IGNEOUS AND CRYSTALLINE ROCKS. 
121 
G. Porphyrite, intrusive sheet, north of Shields River Basin. Con- 
tains plagioclase, hornblende, and biotite, in a groundmass of plagio- 
clase, a little orthoclase, augite, hornblende, and magnetite. 
H. Porphyrite, intrusive sheet, northern part of the mountains. 
Contains brown hornblende, green augite, and plagioclase, in a ground- 
mass of plagioclase, augite, and magnetite, with accessory apatite. 
I. Syenite, ridge north of Shields River Basin. Contains horn- 
blende, green augite, and anorthoclase, With accessory sphene, apatite, 
and magnetite. 
J. Diabase-porphyrite (?), dike south of Shields River Basin. Con- 
tains labradorite and decomposed augite in a groundmass of plagio- 
clase, epidote, and chlorite. 
K. Diorite-porphyrite, Big Timber Creek. Contains labrador 
augite, hornblende, biotite, orthoclase, quartz, magnetite, and apatiio. 
L. Quartz-diorite, main stock on Sweet Grass Creek. . Contains 
hornblende, biotite, augite, labradorite, orthoclase, and quartz, with 
accessory apatite, magnetite, olivine, and hypersthene. 
G. 
H. 
I. 
J. 
K. 
L. 
Si0 2 
56. 75 
16.40 
4.78 
3.10 
3.22 
5.34 
4.19 
3.36 
.40 
.82 
.86 
.52 
.17 
.10 
.33 
trace? 
54.69 
16.53 
4.54 
2.83 
2.99 
5.34 
5.19 
3.93 
.32 
1.05 
.91 
.73 
.07 
.06 
.37 
trace? 
trace 
.83 
58.28 
17.89 
3.20 
1.73 
1.51 
3.69 
5.89 
5.34 
.17 
.98 
.64 
.26 
.06 
.05 
.36 
trace 
58.28 
19. 37 
1.35 
2.98 
1.30 
4.78 
4.40 
3.75 
.44 
1.78 
.96 
.35 
.07 
.09 
.25 
trace? 
54.56 
17. 58 
4.30 
4.98 
2.86 
6.00 
4.43 
2.70 
.02 
.38 
1.34 
.60 
.06 
.08 
.27 
trace 
53.48 
19.35 
2.37 
4.90 
3.67 
7.55 
4.07 
1.41 
.16 
.80 
1.07 
.62 
.06 
.11 
.19 
trace? 
ALOo 
Fe 2 3 
FeO 
MgO 
CaO 
Na ? 
K 2 
H 2 OatllO° .. 
H 2 above 110° 
Ti0 2 
P 2 5 
MnO 
SrO 
BaO 
Li 2 
CI.. 
co 2 
.33 
.08 
1 
100. 34 
100. 38 
100. 05 
100. 48 
100. 16 
99.89 
