CLARKE.] 
IGNEOUS AND CRYSTALLINE ROCKS. 
149 
K. Dacite, Bald Mountain, near Rosita. Contains plagioclase, bio- 
tite, hornblende, sometimes augite, magnetite, and quartz. Sp. gr. 
2.574, 24°. Record No. 1068. P. R. C. 530. 
L. Mica-dacite. Contains plagioclase, sanidine, biotite, and quartz. 
Sp. gr. 2.563, 24°. Record No. 1068. 
M. Rhyolite, Pennsylvania Hill. Sp. gr. 2.470, 26°. Record No. 
1079. P. R. C. 525. 
N. Rhyolite, Round Mountain. Contains sanidine, quartz, some 
glass, and accessory garnet. P. R. C. 521. 
O. Rhyolite, Silver Cliff. Sp. gr. 2.560, 15°. Record No. 1125. 
P. R. C. 522. 
Si0 2 .. 
ALA- 
Fe 2 3 
FeO.. 
MgO. 
CaO.. 
Na 2 . 
Ti0 2 
PA 
MnO 
66.46 
17.91 
2.42 
.35 
.49 
2.89 
4. 79 
3.74 
1.01 
trace 
100. 06 
67.49 
17.76 
2.54 
.08 
.35 
1.67 
5.03 
4.40 
.52 
trace 
trace 
99.84 
M. 
70.87 
15.18 
2.18 
.12 
.60 
1.58 
3.47 
5.04 
1.08 
trace 
trace 
trace 
100. 12 
x. 
75. 20 
12.96 
.37 
.27 
.12 
.29 
2.02 
8.38 
.58 
trace 
.03 
100. 22 
75. 39 
13.65 
.38 
.18 
.15 
.51 
1.84 
6.81 
1.13 
trace 
trace 
.14 
100. 18 
