128 
ANALYSES OF KOCKS, IT. S. GEOLOGICAL SURVEY. 
[NO. 228. 
D. Highly altered porphyrite?, hills 1 mile north of East Gallatin 
River, near Camp No. 6. Rock contains hornblende paramorphs after 
augite in a devitrified base, with amygdules of calcite, chloritic and 
ferruginous matter derived from porphyritic augite and olivine. The 
base is also filled with needles, which may be mica. Analysis by 
Eakins, record No. 820. P. R. C. 968. 
E. Lamprophyre, Cottonwood Creek. Monzonose. Contains por- 
phyritic augite and olivine in an indeterminate groundmass carrying 
augite, iron oxides, and mica. Analysis by Chatard, record No. 516. 
P. R. C. 979. 
F. Augite-porphyry, Cottonwood Creek. Shoshonose. Contains 
feldspars, augite, and brown mica, with iron oxides, apatite, glass, 
and secondary calcite and chlorite. Carries porphyritic plagioclase 
and augite. No unaltered olivine visible. Sp. gr., 2.785. Anah T sis 
by Eakins, record No. 819. P. R. C. 965. 
Si0 2 .. 
A1A. 
FeA 
FeO.. 
MgO . 
CaO.. 
Na 2 0. 
H 2 above 120 c 
Ti0 2 
PA 
Cr 2 3 
MnO 
BaO 
S0 3 
co 2 
I). 
41). 47 
12.15 
1.93 
4.07 
10.86 
9.30 
2.08 
2. 42 
4.14 
.21 
.37 
trace 
.10 
.03 
3.31 
E. 
51.65 
13.89 
2.70 
4.80 
11.56 
4.07 
2.99 
4.15 
1.30 
1.89 
.55 
.21 
.08 
.15 
.19 
.19 
100. 44 
100. 37 
F. 
52.33 
15.09 
4.31 
4.03 
6.73 
7.06 
3.14 
3.76 
2.68 
.14 
1.02 
.09 
.07 
100. 45 
