82 ANALYSES OF ROCKS AND MINERALS, 1880-1908. 
O. Olivine gabbro, Big Timber Creek. JV. 2?. 17. 2. Contains labradorite (?), 
brown hornblende, augite, olivine, and magnetite. P. R. C. 1734. 
P. Rock from Musselshell River, north of Crazy Mountains. Monchiquose. Re- 
ceived from J. S. Diller, but undescribed. Regarded by W. H. Weed as monchiquite. 
Analysis by L. G. Eakins, record No. 1021. 
Q. Hornstone, metamorphosed shale, contact zone, Sweet Grass Creek. An aggre- 
gate of augite, quartz, triclinic feldspar, and biotite. P. R. C. 1735. 
M N. oO. P. Q. 
: 50.73 | 40.42 | 44.66 57.31 
: 19. 99 9.98 | 12.12 14.24 
F 3. 20 9. 83 5. 81 1.00 
3 4.66 | 10.67 3. 20 3.24 
. 3.48 | 11.56 8.77 4.60 
, 8.55 | 10.78 8.14 11.31 
f 4.03 1.26 4.47 2. 64 
TE aeielememye ee ahs mies TL} 3.16] 1:89] l60} 275) 435 
HO at 110°........2... ere sss ses ies 5 222 -ll - 45 \ 4,33 =25 
H20 above 110°......... asin shag Seyi - 38 - 66 1.17 a 24 
TN Os eave icewesasds shoe = = siege e : 
R. Eleolite syenite, Peaked Butte, northeast side of the mountains. Umptekose. 
Described by Wolff and Tarr, loc. cit. Contains anorthoclase, augite, occasionally 
sodalite, egirine, apatite, magnetite, and some interstitial nephelite. Analysis by 
W. H. Melville, record No. 1291. P. R. C. 1736. 
Ra. Anorthoclase from R. Analysis by W. F. Hillebrand, record No. 1297. 
S. Tinguaite, var. sdlvsbergite, intrusive sheet north of Shields River. P. R. C. 
1737. 
T. Tinguaite, var. sdlvsbergite, dike north part of mountains. Nordmarkose. 
P. R. C. 1738. 
U. Tinguaite, var. sdlvsbergite, dike at head of Sixteenmile Creek. Nordmarkose. 
P.R. C. 1739. 
S, T, and U are the rocks described by Wolff and Tarr in their paper upon “‘ Acmite 
Trachyte.’? Mineral composition the same as under R. Analyses by W. H. Melville, 
record No. 1291. 
