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Sulphur Bank, California, a major hot-spring quicksilver deposit

Donald E. White and C. E. Roberson
Sulphur Bank, California, a major hot-spring quicksilver deposit (in Petrologic studies--A volume in honor of A. F. Buddington)
Geological Society of America, Boulder, CO, United States (1962) 397-428


Sulphur Bank is the most productive mineral deposit in the world that is clearly related to hot springs. The ore is late Quaternary and is localized in rocks immediately below the water table that existed prior to mining. The hydrothermal alteration and the mineralogy of the veins have been controlled largely by the water table. The upper part of an andesite flow has been above the water table and is extensively altered by sulfuric acid formed by oxidation of H (sub 2) S. Characteristic alteration minerals are opal, cristobalite, and anatase where leaching has been intense, and kaolinite, halloysite, alunite, soluble sulfates, and perhaps jarosite and montmorillonite where acid attack has been less intense. Native S without cinnabar was abundant near the surface, but, as the water table was approached, S decreased, and cinnabar became abundant. The principal ore bodies were at and below the water table and consisted of cinnabar, marcasite, pyrite, dolomite, calcite, quartz, a zeolite mineral, and all the minerals of the original rocks. Metacinnabar and stibnite were locally common. The waters deep in the spring system appear to be nearly neutral, but near the water table they become slightly acid because of mixing with downward-percolating waters containing H (sub 2) SO (sub 4) resulting from oxidation of H (sub 2) S. Films of condensate in the areas of most intense acid leaching may have pH values of 1 or less. The present thermal waters are very high in total CO (sub 2) , B, ammonia, Na, and I and are low in silica and K as compared to many thermal and mineral waters. Chemically and isotopically they are unlike most thermal waters associated with recent volcanism. The present rate of discharge of water of deep origin is calculated to be about 50 gpm. The average concentration of quicksilver in the ore solutions was probably 0.05-8 ppm, assuming an interval of deposition between 10,000 and 100,000 years and a rate of discharge of water of 50-1000 gpm. The most reasonable estimate is believed to be 0.1-1 ppm. Present temperatures are relatively low compared to other hot-spring systems of clearly volcanic origin. The present heat flow is on the order of 200,000 cal/sec, or about 12 times "normal" for the area; total heat flow in the past may have been as much as 20 times as much. The heat is almost certainly volcanic in origin, but, despite association with Quaternary volcanic rocks and volcanic heat, the chemical and isotopic compositions of the water and gases now being discharged indicate that these fluids are nonvolcanic in origin.

Title: Sulphur Bank, California, a major hot-spring quicksilver deposit
Title: Petrologic studies--A volume in honor of A. F. Buddington
Pages: 397-428
Published: 1962
Text Language: English
Publisher: Geological Society of America, Boulder, CO, United States
Accession Number: 1962-012382
Categories: Economic geology, general
Bibliographic Level: Analytic
Illustration Description: illus., tables
N32°30'00" - N42°00'00", W124°30'00" - W114°15'00"
Source Note: New York, Geol. Soc. America
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Bibliography and Index of North American Geology, U. S. Geological Survey, Reston, VA, United States
Update Code: 1962
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