CLARKE.] 
IGNEOUS AND CRYSTALLINE ROCKS. 
183 
U. Hypersthene-andesite, 1 mile southwest of Thumb, head of Bailey 
Creek, near Lassen Peak. Abundant but inconspicuous plagioclase 
and hypersthene, in a microlitic groundmass containing many small 
crystals of plagioclase. Analysis by W. F. Hillebrand, record No. 675. 
V. Hypersthene-andesite, west summit of Crater Peak, Shasta 
County. Microphenociysts of feldspar and hypersthene in a ground- 
mass consisting largely of the same minerals, with some amorphous 
matter. Analysis by Hillebrand, No. 679. 
W. Hypersthene-andesite, north slope of Crater Peak. Phenoervsts 
of plagioclase and hypersthene in a groundmass containing much dark 
amorphous matter. Analysis by Hillebrand, No. 680. 
X. Secretion in W. Composed chiefly of plagioclase, hypersthene, 
and a globulitic base. Analysis by Hillebrand, No. 681. 
Y. Andesitic tuff, Stillwater Creek, 8 miles northeast of Redding. 
Contains plagioclase, hornblende, rare hypersthene, magnetite, and 
glass. Fragments of andesite are inclosed. Analysis by W. H. Mel- 
ville, record No. 1346. Described by Diller in Bull. 150, p. 211. 
Rocks dried at 100° to 110° before analysis. 
Si0 2 . 
ALA 
FeA 
FeO. 
MgO 
CaO. 
Na 2 
K 2 0. 
H 2 0. 
Ti0 2 
PA 
OA 
MnO 
SrO. 
BaO. 
Li 2 
u. 
v. 
59.84 
16.81 
1.88 
3.60 
3.85 
6.30 
3.63 
2.13 
1.04 
.57 
.19 
trace? 
.14 
.02 
.07 
trace 
100. 07 
68.12 
16. 24 
1.26 
2.08 
1.35 
3. 80 
3.89 
2.54 
.40 
.25 
.14 
none 
.10 
.02 
.09 
trace 
w. 
100. 28 
61. 17 
17.74 
1.78 
3.51 
2.76 
5. 90 
3.79 
1.71 
.83 
.45 
.14 
none 
.12 
.04 
.06 
trace 
100.00 
53. 85 
18.53 
1.96 
5. 30 
5.88 
9.66 
2.98 
.74 
.45 
.50 
.05 
trace 
.12 
.04 
.03 
trace 
100. 09 
69.51 
15.61 
.56 
1.27 
.61 
2.80 
3.43 
2.81 
3.63 
trace 
100. 23 
