DEPARTMENT OF THE INTERIOR

UNITED STATES GEOLOGICAL SURVEY

GEORGE OT1S SMITH, DIRECTOR

.jf BULLETIN 583

\ ' ' 

COLORADO FERBERITE AND THE r* i

WOLFRAMITE SERIES A

BY

FRANK L. HESS

AND

WALDEMAR T. SCHALLER

WASHINGTON

GOVERNMENT FEINTING OFFICE 

1914

CONTENTS.

THE MINERAL RELATIONS OF FERBERiTE, by Frank L. Hess.................. 7

Geography and production............................................. 7

Characteristics of the ferberite.......................................... 8

" Geography and geology of the Boulder district........................... 8

Occurrence, vein systems, and relations................................. 9

Characteristics of the ore.............................................. 10

Minerals associated with the ferberite................................... 12

Adularia.......................................................... 12

Calcite........................................................... 12

Chalcedony....................................................... 12

Chalcopyrite...................................................... 12

Galena........................................................... 12

Gold and silver.................................................... 12

Hamlinite (?).................................................... 14

Hematite (specular)................................................ 15

Limonite........................................................ 16

Magnetite........................................................ 17

Molybdenite..................................................... 17

Opal............................................................. 17

Pyrite............................................................ 17

Quartz.......................................................... 17

Scheelite............ r ............................................ -17

Sphalerite... r ................................................... 17

Sylvanite........................................................ 17

Spectroscopic examination.............................................. -18

Crystallized ferberite.................................................. 19

Composition of ferberite and other members of the wolframite series...... 19

Definition of ferberite and other members of the wolframite series........ 37

The excess of ferrous oxide and manganous oxide....................... 38

CRYSTALLOGRAPHY OF FERBERITE FROM BOULDER COUNTY, COLO., by Waldemar T. Schaller...................................................... 40

Previous publications................................................. 40

General characters of the crystals....................................... 40

Mode of occurrence............................................... 40

Size................-....-....-....---.---.----------------------- 41

Color and cleavage............................. ................,. 42

The measured crystals by localities.................................... 42

Axial elements. ..................-.--.---.---.-.--.- -- ---- ----- 43

4 Calculation of values..........:................................... 43

Comparison of values.....................-....-...-.------.------. " 45

Forms and angles. ..........,.........----------------------- --- - --- 46

New forms. .......................--- - --- - --------- - - - 47

Forms previously described ..........................----..------- - 52

Common forms. ....................---..--...-------------- -- -- 52

Rare forms. ........................-.- ----- - - - 53

3
CONTENTS.

CRYSTALLOGRAPHY OF PERBERITE PROM BOULDER COUNTY, COLO. Continued.

Discussion of the prism zone............................................ 55

Habit................................................................ 56

Combinations......................................................... 60

Twinning............................................................ 62

Description of measured crystals........................................ 65

Form system of the wolframite group................................... 69

Critical study of forms............................................ 69

Forms and coordinate angles........................................ 71

Combinations observed on the wolframite group...................... 73

Bibliography......................................................... 74

ILLUSTRATIONS.

PLATE I. A, Fefberite inclosing finely brecciated granite, from Rogers tract, 

Nederland, Colo.; S, "Peanut ore," ferberite inclosing finely 

brecciated pegmatite, from the Conger mine, Nederland, Colo.... 10 

II. Brecciated granite and pegmatite cemented by ferberite, from Town

Lot mine, Nederland, Colo...................................... 11

III. Brecciated ferberite vein, showing crystals formed since brecciation,

from Conger mine, Nederland, Colo............................. 12

IV. A, Cut and polished crystal of brown ferberite from Winnebago 

claim, near Rollinsville, Colo.; B, Brecciated ferberite vein from 

the Conger mine, Nederland, Colo.............................. 13

V. Vug in a ferberite vein nearly filled by scheelite, the cavity then

remaining being filled by quartz................................ 14

VI. A and B, Thin sections of ore showing hamlinite (?), from Eagle

Rock mine, 8 miles west of Boulder, Colo....................... 15

VII. A, Wedge-shaped ferberite crystals from the Lone Tree mine, Nederland, Colo.; B, Wedge-shaped ferberite crystals from the Hoosier 

mine, Nederland, Colo.......................................... 18

VIII. A; Crystallized ferberite from the "Crow patent," Nederland, Colo.; 

B, Crystallized ferberite from the Georgia A. mine, Nederland, 

Colo............................................................ 19

I.. Crystallized ferberite with elongated rhombic crystal faces, from the

Nugget mine, Gilpin County, Colo.............................. 20

X. Crystallized ferberite with elongated rhombic crystal faces, from the

Nugget mine, Gilpin County, Colo.: A, Edge view; B, Side view.. 21

XI. Ferberite with rhombic crystal faces; from the Nugget mine, Gilpin

County, Colo.................................................. 22

XII. Very fine specimen of ferberite with rhombic crystal faces, from the

Nugget mine, Gilpin County, Colo.............................. 23

XIII. A, Section of hiibnerite from the Dragoon Mountains, Ariz., showing 

zonal structures; B, Photomicrograph of granite from the Whetstone Mountains, Ariz., showing wolframite with warty protuberances of scheelite along its edges................................ 30

XIV. Section of wolframite from Irish Creek, Va., showing interstitial

scheelite...................................................... 31
ILLUSTEATIONS. ' 5

Page.'

FIGURE 1. A, Orthographic projection of crystals "with similar combinations, in 

parallel grouping, joined by the a (100) faces; B, Same with dissimilar combinations. .....'. .................................... 41

2. Superposed crystals, joined by the c (001) faces.................... 41

3. Long, narrow, wedge-shaped crystal of habit 1..................... 57

4. Short, prismatic, somewhat flattened crystal of habit 2............ 57

5. Tabular crystal of habit 3......................................... 57

6. Cubic crystal of habit 4.......................................... 57

7. Rhombic crystal of habit 5....................................'.. 57"

8. Cleavage pieces of crystals......................'.................. 58

9. Striations on wedge-shaped crystals of habit 1...................... 59

10. Crystal No. 4, wedge-shaped habit.-.............................. 59

11. Peculiar shape of wedge-shaped habit caused by cleavage.......... 59

12. Crystal of short prismatic, somewhat flattened habit.............. 59

13. Crystal of rhombic habit, nearly equidimensional.................. 59

14. Contact twin on (023)............................................ 63

15. Contact twin on (023)...........................................- 63

16. Line of contact of two contact twins.............................. 63

17. Penetration twin on (023)........................................ 64

18. Penetration twin on (023)........................................ 64

19. Crystal No. 29.................................................. 64

20. Crystal No. 32.................................................. 64

21. Crystal No. 33.................................................. 64

22. Crystal No. 5................................................... 66

23. Crystal No. 6................................................... 66

24. Crystal No. 9................................................... 66

25. Crystal No. 13.................................................. 66

26. Crystal No. 16.....................:............:............... 67

27. Crystal No. 17.................................................. 67

28. Crystal No. 18.................................................. 67

29. Crystal No. 19.................................................. ' 67

30. Crystal No. 20.................................................. 68

31. Crystal No. 36.................................................. 68

32. Cubic crystal................................................... 68

33. Rhombic crystal..... ........................................... 68

34. Crystal No. 26........................'................. 1........ 68

35. Gnomonic projection of forms of the wolframite group............. 70

COLORADO FERBERITE AND THE WOLFRAMITE SERIES.

By FRANK L. HESS and WALDEMAR T. SCHA'LLER.

THE MINERAL RELATIONS OF FERBERITE.

By FRANK L. HESS.

GEOGRAPHY AND PRODUCTION.

Ferberite, as ordinarily defined, is that mineral of the wolframite 

series which is composed wholly or almost wholly of iron tungstate 

and which, like other wolframites, crystallizes in the monoclinic system. It is comparatively rare and in most places wherefound it seems 

to occur in small quantities only. It occurs in largest quantity in 

Colorado, about 25 miles northwest of Denver, mainly in Boulder 

County, though the deposits extend a short distance southward 

beyond the county line into the north end of Gilpin County. From 

this area, which has a southwest-northeast length of about 12 miles 

and a width of 6 to 7 miles, an equivalent of probably 7,300 short 

tons of concentrates carrying 60 per cent WO3 had been mined from 

1901, when exploitation of the tungsten veins began, to the close 

of 1912.

The relative importance of the Boulder tungsten field, as the area 

is generally known, is indicated by the statistics of the production 

of tungsten ore in 1910, in which year the output of the field was 

1,221 tons. In the same year the output of Queensland was 1,145 

tons; Portugal, 1,132 tons; Argentina, 1,061 tons; and the world's 

production was probably about 7,500 tons, the remainder being 

smaller lots from many countries.1 The tungsten-bearing mineral 

produced from the three countries named was wolframite, and no 

other country produced any considerable quantity of f erberite.

»F<n details see Hess, F. L., Tungsten: U. S. Geol. Survey Mineral Kesources, 1910, pt. 1, p. 734, 1911. 

Since the above paragraph was written the world's statistics for 1911 and 1912 have become available, and 

these show that Burma has outstripped all other producers, its output of wolframite being equivalent to 

2,096 short tons of ore carrying 60 per cent WOg. (See U. 3. Geol. Survey Mineral Kesources, 1911 and 1912.)

7
8 COLORADO FERBERITE AND THE WOLFRAMITE SERIES. 

CHARACTERISTICS OF THE FERBERITE.

Ferberite occurs in the Boulder County field not only in large 

quantity, but in places in clean, beautifully developed crystals, and 

very commonly in small crystals coated with foreign material. 

The ferberite found over most of the field is jet black, but in a few 

places it is brown. It is opaque even in thin sections prepared for 

microscopic examination, and the clean crystals and cleavage faces 

are generally lustrous black.

The ferberite of Boulder County is very resistant to weathering 

and forms placers which have been successfully worked. The ferberite of the Black Hills (see analysis 81, pp. 32-33) decays, leaving 

a skeleton of hydrous iron oxide, and wolframites that are close to 

ferberite in composition decay similarly, but no alteration has been 

noted in the "ferberite of the Boulder field, although it is in many 

places coated and discolored by hydrous iron oxide and other minerals.

The other physical characteristics accord fairly well with those 

given by Dana* for the wolframites. The cleavage along 6 is perfect, and in some specimens a parting is shown parallel to a, but I 

have not noticed the parting parallel to t (102) mentioned by Dana. 

The fracture is uneven and the mineral is brittle. Its streak and 

powder are dark brown nearly black and its hardness is about 5. 

Its specific gravity, as determined on selected crystals, is 7.499.

A splinter of pure material fuses to a globule which has a crystalline 

surface and is not magnetic. The brown mineral from the Rogers 

tract is almost infusible before the blowpipe, and is strongly magnetic after heating.

Although ferberite is not very soluble in acids, if it is finely powdered and boiled a few minutes with concentrated hydrochloric acid 

it gives a solution which, on the addition of zinc, readily shows a 

characteristic blue color, followed by the almost equally characteristic violet and brown.

GEOGRAPHY AND GEOLOGY OF THE BOULDER

DISTRICT.

Nederland, the commercial town of the Boulder tungsten field, 

lies 2 miles east of Cardinal station, on the Denver, Boulder & Western Railroad, and 4 miles north of Rollinsville, on the Denver, 

Northwestern & Pacific Railway.

The ferberite-bearing area lies on an elevated plateau, above 

which, on the west, rise massive and imposing peaks. The altitude 

at Nederland is 8,237 feet. On the east an abrupt scarp descends 

from the plateau to the Great Plains. Streams draining the plateau 

have cut deep canyons extending back from the scarp to distances 

determined by the abrading power of the streams.

i Dana, E. S., System of mineralogy, 6th ed., p. 983,1909.
OCCURRENCE, VEIN SYSTEMS, AND RELATIONS. 9

Biotite-hornblende granite, in some places gneissoid, granitic 

gneiss, and quartz-mica schist form the country rocks. The gneiss 

and schist are older than the granite, and all three are of pre-Cambrian age and are cut by later dikes that range in composition from 

limburgite to granite pegmatite.

Dynamic metamorphism has in places made the granite, gneiss, 

and schist difficult to differentiate. Some of the dikes are also more 

or less squeezed. The gneiss is believed by R. D. George * and Edson 

S. Bastin 2 to be of sedimentary origin. The pegmatites show only 

a little crushing and carry few metallic minerals.

OCCURRENCE, VEIN SYSTEMS, AND RELATIONS.

The ferberite occurs in a group of veins which in general extend 

from southwest to northeast, though individual veins strike toward 

nearly every point of the compass.

On the northwest and southwest sides of the tungsten-bearing area 

are gold and silver bearing veins having the same general trend as the 

tungsten veins. The veins carrying the precious metals are a continuation of the gold-bearing belt of Clear Creek and Gilpin counties. 3

Two types of veins carry the gold and silver those in which the 

minerals are mostly sulphides and those in which the gold occurs as a 

telluride.4 The sulphidic veins are in general quartz veins carrying 

gold and silver bearing sulphides, such as pyrite, galena, chalcopyrite, 

and zinc blende. Silver predominates. The telluridie veins 5 occur 

in sheeted zones and contain only a little quartz. They carry gold 

mostly in a telluride, which is probably sylvanite, and the gold predominates over the silver. Pyrite, molybdenite, a vanadium mineral 

allied to roscoelite, barite, adularia, and chalcedony accompany the 

telluride. The veins are thin and commonly frozen to the walls.

The ferberite veins are more or less connected with the gold veins, 

as might be expected from the general grouping, and their connection 

with the telluridic veins seems closer than with the sulphidic veins. 

Specimens from Magnolia, at the southeastern edge of the field, 

showed both gold telluride and ferberite, but it could not be determined which was the older. George reports a like specimen in which 

the telluride was evidently the older mineral. 8 He also reports the 

occurrence of the two minerals in the Wheelmen Tunnel, in Boulder 

Canyon, 0 and at Sunshine, on the northern "'dge of the field. Aspeci1 George, R. D., The main tungsten area of Boulder County, Colo.: Colorado Geol. Survey First Kept., 

pp. 19-20, 1909.

* Oral statement.

8 Lindgren, Waldemar, Some gold and tungsten deposits of Boulder County, Colo.: Econ. Geology, vol. 

2, p. 453, 1907.

«Idem, pp. 45&-4S7.

& Idem, pp. 457-459. '

8 George, R. D., op. cit., p. 76.
10 COLORADO FERBERITE AND THE WOLFRAMITE SERIES.

men from Ward, still farther north and beyond the territory which up 

to this time has been productive, shows a wolframite which is probably not f erberite and which occurs in long, slender crystals of a habit 

totally different from that of the ferberite of the main tungsten area. 

Embedded with this mineral in white quartz are pyrite and chalcopyrite, apparently of the same general age, though the chalcopyrite is of 

later deposition, as it is pierced by the wolframite. The ore is said to 

carry both gold and silver. Although the data at hand are not very 

extensive, it seems probable that the connection between the three 

classes of veins may be fairly close and that there may not be a great 

difference in the ages of the several types. The manganese content of 

the tungsten mineral seems to increase somewhat progressively across 

the field from the Gilpin County line to Ward that is, from south to 

north. A few miles south of the tungsten field in Gilpin County pitchblende has been found in considerable quantity in close connection with 

gold and silver bearing veins, which lie in the same mineral belt. 

Forbes Rickard has recently noted 1 a close relationship between the 

ferberite veins of Boulder County and the pitchblende veins of Gilpin 

County.

The ferberite veins much resemble those carrying gold telluride. 

They occur in sheeted or crushed zones and are reticulated, the individual veins ranging from a small fraction of an inch to several inches 

in thickness, while the ore-bearing body may reach a width of 14 feet, 

as in the Philadelphia mine of the Wolf Tongue Mining Co. The veins 

cut granite, gneiss, and pegmatite, and though the ore may extend 

from the granite into the gneiss it may be cut off at the contact, its 

continuity depending on local conditions, but there are only a few 

productive veins in the gneiss.

CHARACTERISTICS OF THE ORE.

The amount and character of gangue in the veins differ greatly in 

different parts of the field. Quartz, the universal vein mineral, occurs 

in much less quantity in the ferberite veins than in most veins. Only 

a very little visibly crystallized quartz in the ferberite veins has come 

to my attention. There is, however, in most if not in all of the veins of 

the northeastern part of the field, and in many of the wider veins of 

the southwestern part of the field, a very fine grained gray or brown 

quartz, known as "bone," which has a fracture much like that of 

chalcedony and which is largely a replacement of the country rock. 

The ferberite in the northeastern half of the field appears to be less 

well crystallized than in the southwestern half. . It occurs in some of 

the veins in minute particles mixed with quartz (see PI. VI, p. 15), so 

that in many places the ore is difficult to concentrate, although the

1 Pitchblende from Quartz Hill, Gilpin County, Colo.: Min. and Sci. Press, June 7,1913, p. 852.
A. FERBERITE INCLOSING FINELY BRECCIATED GRANITE. 

From Rogers tract, Neclerland, Colo. Natural size.

B. "PEANUT ORE," FERBERITE INCLOSING FINELY BRECCIATED PEGMATITE. 

From the Conger mine, Nederland, Colo. Natural size.
U. S. GEOLOGICAL SURVEY ULLETJN 583 PLATE II

BRECCIATED GRANITE AND PEGMATITE CEMENTED BY FERBERITE. 

Town Lot mine, Nederland, Colo. Natural size.
CHARACTERISTICS OF THE ORE. 11

total percentage of W03 may be as high as or higher than that in ores 

which are easily and profitably worked.

In the southwestern part of the field the narrower individual veins 

are made up almost wholly of ferberite, which has grown from both 

sides of the crevices and forms combs of small crystals that coalesce 

at their bases. The combs are of fairly uniform thickness, so*that 

although in the narrower crevices they may have met and grown 

together, in the wider cracks they form bristling crusts of crystals on 

each side. In places these crystals are clean and bright but generally 

very small, from one to three thirty-seconds of an inch (1 to 2 millimeters) across. Most of the crystals are covered with a coating of 

impure chalcedony, which in some specimens is mixed with opal and 

in others contains much iron. The coating generally includes small 

crystals of ferberite, which are of course of a later generation than 

those on the walls. Some vugs 3 or 4 inches across are entirely filled 

with such a mixture.

On the Nugget claim, 3£ miles southeast of Nederland, the crusts of 

nearly pure ferberite reach a thickness of more than an inch, and this 

claim has produced the finest crystallized specimens of ferberite yet 

found. In the veins of this claim, as in the others, most of the.crystalline aggregates are covered with a siliceous mixture, which here 

carries much brown iron oxide. The veins cut a moderately coarse 

grained pegmatite and have so far produced only a small quantity of 

ore. The Winnebago, an adjoining claim, has produced some small 

specimens of crystallized ferberite from similar veins.

In places the country rock instead of being sheeted is crushed into 

smaller, more nearly equidimensional fragments, which may not be 

over one-eighth inch (3 millimeters) in diameter. Ore in which fragments of rock no larger than half an inch (13 millimeters) across 

are embedded in ferberite is popularly known as "peanut" ore, from 

its.resemblance to peanut candy. (See PI. I.) The fragments of the 

breccia vary greatly in size (PL II), and where the fragments are larger 

the breccia is characterized by vugs lined with ferberite crystals. 

Both finely and coarsely brecciated ore is. typical of the veins of the 

district. Many of the veins have been opened, several times, so that 

the ferberite itself is brecciated. (See Pis. .Ill and IV, B.)

In places the ferberite carries considerable manganese and grades 

into wolframite. The mineral from Gordon Gulch carries almost 6 per 

cent MnO (analysis 58, pp. 30-31) and wolframite occurs on the north 

side of the field at Ward (analysis 49). The only other tungsten 

mineral so far identified in the field is scheelite, which occurs in small 

quantity as a thin coating of octahedral nearly white crystals about 

one thirty-second inch (1 millimeter) in thickness, over a film of ferberite covering the walls of crevices in the Sugar Loaf district in the 

northern-central part of the area. Vugs in ore from the Frigid Mining
12 COLORADO FERBERITE AND THE WOLFRAMITE SERIES.

Co.'s claim at Crisman are lined with clear brownish and colorless 

scheelite crystals, the largest three thirty-seconds of an inch (2 millimeters) thick. Vugs in ore from the Rogers tract, near the center of 

the area, are lined with reddish-brown scheelite, which also occurs 

through the quartz in small quantity. Some of the vugs are of almost 

microscopic size. (See PL V.) As seems to be usual in tungsten 

deposits, the scheelite formed later than the mineral of the wolframite 

series, but it is nojb a secondary mineral. In cleaning certain ferberite 

crystals with, hydrofluoric acid deep pits with rather regular outlines 

are made, accompanied by the formation of yellow tungsten trioxide, 

and it seems possible that the pitting may be due to the removal of 

scheelite.

MINERALS ASSOCIATED WITH THE FERBERITE.

Associated minerals, other than quartz, are few and scarce in the 

ferberite veins of the main part of the field. Near the gold-silver 

bearing areas there is of course a mixture of the minerals of the several 

vein groups.

The following minerals accompany ferberite in the veins:

Adularia. Adularia forms a coating one-sixteenth of an inch (2 

millimeters) thick on the walls of the Black Hawk No. 2 vein, 1£ 

miles south of Nederland. It is beneath most of the ferberite, but 

was probably- deposited with the first of the ferberite. Adularia in 

microscopic grains is found in many of the veins.

Calcite. The gangue in the Conger mine carries microscopic particles of a carbonate, which is probably calcite.

Chalcedony. Chalcedony mixed with more or less opal and hydrous 

iron oxide coats crystals from many of the veins.

Chalcopyrite. Chalcopyrite occurs at Ward in veins carrying some 

wolframite, which seems to approach ferberite in composition, though 

no analysis of the mineral is at hand.

Galena. George 1 reports the occurrence of galena and sphalerite 

in veins with ferberite near Magnolia. The galena is said to occur 

generally in minute cubes but in considerable quantity.

Gold and silver. Gold and silver are reported to occur in some of 

the ferberite veins other than those in which sylvanite is present. 

In the ore seen which is said to be gold-bearing small quantities of 

sulphides are present and the gold is probably associated with the 

pyrite. Hills 2 states that eight assays of concentrates gave an 

average of 0.01 ounce of gold to the ton.

Greenawalt 3 gives three analyses of concentrates which carried 

silver in quantities of 1.2, 2.4, and 3.1 ounces to the ton. The speci1 George, R. D., The main tungsten area of Boulder County, Colo.: Colorado Geol. Survey First Kept., 

p.-75,1909.

»Hills, V. G., Tungsten mining and milling: Colorado Sci. Soc. Proc., vol 9, p. 150,1909.

8 Greenawalt, W. E., The tungsten deposits of Boulder County, Colo.: Eng. and Min. Jour., vol. 83, p. 

951,1907.
U. S. GEOLOGICAL SURVEY 

< - * -L..

BRECCIATED FERBERITE VEIN, 

s crystals formed since brecclation. Conger mine, Nederland, Co
U. S. GEOLOGICAL SURVEY BULLETIN 583 PLATE IV

A. CUT AND POLISHED CRYSTAL OF BROWN FERBERITE.

From Winnebago claim near Rollinsville, Colo. Shows spongy structure of the ferberite, the pores of which 

are filled with hydrous iron oxide. X 78.

S. BRECCIATED FERBERITE VEIN.

From the Conger mine, Nederland, Colo. Both the black and the gray edging it are ferberite, the difference in color being due to the orientation of the crystals. Natural size.
CHAKACTEEISTICS OF THE ORE. 13

mens came respectively from Beaver Creek, Nederland, and Gordon 

Gulch. Tomblin x states 'that in the Logan.mine at Crisman free gold 

is sometimes found with ferberite.

The occurrence of small quantities of gold and silver in tungsten 

veins is fairly common, but in many if not most veins the precious 

metals, though of the same general period of vein formation, are 

probably of later deposition than the wolframite.

Silver seems to occur in greater quantity with the wolframites than 

does gold, and gold in greater proportional quantity with scheelite, 

but this can not be stated as an invariable rule.

