CLARKE.] 
IGNEOUS AND CRYSTALLINE ROCKS. 
215 
P. Hypersthene-andesite, 1 mile west of summit on BidwelPs road, 
Butte County. Andose. Rich in small phenocrysts of plagioclase 
and pyroxene, mostly hypersthene, in a groundmass of the same min- 
erals, with magnetite, and probably some amorphous matter. Analy- 
sis by W. F. Hillebrand, record No. 410. 
Q. Hypersthene-andesite, old crater at head of Mill Creek, u 1 n<l<>se. 
Contains small phenocrysts of plagioclase and hypersthene, in a 
groundmass of plagioclase, pyroxene, magnetite, etc. Some greenish 
pseudomorphs suggest former olivine. Analysis by T. M. Chatard, 
record No. 409. 
R. Hypersthene-andesite, 2 miles south of Suppans Mountain, 
Tehama County. Tonalose. Abundant plagioclase and hypersthene, 
with traces of hornblende, in a microlitic groundmass. Analysis by 
Hillebrand, No. 672. 
S. Secretion in R. Bandose. Composed chief!} 7 of plagioclase and 
hypersthene, with some quartz and amorphous matter. Analysis by 
Hillebrand, No. 673. 
T. Hypersthene-andesite, west base of Suppans Mountain, near 
Lassen Peak, Tehama County. Tonalose. Contains numerous micro- 
scopic crystals of plagioclase and hypersthene, in a microlitic ground- 
mass. Analysis by Hillebrand, No. 676. 
Rocks dried at 100° to 1 10° before analysis. 
p. 
Q. 
R. 
s. 
T. 
SiO, 
55. 20 
18.68 
3.14 
4.42 
4.59 
8.02 
3. 66 
1.01 
.51 
.92 
.24 
.14 
.02 
.03 
none 
57. 11 
17.78 
3. 54 
2.74 
3.41 
7.21 
3. 81 
1 . 86 
.98 
.95 
.26 
.33 
trace? 
.03 
63. 47 
L6.75 
2.15 
" 2.75 
3. 04 
5. 72 
;;. 94 
1.62 
.55 
.37 
.13 
.09 
.04 
.04 
trace 
57. 04 
19. 11 
4.37 
2.48 
8. 94 
7.34 
8. 48 
1. 16 
1.09 
.47 
.08 
.12 
.02 
trace? 
trace 
58. 08 
ALO, 
18.37 
Fe A 
2.92 
FeO 
3. 38 
MgO 
CaO.... 
3. 35 
7.05 
Na 2 
K 2 
8. 66 
1.33 
H 2 
1.09 
Ti0 2 
.44 
PA 
.16 
MnO 
.13 
SrO 
.02 
Ba() 
.03 
Li 2 
trace 
100. 58 
100. 01 
100. 66 
100.70 
M io.OI 
