140 
ANALYSES OF ROCKS, U. S. GEOLOGICAL SURVEY. 
[bull. 168, 
COLORADO. 
1. DENVER BASIN. 
Rocks described by Cross in Mon. XXVII. Analyses A, B, D, and 
E by L. G. Eakins, C by W. F. Hillebrand. All but A were made 
in the Denver laboratory. 
A. Dolerite, dike near Valmont. Contains augite, plagioclase, oli- 
vine, orthoclase, and biotite, with accessory magnetite and apatite. 
Record No. 1145. P. R. C. 534. 
B. Augite separated from A. P. R. C. 105. 
C. Basalt, Table Mountain, lower capping sheet. Contains plagio- 
clase, orthoclase, augite, magnetite, and apatite, with olivine much 
serpentinized. Sp.gr. 2.83, 22.5°. 
D. Basalt, earlier flow, south slope of North Table Mountain. Con- 
tains augite, olivine, plagioclase, probably orthoclase, magnetite, apa- 
tite, and a little biotite. P. R. C. 535. 
ID. Augite-mica-syenite, from north fork of Turkey Creek, -Jefferson 
County. Contains orthoclase, augite, biotite, rhombic pyroxene, horn- 
blende, plagioclase, quartz, apatite, and magnetite. Sp. gr. 2.857, 
29.5°. P. R. C. 532. 
Si0 2 . 
A1A 
Fe 2 3 
FeO. 
MgO 
CaO. 
Na. 2 
K 2 0. 
H 2 0. 
Ti0 2 
P 2 5 
MnO 
BaO. 
CI... 
S0 3 . 
48.25 
16. 73 
3.99 
6.28 
5.77 
8.32 
3.24 
4.08 
1.72 
.89 
.68 
trace 
.01 
.08 
.12 
100. 16 
B. 
49.10 
7.95 
8.30 
12.37 
22.54 
trace 
trace 
100. 26 
C 
52.59 
17.91 
3.81 
5.18 
4.11 
7.24 
2.94 
3.83 
1.24 
.84 
.14 
trace 
05 
99.88 
]). 
49.69 
18.06 
2.64 
6.19 
5.73 
8.24 
2.99 
3.90 
.91 
.85 
.81 
.13 
.13 
100. 27 
56.90 
18.50 
.17 
4.61 
5.10 
6.17 
2.99 
4.14 
.51 
.19 
.79 
trace 
trace 
ioo. o; 
