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U.S. Department of Energy
Office of Scientific and Technical Information

Hydrothermal adularia at Bodie, Mono County, California

Technical Report ·
OSTI ID:6250495
Adularia occurs in gold- and silver-bearing quartz veins and in hydrothermally altered dacite host rocks of late Miocene age at the Bodie mining district, Mono County, California. Chemical analyses of vein adularia indicate a composition of 95 percent KAlSi/sub 3/O/sub 8/. Optical, physical, and x-ray crystallographic properties of the adularia are consistent with those of high sanidine. The adularia formed between 8.6 and 7.1 m.y. ago, late in the history of the Bodie Hills volcanic field, during a period of intense potassium-silicate hydrothermal alteration and gold-silver mineralization. Chemical and isotopic analyses of adularia and associated vein minerals, quartz and calcite, and delta /sup 18/O and delta D measurements of fluid inclusions in these minerals indicate that a K- and Rb-rich solution of meteoric origin was the agent of alteration. Temperature (approximately 250/sup 0/C), K/Rb ratio, and delta /sup 18/O of the solution probably remained constant during potassium metasomatism and precipitation of the adularia.
Research Organization:
California State Dept. of Conservation, San Francisco (USA). Div. of Oil and Gas
OSTI ID:
6250495
Report Number(s):
USGS-OFR-78-942; ON: DE83902126
Country of Publication:
United States
Language:
English