of the minerals have been frozen or precipitated at lower levels. Such are the veins at Hill City, S. Dak., 

some of which carry cassiterite (tin oxide, Sn02 ), apatite, mica, and 

a little feldspar in the quartz. On Irish Creek, Rockbridge County, 

Va., there is a deposit, generally called a vein, which shows some of 

the characteristics of a pegmatite. It carries cassiterite and wolframite in a gangue of quartz,. arsenopyrite, and pyrite, with beryl, 

muscovite (white mica), and probably other minerals.

A vein system near Pony, Mont., that carries hiibnerite grades into 

pegmatite.1 Some of the tin-bearing and tungsten-bearing veins of

1 Winchell, A. N., Mining districts of the Dillon quadrangle, Mont., and adjacent areas: 

U. S. Geol. Survey Bull. 574, p. 125, 1914.
,y --

-X^fe^^~^^?^^Vv^ ^r^4^M;;: ^^/;ir4^

 £ ^"'\' '" *

"../,'-<,,^ J >"''

^. POLISHED SPECIMEN OF FINE-GRAINED PEGMATITE CARRYING WOLFRAMITE, FROM BLUE

GROUSE MOUNTAIN, STEVENS COUNTY, WASH. 

Natural size. The wolframite is in thin, broad plates, only the edges of which show.

B. POLISHED SPECIMEN OF PEGMATITE WITH FERBERITE, CUTTING GRANITE, FROM CAVE

CREEK, ARIZ. 

Three-fifths natural size. The pegmatite runs from left to right and grades into the granite on both sides.
U. S. GEOLOGICAL SURVEY

POLISHED SPECIMEN FROM HUMBUG MINING DISTRICT, YAVAPAI COUNTY, ARIZ., SHOWING 

ANASTOMOSING WOLFRAMITE VEINLETS,

Natural size. Lighted so thatthe wolframite appears white in the largest vein (at the right). A vug into 

which wolframite crystals grew has been filled with hydrous iron oxide (black).
TUNGSTEN DEPOSITS. 39

Cornwall are much like pegmatites. Thus the veins of the East Pool 

and adjoining properties at Carn Brea, Cornwall, carry " remarkable 

intergrowths of wolframite, pyrite, arsenopyrite, quartz, and microcline," * a mixture of minerals which might well be pajt of a pegmatite dike. The wolframite-bismuth deposits at Torrington, New 

South Wales, seem to be in part pegmatites, in part replacement deposits in granite, and in part veins connected with or proceeding 

from the pegmatites. 2

At Mount Carbine, Queensland,3 " Some parts of the veins are 

chiefly composed of feldspar, * * * [though] from end to end it 

will probably not exceed 10 per cent, while it may.be as low as 5 

per cent of the whole gangue." The veins also contain some mica 

and tourmaline, the tourmaline generally invisible to the unaided 

eye, and altogether the veins seem not many degrees removed from 

pegmatite dikes.

So far no large production has been made in the United States 

from deposits that are essentially pegmatitic.

VEINS.

Veins are relatively thin bodies that fill cracks in rocks and have 

been deposited from solution. Most of them are different from 'the 

rocks that form their walls. Such are the familiar quartz and calcite veins.

All the tungsten minerals have been found in veins and most tungsten deposits are of this form. The tungsten minerals are accompanied by a considerable variety of others, though as a rule not many 

of them occur in any one vein. In known veins the following minerals are associated with tungsten minerals: Adularia, ankerite, apatite, arsenopyrite, beryl, bismuth, 'bismuthinite, calcite, cassiterite, 

chalcopyrite, chalcocite, chlorite, cinnabar, cosalite, covellite, dolomite, 

fluorspar, gahiiite, galena, gold, graphite, hamlinite (?), lepidolite, 

molybdenite, muscovite (including sericite), pyrite, quartz, siderite, 

silver, specularite, sphalerite, stibnite, sylvanite and related minerals, 

triplite, tourmaline, and topaz, and oxidized veins in which stolzite is 

found contain vanadinite, endlichite, pyromorphite, and other oxidized minerals. Some wolframites carry within themselves tantalum, columbium, and scandium, and some scheelites carry small 

quantities of molybdenum and the rare-earth metals.4

This list includes a number of unusual vein minerals, some of 

which beryl, cassiterite, tourmaline, apatite, muscovite, fluorspar,

1 Dewey, Henry, and others, Tungsten and manganese ores : Great Britain Geol. Survey 

Mem., Special reports on the mineral resources of Great Britain, vol. 1, p. 20, 1915.

2 Game, J. E.. The tungsten mining industry in New South Wales: New South Wales 

Geol. Survey Mineral Resources No. 15, pp. 33-46, 1912.

3 Ball, L. C., The wolfram mines of Mount Carbine: Queensland Geol. Survey Pub. 251, 

pp. 31-32, 1915. 

* See appendix.
40 TUNGSTEN MINERALS AND DEPOSITS.

molybdenite, topaz, tantalum, and columbium suggest connection 

with pegmatites, so' that it is not suprising to find that some tungstenbearing quartz veins are really pegmatites from which most or all 

of the feldspar and most of the mica have probably crystallized at 

greater depths, as noted on page 38.

A tungsten vein may show all the vagaries of other veins. It may 

be a single simple veinlet of "knife-edge" thickness, or a single 

vein many feet wide, or it may consist of compound veins with many 

anastomosing (interlacing) veinlets (see PL XIX) or criss-crossing 

veins, some of them several inches wide, or it may consist of short 

" stepped" veins that form one series which is yet not continuous. 

It may swell or pinch to a stringer, or it may disappear entirely 

for a distance. The minerals in a vein are generally in shoots of 

more or less good ore alternating with barren parts. This variation, 

however, is not peculiar but is a characteristic of most if not all 

veins of metallic minerals. The occurrence of shoots in gold, silver, 

and other veins is familiar to miners and prospectors.

Most tungsten veins have a quartz filling in which the tungsten 

minerals are embedded, but some, such as the thin veins in the Boulder 

field, carry comparatively little quartz; most of the vein is ferberite. 

In fact, ordinary white quartz is so scarce in these veins that miners 

have sent specimens to the Geological Survey as curiosities, a greatly 

appreciated courtesy. 1 In the deposits at Atolia, Cal., also, there is 

comparatively little quartz; calcite carrying some iron is the principal gangue mineral. A vein may solidly fill the space between its 

walls or it may contain numerous hollows, known as vugs.2 The 

vugs are generally lined with crystals (PI. XIX) formed of the 

mineral last deposited in the vug. In the Boulder field some vugs 

are lined with beautiful crystals of ferberite; others are lined with 

chalcedony and opal. A few vugs in the same field are lined or filled 

with scheelite. In other fields the vugs are lined with quartz, calcite, 

hiibnerite, or other minerals, in many places coated with silica. Vugs 

that were once lined with wolframite, scheelite, or other crystals have 

been filled by other minerals as deposition proceeded and are now 

parts of a solid vein.

REPLACEMENT DEPOSITS.

The rock in an area where veins traverse easily soluble rocks is 

commonly replaced by the vein matter, and the replacement may 

be so complete and extensive as to obliterate all trace of the original 

opening through which the solutions passed, and such bodies are 

naturally called replacement deposits.

1 See appendix.

2 Vug is an old Cornish word coined by miners to mean just this thing. The term, 

although well known to most miners, is calle.cl by some " vug holes " ; by others, who 

have evidently in the first place misunderstood the word, " bug holes."
TUNGSTEN DEPOSITS. 41

Certain rocks are rather easily dissolved in the solutions from 

which tungsten and other minerals are deposited, particularly rocks 

that are largely or wholly made up of carbonates, such as limestone, 

which is more or less pure calcite,v calcium carbonate; dolomite, the 

magnesium-calcium carbonate; and siderite, the iron carbonate. 

Under certain conditions other rocks are also fairly soluble. Generally, however, a sedimentary rock that has been extensively replaced 

naturally creates the impression that it probably was a rock containing a large percentage of carbonates.

At Lead, S. Dak., wolframite was apparently brought from the 

depths by solutions that flowed through thin cracks known as " verticals." Where the solutions reached a bed of dolomite they spread 

out through the rock, replacing it and depositing wolframite and 

small quantities of scheelite, gold, silver, pyrite, and other minerals. 

Many fragments of shells of Cambrian age are preserved in the 

ore. (See PI. X, B.) Local variations in the rock made variations 

in the outline of the ore body, but at most places it is rounded and 

bulbous.

Granitic rocks may be replaced in much the same way, though most 

of the known replaced bodies are much smaller. Plate XVII, A, 

shows a specimen from the claims of the Pittsburgh Tungsten Mines 

Co., at Cave Creek, Ariz., furnished by the courtesy of Mr. S. H. 

Brockunier. In this specimen a micaceous phase of a granite has 

been in part replaced by cuprotungstite and ferberite. The ferberite 

looks like drops of ink in a blotter; if the blotter instead of being in 

a thin sheet were in the form of a block, so that the ink could spread 

equally through three dimensions, the comparison would be very 

close.

Such deposits, on account of the exceptional conditions required 

for their formation, are naturally unusual. In this country only 

those in the vicinity of Lead, S. Dak., have so far been productive. 

They have paid considerable profits on their exploitation during 1915 

and 1916. The scheelite deposit at Long Hill, near Trumbull, Conn., 

is in many ways similar. At this place a greatly metamorphosed 

limestone, lying between gneisses, which, Hobbs x calls diorite but 

which may be highly metamorphosed tuffs, contains replacement 

bodies now composed of quartz, zoisite, epidote, and other minerals 

with which is associated nearly white scheelite. These replaced 

bodies are more or less closely connected with thin vertical veins, as 

are the Lead deposits, and pegmatites cut the same rocks.

As a matter of fact, however, the larger veins of ferberite in 

Boulder County, Colo., and the wider scheelite veins at Atolia,1 Cal., 

are replacement bodies, for the crevices which existed when the veins

1 Hobbs, W. H., The old tungsten mine at Trumbull, Conn.: TJ. S. Geol. Survey Twentysecond Ann. Kept., pt. 2, p. 16, 1901.
42 TUNGSTEN MINERALS AND DEPOSITS.

were formed were probably rather narrow, and much of the finegrained quartz (see PI. XXIV, A) found in both sets of veins has 

probably replaced granite or granodiorite.

In Cornwall, Saxony, and other places where tin and tungstenbearing veins are found granite is altered to greisen x in considerable 

bodies. Here the original quartz is probably left, but the feldspars 

have been removed by hot ascending solutions, which have replaced 

them by quartz, mica, cassiterite, and wolframite. Similar deposits 

are found near Torrington, New South Wales, and the descriptions indicate to the writer that they are of similar origin, though J. E. Carne 2 

and E. C. Andrews do not seem to think so. No large deposits of this 

sort are known in the United States, .but similar conditions are 

found on a small scale in the pegmatites near Hill City, S. Dak., 

where solutions carrying quartz, wolframite, and possibly cassiterite 

and muscovite (white mica) have here and there replaced parts of 

the dike, probably only a short time after it had hardened.

Pegmatite pipes crooked, roughly cylindrical bodies of pegmatite are another form of replacement bodies in granite. Wolframite 

deposits are found in such forms in Queensland 3 and New South 

Wales.4 Though not now known in this country, they may yet be 

discovered.

CONTACT-METAMORPHIC DEPOSITS.

When granitic rocks or their porphyritic variants are intruded 

into some kinds of sedimentary rocks, particularly limestones or 

dolomites, the hot water which accompanies the intrusive rock and 

probably comes from it, and which is loaded with much mineral 

matter in solution, attacks the country rock and may alter or metamorphose it until it loses all semblance to the original rock, though 

to the trained eye the altered appearance usually suggests the original 

rock and the process through which it has passed. In many places 

the original carbonate of lime or the dolomite are in part removed, 

a part is recrystallized and remains, and another part combines with the mineral matter introduced in solution from the intrusive rock and forms new minerals, such as garnet, vesuvianite, epidote, zoisite, hornblende, and tremolite. Other new minerals form 

from the clay, iron, and other impurities contained in the limestone 

and the mineral matter of the intrusive water, and still others, such

1 Greisen, as the word was originally used, is rock composed of quartz and lithium 

mica, but the term is ordinarily used to mean any silicifled granitic rock containing more 

or less mica.

2 Carne, J. E., The tungsten-mining industry in New South Wales : New South Wales 

Geol. Survey Mineral Resources 15, pp. 33-46, 1912.

3 Ball, L. C., Rare-metal mining in Queensland; Re"sum<5 of recent field studies : Queensland Government Min. Jour., vol. 14, pp. 4-7, 1913.

* Andrews, E. C., The geology of the New England Plateau [New South Wales], with 

special reference to the granites of northern New England : New South Wales Geol. Sur-J 

vey, vol. 8, pt. 2, pp. 138-141, 1905.
TUNGSTEN DEPOSITS. 43

as pyrite, chalcopyrite, and magnetite, crystallize from the solution 

and occupy spaces in the formerly solid limestone. Rocks so altered 

are called contact-metamorphic rocks and the volumes so altered are 

known as zones, because they usually form more or less irregular 

bands around the intrusive mass. Not only is the limestone metamorphosed by the contact with the heated waters issuing from or 

with the intrusive mass, but the intrusive itself may be altered, 

though in less degree, by the introduction of other minerals, particularly lime taken by the water from the surrounding rocks. 

Specimens from deposits 15 miles northwest of Seven Troughs, Nev., 

show granite thus replaced by epidote, scheelite, and other minerals. 

The acquirement of mineral matter from the country rock by the 

intrusive is also shown by the presence of graphite in pegmatite dikes 

cutting graphitic schists near Hill City, S. Dak., and in veins that 

are probably extensions of pegmatite dikes.

Among the less common minerals deposited from intrusive water 

is scheelite. It is distributed through the rock and may occur in 

kernels ranging in size from-^of an inch (0.1 millimeter) to several inches (a decimeter or more) in diameter but that are commonly 

less than half an inch fl (l centimeter) in diameter.

Contact-metamorphic deposits have been found at the south end of 

the Trinity Range near Browns (Toy) and in adjacent areas in 

Humboldt County, and near Montgomery, Mineral County, Nev.; in 

the Grouse Creek Range, Box Elder County, 15 miles north of 

Lucin, and in the Deep Creek Mountains, Tooele County, Utah; west 

and south of Bishop, Inyo County, Cal.; in the Apache No. 2 mining 

district, 6 miles south-Southeast of Hachita, N. Mex. Specimens from 

a point near Weldon, Kern County, Cal., are evidently from contactmetamorphic deposits. Some of the deposits near Browns have been 

actively exploited, and a small production has been made from the 

others. In a specimen from one of the claims near Browns the 

scheelite occurs in particles ^g- to -fa of an inch (0.1 to 0.7 millimeter) in diameter, so small that they can not be distinguished by 

the unaided eye from the brownish mixture of minerals making up 

the rock. In another specimen the grains are the size of small peas. 

In the Grouse Creek Mountains the grains are half an inch (1 centimeter) or more in diameter and are comparatively easy to recognize. 

In the Deep Creek Mountains some of the masses are as large as a 

man's fist or larger.1 On Cape Mountain, near Cape Prince of 

Wales, Alaska, Knopf 2 found a little scheelite in microscopic particles in contact-metamorphosed limestone.

Some deposits in contact-metamorphosed rocks may have remained 

undiscovered, because tlie scheelite is so fine grained that it has

* B. S. Butler, personal communication.

2 Knopf, Adolph, Geology of the Seward Peninsula tin deposits: U. S. Geol. Survey 

Bull. 358, pp. 24, 30, 31, 1908.
44 TUNGSTEN MINERALS AND DEPOSITS.

escaped notice, and in others, such as part of those near Bishop, the 

scheelite grains are comparatively small and so white that they would 

ordinarily be mistaken for calcite. But scheelite is not a common 

mineral in such rocks, for though hundreds of specimens from many 

parts of the United States have been examined microscopically at the 

Geological Survey, the only specimen that contained it was that from 

Cape Mountain, Alaska, a locality to which reference has just been 

made. Deposits near Browns and Toulon, Nev., and Bishop, Cal., 

are being actively exploited on a large scale, though except at 

Browns the developments are all new. Similarly metamorphosed 

rocks worked for gold by the Seoul Mining Co. on the Suan concession, Chosen (Korea), carry scheelite in crystals as much as 2 inches 

thick.1

PLACERS.

As the earth's features are worn away by the action of water, by 

changes in temperature from cold to hot and hot to cold and by 

wind and the other agencies of destruction, minerals are broken out 

of the exposed parts of veins and become mingled with fragments of 

the country rocks to form the debris slopes of the hills, whence they 

are gradually moved by gravity, water, wind, and frost into the 

gravel deposits of the valleys. It is generally known that gold 

placers are formed in this way, but the similar formation of tungsten 

placers has apparently not been so generally recognized. Scheelite 

has been found in gold placers near Nome, and wolframite in gold 

placers near Circle, Alaska. Tungsten minerals, mostly wolframite, 

are found with stream tin in placers, from which production has been 

made in Siam, the Malay Peninsula, Banka, and Billiton; scheelite 

has been found in gold placers in the Caribou district, British Columbia, and wolframite placers have been exploited on the Bodmin 

Moors, Cornwall, England; 2 and examples might be multiplied.

