CLARKE.] 
IGNEOUS AND CRYSTALLINE ROCKS. 
139 
M. Diorite, head of Rock Creek. Shosho?iose. Contains biotite, 
labradorite, and augite, in a groundmass of plagioclase, orthoclase, 
and quartz, with accessory magnetite, apatite, and hornblende. 
N. Diorite, main stock, Big Timber Creek. Andose. Contains 
biotite, augite, labradorite, quartz, orthoclase, apatite, and magnetite. 
O. Olivine-gabbro, Big Timber Creek. IV. %\ 1\ 2. Contains 
labradorite (?), brown hornblende, augite, olivine, and magnetite. 
P. Rock from Musselshell River, north of Crazy Mountains. 
■Monchiquose. Received from J. S. Diller, but undescribed. Re- 
garded by W. H. Weed as monchiquite. Analysis by L. G. Eakins, 
record No. 1021. 
Q. Hornstone, metamorphosed shale, contact zone, Sweet Grass 
Creek. An aggregate of augite, quartz, triclinic feldspar, and biotite. 
M. 
N. 
0. 
p. 
Q. 
Si0 2 
57. 97 
15. 65 
.73 
2.80 
4.96 
10. 93 
3. 03 
3. 16 . 
. 22 
.38 
.60 
.15 
50. 73 
19.99 
3.20 
4.66 
3.48 
8. 55 
4.03 
1.89 
.11 
.66 
1.59 
.81 
40. 42 
9. 98 
9.83 
10.67 
11.56 
10.78 
1.26 
.60 
.45 
1.17 
2.51 
.63 
.02 
25 
.02 
.05 
trace 
44.66 
12.12 
5.81 
3.20 
8.77 
8.14 
4.47 
2.75 
1 4.33 
1.02 
2.02 
57. 31 
A1 2 0, 
14.24 
Fe 2 :i 
FeO 
1.00 
3.24 
MgO 
4.60 
CaO 
11. 31 
Na 2 
2.64 
K 2 
4.55 
H 2 at 110° 
.25 
H 2 above 110° 
.24 
Ti0 2 
.52 
P 2 5 
.18 
(CoNi)O 
MnO 
trace 
.02 
.09 
trace 
.05 
.11 
.27 
trace 
.21 
2.19 
.08 
SrO 
trace? 
BaO 
.19 
Li 2 
trace? 
C0 2 
.17 
CI 
trace 
trace 
F 
100.69 
100. 13 
100. 20 
99.69 
100. 52 
