CLARKE.] 
IGNEOUS AND CRYSTALLINE ROCKS. 
197 
7. PLACER COUNTY. 
First, a series of rocks from the Ophir mining district, described by 
Lindgren in 14th Ann., p. 249. Analyses by W. F. Hillebrand, record 
Nos. 1119, 1133, 1134. 
A. Granodiorite, quarries at Lincoln, 8 miles west of Ophir. Con- 
tains feldspars, quartz, biotite, and horn blende. 
B. Pyritiferous amphibolite, Conrad tunnel. Partly altered. Con- 
tains p3 r rite, hornblende, magnetite, feldspars, quartz, epidote, chlorite, 
a few scales of mica, rutile, and carbonates. Sp. gr. 2.901, 23°. 
C. Dike rock, near camptonite, Casey's tunnel, Flat Ledge, Dun- 
can Hill. Contains hornblende, feldspars, pyrite, and apatite, with 
secondary epidote and quartz. 
D. Altered wall rock, Mina Rica vein. Sp. gr. 2.979, 20°. 
E. Altered wall rock, Plantz vein. These rocks, D and E, contain 
quartz, muscovite, a little chlorite, pyrite, and sphene, with carbonates 
of calcium, magnesium, and iron. 
A. 
B 
c. 
D. 
E. 
Si0 2 
65.54 
16.52 
1.40 
2.49 
2.52 
4.88 
4.09 
1.95 
.12 
.59 
.39 
.18 
.06 
45.56 
14. 15 
1.20 
9.83 
6.76 
2.30 
1.57 
1.18 
.23 
4.84 
1.11 
.14 
.25 
traces 
trace 
trace 
trace 
.03 
3.04 
7.86 
.10 
60. 09 
16. 43 
2.28 
3.01 
4.37 
5.76 
4.52 
.70 
.20 
1.16 
.63 
.12 
.12 
37.01 
12.99 
.43 
3.57 
5. 49 
9.78 
.13 
4.02 
.13 
1.92 
.85 
.06 
.24 
traces 
trace 
trace 
trace 
.04 
15.04 
7.99 
46. 13 
15.82 
.89 
2. 27 
2.13 
10.68 
.17 
5. 30 
.12 
2. 42 
.<>: 
.10 
.09 
traces 
trace 
trace 
trace 
.04 
11.24 
1.61 
A1 2 3 
Fe 2 3 
FeO 
MgO 
CaO 
Na 2 
K 2 
H 2 Oatl00° 
H 2 above 100° 
Ti0 2 
P 2 0, 
MnO 
Ni, Zn 
SrO 
trace 
trace 
trace 
trace 
trace 
none 
trace 
.07 
.34 
BaO 
Li 2 
so 3 
co 2 
FeS 2 
CuoS (?) 
100. 73 
100. 15 
99.80 
99.69 
99.68 