The first scheelite produced at Atolia, Cal., was float material 

picked up in the desert sands. Some scheelite has been dug from 

Baltic Gulch, between Atolia and Bandsburg, for several years, and 

during the last year considerable quantities have been mined from 

the desert debris of the region. , In Boulder County, Colo., a large 

quantity of float ferberite has been dug from the dirt near the outcrops of the tungsten veins. Not until the high prices of 1915 and 

1916 gave the great impetus to tungsten mining, however, was there 

very extensive placer mining for tungsten in this country; then it 

was taken up with enthusiasm in Arizona, California, Nevada, and 

Colorado. Some of the residual pieces of scheelite found near Atolia 

have been large, one is reported to have weighed more than 100

1 Oral communication' from J. P. Manning and E. W. Mills.

2 Dewey, Henry, Tungsten and manganese ores : Great Britain Geol. Survey Mem., Special reports on the mineral resources of Great Britain, vol. 1, pp. 33-35, 1915.
U. S. GEOLOGICAL SURVEY

A. PART OF A FERBERITE PEBBLE FROM NEDERLAND, COLO.

B. SCHEELITE PEBBLE FROM BALTIC GULCH, BETWEEN RANDSBURG AND ATOLIA, CAL. 

 C. RESIDUAL SCHEELITE PEBBLE COATED WITH CALICHE (CALCIUM CARBONATE), FROM

ATOLIA, CAL.

All natural size
U. S. GEOLOGICAL SURVEY 

/*" * 

L

fc

i&m** v, ' **- - -*--* ' < 

HUBNERITE-BEARING QUARTZ VEIN IN QUARTZ-MICA SCHIST, FROM TUNGSTEN 

Nearly natural size. Showing distribution of hubnerite in the vein and pyrite in the country rock. Owing to poor lig
TUNGSTEN DEPOSITS. 45

pounds and at the prevailing prices in the spring of 1916 was worth 

several hundred dollars. The residual pieces found near Atolia are 

covered with caliche calcium carbonate, much like a spring deposit. 

(See PL XX, G.} Most of the pieces found in the watercourses, 

even in the infrequently wet stream beds of the desert, are clean 

(see PL XX, #), and many of the scheelite pebbles- from the Nome 

placers are crumbly, showing that they are gradually being dissolved. 

A part of a ferberite pebble from Nederland, Colo., is shown in 

Plate XX, A'

TUNGSTEN VEINS. 

MINERALS.

As already stated a considerable number of minerals are found 

in tungsten-bearing veins. ' Brief descriptions of the principal minerals that have been so found not the detailed descriptions demanded by the mineralogist are given below in the hope that some 

of them may be of use to prospectors and miners.

The minerals are in general grouped after the plan used in the 

sixth edition of Dana's " System of mineralogy."

NATIVE ELEMENTS.

Bismuth. Bismuth is a bright tin-white metal, very brittle, easily 

cut with a knife, and easily melted (melting point, 270° C. or 518° F., 

considerably below a red heat). It changes under the influence of 

the atmosphere to the hydrous oxide, bismuth ocher, and to carbonate, both of which may be white but are generally yellow, probably ,from iron, and may be green from copper. Bismuth is not 

found in large quantity in the tungsten deposits of the United States, 

but is common in some of the foreign deposits, particularly those 

of Queensland.1

In this country bismuth is found in wolframite deposits in the 

Eureka district, 45 miles west of Prescott, Ariz. Oxidized bismuth 

minerals are found with scheelite 3 miles north of the Dona Ana 

County line, 37 miles west of Tularosa, K Mex.; in the Euby Mountains, 10 miles south-southwest of Euby Valley post office, Elko 

County, Nev. ; 2 and with wolframite in the Hachita district near 

Gage, N. Mex.

Gold. Gold is found in many tungsten-bearing veins, but seems 

to be associated with scheelite more commonly than with the wolframites. Gold is found with scheelite in the Union Hill and Empire 

mines at Grass Valley, CaL, and in specimens from the Union Hill

1 Ball, L. C., Rare metal mining in Queensland ; Re'sume1 of recent field studies: Queensland Government Min. Jour., vol. 14, pp. 4-7, 1913. Cameron, W. E., Wolfram and molybdenite mining in Queensland: Queensland Geol. Survey Rept. 188, p. 13, 1904.

2 Hill, J. MM Notes on some mining districts in eastern Nevada: U. S. Geol. Survey 

^Bull. 648, pp. 62-63, 1916.
46 TUNGSTEN MINEBALS AND DEPOSITS.

mine gold can be seen in narrow quartz veinlets cutting the scheelite, 

though not in the scheelite itself. At Randsburg, Cal., scheelite is 

found in many of the gold veins; at Murray, Idaho, and Amalie, 

Cal., scheelite has been mined with gold-bearing galena and pyrite. 

(See PI. XI, A.) At Leadville scheelite and less wolframite are 

found in a quartz-pyrite vein carrying 0.8 ounce of gold and 0.5 ounce 

of silver to the short ton of ore.1 (See PI. XIV, A.) Gold is found 

in scheelite-bearing quartz veins in the Sheepeater district, near Jardine, Park County, Mont. (PI. XII, B) ; near Baker City, Oreg.; at 

Oracle, Ariz., where the veins are worked for both gold and scheelite; 

and in other places. At Hillgrove, New South Wales, and MacRaes 

Flat, New Zealand, veins have been worked for both scheelite and gold. 

Gold has been reported in hiibnerite deposits at Tungsten, 12 miles 

south of Osceola, Nev.; Patterson Creek, Idaho; White Oaks, N. Mex. 

(PI. V, B) ; and Silverton, Colo. (PL IV, B) ; with wolframite in the 

Hachita district, N. Mex., and at Lead, S. Dak. (PI. X, B) ; with ferberite at Cave Creek, Ariz.; and some of the ferberite veins in Boulder 

County, Colo., carry a little gold. The gold and tungsten minerals 

in many of these deposits may have been deposited at different times.2 

Graphite. Graphite, familiar to all in lead pencils, as a lubricant, 

and in stove polish, is one of the forms of carbon. It is found in 

wolframite-bearing quartz veins on the May Day and Vida May 

claims near Hill City, S. Dak. The veins are closely related to 

pegmatites and cut graphitic schists, from which the graphite has 

been concentrated in the veins and in the walls next to the veins.

SULPHIDES, ARSENIDES, ANTIMONIDES, AND TELLUBIDES.

Arsenopyrite. Arsenopyrite (FeAsS), the arsenide and sulphide 

of iron, a silvery-white mineral, is not found in many American 

tungsten deposits. It occurs with wolframite on Irish Creek, Rockbridge County, Va.; in small quantity with the wolframite at Lead, 

S. Dak.; and in the Etta dike at Keystone, S. Dak. It is reported 

in Bolivian ores and is common in the wolframites from tin mines.

Bismuthinite. Bismuthinite, bismuth sulphide (Bi2S3 ), a lead- 

' colored to tin-white mineral that has one excellent cleavage, is generally found in those tungsten deposits which carry other bismuth 

minerals. It is easily cut with a knife. Most buyers object to bismuth minerals in tungsten ores, though others who use different 

processes of reduction raise no objection to them.

Chalcocite. Chalcocite, copper glance (Cu2S), a dark-gray to 

nearly black mineral, is found in only a few tungsten veins. It has 

been noted at Patterson, in the Blue Wing district, Lemhi County,

1 Fitch, R. S., and Loughlin, G. F., Wolframite and scheelite at Lead,ville, Colo.: Econ. 

Geology, vol. 2, pp. 30-36, 1907.

2 See appendix.
TUNGSTEN DEPOSITS. 47

Idaho,1 and with wolframite in Powers Gulch, 18 miles west of Globe, 

Ariz. At Butte, Mont., hiibnerite is found in copper deposits that 

carry great quantities of chalcocite, and at Woody, Cal., a wolframite 

that is possibly ferberite is found in gold-bearing copper deposits 

that carry chalcocite.

Chalcopyrite. The copper-iron sulphide, chalcopyrite (CuFeS2 ), 

a bright brassy-yellow mineral, is found in many tungsten deposits. 

The presence of copper in tungsten minerals, like that of bismuth, is 

objected to by some buyers but not by others, the preference of the 

buyer depending on the process of reduction he uses.

Cinnabar. Cinnabar, mercury sulphide (HgS), a beautiful vermilion-colored mineral, has been found in only a few tungsten deposits. John H. Williams sent to the Survey specimens from the 

Jack claim in the Clark Mountains, eastern San Bernardino County, 

Cal., showing cinnabar in the middle of a thin wolframite vein (PI. 

V, 4), and specimens of wolframite from the Tip Top district, 

Yavapai County, Ariz., contain tiny specks of cinnabar. The cinnabar in the specimens from the Clark Mountains, San Bernardino 

County, Cal., was deposited after the. wolframite had been formed, 

possibly at a very much later time.

Cosalite. The bismuth-lead sulphide known as cosalite occurs as 

a tin-white fibrous, metallic mineral, in hiibnerite deposits 5 or 6 

miles northeast of Loon Lake, Stevens County, Wash., in the^SE. £ 

sec. 16, T. 30 N., E. 42 E., where it contains about 0.8 of 1 per cent of 

silver. It weathers to a buff-yellow oxide.

Covellite. The copper sulphide, covellite (CuS), a beautiful 

bluish mineral formed by the alteration of chalcopyrite, is found in 

the oxidized and in the enriched parts of deposits that carry chalcopyrite.

Galena. Galena, lead sulphide (PbS), though by no means a 

common mineral in tungsten deposits, is found in a number of veins. 

When fresh it has an almost silvery metallic luster, which changes 

on exposure to the air to " lead gray." It has good cleavages in three 

. directions at right angles to each other, so that it may be cleaved 

into cubes. It is easily cut with a knife and is very heavy, having a 

specific gravity of 7.4 to 7.5. Galena is found with hiibnerite at 

Silverton, Colo.; in small quantity with hiibnerite at Tungsten, 12 

miles south of Osceola, Nev., and on Patterson Creek, Idaho; and 

with wolframite near Pioche, Nev., and Silvermine, Mo. In the 

ferberite veins on the edges of the Boulder field in Colorado a little 

galena is found. It occurs with scheelite in the Golden Chest mine 

at Murray, Idaho (PI. XI, A) and at Covada, Wash.

^/0Zy&^<m«'fe. Molybdenite, molybdenum sulphide (MoS2 ), a lustrous metallic lead-gray mineral, occurs in lumps or thin flakes that

1 Umpleby, J. B., Geology and ore deposits of Lemhi County, Idaho: U. S. Geol. Survey 

Bull. 528, p. Ill, 1913.
48 TUNGSTEN MINEEALS AND DEPOSITS.

tend toward six-sided forms. The lumps are easily cleavable with 

the finger nail into thin leaves, which are flexible but not elastic and 

mark paper similarly to graphite, though with an olive-green tint. 

Molybdenite has been found With wolframite near Daisy, Wash., 

with ferberite at Cave Creek, Ariz., and with scheelite in the Deep 

Creek Mountains, Utah.

On Lost River, Alaska, wolframite and molybdenite are found in 

closely associated veins, though they are not known to be mixed together in the same vein. Molybdenite and scheelite, the molybdenite 

largely altered to powellite, occur together at Oak Springs, Nye 

County, Nev., and in the vicinity of Black Mountain, 15 or 20 miles 

northwest of Randsburg, CaL, but the deposits have so far not proved 

to be commercially valuable.

Pyrite. The yellow iron sulphide, pyrite (FeS2 ), is common in 

veins formed at all depths and, as would be expected, it is found in 

most tungsten veins, though in many of them it occurs only in small 

quantity. Some deposits, such as the scheelite veins of Atolia, CaL, 

and the ferberite veins of Boulder County, Colo., are remarkably 

free from pyrite.1 In some veins pyrite forms in greater quantity in 

the country rock than in the vein itself. Plate XXI shows a part 

of a hiibnerite-quartz vein near Deer Park, Wash., in which pyrite 

in cubical crystals occurs in the country rock but not in the vein. 

Some specimens from the vein, however, contain cubes of pyrite an 

inch square. The scheelite from Leadville (PI. XIV, A] is accompanied by large crystals of pyrite formed in a vug, but pyrite usually 

occurs in irregular masses.

Silver minerals. The form in which silver occurs in most tungsten-bearing veins is obscure. It is probably never native except in 

the oxidized or enriched parts of veins or where it is alloyed with 

gold, and in most deposits it is probably combined with sulphur or 

other elements. In deposits at Loon Lake, Wash., it occurs in cosalite; 2 at Patterson, Idaho, in tetrahedrite,3 of which it forms 1.9 

per cent; at Silvermine, Mo., in argentiferous galena; and in the 

contact-metamorphic deposits in the Apache No. 2 district, near 

Hachita, N.. Mex., as horn silver.4 As already noted, silver seems to 

occur more plentifully with the wolframites than with scheelite.

/Sphalerite. The zinc sulphide, sphalerite (ZnS), is found in 

only a few tungsten-bearing veins in the United States,1 though it 

is reported from tungsten veins in England.5 It is found in hiib1 See appendix.

2 Bancroft, Howland, Ore deposits of northeastern Washington : U. S. Geol. Survey Bull. 

550, p. 132, 1914.

3 Umpleby, J. B., Geology and ore deposits of Lemhi County, Idaho : U. S. Geol. Survey 

Bull. 528, p. Ill, 1913.

4 Lindgren, Waldemar, The ore deposits of New Mexico : U. S. Geol. Survey Prof. Paper 

68, p. 343, 1910.

B Dewey, Henry, and others, Tungsten and manganese ores: Great Britain Geol. Survey 

Mem., Special reports on the mineral resources of Great Britain, vol. 1, pp. 24, 37, 38, 

1915.
TUNGSTEN DEPOSITS. 49

nerite veins at Patterson, Idaho, and resembles the hubnerite so closely 

that the two are difficult to distinguish by their appearance alone, 

but the streak of the sphalerite is gray and that of the hiibnerite is 

brown.1

The thin quartz veins at Long Hill, Trumbull, Conn., contain a 

black sphalerite which is difficult to distinguish by its outward appearance from wolframite. Its specific gravity, however (about 4), 

is much less than that of wolframite (7.2 to 7.5), its streak is light 

brown, and when the sphalerite is heated it turns buff.

Another zinc mineral, the spinel, gahnite (a zinc aluminate, 

ZnAl204 ), is found, in quartz veins with wolframite and cassiterite 

in the Tin Mountains, Stewart Island, New Zealand,2 but is not 

known in the tungsten veins of this country.

Stibnite. Stibnite, antimony sulphide (Sb2 S3 ), is a soft, lustrous 

metallic gray mineral, which may be scratched with a hard finger 

nail. It has one excellent cleavage plane, so that when freshly broken 

it shows bright, shining faces. The crystals are generally needleshaped, though they may be short and as broad as long. Stibnite 

occurs with scheelite at places, but has rarely been found with the 

wolframites. At Atolia, Cal., a little stibnite is found with scheelite 

and in the quartz gangue there are slender cavities^ 3 inches by oneeighth inch, which are now nearly filled with pinkish quartz but 

which apparently were once occupied by stibnite. (See PL XXII.) 

Similar cavities in a specimen from the Hachita mining district, 

near Gage, N. Mex., were so well preserved that the angles of a wax 

impression could be measured with considerable accuracy, and Dr. 

E. T. Wherry found that they had the angles of stibnite crystals. 

Stibnite and scheelite are found together at Hillgrove, New South 

Wales; 3 on Stony Creek, 9 miles from Waipori, New Zealand; 4 and 

at Genna Gureu, Italy.5 Stibnite, largely altered to oxide, has been 

found in the middle of a wolframite vein an inch wide in the Clark 

Mountains, San Bernardino County, Cal. A similar association has 

been reported from the Tip Top district, Yavapai County, Ariz., 

but the report is unconfirmed. At. the Pucka antimony mine, 

Lionsville, New South Wales, a vein of mixed wolframite and 

stibnite has been worked.6

1 Umpleby, J. B., op. cit, p. 111.

2 McKay, Alexander, On the geology of Stewart Island and the tin deposits of Port 

Pegasus district: New Zealand Colonial Mus. and Geol. Survey Rept. Geol. Bxpl. during 

1888-89, p. 84, 1890.

8 Longbottom, W. A., Scheelite mining; Occurrence and treatment In New South Wales: 

Min. and Eng. Rev., vol. 3, pp. 199-200, Sydney and Melbourne, 1911.

* Finlayson, A. M., The scheelite of Otago: New Zealand Inst. Trans. and Proc., vol. 40, 

p. 112, 1908.

6 Lovisato, Domenlco, Glacimento di mineral! di tungsteno a Genna Gureu ai limit! fra 

Nurri ed Orroli (Cagliari) : R. accad. Lincei Atti, ser. 5, vol. 16, pt. 1, pp. 632-638, 1907.

6 Carne, J. B., The tungsten mining industry: New South Wales Geol. Survey Mineral 

Resources No. 15, pp. 63-64, 1912.

47154° Bull. 652 17 4
50 TUNGSTEN MINERALS AND DEPOSITS.

At all these places the stibnite was probably introduced into the 

veins before or after the tungsten minerals were deposited.

