OLARKE.l 
IGNEOUS AND CRYSTALLINE ROCKS. 
185 
10. MISCELLANEOUS ROCKS. 
A. Rhyolite, east bank of Arkansas River, Nathrop. Liparose. 
Described by Cross in Proc. Colorado Sci. Soc, vol. 2, p. 69. Con- 
tains quartz and sanidine in a groundmass mainly of quartz and alkali 
feldspar. This rock carries topaz and spessartite in its lithophysae. 
Analysis made by L. G. Eakins in the Denver laboratory. Sp. gr., 
2.602, 29°. P. R. C. 598. 
B. Granite, Platte Canyon. Alashose. Described by E. B. Mathews 
in Bull. 150, p. 172. Contains microcline, quartz, biotite, oligoclase, 
and fluorite. Apatite, zircon, magnetite, hematite, limonite, epidote, 
and rutile (?) are sometimes present. Analysis b}^ H. N. Stokes, record 
No. 1314. 
C. Horn blende-porphy rite, Hermano Peak, Sierra El Late. Las- 
venose. Described by Cross in 14th Ann., p. 165. Contains plagio- 
clase, hornblende, rare quartz, and a little biotite. Analysis by W. F. 
Hillebrand, record No. 1129. 
D. Hornblende-porphyrite, Lite Peak, Sierra El Late. Tonalose. 
Described by Cross in 14th Ann., p. 165. Contains plagioclase, horn- 
blende, and very little augite, in a groundmass of quartz, orthoclase, 
and plagioclase. Analysis by Hillebrand, No. 1129. 
E. Porphyrinic augite-diorite, Lone Cone, San Miguel Mountains. 
Tonalose. Described by Cross in 14th Ann., p. 165. Contains plagio- 
clase, augite, hornblende, and biotite, in a groundmass of quartz, 
orthoclase, and plagioclase. Inclusions of magnetite and apatite in 
the augite. Analysis by Hillebrand, No. 1429. 
A. 
B. 
c. 
i). 
E. 
Ii0 2 : 
69.89 
17. 94 
.39 
.52 
.14 
trace 
4.21 
4.38 
| 2.07 
77.02 
11.03 
.32 
1.09 
.14 
1.24 
2.85 
5.21 
} .3, 
62. 65 
16. 68 
2. 35 
2. 63 
1 . 43 
4.96 
4. 45 
2.75 
.27 
. 66 
.42 
.28 
.16 
.11 
.13 
trace 
59. 42 
10.79 
3. 23 
3.29 
2.24 
5. 57 
4.15 
2.82 
.27 
.79 
.68 
.35 
.13 
.07 
.14 
trace 
.44 
59. 19 
A1 2 0, 
1 8. 00 
Fe 2 0, 
3. 07 
FeO 
2 32 
MgO 
1.41 
CaO 
6. 55 
Na 2 
4.01 
K 2 
2.74 
H 2 at 100° 
.46 
H 2 above 100° 
1.06 
Ti0 2 
.58 
p 2 o 5 
trace 
.23 
trace 
.29 
MnO 
.19 
SrO 
.13 
BaO 
.18 
Li 2 
trace 
trace 
C0 2 
99. 77 
99. 85 
99. i»3 
100. 38 
100. 18 
