246 
ANALYSES OF ROCKS, U. B. GEOLOGICAL SURVEY. 
[BULL. 168. 
2. SANDSTONE DIKES IN SHASTA COUNTY. 
Described by J. S. Diller in Bull. Geol. Soc. Amer., vol. 1, p. 411. 
The rock is made up of quartz, feldspar, and biotite, with a calcite 
cement. Serpentine, sphene, magnetite, and zircon also occur in it, 
but are less common. 
A. From Salt Creek, one half mile above McNett's. 
B. One and one-fourth miles below Ono Bridge, north fork of Cot- 
tonwood. 
C. D. Three-fourths of a mile below John Allen's, Dry Creek. 
E. From John Allen's, Dry Creek. 
Analyses A and B by T. M. Chatard, record No. 1106; C, D, and E 
by J. E. Whitfield, record Nos. 972, 973. 
Si0 2 . 
A1 2 3 
Fe 2 3 
FeO.. 
MgO . 
CaO . 
K 2 
H 2 Oatll0 o ... 
H 2 at red heat 
Ti0 2 ... 
PA -- 
MnO 
BaO 
C0 2 
S0 3 
CI 
48.13 
11.19 
1.25 
1.47 
2.22 
16.39 
2.29 
1.17 
.78 
1.78 
.24 
.14 
.29 
.04 
12.73 
100. 11 
48.10 
12.16 
1.02 
2.14 
1.65 
15.88 
2.46 
1.56 
.46 
3.27 
.47 
.13 
.26 
undet. 
10.36 
99.92 
59. 10 
14.02 
3.16 
1.42 
1.72 
9.35 
2.21 
1.49 
2.63 
.70 
trace 
trace 
4.65 
trace 
trace 
100. 45 
61.60 
12.15 
2.09 
3.30 
2.33 
6.92 
2.16 
1.41 
3.10 
trace 
.08 
trace 
5.05 
.27 
trace 
100. 46 
54.55 
10.64 
1.59 
1.16 
1.29 
14.30 
2.60 
1.68 
1.60 
trace 
.10 
1.53 
9.05 
.10 
79 
100. 31 