Sylvanite. Sylvanite,gold-silver telluride [(Au,Ag)Te2 ], is found 

in some of the ferberite veins in the Boulder field, in Colorado, 

mostly around the outer edges of the field, where the gold veins and 

ferberite veins come together. In this field veins carrying both 

minerals have been found at Magnolia, in the Wheelmen tunnel in 

Boulder Canyon, and at Sunshine.1

Ccdaverite. At Cripple Creek, where gold is found combined with 

tellurium in the mineral calaverite, which contains less silver than 

sylvanite, some hiibnerite has been found in the Puzzle vein. 2

Tetrahedrite. Tetrahedrite is a mineral of variable chemical composition. In its simplest form it is a copper sulphantimonide 

(Cu8Sb2S7 ). Some tetrahedrites contain less antimony and copper 

than is indicated in the formula; they contain instead one or more 

of the elements arsenic, iron, silver, mercury, zinc, lead, bismuth, 

cobalt, and nickel. Tetrahedrite is a metallic, steel-gray to dark-gray 

or iron-black massive mineral with no cleavage; it breaks with an 

uneven surface. Its hardness ranges from 3 to 4.5. Its streak is of 

nearly the same color as the mineral itself but has a brownish or 

reddish tint.

It is found with hiibnerite at Patterson, Lemhi County, Idaho, 

and at Spanish Springs, 7 miles southeast of Manhattan, Nev.

Tetrahedrite on weathering makes green and blue copper stains 

as do other copper minerals.

FLUORIDES.

Fluorite, or fluorspar,'the calcium fluoride (CaF2 ), is colorless and 

transparent, pink, lilac, amethystine, dark purple, green or black. 

It has a hardness of 4, is easily scratched with a knife, but will 

scratch calcite. In many places it crystallizes in cubes. It has a 

perfect cleavage in eight directions, which allows it to be split into 

an octahedron. Its streak is white. When heated gently it glows 

beautifully. Hiibnerite is found with colorless fluorite at White 

Oaks, N. Mex., and Silvertori, Colo.; with lavender-colored fluorite 

on the west side of the Desatoya Mountains, and with deep amethystcolored fluorite at the old mining camp of Ellsworth, in northwestern 

Nye County, Nev. Colorless, green, and deep amethystine fluorite 

are found with wolframite on Tin Creek, a tributary of Lost River, 

110 miles northwest of Nome, Alaska. Fluorite, in part white and 

in part black, is found with ferberite at Cave Creek, Ariz. Fluorite 

is of common occurrence with the wolframites, but it is known to 

occur with scheelite at only one locality, the El Porvenir district, 18

1 See appendix.

2 Lindgren, Waldemar, and Ransome, F. L. ? Geology and gold deposits of the Cripple 

Creek district, Colo.: U. S. Geol. Survey Prof. Paper 54, p. 127, 1906.
U. S. GEOLOGICAL SURVEY BULLETIN 652 PLATE XXII

B

A. IRREGULAR MASSES OF STIBNITE IN QUARTZ GANGUE OF SCHEELITE VEIN, ATOLIA, CAL.

B. CAVITIES FORMERLY FILLED BY SLENDER CRYSTALS OF STIBNITE, NOW PARTLY FILLED

BY PINKISH QUARTZ, IN QUARTZ GANGUE OF SCHEELITE VEIN, ATOLIA, CAL.

Both natural size.
U.S. GEOLOGICAL SURVEY BULLETIN 652 PLATE XXI I

A. HYDROUS IRON OXIDE REMAINING AFTER DECOMPOSITION OFFERBER1TE FROM GOOD LUCK

CLAIM, NEAR HILL CITY, S. DAK.

B. WOLFRAMITE (BLACK) AND CASSITERITE (GRAYISH BROWN) IN QUARTZ FROM BLACK METAL 

CLAIMS, NEAR HILL CITY, S. DAK.
TUNGSTEN DEPOSITS. 51

miles northwest of Las Vegas, N. Mex., where green, white, and 

amethystine fluorite is found with scheelite. .

Other fluorides are discussed under tourmaline, lepidolite, and 

topaz, of the silicates, and apatite and triplite, of the phosphates.

OXIDES.

Cassiterite. Tin oxide (SnO2 ) accompanies wolframite at very 

few places in the United States, but wolframite and, to a less extent, 

scheelite are common in tin veins. Cassiterite is about as hard as 

quartz, has a greasy luster, and is generally dark rosin-brown or 

nearly black, though exceptionally it is colorless, translucent white, 

creamy, gray, pinkish, or ruby-colored. It has a glassy fracture, 

and a very few specimens show a noticeable cleavage.

Cassiterite is found with wolframite in quartz veins near Hill City, 

S. Dak. (see PL XXIII, #), with wolframite and arsenopyrite on 

Irish Creek, Rockbridge County, Va., and is reported from scheelite 

veins near Mina, Mineral County, Nev., but the report has not been 

confirmed. On Tin Creek, a tributary of Lost River, 100 miles 

northwest of Nome, Alaska, wolframite is found close to Cassiterite; 

in the Franklin Mountains, 15 miles north of El Paso, Tex., wolframite is found in small quantity in veins of Cassiterite.

At Kuils River, South Africa, there is an association of minerals 

apparently very much like that at Hill City.1

Wolframite and cassiterite are commonly associated in Cornwall, 

Saxony, Austria, Spain, Queensland, Tasmania, Malay Peninsula, 

Burma, Siam, and the Shan States..

A considerable part of the world's annual output of tungsten is 

produced as a by-product of tin mines.2 Not nearly so much scheelite 

as wolframite is found in tin ores, but perhaps the proportion is 

not much less than the proportion of scheelite in the total world's 

production of tungsten minerals.

 Chalcedony. Chalcedony is a form of quartz that does not break 

with the smooth, glassy fracture of common quartz, but that has a 

fracture resembling ground glass. By the eye alone no difference 

can be told between very fine grained quartz and chalcedony.

Quartz that appears to be chalcedonic is found in many parts of 

the veins of the Boulder area, in Colorado (PI. XXIV, 4), at Silverton, Colo., and at Atolia, Cal., but when examined microscopically it 

all proves to be merely fine-grained quartz. However, chalcedony 

.mixed with opal forms a Avhite coating over some of the ferberite 

crystals of the Boulder area.

1 Rumbold, W. R., The South African tin deposits: Am. Inst. Min. Eng. Trans., vol. 39, 

p. 783, 1909.

2 For titles and brief abstracts of books, papers, and items on the association of cassiterite and tungsten minerals see Hess, F. L. and Eva, Bibliography of the geology and 

mineralogy of tin: Smithsonian lust Pub. 1987, 408 pp., 1912,
52 TUNGSTEN MINERALS AND DEPOSITS.

Opal. Opal is a variety of quartz or silica that is combined with 

water. It is softer than quartz and breaks with a smooth, glassy 

fracture. The precious opal is made up of thin plates that refract 

or break up light so as to give " fire " effects, but most opal does not 

do this. Specimens sent by the Spanish Springs Mining Co. from 

Spanish Springs, at the south end of the Toquima Kange, 7 miles 

southeast of Manhattan, Nev., contain brownish-yellow opal in 

masses half an inch to three-quarters of an inch across. As already 

stated, opal mixed with chalcedony forms a thin coating on ferberite 

crystals from the Boulder tungsten field.

Quartz. Silica, silicon dioxide (Si02 ), is limpidly colorless, 

milky, yellowish, brown (" smoky "), or amethystine and is too hard 

to be scratched with a knife. Its specific gravity is 2.65. The streak 

is colorless or its color is like that of the quartz itself but fainter.

Quartz is the universal vein mineral. Nearly all waters that deposit vein materials deposit quartz with them, and it forms the 

larger part of most metalliferous veins. In tungsten veins the 

quartz is usually colorless or milky, but a vein near Loon Lake, 

Stevens County, Wash., carries some smoky quartz. In the veins of 

the tungsten area in the Boulder field much of the quartz resembles 

chalcedony and is of a greenish-gray color.

In veins that contain vugs quartz ordinarily forms projecting crystals. In some tungsten-bearing veins the quartz was deposited at 

the same time as the tungsten 'minerals; in others it was deposited 

without tungsten minerals; these were next la-id down and then 

another deposit of quartz; and in the Clark Mountains, CaL, this 

deposit was in turn succeeded by that of another tungsten mineral, 

scheelite. (See PI. XIII, A.)

Hematite. The iron oxide known as hematite (Fe2 03 ) is a rather 

common and frequently a puzzling constituent of tungsten ores. It 

is generally dark steel gray to iron black, but at some' places it has 

a reddish-brown tint, probably due to its alteration in part to limonite, the hydrous iron oxide. Its hardness ranges from 5.5 to 6.5 

from a little less to a little more than the hardness of a pocketknife. 

Its specific gravity ranges from 4.2 to 5.3 and is less than that of the 

wolframites (7 to 7.5). Hematite occurs in tungsten veins in two 

principal forms in scales or thin plates and in massive form. The 

plates range from microscopic size to an eighth of an inch or more 

across. The flat sides of most of the scales are bluish black. All 

hematites give a reddish-brown to cherry-red streak or powder, 

which distinguishes them from the wolframites, for which they are 

frequently mistaken. Specular hematite (specularite, hematite in 

scaly forms) occurs in parts of the ferberite veins of the Boulder 

tungsten field and greatly resembles fine-grained ferberite. 1 Specii See appendix.
U. S. GEOLOGICAL SURVEr

A. FERBER1TE WITH FINE-GRAINED QUARTZ HAVING THE APPEARANCE OF CHALCEDONY,

FROM CONGER MINE, NEDERLAND, COLD.

B. POLISHED SPECIMEN OF SCHEELITE (ABOVE) WITH A THICK CRUST (BELOW) OF CALICHE

(CALCIUM CARBONATE), FROM WICKARD MINE, NEAR ATOLIA, CAL.

Both natural size.
TUNGSTEN DEPOSITS. 53

mens sent from the Yucca district of Arizona are remarkably like 

some of the "peanut ores" of the Boulder area. Many specimens 

of specular hematite are sent to the Survey under the impression 

that they contain tungsten.

CARBONATES.

Calcite, dolomite, ankerite, and siderite. Carbonates are common 

in tungsten veins and grade into one another by stages so easy that 

it is impracticable to distinguish them except by chemical analyses. 

Calcite, lime carbonate (CaC03 ), is a mineral familiar to nearly 

all prospectors and miners as dog tooth spar when crystallized or as 

" lime " when it shows no outward crystal form. It is mistaken for 

scheelite only by the " tenderfoot" or by the beginner in prospecting. 

Its specific gravity is low, about 2.7; it is easily scratched with a 

knife (hardness, 3); and it may generally be easily cleft into parallelfaced six-sided shapes.

Siderite, iron carbonate (FeC03 ), is so similar to calcite that the 

molecules crystallize together as ferruginous calcite [(Ca,Fe)C03 ], 

which may contain a rather large proportion of iron, yet the 

mineral may be clear white, as it is in the gangue of the largest 

veins of scheelite at Atolia, Cal., or gray, as it is in other veins of the 

same region. It turns rusty when weathered. Veins at Hillgrove, 

New South Wales, have as outcrops a gossan or residue of iron 

oxide, probably due to the iron in the calcite.1

No dolomite, the calcium-magnesium carbonate [(Ca,Mg)C03 ], 

has been recognized by the writer in tungsten deposits but is reported to occur in them, and a number of analyses of scheelite show 

the presence of magnesium, which, however, may be contained in 

ankerite, the calcium-iron-magnesium carbonate [(Ca,Fe,Mg)COa ]. 

In the tungsten deposits at Atolia, Cal., quartz is deposited along 

cleavage cracks in the calcite, so that if the calcite is dissolved with 

acid a skeleton of quartz is left, which shows the form, direction, and 

extent of the cracks. The scheelite of the deposit has largely replaced calcite, and polished specimens show the silica skeleton of 

the calcite that originally occupied the space. (See PI. X, A.) 

Specimens from the Minerva district, near Shoshone, White Pine 

County, Nev., show the replacement of ferriferous calcite by scheelite, 

and Hill 2 reports the replacement of calcite by scheelite on the east 

side of the Ruby Range, 10 miles south-southwest of Ruby Valley 

post office, Elko County, Nev.

In weathered specimens calcite may be difficult to distinguish from 

scheelite by the eye alone, but in broken specimens the jagged sur1 Longbottom, W. A., Scheelite mining; Occurrence and treatment in New South Wales : 

Mln.'and Eng. Rev., vol. 3, p. 200, Sydney and Melbourne, 1911.

2 Hill. J. M., Notes on some mining districts in eastern Nevada: U. S. Geol. Survey 

Bull. 648, pp. 62-63, 1916.
54 TUNGSTEN7 MINERALS AND DEPOSITS.

face formed by the visible parts of the cleavage planes of the calcite 

and the cleavage lines that may be seen on any flat cleavage surface 

will at once show the difference, as will the poorer luster and lower 

specific gravity. The application of any acid, even strong hot 

vinegar, to calcite will at once make it throw off bubbles of carbon 

dioxide.

Owing to its low specific gravity calcite is readily separated from 

scheelite in panning or milling.

SILICATES.

Feldspars. Adularia, a potassium-aluminum silicate (K2O.A12O3. 

6Si02 ) is a variety of orthoclase feldspar which crystallizes in peculiar 

forms, many of the sections of which are rhombs. It is found in the 

ferberite veins of the Boulder tungsten field, but invariably in small 

quantity, and it is of little or no importance. Orthoclase and albite 

are reported from some foreign tungsten veins.

Beryl. Beryl, a silicate of aluminum and the rare metal glucinum 

(commonly known as beryllium) (3G10.Al2O3.6SiO2 ), generally 

forms in six-sided prisms and may be white, buff, yellow, pink, or 

green. The transparent emerald-green variety is the gem stone known 

as emerald, the bluish-green variety is that known as aquamarine. 

Beryl has a hardness of 7.5 to 8, a little greater than that of quartz, 

and a specific gravity of about 2.7, practically the same as that 

of quartz. Nearly opaque buff beryl is found in a tin-tungsten vein 

on Irish Creek, Rockbridge County, Va. It is not known to have 

been found in other veins of the United States, though it occurs in 

many tungsten-bearing pegmatites. Dunstan states that it is one of 

the common minerals in tungsten deposits in Queensland.1

Chlorite. Chlorite is a name for a group of mica-like minerals, 

most of which are green and can not readily be distinguished in the 

field. They occur usually in very small plates. Chlorite is found in 

a few tungsten-bearing veins but is not common in such veins in this 

country.

Muscovite. Muscovite is the ordinary white mica, a hydrous potassium-aluminum silicate (2H2O.K2O.3Al2O3 .6Si02 ). Muscovite that 

occurs in plates so small as to be nearly or quite microscopic is called 

sericite. In this form it is found in many quartz-tungsten veins, and 

in some, such as those near Hill City, S. Dak., the plates reach an 

eighth of an inch or more across. Its characteristics are well known; 

it has a glistening silvery appearance and is easily cleft into thin 

scales or leaves, which are flexible and elastic. It is easily scratched 

with the finger nail. Muscovite is the-form of mica that is used in 

stoves and lamps and is erroneously called " isinglass."

1 Dunstan, B., Wolfram in Queensland : Under Secretary for Mines Ann. Kept, for 1903, 

p. 151, 1904. Also, Queensland Government Min. Jour., vol. 6, p. 334, 1905.
TUNGSTEN DEPOSITS. 55

Lepidolite. Lepidolite is a lithium-bearing mica, in general, appearance much like muscovite, but it may be pink, red, lilac, lavender, 

or other colors. It is known in only one tungsten vein, that at Silvermine, Madison County, Mo.1 Lepidolite is considered an almost 

typical pegmatite mineral and is rarely found in veins.

Topaz. Topaz is a mineral containing aluminum, oxygen, fluorine, 

and silicon (AlF2 .AlSi04 ). It commonly occurs in nearly opaque 

or translucent masses, but may be limpidly colorless or transparently 

pale blue, pink, yellow, and other tints. It has a hardness of 8, so 

it will scratch quartz. It has a specific gravity of 3.4 to 3.65, a third 

greater than that of quartz.

It is found in fibrous masses an inch or more thick in the veins on 

Tin Creek, Lost River, 110 miles northwest of Nome, Alaska, and in 

microscopic crystals in specimens sent by John L. Gardiner from the 

Humbug district, Yavapai County, Ariz. It is common in tungstenbearing veins in Queensland 2 and in veins in New South Wales.3 

Yellow topaz is found in " considerable amount" in the wolframitebearing veins of TavOy.4 It is uncommon and of little importance 

in prospecting or mining in this country.

Tourmaline. Tourmaline is a complex silicate of boron and aluminum with fluorine, iron, magnesium, sodium, potassium, or lithium, 

and in some specimens with other elements. Most iron tourmaline is 

black and most magnesium tourmaline is brown; the tourmalines 

found in American tungsten veins are of these colors. Tourmaline 

normally occurs in six-sided prisms, generally slender. It has a hardness of 7 to 7.6, equal to or slightly higher than that of quartz.

Black tourmaline is found with wolframite in veins on the Black 

Metal claims, a mile northeast of Hill City, S. Dak., and on the 

Black Horse claims near Daisy, Stevens County, Wash. Brown 

tourmaline in mats of slender, silky crystals is found with wolframite 

in specimens sent by Peyer & Gallup from the Copper Mountain 

(Picuris) mining district near Rinconada, N; Mex. In thin sections 

the tourmaline shows a beautiful brownish-orange color. In a specimen sent by Wilson Jones from a vein cutting schist in sec. 6, T. 30 

S., R. 40 E., near Randsburg, Cal., tourmaline in microscopic crystals 

gives a black color to part of the calcite, which is so thoroughly impregnated with the tiny crystals that its color is changed. Under

1 Haworth, Erasmus, A contribution to the Archean geology of Missouri: Am. Geologist, 

vol. 1, pp.'294-295, 1888.

