176 ANALYSES OF ROCKS, U. S. GEOLOGICAL SURVEY. [no. 228. 
6. TENMILE DISTRICT. 
Rocks described by Cross in 14th Ann., p. 165. Analyses made in 
the Denver laboratory — A and C by W. F. Hillebrand, B l)y L. G. 
Eakins. 
A. Quartz-hornblende-mica-porplryrite, Gold Hill. Yellowstonose. 
Contains plagioclase, hornblende, biotite, and quartz in a groundmass 
of quartz, orthoclase, and a little plagioclase. P. R. C. 510. 
B. Quartz-porphyrite, Sugar Loaf. Toscanose. Contains plagio- 
clase, biotite, and quartz, in a groundmass of quartz and orthoclase. 
P. R. C. 509. 
C. Quartz-porphyrite, Chicago Mountain. Lassenose. Contains 
plagioclase, orthoclase, biotite, and quartz. P. R. C. 508. 
Si0 2 .. 
A1A- 
Fe 2 3 . 
FeO.. 
MgO . 
CaO.. 
Na 2 0. 
H 2 at 110 c 
Ti0 2 . 
P 2 5 - 
MnO 
SrO. 
BaO. 
Li 2 
C0 2 . 
63.66 
17.05 
1.97 
2.62 
1.99 
3.89 
4.13 
3.09 
1.19 
undet. 
.27 
.14 
.08 
100. 08 
]'.. 
67.29 
15.78 
1.86 
1.97 
.72 
2.36 
3.77 
3.55 
2.10 
none 
.28 
.21 
none 
trace 
.27 
100. 16 
c. 
68.30 
16.24 
1.60 
1.63 
1.05 
2.79 
3.90 
3.52 
.71 
undet. 
.13 
.12 
.04 
trace 
trace 
100. 03 
