150 
ANALYSES OF ROCKS, TT. S. GEOLOGICAL SURVEY. 
[no. 228. 
O. White syenite of the Shonkin Sag laccolith. Partial analysis. 
P. Shonkinite, Shonkin Sag laccolith. Contains augite, olivine, 
biotite, and orthoclase. 
Rocks O, P, described by Weed and Pirsson in Amer. Journ. Sci., 
4th series, vol. 12, p. 1. Analyses by W. F. Hillebrand, record No. 
1885. 
Si0 2 ...... 
A1 2 3 
Fe 2 3 
FeO.... 
MgO 
CaO 
Na 2 
K 2 
H 2 Oatl05°... 
H 2 above 105 c 
Ti0 2 
Zr0 9 
Cr 2 3 
V 2 3 
MnO 
NiO. 
SrO. 
BaO. 
C0 2 . 
s ... 
CI... 
F ... 

50. 00 
« 19. 36 
3.87 
2.67 
2.18 
4.96 
3.63 
8.52 
.46 
&3.53 
99.18 
47.88 
12.10 
3.53 
4.80 
8.64 
9.35 
2.94 
5.61 
.70 
1.52 
.77 
.03 
1.11 
.035 
.04 
.15 
trace 
.13 
.46 
.12 
.025 
trace 
.05 
99.99 
Includes Ti0 2 and P 2 5 . 
b Loss on ignition. 
The following rock and separations, from Square Butte, at the east 
end of the Highwood Mountains, are described by Lindgren in Amer. 
Journ. Sci., 3d series, vol. 45, p. 286. Analyses by W. H. Melville, 
record No. 1268. 
A. Post-Cretaceous sodalite-syenite. Pulaskose. Contains ortho- 
clase, some albite, hornblende, sodalite, analcite, and apatite. Ortho- 
clase predominates. The sodalite amounts to 8 per cent. P. R. C. 
184 and 201. 
B. Hornblende separated from A. Near barkevikite. 
