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drawings from thin sections, A

*
Plate XXIII / A. Relations of pyrite and siderite in Tonopah andesite. Drawings from thin sections.

Rhomb of cloudy siderite (s) associated with contemporary pyrite (p); earlier andesite, Fraction workings. Incident light. Magnified 11 diameters.

ex Josiah Edward Spurr (1870-1950 *). Geology of the Tonopah Mining District, Nevada. U. S. Geological Survey, Professional Paper No. 42 / Series A. Economic Geology, 56; B. Descriptive Geology, 66. (1905)

earlier adrifts, smaller.
 

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tags: J. E. Spurr; adrifts; economic geology; rhombs; rounds; Tonopah