170 
ANALYSES OF ROCKS, U. S. GEOLOGICAL SURVEY. 
[NO. 228. 
V. Syenite, Silver Cliff. Monzonose. Contains orthoclase and 
plagioclase in nearly equal amounts, colored by ferric hydroxide, with 
amphibole, a little biotite, and secondary epidote, calcite, and chlorite. 
Sp. gr., 2.689, 20°. P. R. C. 71 and 520. 
W. Quartz-alunite rock, Democrat Hill. About two-thirds quartz 
and one-third alunite. Record No. 1126. P. R. C. 596. 
X. The same, Mount Robinson. About one-fourth alunite. Record 
No. 1248. P. R. C. 593. 
Y. Quartz-diaspore rock, Mount Robinson. About 18 per cent 
diaspore, the rest quartz. Record No. 1167. P. R. C. 594. 
Rocks W, X, and Y are also described in Amer. Journ. Sci., 3d 
series, vol. 41, p. 471. These three rocks are decomposition products 
of rhyolite. 
Si0 2 
Fe 2 3 - 
FeO.. 
MgO . 
CaO.. 
Na 2 0. 
K 2 0_. 
H 2 0. 
Ti0 2 .. 
P 2 5 . 
MnO. 
BaO.. 
SOs- 
C0 9 .. 
59. 78 
16.86 
3.08 
3.72 
.69 
2.96 
5. 39 
5.01 
1.58 
1 1 
75 
99.96 
w. 
65. 94 
12.95 
.33 
.07 
.05 
.10 
1.19 
2.32 
4.47 
trace 
trace 
12.47 
99. 89 
x. 
69. 67 
13. 72 
trace 
.07 
.34 
2.44 
4.73 
9.27 
100. 24 
76.22 
19.45 
trace 
trace 
trace 
trace 
3.82 
.11 
.13 
.29 
100. 02 