Hiibnerite is found near Pony, Mont., in quartz veins which have 

been worked for silver; in veins prospected for silver but not rich 

enough to work near Ellsworth, Mammoth district, Nye County, 

Nev. (the name htibnerite was given by Riotte to the mineral from 

this place); at Butte, Mont.,2 on the 300-foot level of the Gagnon 

mine, where htibnerite" formed an ore shoot of argentiferous material;" 

in the Birdie mine 4 miles east of Butte (of very light brownish-yellow 

color); 3 with silver minerals in the Combination mine, Philipsburg, 

Mont.; 4 in the mines of Silverton, Colo.5 (wolframite also); and 

Tonopah, Nev.6 Wolframite occurs with silver ore hi the Tip Top 

mine, Tip Top district, near Columbia) Ariz.; in a prospect of A. C. 

Young's at Old Hachita, N.Mex.; 7 in the Victorio district, N.Mex.; 8 

hi the Sonoma Range, 15 miles south of Golconda, Nev.; at Silver 

Mines, 10 miles southeast of Ironton, Mo.; 9 and on the Silver Comet 

and other claims southwest of Pioche, Nev. Wolframites are also 

found with deposits carrying more gold than silver in the South 

Homestake mine, White Oaks,N.Mex.; 10 gold quartz veins on Sheep 

Creek near Salmo, British Columbia;" and gold mines of Lead, S. Dak.; 

and at Cave Creek, Ariz., auriferous pyrite occurs with ferberite.

1 Tomblin, M. B., Tungsten; history, occurrence, uses: Facts concerning tungsten mining In world's 

greatest Qeld, Boulder County, Colo.: Boulder County Metal Mining Association Bull. No. 3,1912.

2\Veed, W. H., Geology and ore deposits of the Butte district,Mont.: U. S. Geol. Survey Prof. Paper74, 

p. 80,1912. See also, Pearce, Richard, The association of minerals in the Gagnon vein, Butto City, Mont.: 

Am. Inst. Min. Eng. Trans., vol. 16, p. 64,1888.

8 Tomek, F., Tungsten in Montana: Min. World, vol. 28, p. 68,1908.

<Goodale,C.W.,andAkers,W. A. .Concentratioffbeforeamalgamation for low-grade partially decomposed 

silver ores, with notes on the geology of the Flint Creek mining district: Am. Inst. Min. Eng. Trans., vol. 

18, p. 248,1890.

B Ransome, F. L., A report on the economic geology of the Silverton quadrangle, Colo.: II. S. Geol. Survey 

Bull. 182, pp. 86-87, 256, 1901.

6 Eakle, A. S., The minerals of Tonopah, Nov.: California Univ. Dept. Geology Bull., vol. 7,1912, p. 18. 

Prof. Eakle calls the mineral wolframite, but states "some of them [the crystals] are exceedingly thin and 

almost transparent, with a deep-red color." This corresponds with a specimen in my possession and seems 

to indicate htibnerite rather than wolframite.

7 Lindgren, Waldemar, and others, The ore deposits of New Mexico: U. S. Geol. Survey Prof. Paper 68, 

p. 336,1910.

8 Idem, p. 292.

»Haworth, Erasmus, A contribution to the Archean geology of Missouri: Am. Geologist, vol. l,pp. 294- 

295,1888.

10 Graton, L. C., U. S. Geol. Survey Prof. Paper 68, p. 180,1910. See analyses 4 and 16, p. 24. 

" Walker, T. L., The occurrence of tungsten ores in Canada: Canadian Min. Inst. Jour., vol. 11, pp. 

367-371,1908; Report on the tungsten ores of Canada: Canada Dept. Mines, Mines Branch, p. 37,1909,
14 COLORADO FERBERITE AND THE WOLFRAMITE SERIES.

In 1907 a lot of wolframite ore, weighing 1.1 long tons, from Ravensthorpe, Western Australia, carried 66.2 per cent W03 and yielded 5.3 

ounces of gold.1

Examples might be multiplied but would add little weight. The importance of those given lies in their bearing on the genesis of tungsten, 

gold, and silver ores. In many places tungsten ores are closely connected with pegmatites or lie in the pegmatites themselves and are 

probably in nearly all places close to a magmatic source. The gold 

and silver found in the deposits must be likewise near their place of 

origin. Of course, it is not to be argued that the absence of tungsten 

minerals implies that the gold and silver may not be near a magmatic 

source, but gold and silver appear to accompany siliceous.solutions 

much farther from their igneous source than do tungsten minerals. 

It seems probable that the tungsten minerals may be deposited from 

the hotter waters emanating from magmas, and silver and gold from 

the solutions after they have somewhat cooled.

Hamlinile (?).-^-In sections cut for microscopic study from a specimen obtained at the Eagle Rock name many small, very light green 

fragments of a uniaxial, optically positive mineral were found. As 

determined by E. S. Larsen, its indexes of refraction are &>= 1.620± 

0.003, £=1.630±0.003. Its birefringence is 0.010, but some basal 

sections show anomalous birefringence as though divided into segments. It has a perfect basal cleavage and shows a slight zonal 

growth. The particles show a tendency toward square sections, and 

the optical properties suggest that the mineral belongs to the alunitehinsdalite series. Although very small, the particles are numerous, 

forming perhaps 10 to 25 per cent of the bulk of this particular ore. 

(See PL VI.) The gangue is ".horny" quartz through which are distributed particles of ferberite and certain other particles which are 

attracted by a magnet, probably magnetite, both of which occur in. 

grains almost as small as the unknown mineral. An attempt was made 

to separate the mineral from its gangue by grinding it very fine and 

passing the powder through-a Thoulet solution of 2.8 specific gravity, 

but the material was too much mixed with quartz to show sufficient 

improvement for analytical purposes. The fact that with the attached quartz it sank through the liquid indicates that its specific 

gravity is above 2.8, but it is probably not over 3. A partial analysis 

by George Steiger, in the chemical laboratory of the United States 

Geological Survey, showed the presence of aluminum, 2 per cent 

strontium, a very little sulphur as a sulphate, and 3.6 per cent phosphorus pentoxide. The only heavy metals found were tungsten, 

iron, manganese, and a trace of titanium. Fluorine and chlorine 

were absent. There was only a questionable trace of calcium and a 

very small quantity of magnesium.

1 Simpson, E. S., and Gibson, C. G., The distribution and occurrence of the baser metals in Western 

Australia: Western Australia GeoL Survey Bull. 30, pp. 115-117,1907.
U. S. GFOLOGICAL SURV 

VUG IN FERBERITE VEIN NEARLY FILLED BY SCHEELITE, THE CAVITY THEN 

The black is ferberite, the gray mottled area is scheelite, and the nea
BULLETIN 533 PLATE VI

«*_,«

:** /

: ..*</" v-' ri.

f ;. *1ijjgte

 ' cA r ^E§ * , %*<!

i;C|; ,'f5 «- * ^|.

^ \ '', ' "'^-u^ ;'yvX'

'.»» < '' 'v'-^j'.i * -r» »»*«-. 

JA«f-^^* ^' *

]i.

THIN SECTIONS OF ORE SHOWING HAMLINITE.

From Eagle Rock Mine, 8 miles west of Boulder, Colo. Groundmass, quartz. Mineral with high relief, 

hamlinlte (?) Black mineral, ferberite. X 380.
CHARACTERISTICS OF THE ORE. 15

The mineral seems to be close to hamlinite, for which the formula, 

as recalculated by. Prior, 1 is 2Sr0.3Al203 .2P205 .7H20, but as a little 

sulphur is present it probably belongs in the series between hamlinite 

and svanbergite .(2Sr0.3Al203 .P205 .2S03 .6H20). Another mineral 

of the same group, hinsdalite (2Pb0.3Al203 .P205 .2S03 .6H20), was 

discovered in 1910 by Larsen 2 as a vein mineral in the Golden Fleece 

mine, near Lake City, Colo.

The same mineral has been found in sections from other parts of the 

Boulder field, though not in such large quantity as in the Eagle Rock 

specimen. Sections of ' 'hornstone " ore from other places have shown 

none of it. However, phosphorus in small quantity is nearly if not 

quite a universal component of the Boulder County tungsten ores.

Hugh F. Watts, who has assayed thousands of samples of ferberite 

ores and concentrates coming from aU parts of the Boulder field, 

states that whenever he has tested for it he has found phosphorus 

present.3 In one test on a composite of seven ores the phosphorus 

present amounted to 0.038 per cent. Hills 4 notes from 0.01 to 0.02 

per cent phosphorus in eight out of nine analyses of concentrates 

and a trace in the other. Greenawalt 5 notes 0.05 per cent in a 

concentrate from Gordon Gulch. No apatite or other phosphate 

except the hamlinite (?) has been found, and it seems reasonable 

to suppose a very wide distribution of the hamlinite (?). The mineral apparently occurs only in the quartz gangue, and if the ore 

is finely ground before separation very little will be left hi the concentrates, for its specific gravity (more than 2.8 and probably not 

higher than 3) is so low that it would readily pass into the tailings.

1 hope to make further investigation of this mineral.

Hematite (specular). At the south end of the Black Hawk No. 1 

vein, If miles south of Nederland, a short vein which is nowhere more 

than a few inches thick, the ferberite gives way to specular hematite. 

This mineral is also found in.small quantity in some other veins, and 

what is known as the May vein, a short distance east of the Black 

Hawk No. 1 vein, is a series of anastomosing veinlets made up of specular hematite, which is said to be accompanied by a little tungsten, 

though none could be found in specimens collected. Hills 4 gives 

an analysis of ferberite concentrates from "the east side of the district," in which the content of FeO exceeds that of W03 , and another 

in which the quantity of FeO is only a little less than that of W03 . 

The analyses follow.

i Prior, G. T., Hamlinite, plumbogummite (hitchcockite), beudantite, and svanbergite, as members of 

anatural group of minerals: Mineralog. Mag., vol. 12, p. 253,1900.

2 Larsen, E. S., and Schafler, W. T., Hinsdalite, a new mineral: Am. Jour. Sci., 4th ser., vol. 32, p. 251, 

1911.

8 Private communication. <

4 Hills, V. G., Tungsten mining and milling: Colorado Sci. Soc. Proc., vol. 9, pi 149,1909.

6 Greenawalt, W. E., The tungsten deposits of Boulder County, Colo.: Eng. and Min. Jour., vol. 83, p. 951, 

1907.
16 COLORADO FERBERITE AND THE WOLFRAMITE SERIES. 

Analyses of tungsten concentrates treated at the Clarasdorf mill, near Boulder, Colo.

' -

Sulphur. ........................................................................... 4 ...

Silicon dioxide. . ............. ....>.............................;........................

1

38.46

39.31

.51

.27

3.10

.01

18.61

2

38.69

34.01

2.59

1.38

2.67

.01

22.13

The first analysis indicates a wolframite of the composition MnW04 , 

26 per cent; FeW04 , 74 per cent a composition close to that of the 

Gordon Gulch wolframite (analysis No. 58, p. 31). After satisfying 

the MnO present only 8.8 of the 39.31 per cent FeO given is required 

to combine with the W03 . The second analysis indicates a wolframite of the composition MnW04 , 22.7 per cent; FeW04 , 77.3 per cent. 

This composition requires for combination with W03 only 8.7 of the 

34.01 per cent FeO. The form in which the iron is present is unknown, 

but the possibility that it maybe specular hematite is at once suggested 

by knowledge of the occurrences mentioned. The sulphur shown in 

the analyses indicates, of course, that a small quantity of iron is present as pyrite.

Occurrences of specular hematite with wolframites are not unknown. At South Crofty mine, Cornwall, "the presence of specular 

iron has caused trouble in obtaining a high-class wolfram concentrate."1

It seems probable that deeper workings on the Rogers tract may 

show specular hematite, to the decomposition of which may be due 

the brown color of much of the ferberite from that tract.

Limonite. Limonite, under which term are here included all hydrous oxides of iron, occurs in many veins, and nearly all the ore 

on the Rogers tract, about 2 miles northeast of Nederland, is stained 

brown with it. The crystals of ferberite are not only brown on the 

outside, but when broken show brown sections. (See p. 38 and PI. 

IV, A, p. 13.) The origin of the limonite and its relationship to the 

ferberite are unknown, but in part at least it is possibly altered from 

specular hematite, as already stated. Iron-bearing carbonates occur 

in some tungsten deposits, notably the scheelite deposits of Atolia, 

Cal. Carbonates decompose much more easily than specular hematite, and one may have been originally inclosed in the ferberite of 

the Rogers tract and some other places.

Magnetite. Magnetite is recorded by George 2 as occurring with 

the ferberite. Magnetite seems to be a probable associate of ferberite,

i Anon., Cornwall (editorial): Min. Mag., London, vol. 8, p. 165,1913.

s George, R. D., The main tungsten area of Boulder County, Colo.: Colorado Geol. Survey First Bept., 

p. 75, 1909,
CHARACTERISTICS OF THE ORE. 17

but in several specimens of powdered ferberite examined I have not 

been able to separate it with a horseshoe magnet nor to find it by 

microscopic examination with reflected light in polished and etched 

specimens from the Western Star and Nugget claims. In the ore 

from the Eagle Rock mine, however, a small quantity of magnetic 

material which is probably magnetite was found.

Molybdenite. George 1 and Lindgren 2 report, though Lindgren 

doubtfully, that molybdenite occurs with the ferberite in Boulder 

County. I have not seen this association. Molybdenite is a common associate of wolframite in Queensland 3 and is also found with it 

in Saxony 4 and England,5 but the association is rare in this country, 

though molybdenite occurs with wolframite and tourmaline on the 

Black Horse claims, 10 miles southeast of Daisy, Stevens County, 

Wash., and in small quantity with ferberite at Cave Creek, Ariz.

Opal. Opal mixed with chalcedony and a little limonite forms a 

thin opaque yellowish-gray coating on ferberite crystals in the Black 

Hawk No. 1 vein, 1£ miles south of Nederland, and is probably a 

constituent of the siliceous coating on the ferberite from other mines.

Pyrite. Pyrite is rare, except where the ferberite veins approach 

the gold and silver veins, though here and there a little may be found. 

At one place in the Conger mine a vein of pyrite 2 inches thick cut 

across the ferberite veins. Iron sulphide in quantities reaching 3.25 

per cent 8 is indicated by analyses of concentrates from a number of 

places, as noted under hematite.

Quartz.- Quartz occurs in all veins in comparatively small quantity. 

In most places it is so finely granular that it has a fracture like chalcedony. Very little of it shows crystal form.

Scheelite. For discussion of the occurrence of scheelite see pages 

11-12.

Sphalerite. Sphalerite is noted by George (see Galena, p. 12), and 

Moses 7 states that he found small yellow crystals upon ferberite 

specimens from the Boulder field.

Sylvanite. As has been noted, sylvanite occurs with ferberite at 

Magnolia. George 8 also notes this association in the vein exposed 

by the Wheelmen Tunnel in the lower part of the canyon of Boulder 

Creek and in a mine near Sunshine.

1 George, R. D., The main tungsten area of Boulder County, Colo.: Colorado Geol. Survey First Bept., 

p. 75,1909.

2 Econ. Geology, vol. 2, p. 461,1907.

'Cameron, W. E., Wolfram and molybdenite mining in Queensland: Queensland Geol. Survey Kept. 

188,13 pp., 1904.

< Beck, R., Uber ein kiirzlich aufgeschlossenes Wolframerzgangfeld und einige andere neue Aufschliisse 

in sachsischen Wolframerzgruben: Zeitschr. prakt. Geologie, vol. 15, pp. 38,40,1907.

o Finlayson, A. M. "The ore-bearing pegmatites of Carrock Fell and the genetic significance of tungsten 

ores: Geol. Mag., vol. 7, pp. 19-28,1910.

«Hills, V. G., Tungsten mining and milling: Colorado Sci. Soc. Proc., vol. 9, p. 149,1909.

7 Moses, A. J., The crystallization of luzonite and other crystallographic studies: Am. Jour. Sci., 4th ser., 

vol. 20, p. 282,1905.

8 Op. cit., p. 76.

35659° Bull. 583 14 2
18 COLORADO FERBERITE AND THE WOLFRAMITE SERIES. 

SPECTROSCOPIC EXAMINATION OF THE FERBERITE.

Scandium, 1 columbium, tantalum, and other rare elements are 

found in some wolframites, and a specimen of ferberite from the Conger mine was sent with a specimen of scheelite to Prof. G. Eberhard, 

Potsdam, Germany, who kindly made a spectroscopic analysis of them. 

In a letter dated August 20, 1912, to Adolph Knopf, of the United 

States Geological Survey, Prof. Eberhard says:

The examination of the two minerals from Mr. Hess gave the following results: 

The lines of Ba, Gl, Pb, Ga, K, Li, Na, Ni, Ag, Sn, Bi, Zn, and Zr are absent in both 

minerals. The lines of the following elements are present in ferberite:

Al, visible. Mo, weak?.

Ca, weak. Sc, weak.

Cr, weak or absent. Si, strong.

Fe, strong. . Sr, weak.

Cb, weak. Ti, weak.

Cu, weak. V, weak.

Mg, visible. W, strong.

Mn, weak. Y, absent.

I have not sought for the elements not here listed. Lines marked " weak " indicate 

that the content of the element is small or very small. Lines marked "visible " indicate that the content of the element is fairly large. Lines marked "strong" indicate 

that the content of the element is large. The element whose presence I could not 

substantiate;with absolute certainty I have marked with a question. The content 

of scandium is certainly smaller than 0.005' per cent and is therefore chemically not 

detectable.

Since this determination was made an article by H. S. Lukens 2 

has appeared, in which he describes the extraction of scandium 

from residues of Colorado tungsten ores that had been treated by the 

General Electric Co. at Schenectady, N. .Y. Lukens found 0.05 per 

cent of scandium oxide in the residues. In reply to my inquiries 

the Primes Chemical Co., which had furnished the ores, wrote, 

under date of April 18, 1914:

Regarding the scandium found in some of our ores, we have not yet located the 

point from which the ores come, but as a rule our residues contain no scandium. A 

great many tests are made right along. As we are getting ores from a great many 

points on our property, it is very difficult to tell from which particular openings they 

came. Most Boulder County ores contain no scandium. Have given samples right 

along to various universities, including the University of Pennsylvania, and though 

exhaustive "tests have been made, not one of them has found any scandium.

Another letter, dated April 27, 1914, says:

As fa'r as our records show, we shipped, with the probable exception of one small 

lot from Arizona, only Boulder County ores to the General Electric Co.

No tungstic ocher, muscovite, stibnite, bismuth minerals, fluorite, 

tourmaline, axinite, cassiterite, or topaz minerals which' in some 

places occur with wolframite deposits, particularly if closely connected 

with pegmatites are known to have been found in the Boulder field.

1 Winter Herbert, Ueber Vorkommen und Reindarstellung des Scandiums: Inaugural-Dissertation, 

Friedrich-Wilhelms-Universitat zu Berlin, pp. 22-23 et al., 1911. See also Mennicke, Hans, Die Metallurgie 

des Wolframs, pp. Ill et seq., 1911.

* Scandium to American wolframite: Am. Chem. Boc. Jour., vol. 35, pp. 1470-1472,1913.
U. S. GEOLOGICAL SURVEY BULLETIN 583 PLATE VII

A. WEDGE-SHAPED FERBERITE CRYSTALS FROM THE LONE TREE MINE, NEDERLAND,

COLO.

Fan-shaped intergrowth in right center. Coated with ammonium chloride. X 2.

]',. WEDGE-SHAPED FERBERITE CRYSTALS FROM THE HOOSIER MINE, NEDERLAND, COLO. 

Fan-shaped intergrowth and twins in lower right center. Coated with ammonium chloride. X 2.
^

U. S. GEOLOGICAL SURVEY BULLETIN 533 PLATE vm

A. CRYSTALLIZED FERBERITE FROM THE "CROW PATENT," NEDERLAND, COLO,

The crysta's are attached by the c axis and show penetration twins and reentrant angles. Coated with 

ammonium chloride. Natural size.

B. CRYSTALLIZED FERBERITE FROM THE GEORGIA A. MINE, NEDERLAND, COLO. 

Coated with ammonium chloride. X 10,
COLORADO FERBERITE AND THE WOLFRAMITE SERIES. 19

CRYSTALLIZED FERBERITE.

As has been stated, the ferberite commonly occurs in definite 

crystal forms and the beauty of the crystals is unique. However, 

although crystals are common, good specimens suitable for display 

in museums are very rare, for most of the crystals are so small that 

they appear insignificant; they are very fragile and are easily broken 

in mining; and in many places they are coated with mixtures of 

chalcedony, opal, and hydrous iron oxides in varying proportions. 

This coating may be removed from some specimens without serious 

injury by treatment with hydrofluoric and sulphuric acids, but 

crystals so treated show uneven surfaces when an attempt is made 

to measure them with a goniometer.

Probably a wedge shape is the commonest form of the crystals. 

This form occurs in many of the mines. One of the best specimens 

seen is from the Hoosier mine, between 1 and 2 miles northeast of 

Nederland (PI. VII, B). The wedge shapes are formed by the terminations at the ends of the & axis and most of the crystals are attached 

at one end of this axis. Some crystals are intergrown in such a way 

as to produce a fan shape (PL VII, A and B). In a few specimens 

crystals attached by one end of the c axis are prominent, in which 

case the termination at each end of the 6 axis is shown. Some of the 

crystals show penetration twins, extending through c{001}. Around 

the penetrating crystal in two or three occurrences there seem to be 

reentrant angles in the penetrated members (PL VIII, A). The specimen illustrated came from a tract of land known as the Crow patent, 

near Nederland.

In a specimen from the Georgia A. claim the crystals are almost 

cubic and about one one-hundredth inch (0.25 millimeter) across. 

Plate VIII, B, represents the specimen magnified 10 diameters.

Another form of crystal is found on the Nugget and the Winnebago 

claims, near Rollinsville, Gilpin County. In this form the crystal 

presents a face (&) which is a long, narrow rhomb, with a length of 

about three-eighths inch (9.4 millimeters) and a width one-tenth 

to one-fifth as much. Typical specimens are shown in Plates IX and 

X. In some specimens the rhomb has sides much more nearly 

of equal length. (See PL XI.) Plate XII shows a very fine specimen with peculiar, irregular faces. The crystal forms are described 

at length by W. T. Schaller in the latter part of this bulletin.

COMPOSITION OF FERBERITE AND OTHER MEMBERS 

OF THE WOLFRAMITE SERIES.

The original ferberite was found in the Sierra Almagrera, in southern 

Spain, and is stated by Liebe 1 to have been named by Breithaupt 

for R. Ferber, of Gera. Liebe made an analysis of the mineral. 

(See analysis No. 79, pp. 32-33.)

i Liebe, K.L.H., Ein neuer Wolframite, ein Beitrag zu Mineral Chemie: Neues Jahrb., 1863, pp. 640^563.
20 COLORADO FERBERITE AND THE WOLFRAMITE SERIES.

The next year Rammelsberg* published an article on ferberite 

with an analysis of his own material (see analysis No. 82) from the 

same locality as that described by Liebe. He quotes Liebe's analysis 

and shows that the iron oxide and tungsten trioxide are not in a 

simple ratio and that there is an excess of iron oxide. Neither 

mineral was pure, and the analyses .are not very satisfactory, so 

that calculation of iron in excess is uncertain, for it was probably 

present as an impurity and not as a part of the mineral. Liebe 

deducted 1.39 per cent limonite from his analysis.

It seems certain that the calcium present.should be calculated as 

scheelite, for scheelite almost always if not invariably accompanies 

other tungsten materials. It is not visible in all specimens to the 

unaided eye, but microscopic examination generally shows it as interstitial, inclosed in the wolframite crystals, filling vugs, or occurring 

separately in the deposit. (See PI. V, p. 14, and PI. XIII, A and B, 

p. 30.)

