184 ANALYSES OF EOCKS, U. S. GEOLOGICAL SURVEY. [bull. 168. 
3d. basalts. 
The quartz-basalts are described by Diller in Bull. 79. That from 
Mitylene was analyzed for comparison with the Cinder Cone series. 
A. Quartz -basalt, Cinder Cone, 10 miles northeast of Lassen Peak. 
Contains plagioclase, pyroxene (mostly hypersthene), olivine, quartz, 
and much unindividualized base; the latter about 25 per cent. Mag- 
netite is also present; augite occurs sparingly. Analysis by W. F. 
Hillebrand, record No. 407. P. R. C. 96. Also described in Bull 
150, p. 252. 
B. Volcanic bomb from quartz-basalt, Cinder Cone. Analysis by 
Hillebrand, No. 665. 
C. Lapilli from quartz-basalt, Cinder Cone. Analysis by Hille- 
brand, No. 667. P. R. C. 96. Also described in Bull. 150, p. 249. 
D. Volcanic sand, one-half mile northeast of Cinder Cone. Analy- 
sis by Hillebrand, No. 663. 
E. White pumiceous inclosure from quartz-basalt, Cinder Cone. 
Analysis by Hillebrand, No. 664. Mainly glass. 
Rocks dried at 100° to 110° before analysis. 
A. 
57.25 
16. 45 
1.67 
4.72 
6.74 
7.65 
3.00 
1.57 
.40 
.60 
.20 
B. 
C. 
D. 
E. 
SiO, 
56.70 
15.75 
1.29 
5.32 
7.16 
7.67 
3.36 
1.56 
.30 
.65 
.20 
trace 
.19 
trace 
.03 
trace 
56.53 
17.50 
1.35 
5.03 
5.94 
8.07 
3.51 
1.55 
.27 
.54 
.15 
trace 
.12 
trace? 
trace 
trace 
55.93 
17.34 
1.50 
5.20 
7.29 
8.04 
3.32 
1.35 
.26 
undet. 
undet. 
79.49 
11.60 
.33 
.49 
.09 
1.64 
4.04 
1.52 
.68 
undet. 
undet. 
Al 2 O s 
Fe 2 3 
FeO 
MgO 
CaO 
Na 2 
K 2 
H 2 
Ti0 2 
P 2 0, 
Cr 2 3 
MnO 
.10 
trace 
.03 
none 
undet. 
(?) 
(?) 
(?) 
100. 23 
none 
(?) 
(?) 
(?) 
SrO 
BaO 
Li 2 
100. 38 
100. 18 
100. 56 
99.88 
