MINERALOGY-THE TELLURIDES. 
117 
Calaverite .—Telluride of gold and silver [(Au,Ag) Te,]. This mineral, previ¬ 
ously known from Boulder County, Colo., and from Calaveras County, Cal., was first 
identified from Cripple Creek by F. C. Knight “ in 1894. About the same time it was 
found at three separate localities in the district by Doctor Hillebrand. 6 Elaborate 
studies of its crystallography were made in 1901 and 1902 by S. L. Penfield and 
W. E. Ford c in the United States and by G. F. Herbert Smith and G. T. Prior/ in 
England. 
Some of the calaverite from Cripple Creek differs from that of other localities in 
having an exceptionally small percentage of silver. Most of the following analyses 
were made of well-crystallized material. 
Analyses of calaverite from Cripple Creek. 
i. 
2. 
3. 
4. 
5.o 
6 .b 
7. 
8. 
Te. 
56.22 
57.60 
57.40 
57.30 
(57. 25) 
40.99 
(56. 75) 
42. 77 
57.87 
56.93 
Au. 
40.14 
39.17 
40.. 83 
41.80 
41.66 
41.90 
Ag. 
3.63 
3.23 
1.77 
.90 
1.74 
.40 
.77 
.79 
99.99 
100 
100 
100 
99.98 
99.92 
100.30 
99.62 
a Plus gangue 0.02 per cent; tellurium by difference. b Plus gangue 0.08 per cent; tellurium by difference. 
1. F. C. Knight, Cripple Creek. 
2. W. F. Hillebrand, Prince Albert mine.) 
3. W. F. Hillebrand, Raven mine. >Specific gravity, 9.0, impurities subtracted. 
4. W. F. Hillebrand, C. O. D. mine. 
5. Penfield and Ford, Monument mine. Specific gravity, 9.328. 
6. Penfield and Ford, Cripple Creek. Specific gravity, 9.388. 
7. Smith and Prior, Raven Hill. Specific gravity, 9.155. 
8. Smith and Prior, Cripple Creek. Monoclinic. 
The calaverite occurs commonly in slender, deeply striated prisms, elongated 
in axis of symmetry. Ordinarily they are very small, but sometimes reach 1.5 
cm. in length. The faces have very high indices and do not fall in zones. On the 
whole the development is extremely unusual and presents some features difficult to 
explain. The axial ratio and angles resemble those of sylvanite. Smith and Prior d 
attempt to account for this puzzling crystallographical development by assuming 
triclinic symmetry accompanied by complicated twinning—of which, however, 
there is little external evidence—and believe that the crystals consist of an “inter¬ 
mingling of different structures, indicating that the crystals are really not homo¬ 
geneous. ” Massive calaverite occurs more rarely, but was noted from the Blue 
Bird mine; it has here a more bronzy-yellow color. There is no cleavage, a notable 
distinction from sylvanite. Brittle; hardness, 2.5; color, silver white, with a yel¬ 
lowish tinge. The calaverite from the original localities, as well as that from Kal- 
goorlie, Western Australia, has a pale, bronze-yellow color, usually absent in the 
Cripple Creek mineral, which in small particles is rather difficult to distinguish 
from pyrite. Calaverite occurs massive only in certain granitic and phonolitic 
a Proe. Colorado Sci. Soc., vol. 5, 1894-1896, pp. 66-71. 
* Geology and mining industries of Cripple Creek district: Sixteenth Ann. Rept. U. S. Geol. Survey, pt. 2,1895, pp. 133-135. 
« Am. Jour. Sci., 4th ser., vol. 12, 1901, pp. 225-246. 
d Min. Mag., vol. 13, 1902, pp. 122-150. 
