124 
ANALYSES OE BOOKS, IT. S. GEOLOGICAL SURVEY. [no. 228. 
U. Hornblende-mica-andesite, Crescent Hill. Yellowstonose. Analy- 
sis by Whitfield, No. 132, hitherto unpublished. Reported by Iddings 
as containing oligoclase-andesine, biotite, and subordinate decom- 
posed hornblende, in a groundmassof feldspar and quartz, with a little 
magnetite and biotite. 
V. Hornblende -andesite, Tower Creek. Dacose. Analysis by 
Gooch, No. 117, hitherto unpublished. Reported by Iddings as con- 
taining plagioclase, hornblende, and a little augite. 
W. Pyroxene-andesite, Agate Creek. Tonalose. Analysis by Whit- 
field, No. 432, hitherto unpublished. Reported by Iddings as contain- 
ing augite, hypersthene, labradorite, and magnetite, in a glassy 
microlitic groundmass. 
X. Rhyolitic perlite. Toscanose. Described by Iddings, Bull. 150, 
p. 153. Analysis by H. N. Stokes, No. 1311. From a bluff opposite 
the Midway Geyser Basin. Reported by Iddings as containing quartz, 
sanidine, plagioclase, and rarel} r augite and magnetite, with micro- 
scopic zircon and apatite, in a glassy groundmass. P. R. C. 61. 
u. 
V. 
W. 
X. 
Si0 2 
64.61 
18.62 
2.78 
.95 
.85 
4.20 
4.37 
2.36 
. 93 
none 
.30 
trace 
.01 
trace 
trace 
.25 
61. 56 
14.73 
4.47 
1.23 
3. 57 
4.87 
5.10 
2.24 
1.42 
.87 
.04 
. 34 
61.45 
15. 07 
4.46 
1.18 
3.02 
5.37 
4.00 
1.22 
1.23 
2.80 
trace 
none 
.05 
.29 
73. 84 
A1 2 3 
12.47 
Fe 2 0, 
.32 
I ( < ) 
.90 
MgO 
.25 
CaO 
1.08 
Na 2 
2.88 
K 2 
5. 38 
H 2 
2.76 
Ti0 2 
r,<>, 
MnO 
trace 
Li 2 
SO, 
CI 
co 2 
100. 23 
100. 44 
100. 14 
99.88 
