IGNEOUS AND CRYSTALLINE ROCKS. 79 
a Other sulphides than pyrite are present. 
3. BOULDER BATHOLITH. 
Rocks collected by W. H. Weed, who supplies the petrographic data. 
A. Quartz monzonite, or ‘‘ Butte granite,’’ from the Frohner mine, 10 miles south 
of Helena. Harzose. Contains quartz, andesine, orthoclase, hornblende, and biotite, 
with minor accessories. 
B. Granite, Boulder type, near Boulder. Near adamellite. Toscanose. Contains 
quartz, feldspar, black mica, and dark-green hornblende. Has an unusual amount 
of plagioclase. 
C. Diorite, Red Mountain. Andose. Contains pale-green to colorless hornblende, 
plagioclase varying from labradorite to albite, some orthoclase, and a little quartz. 
Biotite, apatite, and magnetite also occur. 
D. Diorite, Red Mountain. Kentallenose. Contact of granite with limestones. 
Consists mainly of green hornblende and ‘‘basic” plagioclase. Little quartz present. 
E. Quartz monzonite, Red Rock Creek. Harzose. Contains hornblende, augite, 
biotite, plagioclase, and orthoclase, with a little magnetite and apatite. 
Analyses by H. N. Stokes, record Nos. 1686, 1787. 
ao 1 BE Cc. D E 
67.12 | 56. 41 49. 22 61. 64 
15.00 | 17.62} 12.02 15. 63 
1. 62 1.24 2.77 3. 39 
2. 23 3.55 8. 80 2.69 
1.74 3.97 9. 29 2.82 
3. 43 8.66 | 10. 56 4.90 
2.76 3. 25 1.90 2. 64 
4. 52 2. 61 1.70 3.72 
-09 -14 2 +28 
- 58 wi Gi 1. 63 .91 
- 48 - 68 95 71 
15 49 43 24 
MODE |e.sy53-se:0aearersmsee trace 
06 -08 | trace 0. 
03 - 08 ‘ 04 
07 09 03 08 
trace | none | trace trace 
Saaciosise: none 05) eseccese 
trace | none -04 none 
scapes 07 HOB cdccuia 
99.88 | 99.70 | 99.77 99. 70 
