118 
ANALYSES OF ROCKS, U. S. GEOLOGICAL SURVEY. 
[BULL. 168. 
J. Granite, Boulder type, near Boulder. Near adamellite. Con- 
tains quartz, feldspar, black mica, and dark-green hornblende. Has 
an unusual amount of plagioclase. 
K. Bluebird granite, Nettie mine, Butte district. An aplite. Con- 
tains orthoclase and quartz, with a little plagioclase and a sprinkling 
of biotite. 
L. Same rock and locality as K. Analysis by W. F. Hillebrand, 
record No. 1692. 
M. Diorite, Red Mountain, east of Butte. Contains pale-green to 
colorless hornblende, plagioclase varying from labradorite to albite, 
some orthoclase, and a little quartz. Biotite, apatite, and magnetite 
also occur. 
N. Diorite, Red Mountain. Contact of granite with limestones. 
Consists mainly of green hornblende and "basic" plagioclase. Little 
quartz present. 
O. Quartz-monzonite, Red Rock Creek, north of Butte. Contains 
hornblende, augite, biotite, plagioclase, and orthoclase, with a little 
magnetite and apatite. 
Analyses J, K, M, N, and O by H. N. Stokes, record Nos. 1686, 1787. 
J. 
K. 
L. 
M. 
N. 
0. 
Si0 2 
67.12 
15.00 
1.62 
2.23 
1.74 
3.43 
2.76 
4.52 
.09 
.58 
.48 
.15 
none 
.06 
.03 
.07 
trace 
76.87 
12.52 
.67 
none 
.09 
.49 
2.47 
5.78 
.25 
.52 
.11 
.05 
77.05 
12.84 
.56 
.14 
trace 
.57 
2.81 
5.52 
.22 
.48 
.12 
none 
56.41 
17.62 
1.24 
3.55 
3.97 
8.66 
3.25 
2.61 
.14 
.76 
.68 
.49 
49.22 
12.02 
2.77 
8.80 
9.29 
10.56 
1.90 
1.70 
.27 
1.63 
.95 
.43 
61.64 
15.63 
3.39 
2.69 
2.82 
4.90 
2.64 
3.72 
.28 
.91 
.71 
.21 
trace 
.04 
.04 
.08 
trace 
A1 2 3 
Fe 2 3 -- - 
FeO 
MgO 
CaO 
Na 2 
K 2 
HjOatllO ... 
H 2 above 110° 
Ti0 2 
P 2 5 
Cr.,0, 
MnO 
trace 
none 
none 
trace 
| trace 
none 
none 
none 
none 
trace 
.08 
.08 
.09 
none 
none 
none 
.07 
trace 
.03 
.03 
trace 
.05 
.04 
.08 
SrO 
BaO 
Li 2 
S 
so 3 
trace 
none 
CI 
99.88 
99.82 
100. 31 
99.70 
99.77 
99.70 
