188 
ANALYSES OF ROOKS, U. S. GEOLOGICAL SURVEY. [bull. 168 
F. Rhyolite, 3i miles southwest of Grizzly Peak. Description fur 
nished by Turner. Contains sanidine, with less quartz and biotite 
in a glassy groundmass. Analysis by Hillebrand, record No. 1461 
P. R. C. 776. 
G. Hornblende-andesite, 4 miles from Pilot Peak. Described bj 
Turner in 14th Ann., p. 441. Contains plagioclase and hornblende ii 
a groundmass carrying grains of magnetite. Analysis by Hillebrand 
record No. 1432. P. R. C. 716. 
H. Hornblende-pyroxene-andesite, southwest base of Mount Ingalls 
Description supplied by Turner. Contains plagioclase, rhombic pyrox 
ene, augite, brown hornblende, and magnetite, with much glass in th< I 
groundmass. Analysis by Hillebrand, record No. 1456. P. R. C. 728 | 
I. Hypersthene-andesite, Franklin Hill. Description supplied ty 
Turner. Contains plagioclase, rhombic pyroxene, augite, and magnet 
ite. Probably no glass. Analysis by Hillebrand, record No. 1548 
P. R. C. 754. 
F. 
G. 
H. 
I. 
Si0 2 . 
71.39 ' 
14.13 
.63 
.37 
.08 
1.01 
2.89 
5.69 
.42 
3.32 
.17 
.03 
trace 
trace 
.09 
trace 
60.20 
17.21 
3.12 
2.69 
3.18 
6.04 
3.35 
1.44 
1.12 
1.18 
.57 
.17 
.12 
trace 
.11 
trace 
58. 47 
18.80 
3.34 
2.64 
2.69 
6.60 
3.58 
2.01 
.14 
.92 
.51 
.22 
.13 
.05 
.09 
trace 
56.88 
18.25 
2.35 
4.45 
4.07 
7.53 
3.29 
1.42 
.24 
.50 
.45 
.30 
.18 
.04 
.11 
trace 
A1 2 3 
Fe 2 3 
FeO 
MgO 
CaO 
Na 2 
K 2 
H 2 Oatl00° 
H 2 above 100° 
Ti0 2 
P 2 0* 
MnO 
SrO 
' BaO 
Li 2 
100. 22 
100. 50 
100. 19 
100. 06 
