116 GEOLOGY AND GOLD DEPOSITS OF THE CRIPPLE CREEK DISTRICT. 
11 Kalgoorlite." —Supposed telluride of gold, silver, and mercury (HgAu 2 Ag 6 Te 6 ). 
Probably a mixture of petzite and coloradoite. a Iron black; not known from 
Cripple Creek. 
Melonite. —Nickel telluride (Ni 2 Te 3 ). Reddish white; granular or foliated; not 
known from Cripple Creek. 
Altaite. —Lead telluride (PbTe). Tin white, with yellowish tinge ; massive, with 
cubic cleavage; not known from Cripple Creek. 
Hessite. —Silver telluride (Ag 2 Te; Te 36.7, Ag 63.3). Sometimes with up to 13 
per cent gold. Isometric; lead gray or steel gray; not known from Cripple Creek. 
Petzite. —Telluride of silver and gold (Ag,Au),Te. Ag:Au = 3:l. Te 32.5, 
Ag 42, Au 25.5. Massive; steel gray to iron black; stated by T. A. Rickard to occur 
on the Geneva claim of the Gold King mine. 
Tetradymite. —Sulphotelluride of bismuth (Bi,(Te,S) 3 ). Steel gray; massive or 
small crystals. This is the most wide-spread tellurium mineral, but it is not known 
from Cripple Creek. 
Nagyagite. —A sulphotelluride of gold and lead, with varying composition. 
Gold 6 to 13 per cent. Tabular crystals; blackish or lead gray; not known from 
Cripple Creek. 
The tellurides which enter into the ores of Cripple Creek have the general formula 
(Ag,Au)Te 2 and comprise the three species calaverite, sylvanite, and krennerite. 
Sylvanite. —Telluride of gold and silver [(Au,Ag)Te,]. Au :Ag=l:l. Te 62.1, 
Ag 13.4, Au 24.5. Monoclinic; usually crystallized or in arborescent forms; twins 
frequent, specific gravity = 7.9 —8.3; excellent cleavage; color pure steel gray or 
silver white, inclining to yellow. The name of sylvanite is derived from the province 
of Transylvania, Hungary, where it was first found. The presence of this mineral in 
Cripple Creek was first suggested by Mr. R. Pearce 6 on the basis of an analysis of ore 
from the Moose mine; but the mineral was finely divided and some silver ore like 
tetrahedrite might easily have been present. Since then the presence of typical 
crystallized sylvanite has been shown by Dr. Charles Palaehe/ the occurrences being 
at the Mabel M. and Little May mines, and from another doubtful locality, the 
material being obtained from Mr. F. M. Woods, of Victor. The small crystals are 
thin-tabular parallel to b (010) and are bordered by planes of the orthodome zone. 
T. A. Rickard d states that the mineral has been found at the Independence, Port¬ 
land, Moon-Anchor, and Anchoria-Leland mines. During our investigation it was 
also identified from the Elkton and Blue Bird mines. 
Krennerite. —Telluride of gold and silver [(Au,Ag) Te,]. Composition variable. 
The original analysis of material from Xagyag, Transylvania, gave 19.44 per cent of 
silver. The analysis of Cripple Creek material gives Au 43.86, Ag 0.46, Te 55.68, or 
practically the same composition as calaverite. Orthorhombic; crystals normally 
developed; prismatic with striated prism combined with pinacoid and domes. 
Identified from the Independence mine/ 
“ Spencer, L. J., Mineralogical notes on Western Australian tellurides; the nonexistence of “kalgoorlite” and “coolgardite 
as mineral species: Min. Mag., vol. 13, 1901-1903, pp. 268-290. 
b Proc. Colorado Sci. Soc., vol. 5, 1894-1896, p. 15. 
cZeitschr. 1. Krystall. u. Min., vol. 34, 1901, p. 539. Also Am. Jour. Sci., 4th ser., vol. 10, 1900, pp. 419-422. 
d The Cripple Creek gold field: Inst. Min. and Met., London, vol. 8, 1899. 
f Myers, W. S., and Penfield, S. L., Am. Jour. Sci., 4th ser., vol. 5, 1898, p. 376. 
