144 ANALYSES OF ROCKS AND MINERALS, 1880-1908. 
N. Basalt from the cone at south base of Burney Butte, Shasta County. Andose. 
Composed of plagioclase and augite, with some olivine and a globulitic base. Analysis 
by R. B. Riggs, record No. 685. P. R. C. 1451. : 
O. Basalt, near east end of rim of Crater Peak, Shasta County. Hessose. Contains 
plagioclase and pyroxene, some of the latter being hypersthene with a trace of olivine. 
Analysis by R. B. Riggs, record No. 682. P. R. C. 1452. 
P. Hornblende basalt, Kosk Creek near its mouth, by the great bend of Pit River, 
Shasta County. Auvergnose. Contains abundant phenocrysts of hornblende, with 
a few of plagioclase, pyroxene, and olivine, in a groundmass of plagioclase, augite, and 
magnetite. The hornblendes are deeply corroded, and some have disappeared, leav- 
ing groups of magnetite grains to mark their former presence. Analysis by L. G. 
Eakins, record No. 1022. Described by Diller in Am. Geologist, vol. 19, p. 253. P. 
R. C. 1453. 
Rocks dried at 105° to 110° before analysis, except in the case of the rock marked L. 
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. Near alaskose. De- 
scribed by Turner in Am. Geologist, vol. 17, p. 375. Contains quartz, albite, and 
muscovite. Analysis by H. N. Stokes, record No. 1562. P. R. C. 757. 
B. Metarhyolite, near Tower Rock, Grizzly Mountains. Toscanose. Described by 
Turner in 14th Ann., p. 441. Contains porphyritic quartz, feldspar, and pyrite, ina 
fine groundmass. Analysis by W. F. Hillebrand, record No. 1273. P. R. ©. 741. 
C. Dacite, near Greenville. Yukonose. Collected by Diller, who finds pheno- 
crysts of quartz in a groundmass chiefly of quartz and feldspar. Analysis by Hille- 
brand, record No. 1458. P. R. C. 1454. 
D. Granodiorite, southwest base of Mount Ingalls. Yellowstonose. Description 
supplied by Turner. Contains plagioclase, quartz, orthoclase, brown mica, green 
hornblende, iron oxide, and a little apatite, sphene, and epidote. Analysis by Hille- 
brand, record No. 1456. P. R. C. 727. 
E. Granodiorite, Spanish Peak. Tonalose. Description supplied by Turner. 
Contains plagioclase, quartz, orthoclase, biotite, hornblende, iron ore, and apatite; 
also abundant secondary epidote and chlorite. Analysis by Stokes, record No. 1562. 
P. R. C. 756. 