Some magnesium was found, but this element is not known to be a 

constituent of tungsten minerals, although A. M. Finlayson 2 gives 

an analysis of scheelite from Donaldsons, New Zealand, containing 

0.2 per cent MgO, which he considers to be combined with WO3, 

taking the place of CaO, and Damour 3 considered that both calcium 

and magnesium might take the place of iron or manganese in wolframite. That magnesium takes the place of either calcium or iron 

in tungsten minerals seems to me altogether unlikely. If it did 

so, some pure tungsten mineral that is, some mineral which could 

be shown by microscopic or other examination not to contain particles of other substances would probably be found in which the 

magnesium would form a-considerable part of the mineral, just as 

do those elements known to form natural tungstates namely, calcium, 

copper, iron, lead, and manganese. Therefore, in recalculating these 

and other analyses on pages 24-35, neither magnesium nor calcium 

has been considered as belonging to the wolframite.

To obtain a basis for differentiating ferberite Irom the remainder 

of the wolframite group all the analyses of wolframites (by which 

term is meant all members of the iron-manganese tungstate series) 

available to the author have been collected for comparison. More 

than 300 analyses were examined, but of these some represented ores 

rather than minerals; in many the W03 had been determined by 

difference, which amounts to little more than a guess; in some the 

figures gave evidence that either the analytical work was bad or that 

the material was so impure that no proper comparison of the results 

would be possible. Where several analyses of the same material were 

obtained, only one has been tabulated.

1 Rammelsberg, C. F., tiber die chemische Zusammensetsung des Ferberite: K. Akad. Wiss. Berlin 

Monatsber., Jahre 1864, pp. 175-176,1865.

2 Finlayson, A. M., The scheelite of Otago: New Zealand Inst. Trans. and Proc., vol. 40, p. 112,1908.

3 Damour, A., Sur le wolfram tantalifere du dSpartement de la Haute-Vienne: Soc. ge"ol. France Bull., 

2d ser., vol. 5, p. 108,1848.
U. S. GEOLOGICAL SURVEY BULLETIN 583 PLATE IX

CRYSTALLIZED FERBERITE WITH ELONGATED RHOMBIC CRYSTAL FACES. 

From the Nugget mine, Gilpin County, Colo. Coated with ammonium chloride. Natural size.
U. S. GEOLOGICAL SURVEY BULLETIN 583 PLATE X

CRYSTALLIZED FERBERITE WITH ELONGATED RHOMBIC CRYSTAL FACES.

From the Nugget mine, Gilpin County, Colo. Coated with ammonium chloride. Natural size. 

-4. Edge view. J{, Side view.
COMPOSITION OF FERBERITE AND OTHER MEMBERS OF SERIES. 21

The analyses have all been recalculated in order to bring them to 

a common basis on which they can properly be compared.

To do this it has been assumed that the theoretically pure members 

of the wolframite series contain only the hubnerite molecule, MnW04 ; 

the ferberite molecule, FeW04 ; or a combination of the two molecules. All analyses have been reduced to these simple forms.

As scheelite, the calcium tungstate, CaWO4 , almost universally 

accompanies the wolframites, the lime indicated in the analyses has 

been considered to be a component of scheelite unless data given 

with the analysis showed it to belong to some other mineral, such as 

fluorite. As the CaO is an impurity, it has therefore ordinarily been 

satisfied with W03 and then discarded with all items other than FeO, 

MnO, and W03 . Of course, this scheme probably leads to error in 

certain of the analyses, as the lime in some may be derived from 

other sources than scheelite, but these sources can not all be known,

and as a general rule the process just described seems warranted. 

As applied to the Boulder field in particular there can be little objection, as lime-bearing minerals other than scheelite are uncommon. 

Calciferous feldspars seem to occur in very few places, calcite is rare, 

and no other lime minerals have been noted in the veins.

The analyses have been arranged in a series of decreasing MnW04 

and increasing FeW04 content, so that the series begins with the 

hubnerites and ends with the ferberites. This has determined the 

order of calculation, for the natural procedure has been to satisfy first 

the MnO with W03 and then to combine the remaining W08 with 

so much of the FeO as it would take up. Arbitrary or casual reasons 

are not the only bases for this mode of calculation, however, for manganese is much less common as an impurity in wolframites than is iron.

The quantity of MnW04 and FeW04 obtained as a result of the 

operations has then been treated as the theoretically pure wolframite 

present in the substance analyzed, all other substances present being 

considered as impurities. From the theoretical wolframite as a basis 

have been computed the percentages of W03, FeO, MnO, FeW04 , and 

MnW04 of which it is composed.

In making the calculations the following atomic values and molecular ratios have been used:

Atomic weight.

Calcium .......................... 40

Iron............................... 56

Manganese........................ 55

Oxygen ........................... 16

Tungsten......................... 184

The values of the atomic weights are used only to the nearest 

integer and the ratios to the second decimal. These values are as

Molecular ratio. 

8 -~---------------------- 4-14

W0a_232

FeO ~~ ~72 --.- - 3. 22

W08 232

-.. .................... 3.27
22 COLORADO FERBERITE AND THE WOLFRAMITE SERIES.

exact as are warranted by the errors due to the uncertainty of the 

constituent minerals of the analyzed material and to the faults of 

analysis.

As an example of the process of calculation, analysis 37 maybe 

taken:

Analysis of wolframite from Hill City, S. Dak. 

Tungsten trioxide (W03)...................................... 71. 0

Ferrous oxide (FeO).......................................... 14. 3

Manganous oxide (MnO)...................................... 10. 2

Lime (CaO)................................................... 0.7

Silica (Si02).......................:.......................... 2.9

Magnesia (MgO)............................................... None.

Water (H20)................................................. 0. 3

99.4

W03 

CaO CaO W03

0.7 X 4.14 = 2.9

CaO W03 CaW04

0.7 + 2.9 =3.6

WOj 

MnO MnO . WO8

10.2 X 3.27 = 33.4

MnO W03 MnWO4

10.2 + 33.4 = 43.6 

W03 required to satisfy the CaO and MnO........................ 36.3

W03 in analysis................................................. 71. 0

Less quantity for CaO and MnO................................ 36. 3

WOS to be satisfied by FeO............................... 34.7

FeO required to 

satisfy reWUa mainder of 

WO3 FeO WO3 .

34.-7 H- 3.22 = 10.8

WO3 FeO FeW04

34.7 + 10.8 = 45.5

FeO in analysis.................................................. 14. 3

FeO required................................................... 10.8

Excess of FeO............................................ 3. 5

Adding the MnW04 and FeW04,

Hubnerite (MnWO4)............................................ 43. 6

Ferberite (FeW04) ............................................ 45. 5

Theoretical wolframite in the material analyzed............ 89.1
U. S. GEOLOGICAL SURVEY BULLETIN 583 PLATE XI

FERBERITE WITH RHOMBIC CRYSTAL FACES. 

From the Nugget mine, Gilpin County, Colo. Coated with ammonium chloride. Natural size.
U. S. GEOLOGICAL SURVEY 

VERY FINE SPECIMEN OF FERBERITE WITH RHOMBIC 

From the Nugget mine, Gilpin County, C^;0. Coated ,/ith ammonium 
COMPOSITION OF FERBEKITE AND OTHEE MEMBEKS OF SERIES. 23

Recalculating to percentages of the theoretical wolframite and then 

breaking up into oxides,

Hubnerite (MnW04).... ....... ............ 48..9=Ul..5 MnO+37. 4 W03

Ferberite (FeW04). ....................... 51. 1=12. 1 FeO +39. 0 W03

Total W03 in theoretical wolframite. .................. 76. 4

The presence of water (0.3) in the analysis probably indicates that 

a part of the apparent excess of FeO (3.5) is limonite. The 0.3 per 

cent of water will combine with 1.6 per cent of FeO to form 2.1 per 

cent of limonite, considered as 2Fe2O3 .3H2O. This still leaves an 

excess of 1.9 per cent FeO.

Summarizing, the calculation shows the wolframite to have a composition of 

WO...................... 76.4

With which is associated in the mass scheelite, CaW04, 3.6; excess 

FeO, 1.9; limonite, 2,1.
24 COLORADO FERBERITE AND THE WOLFRAMITE SERIES.

Analyses of minerals of

No.

1 

2 

3

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16

17 

18

Locality.

HOBNEEITE.

Philipsburg, Mont. .......... 

Ouray County, Colo.. . .......

White Oaks, N. Hex. ........

"M"VA f niirifv "WAV

Schlaggenwalde, Bohemia. . . . 

Bayevka, Russia. ............ 

North Star mine, Colo. . ...... 

Lawrence County, S. Dak. . . .

Patterson Creek, Idaho. ...... 

Sunday Gulch, S. Dak. . ..... 

Dragoon Mountains, Ariz .... 

Bonito Mountain," N. Mex. . . .

Bayevka, Russia. ............

Original analysis.

W03 .

74.82 

75.58 

74.28 

75.45 

74.88

74.12

70.21 

71.50 

74.32 

74.75 

75.12 

76.63 

75.94 

74.46 

75.36 

76.33

76. 50

76.61

FeO.

0.06 

.24

.47 

.55 

.56

1.42

2.03 

5.40 

2.11 

2.91 

3.01 

1.61 

2,38 

3.29 

2.66 

3.82

4.40

4.64

MnO.

25.00 

23.40 

22.73 

23.31 

23.87

23.21

21.72 

23.10 

20.90 

21.93 

20.54 

21.78 

21.57 

19.90 

19.50 

19.72

18.50

18. 59

CaO.

"o.'is"

.02 

.32 

.14

.37 "i.'so"

.11 

1.04 

.09

"i'05"

.13 

.20

.17

SiOz.

"6" 62" 

1.33

.48

4.91 

""."28"

""."42" 

1.70

.70.

MgO.

"o.'se"

None. 

.08

Trace. 

Trace."

Trace. 

None.

.20

Other substances. 

"c"bV66?,6!65.'!! MoOs, trace... 

(Cb.Ta) 206 ?... 

CuO,0.08.....

A12O3,0.56....

S, 0.01. ........ 

Ignition, 0.75.. 

Undet., 0.78. . .

Total

99.88 

100.02 

99.69 

100. 51 

99.61

99.80 

100.00 

98.91 

99.70 

99.71 

100.11 

99.90 

99.87

100.00

100.30 

100.21

. 1. Hiibnerite from Philipsburg, Mont. Analysis by A. H. Low .quoted from Richard 

Pearce by Hillebrand, W. F., Miscellaneous mineral notes; Contributions to the mineralogy of the Rocky Mountains: U. S. Geol. Survey Bull. 20, p. 96, 1885.

2. Hiibnerite from the Royal Albert vein, Uncompahgre district, Ouray County, 

Colo. Hillebrand, W. F., Miscellaneous mineral no'tes; Contributions to the mineralogy of the Rocky Mountains: U. S. Geol. Survey Bull. 20, p. 96, 1885.

3. Hiibnerite from Emerald, Nova Scotia. Johnston, R. A. A., Hiibnerite: Canada Geol. Survey Ann. Rept., new ser., vol. 11, p. 10R, 1898.

4. Hiibnerite from the South Homestake mine, White Oaks, N. Mex. Analysis 

by J. G. Dinwiddie. Besides the items given the analysis showed H2O at 110° C., 

none; H20 above 110° C., 0.40. This hiibnerite is to the unaided eye as black as 

the ferberite of the Boulder field, but in thin section it is translucent brown and .olivegreen. The streak is olive-green. Microscopic examination showed no scheelite 

but much fluorite, so that the calcium has been considered as derived from that 

mineral. See also analysis 16.

5. Hiibnerite from Riotte's original locality, Ellsworth, Mammoth district, Nye 

County, Nev. Genth, F. A., Contributions to mineralogy, No. 52; with crystallographic notes by S. L. Penfield: Am. Jour. Sci., 3d ser., vol. 43, p. 187, 1892.

6. Hiibnerite from Morococha, Peru. Analysis by Pfliicker quoted by Domeyko, 

Ignacio, Mineralojia, vol. 2, p. 92, 1897.

7. Hiibnerite from the Natalie mine, Silverton, Colo. Ekeley, J. B., Some Colorado 

tungsten ores: Min. World, vol. 30, p. 280, 1909.

8. Hiibnerite from Schlaggenwalde, Bohemia. Rammelsberg, C. F., Handbuch 

der Mineralchemie, p. 309,1860. Fine red brown needles, with fluorspar and apatite.

9. Average of two analyses of hiibnerite from Bayevka, Ural Mountains, Russia. 

Koulibin, Von N. v., Manganhaltiger Wolfram aus der Grube Bajewsk am Ural: 

Russ.-k. mineral. Gesell. St. Petersburg Verb.., vol. 3, 2d ser., p. 3, 1868.

10. Hubnerite from the North Star mine, Silverton, Colo. Genth, F. A., Contributions to mineralogy, No. 52; with crystallographic notes by S. L. Penfield: Am. Jour. 

Sci., 3d ser., vol. 43, p. 186, 1892.
COMPOSITION OF FERBERITE AND OTHER MEMBERS OF SERIES. 25 

the wolframite series.

No.

1

2 

3 

4 

5 

6 

7 

8 

9, 

10 

11 

12 

13 

14 

15 

16

17 

18

^Recalculated analysis.

W03.

76.6 

76.6 

76.6 

76.6 

76.6 

76.6 

76.6 

76.6 

76.6 

' 76.6 

76.6 

76.6 

76.6 

76.6 

76.5 

76.6

76.6 

76.5

FeO.

0.2 

.8 

1.4 

1.6 

1.6 

1.7 

2.8 

3.5

4.5

4.7

MnO. .

23.4

23.4

23.4

23.4

23.4

23.4

23.4

23.4

23.2 

22.6 

22.0 

21.8 

21.8 

21.7 

20.7 

19.9

18.9 

18.8

FeW04.

0.8 

3.2 

6.0 

6.7 

6.9 

7.2 

11.6 

14.9

19.1 

19.8

MnW04 .

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

99.2 

96.8 

94.0 

93.3 

93.1 

92.8 

88.4 

85.1

80.9 

80.2

Excess 

FeO.

0.1 

.2 

.5 

.6 

.6 

1.4 

2.0 

5.4 

1.9 

2.3 

1.2 

.1 

.8 

1.7 

.1 

.3

Excess 

MnO.

2.1 

.5

.2 

1.2

.5

.7 r.2

Excess 

WO8 .

1.7

.1

CaW04 .

0.7 

.1

.7

1.9

6.7 

.6 

v 5.4

.5

4.4 

4.1 

.7

1.0 

1.0

Specific 

gravity.

7.177

6.45 

7.357 

6.713

6.891

7.163

7.20 

7.267

11. Hiibnerite from the Comstock mine, Lawrence County, S. Dak. Headden, 

W. P., Mineralogical notes: Colorado Sci. Soc. Proc., vol. 8, p. 175, 1906. "A black 

mineral fairly well crystallized."

12. Hiibnerite from Cement Creek, Silverton, Colo. Genth, F. A., Contributions 

to mineralogy, No. 52; with crystallographic notes by S. L. Penfield: Am. Jour. Sci., 

3d ser., vol. 43, p. 186, 1892.

13. Hiibnerite from the Idaho Tungsten Co.'s property in the Blue Wing district, 

on Patterson Creek, Lemhi County, Idaho.' An unpublished analysis by J. E. 

Talmadge, communicated by J. G. Lind. It seems improbable that from these 

deposits a specimen could be selected, the analysis of which would show neither Si02 

nor CaO, but this is of course surmise. In the analysis given, were the ordinary error 

of high MnO made, it might account for the good summation, were other elements 

undetermined. On the other hand, manganese oxides occur in the vein in some 

quantity (see Umpleby, J. B., Geology and ore deposits of Lemhi County, Idaho: 

U. S. Geol. Survey Bull. 528, pp. 3, etc., 1913), and it may well be that they are present 

in interstices of the hiibnerite, part of which is so dark as to suggest the inclusion of 

either manganese or iron oxides.

14. Hiibnerite from Sunday Gulch, near Hill City, S. Dak. Headden, W. P., 

Mineralogical notes: Colorado Sci. Soc. Proc., vol. 8, p. 176,1906. "Granular, almost 

entirely free from admixed gangue" (p. 175).

15. Hiibnerite from Dragoon Mountains, Ariz. Guild, F. N., The mineralogy of 

Arizona, p. 92, 1910.

16. Hiibnerite from Bonito Mountain, near White Oaks, N. Mex. Genth, F. A., 

Contributions to mineralogy, No. 52; with crystallographic notes by S. L; Penfield: 

Am. Jour. Sci., 3d set., vol. 43, p. 187, 1892.

17. Hiibnerite from Oroville, Wash. B. C. Wells, of the U. S. Geol. Survey, 

analyst. Si02 includes any other insolubles. Ta, Cb, Sn, Mo, and rare earths are not 

present in appreciable quantities.

18. Average of two analyses of hiibnerite from Bayevka, Ural Mountains. Beck, 

W., and Teich, N., Ueber Wolfram und Scheelit aus Fundorten Busslands: Buss.-k. 

mineral. Gesell. St. Petersburg Verh., 2d ser., vol. 4, pp. 315-316, 1869.
26 COLORADO FEEBERITE AND THE WOLFRAMITE SERIES.

Analyses of minerals of

No.

19 

20 

21 

22 

23 

24 

25 

26 

27 

28 

29 

30

31

32 

33 

34 

35 

36 

37 

38

Locality.

WOUEAMITE.

Whetstone Mountains, Ariz. . 

Zinnwald, Germany ......... 

Zinnwald, Bohemia. ......... 

Zinnwald (Germany ?)....... 

Lake Couchiching, Ontario... 

Zinnwald, Germany ......... 

Altenberg, Germany. ........

Zinnwald, Germany ......... 

 Freiberg, Germany. ......... 

Schlaggenwalde, Bohemia. . . . 

Zinnwald (Germany?) .......

.....do.......................

Cornwall, England ...........

Vilate, France.. ............. 

Sudzukoya, Japan. ........... 

Hill City, S. Dak. . ..........

Sierra Cordoba, Argentina. . . .

Original analysis.

WO3 .

74.20 

76.20 

76.50 

73.60 

73.45 

75.62 

75.44

76.01 

75.84 

75.68 

75.99 

76.34

75-62

72.80 

74.84 

74.90 

73.93 

71.90 

71.00 

74.86

FeO.

5.15 

5.60 

10.30 

11.20. 

9.05 

9.55 

9.64

9.81 

9.20 

9.56 

9.62 

9.61

8.73

11.44 

10.81 

10.60 

12.97 

15.29 

14.30 

13.45

MnO.

18.09 

17.94 

12.20 

15.75 

15.35 

14.85 

14.90

13.90 

14.56 

14.30 

13.96 

14.21

12.17

12.08 

12.55 

12.80 

11.60 

10.64 

10.20 

11.02

CaO.

"i.'io"

1.19

""."48"

2.27

1.18 

.80 

.30

""."76"

SiOj.

1.95

""."26"

.......

2.36 

.30 

.90

"i."62" 

2.90

MgO.

Trace!

.12

Trace?

None.

Other substances.

SnOj, trace. . . 

'CbV65?,"i."95.'"

fTi"6si.89......

rljU, U.ol. .... 

Loss. 0.14.....

(Ta,Cb) 2O6,0.26 

PbO, trace?... 

Ta206 , 1.03.... 

Undet., 1.15.-

H2 0,0.30....,

Cb2 03) 1.22....

Total.

99.39 

99.74 

100.10 

100.55 

100.00 

100.02 

99.98 

100.91 

99.60 

99.54 

100.05 

100.16

|lOO. 99

100.00 

100. 38 

100.10 

99.53

99.40 

100.55

19. Wolframite from the Whetstone Mountains, 12 miles south of Benson, Ariz. 

Analysis by J. M. Ruthrauff quoted by Guild, F. N., The mineralogy of Arizona, 

p. 94, 1910.

20. Wolframite from Zinnwald, Germany. Bernoulli, F. A., Ueber Wolfram und 

einige seiner Verbindungen: Poggendorf's Annalen, 4th ser., vol. 21, p. 604, 1860.

21. Wolframite from Zinnwald, Bohemia. Helmhacker, R., Wolfram ore: Eng. 

and Mn. Jour., vol. 62, p. 154, 1896.

22. Wolframite from Zinnwald (Germany?). Richardson, T., Analysis of wolfram: 

Thomson's Records of general science, vol. 1, p. 451, 1835.

23. Wolframite from Lake Couchiching, Ontario. Hunt, T. S., Analysis of Canadian 

wolfram: Canadian Jour., new ser., vol. 5, p. 303, 1860.

24. Wolframite from Zinnwald, Germany. Kerndt, T., Ueber die Krystallform und 

chemische Zusammensetzung der natiirlichen und kiinstlichen Verbindungen dea 

Wolframmetalles: Jour, prakt. Chemie, vol. 42, p. 97, 1847.

25. Wolframite from Altenberg, Germany. Kerndt, T., Ueber die Krystallform 

und chemische Zusammensetzung der naturlichen und kiinstlichen Verbindungen 

des Wolframmetalles: Jour, prakt. Chemie, vol. 42, p. 110,1847.

26. Wolframite from Zinnwald, Germany. Schneider, R., Ueber die chemische 

Constitution des Wolframminerals: Jour, prakt. Chemie, vol. 49, p. 332,1850.

27. Wolframite from Neubeschert-Gliick, Freiberg, Germany. Kerndt, T., Ueber 

die Krystallform und chemische Zusammensetzung der naturlichen und kiinstlichen 

Verbindungen des Wolframmetalles: Jour, prakt. Chemie, vol. 42, p. 102, 1847.

28. Wolframite from Schlaggenwalde, Bohemia. Kerndt, T., Ueber die Krystallform und chemische Zusammensetzung der naturlichen und kunstlichen Verbindungen des Wolframmetalles: Jour, prakt. Chemie, vol. 42, p. 109, 1847.,

29. Wolframite from Zinnwald, Germany (?). Ebelmen, J. J., Note sur la composition du wolfram: Annales des mines, 4th ser., vol. 4, p. 407,1843.

30. Wolframite from Zinnwald, Germany. Kerndt, T., Ueber die Krystallform 

und chemische Zusammensetzung der naturlichen und kunstlichen Verbindungen 

des Wolframmetalles: Jour, prakt. Chemie, vol. 42, p. 96, 1847.
COMPOSITION OF FERBERITE AND OTHER MEMBERS OF SERIES. 27 

the wolframite series Continued.

No.

19 

20 

21 

22 

23 

24 

25 

26 

27 

28 

29 

30

31 

32 

33 

34 

35 

36 

37 

38

Recalculated analysis.

WO*.

76.5 

76.6 

76.5 

76.5 

76.5 

76.5 

76.5 

76.5 

76.5 

76.5 

76.5 

76.5

76.5 

76.5 

76.5 

76.4 

76.4 

76.4 

76.4 

76.4

FeO.

4.8 

5.4 

6.4 

7.1 

7.5 

8.5 

8.6 

8.7 

8.7 

9.1 

9.1 

9,3

9.4 

9.9 

10.1 

10.3 

11.6 

12.1 

12.1 

12.3

MnO.

18.7 

18.0 

17.1 

16.4 

16.0 

15.0 

14.9 

14.8 

14.8 

14.4 

14.4 

14.2

14.1

13.6 

13.4 

13.3 

12.0 

11.5 

11.5 

11.3

FeWCM.

20.3 

23.0 

. 27. 1 

30.1 

31.5 

35.8 

36.3 

36.6 

37.3 

38.3 

38.4 

 39.2

39.8 

41.9 

42.7 

43.3 

48.8 

50.9 

51.1 

51.9

MnWCK

79.7 

77.0 

72.9 

69.9 

68.5 

64.2 

63.7 

63.4 

62.7 

61.7 

61.6 

60.8

60.2 

58.1 

57.3 

56.7 

51. 2 

49.1 

48.9 

48.1

Excess 

FeO.

0.5

.2 

4.6 

4.3 

1.9 

1.2 

1.2 

1.7 

.4 

.6 

. .8 

.3

.5 

2.6 

1.9 

.7 

1.8 

4.0 

1.9 

1.4

Excess 

W03 .