2 Macdonald, A. R., The Queensland mining industry ; Review of the year 1910; Wolframite, molybdenite, and bismuth : Queensland Government Min. Jour., vol. 12, p. 110, 

1911.

3 Came, J. E., The tungsten mining industry in New South Wales : New South Wales 

Geol. Survey Mineral Resources No. 15, pp. 43, 44, and 93, 1912.

4 Page, J. J. A.. Remarks on E. Maxwell-Lefroy's " Wolframite mining in the Tavoy 

district, Lower Burma " : Inst. Min. Met. Bull. 138, p. 47, 1916.
56 TUNGSTEN- MINERALS AND DEPOSITS.

the microscope the crystals appear faintly blue. A specimen from 

Bolivia shows tourmaline, and the mineral is common in many foreign 

tungsten deposits.1

PHOSPHATES.

Apatite. Apatite is of two general varieties, one containing fluorine, a calcium fluoride and phosphate, CaF.Ca4 (P04 ) 3 , and one containing chlorine, a calcium chloride and phosphate, CaCl.Ca4 (P04 ) 3 . 

Both varieties form six-sided crystals, which may be white or colored 

green, yellow, gray, flesh-red, red, or brown. Apatite has a hardness 

of 5, so is harder than fluorite or calcite but is easily scratched by 

a knife. Its specific gravity is about 3.2.

Small light-green masses of apatite one-eighth of an inch thick are 

found in the veins at Hill City, S. Dak. Small brownish-yellow 

prisms one thirty-second of an inch thick and white irregular masses 

an inch thick are found in and with scheelite in the Clifton district, 

Deep Creek Mountains, Tooele County, Utah. It is reported to 

occur in some deposits in western Nevada, but the Survey has not 

verified the reports. Apatite is an undesirable mineral in a tungsten 

ore, for it carries phosphorus, and phosphorus in any but the most 

minute quantities is ruinous to steel. It can be largely or wholly 

eliminated, however, by careful milling. Ordinarily 0.05 per cent 

of phosphorus is the uppermost allowable limit.

Hamlinite (?). Practically all the ferberite ores of the Boulder 

tungsten field carry traces of phosphorus, which apparently come 

from a mineral found particularly in the highly siliceous ores but 

only in microscopic particles. The optical properties of these particles seem to correspond to those of hamlinite, a hydrous strontiumaluminum phosphate (2Sr0.3Al2 03 .2P03 .2P2 05 .7H2 0). Material 

sufficiently pure for a good quantitative analysis could not be obtained, but qualitative determinations of that in hand showed that 

it contained the elements of hamlinite, which is probably the phosphorus-bearing mineral of the Boulder field. It has not been found 

in other tungsten ores. It has about the same specific gravity as 

apatite (3.2) and is easily removed from the ores by fine crushing 

and good milling. Because of its presence rich hand-picked ores arc 

not so desirable as milled concentrates of the same richness, for it will 

have been largely removed with the other gangue minerals in the 

milling process.

1 Bleeck, G. W. A., On some occurrences of wolframite lodes and deposits In the Tavoy 

district of Lower Burma: India Geol. Survey Rec., vol. 43, p. 69, 1913.

Dunstan, B., Wolfram in Queensland: Queensland Government Min. Jour., vol. 6, p. 

334, 1905.

Granigg, B., and Koritschoner, J. H., Die turmalinfuhrende Rupferkies-Scheelitlagerstatte am Monte Mulatto bei Predazzo (Siidtirol) : Zeitschr. prakt. Geologic, Jahrg. 21, 

p. 484, 1913.

Faribault, E. R., Structure of the tungsten deposits of Moose River, Nova Scotia: Nova 

Scotia Min. Soc. Jour., vol. 15, p. 62, 1910.

Bronckart, F., Le wolfram en Portugal: Soc. ge"ol. Belgique Annales 1908, p. B-182, 

1909.
TUNGSTEN DEPOSITS. 57

TriplUe. Triplite (3MnO.P2 0B .MnF2 ), a manganese phosphate 

and fluoride, occurs as a flesh-pink mineral in small quantity 

with hiibnerite in the Began district, Nev.,1 and a little has been 

noted with hiibnerite in specimens from a deposit 8 or 10 miles north 

of Goffs, Cal. Its specific gravity is low, 3.T9, about equal to that of 

quartz, so that it may be readily separated from tungsten minerals. 

Its hardness is 4 to 4.5.

MINERALS CONTAINING COLTTMBIUM AND TANTALUM.

Columbium and tantalum minerals as such are unknown in tungsten-bearing veins in this country. Bleeck 2 states that columbite 

is found in all the wolframite-bearing veins in the Tavoy district, 

, Burma, but no references to its occurrence in tungsten veins of 

other countries are known. Columbium and tantalum oxides are 

found in some American wolframites in quantities which reach more 

than 2 per cent, but the form in which the elements occur is unknown.

In this country columbium and tantalum oxides have been reported 

as follows:

Columbium, and tantalum oxides in tungsten minerals.

Per cent

Hiibnerite from Ouray County, Colo., Cb200 (?)_-_____ 0.05 

Hiibnerite from White Oaks, N. Mex., (Cb,Ta) 2 00 (?)___ Trace. 

Wolframite from Irish Creek, Va., (Cb,Ta) 2Oc , etc______ .96 

Wolframite from Pioche, Nev., (Cb,Ta) 2OB___________ .82 

Wolframite from Cave Creek, Ariz., (Cb,Ta) 20B ________ 2.20 

Ferberite from Boulder .County, Colo____________ __ ( 8 )

Tantalum is reported to have been found in the wolframite of the 

Tip Top and Humbug districts of Arizona. The Survey has made 

no determinations of tantalum in ores from these districts, but as 

the ferberite from Cave Creek, Ariz., is rich in tantalum and columbium, the discovery of these metals in wolframites from other districts of the State would not be particularly surprising.

These metals have been reported to occur in wolframite or ferberite 

obtained from nearly a dozen places outside of the United States, in 

amounts ranging from traces to 1.22 per cent. From Lake Couchiching, Ontario, there is doubtfully reported 1.95 per cent of columbium pentoxide (Cb2 0B ).4

The slimes from the tin-dressing plants around Camborne, Cornwall, flow into Ked River and by it are concentrated along its banks

1 Hess, P. L., and Hunt, W. F., Triplite from eastern Nevada: Am. Jour. Sci., 4th ser., 

vol. 36, pp. 51-54, 1913.

3 Bleeck, G. W. A., On some occurrences of wolframite lodes and deposits in the Tavoy 

district of Lower Burma: India Geol. Survey Rec., vol. 43, p. 69, 1913.

8 Columbium pentoxide (Cb20s) present in small quantity.

* See Hess, F. L., and Schaller, W. T., Colorado ferberite and the wolframite series: 

U. S. Geol. Survey Bull. 583, pp. 18, 24-35, 1914, for analyses of wolframites. '
58 TUNGSTEN MINERALS AND DEPOSITS.

and by the sea at Gwithian. Holloway 1 estimates that more than 100 

tons of tungsten annually go to waste in these slimes. They contain 

also tantalum, columbium, uranium, vanadium, and molybdenum.'

MINEKALS FOUND IN TUNGSTEN-BEARING PEGMATITES.

The minerals of the pegmatites are ordinarily those of the parent 

rock mass. The commonest minerals are quartz, feldspar, and muscovite mica, and in the United States tungsten occurs in dikes composed of these minerals, especially "in dikes that contain quantities of 

quartz so large that the dikes approach quartz veins in composition. 

Some pegmatites, however, carry a great variety of minerals, many of 

them rare. In pegmatites that contain a multiplicity of minerals, 

tungsten, like tin, seems to occur only in small quantity. In New 

South Wales many large masses of wolframite, one weighing 300 

pounds, have been found in pegmatites that contain many other 

minerals, but the percentage of tungsten in the dikes as a whole seems 

to be low, and they are of doubtful value as a source of tungsten.2 

Considerable masses of wolframite have been taken from pegmatite of 

simpler composition in the Mount Carbine tungsten district, Queensland.3 The following list of minerals found in the Etta dike, 1| 

miles south of Keystone, S. Dak., shows how many minerals may be 

contained in a complex pegmatite.4 The minerals indicated by 

italics occur in large quantity.

.Albite. Columbite. Melanite (anclradite). Sphene.

Andalusite. Corundum. Microcline. Spinel.

Apatite. Epidote. Molybdenite. Spodumene.

Arsenopyrite. Graphite. Monazite. Staunite.

Autunite. Griphite. Muscovite. Struverite.

Barite. Grossularite.. Orthoclase. Tourmaline.

Beryl. Heterosite. Petalite. Triphylite.

Biotite. Ilmenite. Quarts. Triplite.

Bismuth. Lepidolite. Rutile. Wolframite.

Cassiterite. Lithiophilite. Scheelite. Zircon.,

Chalcocite. Lollingite. Scorodite.

Wolframite is the tungsten mineral most commonly found in pegmatites. In many dikes it is accompanied by small quantities of 

scheelite, and in a few pegmatites scheelite is the only tungsten mineral present. Like cassiterite (tin oxide), the tungsten minerals

seem not to have crystallized in quantify in such rocks, even where

_ .

1 Holloway, G. T., The relation between the mineral and the chemical industries: Soc. 

Chem. Ind. London Jour., vol. 29, p. 59, 1910.

"Conder, Hartwell, The wolfram deposits of New England [New South Wales] : Min. 

Jour., vol. 78, pp. 170-171, 1905.

8 Ball, L. C., The wolfram mines of Mount Carbine, North Queensland : Queensland 

Geol. Survey Pub. 251, p. 34, 1915.

4 O'Harra, C. C., Mineral resources of South Dakota: South Dakota Geol. Survey Bull. 

3, p. 64, 1902. This list has been somewhat altered in the light of more recent investigations.
TUNQSTEK DEPOSITS. 59

they were in the solutions that accompanied the injected pegmatite, 

until after most of the mica, feldspar, and other minerals crystallized. No large production of tungsten has yet been made, at least 

in this country, from pegmatites, the term being strictly interpreted.

OUTCROPS OF TUNGSTEN VEINS.

The outcrops of tungsten veins resemble those of other veins, and 

their character depends on the geologic history of the country, the 

minerals of the veins, the composition of the country rock, and the 

climate. In those parts of the country over which glaciers have 

moved in comparatively recent geologic time the surface rock is generally planed down, so that though the veins may be harder or softer 

than the country rock they are not likely to rise above or to be depressed below the general level, for weathering may not have gone far 

enough to show much difference between veins and country rock. In 

unglaciated country the form of the outcrops of veins depends on 

a variety of .factors.

In general, tungsten veins (among which are not classed pegmatite 

dikes or contact-metamorphic deposits) fall into three classes: 

Quartz veins, carbonate veins, and thin veins carrying comparatively 

little gangue.

Quartz veins of course resist weathering better than most rocks 

and stand somewhat above the country rock unless they have been 

so much shattered that water collects in cracks and by freezing 

disintegrates them rapidly, or unless they originally contained many 

comparatively soluble or easily altered minerals that have been removed by weathering, which thus produces cavities in which water 

freezes and breaks down the veins. Thus the barren quartz may 

form a prominent outcrop, whereas the ore shoots may weather down 

to or below the general surface.

Carbonate veins that is, veins composed largely of carbonate minerals, calcite or the closely related calcium-magnesium-iron carbonates disintegrate under weathering rather easily and are not 

likely to protrude above the country rock unless they contain considerable quartz. They are likely to be somewhat lower than the 

general level except where the country rock is limestone. None 

of the veins at Atolia, Cal., project above the ground because nearly 

the whole area is covered with desert debris, so that outcrops are 

difficult to find. Thin veins, like those of the Boulder field, are too 

weak to withstand much pressure from mud and debris and therefore 

conform to the general level.

Whether' a vein projects above the surface or not depends almost 

as largely on the country rock as on the vein.

In general granitoid rocks, such as granite, granodiorite, and diorite, waste under weathering slowly but faster than quartz. Some
60 TUNGSTEN MINEBALS AND DEPOSITS.

such rocks, however, weather rapidly, especially where they have 

been altered by vein-forming solutions. Hiibnerite veins are reported 

' to stand as much as 10 feet above the surrounding granitoid rock at 

Camp Signal, 8 miles north of Goffs, Cal.1 Schists usually weather 

faster and dolomite and limestone much faster than quartz veins. 

Thus at Patterson, Lemhi County, Idaho, quartz veins carrying hubnerite project as much as 30 feet above the schist surface on one side, 

though the schist on the other side of the vein is weathered away to 

a much less depth.2 Some of the veins in the Snake Kange, White 

Pine County, Nev., are p reported to stand a number of feet above the 

surface, and those at Dragoon, Ariz., stand somewhat above the 

surface. Some of the wolframite-bearing pegmatite dikes that.cut 

the schists near Hill City, S. Dak., stand 12 or 15 feet above the 

country rock.

There is a great difference in the way in which the different tungsten minerals stand weathering, and consequently in the quantity of 

them which may be left in the outcrops. The ferberite of the Boulder 

tungsten area remains unaltered, so the veins are generally about 

the same at the surface as at depth, and the pieces that have broken 

off the weathered vein remain in the soil and have formed valuable 

placers. Ferberite, near Hill City, S. Dak., weathers to a mass of 

iron oxide (PL XXIII, J.), which may yet show a sheen along the 

original cleavage planes. Wolframite in the Kootenay Belle mine, 

near Salmo, British Columbia, in a cool, moist climate, weathers and 

leaves behind a deposit of tungstite.3 (See PI. XV, B.} No deposit 

so large is known in this'Country. In the Malay Peninsula and in 

Siam, where the climate is hot and wet, wolframite is found in placers 

with cassiterite. At Dragoon, Ariz., Round Mountain and Spanish 

Springs, Nev., and other places commercially valuable hiibnerite 

placers have been formed by the weathering of veins. At Silverton, 

Colo., hiibnerite is weathered from the quartz gangue, which contains 

the cavities it once occupied. In the Snake Eange, Nev., scheelite 

weathers from the outcrops, leaving cavities in the quartz, though it 

also ±;orms float.4 Near Loon Lake, Wash., where the climate is 

comparable to that of Silverton, hiibnerite forms float. Sulphides 

occur with the tungsten minerals both in the Snake Eange and at 

Loon Lake. In both the wet country around Nome and the desert 

around Atolia and Kandsburg scheelite forms placers.

Why tungsten minerals should decay in one place and not in 

another is not invariably clear. The difference does not seem to be due

1 Main, J. F., personal communication.

2 Lind, J. G., Geology and tungsten deposits of the Patterson Creek district, Idaho, 

p. 8, 1912. (Private report.)

3 Walker, T. L., Report on the tungsten ores of Canada : Canada Dept. Mines, Mines 

Branch, Pub. 25, p. 37, 1909.

4 MacVichie, Duncan, personal communication.
TUNGSTEN DEPOSITS. 61

to differences in climate, but probably decay is generally caused by 

the breaking down of accompanying sulphides, which form sulphuric 

acid that attacks the tungsten minerals. Differences in the physical 

structure of the minerals and the presence of impurities in the minerals may also cause some differences in weathering. The principal 

sulphides from which sulphuric acid may be formed by weathering 

are pyrite and chalcopyrite. Both form iron oxides, which stain 

other minerals and rocks, greatly disguising them. Copper carbonates also in some places cover scheelite and infiltrate along cracks 

in it, making it less easy to recognize. Manganese oxides weathered 

from the country rocks or even from hubnerite or triplite in a vein 

give a smutty coating to quartz and other vein minerals, which 

may make their identification more difficult.

DOWNWARD EXTENT OF TUNGSTEN VEINS.

A question in the mind of nearly every owner or operator of a 

tungsten mine or locator of a tungsten prospect is, " To what depth 

does the tungsten reach ?" and the value of the property depends 

in large measure on the answer. Few tungsten mines have been 

worked to great depths, but the East Pool & Agar (Ltd.) mine 

at Cam Brea, Cornwall, England, has been worked below the 300- 

fathom (1,800-foot) level on the Great Lode. At these mines wolframite, cassiterite, arsenopyrite, and chalcopyrite are saved.. On the 

Middle Lode work is being prosecuted at the 240-fathom (1,440-foot) 

level.1 In the South Crofty property, which adjoins the East Pool 

and on which the same lodes are worked,

The distribution of the wolfram is irregular; it is most abundant in the 

middle levels and can not be depended on below 245 fathoms (1,470 feet). The 

best lode is not payable below 205 fathoms (1,230 feet), at which level the 

average yield of tin and wolfram together is 23 pounds a ton [2,240 pounds]. 

A rise from this level in the western part of the mine showed as much as 40 

pounds a'ton. The average content of the ore crushed during 1914 was as 

follows (in pounds per ton) : Tin, 20.66; wolfram, 3.63; arsenic, 22.67; copper 

and sundry products, 26.96; giving a total value at the average prices for the 

year of £1 2s. 9.72d. per ton of ore crushed.2

In the eastern part of the South Crofty property, known as " Bickford's," at the 310-fathom (1,860-foot) level the lode is apparently as 

rich as the average of other parts of the mine.

Of the scheelite deposits at Hillgrove, New South Wales, J. E. 

Carne says: 3

Whilst the individual lenses and thin veins of ore are extremely capricious in 

occurrence, there is no reason to doubt their persistence at great depths. In

1 Dewey, Henry, and others, Tungsten and manganese ores: Great Britain Geol. Survey 

Mem., Special reports on the mineral resources of Great Britain, vol. 1, pp. 20-21, 1915.

a Idem, p. 17.

