132 
ANALYSES OF ROCKS, U. S. GEOLOGICAL SURVEY. 
[NO. 228. 
2. BUTTE DISTRICT. 
Rocks received from W. H. Weed and G. W. Tower. Some of the 
granite rocks are described by Weed in Journ. Geol., vol. 7, p. 737. 
All the rocks are to be described in a forthcoming- monograph on 
Butte. 
A. Butte granite. Amiatose. A quartz-monzonite, variety bana- 
tite, from Walkerville Station. Contains quartz, andesine, orthoclase, 
hornblende, and biotite, with a little titanite, apatite, and magnetite. 
B. Biotite from A. 
C. Amphibole from A. 
Analyses A, B, C, by H. N. Stokes, record Nos. 1686, 1808. 
D. Butte granite, Gagnon mine, Butte. Amiatose. 
E. Butte granite, Atlantic mine, Butte. Harzose. 
F. Butte granite, Alice mine, Butte. Harzoxe. Analyses D, E, and 
F, by W. F. Hillebrand, record No. 1692. Mineralogically the rocks 
are like A and D. 
Si0 2 ... 
A1,0 3 
Fe 2 3 
FeO 
MgO 
CaO 
Na 2 
K 2 
H 2 OatllO°.._. 
H 2 above 11 C 
Ti0 2 
Zr0 2 
C0 2 
PA 
Mn( ) 
NiO 
BaO 
SrO 
Li 2 
so 3 
FeS 2 
CI 
F 
Cu 
LessO. 
63.88 
15.84 
.09 
.02 
trace 
.34 
trace 
99.82 
35. 79 
13.70 
5.22 
13.72 
12.13 
.05 
.15 
9. 09 
1.21 
3.64 
3.51 
.10 
.19 
.13 
none 
trace 
20 
76 
99. 59 
.37 
99. 22 
45. 73 
6.77 
4.94 
10. 39 
12.32 
11.25 
.77 
1.22 
.49 
2.29 
1.43 
none 
none 
trace 
28 
98.77 
.12 
64.05 
15.38 
2.20 
2.74 
2.08 
4.30 
2.74 
4. 00 
.27 
.83 
.60 
(?) 
.35 
.21 
.11 
trace? 
.08 
.04 
trace 
.07 
005 
100. 055 
98. 61 
64.34 
15. 72 
62 
94 
17 
24 
76 
4.04 
.25 
.76 
.53 
.02 
.03 
.14 
.12 
trace? 
.06 
.03 
trace 
03 
005 
99. 805 
63.87 
15.39 
1.93 
3.08 
2.23 
4.30 
2.76 
4.18 
.19 
.69 
.65 
.03 
.15 
.17 
.11 
trace 
.07 
.04 
trace 
.07 
.005 
). 915 
