IGNEOUS AND CRYSTALLINE ROCKS. 109 
E. Pink orthoclase crystals from D. Analysis by Hillebrand. 
F. Hornblendic porphyrite, lower Buckskin Gulch. Andose. Contains plagioclase, 
orthoclase, quartz, hornblende, biotite, magnetite, apatite, and zircon, with a little 
secondary calciteand chlorite. Sp. gr. 2.768,16° Analysis by Hillebrand. P.R.C. 
89 and 506. 
G. Biotite porphyrite, dike in gneiss in the North Mosquito amphitheater. Tonalose. 
Composition like F, but with no hornblende, much biotite, and some pyrite. Sp. gr., 
2.740, 16°. Analysis by Hillebrand. P.R. . 507. 
100.11 | 99.16 | 100.73 | 100.61 
H. Rhyolite (nevadite), from Chalk Mountain. Liparose. Mainly quartz and 
feldspar, the latter being sanidine and plagioclase. A little biotite, magnetite, apatite, 
and zircon are present. Analysis by Hillebrand. P.R. C. 64, 512, and 1289. 
I. Sanidine from H. Analysis by Hillebrand. P.R.C 64. 
6. TENMILE DISTRICT. 
Rocks described by Cross in 14th Ann., p.165. Analyses madein the Denver labo- 
ratory—A and C by W. F. Hillebrand, B by L. G. Eakins. 
A. Quartz-hornblende-mica porphyrite, Gold Hill. Yellowstonose. Contains 
plagioclase, hornblende, biotite, and quartz in a groundmass of quartz, orthoclase, and 
alittle plagioclase. P.R.C. 510. 
B. Quartz porphyrite, Sugar Loaf. Toscanose. Contains plagioclase, biotite, and 
quartz, in a groundmass of quartz and orthoclase. P. R. (. 509. 
C. Quartz porphyrite, Chicago Mountain. Lassenose. Contains plagioclase, ortho- 
clase, biotite, and quartz. P.R.(. 508. 
