216 
ANALYSES OF ROCKS, U. S. GEOLOGICAL SURVEY, 
[BULL. 168. 
L. Serpentine. 
M. Talc-like, yellowish-green serpentine. 
N. Weathered serpentine. 
O. Olive colored, probably serpentine. 
Samples H, I, and J are from near Bagley Creek; K, L, M, and N 
from near Arroyo del Cerro; O from Ferguson ravine. M and O 
carry considerable chromite. 
Si0 2 
A1 2 3 
Fe 2 3 
FeO 
MgO 
CaO 
Na 2 
K 2 
H 2 Oat 100°... 
H 2 above 100 c 
P-A 
Cr 2 3 
NiO 
MnO 
S0 3 
34.84 
.42 
6.08 
1.85 
30.74 
7.02 
.42 
.07 
1.67 
15.72 
.04 
.68 
trace 
.01 
).56 
32.27 
11.45 
trace 
5.05 
33.30 
.41 
trace 
trace 
.44 
12.40 
trace 
5.19 
.19 
trace 
100. 70 
41.52 
1.57 
3.50 
1.07 
36.84 
.44 
3.32 
12.51 
29 
101.06 
o. 
30.98 
1.04 
4.88 
2.01 
38.44 
.22 
.40 
.16 
.39 
20.43 
trace 
.34 
42 
44 
100. 15 
