CLARKE.] 
IGNEOUS AND CRYSTALLINE ROCKS. 
187 
3. PLUMAS COUNTY. 
Other rocks from this county are described under the heading of the 
Lassen Peak area. The following rocks, with two exceptions, were 
collected by H. W. Turner, who supplies the descriptions: 
A. Granite, dike in serpentine, south slope of Grizzly Hill. De- 
scribed by Turner in Amer. Geologist, vol. 17, p. 375. Contains 
quart/, albite, and muscovite. Analysis by H. N. Stokes, record No. 
1562. P. R. C. 757. 
B. Meta-rhyolite, near Tower Rock, Grizzly Mountains. Described 
1>\ Turner in 14th Ann., p. 441. Contains porphyritic quartz, feld- 
spar, and pyrite, in a hue groundmass. Analysis by W. F. Hille- 
brand, record No. 1273. P. R. C. 741. 
C. Meta-rhyolite, near Greenville. Collected by Diller, who finds 
phenocrysts of quartz in a groundmass chiefly of quartz and feldspar. 
Analysis by Hillebrand, record No. 1458. 
D. Granodiorite, southwest base of Mount Ingalls. Description 
supplied by Turner. Contains plagioclase, quartz, orthoclase, brown 
mica, green hornblende, iron oxide, and a little apatite, sphene, and 
epidote. Analysis by Hillebrand, record No. 1456. P. R. C. 727. 
E. Granodiorite, Spanish Peak. Description supplied by Turner. 
Contains plagioclase, quartz, orthoclase, biotite, hornblende, iron ore, 
ind apatite; also abundant secondary epidote and chlorite. Analysis 
by Stokes, record No. 1562. P. R. C. 756. 
A. 
B. 
c. 
D. 
E. 
Si0 2 
76.00 
14.88 
.65 
.10 
.06 
.19 
3.52 
2.77 
.20 
1.42 
.04 
.11 
trace 
73.25 
13.25 
72. 77 
13.00 
1.28 
2.65 
.67 
2.47 
4.95 
.34 
.07 
1.16 
.22 
.04 
.08 
trace 
trace 
trace 
.47 
67.33 
15.93 
1.90 
1.59 
1.63 
4.09 
3.76 
2.46 
.19 
.66 
.36 
.11 
.09 
trace 
.08 
trace 
59.68 
17.09 
2.85 
2.75 
3.54 
6.62 
3.87 
1.31 
.15- 
1.00 
.65 
.25 
trace 
trace 
.04 
trace 
.20 
trace 
.03 
A1 2 3 
Fe 2 3 
FeO 
1.74 
.28 
2.23 
2.69 
3.79 
.07 
1.03 
trace 
trace 
trace 
trace? 
trace 
trace 
1.05 
MgO 
CaO 
Na 2 
K 2 
H 2 Oatl00° 
H 2 above 100° 
Ti0 2 
P 2 5 
MnO 
SrO . . . 
BaO 
Li 2 
trace 
C0 2 
so 3 
trace 
trace 
trace 
CI 
F . 
FeS-.. 
.58 
~~99T94~ 
"Too. is 
99.96 
100.17 
100.03 
