90 
ANALYSES OF EOCKS, IT. S. GEOLOGICAL SURVEY. 
[bull. 16$ 
2. SEPULCHRE MOUNTAIN. 
Rocks described by Iddings, 12th Ann., p. 633. Also in Bull. Phil. 
Soc. Washington, vol. 11, p. 210, and in Mon. XXXII, Pt. II, 
A. Pyroxene-andesite. Essentially composed of augite, hyper- 
sthene, and plagioclase. Analysis by J. E. Whi^ld, record No. 923. 
B. Pyroxene-andesite. Composition like A. Analysis by Whit- 
field, No. 923. 
C. Hornblende-andesite. Essentially plagioclase and hornblende. 
Analysis by Whitfield, No. 922. 
D. Hornblende-pyroxene-andesite. Contains augite, hypersthene, 
plagioclase, and hornblende. Analysis by T. M. Chatard, record No. 
712. 
E. Hornblende-pyroxene-andesite. Minerals as in D, with magne- 
tite also. Analysis by Chatard, No. 712. 
A. 
B. 
c. 
D. 
E. 
Si0 2 
55. 83 
17.11 
4.07 
3.75 
5.05 
7.40 
2.94 
1.71 
| 1.28 
1.05 
.21 
57. 17 
17.25 
2.48 
4.31 
4.83 
6.61 
3.44 
2.03 
| 1.20 
1.03 
.05 
55.92 
17.70 
3.16 
4.48 
4.34 
5.90 
4.08 
2.24 
| 1.42 
.94 
.18 
56.61 
13.62 
5.89 
2.60 
5.48 
6.61 
3.13 
2.71 
1.20 
1.07 
.79 
.06 
.05 
.35 
.14 
Trace 
60.30 
16.31 
4.35 
1.41 
2.39 
5.62 
3.99 
2.36 
.64 
1.86 
.76 
.20 
trace ? 
.13 
.15 
Trace 
A1 2 3 
Fe 2 3 
FeO 
MgO 
CaO 
Na 2 
K 2 
H 2 Oatl05° 
H 2 above 105° 
Ti0 2 
P,0< 
Cr 2 3 
MnO 
none 
none 
trace 
BaO 
SrO 
Li 2 
none 
trace 
none 
trace 
trace 
trace 
.09 
trace 
none 
SO, 
(?) 
.10 
CI 
100. 40 
100. 40 
100. 45 
100. 31 
' 100.57 
