CLARKE.] 
IGNEOUS AND CRYSTALLINE ROCKS. 
199 
8. ELDORADO COUNTY. 
A. Granitite, Placerville canal, one-third mile north of Ditch Camp 
No. 7. Collected by W. Lindgren, who reports it as containing biotite, 
orthoclase, plagioclase, and quartz. Analysis by George Steiger, 
record No. 1591. 
B. Granodiorite, 2 miles south of Silver Lake Hotel. Collected by 
Lindgren, who reports it as containing hornblende, biotite, plagioclase, 
and quartz. Analysis by Steiger, No. 1591. Analyses A and B are 
published by Lindgren in Amer. Journ. Sci., 4th ser., vol. 3, p. 306. 
C. Porphyrite, 1 mile southwest of Latrobe. Published by Turner 
in 17th Ann., Part I, p. 521. Contains abundant plagioclase, less 
augite, calcite or dolomite, iron disulphide, a little chlorite, and sec- 
ondary greenish mica. Analysis by W. F. Hillebrand, record No. 
1432. P. R. C. 721. 
A. 
B. 
c. 
Si0 2 
77.68 
11.81 
.72 
.51 
.18 
.72 
2.96 
5.00 
.04 
.27 
.14 
.10 
trace 
67.45 
15. 51 
1.76 
2.21 
1.10 
3.60 
3.47 
3.66 
.14 
.63 
.58 
.12 
68.58 
13.04 
.26 
3.40 
1.01 
3.22 
4.94 
1.90 
.16 
1.00 
.57 
.20 
.15 
trace 
.10 
1.31 
.15 
A1 2 3 
Fe 2 3 
FeO 
MgO 
CaO 
Na 2 
K 2 
H 2 at 100° 
H 2 above 100° 
Ti0 2 
P 2 5 
MnO 
SrO 
BaO 
co 2 
FeS 2 . 
100. 13 
100. 23 
99.99 
