IGNEOUS AND CRYSTALLINE ROCKS. 93 
G iH. I J 
1 Oa soi. iictercrearercrore memnedere anes erates, aples ont ts alt AW OO 40.31 | 49.42 | 36.91 60. 84 
203. 12.11 13. 58 6. 54 16. 36 
Fe203. 8. 67 3.98 | 19. 43 2. 40 
FeO. 40 3. 59 . 67 3. 23 
MgO 2. 65 5. 06 1.07 3.85 
CaO... 33. 61 18.15 | 31.09 4. 96 
NaO... 79 2.22 | trace 2.90 
K30...... gcc 12 1. 42 18 4.10 
H20 at 105 23 28 -70 48 
22 50 1. 57 1.03 
78 71 |undet. | undet. 
11. BITTERROOT RANGE. 
Quartz monzonite, near head of Mill Creek. Toscanose. Described by Lindgren in 
P.P.27. Analysis by W. F. Hillebrand, record No. 1921. Contains quartz, potash, 
feldspar, plagioclase, biotite, apatite, titanite, and magnetite. P. R. C. 1519. 
Other elements not looked for. 
12. MARYSVILLE DISTRICT. 
Rocks described by Joseph Barrell, in P. P.57. Analyses by George Steiger, record 
No. 2021. 
A. Hornblende microdiorite, near West Belmont mine, east slope of Mount Belmont. 
Andose-shoshonose. Contains feldspars, 60 per cent; hornblende, 35 per cent; and 
small amounts of quartz, magnetite, biotite, augite, and apatite. 
B. Hornblende porphyrite, north slope of the town of Bald Butte. Andose. Con- 
tains 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. Yellowstonose. 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. 
Ke! 
H:0 at 105° 