8 Carne, J. E., The tungsten mining industry in New South Wales: New South Wales 

Geol. Survey Mineral Resources No. 15, p. 49, 1915.
62 ' TUNGSTEN MINERALS AND DEPOSITS.

fact, nature has already demonstrated this by exposing scheelite deposits in the 

sides and bed of Bakers Creek Gorge to a depth of 1,400 to 1,600 feet, or 

more. * * *

This view is strengthened by the wonderful persistence of the extremely thin 

Smiths Gold Reef, in Bakers Creek Gorge, which outcrops about 1,500 feet 

below the level of Hillgrove, and which has been followed down in the Bakers 

Creek and Proprietary mines for 2,000 feet and still persists strongly.

Gray and Winters,1 after studying the wolframite and molybdenite 

deposits in aplites at Yenberrie, Northern Territory, Australia, conclude that:

The uniformity of the aplites in a rapidly varying granite mass indicates that 

the aplite is not a separation from the surface granite but from some underlying source; and the fact that their direction is that of the main and regional 

intrusions points to a reservoir controlled by regional rather than local forces.

These conditions decidedly point to a considerable depth as the source of the 

aplite and quartz, and give to the ore deposits promise of a considerable persistence in depth.

At White Oaks, N. Mex., hiibnerite has been found at a depth of 

1.350 feet. In the Boulder field, Colo., no ferberite ores have been 

found at a depth greater than 900 feet, but the question of depth can 

not be considered as settled for the field. At the East Union mine, 

Atolia, Cal., the greatest quantity of ore was found on the eighth 

level (about 800 feet deep along the vein and about 400 feet below 

the surface vertically) and the mine still yields good ore at a depth 

of 1,000 feet along the vein, which is equivalent to a vertical depth 

of about 510 feet.

A study of the accompanying minerals in tungsten-bearing veins 

gives some basis for estimating the depth to which tungsten deposits 

may have extended below the surface at the time the deposits were 

formed. Tourmaline, topaz, cassiterite, beryl, arsenopyrite, and 

apatite are among the minerals that are usually considered characteristic of deposits that have been formed at considerable depths 

below the surface, and all are found in* some tungsten deposits. Pegmatites, it is thought, were extruded from great depths, and the occurrence of tungsten minerals in pegmatites has been noted at several 

places in this bulletin (see pp. 58-59), as has the fact that many veins 

that carry tungsten minerals are evidently closely related to pegmatites in origin.

Lindgren, in writing of the ferberite veins of Boulder County, 

Colo., puts them in a class wholly different from veins closely related 

to the pegmatites. He says: 2

Although the filling of these veins is very different from that of the telluride 

veins at Eldora, there is unquestionably a strong resemblance between them

1 Gray, G. J., and Winters, R. J., Report on Yenberrie wolfram and molybdenite field: 

Northern Territory of Australia Bull. 15A, p. 3, 1916.

3 Lindgren, Waldemar, Some gold and tungsten deposits of Boulder County, Colo,: Econ, 

Geology, vol. 2, p. 462, 1907.
TUNGSTEN DEPOSITS. 63

as far as the structure of the vein and serlcitization of the country rock are 

concerned, and this leads to the belief that the tungsten veins are also a product 

of comparatively recent thermal activity, and that they are deposited at only 

a moderate depth below the original surface.

Wolframite is found in pegmatite veins, in company with cassiterite and 

other minerals of rarer kind. More commonly it is found in quartz-filled veins 

similar to the ordinary gold quartz deposits of California. The tungsten deposits of Boulder County differ from both of these types.

Some ferberite veins, however, cut through or lie near pegmatite 

dikes, but the connection between the two may be accidental, and the 

veins are, at least in part, undoubtedly later.1

Different tungsten deposits may have been formed at different 

depths, but most tungsten deposits doubtless extend to depths as 

great as those reached by deposits containing other metals. Many 

tungsten veins, like veins carrying deposits of gold, silver, tin, copper, and other metals, will give out at shallow depths, and only the 

exceptional mine may be expected to yield ore of good quality in 

commercially valuable quantities to great depths. Probably not one 

in five hundred gold-bearing veins carries commercially valuable ore 

below a depth of 100 feet. Possibly tungsten veins may carry ore at 

depths greater than those reached by workable gold veins, but this 

possibility has not yet been demonstrated by actual developments.

In a general way the depths that are reached by gold-bearing 

veins are indicated by the length of their outcrops, but tungsten 

deposits whose outcrops are comparatively small seem to reach relatively greater depths, especially those that have pegmatitic characteristics. In Queensland pipes only a few feet in diameter that 

carry tungsten, molybdenum, and bismuth minerals have been 

worked . to considerable depths.2 Nothing like these tungstenmolybdenum-bismuth bearing pipes, however, is known in the 

United States.

In writing of the ferberite deposits of Boulder County, Colo., 

George 3 says:

The ore is distributed along the'veins in bunches and pockets or rarely 

shoots, and up to the present nothing has occurred to suggest that the downward distribution is less regular than the lateral. In fact, a considerable 

number of the best ore bodies have had greater vertical than lateral dimensions.

This statement applies also to the scheelite deposits at Atolia, Cal.

UNEVEN DISTRIBUTION OF TUNGSTEN IN THE VEINS.

It has often been said that tungsten veins are more erratic than 

veins carrying other metals, and that the distribution of the ore in 

them is more irregular, so that the deposits can not be depended

1 See appendix.

- Cameron, W. E., Wolfram and molybdenite mining in Queensland : Queensland Geol. 

Survey Kept. 188, p. 13, 1904. Anonymous, Wolfram mining in North Queensland : Australian Min. Standard, vol. 45, p. 614, 1914.

3 George, R. D., The main tungsten area of Boulder County, Colo.: Colorado Geol. Survey First Rept, 1908, p. 85, 1909.
64 -TUNGSTEN MINERALS AND DEPOSITS.

upon as well as deposits of other metals, but of this statement there is 

at present no proof. , Most vein deposits carry their valuable minerals 

in shoots, and the erratic occurrence of the constituents of pegmatites 

is well known.. The history of most gold, tin, silver, or other mines 

working on veins, except possibly those working in well-defined zones 

of reconcentrated ores, has been a history of the working out of one 

ore body after another. In most of the larger mines exploratory 

work is pushed along while the known ore bodies are being extracted. 

The precious-metal mines in which the ore bodies are very constant, 

such as those of the Kand, in the Transvaal, are not vein deposits in 

the ordinary sense of that term; they approach bedded deposits, in 

form at least, and so are not to be compared with vein deposits. The 

mine map that does not show a constant change in the metallic content of the veins is the record of a very exceptional mine, and many 

tungsten-bearing veins are at least as even in content as the average 

metal-bearing vein of other kinds.

WILL TUNGSTEN DEPOSITS GROW RICHER WITH DEPTH?

There is a widespread belief that most veins grow richer with depth 

and this fallacious belief has led to the expenditure of a great deal 

of money, labor, and time on worthless veins, and the constant repetition of this specious statement by many mistaken and some swindling 

promoters has encouraged the investment of money by the unknowing 

in the schemes.

A few valuable minerals, especially- the sulphides of silver and 

copper, are leached by ground waters, carried downward, and redeposited at or below the level of the ground water, and by this 

process the veins are impoverished above and enriched below. Below the enriched zone the veins carry their normal content of minerals, which may be too low to be commercially valuable, although 

the enriched portion may have been a bonanza. It has often been remarked that the same processes may have operated on tungsten ores, 

and Surr* thought that this was possible.

Tungsten minerals decay from the outcrops of veins, in some places 

leaving behind small quantities of tungstite and ferritungstite. In 

other places the wolframites leave behind iron oxide. (See Pis. XV, 

Z?, and XXIII, A.) At Cave Creek, Ariz., cuprotungstite seems to 

have been formed by the decomposition of copper sulphides and 

ferberite and has spread through the rocks. At Hill City, S. Dak., 

the writer collected a specimen in which a little scheelite seemed to 

have been deposited in a crack that had been formed since, the vein 

had been mineralized, and above this crack ferberite (wolframite?) 

had been weathered out.

1 Surr, Gordon, Tungsten deposits and surface enrichment: Min. World, vol. 30, p 19, 

.1909. °
TUNGSTEN DEPOSITS. 65

Stolzite and raspite are apparently secondary minerals, but their 

origin is obscure, and, like cuprotungstite, they have never been 

found in large quantity.

It therefore seems possible that there may be some downward 

enrichment of veins carrying cuprotungstite, scheelite, stolzite, and 

raspite, but no corresponding redeposition of the wolframites has, to 

the knowledge of the writer, ever been noted.

No enrichment of ferberite, hiibnerite, or wolframite is believed to 

be possible, though some enrichment of scheelite may occur.

Chase 1 expresses the same view of the ferberite veins in the 

Boulder area, as follows:

My observation goes to show that any ordinary depth is going to cut .little 

figure with the ore occurrences. They are neither going to be better nor worse 

in depth. In other words, there is no evidence that I can see of any secondary 

enrichment or any different arrangement of the ore minerals after their 

original deposition. Many gold mines show an unusual high value on this 

account for the first 100 feet or so, and everybody knows there would be no 

commercial ore bodies in the " porphyry coppers " Avere it not for the secondary 

enrichment extending down a few hundred feet; they will all meet the lean 

primary ore at some depth. But I believe nothing of this kind has occurred

* with the tungsten, which exists as first deposited. The fact that the solutions 

came from great depths proves nothing, for I presume all ore bodies had their 

ultimate source in great depths. But what can be assumed is that the present 

manner of occurrence of the tungsten ore within 100 feet of the surface may be 

counted on for a repetition downward for 1,000 feet at least. The ore is and 

will be erratic. One day the face looks fine and to-morrow it gives one the 

blues.

/ WHERE TO PROSPECT FOR TUNGSTEN.

> As has been stated, tungsten is invariably associated with granitoid 

rocks, but tungsten-bearing veins may, and many do, cut through 

sedimentary beds, suchVs sandstones (including quartzite, which is 

only a strongly cemented form of sandstone), limestones, schists, 

slates, and the varieties of -these rocks. Some veins have also been 

found in tuffs (hardened beds of small volcanic fragments) and 

lavas overlying granite. Areas of any of these rocks close to granitoid outcrops are therefore those in which prospecting may meet 

with success.

Areas of dark igneous rocks, including serpentine, are unpromising, as are all the lavas, except such as may lie near granitoid rocks. 

No tungsten deposits are known to have been found in the very dark

* (basic) granitoid rocks, but it is not possible to say how far this fact 

may be used for generalization.

In most places the tungsten minerals set free by the weathering 

and erosion of the country rocks and the consequent exposure and 

breaking down of the veins form placers, many of them of consider1 Chase, E. E., An engineer's observations on the tungsten belt: Mih. American, vol. 73,

* p. 4, 1916.

47154° Bull. 652 17 5
66 TUNGSTEN MINERALS AND DEPOSITS.

able extent, such as those of Queensland, Burma (Tavoy), and the 

smaller ones at Round Mountain and Spanish Springs, Nev. Such 

placers, of course, should ordinarily be looked for in stream beds, 

arroyos, or older accumulations of gravel. In places tungsten minerals may be traced by panning from the streams or gulch bottoms 

through the dirt of the hillsides to the vein from which they came.

' K. / , I ' - *- \: A'U,/ ,-«v.v

'-" /,. Granite* * t . *

v/^,/.'/ v ^V,,

- "'/. 1 ,* ",'' "'V

 -;, ,^; *t 'A*

FIGURE 3.' Relation of tungsten veins to country rocks. Dotted areas along veins represent residual placers and along creeks stream placers. Contact-metamorphlc deposits 

are represented as metamorphosed limestone.

This is the old familiar method of the "pocket hunter" and has 

been successfully used at many places in tungsten prospecting. 

Figure 3 shows the relation of rocks, tungsten veins, and placers.

FIELD TESTS FOB TUNGSTEN MINERALS.

GENERAL INSTRUCTIONS.

The tests given below are not new, but are easy and definite. They 

are given for the use of the man in the field, where conveniences may 

be few and new supplies may be far away, rather than for-the man 

with a laboratory at hand. The writer has made these tests many 

times under conditions similar to those in the field and with materials that may be obtained at a minimum of expense and effort and 

may be carried in the field.

Simple acid test. A piece of the mineral to be tested, half the size 

of a pea, should first be finely pulverized and then digested with
FIELD TESTS FOE TUNGSTEN MINERALS. 67

hydrochloric (muriatic) acid. This test may be made in any receptacle that is not attacked by the acid a tumbler, bottle, teacup, 

or test tube, but the liquid should be in as compact a bulk as possible, 

so that a test tube is best. If the mineral is scheelite the digestion 

will need to be carried on only a few minutes, but wolframite, hiibnerite, or ferberitie should be boiled for 10 to 30 minutes or be heated 

to a lower temperature for a longer time. If the specimen tested contains tungsten minerals a yellow powder, tungsten trioxide (W03 ), 

will be produced, though the color may be masked by iron or other 

impurities. On the addition of metallic zinc the solution will turn 

indigo blue if sufficient tungsten trioxide has been formed. The 

depth of the color, and even the color itself, will depend largely on 

the extent of the digestion and the quantity of tungsten in the specimen tested. If only a little tungsten trioxide has been formed the

blue will be light, or even indistinguishable, and will be followed by 

violet and later by brown. It may even happen that no color is 

shown, but the powder itself will turn blue. If a considerable quantity of the trioxide has been formed the blue of the solution will be 

very deep and the violet will probably not appear, a muddy brown 

color succeeding the blue more or less quickly.

The fusion test. For a test of scheelite the use of acid alone is 

very satisfactory, but for the wolframites it does not serve so well, 

because they are not rapidly attacked by hydrochloric acid. A fusion 

test is simple and in general may be performed in less time than a 

test that requires boiling and digesting with acid alone, and the 

results are more positive.

The test consists in powdering a piece of the mineral (a piece onefourth the size of a grain of wheat is large enough), fusing it in a 

soda bead, digesting the bead in hydrochloric acid, and adding zinc 

to the acid solution, by which the characteristic blue color is obtained.

To make the bead, a platinum or iron wire is bent into a loop about 

one-eighth of an inch across, moistened to make the soda adhere, and 

dipped into sodium carbonate or sodium bicarbonate (ordinary bicarbonate, the baking soda of the kitchen, is as good as any), then held 

in a flame for two or three minutes to sinter slightly, and is then 

fused with a blowpipe flame. It is much easier to fuse the soda after 

it is sintered, for it is then not so liable to be blown from the loop 

by the flame of the blowpipe.

When the bead is fused it is dipped into the powdered tungsten 

mineral and again fused before the blowpipe.

After thorough fusion the bead is plunged into a mixture composed 

of half hydrochloric acid and half water. This mixture is heated 

over the flame until the bead is dissolved. If tungsten is present the 

bead, as it dissolves, usually takes a bright-yellow color from the 

tungsten trioxide formed. After the bead is dissolved zinc is added 

and if tungsten is present an indigo-blue color appears.
68 TUNGSTEN MINERALS AND DEPOSITS. 

NECESSARY MATERIALS.

Wire. Platinum is preferable for 'the wire because it is not attacked by single acids. However, it is very expensive, costing from two 

to more than five times as much as gold, and it is attacked by sulphur 

and alloys easily with some of the metals. Iron wire is a good 

substitute, and its cost is negligible. A piece of wire from a 

broom handle will do well, though finer, softer wire is preferable on 

account of the greater ease with which it can be heated and worked. 

Lengths of 5 or 6 inches, which may be put in a test tube and easily 

taken out without inverting the tube, are convenient. Copper wire 

may be used, but it conducts heat so rapidly that it adds greatly to 

the difficulty of fusion.

Flame. A candle furnishes an easily usable flame, is easily carried, is in stock at every metal mine, and can be purchased at almost 

uny store. A small kerosene lamp may be used, and paraffin or 

alcohol lamps are better than either, but are more troublesome to 

carry and for the alcohol lamp a special supply of fuel is necessary.

Blowpipe. The simple brass blowpipe is sufficient and is cheap. 

The hole in the tip should be small and the pipe should be about 10 

inches long in a direct line from the tip to the mouth. Some blowpipes have a slip joint in the middle and can be taken apart and more 

easily carried.

Test tubes. Test tubes 4 inches long and half an inch in diameter 

are of convenient size. The^y are inexpensive and take up little room. 

Six such tubes and six smaller tubes that nest inside of them make a 

good supply, weigh but little, "and are of small bulk. It is much 

easier to make a test in one of these tubes than in other receptacles, 

because of the compact bulk of the liquid and because a minimum 

quantity may be used.

Acid. Concentrated hydrochloric acid, preferably chemically 

pure, should be used, as more can be carried in the same bulk than of 

the dilute acid, and it can be diluted as needed. A rubber-stoppered 

bottle is best for carrying it, as glass-stoppered bottles that will not 

leak are difficult to get and corks are rapidly destroyed by the acid. 

Do not use too much acid. Ordinarily, half an inch in a test tube is 

more than1 sufficient, and to this quantity about as much water should 

be added.

