78 ANALYSES OF ROCKS AND MINERALS, 1880-1908. 
H. Altered Butte granite. Decomposed near quartz-pyrite veins. Shows opaline 
silica, with sericite derived from feldspar. Hornblende gone; mica recognizable only 
as sericite masses having the form of biotite. 
Analyses G and H by Stokes, record Nos. 1792, 1787. 
I. Altered Butte granite, 300-foot level, Colusa mine. Derived from A. Contains 
quartz, altered orthoclase and plagioclase, and sericite. 
J. Altered Butte granite, wall rock, 1,300-foot level, Parrot mine. Derived from 
A. Contains quartz, sericite, pyrite, bornite, etc. 
K. Altered Butte granite, enargite vein, 1,000-foot level, Leonard mine. Contains 
quartz, kaolin, pyrite, etc. 
L. Altered Butte granite, veinlets in Original mine. Contains quartz, sericite, 
partly altered feldspars, calcite, zinc blende, etc. 
Analyses I, J, by E. T. Allen, record No. 1964; K, L, by W. F. Hillebrand, record 
No. 1971. 
1.82 3.06 8. 52 1.89 
19 1.21 -42 | trace 2.13 
18 35 - 20 05 7.36 
21 50 37 08 16 
NO). 2/8 arsaysinie a SB SORES RIESE ES VawceeacnGeas kee 5 5. 30 4.78 4.34 - 03 4. 41 
sO At 110" ccc necatnaumseasea re eccdendine eeanee sesamin 87 1,41 2.88 1.20 - 87 2.19 
ee above 75 5.25 7. 68 3.01 3. 88 4.09 
ft Ty] 159 73 ‘60| 51 "68 -61 
99. 68 | 100.01 | 100.15 | 102.00 
IGESS’ Obscene nie es eee OS os see iainingead adie aes an Reiia es siete emuees - 06 2.05 
Soreeteys eee 100. 09 | 99. 95 
M. Bluebird granite, Nettie mine. Alaskose. An aplite. Contains orthoclase 
and quartz, with a little plagioclase and a sprinkling of biotite. Analysis by H. N. 
Stokes, record No. 1686. ~ 
N. Same rock and locality as M. Analysis by W. F. Hillebrand, record No. 1692. 
O. Pitchstone, or rhyolite-dacite obsidian, Butte. Lassenose. Phenocrysts of 
andesine, quartz, and orthoclase in a glassy base. 
P. Rhyolite, Hyde Park dike. Tehamose. Contains sanidine, quartz, plagio- 
clase, and biotite in a groundmass of quartz and feldspar. Analyses O, P, by Stokes, 
record No. 1686. 
Q. Quartz porphyry, Modoc mine. Toscanose. Contains quartz, orthoclase, and 
plagioclase in a groundmass of quartz and feldspar. A few small biotites are present. 
Feldspar partly altered to sericite. Analysis by Hillebrand, record No. 1692.’ 
R. Altered rhyolite porphyry, 1,800-foot level, Anaconda mine. Contains quartz 
phenocrysts, with sericite, pyrite, etc. Analysis by Hillebrand, record No. 1971, 
partial only. 
