IGNEOUS AND CKYSTALLINE ROCKS. 
103 
K. Lamprophyre, allied to camptonite, Black Face, Telluride 
quadrangle. Consists of a fine felt of plagioclase, augite, and brown 
Rornblende microlites, with flakes of biotite, and a cryptocrystalline 
part, which is probably in large degree orthoclasc. Sonic magnetite and 
apatite. Analysis by Hillebrand, record No. 1710. Sp. gr. 2.783, 22°. 
L. Quartz monzonite, northeast of San Miguel Peak, Telluride quad- 
rangle. Contains orthoclase and plagioclase in about equal amounts, 
with abundant quartz and much less' augite, hornblende, biotite, mag- 
netite, and apatite. Analysis by H. N. Stokes, record No. 1764. 
Sp. gr. 2.720, 34°. 
M. Gabbroitic facies of a diorite-monzonite stock, Ophir Needles, 
Telluride quadrangle. Contains abundant labradoritc, with augite, 
hypersthene, biotite, orthoclase, magnetite, apatite, and a very little 
; quartz. Analysis by Stokes, record No. 1764. Sp. gr. 2.860, 33°. 
N. Gabbro-porphyry, pass south of Mount Sneft'els, Telluride quad- 
rangle. Contains numerous phenocrysts of labradorite or bytownite, 
in a groundmass of plagioclase, orthoclase (?), augite, hypersthene, 
biotite, magnetite, and apatite. Analysis by Stokes, record No. 1764. 
Sp. gr. 2.949, 26.5°. 
J. 
K. 
L. 
M. 
N. 
Si0 2 
43.98 
13. 30 
3.67 
6.92 
• 
7. 03 
10.66 
2.15 
1.64 
.42 
1.52 
1.18 
.32 
.22 
.03 
.05 
.06 
trace 
6.46 
55.65 
17.04 
2.81 
5.17 
3.42 
6. 82 
3.27 
2.29 
.46 
1.49 
.90 
. 37 
.20 
none 
.05 
.08 
trace 
65.70 
15.31 
2.54 
1.62 
1.62 
2.56 
3.62 
4.62 
.17 
.42 
.72 
.33 
trace 
56. 93 
17. 03 
3.67 
4. 54 
3. 30 
6.51 
3.19 
2.58 
.13 
.45 
1.03 
.44 
.10 
47. 32 
16. 71 
6.92 
5.94 
5.69 
8.51 
2.70 - 
2.02 
.24 
1.04 
1.50 
.96 
.08 
A1 2 3 
Fe 2 3 
FeO 
MgO 
CaO 
Na 2 
K 2 
H 2 Oatll0° 
H 2 above 110° 
Ti0 2 
P 2 5 
MnO 
NiO, CoO 
SrO 
,03 
.12 
trace 
none 
.12 
.03 
.06 
.08 
none 
none 
none 
trace 
.06 
.07 
trace 
none 
.19 
trace 
BaO 
Li 2 
C0 2 
so 3 
none 
CI 
FeS 2 
.54 
100. 15 
100. 02 
99.53 
100.04 
99.95 
