PLATE IX. 
Photomicrographs of Rocks. 
A, Tracliydolerite (661 C. C.) from Isabella mine, level 10. Composed of orthoclase, plagioclase, analcite 
augite, olivine, and magnetite. Orthoclase and analcite are confined to the groundmass. Magnified 
28 diameters. 
B, Monchiquite (204 C. C.) from dump of Block 8 mine. Composed of analcite, augite, olivine, with a small 
amount of orthoclase. Analcite in phenocrvsts and orthoclase in the groundmass. Magnified 28 
diameters. 
C, Vogesite (569 C. C.) from Jennie Sample mine, level 5. Composed of orthoclase, analcite, hornblende, 
and biotite. Magnified 35 diameters. 
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