(a)

CaWCK

5.7

6.1

2.5

11.7

6.1 

4.1 

1.5

3.6

Specific 

gravity.

7.017

7.230 

7.198

7.229 

7.535

7.272 

7.000

o Limonite 2.1 per cent.

Si. Wolframite from Zinnwald, Germany. Weidinger, G., Analyse eines Wolframkrystalls aus den Gruben bei saAhsisch .Zinnwald an der bohmiech-sachsiechen 

Grenze: Zeitschr. Pharm., vol. 7, p. 73,1855.

32. Wolframite presumably from the property of the Mount Pima Mining Co. (Ltd.), 

Tenasserim, Lower Burma. A published analysis by 0. Burger furnished through 

the courtesy of Radcliff & Co., Rangoon, Burma.

33. Wolframite from Cornwall, England. The exact locality of origin is unknown. 

Analysis by Edgar T. Wherry on specimen No. 80179 in the United States National 

Museum. The analysis, which will appear in the Proceedings of the Museum, showed, 

besides the items given: Fe203 , 0.70, which was calculated to its equivalent of FeO 

and added to that item. The wolframite is black and opaque and occurs in large 

crystals with pyrite and chalcopyrite. A section showed a later deposition of very 

thin bands of scheelite and wolframite in cracks of the crystals, so that the CaO evidently should be calculated into scheelite.

34. Wolframite from Lost River, Alaska. R. C. Wells, of the U. S. Geol. Survey, 

analyst. No Ta, Cb, Mo, or rare earths present.

35. Wolframite from between Vilate and Chanteloube, France. Damour, A., Sur 

le wolfram tantalifere du de"partement de la Haute-Vienne: Soc. ge'ol. France Bull., 

2d ser., vol. 5, p. 108, 1848.

36. Wolframite from Takatori mine, Takatori Mountain, near Sudzukoya, HigashiIbaraki County, State of Hitachi, Japan. The mine is 12 miles northwest of Mito and 

14 miles northeast of Kasama. Analysis by S. Katsuno, personal communication, 

Nov. 30,1912.

37. Wolframite from Black Metal claims, Hill City, S. Dak. R. C. Wells, of the 

U. S. Geol. Survey, analyst. Any A1203 present is included with the FeO.

38. Wolframite from the southern end of the Sierra Cordoba, Argentina. Bodenbender, G., Die Wolfram-Minen der Sierra von Cdrdoba in der Argentinischen Republik: Zeitschr. prakt. Geologie, Nov., 1894, p. 409.
28 COLORADO FERBERITE AND THE WOLFRAMITE SERIES.

Analyses of minerals of

No.

39 

40 

41 

42 

43 

44 

45 

46

47

48 

49 

50 

51 

52

Locality.

WOLFRAMITE continued . 

Lead, S. Dak................

Montebelleux, France. ....... 

Sadisdorf, Germany. ......... 

.....do.......:............... 

Tavoy, Burma. ..............

Wheal Gorland, Cornwall.... 

Northwest Spain.............

Quebrada de la Viuda, 

Argentina. 

Miramichi River, New 

Brunswick. 

Altai, Siberia................ 

Ward, Colo............ ...... 

Felso banya, Hungary . _ ....

Wheal Gorland, Cornwall. . . .

Original analysis.

W03 .

61.70 

76.21 

70.38 

73.47 

74.78 

51.00 

64.13 

75.07

74.43

75.56 

71.27 

76.14 

73.46

57.18

FeO.

9.18 

12.87 

13.88 

15.13 

13.80 

20.20 

10.88 

15.61

16.90

16.22 

20.01 

15.67 

16.90

15.87

MnO.

8.21 

10.52 

9.52 

9.81 

9.36 

6.07 

6.42 

8.24

8.37

8.42 

7.15 

8.34 

6.97

5.30

CaO.

0.93

"2." 16* 

.54 

Trace.

!52

"i."58"

.......

Si02.

12.87 

.15

""."36" 

1.83 

7.71

"2."69"

6.83

MgO.

Trace. 

Trace. "s.'ie"

.31

.......

Other substances.

Cb'sOs, 6.20 . . 

As, -3.82....... 

Sn02 , 0.68..... 

Cb2O3 , 1.12....

As, 2.39.......

Total.

99.64 

99.75 

100. 70 

100.05 

100. 12

"99.' 89" 

100. 87

99.70

100.20 

100.01 

100.15 

100.02

39. Wolframite from Two Strike mine, Yellow Creek, Lead, S. Dak. W. F. Hillebrand, analyst. Irving, J. D., Economic resources of the northern Black Hills: U. S. 

Geol. Survey Prof. Paper 26, p. 167, 1904. Besides the items noted, the analysis 

showed: Fe203 , 3.85; A1203> 0.52; SrO, 0.02; BaO, 0.04; K20+Na20+Li20, 0.08; 

H20, below 105° C., 0.20; H20 above 105° C., 0.87; As20s, 1.25; P206, 0.12; traces of 

V2Os and S or S03 . Extremely minute traces of Zn, Cu, Sb, and Sn were also found. 

Assays gave: Gold 0.05 ounce and silver 0.25 ounce to the ton of 2,000 pounds. The 

P205 was probably combined with CaO as apatite, and 0.18 has therefore been deducted 

from the CaO before combining it with W03 for scheelite. The FeO is not sufficient, 

as indicated by the analysis, to combine with the W03 , and 0.6 must be taken from the 

Fe203 to supply the deficiency.- A partial analysis of a specimen from the Harrison 

mine, near Lead, is given, as follows: Si02 , 9.60; W03 , 61.70; Fe203 and FeO, 12.67, 

MnO, 7.21; CaO, 5.39. Recalculated: W03, 76.5; FeO, 9.5; MnO, 14.0; FeW04 ; 

40.2; MnW04 , 59.8; CaW04 ,39.4. In this analysis the CaO (5.39) is high, and no determination of P20S is indicated. There is no corresponding increase in the W03 and 

the relation of the FeO: MnO is so much different as to indicate that part of the lime 

probably belongs in apatite. Specimens of ore collected by the present writer from

this general locality and examined microscopically show apatite in small quantity. 

As given, the analysis falls between Nos. 31 and 32.

40. Wolframite from Montebelleux, Brittany, France. Bourion, F., Sur un mode 

ge"ne"ral de preparation des chlorures anhydres et ses applications a 1'analyse chimique: 

Annales chim. phys., 8th ser., vol. 21, p. 103,1910.

41. Wolframite from the Kupfergrube, Sadisdorf, Germany. Winter, H., Ueber 

Vorkommen und Reindarstellung des Scandiums: Inaugural-Dissertation, FriedrichWilhelms-Universitat zu Berlin, p. 23,1911. Besides the items mentioned, the analysis shows P04 , 2.23; Mo03 , trace; earth acids (Ta02 , Ti02), 2.07; PbO, 0.46; Sc, 0.2. 

It is stated that calcium phosphate was present in the gangue, and the CaO has therefore been combined with the P04 , which it is hardly sufficient to satisfy.

42. Wolframite from the Kupfergrube, Sadisdorf, Germany. Winter, H., Ueber 

Vorkommen und Reindarstellung des Scandiums: Inaugural-Dissertation, FriedrichWilhelms-Universitat zu Berlin, p. 22, 1911. The analysis also showed: Ti02 and 

Ta02 , 0.63; PbO and Sn02 , 0.47; Sc, 0.2.

43. Wolframite from the Tavoy district, Lower Burma. Analysis by C. S. Fawcitt. 

Bleeck, A. W. G., On some occurrences of wolframite lodes and deposits in the Tavoy 

District of Lower Burma. India Geol. Survey Records, vol. 43, pt. 1, pp. 67-68,1913.
COMPOSITION OF FEBBEBITE AND OTHER MEMBERS OF SERIES. 29

the wolframite series Continued.

No.

39 

40 

41 

42 

43 

44 

45 

46

47

48 

49 

50 

51

to.

Recalculated analysis.

W08 .

76.4 

76.4 

76.4 

76.4 

76.4 

76.4 

76.4 

76.4

76.4

76.4 

76.4 

76.4 

76.4 

7fi.l

FeO.

12.8 

13.0 

13.2 

13.4 

14.0 

14.5 

14.9 

15.0

15.0

15.1 

15.1 

15.2 

16.3 

1fi.fi

MnO.

10.8 

10.6 

10.4 

10.2 

9.6 

9.1 

8.7 

8.6

8.6

8.5 

8.5 

8.4 

7.3 

7.0

FeWO<.

54.1 

54.8 

55.8 

56.4 

59.2 

61.0 

62.8 

63.2

63.3

63.6 

63.8 

64.3 

69.0 

70.0

MnWO<.

45.9 

45.2 

44.2 

43.6 

40.8 

39.0 

37.2 

36.8

36.7

36.4 

36.2 

35.7 

31.0 

30.0

Excess 

FeO.

1.7 

3.0 

.1 

. (?)

1.3 

2.3

1.3 

7.2 

.5 

1.2 

.2

Excess 

WO3 .

0.2

3.1

CaWO4 .

4.0

2.8

6.2 

' 2.7

8.1

Specific 

gravity.

6.968

7.458

Besides the items noted in the table, the analysis shows A1203 , 0.81; Bi203 , 0.14; 

Sn02 , trace; Mo03 , 0.51; H20, 0.22.

44. Ore from Wheal Gorland, Cornwall. Analysis by B. Kitto, communicated by 

Mr. R. Woodward, managing director of Edgar Alien & Co. (Ltd.), Sheffield, England. 

The analysis also shows: Pb, 0.10; Mg, trace; Bi, 0.15; P, trace; CaF2 , 4.06; Cu, 0.88; 

8,2.02; A1203 ,1.77; Sn02 , 8.64; 0, by difference, 3.96. Cu, Fe, S, and As were combined as nearly as possible to form chalcopyrite and arsenopyrite. Although not made 

on as pure material as might be wished for the purposes of this paper, the analysis shows 

approximately the composition of the wolframite.

45. Wolframite from northwest Spain (ore). Steinhart, 0. J., Classification, occurrence, identification, and properties of tungsten ores: Mineral Industry, vol. 17, p. 830, 

1909. The analysis also shows: A1203 , 5.32; and CrO, 0.38.

46. Wolframite from Qiiebrada de la Viuda, Department of San Xavier, Argentina. 

Bodenbender, G., Die Wolfram-Minen der Sierra von C6rdoba in der Argentinischen 

Republik: Zeitschr. prakt. Geologic, Nov., 1894, p. 409. A trace of CaO is present but no MgO.

47. Wolframite from the confluence of the southwest Miramichi and Burnt Hill 

Brook, New Brunswick. Walker, T. L., Recently discovered wolframite deposits in 

New Brunswick: Econ. Geology, vol. 6, p. 397, 1911.

48. Wolframite from Kolywanowschen mine, Altai, Siberia. Beck, W., and Teich, 

N., Ueber Wolfram und Scheelit aus Fundorten Russlands: Russ.-k. mineral. Gesell. 

St. Petersburg Verh., 2d ser., vol. 4, p. 317, 1869.

49. Wolframite from Ward, Colo. Analysis by J. B. Ekeley. George, R. D., The 

main tungsten area of Boulder County, Colo.: Colorado Geol. Survey First Rept., 

p. 43, 1909.

50. Wolframite from Felsobanya, Hungary. Sipocz, L., Ueber die chemische 

Zusammensetzung einiger seltener Minerale aus Ungarn: Min. pet. Mitt., new ser., 

vol. 7, p. 270, 1886.

51. Wolframite from Perilhao, Portugal. Bourion, F., Sur un mode ge"ne"ral de 

preparation des chlorures anhydres et ses applications a 1'analyse chimique: Annales 

chim. et phys., 8th ser., vol. 21, p. 104, 1910.

52. Ore from Wheal Gorland, Cornwall. Analysis by B. Kitto, communicated by 

Mr. R. Woodward, managing director of Edgar Alien & Co. (Ltd.), Sheffield, England. 

Fe (12.34) has been calculated as FeO (15.87). The analysis also shows: Sn02 , 2.75; 

traces of Pb and MgO; CaF2 , 4.37; Cu, 0.45; S, 1.31; A1203 , 4.13; and 0, by difference, 2.95.
30 COLORADO FERBERITE AND THE WOLFRAMITE SERIES.

Analyses of minerals of

No.

53 

54

55 

56

57

58

59 

60 

61 

62

63 

64 

65 

66 

67

Locality.

WOLFRAMITE continued.

.....do. ......................

Orevflle, S. Dak....... .......

Mount Carbine, Queensland. .

Gordon Gulch, Colo. .........

Cabarrus County, N. C. ...... 

Neudorf, Germany. .......... 

Pioche, Nev.................

Irish Creek, Va. .....:........

Stassberg, Germany .......... 

Cedar Canyon, Wash. . ....... 

Chanteloube, France .........

Montevideo.. ...............

. " ' Original analysis.

WO3 .

.74.75 

74.25

76.00 

76.24

71.2

60.84

75.79 

76.21 

70.73 

74.56

76.57 

75.73 

75.82 

75.90

76.02

FeO.

. 16. 17 

 15.85

17.00 

16.39

 18.0

18.36

19.80 

18.54 

16.42 

15.19

18.98 

18.68 

19.33 

 19.25

19.21

MnO.

6.40 

6.51

6.60 

6.05

6.0

4.73

5.35 

5.23 

4.71 

3.84

4.90 

4.93 

4.84 

4.80

4.75

.CaO.,

0.40 

.80

.20 

1.05

.32 

.40 

.50 4; 10

. .70

Si02 .

1.12

.90

4.0 

16.28

""."26" 

""."36"

MgO.

0.17 

.04

None. 

.11

""."36" 

.14 

.41

Trace.

Other substances.

Ta205 , 0.95.... 

/H20.0.70..... 

\Ta206, 1.10....

/Bi, 0.1. .......

\Cu.0.2........

|P 0 05

SnOj, trace....

"(Ta",Cb)Vd6Vo".82 

(Ta,Cb)206,etc., 

0.96.

"Und"et".,"o".22!."

Total.

99.96 

} 99.25

100. 70 

99.84

101.26 

100. 74 

97.08 

100.20

101. 15 

99.92 

99.99 

99.95 

99.98

53. Wolframite from Meymac, Correze, France. Carnot, A., Sur quelques mine1 - 

raux de tungstene de Meymac (Correze): Compt. Rend., vol. 79, p. 638, 1874. Any 

alumina present is included with the silica;

54. Wolframite'from Meymac, Correze, France. Carnot, A., Sur quelques mine'- 

raux de tungstene de Meymac (Correze): Compt. Rend., vol. 79, p. 638, 1874.

55. Wolframite from "Wolfram" claim, 3 miles east of Oreville, S. Dak. R. C. 

Wells, of the U. S. Geol. Survey, analyst. Si02 includes any other insolubles. Ta, 

Cb, Sn, Mo, and rare earths are not present in appreciable quantities.

56. Wolframite from Carrock Fell, England. Finlayson, A. M., The ore-bearing 

pegmatites of Carrock Fell and the genetic significance of tungsten ores: Geol. Mag., 

vol. 7, p. 21, 1910.

57. Wolframite. Analysis of "typical Mount Carbine [Queensland] wolfram concentrate" by Alex. Gumming. The Si02 (4.0) includes "insol., etc." Besides the 

items in the table there is also "undetermined, 0.5." Quoted by Ball, L. C., Wolfram mines of Mount Carbine. No. 1: Queensland Govt. Min. Jour., vol. 14, p. 70, 

1913. .

58. Ore from Gordon Gulch, Boulder County, Colo. Greenawalt, W. E., The 

tungsten deposits of Boulder County, Colo.: Eng. and Min. Jour., vol. 83, p. 951,1907. 

The analysis also, includes: Gold, trace; silver, 3.1 ounces to the ton. The item 

.given under Si02 is given by Greenawalt as "Si."

59. Wolframite -from the Flowe mine, Cabarrus County, N. C. Genth, F. A., The 

minerals of North Carolina: U. S. Geol. Survey Bull. 74, p. 80, 1891.

60. Wolframite from Grube Pfaffenberg, Neudorf, Harz Mountains, Germany. 

Schneider, R., Ueber die chemische Constitution des Wolfram-Minerals: Jour, prakt. 

Chemie, vol. 49, p. 334, 1850.

61. Black wolframite from Silver Comet mine, 11 miles west of Pioche, Nev. J. G. 

Dinwiddie, analyst; personal communication. The analysis also showed Fe203 , 2.92; 

H20 below 110° C, 0.03; H20 above 110° C., 0.57. The FeO of the analysis gave an
U. S. GEOLOGICAL SURVEY BULLETIN 683 PLATE XIII

A. HUBNERITE FROM THE DRAGOON MOUNTAINS, ARIZ. 

Section showing zonal structure. X 5.

PHOTOMICROGRAPH OF GRANITE FROM WHETSTONE MOUNTAINS, ARIZ. 

Showing wolframite (black) with warty protuberances of scheelite. X 90.
U, S. GEOLOGICAL SURVEY IULLETIN 583 PLATE XIV

WOLFRAMITE FROM IRISH CREEK, VA. 

Section showing interstitial scheelite. X 30.
COMPOSITION OF FERBERITE AND OTHER MEMBERS OF SERIES. 31

the wolframite series Continued.

No.

53

54

55 

5657*'

58

59 

60 

61P,*L

( i?

63 

64 

65

IB

o. .

. Recalculated analysis. ;

W03 .

76.4 

76.4 

76.4 

h 76.4

"-' ' 76.4

76.4

76.4 

76.4 

76.4 

$)* 76.3

76.3 

76.3 

76.3 

 76.3 

& 76.3

FeO.

16.6 

16.9

16.9 

17.2

17.2

17.7

18.1 

18.3 

18.3 

18.6

18.6 

18.7 

18.8 

18.9 

18.9

MnO.

7.0 

6.7

6.7 

6.4

6.4

5.9

5.5 

5.3 

' 5.3 

5.1

5.1 

5.0 

4.9 

4.8 

4.8

FeWOi.

70.1 

71.4

71.4 

72.5

72.5

74.6

.76.6 

77.2 

77.4 

78.3

78.3 

78.8 

79.2 

79.4 

79.6

MriWO<.

29.9 

28.6

28.6 

27.5

27.5

25.4

23.4 

22.8 

22.6 

21.7

21.7 

21.2 

20.8 

20.6 

20.4

Excess 

FeO.

0.4 

.1

.4

.2

'2.0

4.3 

2.1 

.6 

2.8 

1.2

1.1 

.2 

.7 

.5 

.4

Excess 

W03 .

-

CaWO4 .

4.1 

2.1

1.0

5.4

1.7 

2.1 

3.3 

21.1

3.6

Specific 

gravity.

6.70

7.496

7.51 

7.228 

7.513

excess of 0.2 and to this has been added 2.6, the equivalent of the Fe203 given. In 

appearance the material is so pure that it is difficult to account for the apparent 

presence of 3.3 per cent of scheelite (CaW04). Possibly the "H20 above 110° C., 

0.57, "should be C02 . '

62. Wolframite from Cash tin mine, Irish Creek, Rockbridge County, Va. Analysis 

by J. G. Dinwiddie. The analysis also shows Fe203 > 4 -°3; FeO, 11.56; H20 

at 110p , 0.12; H20 above 110°, 0.63; Ti02 , 0.02; A1203 » 0.32; C02 , 0.5. The 

Fe203 has been changed to FeO and added to that item. It is extremely difficult to 

make accurate determinations of ferric and ferrous iron in the wolframites, owing to 

the likelihood of part of the iron being oxidized during grinding and difficulties 

inherent in the chemical determination. The change also makes the analysis foot 

up better. The scheelite (CaW04) is very high, (21.1), but specimens of wolframite 

from the locality show many inclusions of scheelite. (See PI. XIV.)

63. Wolframite from Neuhaus Stollberg, Stassberg, Harz Mountains, Germany. 

Analysis by Petzold. Schneider, R., Ueber einen harzer Wolfram: Poggendorf's 

Annalen, 4th ser., vol. 3, p. 474, 1854.

64. Wolframite from the Germania mine, Cedar Canyon, Stevens County, Wash. 

R. C. Welfe of the U. S. Geol. Survey, analyst.

65. Wolframite from Chanteloube, Limoges, France. Kerndt, T., Ueber die Krystallform und chemische Zusammensetzung der naturlichen und kunstlichen Verbindungen des Wolframmetalles: Jour, prakt. Chemie, vol. 42, p. 105, 1847.

66. Wolframite from Harzgerode, Germany. Kerndt, T., Ueber die Krystallform 

und chemische Zusammensetzung der naturlichen und kunstlichen Verbindungen 

des Wolframmetalles: Jour, prakt. Chemie, vol. 42, p. 105, 1847.

67. Wolframite from "Monte Video," country not given, Kerndt, T., Ueber die 

Krystallform und chemische Zusammensetzung der naturlichen und kunstlichen 

Verbindungen des Wolframmetalles: Jour, prakt. Chemie, vol. 42, p. 102, 1847.
32 COLORADO FERBERITE AND THE WOLFRAMITE SERIES.

Analyses of minerals of

No.

68 

69

70

71

72 

73

74

75

76

77

- 78

79

80

81

82

QQ

84

85

Locality.

FEBBEEITE.

Limoges, France ............. 

Traversella, Italy ............

Nagpur, India. ..............

Estremadura, Spain. .........

Neudon, Germany. . .........

Torrington, New South Wales 

Gordon Gulch, Colo. .........

Cave Creek, Ariz.. ...........

Sierra Almagrera, Spain.. . . . .

Kootenay Belle mine, British

Columbia.

Hill City, S. Dak.............

Ivigtut, Greenland ...........

Last Chance, Colo. ...........

Original analysis.

W03 .

76.20 

75.99

51.59

72.93

77.64

76.30

70.73 

61.80

76.28

66.41

73.74

70.11

74.90

70.94

69.06

75.55

75. 19

62.30

FeO.

19.19 

16.29

14.50

22.70

18.76

20.12

18.13 

16.36

20.38

24.31

18.18

23.29

17.75

17.61

25.97

21.31

22.97

19.90

MnO.

4.48 

3.45

2.94

4.10

4.12

4.12

3.64 

3.12

3.80

3.25

3.37

3.02

2.75

2.71

2.17

2.37

1.33

.69

CaO.

"4." 03"

.38

1.64 

. .35

.20

.24

1.75

1.52

1.52

.26

.79

SiO2.

3.40

15.93

6.00

.72

..

1.02

8.70

ii.68

MgO.

0.80

.16

Trace. 

1.71

.07

.42

2.66

.51

.......

Other substances.

P,0.018. ......

Gangue, 5.55.. 

Alj03 , 1.06....

/S, 0.02. .......

\F. trace....... 

(Ta,Cb)2O6,2.20

CbjOs, trace...

Cb206 ,0.76....

A1 2O3 1.34....

Total.

100.67 

99.76

72.45

99.73

100.52 

101.08

99.69 

100.33

100. 73 }.......

99.79

99.90

100.60

99.96

98.72

100. 00

100.25

99.70

68. Ferberite from Limoges, probably from Puy-les-Vignes. (SeeLacroix, A.,Mine'ra' 

logie de la France et de ses colonies, vol. 4, pt. 1, p. 285, footnote, 1910.) Ebelmen, 

J. J., Note sur la composition du wolfram: Annales dea mines, 4th ser., vol. 4, p. 407, 

1843.

69. Ferberite from Traversella, Italy. Bernoulli, F. A., Ueber Wolfram und 

einige seiner Verbindungen: Poggendorf's Annalen, 4th eer., vol. 21, p. 603, 1860.

70. Ferberite from Nagpur district, India. Analysis by Carnegie Steel Co. Quoted 

by Fermor, L. L., Note on an occurrence of wolfram in the Nagpur district, Central 

Provinces: India Geol. Survey Records, vol. 36, pt. 4, p. 309, 1908.

