120 
ANALYSES OF ROCKS, U. S. GEOLOGICAL SURVEY. 
[BULL. 168. 
3. CRAZY MOUNTAINS. 
The greater number of the rocks in this group were received from 
J. E. Wolff, who has supplied the petrographic data. The few excep- 
tions are properly indicated. The three tinguaites and the elseolite- 
syenite were described by Wolff and Tarr in Bull. Mus. Compar. Zool- 
ogy, vol. 16, No. 12, 1893, in a paper upon "Acmite-Trachyte from the 
Crazy Mountains." The renaming of these rocks is due to Wolff. The 
analyses, except when otherwise stated, are by W. F. Hillebrand, 
record No. 1438. 
A. Granitite, Big Timber Creek. Small dikes in main diorite stock. 
Contains quartz, orthoclase, plagioclase (oligoclase), and biotite. 
B. Hornblende-granitite, main stock, Big Timber Creek. Contains 
biotite, hornblende, quartz, orthoclase, and plagioclase (oligoclase). 
C. Granite-porphyry, intrusive sheet, north part of the mountains. 
Contains orthoclase, albite, quartz, biotite, and green hornblende in a 
groundmass of quartz and untwinned feldspar. 
D. Porphyrite, intrusive sheet, Sweet Grass Creek. Contains horn- 
blende and andesine in a groundmass of plagioclase, orthoclase, and 
quartz, with accessory magnetite. 
E. Porphyrite, dike in contact zone, Sweet Grass Creek. Contains 
brown hornblende, biotite, and labradorite in a groundmass of plagio- 
clase, biotite, and hornblende, with a little quartz and orthoclase. 
F. Porphyrite, intrusive sheet, middle peak of Three Peaks. Con- 
tains andesine, hornblende, augite, and biotite in a groundmass of 
plagioclase, orthoclase, and quartz. 
A. 
B. 
c. 
D. 
E. 
F. 
Si0 2 
74.37 
13.12 
.73 
.87 
.35 
1.26 
2.57 
6.09 
.05 
.25 
.29 
.06 
trace 
trace 
.10 
trace 
64.47 
15.45 
2.25 
2.25 
2.68 
3.63 
4.54 
3.19 
.05 
.63 
.75 
.22 
.06 
.04 
.23 
trace? 
69.93 
14.95 
1.78 
.55 
.60 
1.46 
5.30 
3.99 
.12 
.32 
.33 
.33 
trace 
.06 
.29 
trace 
66.28 
16.21 
.80 
2.06 
1.57 
3.53 
4.36 
3.20 
.12 
.78 
.50 
.20 
trace 
.05 
.34 
trace? 
64.49 
17.25 
.86 
2.42 
1.24 
3.79 
4.19 
4.15 
.06 
.54 
.,51 
.23 
trace 
.08 
.30 
trace 
61.08 
16.62 
2.87 
2.56 
1.65 
3.66 
4.75 
3.90 
.44 
.97 
.73 
.63 
trace 
.08 
.32 
trace 
A1 2 3 
Fe 2 3 
FeO 
MgO 
CaO 
Na 2 
K 2 
H 2 OatllO°... 
H 2 above 110° 
Ti0 2 
P 2 6 
MnO 
SrO 
BaO 
Li 2 
100. 11 
100. 44 
100. 01 
100. 00 
100.11 
100. 26 