Zinc. Zinc is used to generate hydrogen, which is set free from 

the hydrochloric acid when it attacks the zinc. The hydrogen then 

takes oxygen from the yellow tungsten trioxide, leaving the blue 

oxide. Almost any substance which sets hydrogen free may be used 

instead of zinc, but zinc is the best, for it is easy to obtain, acts more 

rapidly than other easily obtained metals, and is cheap. Tin, solder 

(an alloy of tin and lead), or sheet tin may be used as substitutes. 

Zinc may be obtained as shavings, shot, granules, sheets, or sticks.
U. 8. GEOLOGICAL SURVEY 

MATERIALS NECESSARY FOR TESTING TUNGSTEN 

From left to right: Blowpipe, candle (above), test tube, iron wires (one shows soda bead), 
PEECENTAGE OF TUNGSTEN IN OEES. 69

Granulated and shot zinc are the handiest. Granulated zinc may be 

made by melting, cooling almost to the solidifying point, and then 

pouring into some vessel in which it may be shaken sharply while 

it is hardening. Solder in the form of wire may be bought from any 

electrical supply firm and makes a good, easily carried substitute. A 

piece from a tin can works fairly well and may be made to do when 

better material is unavailable.

The materials necessary for the tests that have been described are 

shown in Plate XXV.

APPROXIMATE DETERMINATION OF PERCENTAGE OF 

TUNGSTEN IN ORES.

The miner may not be able to make chemical determinations of the 

percentage of tungsten or tungsten trioxide in his ore, because he 

lacks both the laboratory appliances and the technical knowledge and 

skill, but under some conditions he can make rough tests by taking 

the specific gravity of the ore, especially if the ore contains no other 

heavy metals and if the gangue is of nearly the same specific 

gravity in all parts of the deposit. A rough method used in the 

Mount Carbine district, Queensland, for estimating the richness of 

the ore mined is described by Lionel C. Ball: 1

The "gougers" gage of specific gravity is the 1-pound tea tin, which is 4| 

inches cube, and the greater the weight of a tin full the higher grade the wolfram is considered, 14 pounds being the maximum. Some of the Carbine wolfram (lolanthe) is said to weigh only 10 pounds to the tin, but the Little Nell 

runs 12 pounds. It has also been noticed that the coarser the grain of the 

concentrate the higher the specific gravity, there being a difference of one-half 

to 1 pound per tin in favor of the grains one-half inch in diameter as against 

fines. Further, Mr. West assures me that the wolfram from the deeper ground 

is certainly of greater specific gravity than that from the surface. These facts 

are probably to be accounted for by the perfect cleavage of the mineral resulting 

in open partings during weathering or crushing.

A somewhat better method has been used by A. D. Cox at the 

Union Hill mine, Grass Valley, Cal., where scheelite is mined with 

gold.2

Mr. Cox's method of grading the scheelite for shipment to.the buyer is as 

follows: The scheelite ore is dried, cobbed, and picked. As is- usual with most 

scheelite ores, what is apparently pure scheelite will be seen, if examined 

closely, to contain minute stringers of quartz. The specific gravity of chemically pure scheelite (containing 80.5 per cent of WOS ) is 6, that of quartz 

about 2| [really about 2.65]. The specific gravity of a piece of apparently 

pure scheelite was determined by test and found to be 5.42, showing the 

presence of a small amount of quartz as an impurity.

By proportioning the specific gravities of scheelite and quartz it was computed that "pure" scheelite, as found in this mine, contains 84 per cent 

scheelite and 16 per cent quartz, which means an estimated amount of 67.6 per

1 Ball, L. C., Wolfram mines of Mount Carbine, No. 1: Queensland Government Min. 

Jour., vol. 14, p. 70, 1913.

a McDonald, P. B., Scheelite mining and grading: Min. and Sci. Press, vol. 112, pp. 

40-41, 1016.
70 TUNGSTEN MINERALS AND DEPOSITS.

cent of WOs. Continuing this computation, it was determined that ore that 

looked to be three-fourths (by volume) of "apparent" scheelite, as judged by 

the man sorting it, contains 58 per cent of W08 ; that one-half " apparent" 

scheelite contains 46 per cent of WOs; that one-third " apparent" scheelite 

contains 35 per cent of WOs; that one-fourth " apparent" scheelite contains 

28 per cent of tungstic acid. These figures seem high, but the apparent discrepancy is due to the high specific gravity of scheelite as compared with that 

of quartz, it being remembered that the sorting is done by volume.

In the first lot that was shipped, the mine estimate of its No. 1 grade, as 

averaging 65 per cent of WOs, checked closely with the analysis of the buyer, 

which was 65.4 per cent. The second grade, which was judged at the mine 

to be 50 per cent of WOs, proved to be 45.7 per cent. The third grade, estimated at the mine at 25 per cent of WOa, ran 26.2 per cent. In the sorting 

for shipment at the Union Hill mine the No. 1 grade is usually made up of 

apparently pure scheelite; the No. 2 grade embraces the picked ore between 

apparently pure scheelite and one-half apparent scheelite by volume. The 

proportions of the No. 2 grade would thus lie between 46 and 67.6 per cent 

WOs; the final percentage is adjusted after looking it over carefully and would 

be probably nearer to 46 than to 67.6 per cent rather than the numerical 

average, because there is usually more ore slightly above 46 per cent than 

there is slightly below 67.6 per cent. The No. 3 grade is between one-eighth 

and one-half apparent scheelite judged by volume. The usual grades shipped 

are: First, 65 per cent; second, 50 per cent; third, 25 per cent.

Mr. Cox's figures on specific gravities and volumes are as follows: 

With three-fourths apparent scheelite by weight, the other one-fourth assumed to be quartz:

0.75X5.42 (specific gravity apparent scheelite) _____ 4.06 

0.25X2.5 (specific gravity quartz) ____ __ __ .63

Specific gravity of specimens__________:___:_ 4. 69 

Proportion of apparent scheelite by weight, 4.06-5-4.69=87 per cent. 

Proportion of WO3 , 0.87X0.676 (percentage of WO3 in apparent 

scheelite) =58.8 per cent.

With two-thirds apparent scheelite by volume, the other one-third assumed to 

be quartz:

0.67X5.42 _________________________________ 3. 63 

0.33X2.50 ______________ __ . 82

Specific gravity of specimens_ ___ 4. 45 

Proportion of apparent scheelite by weight, 81.5 per cent. 

Proportion, of WOs in specimen, 0.815X0.676=55.1 per cent. 

With one-half apparent scheelite by volume, the other one-half assumed to 

be quartz:

0.5X5.42 _________________________________ 2. 71 

0.5X2.50 __________________-______________ 1. 25

Specific gravity of specimens____________ _ 3._ 96

Proportion of apparent scheelite by weight, 68.3 per cent. 

Proportion of WOS in specimen, 0.683X0.676=46.2 per cent.

With one-third apparent scheelite, the proportion of W03 is 35 per cent.

With one-fourth apparent scheelite, the proportion of WOs is 28 per cent.

With one-fifth apparent scheelite, the proportion of WO8 is 24 per cent.

With one-sixth apparent scheelite, the proportion of WOa is 20.3 per cent.

With one-eighth apparent scheelite, the proportion of WOa is 16 per cent.
PERCENTAGE OF TUNGSTEN IN ORES. 71

The Wolf Tongue Mining Co. originated a method which has been 

used by it and others on the ferberite ores of the Boulder field with 

excellent results, and the constants used there have been found serviceable in other fields. The mode of operation is as follows:

The articles needed are a flask holding about 1,500 cubic centimeters of water and scales weighing in grams up to 3 or 4 kilos. 

The flask is counterbalanced, then 1,500 grams of water is weighed 

into it and the height marked on the neck.

For determinations, 1,300 grams of water is weighed into the flask 

and then dry ore is poured in until the water is raised to the 1,500- 

gram (c. c.) mark. This means, of course, that the ore occupies 200 

cubic centimeters and that an equal bulk of water weighs 200 grams.

The weight of the water in the flask, 1,300 grams, is subtracted 

from the total weight, and the difference, which is the weight of the 

ore, is divided by 200 grams, the weight of the water displaced, thus 

giving the specific gravity, which is compared with a table giving 

the equivalent percentage of W03 .

At the Wolf Tongue mill the table has been elaborated so that 

weights may be directly read into percentages by referring to the 

table, as shown below.

Percentage of tungsten trioxide indicated by iveights of 200 cubic centimeters of 

ferberite ore plus 1,300 cubic centimeters of water, in Boulder field, Colo.

Weight of ore and 

water (grams).

1,815...............

1,820...............

1,825...............

1,830.....:.........

1,835...............

1,840...............

1,845...............

1,850...............

1,855...............

1,860...............

1,865...............

1,870. .......\......

1,875...............

1,880...............

1,885...............

1,890................

1,895 ...............

i onn

1,905...............

1,910...............

1,915...............

1,920...............

1,925...............

i <wn

1,935 ...............

i odn

i cw;

1,950...............

1,955...............

1,965...............

1,970...............

1,975...............

1 980

L986. ..............

Specific 

gravity 

corresponding 

to weight 

of ore.

2.575

2.600

2.625

2.650

2.675

2.700

2.725

2.750

2.775

2.800

2.825

2.850

2.875

2.900

2.925

2.950

2.975

3.000

3.025

3. 050

3.075

3.100

3.125

3.150

3.175

3.200

3.225

3.250

3.275

3.300

3.325

3.350

3. 375

3.400

3.425

Specific 

gravity 

for given 

percentages of 

W08 m 

ore.

2.650

2.650

2.724

.2. 748

2.772

2.796

2.821

2.847

2.873

2.899

2.925

2.951

2.979

3.007

3.035

3.063

3.096

3.129

3.162

3.195

3.228

3. 263

3.296

3.329

3. 362

3. 395

3.432

Percentage 

of W08 in 

ore.

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

Weight of ore and 

water (grams).

1,990...............

2,000...............

2,005...............

2,010...............

2,015...............

2,020...............

2,025...............

2,030...............

2,035...............

2,040..........:....

2,045...............

2,050...............

2,055...............

2,060...............

2,065...............

2,070...............

2,075...............

2,080...............

2,085...............

2,090...............

2,095...............

2,100...............

2,105...............

2,110...............

2,115...............

2,120...............

2,125...............

2,130...............

2,135...............

2,140...............

2,145...............

2,150...............

2,155...............

2. 160....... .........

2,165...............

Specific 

gravity 

corresponding 

to w.eight 

of ore.

3.450

3.475

3.500

3.525

3.550

3.575

3.600

3.625

3.650

3.675

3.700

3.725

3.750

3.775

3.800

3.825

3.850

3.900

3.925

3.950

3.975

4.000

4.025

4.050

4.075

4.100

4.125

4.150

4.175

4.200

4.225

4.250

4.275

4.300

4.325

Specific 

gravity 

for given 

percentages of 

WOain 

ore.

3.471

3.510

3.549

3.588

3.629

3.673

3.717

3.761

3.805

3.850

3.899

3.948

3.997

4.046

4.094

4.155

4.211

4.267

4.323

Percentage of 

WOsin 

ore.

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44
72 TUNGSTEN MINEBALS ANr DEPOSITS*

Percentage of tungsten trioxide indicated ~by iceights of 200 cubic centimeters of 

ferberite ore, etc. Continued.

Weight of ore and 

water (grams).

2,170..........:....

2.175...............

2.180...............

2.185...............

2.190...............

2.195...............

2,200...............

2,205...............

2,210...............

2,215...............

2,220...............

2,225...............

2,230...............

2,235...............

2,240...............

2,245...............

2,250...............

2,255...............

2.260...............

2,265...............

2,270...............

2,275...............

2,280...............

2,285...............

2,290...............

2,295...............

2,300...............

2,305...............

2,310...............

2,315...............

2,320...............

2,325......:........

2,330...............

2,335...............

Specific 

gravity 

corresponding 

to weight 

of ore.

4.350

4.375

4.400

4.425

4.450

4.475

4.500

4.525

4.550

4.575

4.600

4.625

4.650

4.675

4.700

4.725

4.750

4.775

4.800

4.825

4.850

4.875

4.900

4.925

4.950

4.975

5.000

5.025

5.050

5.075

5.100

5.125

5.150

5.175

Specific 

gravity 

for given 

percentages of 

W03 in 

ore.

4.383

4.448

4.513

4.578

4.643

4.709

4.783

4.858

4.933

5.008

5.088

5.177

Percentage 

of W03 in 

ore.

45

46

47

48

40

50

51

52

53

54

55

56

Weight of ore and 

water (grams).

2,340...............

2,345...............

2,350...............

2,355...............

2,360...............

2,365...............

2.370...............

2.375...............

2,380...............

2.385............... 9 son

2,400...............

2,405...............

2,410...............

2,415...............

9 49(1

2,425...............

2,430...............

9 431

2,440...............

2,445...............

2,450...............

2,455...............

2,460...............

2.465...............

2,470...............

2,475...............

2,480...............

2,485...............

2,490...............

2,495...............

2,500...............

2,505...............

2,510...............

Specific 

gravity 

corresponding 

to weight 

of ore.

5.200

5.225

5.250

5.275

i s(vi

H Q91

5.350

5 971;

5.400

5 49<;

5.450

5.475

5.500

5.525

5 ^<;n

5.575

5.600

5.625

5.650

5.675

5.700

5

7OK

5.750

5.775

5.800

5 one

5.850

5.875

5 onn

5

QOC

5.950

6.000

6.025

6.050

Specific 

gravity 

for given 

percentages of 

W03 in 

ore.

5.266

5.355

5 444

5.553

5.639

5.745

5.851

5.957

6.060

Percentage of 

Wb3 in 

ore.

57

58

59

, 60

61

AO

63

64

65

The figures given are, of course, not exact specific gravities but 

are approximations close enough to give valuable data as to the 

probable metallic content of the ore. Such a- method is applicable 

wherever there are.no other heavy minerals in the ore and wherever 

the gangue is of fairly constant composition. Corrections would have 

to be made for use with particular ores. For example, the specific 

gravity of the Boulder ferberite is 7.499, or, say, 7.5, and the specific 

gravity of scheelite is about 6, so that for equally high percentages 

the scheelite ore, if free from heavy minerals, such as galena, pyrite, 

and hematite, will have a somewhat lower specific gravity.

J. J. Runner 1 has described experiments in determining the percentage of WO3 present in wolframite and scheelite ores by measuring the specific gravity and has constructed curves, largely interpolated (see fig. 4), to show the relations between the values. Very 

small quantities of ores were used, and comparatively few points on 

the curves \vere determined.

A beautifully simple process used in the Atolia district and said 

to give excellent results is briefly described as follows: 2

1 Runner, J. J., Specific method for tungsten analysis: Min. and Sci. Press, vol. 133, 

pp. 11-13, 1916. 

3 See appendix.
QUALITY OF ORE DEMANDED BY USERS. 73

A graduate with a scale reading to 1,000 cubic centimeters is filled 

with water to the 500 cubic centimeter mark. Into it a weighed 

quantity of ore, about 500 grams, is poured and a reading again 

taken. The difference represents a quantity of water equal in bulk 

to that of the ore. A cubic centimeter of water at 4° C. (38° F.) 

weighs a gram, so that the water displaced may be read as grams 

instead of cubic centimeters. Dividing the weight of the ore by this 

weight gives the specific gravity, and by comparison with a table

7.1

6

Q

6.5

c o

6.1

UJ , q K 5- 9

0 57 u.'

0, 5.5 

> ' 53

>5,

tY L. Q

o

o. * '

\L 4.5

O / 3 u *-J

Q- 4.1

</)

3.7

O.d 

00

3

1

0 Q

2.7 -" ^

 s^

/

s

V-" / 

/

/

/

/

/

' ,

s

/

/

-£

y

/

A*/

/

s

4

y

<£/

/

/

y$

/

/

e. t

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1

/

/

y

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/

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/

/

/

/

/

/

/

/

/

04 8 12 16 20 24 28 32 36 40 44 48 52 56 60 64 68 72 76 80 

PERCENTAGE OF WO3 IN ORE

FIGURE 4. Curves showing the relations between the specific gravity of tungsten ores 

and the percentage of contained WOs. (After J. J. Banner.)

similar to that given for ferberite ores or a diagram like that of 

Runner's the approximate percentage is at once obtained.

In all the determinations of specific gravity in which water is used 

trouble is had in thoroughly wetting the tungsten ore. Unless the 

ore is boiled air bubbles persist and the results are by so much made 

less reliable. To avoid this trouble the method followed in obtaining the specific gravity of cement is employed that is, kerosene 

or benzene (62° naphtha) is used as a comparative medium. If the 

ore is dry the oil wets it immediately, and the method is said to give 

very accurate results, especially for ores carrying more than 30 per
74 TUNGSTEN MINERALS AND DEPOSITS.

cent W03 . The method as applied to cement is carefully described 

by T. B. Stillman.1

QUALITY OF ORE DEMANDED BY USERS.

Inquiries were addressed by the Geological Survey to firms known 

to be reducing tungsten ores, asking what, for their purposes, was the 

relative desirability of the tungsten-ore minerals, the impurities 

most hurtful, and the limiting percentages of impurities that would 

be accepted.

Eight firms courteously gave the desired information in considerable detail, and another with less detail.

Of these firms, one reduces its ores by fusing with sodium carbonate (Na2C03 ), leaching with water, separating tungsten trioxide 

(W03 ) by hydrochloric acid, and reducing the trioxide to a metallic 

powder; two reduce the ores by other wet chemical processes; two 

use both the sodium carbonate fusion process and direct reduction 

in an electric furnace; two use an electric furnace only; one uses 

processes in which the ores are first treated with wet chemicals and 

reduction is then completed in an electric furnace. Another firm, 

the Crucible Steel Co., has in use a number of processes, part of 

which are covered by the Johnson patents.2

By the sodium carbonate fusion process only powdered metallic 

tungsten is obtained. One of the other wet chemical processes produces powdered tungsten and another makes powdered f erro-tungsten. 