71. Ferberite from Estremadura, Spain. Analysis by Truchot quoted by Mennicke, 

Hans, Die Metallurgie dea Wolfram, p. 18, 1911.

72. Ferberite from Inverell, County Gough, New South Wales. Liversidge, A., 

The minerals of New South Wales, p. 85,1888.

73. Ferberite from Grube Meiseberg, Neudorf, Harz Mountains, Germany. Schneider, R, Ueber die chemische Constitution des Wolfram-Minerals: Jour, prakt. Chemie, 

vol. 49, p. 334, 1850.

74. Ferberite from the Bismuth mine, Torrington, New South Wales. Analysis 

by H. P. White quoted by Carne, J.' E., The tungsten mining industry in New South 

Wales: New South Wales Geol. Survey Min. Res. No. 15, p. 70, 1912.

75. Ferberite from Gordon Gulch, Boulder County, Colo. Analysis quoted as 

having been made by the Colorado Tungsten Corporation. George, R. D., The main 

tungsten area of Boulder County, Colo.: Colorado Geol. Survey First Rept., p. 43, 

1&09.

76. Ferberite from Grube Meiseberg, Neudorf, Germany. Schneider, R., Ueber 

die chemische Constitution des Wolfram-Minerals: Jour, prakt. Chemie, vol. 49, p. 

334,1850. g '

77. Ore from Beaver Creek, Boulder County, Colo. Analysis given by Greenawalt, 

W. E., The tungsten deposits of Boulder County, Colo.: Eng. and Min. Jour., vol. 

83, p. 951, 1907. The analysis also gives: Gold, trace; silver, 1.2 ounces to the ton. 

The item given under Si02 is designated in the original as "Si."

78. Ferberite from Cave Creek, Maricopa County, Ariz., U. S. Nat. Mus. catalogue 

No. 87283. Analysis by Edgar T. Wherry. The mineral is black and opaque. The
COMPOSITION OF FERBERITE AND OTHEE MEMBERS OF SERIES. 33

the wolframite series Continued.

No.

68 

69 

70 

71 

72 

73 

74 

75 

76

77

78 

79 

80

81 

82 

83 

84 

85

Recalculated analysis.

WOS.

76.4 

76.4 

76.4 

76.4 

76.3 

76.3 

76.35 

76.3 

76.4

76.3

76.3 

76.3 

76.3

76.3 

76.3 

76.3 

76.3 

76.3

FeO.

19.1 

19.2 

19.3 

19.3 

19.4 

19.5 

19.7 

19.8 

19.8

19.9

20.0 

20.0 

 20.5

20.5 

21.0 

21.3 

22.3 

22.8

MnO.

4.5 

4.4 

4.3 

4.3 

4.3 

4.2 

3.95 

3.9 

3.8

3.8

3.7 

3.7 

3.2

3.2 

2.7 

2.4 

1.4 

.9

FeWC>4.

80.8 

81.1 

81.5 

81.7 

81.8 

82.1 

83.1 

83.4 

83.6

84.0

84.2 

84.3 

86.4

86.5 

88.7 

89.6 

94.2 

96.1

MnWO*.

19.2 

18.9 

18.5 

18.3 

18.2 

17.9 

16.9 

16.6 

16.4

16.0

15.8 

15.7 

13.6

13.5 

11.3 

10.4 

5.8 

3.9

Excess 

FeO..

0.1 

1.4 

1.5 

4.2

1.1

.8

.8

7.0

5.4

8.7 

.6 

1.0 

2.3

Excess 

W03 .

3.7

3.1

2.4 

5.4

CaWO<.

20.7

2.0 

.6 

1.8 

1,0

1.2 

9.0

7.8

7.8 

1.3

4.1

Specific 

gravity.

7.162 

6.801

7.169 

6.405 

7.334

analysis shows also CuO, 1.34; "Ta20s, approximately 1.50, and Cb206 , 0.70, judging 

from density of oxides." The quantity of tantalic and columbic pentoxides indicated 

is unusually high. The excess W03 shown seems to be combined with part of the 

CuO to form a hydrous copper tungstate new to science. Work is now being undertaken on this mineral. Part of the copper is probably combined with the Si02 aa 

chrysocolla.

79. Ferberite from the Sierra Almagrera, southern Spain. Liebe, K. L. T., Ein 

neuer Wolframit; ein Beitrag zur Mineral-Ghemie:. Neues Jahrb., 1863 p. 645,. The 

analysis also shows A1203 , 1.15; limonite, 1.39; Sn02 , 0.14; G10, trace. The analysis 

as given follows Dana's recalculation after subtracting the limonite (System of 

Mineralogy, p. 985). The specific-gravity determination is stated to have been 

made by Breithaupt.

80. Ferberite from Kootenay Belle mine, Salmo, British Columbia. Walker, T. L., 

Report on the tungsten ores of Canada: Canadian Dept. Mines, Mines Branch, p. 38, 

1909. ..

81. Ferberite from the American Tungsten Co.'s mine, Hill City, S..Dak. Analysis 

made at the South Dakota School of Mines. Quoted by C. H. Fulton in a private 

report on the mine. Traces of Sn02 and S were found. If the quantities given are 

otherwise correct, it seems probable that a part of the substance determined as "Si02 " 

is really CaO; hence the excess of W03 .

82. Ferberite from the Sierra Almagrera, southern Spain. Rammelsberg, C. F., 

Ueber die chemische Zusammensetzung des Ferberits: K. preuss. Akad. Wiss. Berlin Monatsber., p. 175, 1865.

83. Ferberite from Adun-Tschilon, Siberia. Average of four analyses. Beck, W,, 

and Teich, N., Ueber Wolfram und Scheelit aus Fundorten Russlands: Russ.-k. 

mineral. Gesell. St. Petersburg Verh., 2d ser., vol. 4, p. 315, 1869.

84. Ferberite from Ivigtut, Greenland. Analysis by Chr. Christensen. Boggild, 

0. B., Mineralogia Greenland (Saertryke af Meddelelser om Gronland, vol. 32): Mineral, and Geol. Mus. Univ. Copenhagen, Contr. .to Mineralogy No. 6, p. 182, 1905.

85. Ferberite from Last Chance, Boulder County, Colo. Analysis by J. B. Ekeley. 

George, R. D., The main tungsten area of Boulder County, Colo.: Colorado Geol. 

Survey First Rept., p. 42, 1909. 

35659° Bull. 583 14 3
34 COLOBADO FEBBEBITE AND THE WOLFBAMITE SEBIES.

Analyses of'minerals oj

No.

86 

87 

88 

89 

90 

91 

92 

93 

94 

95

Locality.

FEBBEKITE continued.

Clyde mine, Colo.............

Manchester Lake. Colo .......

Wlnnebago mine, Colo .......

Kimbosan, Japan ............

O rlginal anal ysis .' 

W03 .

73.94 

61.15 

73.52

74.13 

72.24

65.88 

71.01 

75.214

60.98

75.47

FeO.

23.85 

19.33 

22.65

23.15 

27.19

24.14 

24.82 

24. 372

19.13

24.33

MnO.

0.67 

.51 

.60

.56 

.57

.37. 

.18

.185

.08

CaO.

0.60 

.38 

.42

1.28

.35 

1.32

.44

Trace.

SiOs.

0.49 

16.10 

1.81

.71

6.45

.71

15.94

MgO.

0.12 

.39

.......

.50 

Trace.

.59

Trace.

Other substances.

A12 03 0.25.... 

A1 203 2.49.... 

A12O3 0. 75 ....

AI2 03 0.46....

A12 03 2.19.... 

A12 03 2.25....

A12 03 3.10....

TajOs, trace....

Total.

99.92 

100.35 

99.75 

100.29 

100.00 

99.88 

100.59 

99.77 

100.26 

99.80

86. Ferberite from Magnolia, Boulder County, Colo. Analysis by J. B. Ekeley. 

George, R. 'D., The main tungsten area of Boulder County, Colo.: Colorado Geol. 

Survey First Kept., p. 42,1909.

87. Ferberite from Clyde Mine, Nederland, Boulder County, Colo. Analysis by 

Ekeley, J. B., The composition of some Colorado tungsten ores: Colorado Univ. 

Studies, vol. 6, No. 2, p. 95,1909.

88. Ferberite from Elsie mine, Boulder County, Colo. Analysis by J. B. Ekeley. 

George, R. D., The main tungsten area of Boulder County, Colo.: Colorado Geol. Survey First Rept., p. 42, 1909.

89. Ferberite from claim near Manchester Lake, Gilpin County, Colo. Analysis by 

J, B. Ekeley. George, R. D., The main tungsten area of Boulder County, Colo.: 

Colorado Geol. Survey First Rept., p. 42, 1909.

90. Ferberite from Puy-les-Vignes, France. Analysis by Nicolardot, quoted by 

Lacroix, A., Mine'ralogie de la France et de ses colonies, vol. 4, pt. 1, p. 282, 1910.. 

The analysis shows a trace of Sn02 .
COMPOSITION OF FERBERITE AND OTHER MEMBERS OF SERIES. 35 

the wolframite series Continued.

No.

86 

87 

88 

89 

90 

91 

92 

93 

94 

95

Recalculated analysis.

WO8 .

76.3 

76.3 

76.3 

76.3 

76.3 

76.3 

76.3 

76.3 

76.3 

76.3

FeO.

23.0 

23.0 

23.1 

23:1 

23.1 

23.3 

23.5 

23.5 

23.6 

23.7

MnO.

0.7 

.7 

.6 

.6 

.6 4 

.2 

..2 

.1

FeWO,.

96.9 

97.2. 

97.3 

97.4 

97.5 

98.1 

99.1 

99.2 

99.6 

100.0

MnWO<. 

3.1 

2.8 

2.7 

2.6 

2.5 

1.9 

.9 

8 

.4

Excess 

FeO.

 2.3 

1.3 

1.1 

1.5 

5.3 

4:5 

4.6 

1.2 

.2 

.8

Excess 

WO3 . CaWO<.

3.1 

1.9 

2.6 

6.6

6.8

2.8

Specific 

gravity.

7.079

6.640

91. Ferberite from the Barker ranch, Nederland, Boulder County, Colo. Analysis 

by J. B. Ekeley. George, E. D., The main tungsten area of Boulder County, Colo.: 

Colorado Geol. Survey First Kept., p. 42, 1909.

92. Ferberite from Winnebago mine, Gilpin County, Colo. Analysis furnished by 

E. M. Green, Rollinsville, Colo. The original gives: FeO, 22.11, and Fe203 , 3.01. 

The ferric oxide has been calculated to its equivalent of ferrous oxide, and this seems 

to accord better with the remainder of the analysis.

93. Analysis of a pseudomorph of ferberite (reinite) after scheelite from Otomezaka 

or Kurasawa, Japan, by F. Kodera. Quoted by Tsunashiro Wada, Minerals of Japan 

(translated by Takudzi Ogawa), p. 77, 1904.

94. Ferberite from Conger mine, Nederland, Boulder County, Colo. Analysis by 

Ekeley, J. B., The composition of some Colorado tungsten ores: Univ. Colorado 

Studies, vol. 6, p. 95, 1909.

95. Ferberite (reinite) replacing scheelite, from Rimbosan, Kei, Japan. Analysis 

by E. Schmidt. Quoted by Luedecke, Otto, Ueber Reinit, K. v Fritsch, Einneuea 

Wolframsaurea Eisenoxydul: Neues Jahrb., 1879, p. 288. '
36 COLORADO FERBERITE AND THE WOLFRAMITE SERIES. 

CONSIDERATION OF THE ANALYSES.

The collection of analyses just given indicates an essentially 

complete series of mixtures of manganese and iron tungstates ranging 

from pure manganese tungstate to pure iron tungstate, with 'the 

possible number of members limited only by the number of specimens analyzed and by the accuracy of the determinations. The 

series is analogous to those of the plagioclase feldspars and the 

columbite-tantalite group. The greatest difference between consecutive analyses in either hiibnerite or wolframite molecules is 5.5 per 

cent, which is found between the wolframites from Lost River, 

Alaska (No. 34), and Vilate, France (No. 35), which contain, respectively, as recalculated, 56.7 per cent and 51.2 per cent MnWO4 , but 

there can be little doubt that analyses of other specimens from these 

or other localities would fall within the gap. It is also probable that 

if the exact quantity of iron and manganese combined as tungstates 

were known, the results would be considerably different. Most 

writers on the'subject have treated the wolframites as definite compounds of FeW04 and MnW04 , bearing relations to each other which 

could be expressed by small whole numbers, but this does not seem 

to be borne out by the analyses. Groups of analyses of wolframites 

from Zinnwald, from the Boulder district, and from the Black Hills, 

all small areas, show a very considerable variation hi the ratio of 

iron and manganese bearing molecules. Those from Zinnwald range 

from 77.0 per .cent to 60.2 per cent MnWO4 , and those from Boulder 

County range from 36.2 per cent to 0.4 per cent MnWO4 . In some 

crystals of hubnerite a considerable variation in color, probably due 

to difference in composition of different zones, can be seen. Were 

it not for the black color of each part, a zonal growth similar to 

that of porphyritic plagioclase feldspars could probably be observed in 

many wolframite crystals. (See PL XIII, p. 30.) As stated in another 

place by W. T. Schaller, no difference in crystal form can be noticed 

between the two ends of the series. If there were a series of definite 

compounds between the two end members, some expression of the fact 

would probably be found in the facial angles.

Attention is called to the number of wolframites whose analyses 

show the presence of tantalum and columbium. It is probable 

that in some analyses, particularly the earlier ones, other substances 

have been determined as these elements, and in other analyses they 

have not been recognized or determined when present. Dr. Eberhard 

showed spectroscopically (p. 18) that columbium was present in a 

specimen of Boulder County ferberite, but he made no test for 

tantalum. Where one element is present, however, the other is 

almost sure also to be there.
DEFINITION OF FERBERITE AND OTHER MEMBERS OF THE SERIES. 37

Tantalum and columbium are common in wolframites and their 

commercial possibilities have been investigated rather extensively. 1 

Mennicke mentions 1.5 per cent as the highest content of the oxides 

known in wolframites, but the ferberite from Cave Creek, Ariz., 

carries 2.2 per cent of the combined Ta205 and Cb205, according to 

Wherry's analysis. The form in which these oxides are present is 

not positively known, but it seems probable that, as suggested by 

Damour,2 they occur as minute particles of columbite. In the 

ferberite of Cave Creek irregularities in cleavage faces seem to be due to 

the presence of small bodies of a different black opaque mineral which 

may be columbite. I hope to do further work upon this subject.

DEFINITION OF FERBERITE AND OTHER MEMBERS OF 

THE WOLFRAMITE SERIES.

The continuity of the wolframite series as indicated by the analyses 

quoted shows that its customary division into hiibnerite, wolframite, 

and ferberite must of necessity be arbitrary. The analysis on which 

the species ferberite is based (No. 79) gives a content of 3.02 per cent 

MnO, equivalent to 3.7 per cent MnO or 15.7 per cent MnW04 after 

recalculation. Great accuracy can not be claimed for the figures 

showing the constituent molecules,-as the material was impure. In 

defining the species it can hardly be held that 3.07 per cent MnO or 

15.7 per cent MnW04 must mark the extreme limit of Mn allowable in 

ferberite. As by common usage the wolframite series is divided into 

three groups, 20 per cent MnW04 seems to be a convenient and 

reasonable limit to place upon the MnW04 allowable in a ferberite, and 

convenience would seem to indicate for hiibnerite a similar limit of 20 

per cent for its content of iron tungstate, FeW04 . For the mixtures 

between these end members the older term wolframite may properly 

be retained, and this term may well serve also as a general or field name 

for the members of the series which can not be definitely identified.

I therefore propose the following definitions for the members of the 

wolframite series:

Ferberite: A monbclmic iron tungstate having when pure the composition FeW04 . It may contain not more than 20 per cent of the 

hiibnerite molecule, MnW04 .

Hiibnerite: A monoclmic manganese tungstate having when pure 

the composition MnW04 . It may contain not more than 20 per 

cent of the ferberite molecule, FeW04 .

1 Mennicke, Hans, Die Metallurgie des Wolframs, pp. 125-130,1911.

2 Damour, A., Surle wolfram tantalifere du d(5partement de la Haute-Vienne: Soc. gdol. France Bull., 

2d ser., p. 108,1848.
38 COLOEADO FERBERITE AND THE WOLFRAMITE SERIES.

Wolframite: A monoclinic mineral containing the ferberite molecule (FeW04 ) and the hiibnerite molecule- (MnWOJ in all proportions between 20 per cent FeW04 and 80 per cent MnW04 , and 80 

per cent FeW04 and 20 per cent MnW04 .

Under this scheme the analyses show ferberites from 13 widely 

separated localities Boulder County, Colo., Cave Creek, Ariz. ; and 

Hill City, S. Dak., in the United States; British Columbia; Greenland; 

France; Saxony; Italy; Sierra Almagrera and Estremadura, Spain; 

New South Wales; India; Siberia; arid Japan. The ferberite of Japan 

was described as reinite and replaces scheelite. From Limoges, 

France (No. 68), is shown a ferberite that contains nearly the maximum amount of manganese. The purest ferberite, showing no 

manganese and only a small excess of iron oxide (0.8 per cent), is 

that from Japan. Minerals from Gordon Gulch (No. 58) and Ward 

(No. 49), in the Boulder tungsten field, fall well within the wolframites, although from the most remarkable ferberite locality known. 

They merely 'emphasize the characteristic variability of the hubneriteferberite mixture.

EXCESS OF FERROUS OXIDE AND MANGANOTJS OXIDE,

A point to which considerable importance has been attached by 

different writers is the excess of FeO in the ferberites, .but the table 

of analyses shows that they are not unique in this, though some 

ferberites do carry large excesses of FeO.

The proneness of W03 to form a lower oxide on heating and its 

solubility make it seem probable that many determinations of the 

oxide are low, so that the appearance of an excess of 0.1 or 0.2 per 

cent FeO may be neglected. It is also probable that in many of the 

analyses the MnO is too high, a common error when the determination is made gravimetrically, and a- very small excess of MnO would 

cause a somewhat larger apparent excess in the FeO. Only a few 

of the analyses show the presence of alumina, but many wolframites 

occur in a gangue. containing muscovite or feldspar or both, and 

small quantities are likely to be mixed with the mineral analyzed. 

If the mineral is fused, the alumina, unless specially separated, will 

be precipitated with the iron oxide, and, if the iron is determined 

gravimetrically, will by so much make it appear larger.

Iron oxide is commonly present as such, for in the oxidized zone the 

breaking down of minerals such as siderite, pyrite, chalcopyrite, or wolframite setsfree iron oxide, which mayformfilms over the residual wolframite or fill cavities of microscopic or larger size. A cut and polished 

crystal of brown ferberite from the Winnebago claim near Rollinsville shows a very porous structure (see PL IV, A, p. 13) and the 

cavities are coated with hydrous iron oxide. This material is similar 

to that found on part of the Rogers tract and would surely give a
EXCESS OF FERROUS OXIDE AND MANGANOUS OXIDE. 39

considerable excess of iron on analysis. Specular hematite or 

magnetite, in particles too small to be easily distinguished, may occur 

in the ore, and the presence of one or both of these minerals may 

account for the surplus iron shown in some determinations.

In those wolframites which contain tantalum and columbium 

columbite may furnish a part of the apparent excess of iron. Microscopic examinations made by reflected light on polished and etched 

specimens of clean black ferberite show none of the differences in 

texture to be expected if such other minerals were present. There 

are, however, minute cavities which may be partly filled with iron 

minerals.' Manganese dioxide, though in less quantity than iron 

oxides, is commonly associated with the ores, but its presence on the 

lighter-colored hiibnerites should be easily distinguishable. The 

possibility of FeO and MnO being held in solid solution in the minerals 

of the wolframite series suggests itself, but no proof of this has been 

found.

It is to be noted that if the analyses given had been recalculated 

by first satisfying the FeO with W03, and then combining the 

remainder of the W03 with the MnO, the excess of the FeO would 

disappear in most of the analyses and there would be an excess of 

MnO. However, as just stated, manganese oxide occurs with the 

wolframites in much less quantity than iron oxide, and for this reason 

in recalculating an analysis it is best to first satisfy the MnO with 

W03 . It appears, therefore, that though some of the wolframites 

may carry an excess of FeO, and a few an excess of both FeO and 

MnO, most if not all of the apparent excesses are due to impurities 

present in the material analyzed and to errors of analysis.

Many careful analyses of well-selected minerals and many examinations by metallographic methods must be made before a real excess 

of FeO or MnO in the wolframites can be demonstrated.
CRYSTALLOGRAPHY OF FERBERITE FROM COLORADO.

By WALDEMAR T. SCHALLER.

PREVIOUS PUBLICATIONS.

The several papers mentioned by Mr. Hess in his part of this report 

give some general facts in regard to the habit and size of crystals of 

ferberite. Two other papers, by Warren and by Moses (see Bibliography, pp. 74-75), give descriptions of ferberite crystals which may 

have come from this locality. The crystal figured by Warren is said 

to have come from South Dakota, though he states that the exact 

locality could not be ascertained. From the appearance of the crystal 

it is more likely to have come from Colorado than from South Dakota. 

The crystal figured and described by Moses as crystallized wolframite 

from Boulder County, Colo., is very similar to those here described.

These two papers are the only publications on the crystallography 

of the ferberite from Colorado that could be found.

GENERAL CHARACTER OF THE CRYSTALS.

MODE OF OCCURRENCE.

In the specimens examined the ferberite crystals are perched on 

the country rock in groups or they line or nearly fill the cavities or 

fisgures in the matrix. Layers of ferberite several centimeters thick, 

consisting of crystals whose bases have coalesced, are found on the 

rock. Much of the ferberite, which at first glance seems to be massive, is found on closer inspection to be a granular compact mass of 

small crystals.

The crystals occur isolated as distinct individuals (Pis. VII, p. 18, 

and VIII, p. 19), in groups of parallel or nearly parallel individuals 

(Pis. IX, p. 20, and X, p. 21), or in confused masses consisting of 

numerous abutting and even penetrating crystals. Twins are common, though single untwinned -crystals are far more plentiful. The 

nearly parallel groupings are of two kinds: (1) A group of flattened 

crystals which may depart several degrees from strict parallelism and 

which are joined by the a(100) faces (fig. 1); and (2) crystals joined 

by the c(001) faces and superposed, the line of demarcation of the

40
GENERAL CHARACTER OF THE CRYSTALS. 41

different crystals being well shown by the irregular lines crossing 

the prism zone normal to the vertical striations (fig. 2). The distribution of the dome faces on several of the parallel groupings joined by 

the a (100) face conclusively demonstrates that the 

crystals are not twinned. 

Well-developed crystals are abundant, but 

many crystals are rounded 

and curved either in a 

single zone or throughout^ 

The curving of the surfaces in a single zone is 

generally due to the 

marked development of

the striations in the prism

zone. (See fig. 9, p. 59.)

The curving of the faces

over an entire crystal is

due to the nearly parallel

grouping of a number of crystals, each one deviating successively a

little more from parallelism with the original unit.

The various forms of occurrence of ferberite found on the specimens 

examined may conveniently be summarized as follows:

1. Massive.

2. Bladed, indistinctly crystallized.

3. Distinct.individual crystals.

a, Single well-formed crystals (Pis. 

VII, VIII, XI, and XII, 

and text figs. 3-34). 

b, Twinned crystals (PI. VIII,A, and 

text figs. 14,15,17, and 18). 

c, Crystals grouped in parallel position (Pis. IX and X).

(1), Composition face a(100) 

(fig-1).

(2), Composition face c(001)

(fig. 2). '

d, Rounded crystals or groups of 

crystals.

FIGUBE 1. A, Orthographic projection of crystals with similar 

combinations in parallel grouping, joined by the a(100) face; 

B, Orthographic projection of two crystals with dissimilar 

combinations. The cleavage parallel to 6(OlO) in many crystals terminates one side. Forms: c{001>, 6{010>, o{100>,

FIGURE 2. Superposed crystals, joined by 

the c(001) faces. The line of demarcation 

is normal to the vertical striations on the 

large a(100) faces.

