IGNEOUS AND CRYSTALLINE ROCKS. 
17 ( ,> 
8. WEST ELK MOUNTAINS. 
Rocks described by Cross in 11th Ann., p. 165. 
A. Hornblende-mica-porphyrite, Cliff Creek. Adamellose. Con- 
tains plagioclase, hornblende, and biotite, in a groundmass of quartz, 
feldspar, and mica. Analysis by W. F. Hillebrand, record No. 1429. 
B. Porphyrite, Storm Ridge. Yellowstonose. Contains plagioclase, 
biotite, hypersthene, hornblende, and augite, in a groundmass of quartz 
and orthoclase. Analysis by L. G. Eakins, record No. 1238. P. R. C. 
517. 
C. Porphyrite-diorite, Mount Marcellina. Yellowstonose. Contains 
plagioclase, hornblende, and a little biotite, in a groundmass of quartz 
and orthoclase. Analysis by T. M. Chatard, record No. 1238. P. R. 
C. 516. 
I). Quartz-porphyrite, Mount Carbon. Amiatose. Contains pla- 
gioclase, orthoclase, biotite, hornblende, augite, and quartz. Analysis 
by Chatard, record No. 1238. P. R, C. 518. 
E. Quartz-porphyrite, Crested Butte. Lassenose. Contains plagio- 
clase, orthoclase, hornblende, biotite, quartz, and a little augite. 
Analysis made by Eakins in the Denver laboratory. P. R. C. 515. 
Si0 2 . 
AU> :( 
Fe 2 3 
FeO. 
Mg( ) 
CaO. 
Na,0 
K,0. 
H 2 0at 100° 
H,( ) above 100° 
Ti(), 
PA 
Mn' ) 
Sr() 
BaO 
Li,<> 
63.05 
15.58 
2.92 
2.11 
1.70 
4.15 
3.77 
3. 66 
.55 
1 . 38 
.60 
.27 
.12 
.07 
.13 
trace 
100. 06 
on 
100. 28 
62. 85 
16.21 
3.08 
1.46 
1.47 
4.72 
3. 49 
3.10 
.29 
2.03 
.41 
.48 
. 15 
II 
99. ^ 
D. 
65.36 
15.48 
3. 09 
1.21 
1.53 
4.14 
3.58 
3.41 
.82 
.70 
.52 
.25 
.19 
OS 
100.36 
65.71 
IS. 30 
1.19 
1.53 
.98 
2.17 
5.00 
3. 95 
1.39 
undet. 
(12 
100.24 
