174 
ANALYSES OF ROCKS, U. S. GEOLOGICAL SURVEY. 
[BULL. 168. 
F. Typical hypersthene-andesite, San Francisco Mountains. Not 
described. Analysis by T. M. Chatard, record No. 270. 
G. Recent lava, 2* miles south of Mount Trumbull. Not describe . 
Analysis by L. G. Eakins, record No. 1024. 
Si0 2 . 
A1 2 3 
Fe 2 O s 
FeO. 
MgO 
CaO. 
Na 2 
K 2 0. 
H 2 0. 
Ti0 2 . 
P 2 5 . 
MnO 
99.78 
64.82 
45.30 
18.27 
14. 95 
3.48 
1.98 
.56 
9.32 
.85 
8.29 
2.89 
8.87 
5.05 
4.27 
2.67 
1.27 
.20 
.85 
.56 
2.66 
.23 
2.23 
.20 
trace 
99.99 
NEVADA. 
1. ROCKS FROM WASHOE. 
Described by Hague and Iddings, Bull. 17. Analyses by F. A. 
Gooch, record Nos. 119, 129. FeO not separately determined. 
A. Rhyolite, south-southeast of McClellan Peak. Contains feld- 
spars, orthoclase predominating over plagioclase, quartz, mica, and 
hornblende. 
B. Dacite, spur northeast of McClellan Peak. More plagioclase 
than orthoclase, much mica, less hornblende, little quartz. 
Si0 2 -... 
A1 2 3 ... 
Fe 2 3 ... 
MgO ... 
CaO.... 
Na,0... 
K 2 0.... 
Ignition 
99.83 
73.07 
69.96 
11.78 
15.79 
2.30 
2.50 
.39 
.64 
2.02 
1.73 
1.19 
3.80 
6.84 
4.12 
2.24 
1.53 
100. 07 