SIZE.

In size the crystals vary considerably. The largest seen were about 

1.5 centimeters long (6 axis), half as high (c axis), and about 4 millimeters thick (a axis). The general average would be about 5 to 10 millimeters long, 2 to 5 millimeters high, and 1 to 3 millimeters thick. On
42 . COLORADO FERBERITE AND THE WOLFRAMITE SERIES.

some of the rock specimens areas extending over many square centimeters are coated by minute crystals, few of which measure more than 

a millimeter in any direction, Most of the crystals measured were, 

much smaller than the average. The dimensions of the crystals were 

accurately measured under the microscope, so that their proportions 

might be shown in the drawings for. the text figures in this bulletin. 

Of 18 crystals thus accurately measured the a axis lay between 0.3 and 

0.7 millimeter on 14 crystals; the 6 axis (which in most of these crystals has about half the true original value) between 0.5 and 2.5 millimeters on 16 crystals; and the c axis between 1.0 and 3. 5 millimeters 

on 13 crystals. The extreme values are: a axis, 0.3 to 5.0 millimeters 

(the 5.0 is an extreme value, the next highest is only 1.5; all the other 

values are less than 1.0 millimeter); & axis, 0.6 to 3.2 millimeters; c 

axis, 0.3 to 3.8 millimeters.

Most of the crystals measured were bounded on one side by a cleavage face of 6(010), so that .the sizes here given do not actually represent the size of the original crystals in the direction of the 6 axis. In 

the illustrations (figs. 3 to 34) the crystals are generally shown relatively longer in the & axis than the measured values indicate, in order 

to represent more truly their actual original sizes. The & axis on 

many of the complete crystals was probably twice as great as 

measured.

COLOR AND CLEAVAGE.

The crystals are black and their luster is splendent, nearly metallic. 

The streak is dark brown, suggesting hematite. It is distinctly not 

black. Cleavage is clinopinacoidal, &{010}, very good, and commonly 

visible on the basal pinacoid.

THE MEASURED CRYSTALS BY LOCALITIES.

In the following table the crystals measured are grouped according 

to the mine from which they came. In addition their general 

character and habit are given for reference. These descriptions and 

localities are based entirely on the material collected by Mr. Hess; 

For other localities, not mentioned here, the papers given by Mr. Hess 

in his bibliography should be consulted.
AXIAL ELEMENTS. 

List of crystals by localities.

43

Crystal 

No.

1 

2 

3

4

5 

6 

7

8

9 

10

11 

12

13 

14

15,

16 

17

18 

19 

20 

21

m,

23

24 

25 

26 

27

28

29 

30

31

32 

33 

34

35

' 36 

37

38

Locality.

.

Crystals 1-12 from 1 .specimen of ore from the 

100-foot level of the Hoosier mine, Boulder County,

Crystals 13-17 from 1 specimen from the Nugget

claim, 5 miles southeast of Ne'derland, li miles

Specimen taken from a 17-foot winze.

mens, all from the sam < claim as crystals 13-17

mine, Nederland, Boulder County, Cplo.

[ From Black ITawk claim, Boulder County, Colo....

From Georgia A. vein, 2 miles northeast of Nederland, 

Boulder County, Colo.

Illustrated in 

figure 

. 4 

11

10 

22 

23

24

14

25

26 

27

28 

29 

30

13 

33 

34

19

20 

21

I 31 \ 32

6

Original 

notebook No.

Ai 

A2 

A3

A< 

A5

Ac 

A7

As

A9

An

B! 

B2

B3

B< 

Bo

Ci-1 

C,-2 

Ci-3 Ci-4

Ci-5

Ci-6

Cz-1 

. Cz-2 

Cr-1 

Cs-2

Cir3

D, 

D,

D3

D4 

D5

Do

D7

Ei

E3

F

Description and habit."

S, prismatic. 

S, wedgelike.

S, wedgelike. 

S, prismatic. 

Do. 

Do.

S, prismatic. 

T. tabular.

Do. 

Do.

S, prismatic. 

Do.

Do.

G, prismatic. 

S, prismatic.

Do.

Do. 

0, prismatic.

Do. s

T, tabular.

S, rhombic. 

Do. 

Do.

S, wedgelike. 

Do.

Do.

Do. . 

Do. 

Do.

Do. '

S, cubic. 

Do.

Do.

<»S, simple crystal; G, group of crystals in nearly parallel position; T, twin crystal.

AXIAL ELEMENTS.

The discussion of the axial elements of ferberite leads at once to the 

question of the relation of ferberite to the wolframite group.

In this connection a consideration of the relation in angular values 

between the pure iron tungstate and the pure manganese tungstate 

is of interest. The ferberite crystals at hand did not yield results as 

satisfactory as had been expected, because of the imperfection of the 

crystals, due to striations, parallel groupings, and like features; 

because of the scarcity of well-developed terminal forms; and because 

the high polish of most of the crystals had been destroyed by the 

hydrofluoric acid used to remove the matrix and clean the crystals.

CALCULATION OF VALUES.

Below are given the best measurements obtained that are suitable 

for the calculation of the axial elements, and these are compared with 

the measurements given in the literature for the members of. the.
44 COLOBADO FEBBEBITE AND THE WOLFBAMITE SEBIES.

wolframite group. All measurements were made with a Goldschmidt 

two-circle goniometer.

Average of best measurements.

(010).: (110)

Fair reflection: 

50° 16'

22

23

12

24

20

22

16

15

Poor reflection: 

50° 31'

27 '

28

22

17

20

21

Average of 9 measurements with fair

reflection, 50° 19'. 

Average of 7 measurements with poor

reflection. 50° 24'. 

Average of the 16 measurements, 1

50° 20£'.

(001) : (Oil)

Good reflection: 

41° 00'

01

00 

40 59

59

57

5.7

58

56

53

56

Average of 11 measurements, 40° 58'.

(010) : (210)

Good reflection: 

67° 2.7'

23 

.24

26

25

31 .

25

32

21

Fair reflection: 

67° IT 

23 

16 

28 

19 

27 

30 

26

Average of 9 measurements with good

reflection, 67° 26/. 

Average of 8 measurements with fair

reflection, 67° 23'. 

Average of the 17 measurements, 1

67° 25'.

(001) : (102)

27° 46'

49 

27 43 

45 

37 ' 50

Average of 6 measurements. 27° 46/. 

(001) : (100)

89° 507 

34"

32

33

Average of 4 measurements, 89° 37'.

In the measurements of the prism angles the <f> angle was obtained, 

this being the same as the angle (010) A prism. The v0 or zero

i Good measurements weighted twice as much as fair ones; fair measurements weighted twice as much 

as poor ones. ...
AXIAL EL-EMENTg. 45

reading on 6(010) was averaged for each crystal from the readings 

obtained on (010) and (OlO) (often a cleavage face), and from the average of (110) and (HO), and (210) and (2lO), respectively. The 6(001) 

faces were generally striated in the zone (001) : (100), but this in 

nowise interfered with the accuracy of the measurement of the angle 

(001) : (Oil). The accurate measurements from (001) to (102) and 

to (100) were very few in number, as the base (001) was striated in 

this direction on most of the crystals.

COMPARISON- OF VALUES.

Instead of deriving axial elements from these angular values I 

have compared the interfacial angles directly with the best ones 

I could find in the literature for the entire wolframite group. These 

have been arranged in order of decreasing percentage of MnO, so 

that the first lines in the table below represent hubnerite and 

the last lines (except the very last) represent ferbeiite. The very 

last line contains the values taken from Goldschmidt's Winkeltabellen, in which the axial elements of Descloizeaux, Krenner, 

and Seligmann have been averaged. (See Bibliography, pp. 74-75.) 

A careful study of the angular values given in any column 

does not show any regular' increase or decrease corresponding 

with the regular decrease in percentage of MnO. In fact the variation in angular values for two or more wolframites of nearly the same 

composition is nearly as great as between the extreme end members. 

The correlation of the chemical composition and the crystallographic 

constants is doubtful in so far as the analytical figures given were 

not obtained on the material actually measured.

Comparison of angles with variation in chemical composition.

Locality and

material.

MnW04 (artificial).

Mn2Fe3 (WOO»

(artificial).

FeWO4 (artificial).

runi. 

.....do..........

Penfield.........

runi.

Seligmann ......

W. T. Schaller..

Groth and Arzruni.

Winkeltab e 1- 

len.

Per

MnO.

23.4

22.24

21.93

9.4

4.96

4.84

3.15

.1.0-

(010):(110).

50 15

50 27k

50 06

. 50 21

5030

50 18*

5036

50 20*

5033

50 27

(010):(210).

0 ,

67 19

67 36

67 28

67 40

67 25

07 34*

Angle.

(001):(011).

0 ,

40 55

40 51J

40 42J

40 57

41 03J

40 58

40 54

(001):(102).

27 12i

27 29

27 2?$

27 50J

27 46

27 33

27 35

(001):(100).

0 1

89 07i

8939*

89 21}

89 34

8937

89 32

Computed from axial elements of Descloizeaux, Krenner, and Seligmann.
46 COLORADO FERBERITE AND THE WOLFRAMITE SERIES.

A definite, measured difference in crystallographic constants between ferberite (FeW04) and hubnerite (Mn04) is not shown by the 

table just given. The ,average axial elements given by Goldschmidt 

represent closely the angular values for the different members of the 

wolframite group. These values are also close to those obtained on 

the Colorado ferberite as shown below.

Comparison of angles of ferberite from Colorado with the values given in Goldschmidt's

Tables.

Angle.

(010):(110),......

(010):(210).......

(001):(011).......

(001):(102).......

(001):(100).......

Goldschmidt's 

Winkeltabellen.

50 27

67 34

4054

27 35

89 32

Boulder 

County 

ferberite.

50 204

67 25

40 58

27 46

89 37

Difference.

-06J

-09

.+04

+11

+05

The axial elements given by Goldschmidt, namely, a: &:c = 0.8255: 

1:0.8664, /? = 89° 32', therefore best represent the constants for the 

entire wolframite group.

The data for the percentages of manganese given in the table on 

page 45 have been taken from Dana.1 Descloizeaux's measurements 

were made on material from Vilate, near Chanteloube (HauteVienne), France. An analysis of wolframite from Chanteloube shows 

4.84 per cent MnO and 19.32 per cent FeO. Krenner's measurements 

were made on crystals from Ehrenfriedersdorf, Saxony, and an analysis of material from the same locality shows 4.96 per cent MnO and 

19.16 per cent FeO. Seligmann's ferberite from Sierra Almagrera, 

Spain, contains 3.15 per cent MnO arid 19.95 per cent FeO, according 

to Doelter.2 Two confirmatory analyses of the Spanish ferberite 

show 3.00 and 3.02 per cent MnO with high FeO. Hubnerite from 

Colorado 3 showed 21.93 per cent MnO and 2.91 per cent FeO. 

"Megabasite" from Schlaggenwald contained 22.24 per cent MnO 

and 3.74 per cent FeO.

FORMS AND ANGLES.

A total of 32 forms were determined on the ferberite crystals from 

Colorado. Of these 12 are new for the wolframite group. These 32 

forms are given in. the table below with the measured and calculated coordinate angles. The new forms are marked with an 

asterisk (*).

1 Dana, E. S., System of mineralogy, 6th ed., p. 984,1892.

2 Zeitschr. Kryst. Min., vol. 11, p. 348,1887.

8 Penfleld, S". L.; see Dana, E. S., op. cit., pp. 983,984.
NEW FORMS. 47

List of forms and angles onferberite crystals. 

[New forms are marked with an asterisk.]

No.

1

2

3

4

5

0

7

8

9

10

11

12

13

14

15

' 10

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

Letter.

c

b

a

T

771

z

*R*c

*F

Q.

d'

*0

*M

*N

J

*L

n

f

u

t

*n

r*j?

*E

<a

A

*A

V

*D

s

e

 o

Symbol.

Goldschmidt.

0

Ooo

ooO 

oo2

00

2oo

Voo

loo $00

foo

3oo

ico

5 oo

y oo

C oo

Too

800

01

+ } 0

+ JO .

+ 1 0

-WO

+ i ?

+AA

+ 1

+ *

+ f

+ H

+ 1 1

-12

- i

- 1

Miller.

001

010

100

120

110

210

15.7.0

940

520

830

310

720

510

11.2.0

610

710

810

Oil

104

102

904

1. 0.11

123

5.9.14

111

112

337

214

313

121

' 112

111

Measured.

<t>

90 00

 0 00

90 12

33 49

50 21

67 25

69 00

7001

71 39

73 19

74 47

7645

8030

81 35

82 00

83 08

84 20

0 04

9000

90 00

9000

90 00

31 10

34 25

50 25

50 16

50 45

69 42

74 21

30 14

50 16

50 26

.P

0 23

90 00

9000

9000

9000

90 00

90 00

9000

90.00

90 00

90 00

9000

: 9000

90 00

90 00

90 00.

90,00

40 54

1628

27 46

66 31

4 20

34 13

33 48

53 45

34 24

30 37

31 22

47 21

63 45

34 27

53 48

Calculated.

<t>

90 00

000

90 00

31 12

50 27

67 31

6856

69 51

71 44

72 48

74 37

76 44

8038

SI 28

82 10

83-16

84 06

0 32

9000

9000

90 00

90 00

31 47

34 31

50 40

5053

5058

6753

74 44

31 00

50 01

50 14

p

0 28

90 00

90 00

90 00

90 00

90 00

90 00

90 00

90 00

90 00

90 00

9000

9000

90 00

90 00

90 00

90 00

4054

15 08

28 03

67 07

4 59

34 12

34 03

53 49

34 29

30 31

29 55

47 38

. 03 41

33 59

53 34

NEW FORMS.

A somewhat detailed description is given of the new forms found 

on the crystals. They may be grouped as follows:

Groups of new forms onferberite crystals.

New prisms............................... 7

New positive domes...................... 1

positive pyramids.................... 4

Measurements of *R {15.7.0}.

12

Crystal 

No.

23

31

18

Reflection.

Fair...........

Fair...........

Size efface.

.....do.........

.....do.........

* (calculated 

68° 56').

68 57

68 49

69 14
48 COLORADO FERBERITE AND THE WOLFRAMITE SERIES.

On crystal 23, the new form, R, lies between Z{210} and Q{830} as 

a very narrow face, giving a distinct signal. The faces measured in 

one-half the prism zone are (010), (110), (210), (810), (100); (010), 

(110), (210), (15.7.0), (830), (TOO).

. On crystal 31, three faces lying very close together gave good 

signals, and the measurements showed the presence of the three forms 

Z{210}, #{15.7.0}, and £{940}.

On crystal 18 a part of the prism zone (see description of <7{940}, 

crystal 18) showed the forms #{830}, <7{940}, #{15.7.0}, and ZJ210}.

In all the three occurrences of R{ 15.7.0} the form is associated with 

Z{210} and in two of them it lies between Z{210} and 6"{940}. From 

these facts, as well as the close agreement in measured and calculated 

values, the form is considered as definite and well established.

Measurements o/*C{940}.

Crystal No.

18

31

1

Reflection.

Fair...........

Good..........

Poor..........

Size of face.

.....do.........

* 

(calculated 

69° 51').

C9 -19

69 53

70 21

On crystal 18 the form was one of three faces lying close to Z{210} 

and between it and a{ 100}. They form alternating narrow faces, but 

the signals they gave were clear and distinct. The faces were not 

striated. The prism zone-is incomplete, the piece measured being 

only a fragment of a crystal. The other three forms present in the 

zone are #{830}-, #{15.7.0}, and Z{210}.

On crystal 31 the three forms Z{210}, #{15.7.0}, and <7{940} .lie 

close together and form alternating nonstriated faces similar to those 

observed on crystal 18. The other parts of the prism zone are not 

measurable, so that the presence on this crystal of other faces of the 

last two forms could not be confirmed.

On crystal 1 the form was noted once as a line face between a(100) 

and a cleavage face of &(OlO). On other parts of the crystal the 

form was absent.

Measurements of *F{ 520}.

Crystal 

No.

1

22

Reflection.

Poor..........

.....do........

Size of face.

.....do....:...

* 

(calculated 

71° 44').

71 55

71 23
NEW FORMS. 49

On crystal 1 the new prism was noted once with the forms a{100}, 

?>i{110}, Z>{010}. On crystal 22 the portion of the zone with the new 

prism was richer in faces, chose present being 6(010), m(TlO), Z(210), 

F(520), a (TOO). The new form F is considered as established, 

though the agreement between the angles is not so good as for the 

two more complex symbols just described.

Measurement of *(7{720}.

Crystal No. 14.

(calculated 

76° 44').

76° 45'

The new prism G was observed only once as a narrow face yielding 

a fair reflection. It formed one of four faces lying very close together, 

pach of which, however, gave a distinct signal. These four faces, 

lying between m(110) and a(100), are $(720), a face near (410) but 

not determinate, JW(510). and N(l 1.2.0).

Measurements of *M{ 510}.

Crystal 

No.

13

1

14

Reflection.

Good.........

Poor..........

Fair..........

Size of face.

.....do........

.....do........

^ 

(calculated 

80° 38').

80 21

80 58

80 12

The new prism M is always -associated with-several other rare 

prisms. Narrow faces of it were found on crystal 13 with ?i(810), 

«(100), 7i(8TO), l/(5lO); on jjrystal 1. as a striated face with &(010), 

m(110), F(520), a(100), J/(5lO), Z(2lO), m(lTO), and &(OlO); and on 

crystal 14 with $(720).

Measurements of *N{ 11.2.0 /.

Crystal 

No.

14

14

17

Reflection.

 Fair..........

.....do........ 

.....do........

Size of face.

.....do........

<t> 

(calculated 

81° 28')-

81 20

81 31

81 48

The two faces of N on crystal 14 are both narrow and both occurred 

with other prisms, but each with different forms. With one of them 

the associated forms were ra(TlO), $(720), a face near (410), J/(510), 

JVCIT.2.0) and a(TOO); with the other the forms were n(8TO), £(710), 

and JV(TT.2.0). On crystal 17 N occurred with a(100), »(810), and 

7(210), being broader than either Z or n. 

35659° Bull. 583 14 4
50 COLORADO FERBERITE AND THE WOLFRAMITE SERIES. 

Measurements of *L{710}.

Crystal 

No.

14

5

5

Reflection.

Fair..........

Poor..........

Fair..........

Size of face.

Narrow .......

.....do........

* 

(calculated 

83° 16').

83 19

83 11

82 55

The occurrence of L{7W} on crystal 14 has already been noted 

under N{II.2.0}. On crystal 5 it is present twice as broad faces, in 

each case unaccompanied by other rare prisms and forming the only 

face between a(100) and 1(210).

Measurements of*H{Q04}.

Crystal 

No.

13 

14 

24 

15 

16 

19 

28 

31 

26 

34 

20 

27

Reflection.

Poor..........

.....do........

.....do........

.....do........ 

.....do........

.....do........

.....do........

Size of face.

Line face. ..... 

.....do........

.....do........ 

.....do........

.....do........ 

.....do........

.....do........

.....do........

.....do........

.....do........

.....do.........

.....do........

P (calculated 

67° 07')-

a 

a 

a 

a

6706 

67 13 

67 38 

66 

67 

66 

69 

68 

b) 

(A

6)

o Approximate. & Not measured.

This new dome, always present as a line face, was noted on 12 

crystals, as shown in the table. The reflections from the faces were 

either very poor or not discernible, so that the approximate measurements (expressed only in degrees) were made by using the position 

of maximum illumination. The form is near to the simpler one 

{201}, but the measurements show that {904} are the correct symbols. 

The calculated p angle for the form {201} is 64° 37'.

Figures 25, 26, 29, 30, 33, and 34 show the new form #{904}.

Measurements of *B {123}.

Crystal 

No.

13 

19

Reflection.

Poor.......... 

.....do........

Size of face.

Small.........

0

(calculated 

31° 47').

31 22 

30 58

p (calculated 

34° 12').

34 21 

34 05

On crystal 13 the small face of B gave a poor but distinct reflection.

The occurrence is illustrated in figure 25 (p. 66), an ideal representa-

'
NEW FORMS. 51

tion of the crystal, which shows two faces of the form. The second 

side of the crystal is, however, not present, as a cleavage face of (010) 

terminates that side of the crystal. On crystal 19 the form 5(123} 

is represented by a line face lying between £"{5.9.14} and/{Oil}, 

both of which are larger than B. This occurrence is represented in 

.figure 29 (p. 67). The form is probably also present on crystal 20, 

where a nonmeasurable line face was observed between J{112}. and 

/{Oil}, though it could not be determined whether the form -was

{123} or {5.9.14}.

Measurements of *E{ 5.9.14}.

Crystal 

No.

19

20

27

Reflection.

.....do........

.....do........

Size of face.

'Small.........

.....do........

<£ 

(calculated 

34" 31').

34 21

34 20

34 35

(calculated 

34° 03').

33 50

3402

33 31

The first two occurrences of £"{5.9.14} are small faces, much wider 

than the usual line faces and, as shown in figure 29 (p. 67), the face 

on crystal 19 reaches a fair size, whereas the corresponding simpler 

form jB{123} is present as a line face. On crystal 20 (fig. 30, p. 68) 

the small face of £"{5.9.14} lies between J{112} and/{Oil} and also 

attains an appreciable size. On crystal 27, however, it is present as 

a mere line face.

The symbols for the form E are rather complex and unusual, but 

the identification of the form on three crystals, the small distinct 

faces, and the close agreement between measured and calculated 

angles show that the form is well established.

Measurements of * A { 337}.

Crystal 

No.

13

15

20

21

Reflection.

.....do........

.....do........

.....do........

Size of face.

.....do........

.....do........

.....do........

<£ 

(calculated 

50° 58')-

50 47

51 00

51 00

50 13

p (calculated 

30° 31').

31 08

30 12

3005

31 03

The form A is characteristically a line face between c{001} and 

J{112}. The only forms in this zone observed on these crystals are 

m{110}, w{lll}, J{112}, ^{337}, c{001}, e{Tl2}, and o{Tll}. The 

form is shown in figures 25 and 30 (pp. 66, 68). 

' *D{313}. Only one face of this new form was observed, this 

being on crystal 19, where a small face yielded a fair reflection 

whose measurement gave 0, 74° 21' (calculated 74° 44').; p, 47° 21' 

(calculated 47° 38'), The form is shown in figure 29 (p. 67).
52 COLORADO FERBEEITE AND THE WOLFEAMITE SEMES.

FORMS PREVIOUSLY DESCRIBED. 

COMMON FORMS.

The common forms merit only a brief description, as their relative 

development and occurrence can well be seen by studying the drawings illustrating the different combinations and habits.

In the prism zone the orthopinacoid a{100} is always strongly 

striated vertically. These striations are not shown in the crystal 

drawings. The orthopinacoid is often replaced by vicinal forms several degrees from the true position of a{100}. On other crystals 

the faces of 0(100} are very close to their true position of 90° 00'. 

No connection could be traced between the presence of vicinal forms 

replacing a{100} and the presence of new or rare prisms, as the 

following table shows:

Measurements of a{100} and list of associated prisms.

Crystal 

No.

1

3

4

5

7

8

10

13 

14

22

23

32

34

35

*

/90 06 

\90 55

86 00

86 57

f90 07 

\87 47

/87 02 

\88 ' 35

87 38

/90 06 

190 11

89 53 

90 49

86 49

88 15

89 30

f88 24 

\88 22

/88 26 

\86 45

Remarks.

}{120}, {940}, {520}, {510} present.

No new or rare prisms present.

.Do.

<810>, {710} present. 

{710} present.

>No new or rare prisms present.

Do.

} Do.

{810}, {510} present. 

{720}, {510}, {11.2.0}, {810}, {71(1}

present.

{810}, {520} present.

{810}, {15.7.0}, {830} present.

{810} only rare prism present.

}NO new or rare prisms present.

} Do.

The common prisms Z{210} and m{110} are striated on some 

crystals and free from any strise on others, those without striae 

yielding good and distinct reflections.

