IGNEOUS AND CRYSTALLINE ROCKS. 139 
F. Rhyolite, 1} miles northeast of Clipper Mills, on tramway to Rock Creek, Shasta 
County. Tehamose. A spherulitic rock containing a few microscopic particles of 
feldspar and hornblende. Analysis by Hillebrand, No. 678. P. R. (, 1424. 
G. Rhyolite tuff, divide between the west fork of Willards Creek and the stage road, 
in Lassen County. Elevation, 5,800 feet. Composed almost wholly of fine angular 
particles of clear glass. Analysis by George Steiger, record No. 1427. P. R. (. 1425. 
Materials for A to F dried at 110° previous to analysis. 
2. DACITES AND ANDESITES. 
A. Gray dacite, Lassen Peak. Lassenose. Contains hornblende, biotite, plagio- 
clase, quartz, scarce pyroxene, magnetite, apatite, and a glassy base. Analysis by 
T. M. Chatard, record No. 111. P. R.C. 82. 
B. Secretion in dacite, Lassen Peak. Composed chiefly of plagioclase and horn- 
blende. Analysis by Chatard, No. 110. P. R. C. 1426. 
C. Reddish dacite, Lassen Peak. Essentially like A. Analysis by Chatard, No. 
110. P.R. OC. 1427. 
D. Dacite, near the timber line, west base of Lassen Peak. Lassenose. Small 
phenocrysts of plagioclase and hornblende, with a few of quartz, in a reddish-gray 
groundmass containing much amorphous matter. Analysis by W. F. Hillebrand, 
record No. 668.,. P. R. C. 1428. 
E. Secretion in D. Hessose. Composed essentially of plagioclase and hornblende. 
Analysis by Hillebrand, No. 669. P. R. C. 1429. 
Rocks A, (, D, and E described by Diller in Bull. 150, p. 217. 
100.19 | 99.88 | 100.27 | 100. ow 100. 07 
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