80 
ANALYSES OF ROCKS, U. S. GEOLOGICAL SURVEY. 
[BULL. 168. 
P. Red granitic rock resembling D, but with more dark spots, found 
in contact with the purplish slate, N. Consists mainly of red feldspar, 
quartz, and chlorite. Analysis by J. E. Whitfield, record No. 519. 
Dried at 104°. P. R. C. 1014. 
Q. Groundmass of red mottled quartzite. Analysis by W. ¥. Hille- 
brand, record No. 499. P. R. C. 1022. 
R. Green mottlings from Q. Mostly quartz and sericite. Analysis 
by Hillebrand, record No. 498. 
S. Another sample of the green mottlings, selected with especial 
care. Analysis by L. G. Eakins, record No. 1058. 
T. Brilliantly red vitreous quartzite. Analysis by R. B. Riggs, 
record No. 574. Dried at 105°. P. R. C. 1008. 
p. 
Q. 
R. 
s. 
T. 
Si0 2 ... 
68.36 
13.76 
2.65 
2.75 
.68 
.70 
3.56 
4.48 
.98 
1.57 
.33 
76.57 
9.21 
1.67 
3.94 
1.51 
.73 
3.07 
1.02 
1.89 
.42 
trace 
none 
.05 
trace? 
none 
trace 
77.70 
7.67 
3.55 
3.29 
1.83 
.26 
1.96 
1.04 
a 2. 36 
.30 
none 
83.27 
7.81 
1.99 
1.81 
1.59 
.20 
.19 
1.11 
2.32 
trace 
trace 
83.69 
7.50 
1.81 
.38 
.35 
.39 
2. 46 
2.61 
.72 
trace? 
A1 2 3 
Fe 2 3 
FeO 
MgO 
CaO 
Na 2 
K 2 
H 2 
Ti0 2 
P 2 5 
Zr0 2 
MnO 
SrO 
BaO 
trace 
undet. 
undet. 
none 
.66 
.04 
(?) 
none 
trace 
trace 
undet, 
undet, 
Li 2 
so 3 
100. 48 
100. 08 
100. 00 
100. 29 
99.91 
a Determined by difference. 