The base c{001} is generally rounded in the zone {001}:{100} 7 

commonly giving several reflections, the extreme ones on some crystals being several degrees apart.

The faces of /{Oil}, generally small, all gave good and distinct 

signals; those of £{102} were generally distinct, although on a few 

crystals they were somewhat blurred.

The pyramids are generally so small that the reflections from their 

faces are faint. The striations on J{112} cause the large faces of 

this form to yield indistinct and blurred signals. The striations are 

shown in figure 28 (p. 67).
FORMS PREVIOUSLY DESCRIBED. 53

RARE FORMS.

A number of rare forms which were observed on these crystals 

are entitled to a short discussion. The results are also applied to 

the tabulation of the forms of the wolframite group as developed on 

a later page.

r{120}, already no ted by Descloizeaux and Jeremejew,1 is probably 

present as a line face on crystal 1.; <-/> measured 33° 49' (calculated 

31° 12').

Q{830}, found by Penfield on hubnerite from Colorado,2 is verified 

by the presence of two line faces on the crystals herein described,. 

On crystal 18 a line face yielded a fair reflection whose measurement 

gave (j> a value of 73° 06' (calculated 72° 48'); crystal 23 showed a 

very narrow face, the measurement of whose reflection gave 0 a 

value of 73° 32' (calculated 72° 48'). Penfield's 2 letter # was 

changed 3 to Q, as q had already been preempted by the form {103}.

<Z{310}, noted by Krenner, Boggild, and as doubtfully present 

by Moses, was found once on crystal 9 as a very narrow face, giving 

a poor reflection. <j> measured 74° 47' (calculated 74° 37'). The 

occurrence is illustrated in figure 24 (p. 66).

j{610} was first described by Boggild, who assigned to the new 

form the letter p. As this letter had been used by Moses to designate the form {214}, I have changed Boggild's p to j, as here given. 

The form was noted once, on crystal 9, as a medium-sized striated 

face; $ measured about 82° (calculated 82° 10'). The form is shown 

in figure 27 (p. 67).

n{SlQ}, first noted by Groth and Arzruni, has been observed a 

number of times on these crystals. Some occurrences are shown in 

figures 22, 25, and 27. The angles measured are as follows:

Measurements of n{ 810}.

Crystal 

Xo.

5

13

14

17

32

Reflection.

Fair...........

.....do. .......

.....do........

.....do........

.....do........

Size of face.

Large.................... ...

.....do...:..................

Narrow and striated.........

<t> 

(calculated

84° 06').

84 13

83 50

84 23

84 52

84 20

-u{104}, observed only by Jeremejew, is confirmed by finding it on 

crystal 13 as a.line face with £(102) a.nd 77(904), as shown in figure 25 

(p. 66). The reflection was very poor and its measurement gave p 

16° 28' (calculated 15° 08').

1 See Bibliography, pp. 74-75, for references.

2 Dana's System of mineralogy, Oth ed., p. 982. 

8 Goldschmidt's Winkeltabellen, p. 366,1897.
COLORADO FERBERITE AND THE WOLFRAMITE SERIES.

f{T.0.11}, the only negative dome observed on any of these crystals, 

was first noted by Groth and Arzruni and is verified by finding it 

on three of these crystals. The reflections were, however, very poor, 

owing to the rounded and striated character of the faces. For comparison the original measurement of Groth and Arzruni is added to the 

table below. The p angle, as here given, is equal to (001A T.O.I 1) 

(90°-/2)[=0° 28']. The calculated values of p for {1.0.10} and 

{T.0.12} are also added, and though my own measurements would 

agree better with these two forms, it is preferable, on account of the 

poor quality of the reflections, to assign them to the known form 

>{T.0.11}.

Measurements o/j-{1.0.11}.

Crystal 

No.

6

9

35

Reflection.

.....do........

.....do........

Size of face.

.....do........

.....do........

P (calculated 4° 59').

3 51

5 23

3 46

As measured by Groth and Arzruni, ^=4° 59}'. 

P calculated for {1.0.10}=5° 32'. 

p calculated for {1.0.12>=4 e 32'.

The form ^{1.0.11} is illustrated.in figures 23 and 24 (p. 66).

p {214} was first described by Moses on a crystal from Boulder 

County, Colo. It was also noticed by me as narrow faces on crystals 

19, 29, and 30 (see figs. 19 and 29, pp. 64, 67), tying in the zone c(001): 

Z(210). The faces gave poor reflections. The angles measured by 

Moses are also shown in the table below.

The form was measured on crystal 19 with the following result:

Measurements of p{2l4}.

Angle.

*.......

Calculated.

67 53 

29 55

Measured.

Schaller.

0 /

69 42 

31 22

Moses.

68 46 

30 17

In addition to the measurements of p{214} given above, the form 

was identified on crystals 29 and 30. These crystals, however, were 

so incompletely developed that they could not be well placed in 

polar position. The angle between p(214) and Z(210) was therefore 

measured, with the following results:

Measurements of angle p(2l4): 1(210).

o /

Crystal 29...................................................... 58 39

Crystal 30......................................................60 05

Calculated....................................................60 05
DISCUSSION OF THE PRISM ZONE. 55

On all three of these crystals the form occurred in the zone c(001): 

1(210], and on crystal 19 it was also Determined to lie in the zone of 

and between 2(102) and J(112), so that its determination as (214) is 

verified by its zonal relations.

DISCUSSION OF THE PRISM ZONE.

The prism zone contains numerous forms of somewhat complex 

symbols and a discussion 1 of these forms is here given in order to 

show how closely the forms approach the normal series.

The entire prism zone from Z>(010) to a(100) shows, when plotted 

in gnomonic projection (see fig. 35, p. 70), a partition into three parts, 

the points of division being m(110) and <2(310). The three zone 

segments are then:

(1) 6(010), r(120), 5(7.11.0), m(110).

(2) m(110), Z(210), £(15.7.0), C(940), Jf(520), Q(830), d(310).

(3) d(310), 0(720), Jf(510), #(11.2.0), .7(610), i(710), n(810), a(100).

In the following discussion, these three segments are taken up in

turn: 

(1) Zone segment b......m.

< b r S m Form................................................^010 12Q 7 n o no

Symbol^.......................................... 0 I 1 1

v '7

r ................................................ 0 1 -j- «> 1 v 4

7 In place of r or (7.11.0), the simple form 2 or (230) should occur.

The form S(7. 11.0) was not observed by me but was described by 

Warren. The measured angle (7.11.0) : (7.11.0) is given as 74° 51', 

whereas the calculated angle (230) : (230) is 77° 50', a difference too 

great to allow of the form being referred to the symbol (230). Compare also the remarks on page 69 on the indices of this form.

(2) Zone segment m......d.

Form......... .......

Symbol =T- ---------

v-l...... ...........

V

% * - 

N..................

( m """"UlO

......... 1

......... 0

......... 0

I 

210

2

1

1 .

0

0

R 

15. 7. 0

15

7

8

7.

4 

3

1

3

1 1

3 2

C 

940

9

4

5 

4

5 

3

2

3

? 1

3

F 

520

5 

2

3 

2

3

2

3 ,

2 Z

Q

830

8 

3

5 

3

5

4

q

d 

310

3

2

CO

00

' For a description of the methods of the discussion, see Hillebrand, W. F., and Schaller, W. T., The 

mercury minerals from Terlingua, Tex.: U. S. Geol. Survey Bull. 405, p. 13,1909.
56 COLOEADO FEEBEBITE AND THE WOLFRAMITE SEBIES.

The forms fit well into the normal series notwithstanding their 

complex indices.

(5) Zone segment d......a.

( d G M N j L n a Korm...........................^K) 720 510 n. 2.0 610 710 810 100

....................'. 35 - 6 7 8 °°

i;-3............................ 0^2 5 3 4 5 oo

v-2............................ .0 \ 1 2 3 oo

N3 ............................. 0 \\\ l \ 2 ' oo

All the new prisms fit well into the normal series.

HABIT.

Five very distinct habits were observed on the crystals examined, 

habit meaning the relative development and size of. the different 

crystal faces and the consequent resultant shape of the crystal as 

a whole. Thus twin crystals are not considered as necessarily of 

different habit from a simple untwinned crystal. These five habits 

are as follows:

1. Long, narrow, wedge-shaped. This is the habit most frequently 

observed for the ferberite crystals studied. This is the habit of the 

penetration twins (figs. 17 and 18, p. 64) but not of the contact .twins. 

(See Pis. VII and VIII, A, pp. 18, 19, and fig. 3.).

2. Short, prismatic, somewhat flattened parallel to the orthopinacoid a{100}. Crystals of this habit are fairly abundant. (See 

Pis. IX, p. 20, and X, p. 21, and fig. 4.)

3. Tabular, parallel to a{100}. Rarely observed in simple crystals 

but the common habit for the individuals of a contact twin. (See 

fig. 5, also the twin crystals shown in figs. 14 and 15, p. 63.)

4. Cubic, rare. (See PI. VIII, B, p. 19, and fig. G.)

5. Rhombic, fairly abundant. (See Pis. XI, p. 22, and XII, p. 23, 

and fig. 7.)

Besides the habits mentioned above, two forms were noted which 

owe their shape to the cleavage of the crystals and are therefore not 

habits of the mineral. The first of these forms occurs in thin plates, 

which, as can be seen by reference to figure 8, A (p. 58), owe their 

tabular appearance to the 6{010} cleavage. The complete crystal 

from which this thin plate was cleaved was probably of the fourth or 

cubic habit. The second form occurs in long, slender rods and likewise owes its peculiarity of form to cleavage. As illustrated in figure 

8, B, it is probably derived from the edge of a crystal of habit 1 (see 

figs. 3 and 9), where the prism Z{210} extended to the edge of the 

crystal.
HABIT. 57

Habit 1. The wedge-shaped crystals are generally striated in the 

prism zone with the forms a{100}, Z{210}, and ?ft{110} grading into 

one another, as shown in figure 9. On many crystals, however, the 

individual prism faces are sharply separated and commonly yield single

FIGURE 3. Long, harrow, wedge-shaped crystal of habit 1, the most frequently observed habit. Forms:

c{001}, n{100}, 7n{110},

b 

TIGUKE 4. Short, prismatic, somewhat flattened 

crystal of habit 2. Fairly abundant. Forms: 

c{001>, 6{010}, n{100>,

FIGURE 5. Tabular crystal of-habit 3. Common 

habit for contact twins, but rare for single crystals. Forms: c{001>, 6{010}, n{100}, 7n{110},

FIGUKEC. Cubic crystal of habit 4. Rare. Forms: FIGURE 7. Rhombic crystal of habit 5. Fairly 

c{001>, 6{010>, o{100>, <{102>. abundant. Forms: b{010}, a{100}, /{102}. 

distinct reflections. Figure 10 (crystal 4) also represents a typical 

crystal of this habit. On removing these crystals from the matrix, 

to which they are firmly attached, they usually cleave, and the resulting loosened crystal piece will consequently be much shorter in the
58 COLORADO FERBERITE AHI> THE WOLFRAMITE SERIES.

direction of the & axis than the original crystal. From the sharp edge 

on one side such cleaved pieces show a peculiar axlike shape.- (See 

fig. 11, crystal 2.) The penetration twins (figs. 17,18, p. 64, and PI. VIII, 

A, p. 19) are generally of this habit, and the contact twins (figs. 14 

and 15, p. 63) are of the tabular or third habit. The wedge-shaped 

crystals of this first habit are generally poor in forms, few being 

found except the common ones, a{100}, c{001}, Z{210}, m{110},

Habit 2. The short prismatic habit, somewhat flattened parallel to 

a{100}, is the common habit for the wolframite group in general and 

is fairly abundant on the Colorado ferberite. An example was shown 

in figure 4 (crystal 1), and figure 12 illustrates the same combination 

as shown in figure 4, but with a habit intermediate between the first

or wedge shaped and the second or 

short prismatic. The two habits show 

all gradations, and it is impossible to 

refer some crystals to one of these two 

habits rather than to the other. Figure 12 does not illustrate any particular crystal measured, but many were 

seen having about the relative proportions shown in the figure.

Habit 3. The tabular habit may be 

considered as a further development 

of the change from habit 1 to habit 

2, which is intermediate between 

habits 1 and 3. Single crystals of 

this habit, as shown in figure 5, are 

rare, but in contact twins they are 

a fairly abundant. The orthopinaFIGUKE 8.-Cleavage pieces of crystals. A, Coid, a{100}, is strongly Striated In 

thin tabular; £, long, prismatic. Forms: fi f prvs,tola of fV,ja hahit whprpfls c{ooi>, &{oio> cleavage, a{ioo}, z<2io>. tne twm crJstals °\ tnis naoit, wnereas

the other forms in the prism zone 

are in general nearly free of striae.

Habit 4. The cubic crystals were found abundantly on one specimen, 

aside of which was literally covered with them (PI. VIII, B, p. 19, and 

fig. 6). They were small, f ewbeingover amillimeter in length, and were 

highly iridescent. Some of the crystals are slightly elongated in the vertical direction, whereas others are nearly perfectly cubic. The shape of 

the crystals is conditioned by the combination being essentially that 

of the three pinacoids, a {WO}, &{010}, c{001}, two of which are at 

right angles to each other, and the third very nearly so, the angle 

being 89° 32'. The domej{102} is always present, and the pyramid 

A { 112} is usually developed. The crystals of this habit are very poor 

in forms.
HABIT.

FIQURK 9. Striationa on wedge-shaped crystals of habit 1, causing a rounded appearance in the prism 

zone/ The top base is also slightly striated and in some crystals rounded.

10. Crystel 4, wedge-shaped habit, which has sharp, distinct faces, not rounded as in figure 9. 

Forms: c{001>, 6{010}, a{m}, m{110}, Z{210},/{011}.

FIOTJRE 11. Peculiar shape of crystals of wedge-shaped habit caused by cleavage on b{010}-. Crystal No. 2. 

Forms: c{Wl}, 6<010}, w{n°>i 2{210},/{011>.

FIQUKE 12. Crystal of a short prismatic, somewhat FIGURE 13. Crystal of rhombic habit, nearly equiflattened habit. Forms: c{001}, fr{ 01°V, o<100}, dimensional. Compare with figure 7, p. 57.

m<110}, l{2lQ},f{on }. Crystal No. 24. Forms: b{010>, o<100>, «{102}.
COLOBADO FEBBEBITE AND THE WOLFRAMITE SEMES.

Habit 5. The rhombic crystals are very abundant on some specimens 

and other habits are then entirely absent. (See Pis. XI and XII.) 

The rhomboids consist of either a single crystal bounded by plane surfaces or of an agglomeration of innumerable crystals, each deviating a 

little more from strict parallelism with the first unit. The crystals are 

generally elongated parallel to the c axis, as shown in figure 7, though 

some of them are more nearly equidimensional, as shown in figure 13 

(crystal No. 24). The characteristic combination is &{010}, a{100}, 

i{102}, and other forms are rare. Many of these rhombic crystals are 

fairly large, the longer diameter of 2(102} in average individuals measuring nearly half a centimeter.

COMBINATIONS.

The combinations observed on the 38 crystals measured are shown 

in the following tables, wherein the different crystals have been 

grouped according to their habit, as the various habits have a markedly different combination. Thus the essential forms, that is, those 

which are characteristic for a certain habit, are given below for the five 

different habits observed. The forms are further grouped as prominent or not prominent, depending on whether or not they have a 

decided influence on the shape of the crystal. Forms that are not 

prominent are placed in parentheses.

Characteristic forms for each crystal habit.

F

c{001

6{010

o<1.00

7n{110

Z{210

/{OH

M102

#{904

^{112

w\lll

orm. l. Wedgeshaped.

/j

(6)

1

f

(<0

M

2. Short prismatic.

b

 <n»)

(/)

(0

(4)

M

3. Tabular:

(i)

(m)

(0

4. Cubic.

b

(0

00

5i Rhombic.

b

(D '

t

(#)

Combinations on crystals with wedge-shaped habit.

Form.

c{001}.. .........

6{010>... ........

o<100V...........

m{110}...........

Z<210>...........

J« 15.7.0V. .......

«940>. ..........

M{810>...........

/ {Oil}.. .........

-W904}. ..........

rU.0.11}.........

orf 111}.... .......

jam.. ......... o}ln>.... .......

Crystal No.

2

c 

6

a 

in 

1

f

 1

c 

6 

a 

m 

1

f

s

c 

b 

a 

m 

1

f

29

c 

6 

a 

m 

1

.P

30

c 

b

a 

m 

1

P

31

c 

6 

a 

m 

1 

R

C

H

01

32

.c 

6. 

a 

m 

1

f

<a

A

33

c 

b 

a 

m 

1

f

at

A

0

34

c 

b

' a 

m 

1

{,

ta

0

35

c 

6 

a 

m 

1

/

r 

u

0
COMBi-NATlONS. 01

Combinations on crystals with .short prismatic habit.

Form.

c(001 

WOIO 

ahoo

771(110

Z(210 

r{120 

R{15. 

(7(940 

JFY520 

0(830 

(5(310 

0(720 

Jf(510 

1" 11. 

610 

710 

810 

Oil 

104 

102 

904 

I.O. 

123 

5.9. 

Ill 

112 

337 

214 

313 

121 

112 

111

........

Ql

>.. .........

!>..,......

K. .........

14>.........

K. .........

........... 

K- .........

Crystal No.

1

c 

b 

a 

m 

I

r.

F

M

f

3

c 

6 

a 

m 

I

f

5

c

b 

a 

m 

I

T,

....I....

i

I

I

1

6

c 

b 

a 

m 

I

f

ia

0

7

c 

b 

a 

m 

I

f

0

9

c 

b 

a 

m 

I

d

j

f

t

ia

0

13

C

b 

a 

m 

I

M

n 

f

t 

H

B

ta

A

14

c 

6 

a

TO

I

a

M

N

r,

n

t 

H

d

15

c 

b 

a 

m 

I

f

t 

H

ta

A

16

c 

b 

a 

m 

I

t 

H

ta

17

c 

b 

a 

m 

I

TV

t

'

18

c 

b 

a 

m 

I

R

r.

Q

t

19

c 

b 

a 

m 

I

f

t 

H

B

E

a>

D

fa

20

c 

b 

a

TO

I

f

t 

H

E

ta

A

21

c 

b 

a 

m 

I

f

t

E

A

22

c 

b

a 

m 

I

F

f

t

ta

Combinations on crystals with tabular habit.

Form.'

c(001 

WOIO 

ahoo 

mhlO 

M210 

^{15.7 

Q{830 

n{810 

/{Oil 

W102 

Him 

£{5.9.

[...........

k..........

^ . ........

.6>. .......

4>........

Crystal No.

10

c 

b 

a 

m 

I

f

11

c 

6 

a 

m 

I

12

c 

b 

a 

in 

I

f

23

c 

b 

a 

m 

I 

R

Q

n

t

27

c 

b 

a

t 

H 

E

28

c 

b 

a

t 

H

Combinations on crystals with cubic and rhombic habits.

Form.

c{001 

WOIO 

ahoo 

K210 

«102 

J5T/904 

J{112

Cubic habit.

Crystal No.

36

c 

b

a

t

J

37

c 

b

a

' t

J

38

c 

b 

a 

I 

t

j

Rhombic habit.

Crystal No.

24

b 

a 

I 

t 

H

25

b 

a 

I 

t 

H

26

c 

b 

a

'"i" 

H
62 COLORADO FERBERITE AND THE WOLFRAMITE SERIES.

TWINNING.

Twin crystals were often observed. Only one twinning law was 

noticed, namely, with {023} as the twinning plane. The many 

groupings parallel to a{100} were carefully examined for evidences 

of twinning on the a(100) face, but none were seen. As these parallel 

groupings generally have the 2(102) face well developed, twinning on 

the a(100) face would cause a twinned face of 2(102) to assume the 

position of (T02), and there would then be an apparent rear orthodome 

as well as a front one on such a twinned crystal. The absence of such 

a rear orthodome would indicate that these parallel groupings were 

not twinned.

Though only one twinning law was observed, namely {023}, there 

were two kinds of twins according to this law, namely, contact and 

penetration twins. Both were observed many times, tho'ugh the 

contact twins are more abundant.

The contact twins" are illustrated in figures 14 and 15, which show 

the twinned crystal facing in two directions, or in other words show 

the two positions a twinned group will take according to which face 

of {023} acts as twinning plane. Both positidns of the twinned group 

have the same crystallographic relationship. The position shown in 

figure 14 shows the clinopinacoid &{010} of the twinned crystal adjoining the same form of the untwinned crystal. In figure 15 the basal 

.pinacoid c{001} of the twinned crystal is shown. In the two illustrations the relationships of the contact twins are more clearly indicated 

than can be done by a written description.

The line of contact of the two crystals affords some points of interest, 

but for the present only a description of it is given. Theoretically 

it should be a straight line, as drawn in figures 14 and 15, but actually 

it is very uneven, the two parts of the twinned crystal being very 

irregularly dovetailed, as illustrated diagrammatically in figure 16, 

which was drawn from a twinned crystal (notebook No. A13), as seen 

on the goniometer.

In the penetration twins tne containing unit is always much larger 

than the one which is partly embedded and projects out of the middle 

of the larger crystal, as shown in figure 17. The two crystals, though 

of different appearance, have the same combination of crystal forms 

as those shown in figures 14 and 15. Similarly figure 18 shows the 

same kind of penetration twin with the smaller twinned crystal in the 

opposite direction to that in figure 17. The large untwinned crystal 

in figure 18 is shown with one end cleaved off, due to the clinopinacoidal cleavage &(010). (See PL VIII, A, p. 19.)

The angle c(001): £(010) (fig. 17) is 29° 58', and the angle c(001): 

c (001) (fig. 18) is 60° 02'. These angular values are here given as 

reference will be made to them later and the position of the faces 

forming the angles can here well be seen.
TWINNING. 63

A peculiarity noted by Mr. Hess on several crystals similar to the one 

shown in figure 18 is that in front of the twinned crystal, on the larger 

untwinned unit, is a small cavity bounded by rough planes which

FIGURE 14. Contact twin on (02~3). Forms: 6{010}» 

a{100},m{110},Z{210}.

FIGURE 15. Contact twin on (023). Forms: 

c{001>, 6{010>, o{100>, m{110}, Z{210}.

FIGURE 16. Line of contact of two contact twins.

however suggest that they may be slightly developed terminal faces, 

such as/{Oil}. (See PL VIII, A, p. 19, center.) They may be 

caused, however, by crystals of scheelite, now removed.
04 COLORADO FEBBEK1TE AND THE WOLFKAMITE SEHIES.

FIGURE 17. Penetration twin on (02~3). Forms: c{001>, &{010>, a{100>, m{110}, 1{2W}.

FIGURE 18. Penetration twin on (023). Forms: c{001}, 6{010}, a{100>, m{110>, l{210}.

m

Vj

FIGURE 19. Crystal 29, showing rare form p. FIGURE 20. Crystal 32. Forms: c<001}, Z>{010}, 

Forms: c{001}, 6{010>,a{100>,«{210>, p{214>. o{100}, m{110>, 1{2W}, A011}, J{U2}.

FIGURE 21. Crystal 33. Wedge-shaped crystal with unequal development of the faces of /. Forms: 

c{001}, ft{010}, a{100>,
COLOEADO FERBERITE AND THE WOLFRAMITE SERIES. 66 

DESCRIPTION OF MEASURED CRYSTALS.

Only such crystals as are illustrated by drawings will "be here 

mentioned. The general types of habit have already been shown 

under the section entitled "Habit," where drawings of a few of the 

measured crystals were also introduced. In general the following 

figures show the crystals in their ideal development. As most of 

them were bounded on one side by the cleavage face (OlO) the exact 

dimension of the crystals in this direction could only be estimated, 

but by observing similar crystals that were intact it is believed that 

the proportions shown in the figures closely approximate the true 

relative dimensions. The crystals illustrated will bo grouped under 

the five habits.

