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The Geysers, West Mayacmas District, Mayacmas Mts (Mayacamas Mts), Sonoma Co., California, USA

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Latitude & Longitude (WGS84): 38° 48' 6'' North , 122° 48' 11'' West
Latitude & Longitude (decimal): 38.80194,-122.80306
GeoHash:G#: 9qbstx9t9
Köppen climate type:Csb : Warm-summer Mediterranean climate

A geothermal/evaporite deposit located about 12 miles due E of Cloverdale.

The Geysers geothermal area consists of a series of steam vents along Geyser Creek Canyon where high sulfuric acid waters have deposited a variety of sulfate minerals. The area is now not active and minerals are not being formed.

Commodity List

This is a list of exploitable or exploited mineral commodities recorded from this region.

Mineral List

Mineral list contains entries from the region specified including sub-localities

34 valid minerals. 1 (TL) - type locality of valid minerals.

Rock Types Recorded

Note: this is a very new system on mindat.org and data is currently VERY limited. Please bear with us while we work towards adding this information!

Rock list contains entries from the region specified including sub-localities

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Alphabetical List Tree Diagram

Regional Geology

This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.

Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org

0 - 2.588 Ma

ID: 2596197
Landslide deposits

Age: Pleistocene (0 - 2.588 Ma)

Description: Poorly sorted clay, silt, sand, gravel, boulders, and rock masses. Only a few large landslides are shown. For a more complete map of landslide deposits, see Nilsen and others (1979)

Reference: Blake, M.C. Jr., R.W. Graymer, R.E. Stamski. Geologic Map and Map Database of Western Sonoma, Northernmost Marin, and Southernmost Mendocino Counties, California. U.S. Geological Survey Miscellaneous Field Studies Map MF-2402. [93]

Cretaceous - Jurassic
66 - 201.3 Ma

ID: 3190324
Mesozoic tectonic rocks

Age: Mesozoic (66 - 201.3 Ma)

Stratigraphic Name: Franciscan Complex

Comments: metamorphic protolith: mafic volcanics

Lithology: Shale

Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529. [154]

Cretaceous - Jurassic
66 - 201.3 Ma

ID: 2791046
Franciscan melange

Age: Mesozoic (66 - 201.3 Ma)

Stratigraphic Name: Franciscan Complex

Description: Melange of fragmented and sheared Franciscan complex rocks.

Comments: Coast Ranges. Includes areas of Franciscan rocks specifically distinguished as melange on the Geologic Map of California. Includes parts of central and eastern Franciscan belts of Blake et al. (1988)

Lithology: Major:{melange}

Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052. [133]

Data and map coding provided by Macrostrat.org, used under Creative Commons Attribution 4.0 License

Localities in this Region
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This page contains all mineral locality references listed on mindat.org. This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in mindat.org without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.


Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Goldsmith, E. (1877), On boussingaultite and other minerals from Sonoma County, California: Academy of Natural Sciences of Philadelphia Proceedings: 28: 264-266.
Hanks, Henry Garber (1884), Fourth report of the State Mineralogist: California Mining Bureau. Report 4, 410 pp. (includes catalog of minerals of California pp. 63-410), and miscellaneous observations on mineral products): 68.
Irelan, William, Jr. (1888b), Eighth annual report of the State Mineralogist [includes mineral resources of the State, with contributions by W.A. Goodyear, H.A. Whiting, and Stephen Bowers]: California Mining Bureau. Report 8, 946 pp.: 633.
Laizure, Clyde McK (1926), Sonoma County: California Journal of Mines and Geology, California Mining Bureau (Report 22): 22: 314-365.
Allen, Eugene T. & Arthur L. Day (1927), Steam wells and other thermal activity at “The Geysers,” California: Carnegie Institute Washington Publication 378; [(abstract) Geol. Zentralbl. (1928), Band 38: 176-177; Neues Jahrb., Referate 2: 634-636; Scottish Geog. Mag (1928): 44: 230-231]: 39, 40, 45.
Vonsen, Magnus (1941) Preliminary report on minerals of The Geysers of Sonoma County, California. Mineralogist: 9: 245-248.
Vonsen, Magnus (1946), Minerals at “The Geysers,” Sonoma County, California: California Division Mines Report 42: 287-293.
Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II. John Wiley and Sons, Inc., New York, 7th edition, revised and enlarged, 1124 pp.: 399, 476, 492.
Anonymous (1955), World news on mineral occurrences: Rocks & Minerals: 31: 462 (on metastibnite).
Smith, Robert Leland (1958), Some new occurrences of sassolite in the United States: American Mineralogist: 43: 1204-1205.
Steiner, A. (1958), Occurrence of wairakite at The Geysers, California: American Mineralogist: 43: 781.
Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 62, 63, 113, 179, 214, 258, 263, 282, 285, 288, 293, 327, 356, 382, 383.
White, D.E. (1967) Mercury and base-metal deposits with associated thermal and mineral waters. In: H.L. Barnes (Editor), Geochemistry of hydrothermal ore deposits. Holt Reinhart and Winston, New York: 590.
Dunning, Gail E. and J.F. Cooper (1969a) Letovicite from The Geysers, Sonoma County, California. California Division Mines and Geology Mineral Information Service: 22: 135.
American Mineralogist (1970): 55: 2103-2104.
Tschernich, R. (1975), Zeolites of the world, 1975.
Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 53, 239, 263, 264, 265, 356, 371, 410.
Economic Geology (1984): 79: 671-695.
American Mineralogist (1988): 73: 145-152.
Dunning, G. S. & Cooper, J. F. (1993): History and minerals of The Geysers Sonoma County, California. Mineralogical Record 24 (5): 339-352.

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