IGNEOUS AND CRYSTALLINE ROCKS. 
193 
F. Diabase-porphyry, dike east of Milton. Contains labradorite 
and other plagioclase, augite, and hornblende, the last mineral being 
perhaps secondary. P. R. C. 733. 
G. Hypersthene-andesite, point northeast of Goodyears Bar. Con- 
tains plagioclase and rhombic pyroxene, a little augite, and scales 
which seem to represent former biotite, now replaced by magnetite. 
P. R. C. 731. 
H. Hornblende-pyroxene-andesite, dike southeast of Poker Flat. 
Contains plagioclase, augite, hornblende, magnetite, some glass, and 
occasional quartz. P. R. C. 736. 
1. Quartz-bearing andesite, northwest of Downieville. Contains 
plagioclase, augite, enstatite, magnetite, occasional quartz, and prob- 
ably glass. P. R. C. 753. 
Si0 2 .. 
A1 2 8 - 
Fe 2 3 . 
FeO.. 
MgO. 
CaO.. 
Na 2 0. 
H 2 at 100° . . . 
H 2 above 100 c 
Ti0 2 
PA 
Cr 2 3 ... 
NiO 
MnO 
SrO 
BaO 
S0 3 
51.27 
12.14 
2.51 
6.71 
10.88 
10.32 
2.00 
1.63 
.17 
1.16 
.60 
.21 
.04 
.21 
trace? 
.07 
trace 
99.92 
66.94 
16.49 
1.41 
1.87 
1.98 
4.77 
3.88 
1.65 
.35 
.22 
.30 
.12 
.13 
.05 
.07 
trace 
100. 23 
50.34 
17.61 
3.63 
2.28 
3.50 
6.45 
3.40 
1.94 
.64 
.74 
.32 
.25 
.12 
.04 
.11 
trace 
100. 3/ 
I. 
60.02 
16.07 
2.17 
3.46 
4.57 
7.01 
3.55 
1.59 
.24 
.45 
.42 
.17 
trace 
.10 
trace 
.08 
none 
.06 
5)9.96 
Bull. 168- 
-13 