The electric furnaces produce only ferro-tungsten.

Most of the processes used for reducing tungsten from its ores 

also partly or wholly reduce nearly all the metallic and some other 

impurities in the ores, and these impurities are carried with the tungsten into the steel to which it is added. For such use iron makes 

no difference, but a number of other elements are not wanted, either 

because, like copper and phosphorus, they are detrimental to the 

steel or because, like manganese, if they are wished in the steel they 

can be added more advantageously in some other way.. Objectionable 

impurities found in tungsten ores are antimony, arsenic, bismuth, 

copper, lead, manganese, nickel, tin, zinc, phosphorus, and sulphur. 

Few of these occur in large quantity in ores found in this country. 

Copper is perhaps the commonest hurtful impurity, and therefore 

most is said about it, but ores from some foreign countries contain 

nearly all the impurities mentioned. During the early part of 1916 

tungsten ores were so eagerly sought that nearly all offered were 

bought with little objection to impurities, but under more normal 

conditions consumers are much more particular.

1 Stillman, T. B., Engineering chemistry, 4th ed., pp. 343-348, 1910. 

£ Johnson, C. M., U. 8. patents 064868, 964869, 964870, 964871, 977096.
QUALITY OF ORE DEMANDED BY USERS. 75

The wet chemical processes give more opportunity to get rid of 

most impurities than the electrolytic process, so that companies 

using wet chemical processes are, as a rule, though not uniformly, 

least particular about the ores they buy. Two of the firms that use 

wet chemical processes buy tungsten ores almost without regard to 

the impurities present, but one objects to more than 2 per cent 

copper, and both buy ores containing as little as 20 per cent W03 .

Only the one firm mentioned is known that does not object to 

copper in any grade of ore. Another will take cupriferous ore if 

"the content of WO3 is sufficiently high." The others either will 

not take copper-bearing ore when other ores are to be obtained or 

set limits of 0.2 to 2.0 per cent copper and not less than 50 per cent 

W03 , except that one firm will take ores that carry 5 per cent or 

more copper, for such a percentage will pay for separation.

Two companies take ores without regard to impurities other than 

copper, provided the content of W03 is sufficiently high. Most of 

the companies object to tin, sulphur, phosphorus, antimony, arsenic, 

bismuth, lead, and zinc, two of them object to manganese, and one 

to nickel. The last company referred to set extreme limits of 0.25 

per cent for phosphorus, 0.25 per cent for nickel, 6.0 per cent for 

manganese, and a trace of arsenic.

As to the different tungsten ore minerals ferberite, wolframite, 

hiibnerite, and scheelite two companies using wet chemical processes 

reported that they made no discrimination; a company using both 

processes reported that it made no discrimination if the ores carried 

more than 60 per cent W03 ; one company uses ferberite and scheelite 

and will not use wolframite or hiibnerite; another prefers scheelite 

but will take any tungsten ore mineral; a user who does not make 

steel and whose product does not enter into steel also prefers scheelite. 

Three others gave their estimates of the comparative values as follows (the estimates being stated in the same order): If ferberite 

can be bought at $7 per unit then wolframite is worth $7, $6.30, 

$6.25; hiibnerite, $6.50, $5.60, $6.25; scheelite, $6, $6.60, $6.50.

So far as can now be learned, the foreign buyers are quite as 

various in their demands as the domestic users and are in general 

more strict in the limits set, and they also demand a purity of 65 

to 70 per cent W03 , which means loss in concentration, for ores can 

not ordinarily be concentrated to so high a percentage without great 

waste in slimes.

Brokers are naturally ruled by the consumers to whom they sell 

and make the same restrictions as to quality of the ores bought:

From the very different ways in which the ores are valued by 

different buyers, it will be seen that, in general, a seller should know 

the market well, especially what the different buyers will pay, before 

disposing of his product.
APPENDIX.

Note 1, p. 34. Yellowish minerals which owe their color to iron 

and contain no tungsten coat tungsten minerals in many places and 

are frequently mistaken for tungstite. Such a substance is found in 

a number of the ferberite mines of Boulder County, but, unlike tungstite, it is soluble in hydrochloric acid and is unaffected by ammonia. 

No tungstite is known to have been found in the Boulder field.

Note 1, p. 37. The same remarks apply to gneiss, which may be 

considered as a very coarse schist. Thus in the Boulder County 

tungsten field the ferberite veins that lie in the gneisses are rarely 

of value, though the veins may be rich in the adjoining granite or 

along a contact between granite and gneiss.

As used in this bulletin the term schist indicates a metamorphic 

rock in which the minerals are disposed in parallel planes so as to 

give it a distinct, fairly closely spaced cleavage. In gneiss also the 

minerals, or a part of them, usually the dark minerals, are disposed 

in parallel planes; but gneiss has a poor cleavage or none at all.

Note 4, p. 39. Hugh Watts, the well-known assayer of Boulder, 

Colo., says that hiibnerite has been found in small particles in roscoelite, the vanadium mica, on a claim on Governor Hill, on the northwest side of Left Hand Canyon, near Jamestown, Colo. This locality 

is at the northeast side of the Boulder tungsten field. Roscoelite,

therefore, is also to be added to the list.

Note 1, p. 40. The remarks on quartz in the Boulder veins apply 

only to the ordinary varieties of milky or clear quartz. In many of 

the veins in the Boulder field there is a considerable quantity of 

"horn," or "horn rock," as it is locally known (from its resemblance 

to horn), that is a very fine grained quartz. It is partly a vein 

deposit and partly formed by the replacement of granite. In one 

deposit it reached a width of 10 feet and was cut by thin veins of 

very fine grained ferberite. The " horn " is usually gray, but some is 

white and some reddish. It is usually older than the ferberite but 

is in part of the same age.

In the Atolia field a somewhat similar form of quartz is found in 

the scheelite veins, but in smaller quantity.

Note 2, p. 46. A small specimen from the dump of the Wild Cat 

Leasing Co.'s workings at White Oaks, N. Mex., is composed of 

hiibnerite penetrated by tiny crystals of gold. 

76
APPENDIX. 77

In the Logan mine at Crisman, Boulder County, Colo., free gold 

has been found embedded in ferberite.

Note 1, p. 48. Pyrite is becoming much more plentiful in some of 

the ferberite veins of Boulder County as depth is reached, and it 

forms a considerable part of a few ores, but as compared with some 

fields this field still shows pyrite in small quantity. Beautiful light 

greenish-yellow crystals of sphalerite form crusts in vugs at one end 

of a shoot in a ferberite vein in Gordon Gulch, in the Sugar Loaf 

district of the Boulder tungsten field.

Note 1, p. 50. Very rich sylvanite is found at the junction of a 

gold-bearing vein and a ferberite vein in the Eed Signe mine at Ferberite, Boulder County, Colo. H. Gillingham Hibbs believes that 

the gold-bearing vein is the older.

Note 1, p. 52. In some of the deeper workings of the Boulder tungsten field specular hematite is becoming prominent. Concentrates are 

found to carry a considerable excess of iron oxide over the theoretical quantity which should be contained, and when ores from some 

mines are treated the concentrating tables, especially the longer 

ones, 14 or. 15 feet in length, separate a very distinct reddish-brown 

streak of iron oxide next to the inner side of the ferberite streak. 

The hematite is fairly well distributed over the field. The presence 

of this hematite makes trouble in estimating the percentage of W03 

in the ore by specific-gravity determinations (see p. 71), and may 

account for the greater density of the deeper ores in other fields (see 

p. 69). The hematite is probably, in part at least, leached from the 

surface ores.

Note 1, p. 63. The connection or lack of connection between the 

pegmatite dikes and the veins needs much more study. In a reconnaissance of the Boulder field since this bulletin was in type I have 

made some further observations on these relations. In the ferberite 

veins of the field the ferberite is commonly later than the older 

"horn" (fine-grained quartz, which may be of two ages). Thus the 

outer parts of the vein may be of " horn " and the center of nearly pure 

ferberite, as in parts of the Luckie 2 vein, near Boulder Falls. This 

vein cuts a pegmatite dike about 5 inches thick at a sharp angle, and 

although on each side the vein contains " horn," in the pegmatite it 

contains none. I saw no " horn " in any of the veins cutting pegmatite. I do not believe that this is due to a difference in the composition of the pegmatite and the country granite, but it seems to 

mean that the pegmatite was intruded during the formation of the 

veins, after the older "horn" at any rate and before the ferberite. 

It is possible that there were several periods of pegmatitic intrusion, 

and some may be entirely older than the veins.
78 TUNGSTEN MINERALS AND DEPOSITS.

Note 2, page 72. The method as outlined in the text is given as 

described by a visitor to the plant. Mr. Marshall D. Draper gives 

the following authoritative details:

I bought a great many small lots of scheelite ore from the various small 

producers, principally from small placer operations, in 1916, and to facilitate 

these small purchases devised a set of specific-gravity tables which I am 

sending herewith, thinking they may be of some interest. These were checked 

by analyses at various times, and the table was found to be quite accurate. 

Naturally a buyer had to be careful that extraneous material was not included 

in scheelite offered for sale. The principal thing I had to look out for was 

barite. On one or two occasions there were attempts made to include some 

with the scheelite, but it was generally a simple matter to discover the presence 

of barite1 or other such components.

It is of interest also to note that the curve for scheelite concentrate 

made in the local plant at Johannesburg, which was installed by me, does not 

at all follow the curve for crude ore. I made no definite attempt to ascertain 

the cause of difference, but the difference nevertheless remained. The table 

was based on the assumption that the mineral was scheelite and the gangue 

was quartz. The small amounts of dolomite or calcite contained in the vein 

material did not, as might have been assumed, make a material difference 

in the estimate of content. By means of these curves I was able to buy outright many small lots of ore and pay the producer without waiting for an 

analysis. Most large lots were, of course, bought by preliminary payment on 

the basis of specific gravity and final settlement on analysis.

The apparatus used by me in making these specific-gravity determinations 

was a small scale for weighing out from 1 to 4 kilos of the scheelite ore. I had 

a 2,000 cubic centimeter glass graduate which was about 18 or 20 inches in 

height and some 2$ inches in diameter. I filled this'with water, generally for 

convenience to the 1,000 cubic centimeter mark, and then introduced the charge 

of 1 or more kilos. The displacement of the ore was noted and the specific 

gravity calculated from it. Then by reference to my chart, which was being 

made more accurate all the time by reason of the various analyses to check 

the specific gravity, I was able to get at an extremely close idea of the contentso close, in fact, that I latterly came to rely more on it than on analyses, more 

particularly for the reason that at that time many chemists used different 

schemes and there were many discrepancies between them for a time.

Later I made also the accompanying table of specific gravity as against WO,

o

content and did not then have to refer to the chart.

It may be of interest to note that I always required scheelite ores to be clean 

that is, with the usually accompanying magnetite removed, as it is quite evident 

that otherwise my specific-gravity determinations would have been vitiated..

1 The presence of barite and other impurities In tungsten ores must of course be carefully noticed. One tungsten buyer was financially ruined in 1916 through buying, on 

specific-gravity tests, scheelite ores salted with barite. F. L. H.
APPENDIX. 79

The table compiled by Mr. Draper and Mr. F. H. Lerchen is as 

follows:

Per cent of tungsten trioxide indicated by specific gravity of scheelite ores of

the Atolia/field.

Specific 

gravity.

3.00

3.10

3.20

3.30

3.40

3.50

3.60

3.70

3.80

3.90

4.00

4.10

4.20

4.30

4.40

4.50

4.51

4.52

4.53

4.54

4.55

4.56

4.57

4.58

4.59

4.60

4.61

4.62

4.63

4.64

4.65

4.66

4.67

4.68

4.69

4.70

4.71

4.72

4.73

4.74

4.75

4.76

Per cent.

15.40

18.40

21.20

24.50

' 28. 00

31.20

34.00

37.00

39.60

42.20

44.80

47.30

49.60

51.60

54.00

56.20

56.40

56.70

57.00

57.30

57.50

57.60

57.80

58.00.

58.20

58.40

58.60

59.00

59.20

59.30

59.50

59.80

60.00

60.10

60.20

60.40

60.60

60.70

61.00

61.20

61.40

61.60

Specific 

gravity.

4.77

4.78

4.79

4.80

4.81

4.82

4.83

4.84

4.85

4.86

4.87

4.88

4.89

4.90

4.91

4.92

4.93

4.94

4.95

4.96

4.97

4.98

4.99

5.00

5.01

5.02

5.03

5.04

5.05

5.06

5.07

5.08

5.09

5.10

5.11

5.12

5.13

5.14

5.15

5.16

5.17

5.18

Per cent.

61.80

62.00

62.00

62.10

62.20

62.40

62.80

63.00

63.20

63.30

63.40

63.60

63.70

63.80

64.10

64.20

64.30

64.40

64.50

64.70

64. 80

65.00

65.20

65.40

65.50

65.60

65.80

66.00

66.10

66.30.

66.40

66.60

66.80

66.90

67.00.

67.10

67.20

67.30

67.60

67.70

67.80

67.90

Specific 

gravity.

5.19

5.20

5.21 ,

5.22

5.23

5.24

5.25

5.26

5.27

5.28

5.29

5.30

5.31

5.32

5.33

5.34

5.35

5.36

5.37

5.38

5.39

5.40

5.41

5.42

5.43

5.44

5.45

5.46

5.47

5.48

5.49

5.50

5.51

5.52

5.53

5.54

5.55

5.56

5.57

5.58

 5.59

Per cent.

68.00

68.10

68.20 '

68.40

68.50

68.60

68.70

69.00

69.10

69.20

69.40

69.60

69.70

69.80

70.00

70.10

70.20

70.40

70.60

. 70.70

70.80

71.00

71.10

71.20

71.30

71.40

71.50

71.60

71.70

71.80

71.90

72.00

72.10

72.24

72.36

72.48

72.60

72.72

72.84

72.96

73.08

Specific 

gravity.

5.60

5.61

5.62

5.63

5.64

5.65

5.66

5.67

5.68

5.69

5.70

5.71

5.72

5.73

5.74

5.75

5.76

5.77

5.78

5.79

5.80 -

5.81

5.82

5.83

5.84

5.85

5i86

5.87

5.88

5.89

5.90

5.91

5.92

5.93

5.94

5.95

5.96

5.97

5.98

5.99

6.00

Per cent.

73.20

73.30

73.40

73.50

73.60

73.70

73.80

73.90

74.00

74.10

74.20

74.32

74.44

74.56

74.68

74.80

74.92

75.04

75.16

75.28-

75.40

75.54

75.68

75.82

75.96

76.10

76.24

76.38

76.52

76.66

76.80

76.94

77.08

77.22

77.36

77.50

77.64

77.78

77.92

78.06

78.20

INDEX.

A. Page.

Adularia, association of, with tungsten ____________ 54

Africa, tungsten In ____'. ______ 33,51

Alaska, tungsten in__________ 31,

43-44, 48, 50, 51, 55

Apatite, description of________ 31, 50

resemblance of, to scheelite _ 31

tungsten and _______ _ 56

Argentina, tungsten in______-_ 28

Arizona, cuprotungstite from, plate

showing.-___ _ 32 

ferberite from, plate showing_ 32, 38 

hiibnerite from, plate showing_ 30 

scheelite from, plate showing 30 

tungsten, in______________ 25,

27,- 28, 31, 33, 37, 41, 45, 

50, 52-53, 55, 57, 60, 64 

wolframite from, plate showing. 39 

Arsenopyrite, association of, with

tungsten _________ 46

Asia, tungsten in________ 28, 31, 44, 51

Atolia, Cal., scheelite from____ 76,78-79

scheelite from, plates sho\ving__ 30,

44, 50, 52

stibnite from, plate showing-_ 50

Australia, tungsten in_________ 25,

. 27, 28, 31, 33, 35, 39, 42,

44, 46, 49, 51, 53, 54, 55, 58

See also New South Wales.

Austria, tungsten in_______ 28, 35, 51

wolframite from, plate showing. 28

B..

Ball, L. C., on tenor of tungsten

ore ____________ 69

Baltic Gulch, Cal., scheelite from,

plate showing __ 44

Bancroft, Howland, on tungsten deposits__________ 7-8

Barite, resemblance of, to scheelite__________ 30-31, 78

Beryl, description of____ _ _ 54 

tungsten and _________ __ 54

Birdie mine, Mont., hiibnerite from,

plate showing______ 24

Bismuth, description of____ _ 45 

tungsten and __ _ 45

Bismuthinite, character of___ _ 46 

tungsten and ______ 46

Black Metal claims, S. Dak., wolframite and cassiterite 

from, plate showing_ 50

47154° Bull. 652 17 6

Page. 

Blue Grouse Mountain, wolframite

from___________ 38

wolframite from, plate showing- 38

Bohemia, tungsten in_________ 28, 35

wolframite from, plate showing- 28

Bolivia, tungsten in___________ 28, 46

Boulder, Colo., ferberite at____ 24,'76, 77 

Brazil, tungsten in___ ______ 35

British Columbia, tungsten in__ 25, 34, 60 

tungstite from, plate showing_ 30 

Broken Hill, New South Wales, stolzite from, plate showing _______ 30 

Butte, Mont., biibnerite from, plate

showing _ _ 24

C.

