70 
ECONOMIC GEOLOGY OF SILVERTON QUADRANGLE, [bull. 182. 
zunyite given by Hillebrand as the mean of eleven partial analyses 
is as follows: 
Analysis of zunyite. 
Constituent. 
Per cent. 
Constituent. 
Per cent. 
SiOo - 
24. 33 
.20 
57.88 
.10 
.24 
Trace. 
10.89 
P2O5 
.60 
Feo0 3 
F 
5.61 
Alo0 3 
CI 
2.91 
Less O .- 
KoO 
NaoO . 
102. 76 
3.02 
LioO... 
HoO 
99.74 
Although of much scientific interest, the mineral at present has no 
economic importance. 
Other minerals. — Sericite, epidote, chlorite, and zircon occur in 
some of the ores, often merely as microscopic constituents. In the 
mines of Silver Lake Basin, chlorite, with the usual green color and 
minute radially foliated structure, occurs as nests in the vein quartz. 
The spots of chlorite are commonly regarded as an indication of good 
ore. It is abundant also in ore from the Silver King tunnel, on Mill 
Creek, and in vein quartz carrying pyrite in the Barstow mine. Seri- 
cite is often associated with kaolinite in ores formed by partial replace- 
ment of rhyolite and related potash-bearing rocks. A little chalcedony 
was noted in the Camp Bird ore. Alunite, although occurring in 
the National Belle mine and as an alteration product of some of the 
volcanic rocks of the Red Mountain range, has not been noted as a 
true gangue mineral. Gypsum occurs occasionally as small crystals 
in vugs of the Red Mountain ores. 
In a fissure in the Silver Ledge mine there is a considerable quan- 
tity of a soft white material which, when moist, has a beautiful 
faint-green tint. When dry the substance is a snow-white powder, 
apparently of great purity. A partial analysis of this substance by 
Dr. Hillebrand gives the following approximate chemical composition : 
Constituent. 
Per cent. 
Constituent. 
Per cent. 
SiOo ... . . 
14.83 
39.42 
40. 25 
4.26 
.20 
A1 2 3 (with trace of Fe 2 3 ) 
CaO 
C0 2 (calculated for CaC0 3 ) 
0.68 
HoO . 
.53 
S0 3 
100. 17 
This may be calculated as a mixture of allophane, aluminite, gibbs- 
ite, alunite, and calcite, in the following proportions, by weight: 
Per cent* 
Allophane (hydrous silicate of alumina) ,... .__ „ 58.0 
Aluminite (hydrous sulphate of alumina) 15.5 
Gibbsite (hydrate of alumina) 16.2 
Alunite (hydrous sulphate of alumina and potash) 2.0 
Calcite 1.2 
92.9 
