IGNEOUS AND CRYSTALLINE ROCKS. 
155 
11. BITTERROOT RANGE. 
Quartz-monzonite, near head of Mill Creek. Toscanose. To be 
described b/^ Lindgren in a forthcoming professional paper. Analysis 
by W. F. Hillcbrand, record No. 1921. Contains quartz, potash 
feldspar, plagiocla.se, biotite, apatite, titanite, and magnetite. 
Si0 2 -.. ... 72. 07 
Al A 15-51 
Fe/) :! 
FeO. 
MgO. 
CaO. 
Na 2 
Other elements not looked for. 
.31 
1.01 
.35 
1.93 
4.02 
4.09 
H 2 at 105° .... 
H 2 above 105° 
Ti0 2 
P 2 5 
03 
30 
16 
11 
MnO trace 
COo none 
99.89 
12. MARYSV1LLE DISTRICT. 
Rocks described by Joseph Barrell, but descriptions hitherto unpub- 
lished. Analyses by George Steiger, record No. 2021. 
A. Hornblende-mica-diorite, near West Belmont mine, east slope 
of Mount Belmont. Andose-'shoshonos$. Contains feldspars, 60 per 
cent; hornblende, 35 per cent; and small amounts of quartz, magnetite, 
biotite, augite, and apatite. 
B. Horn blende-porphy rite, north slope of the town of Bald Butte. 
Andose. Contains feldspar, largely oligoclase, about 75 per cent; 
and hornblende, 23 per cent; with secondary hornblende, calcite and 
chlorite. 
C. Quartz-diorite, road up Woodchopper Gulch. Tonalose. Typical 
of the Marysville batholith. Contains andesine, 52 per cent; quartz, 
31 per cent; orthoclase, 11 per cent; and minor biotite, hornblende, 
magnetite, titanite, and apatite. 
A. 
B. 
C. 
Si0 2 
52.07 
15. 99 
4.77 
5.59 
4.54 
7.50 
2.97 
2.79 
.34 
1.60 
1.08 
none 
.40 
56.88 
15. 61 
2.95 
2.34 
6.35 
5.23 
3.59 
2.39 
.67 
3. 03 
.49 
none 
.13 
63.55 
ALU, 
16.57 
Fe 2 0, 
2.36 
FeO 
1.98 
MgO 
1.53 
CaO \ . . 
4.69 
Na 2 
3.78 
K 2 
2.78 
H 2 Oat 105° 
.31 
H 2 above 105° 
1.11 
Ti0 2 
.42 
C0 2 
.69 
P 2 Or 
21 
so/ 
.06 
MnO 
.13 
BaO 
.15 
SrO 
.04 
99.64 
99.66 
100. 36 
