158 
ANALYSES OF ROCKS, U. S. GEOLOGICAL SURVEY. 
[no. 228. 
I. Quartz-monzonite, Schafer Butte, Boise County. Lassenose. 
Contains quartz, orthoclase, oligoclase, biotite, apatite, titanite, and 
magnetite. Analysis by George Steiger, record No. 1802. 
J. Granodiorite, Silver Wreath mine, Boise County. Yellowstonose. 
Contains orthoclase, oligoclase, apatite, biotite, titanite, and magnetite. 
Described in 18th Ann., Part III, p. 612. Sp. gr., 2.714, 23°. 
K. Same as J, but in altered condition. Also described in 18th Ann. 
Contains sericite, quartz, titanite, apatite, and pyrite, with carbonates 
of calcium, magnesium, and iron. Sp. gr., 2.771, 23°. 
Analyses J and K by George Steiger, record No. 1691. 
L. Volcanic sand, Nez Perces region. Collected by I. C. Russell. 
Analysis by W. F. Hillebrand, record No. 1906. 
M. Typical basalt, Cinder Buttes, west side of Snake River plains. 
Camptonose. Analysis b}^ W. F. Hillebrand, record No. 1950. Anal- 
ysis published by Russell in Bull. 199, but the mineralogical composi- 
tion of the rock is not given. Sp. gr., 2.907 at 21°. 
I. 
J. 
K. 
L. 
M. 
Si0 2 
69.56 
15.29 
.86 
2.06 
.69 
2.81 
3.97 
3.36 
| .86 
.55 
65.23 
16.94 
1.60 
1.91 
1.31 
3.85 
3. 57 
3.02 
.18 
.88 
.66 
66.66 
14. 26 
.67 
2.41 
.95 
3.37 
none 
4.19 
.36 
2.16 
.49 
68.95 
14.33 
1.17 
1.23 
.47 
2.13 
5.08 
2.58 
.28 
3.63 
.42 
.03 
51.14 
ALO, 
13. 95 
Fe 2 3 
2.15 
FeO 
12.97 
MgO 
2.21 
CaO 
6.56 
Na 2 
3.59 
K 2 
2.33 
H 2 at 105° 
.12 
H 2 above 105° 
.22 
Ti0 2 
2.41 
Zr0 2 
.12 
co 2 
.25 
.19 
trace 
3.67 
.17 
trace 
P 2 5 
.16 
.10 
trace 
1.59 
MnO 
.44 
MO 
trace 
BaO 
.19 
none 
.08 
trace 
trace 
trace 
? 
.25 
SrO 
trace 
Li 2 
none 
S 
none 
.95 
F 
10 
CI 
trace 
FeS 2 
.15 
V 2 3 
trace 
Less O 
100. 17 
99.78 
100. 11 
.24 
100. 48 
100. 30 
100. 07 
