222 
ANALYSES OF ROCKS, U. S. GEOLOGICAL SURVEY. 
[BULL. 168. 
D. Rhyolite, water's edge, head of Cleetwood Cove. Contains pla- 
gioclase, hypersthene, brown hornblende, and magnetite, in a feld- 
spathic groundmass of trachytic type. 
E. Hypersthene-augite-andesite, large dike transsecting the north- 
western portion of the crater rim. Contains plagioclase, hypersthene, 
augite, and magnetite in a groundmass having a moderate amount of 
glass. 
F. Hypersthene-augite-andesite, west edge of Wizard Island. Same 
minerals as E. 
A. 
B. 
c. 
r>. 
E. 
F. 
Si0 2 
70.77 
14.83 
1.35 
1.25 
.64 
2.12 
5.07 
2.68 
.07 
.33 
.38 
.13 
.05 
none 
.02 
.08 
trace 
.11 
68.17 
15.60 
2.31 • 
.94 
1.02 
2.76 
5.15 
2.46 
.09 
.45 
.54 
.13 
none 
none 
.03 
.06 
trace 
trace 
71.87 
14. 53 
1.28 
1.02 
.48 
1.59 
5.08 
2.84 
.06 
.22 
.41 
.10 
.04 
none 
.03 
.08 
trace 
trace 
70.10 
15.18 
1.78 
1.09 
.74 
2.27 
5.15 
2.58 
.10 
.19 
.48 
.13 
.04 
none 
.03 
.08 
trace 
.03 
60.09 
17.85 
2.03 
3.45 
3.50 
6.28 
4.17 
1.31 
.12 
.26 
.54 
.23 
none 
.05 
.05 
.05 
trace 
trace 
59. 39 
18.45 
1.79 
3.90 
3.13 
6.29 
4.29 
1.29 
.10 
.42 
.41 
.22 
none 
none 
.04 
.05 
trace 
trace 
A1,0 :! - 
Fe 2 3 
FeO 
MgO 
CaO 
Na 2 
K 2 
H 2 Oatll0°... 
H 2 above 110° 
Ti0 2 
P 9 0, 
Zr0 2 
MO 
SrO 
BaO 
Li 2 
CI 
99.88 
99.71 
99.63 
99.97 
99.98 
99.77 
Traces of manganese in all. Fluorine not sought for. No C0 2 , S, S0 3 , or Cr 2 3 
in any. 
G. Hypersthene-augite-andesite, crater rim, just south of "The 
Watchman." Same minerals as F. 
H. Hypersthene-augite-andesite, Palisades, under Round Top, north- 
east portion of the rim. Contains plagioclase, hypersthene, augite, and 
magnetite. 
I. Hypersthene-augite-andesite, lake level, under Llao Rock. Same 
minerals as H. 
J. Basalt, base of Red Cone. Contains plagioclase, augite, olivine, 
and magnetite, with some glass base. 