Calaverite, association of, with

tungsten ___ 50 

Calcite, description of_________ 53

resemblance of, to scheelite- 31, 53-54 

California, scheelite from, plates

showing__ 27, 30, 44, 50, 52

tungsten in 28,

30, 40-49, 51-53, 55, 60

veins of, depth of:______ 62,63

wolframite from, plates showing__________ 24,27,30 

Canada, tungsten in _ 27,57 

Game, T. E., on tungsten veins__ 61 

Cassiterite, description of_______ 51

tungsten and _ _ 51 

Cave Creek, Ariz., cuprotungstite

from__________ 32 

ferberite from, plates showing____________ 32,38 

Chalcedony, description of 51 

tungsten and 51 

Chalcocite, association of, with

tungsten __ 46-47 

Chalcopyrite, association of, with

tungsten _ 47 

Chase, E. E., on tungsten veins 65 

Chile, tungsten in________ 33,35

Chlorite, association of, with tungsten __ ___ 54 

Cinnabar, association of, with tungsten 47 

association of, with tungsten,

plate showing. . 24 

Clark Mountains, scheelite from,

plates showing__ 27,30

81
82 INDEX.

Page. 

CJark Mountains, wolframite from,

plates showing__ 24,27,30 

Clifton district, Utah, scheelite

from, plates showing- 30,32

ferberite from, plates showing 22,

23, 24, 26, 44, 52

hiibnerlte from, .plate showing_ 24

scheelite from, plate showing _ 30

tungsten in___ 24-25,26,40,41-42,

45-48, 50-52, 54, 56

veins of, depth of______ 62-63

Columbite, association of, with

wolframite_______ 57 

resemblance of, to wolframite_ 28 

Columbium oxide, association of,

with tungsten ____ 57-58

Coming Power claim, Utah, scheelite from, plate showing____________ 30 

Conger mine, Colo., ferberite from,

plate showing ____ 52 

Connecticut, tungsten in__ 31, 36, 41, 49 

Contact-metamorphic deposits, formation of ______ __ 42-43

tungsten in____________ 43-44 

Copper, hurtfulness of, in tungsten

ores ___________ 74 

Cornwall, tungsten In_________ 28, 

38-39, 42, 44, 51, 57 

wolframite from, plate showing- 28 

veins of, depth of_._____ 61 

Cosallte, association of, with tungsten ___________ 47 

Covelllte, association of, with tungsten .____________ 47 

Cox, A. D., on tenor of tungsten ore_ 69-70 

Crow patent, Colo., ferberite from,

plate showing_____, 22

Cuprotungstite, composition of___ 32

distribution of __________ 33

origin of ___________ 64

physical features of_______ 32-33 

plate showing___________ 32

D.

Deep Creek Mountains, Utah, scheelite from, plates showing____________ 30,32

D'Elhujar, Juan, Jose", and Fausto, 

tungsten discovered 

by_____________ 11-12

Dewey, Henry, on tungsten veins - 61

Dikes. See Pegmatite dikes.

Dolomite, association of, with tungsten___________ 53

Dragoon, Ariz., scheelite from, plate

showing_________ 30

E.

Electric lights, filaments for____'. 17-18 

England, tungsten in_________ 29

See also Cornwall. 

Enrichment, secondary, occurrence

of_____________ 64-65 

Epidote, resemblance of, to scheelite- 30

P. Page.

Ferberite, composition of 22 

crystals of 21 

distribution of-_ 24-25 

importance of 25 

physical features of_ ____ 22-24 

minerals resembling____ 24, 76, 77 

pegmatite and ____ _ 77 

plates showing 22, 

23, 24, 26, 32, 38, 44, 50, 52 

price of__________-__ 25,75 

streak of____ ___ 23 

veins of, outcrops of______ 60

Ferritungstite, occurrence and character of_______ _ 34

Fink, C. G., oh properties of tungsten___________ 13 

on tungsten lamps . 17

Fluorspar, description of_______ 50 

tungsten and ___ __ _ 50-51

France, tungsten in 25, 28

G.

Galena, description of 47 

tungsten and 47 

Garnet, resemblance of, to hiibnerite________ 26 

resemblance of, to scheelite- 30 

George, R. D., on tungsten veins 63 

Georgia- A mine, Colo., ferberite

from, plate showing_ 23 

Germany, tungsten in____ 27, 28, 42, 51 

Gladstone, Colo., hiibnerite from,

plate showing 24

Gneiss, ferberite in___________ 76

Gold, association of, with tungsten- 33,

36, 45-46, 76, 77

Golden Chest mine, Idaho, scheelite

from, plate showing_ 30 

Good Luck claim, S. Dak., ferberite

in, plate showing 50 

Granitoid rocks, tungsten associated

with___________ 35 

Graphite, tungsten associated with_ 46 

Gray, G. J., and Winters, R. J., on

tungsten veins ___ 62 

Greenland, tungsten In _ __ 25

H.

Hamlinite, occurrence of______ 56

tungsten and 56

Hematite, description of , 52

' tungsten and ___:______ 52-53, 77

Hematite, specular, resemblance of,

to ferberite_______ 24,52 

resemblance of, to wolframite_ 28 

Hess, F. L., on tungsten deposits 8 

Hess, F. L., and Schaller, W. T.,

on tungsten minerals. 8 

Hill, J. M., on tungsten deposits__ 8 

Hill City, S. Dak., cassiterite from,

plate showing____ 50 

ferberite from, plate showing 50 

Hobbs, W. H., on tungsten deposits- 8 

Hoosier mine, Colo., ferberite from,

plate showing-,. 23
INDEX. 83

Page.,

Hornblende, resemblance of, to -wolframite ____ _ 28 

Hiibnerite, composition of 22 

crystals/of 21 

distribution of 26-27, 76 

importance of 27 

minerals resembling 26 

physical features of 25-26 

plates showing______ 24, 26, 30, 45 

price'of_______ 27,75 

silver and, association of 36 

streak of- 26 

veins of, outcrop of_ _ GO 

Humbug district, Ariz., wolframite

from, plate showing H9

I.

Idaho, scbeelite from, plate showing. 30 

tungsten from____ 25, 26, 31, 46-50, 60 

Ilmenite, resemblance of, to ferberite____________ 24 

India, tungsten in 25 

Italy, tungsten in ___ 25, 49

J.

Jack claim, Cal., scheelite from,

plates showing.____ 27, 30 

' A wolframite from, plates showri] ing __________ 24,27,30 

Japan, scheelite, ferberite, and 

tungstite from, plates 

showing 32 

tungsten in 28,31 

Jardine, Mont, scheelite from,

plate showing 30 

Johnson, B. L., on tungsten deposits _ 8

K.

Klmberly - Montana mine, Mont., 

scheelite from, plate 

showing ' 30

Knopf, Adolph, on tungsten deposits____ _ 8-9

Kootenay Belle mine, tungstite

from____ _ 33

tungstite from, gold with____ 33-34

plate showing _ 30

Kurasawa mine, tungsten from,

.plate showing _____ . 32

L.

Lamp filaments, tungsten used for__ 17-18 

Lead, S. Dak., scheelite from, plate

o showing__ ___ 30 

Leadville, Colo., scheelite from,

plate showing _ __ 30 

Lepidollte, description of 55 

tungsten and _ _ ___ 55 

Lindgren, Waldemar, on tungsten

veins ___________ 62-63 

Lower California, tungsten in 33 

Lucln, Utah, scheelite from, plate

showing ___ 30

M. Page.

Magnetite, resemblance of, to ferberite__________ 24 

resemblance of, to wolframite 28 

Magnet steels, tungsten in _ 17 

Maine, tungsten in_______ - 38 

Manganese dioxide, resemblance of,

to wolframite_____ 28 

Massachusetts, tungsten in__ - 35 

Melville, W. H., on powellite____ 19 

Mexico, scheelite from,, plate showing___________ 30 

tungstite from, plate showing_ 30 

Meymacite, discovery of_______ 33 

Minerals, associated with tungsten- 39-40 

Minerals, objectionable, in tungsten

ores _ 74-75

Missouri, tungsten in__ 35, 36, 47, 48, 55

Molybdenite, description of_____ 47-48

tungsten and __________ 48

Montana, htibnerite from, plate

showing--_ _ 24 

scheelite from, plate showing 30 

tungsten from ______ 38-39, 46, 47 

Murray, Idaho, scheelite from, plate

showing_________ 30

Muscovite, description of_______ 54

tungsten and _________ 54

N.

Nederland, Colo., ferberite from,

plates showing 22, 44, 52 

Nevada, htibnerite from, plate showIng _, _ 26 

scheelite from, plates showing_ 30, 32 

tungsten in _ __ 26, 

34, 43, 44, 45, 46-48, 50-53, 56, 57, 60 

New Mexico, tungsten in_______ 25, 

26, 28, 33, 35, 38, 43, 

45, 46, 48, 49, 50-51, 55 

wolframite from, plate showing- 24 

New South Wales, cuprotungstite

from, plate showing_ 32

scheelite from, plate showing_ 32

veins of, depth of______ 61-62

stolzite from, plate showing_ 30

tungsten in_____________ 25,

27, 28, 31, 33, 35, 39,

42, 46, 49, 53, 55, 58

New Zealand, tungsten in_____ 31, 46, 49

Nipton, Cal., scheelite from, plates

showing__________ 27, 30 

wolframite from, plates showIng__________ 24,27,30 

Nova Scotia, scheelite from, plate

showing_________ 30 

tungsten in_____________ 31 

Nugget mine, Colo., ferberite from,

plates showing____ 22, 24

0.

Opal, description of_

tungsten and _

Oregon, tungsten in

52
84 INDEX.

r. Page.

Pacific coast, tungsten on _ . 3G

Papoose mine,' Colo., scheelite from,

plate showing_____ 30 

/Pegmatite dikes, formation of_J__ 37-38 

outcrop of _, ____ 60 

tungsten in______ 38-39, 58-59, 77 

minerals associated with_ 58 59 

Pellegrin, A. L., on wolframite __ 27 

Peru, tungsten in _ 27 

Placers, formation of_________ 44 

search for_____________ 66 

tungsten in__________ 44-45, 60 

Portugal, tungsten in _ 28 

Powellite, tungsten in_ ____ 19 

Prospecting, guides in___ _ 65-66 

Pyrite, tungsten associated with__ 48, 77 

Pyroxene, resemblance of, to wolframite -_'. _________ 28

Q.

Quartz, description of________ 52

tungsten and ___________ 52, 76

R.

Raspite, occurrence and character of _ 35 

origin of ! 65 

Regan district, Nev., htibnerite from,

plate showing _ _ 26

Replacement deposits, formation of_ 41

tungsten in ___'__ 40-42

Rocky Mountain States, tungsten in_ 36

Rollinsville, Colo., ferberite from,

plate showing-__ _ 26 

Roscoelite, htibnerite in ______ 70 

Runner, J. J., on tungsten analysis- 72 

Rutile, resemblance of, to htibnerite- 26

S.

Schaller, W. T., and Hess, F. L., on

tungsten minerals _ 8 

Scheele, K. W., tungsten discovered

by____________ 11

Scheelite, crystals of_________ 21.

distribution of__________ 30,31

gold and, association of____ 36

importance of___________ 32 

minerals resembling ____ 30-31, 78 

physical features of______ 29-30 

plates showing__ 27,30,32,44,50,52 

price of ___________ __ 32,75 

tungsten in__________ 11, 78-79 

Scheelite, Nev., scheelite from, plate

showing _-______ 30

Schist, definition of_________1__ 70

Segregation deposits, formation of_ 37 

 tungsten in__________ 37

Siberia, tungsten in__________ 25, 27 

Siderite, description of ________ 53

Silver, tungsten associated with_ 36, 46, 48 

Sonora, Mex., scheelite from, plate

showing-________ 30 

tungstite from, plate showing_ 30

Page. 

South Dakota, ferberite from, plate

showing- ______ 50

scheelite from, plate showing 30

tungsten in___ . 28, 35, 38, 41, 42, 46,

51, 55, 56, 58, 60, 64

wolframite and cassiterite from,

plate showing-- ___ 50 

Spain, tungsten in_________ 24,28,51 

Sphalerite, association of, with

htibnerite______ 48-49, 77

resemblance of,'to hiibuerite__ 26

Stibnite, description of-_______ 49

tungsten and _ __ ___ 49-50

plate showing.________ 50

Stolzite, occurrence and character.

of_____,_______ 34-33 

origin of __ _ 65 

plate showing___ _______ 30 

Sylvanite, association of, with tungsten _ _ _ 50, 77

T.

Tantalum oxide, association of, with

tungsten ________ 57-58 

Tasmania, tungsten in ________ 28

Technical terms, defense of_ __ 10-11 

Tetrahedrite, description of______ 50

tungsten and ______ __ 50

Texas, tungsten in___________ 36, 51 

Topaz, description of_________ 55

tungsten and __________ 55

Tourmaline, description of______ 55

tungsten and ___________ 55-56

Triplite, association of, with tungsten ____________ 57 

Tungsten, alloying with, methods of_ 17 

alloys of_______________ 14-15 

chemical symbol for _____ 12 

compounds of ________ _ 14-15

description of__________ 11-15 

discovery of _____ _- _ 11

ductility of 1__________ 12,18

figure showing______ 13

field tests for___________ 66-67

materials for __________ 68-69

hardening by ___________ 15-17 

hardness of _______ __ 12

information concerning, inquiries for _____j. 7 

publications on _______ 7-9

malleability of ________ 12-13,18 

occurrence of, forms of_____ 18-19 

salts of _______________ 14 

tests of _____________ 15,66-69 

uses of________________ 15-18 

weight of ___________'__ 12 

See aho Tungsten deposits; 

Tungsten minerals; 

Tungsten ores; Tungsten steels ; Tungsten 

veins. 

Tungsten, Nev., scheelite from, plate

showing-. __ _ 32

Tungsten deposits, enrichment of__ 64-65

forms of ___________:___ 37-45

' geographic distribution of____36-37
INDEX. 85

Page.

Tungsten deposits, geology of 35,65-66 

prospecting for_____-_ _ 65-66 

richness of, estimation of_ 69-74, 78-79 

Sec also Tungsten ores. 

Tungsten King mine, Wash., hiibnerite from, plate showshowing.___ _ 45 

Tungsten minerals, chemical and

physical properties of_ 19-21 

. comparative value of____ __ 75 

crystals of_-____________ 20-21 

descriptions of__________ 21-35 

field tests for___________ 66-67 

materials for ________ 68-69 

view of _________ 68 

identification of__________ 9,20 

tests for __________ 66-69 

list of ________________ 19-20 

minerals associated with 39-40 

placers of___________ 44-45, 60 

plates shpwing__ __ passim, 

weathering of__________ 59-61 

See also Cuprotungstlte; Ferberi t e ; Ferritungstite ; 

Hiibnerite; Raspite; 

Scheelite; Stolzite; 

Tungstite; Wolframite. 

Tungsten ores, comparative values

of____________ 75 

. hurtful minerals in______ 74 

minimum tungsten content acceptable in _______ 75 

quality of, demanded by the

trade __________ 74-75

reduction of, modes of_____ 73-74

richness of, estimation of- 69-74, 78-79

figure showing____ 73

specific gravity of __ ____ 69-74

Tungsten steels, analyses of ___ 16-17

efficiency of ____________ 16

figure showing____ _ 16

use of _______ 15-17

Tungsten veins, classes of______ 59

depth of _________ 61-63

distribution of tungsten in__ 63-64

minerals in________ 39-40, 45-49

outcrops of_____________ 59-61

search for__________ 65-66

tenor of, relation of, to depth_ 64 65

Tungstite, gold and, association of_ 33

plates showing__________ 30, 32

occurrence and character of- 33-34, 76

U. Page. 

9

Umpleby, J. B., on tungsten deposits__ _ . _

Utah, schecllte from, plates showing____________ 30,32 

tungsten in_______ 31, 35, 43, 56

V.

Veins, tungsten in___________ 30-40

Sec also Tungsten veins. 

Virginia, tungsten in___ 36, 38, 46, 51, 54 

Vug, definition of-_____-____ 40

Washington, htibnerite from____ 47,60

hiibnerite from, plate showing_ 45

tungsten In 28,

34, 38, 47, 48, 52, 55, 60

wolframite from________ 28-29, 38

plate showing 38

Wasp mine, S. Dak., scheelite from,

plate showing _.__ 30

Weeks, P. B., on tungsten deposits- 9 

White Oaks, N. Mex., hiibnerite

from_____ ____ 76 

hvibnerite from, plate showing- 24 

Wlckard mine, Cal., scheelite from,

plate showing 52 

Winchell, A. N., on tungsten deposits_____ ___ 9 

Winnebago claim, N. Mex., ferberite

from, plate showing-- 20 

Winters, R. J., and Gray, G. J., on

tungsten veins 62 

Wolframite, composition of 22 

crystals of ____________ 21, 27 

distribution of___________ 28-29 

gold and, association of 36 

minerals resembling _____ 28 

physical features of_____ 11, 27-28 

plates showing- 24, 27, 28, 30, 38, 39, 50 

silver and, association of _ 36 

streak of :_____________ 28 

tungsten in___ _, 11-12 

veins of, outcrops of __ _ 60 

Wolframites, composition of_____ 21-22 

subdivision of_________^___ 22 

See also Wolframite; Htibnerite; Ferberite.

o