Crystal 29 (fig. 19) is simple in its combination but shows the 

rare form p{214} fairly well developed. It is, moreover, except 

c{001}, the only terminal form on this crystal. Crystal No. 32 (fig. 

20) shows a common combination for a number of minute stout 

crystals in which the wedge shape is not so characteristic as in crystal 

No. 33 (fig. 21). Here also the upper and lower faces of/{Oil} are 

unequally developed. With the large development of Z{210} the 

pyramid faces generally become smaller.

Crystal 5 (fig. 22) is remarkable in possessing such a small orthopinacoid, a{100}, the large faces of ^{810} seeming to replace 

the usually large faces of a. Crystals 6 (fig. 23) and 9 (fig. 24) are 

both shown in their actual condition, with one side bounded by 

the cleavage face (OlO). Both of them show a line face of the rare 

negative dome p{ 1.0.11} and figure 24 also shows the large positive 

dome £{102}. The rare prism ^{310} is shown as a line face, and 

a face of ?{610}, though not shown, is also present. Crystal 13 

(fig. 25) shows a number of new and rare forms, all as narrow faces, 

generally mere line faces, except one form which is present as a 

minute equidimensional face. The new forms #{904}, .A {337}, 

B{123}/and the rare forms n{8lQ} and it{104} are the ones referred 

to. The clinodome, /{Oil}, is much narrower and longer than 

is usual for the faces of this form. Crystal 16 (fig. 26) gives a 

combination seen on numerous crystals not measured. The new 

form .Z7{904} is generally present on such crystals. Crystal 17 

(fig. 27) shows ?{610}, n{810}, and o{Tll} besides the more common 

forms. Crystal 18 (fig. 28) shows the striations observed on A{112,}, 

these striae being parallel to the intersection edges (112) : (001) 

and (112) : (210), respectively. The crystal is also more elongated 

in a vertical direction than is usual. Crystal 19 (fig. 29) shows 

a number of new pyramids, namely, Z>{313}, 5{123}, #{5.9.14}, 

and the rare pyramid £>{214}. The zonal relationships of J(112), 

5(5.9.14), 5(123), /(Oil), and m'(IlO) could be weU seen on this 

crystal. Crystal 20 (fig. 30) also shows the new form £"{5.9.14}, as 

weU as A {337} and #{904}. 

^35659° Bull. 583 14 5
66 COLORADO.FERBERITE AND THE WOLFRAMITE SERIES.

m*

FIGURE 22. Crystal 5, remarkable for its small FIGURE 23. Crystal 6, with rare form r. Forms: 

orthopinacoid o{100}. Forms: c{100}, 6{010}, c{001>, 6{010}, c{100>, m{110>, Z{210>, /{Oil},

24. Crystal 9, with raro forms r and d. Forms: c{001>, 6{010}, o{100>, m{110>, ^{210}, d{310>, 

/{Oil}, t{102}, r{1.0.11}. The form j{610), not shown in the figure, is also present on this crystal.

FIOUEE 25. Crystal 13, showing the new forms A,B, and H and the raro forms n and «. Forms: c{ 001}, 

6{010}, o<100>, m{110>, ^210}, 7i<810},/{011>, «{104}, t<102>, #{904>, ^{337},
MEASURED CRYSTALS. 67

Crystal 36 (fig. 31) shows a cubic crystal somewhat elongated 

in the vertical direction. The form £{102} is invariably present on 

these crystals, as is also generally //{112}. Figure 32 illustrates a

H

FIGURE 26. Crystal 16, a combination observed on FIGURE 27. Crystal 17, showing raro forms

many crystals not measured. Forms: c{001},6<010}, n, j, and o. Forms: c{001>, b{QW}, a{ioo>,

a{100}, m{110}, /{210>, <{102}, H{904}, ^112}, ^{111}. m{110}, 1{2W}, /{610}, n{810}, t{W2},

H

FIGURE 28. Crystal 18, showing 'Striations on A. Forms: 

c{001>, 6{010}, o{100}, m{HO}, 

/{210},*{102},/f{U2}.

FIGURE 29. Crystal 19, showing new forms D, B, and E, 

The zone ^{112}, £{5.9.14}, JS{123>, /{Oil}, and 7n'{110} is well 

shown. Other forms are c{001}, 6{010}( o{100}, TTI{IIO}, f<210}, 

'^{102}, J?{904}, w{lll>, p{214}, J>{313}.

cubic crystal apparently slightly elongated in the direction of the 

a axis, but in reality the original crystal was elongated parallel to 

the & axis, as the crystal shown in the drawing is incomplete, part of
68 COLORADO FERBERITE AND THE WOLFRAMITE SERIES.

FIQUEE 30. Crystal 20, with new forms H, A, and E. Forms: c{001}, 6{010}, o{100}, m{110}, l{210}, 

/{Oil}, £{102}, H{904}, ^{337},4{112},^111}, £{5.9.14}.

FIGURE 31. Crystal 36, a cubic crystal, somej what elongated parallel to its vertical axis. 

1 Forms: c{001}, &{010}, a{100}, i{102},4{112}..

FIGURE 32. Cubic crystal (No. 37), apparently 

elongated parallel to o axis, but in reality

elongated parallel to & axis, tho left-hand 

side of the crystal having cleaved off.

3. Rhombic crystal (No.- 25),with the 

broad orthopinacoid replaced by numerous narrow alternating faces of a{ 100} and l{ 210}.

H

FiQTjitE34. Crystal26,arhomblccrystal. Forms: 

c{001}, 6{010}, o{100},
FORM SYSTEM OF THE WOLFRAMITE GROUP. 69

it having cleaved off. The face of t{ 102} is much narrower than that 

on figure 31.

Crystal 25 (fig. 33) shows a rhombic crystal similar to those shown 

in figures 7 and 13 (pp. 57, 59), with the broad orthopinacoid a{100}, 

replaced by numerous narrow alternating faces of a{100} and Z{210}, 

those of Z{210} being much narrower than those of a{100}. The 

form #{904} is also present. The drawing is, however, but a poor 

representation of the true appearance of the crystal. Crystal No. 26 

(fig. 34) shows the rhombic combination, a, b, t, modified by c{001}

FORM SYSTEM OF THE WOLFRAMITE GROUP. 

CRITICAL STUDY OF FORMS.

Before the monoclinic character of wolframite was determined it 

was concidered as orthorhombic, and it is therefore not possible to 

tell which are the negative and which are the positive forms in the 

earlier descriptions. The list of forms is fairly extensive, a total of 

49 being recorded. Some of these forms will be briefly commented 

on, as follows:

${7.11.0} was described by Warren as new and the letter i assigned 

to it. As, however, i had already been preempted by the form 

{303}, the letter 8 is- assigned to the form {7.11.0}. The measured 

angle is given as follows: (7.11.0): (7.11.0) = 74° 51'. The calculated value is 75° 16' and the calculated value for the simpler form 

{580} is 74° 16'. The differences between the angles measured and 

the values calculated are, for {7.11.0} 0° 25' and for {580} 0° 35'. 

Although the difference is slightly less for the more complex symbol, 

the agreement is far from satisfactory. The correct symbol of the 

form is therefore in doubt, and, though the indices would seem to 

be possibly simpler than {7.11.0}, these indices are inserted in the 

table of forms, but are marked with a (?) to indicate that the symbols need verification. (See also p. 55.)

10 {021} was noted only by Descloizeaux and by Jeremejew. 

Attention is called to the fact that {021} occupies almost exactly 

the same position as c{001} in twin position. It is therefore possible 

that a face of c{001} in twin position (as shown in fig. 35) was 

measured and taken for (021).

c(001) : w(021)=60° 01' (calculated). 

c(001) : c(001)=60° 02' (calculated; p. 62

The difference between the two values is so small as to be unmeasurable. It seems right, therefore, to regard the form i0{021,} as doubtful and as at least needing verification before it can be accepted as 

a definite form.
70 COLORADO FERBERITE AND THE WOLFRAMITE SERIES.

gr{095}, found only by Descloizeaux, also needs verification. The 

measured angle agrees much better with the slightly more complex 

form {0.11.6}.

(Oil) : (095) =16° 47' (measured by Descloizeaux). 

(Oil) : (095) =16° 26' (calculated); difference =+21'. 

(Oil) : (0.11.6)=16° 54' (calculated); difference =-07'.

The form is therefore considered doubtful, on account of the uncertainty of its symbol and because it needs verification.

FIGURE 35. Gnomonic projection of forms of the wolframite group. Several forms are plotted in twin 

position (open circle) to show their close position to untwinned forms. Thus note particularly c and w, 

s and t, j£ and a, t and s, s and s, d and V.

' £{304}, described only by Groth and Arzruni, is also doubtful, as 

the measured angles vary considerably from the values calculated 

for them.

Angles for the form d { 304}.

Anglo.

(001) :(304)........

(102) : (304).. ....

(504) :(101)........

Measured.

39 56

11 51

9 17

Calculated.

38 23

10 30

8 15

Difference.

+1 33

+ 1 15 .

+ 1 02
FORM SYSTEM OF THE WOLFRAMITE GROUP. 71

, described first by Groth and Arzruni and later noted by 

Groth (but without measurement), is also doubtful. (001) : (T01) = 

48° 37' measured and 46° 38' calculated, the difference being 1° 59'.

0(113} given by Miller * has always been considered a questionable 

form. Though inserted by Goldschmidt in his Winkeltabellen with 

a query, it had best be omitted. The symbol0 may be a misprint 

for {112}.

Eakle gives the letter v to a new form {T22} on wolframite from 

Nevada, but as the letter v is already preempted by the form {552}, 

Eakle's letter is changed to V. Eakle's letter h should be changed 

to d and d changed to e.

It may be noted, too, that the correctness of the positive or negative character of several of the forms listed is very questionable. 

This is particularly true of the domes described by Krenner, who 

himself called attention to this uncertainty.

Figure 35 shows the gnomonic projection of all the known forms of 

the wolframite series except r{321}, which falls outside of the projection, and #{754}, which was described after the gnomonic projection 

Was drawn and reproduced. The position of the forms is indicated 

in figure 35 by dots, whereas the position of some of the forms in twin 

position (twinned on {023}) is shown by open circles.

All the forms lie in well-developed zones. The prism zone is the 

richest, containing a total of 17 forms, but hardly any of the simple 

zones are poor in forms.

The position of many of the twinned forms is nearly identical with 

other, forms which are not twinned and which are in their normal 

position, as, for example, y{lQ2} and a{121}, c{001} and w{Q2l], 

2{102}_and s{12l} } s{l21}~and *{102}, a{l2l} and y{102}, ${T21} 

ands{121}. .

FORMS AND COORDINATE ANGLES.

The following table of forms and coordinate angles 'shows several 

points to which attention may be called. If a form is considered 

doubtful that is, if it seems uncertain whether such a form actually 

exists the question mark used to indicate this is placed with and 

immediately following the letter of the form. Thus w ?{021} means 

that there is doubt as to whether such a form has actually been found. 

If, on the other hand, there is no question about the existence of the 

form, but the symbols seem to be incorrectly determined, or at least 

a verification of the correctness of the measurement is desired, the 

question mark is placed after the symbols, thus ${7.11.0} ?.

References are given when the form has been seen and described 

by only one observer or two independent observers. If at least three 

different observers have noted the form its confirmation would seem

i Miller, W. H., Elementary introduction to mineralogy, p. 473,1852.
72 COLORADO FERBERITE AND THE WOLFRAMITE SERIES.

to be so well established that references to it are in general not necessary. The occurrence of the form on the three members of the 

wolframite group has also been noted.

Forms and-coordinate angles, wolframite grouj).

- [0=0.8255; c=O.S664; 0=89° 32'.]

No.

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

26 

27 

28 

29 

30

31 

32 

33 

34 

35

36 

37 

38 

39 

40

41

.42 43' 

44

45

46 

47 

48 

49

Letter.

c 

6 

a 

r 

S

m 

I 

R 

C 

F

1

G

M

N

i

n 

wf of

f 

r

' u

9

.y

t

9f 

A? 

h 

i

. H 

k

V 

s

(T

B

E 

D 

e

0 

V 

ta 

A 

A

X

r

e 

P

Symbol.

Goldschmidt.

0 

Ooo 

oo 0 

oo 2 

co-y.

CO

2oo

J/- oo

$00 

$00

$co 

3 co 

|co 

5co

Jj^OO

6co 

7oo 

800 

02 

Of

01 

-T<rO

+io .

+f 0 

-JO

+£0 

-JO 

-10 

+10 -*o

+1

=1 

-il 

-12

+ 12

+H

+T\A +-V

-i

+1 

+* 

+*

+H

+32 

-21 

+H

Miller.

001 

010 

100 

120 

7.11.0?

110 

210 

15.7.0 

940 

520

830 

310 

720 

510 

11.2.0

610 

710 

810 

021 

095

Oil 

1.0.11

104 

103 

102

102 

304 

101 

101 

403

904 

502 

132 

122 

121

121 

123 

5.9.14 

313 

112

111 

552 

111 

112 

337

754 

321 

211 

214

*

90 00 

000 

9000 

31 12 

37 38

50 27 

6734 

6858 

69 51 

71 44

72 48 

74 37 

76 44 

80 38 

81 28

82 10 

83 16 

8406 

0 16 

0 18

0 32 

9000 

9000 

9000 

90 00

9000 

9000 

9000 

9000 

9000

90 00 

9000 

21 41 

30 48 

31 00

31 24 

31 47 

34 31 

47 21 

50 01

50 14 

50 22 

50 40 

50 53 

50 58

59 35 

61 14 

67 29 

67 53

P

0 28 

9000 

9000 

9000 

9000

9000 

90 00 

9000 

90 00 

90 00

90 00 

90 00 

90 00 

9000 

90 00

90 00- 

9000 

9000 

6000 

57 20

40 54 

4 59 

15 08 

19 41 

27 19

28 03 

37 55 

46 10 

4636 

54 17

67 07 

69 04 

54 26 

45 15 

63 41

63 46 

34 12 

34 03 

74 44 

33 59

53 34 

73 35 

53 49 

34 29 

30 31

64 57 

74 29 

66 10 

29 55

References.o

. 12 

13 

4,13 

2,3 

2

4,13 

3,13 

3

4 

4,6 

5,6 

5

13 

5 

5

18

13 

13 

13

5

13

7

11,13

Ferberite, 

FeWO<.

c 

6 

a

T

S

m 

I 

R 

C 

P

i

c

M

N

.;

71

 /

r 

u

!/ 

t

n

s

B 

E 

D

e

0

(a 

4 

A

P

Wolframite, 

(Fe.Mn) 

W04 .

c 

b 

a 

r

m -I

d

n

g

f 

r 

u 

g 

y

t 

s A ft 

i

k

V 

s

e

0 

V 

(a

,

Hiibnerite, 

MnWO«.

c 

b 

a

m 

I

i

f

t

ta 

J

X

r

Numbers refer to the Bibliography, pp. 74-75.
COLOEADO FERBERITE AND THE WOLFRAMITE SERIES. 73

COMBINATIONS OBSERVED ON THE WOLFRAMITE GROUP.

The following table shows the combinations described on minerals 

of the wolframite group commencing with the definite establishment 

of the monoclinic character of the group by Descloizeaux in 1850. 

As wolframite was considered to be orthorhombic in the earlier 

descriptions, the combinations of those writers are not given, as the 

positive and negative forms can not be differentiated. Numbers 

after names 'of authors refer to similar numbers in the bibliography.

Combination No. 10 gives the entire list of forms mentioned by 

Descloizeaux and doubtless represents several crystals, in part probably the same as combinations Nos. 1, 2, >and 3. Combination 11 

likewise gives the complete list of forms observed by Jeremejew, as 

I was not able to decipher the individual combinations from the 

Russian text.

*

Combinations described on crystals of minerals of the wolframite group.

No.

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 

26 

27 

28 

29 

30 

31 

32 

33

34

35

36 

37 

38 

39

Combination.

.a m Ify t s o .....................

bak. ...........................

baik. ..........................

badik. ........................ 

cbd. ...........................

bat.. ........................... 

bay h.. ................. ........

bhv. ...........................

cb a dyik^e. ...................

b(a)m(lt A............ ......... 

a mlft.... ................ '..... 

a mfo ..........................

cbarmqdseoe V. .............

Mineral.

.....do............

.....do............

.....do............

.....do............

.....do............

.....do............ 

.....do............

.....do............

.....do............

.....do............

.....do............

.....do............

.....do............

.....do............ 

.....do............

.....do............ 

.....do............ 

.....do............ ....:do.. ..........

.....do............

.....do............ 

.....do............

.....do............

Wolframite....... 

.....do............

Hiibnerite........ 

.....do............

.....do............ 

Wolframite....... 

.....do............

.....do............

Wolframite....... 

.....Ao.a. ......... 

Hiibnerite........

Locality.

.....do............

.....do............

Altenberg.........

Zinnwald ......... 

.....do............ 

.....'do.. ..........

Schlaggenwald ....

Altai, Russia...... 

Schlaggenwald . . . .

Felsobanya.......

.....do............

.....do............ 

.....do............

.....do............ 

.....do............ 

.....do............

.....do............

.....do............

.....do............ 

Altenberg......... 

Zinnwald ......... 

Pyrenees'. ......... 

Spain ............. 

Fichtelgeblrge. .... 

Silverton, Colo.... 

New Mexico...... 

.....do............ 

Altai.............. 

Japan............. 

South Dakota 

(Colorado?). 

New South Wales. 

Boulder County, 

Colo.

Bolivia........... 

Nevada........... 

Peru..............

Author.

Descloizeaux (1). . 

.... .do. (l). .......

.....do.(l). .......

..... do. (1)- -------

.....do.

.....do. 

.....do. 

.....do.

.....do.

Jeremeje 

Groth £ run! (< 

Krenner 

.....do.

.....do. 

.....do.

.....do. 

.....do. 

.....do.

.....do.

.....do.

.....do. 

Groth (6 

.....do.( 

Bertranc 

Seligmai 

Sandber 

Penfleld 

.....do.( 

.....do.( 

Jeremeje 

Jimbo (1 Warren

Anderso 

Moses (1

Boggild 

Spencer 

Eakle (1 

Tronquo

1). .......

1)........ 

1)........ 

1). .......

2)........ 

2)

w(3)..... 

ind Arzk......

5)........

5)........ 

5)........

5)........ 

5)........ 

5 ........

5 ........

5 ........

5 ........

3)""I"!

1(7)...... 

l (8) ....... . 

ger(9).... 

(10)...... 

10}....... 

10).......

S??.::::

iq\

a(14)..... 

5).........

[16).......

17)....... 

8). .......

y(10)....

Date.

1850 

1850 

1850 

1850 

1850 

1850 

1850 

1850 

1870 

1870 

1872 

1873

1875 

1875 

1875 

1875 

1875 

1875 

1875 

1875 

1875 

1875 

1878 

1878 

1882 

1880 

1888 

1892 

1892 

1892 

1894 

1899 

1901

1904 

1905

1905 

1907 

1912 

1913

a Eaklo states that "All of the material contains iron and is to be classed as wolframite rather than as 

hubnerite." His next sentence," The crystals arc tabular parallel to the orthopinacoid and some of them 

are exceedingly thin and almost transparent, with a deep-red color," would indicate, however, that the 

material was more likely hiibnerite than wolframite.
74 COLORADO FEEBERITE AND THE WOLFRAMITE SERIES.

The following combinations were observed by the writer on the 

ferberite from Colorado described in this report:

cbamlfrtoeo cbamlf

cbamlfo cbaml

cbamldjftj-wo cbaml/.

cbamlMnfut HBtaAA cbamlRQnft

cbamlGMNLntHAso cbatHE

cbamlf tHud A. cbatH

cbamltHcaA cbatd

cbaml NnftAo cbat

cbamlR CQtA claltd

cbamlftHB EaJp.D baltH

cb.amlftHtaAA baltH

cbamlftEdA cbatH 

cbaml Ffttad

By calculating the percentage occurrence for the 77 combinations 

listed (the 39 given in the table and the 38 observed by. the writer), 

the forms of the wolframite group fall into three classes, as follows:

(1) Prominent forms:

Letter.................... a 'b m c I / t

Symbol.................. (100) (010) (110) (001) (210) (Oil) (102)

Per cent of occurrence.... 97 84 ,75 67 67 57 51

(2) Less prominent forms:

Letter.................... a> o A y H s o .

Symbol.................. (Ill) (111) (112) (102) (904) (121) (121)

Per cent of occurrence.... 35 24 21 21 17 12 11

(3) Rare forms: All the remaining forms, 35 in number.

BIBLIOGRAPHY.

1. Descloizeaux, A., M&moire sur les formes cristallines du wolfram: Annales chim. 

et phys., 3d ser., vol. 28, p. 163, 1850.

2. Descloizeaux, A., Nouvelles recherches cristallographiques et optiques sur la 

forme clinorhombique du wolfram: Annales chim. et phys., 4th ser., vol. 19, 

p. 168, 1870^

3. Jenemejew, P., Wolfram-Krystalle im Vergleich zu den Krystallen des Cplumbite: 

Russ.-k. mineral. Gesell. St. Petersburg Verh., 2d ser., vol. 7, p. 301,1872.

4. Groth, P., and Arzruni, A., Ueber die Krystallform und die optische Eigenschaften 

des Wolframs und dessen Beziehungen zum Columbit: Poggendorff's Annalen, 

5th eer., vol. 29, p. 235, 1873.

5. Krenner, J. A., Wolframit aus dem Trachyte von Felso-Banya: Min. pet. Mitt., 

vol. 5, p. 9, 1875.

6. Groth, P., Die Mineraliensammlung der Kaiser-Wilhelms-ITniversitat, Strassburg, 

p. 161, 1878. 

7. Bertrand, E., Sur la hiibneVite des Pyre'ne'es: Soc. min. de France Bull. 5, p. 90, 

1882. ' "

8. Seligmann, G.,Mineralogische Notizen, III; 12, Wolframit: Zeitschr. Kryst.Min., 

vol. 11, p. 347, 1886.

9. Sandberger, F., Ueber Lithionitgranite mit besonderer Riicksicht auf jene des 

Fichtelgebirges, Erzgebirges und des nordlichen Bohmens: K. bayer. Acad. 

Miinchen, Math.-phys. Classe, Sitzungsber., 1888, p. 423.

10. Penfield, S. L. (with Genth, F. A.), Mineral notes, No. 52: Am. Jour. Sci., 3d 

ser., vol. 43, p. 184, 1892.
BIBLIOGRAPHY. 75

11. Jeremejew, P., Ueber den Wolframit von der Demidow'schen Kupfergrube in 

der Nahe des Kolywan'schen Bergwerkes, Altai: Russ.-k. mineral. Gesell. 

Verb., vol. 31, p. 404,1894.

12. Jimbo, K., Notizen iiber die Mineralien von Japan: Tokyo Coll. Sci. Jour., vol. 

11, p. 213, 1899.

13. Warren, C. H., Mineralogical ~notes: Crystal of iron wolframite from South Dakota: 

Am. Jour. Sci., 4th eer., vol. 11, p. 372, 1901.

14. Anderson, C., Mineralogical notes No. I: Topaz, beryl, vesuvianite, tourmaline, 

and wolframite: Australian Mus. Records, vol. 5, p. 303, 1904.

15. Moses, A. J., The crystallization of luzonite and other crystallographic studies; 

Crystallized wolframite from Boulder County, Colo.: Am. Jour. Sci., 4th ser., 

vol. 20, p. 281, 1905.

16. Boggild, 0. B., Mineralogia Groenlandica: Meddelelser om. Greenland, No. 32, 

p. 179, 1905.

17. Spencer, L. J., Minerals from Bolivia: Mineralog. Mag., vol. 14, p. 334,1905.

18. Eakle, A. S., The minerals of Tonopah, Nev.: California Univ. Dept. Geology 

Bull., vol. 7, p. 18, 1912.

19. Tronquoy, R., Surla htibn&rite: Soc. franf. mine'ralogieBull. 36, p. 113,1913.

o