122 ANALYSES OF ROCKS AND MINERALS, 1880-1908. 
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75 
Cr2O3 and SO; absent. 
6. MISCELLANEOUS ROCKS. 
A. Rhyolite, Thomas Range. Toscanose. Analysis made by L. G. Eakins in the 
Denver laboratory. Described by Cross in Proc. Colorado Sci. Soc., vol. 2, p. 69. 
Contains phenocrysts of quartz and sanidine in a groundmass mainly made up of quartz 
and alkali feldspar. 
B. Rhyolitic glass or pitchstone, edge of Gold Mountain mining district, 8 miles 
north of west from Marysvale. Liparose. Identified by Whitman Cross. Sp. gr., 
2.25 at 23.5°. Analysis by W. F. Hillebrand, record No. 1833. 
NEW MEXICO. 
1. BASALTS FROM RIO GRANDE CANYON. 
Described by Iddings, Bull. 66; also in Am. Jour. Sci., 3d ser., vol. 36, p. 220. 
Contain plagioclase, augite, olivine, and magnetite. A, B, and C contain quartz also; 
D is quartzless. Analyses by L. G. Eakins, record Nos. 847, 850. All andose. 
A. Light gray, dense. P. R. C. 548. 
B. Greenish black, dense. 
C. Dark red, vesicular. P. R. C. 549. 
D. Gray, dense. P. R. C. 547. 
