150 ANALYSES OF ROCKS AND MINERALS, 1880-1908. 
| 100. 37 | 100. 40 | 100.28 | 100.79 99. 97 
L. Bleached country rock, next to vein, Osborne Hill mine. Derived from sand- 
stone. Analysis by George Steiger, record No. 1541. 
M. Altered wall rock, Empire mine. Derived from granodiorite. Analysis by 
Steiger, No. 1541. Sp. gr., 2.782, 20°. 
N. Altered wall rock, Ebaugh tunnel. Derived from granodiorite. Mainly quartz 
and sericite, with pyrite, apatite, sphene, and carbonates. Analysis by Steiger, No. 
1541. Sp. er., 2.747, 20°. 
O. Altered wall rock, Federal Loan mine. Derived from siliceous argillite. Anal- 
ysis by Steiger, No. 1541. 
SiO». 71.97 | 58.43 | 56.25 34.91 
Al2O: 15.75 | 17.40 | 17.65 15. 55 
Fe0. 17 <a 76 17 
FeO. 45 2.19 2.64 4.96 
MgO 80 1.50 1.69 4.58 
CaO. 80 5.25 4. 46 11.10 
INGO) osicvssa.acenteesinct carota mira tanarmcctessaisteoaisinss cietetece eabercaetalt - 33 1.76 - 30 19 
BO ras shane ap antinveene sete ciora tiorereeaeiunersa Serena z 4.§8 4,03 6.01 4.28 
FO: at 00 vrced a a sewed cera auepei neti ax casinos % . 30 30 . 80 30 
HG BHO VE i100 eam vemeincnrenemmarins arom nasa a | 22.16 2.61 2. 36 1.86 
1 OO ceca enteral eh cn hau en Ns cc ntl exe : 88 none 25 1.65 
7. PLACER COUNTY. 
First, a series of rocks from the Ophir mining district, described by Lindgren in 14th 
Ann., p. 249. Analyses by W. F. Hillebrand, record Nos. 1419, 1433, 1434. 
A. Granodiorite, quarries at Lincoln, 8 miles west of Ophir. Tonalose. Contains 
feldspars, quartz, biotite, and hornblende. P. R. C. 1526. 
B. Pyritiferous amphibolite, Conrad tunnel. Partly altered. Contains pyrite, 
hornblende, magnetite, feldspars, quartz, epidote, chlorite, a few scales of mica, rutile, 
and carbonates. Sp. gr., 2.901, 23° 
C. Dike rock, near camptonite, Casey’s tunnel, Flat Ledge, Duncan Hill. Placerose. 
Contains hornblende, feldspars, pyrite, and apatite, with secondary epidote and 
quartz. 
