152 ANALYSES OF ROCKS AND MINERALS, 1880-1908. 
8 ELDORADO COUNTY. 
A. Granitite, Placerville canal, one-third mile north of Ditch Camp No. 7. Alas- 
kose. Collected by W. Lindgren, who reports it as containing biotite, orthoclase, 
plagioclase, and quartz. Analysis by George Steiger, record No. 1591. P. R. C. 1527. 
B. Granodiorite, 2 miles south of Silver Lake Hotel. Amiatose. 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 Am. 
Jour. Sci., 4th ser., vol. 3, p. 306. P. R. C. 1528. 
C. Porphyrite, 1 mile southwest of Latrobe. Dacose. Published by Turner in 
17th Ann., pt. 1, p. 521. Contains abundant plagioclase, less augite, calcite or dolo- 
mite, iron disulphide, a little chlorite, and secondary greenish mica. Analysis by W. 
F. Hillebrand, record No. 1432. P. R. C. 721. 
9, AMADOR COUNTY. 
Rocks collected by H. W. Turner, and analyses published in 14th Ann., p. 441, and 
17th Ann., pt. 1, p. 521. Additional data supplied by Turner. Analyses by W. F. 
Hillebrand, record Nos. 1432, 1456, and 1597. 
A. Rhyolite, south point of Buena Vista Peak. Magdeburgose. Contains sanidine, 
quartz, and biotite in a glassy groundmass. P. R. C. 729. 
B. Quartz monzonite, north fork of Mokelumne River. Amiatose. Contains plagio- 
clase, microcline, quartz, abundant biotite, iron ore, sphene, apatite, and perhaps 
tutile. P.R.C.770. 
C. Quartz monzonite, north fork of the Mokelumne River. Toscanose. Like B. 
P. R. C. 765. 
D. Quartz porphyrite schist, 24 miles southeast of Buena Vista Peak. Tehamose. 
Contains porphyritic quartz and hornblende, also calcite and other carbonates. See 
14th Ann. P. R. C. 723. 
E. Quartz diorite gneiss, north fork of Mokelumne River. Tonalose. Contains 
plagioclase, hornblende, quartz, brown mica, accessory biotite, and iron oxide. 
P.R. C. 764. 
F. Diorite porphyry, north fork of Mokelumne River. Andose. Contains plagio- 
clase, brown hornblende, epidote, and a little sulphide of iron and chlorite. P. R. 
C. 769. 
