IGNEOUS AND CRYSTALLINE ROCKS. 65 
SUNLIGHT INTRUSIVES. 
Descriptions supplied by Arnold Hague and T. A. Jaggar, jr. Analyses A, B, and 
C by W. F. Hillebrand, record No. 1801; D by H. N. Stokes, No. 1804. 
A. Quartz syenite, Copper Creek Basin. Laurvikose. Contains biotite, horn- 
blende, epidote, orthoclasc, augite, titanite, magnetite, and apatite. Hornblende 
very pale in color. 
B. Syenite porphyry, Sulphur Creek Basin. Lassenose. Contains oligoclase and 
biotite, in a groundmass of quartz and feldspar. 
C. Augite syenite porphyry, Copper Creek Basin. Laurvikose. Contains augite, 
biotite, orthoclase, a little hornblende, and quartz. 
D. Gabbro, southwest of Beams Hill, Sunlight Valley. Andose. Contains plagio- 
clase, pyroxene, magnetite, apatite, and a little biotite. 
55 39 80 
29 23 89 
16 21 44 
OL OF! Nees esis 
0 GED i [veeaveseor 
none | none none 
trace 07 07 
14 14 13 
27 27 21 
none | none none 
trace? | trace? |........ 
99. 84 | 100. 34 | 100. 10 99. 94 
ISHAWOOA INTRUSIVES. 
Descriptions supplied by Arnold Hague and T. A. Jaggar, jr. Analyses A and 
B by H. N. Stokes, record No. 1804; C and D by W. F. Hillebrand, No. 1765. 
A. Granite porphyry, base of Crater Mountain. Yellowstonose. Contains oligo- 
clase, orthoclase, biotite, and quartz. 
B. Diorite porphyry, Cabin Creek. Tonalose. Contains plagioclase, orthoclase, 
quartz, and abundant hornblende. This rock is intermediate between granite por- 
phyry and diorite porphyry, but nearer to the latter. 
C. Diorite, base of Needle Mountain. Yellowstonose. Contains plagioclase, 
quartz, biotite, with subordinate hornblende and orthoclase. Structure granitic. 
D. Diabase, entrance to Shoshone Canyon. Andose. Contains plagioclase, augite, 
and chlorite. 
