128 
ANALYSES OF ROCKS, U. S. GEOLOGICAL SURVEY. [bull. 16 
M. Minette, intrusive sheet, head of Sheep Creek. Chiefly biotite 
augite, and orthoclase, with accessory apatite, plagioclase, quartz, an< 
iron ore, and some secondary calcite, chlorite, and kaolin. Analysi I 
by Hillebrand. 
N. Monzonite, Yogo Peak. Described in Amer. Journ. Sci., 3c 
series, vol. 50, p. 473, and 4th series, vol. 1, p. 356. Contains apatite 
sphene, iron ore, pyroxene, hornblende, biotite, orthoclase, and oligo 
clase, and a little secondary kaolin. Analysis by Hillebrand. 
O. Monchiquite, dike on Big Baldy Mountain. Contains much 
pyroxene, a few serpentinized olivines, iron ore, and apatite in a color- 
less base of analcite. Analysis by Hillebrand. 
P. Monchiquite, dike on Bandbox Mountain. Contains olivine, 
augite, biotite, analcite, and apatite, with traces of serpentine and 
chlorite. Analysis by Stokes. 
Q. Shonkinite, Yogo Peak. Described in Amer. Journ. Sci., 3d 
series, vol. 50, p. 474. Chiefly augite and orthoclase, with a consider- 
able amount of accessory biotite, iron ore, and andesine, less apatite 
and olivine, and a trace of kaolin. Analysis by Hillebrand. 
SiO, 
Fe 2 3 
FeO 
MgO 
CaO 
Na 2 
K 2 
H 2 OatllO°... 
H 2 above 110 c 
Ti0 2 
PA 
Cr 2 3 
NiO 
MnO 
SrO 
BaO 
Li 2 
S0 3 
CI 
co 2 
F 
M. 
52.26 
13.96 
2.76 
4.45 
8.21 
7.06 
2.80 
3.87 
1.53 
1.34 
.58 
.52 
trace 
.14 
.05 
.23 
trace 
.49 
100. 25 
N. 
54.42 
14.28 
3.32 
4.13 
6.12 
7.72 
3.44 
4.22 
.22 
.38 
.80 
.59 
trace 
.10 
.13 
.32 
trace 
100. 19 
o. 
48. 35 
13.27 
4.38 
3.23 
8.36 
9.94 
3.35 
3.01 
.90 
2.89 
.52 
.40 
trace 
.04 
.19 
.09 
.54 
trace 
.30 
.25 
100. 01 
P. 
48.39 
11.64 
4.09 
3.57 
12.55 
7.64 
4.14 
3.24 
.28 
2.56 
.73 
.45 
.07 
trace 
.15 
.32 
trace 
.08 
trace 
99.90 
48.98 
12.29 
2.88 
5.77 
9.19 
9.65 
2.22 
4.96 
.26 
.56 
1.44 
.98 
trace 
.08 
.08 
.43 
trace 
22 
99.99 
