120 ANALYSES OF ROCKS AND MINERALS, 1880-1908. 
3. THE BINGHAM DISTRICT. 
Porphyries collected by J. M. Boutwell, and described in P. P. 38, p.178. Analyses 
by E. T. Allen, record No. 1985. 
A. From Tribune tunnel, Telegraph mine. Monzonose. 
B, C, D. From British tunnel, Last Chance mine. B, SR. 1 of dacase. C. harzose. 
D, monzonose. 
According to Boutwell, A is the characteristic Bingham porphyry, and is inter- 
mediate between diorite porphyry and monzonite. It contains chiefly augite, biotite, 
and plagioclase, with a few grains of pyrite. B,C, and D are altered forms of this rock. 
A. B. Cc. D. 
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4. ROCKS FROM THE LA SAL MOUNTAINS. 
Petrographic descriptions by L. M. Prindle. Analyses by W. F. Hillebrand, 
record No. 2032. 
A. Monzonite porphyry, 2 miles west of Mount Peale. Akerose. Contains pheno- 
crysts of plagioclase, partly resorbed hornblende, and pyroxene in a groundmass of 
partly striated feldspar. It may contain also orthoclase and quartz. P. R. ©. 1306. 
B. Hgirite granite porphyry, about 1.5 miles south of Mount Waas. Omeose- 
liparose. Contains quartz, feldspar, pyroxene, and iron ore. The pyroxene is prob- 
ably for the most part egirite. P. R. C. 1304. 
C. Syenite-aplite porphyry resembling grorudite. About 2 miles south of Mount 
Waas. Liparose. Contains potash and soda-lime feldspars, quartz, pyroxene, titanite, 
and iron ore. In the groundmass are needles which are probably egirite. P. R. C. 
1301. 
D. Syenite porphyry resembling sdlvsbergite. About 1 mile northwest of Mount 
Waas. Philegrose near nordmarkose. Contains potash and soda-lime feldspars, quartz, 
pyroxene, and iron ore. Needles of eegirite (?) in the groundmass. P. R. C. 1303. 
E. Pulaskite, 1 mile west of Mount Waas. Nordmarkose. Contains potash feldspar, 
pyroxene, biotite, apatite, titanite, and iron ore. P. R. C. 1305. 
F. Noselite syenite porphyry, dike on northwest shoulder of Mount Waas. Miaskose. 
Contains feldspar, pyroxene, sodalite or noselite, apatite, titanite, and iron ore. The 
pyroxene appears to be mostly egirine-augite and the feldspar mainly potash feldspar. 
P.R. C. 1302. 
