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Twin Buttes

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Porphyry copper (Cu-Mo) deposit in Arizona, United States

Names and other identifiers

GMRAP ID 90
Tract name Western Sierra Madre Occidental and Laramide Central (003pCu3007x)
Site status deposit

Geographic location

Country United States
State or province Arizona
Geographic location -111.035277778, 31.892777778
Geologic map unit -111.035277778, 31.892777778
Nearby data
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Geologic information

Deposit type Porphyry copper
Deposit subtype Cu-Mo
Age (Ma) 58Ma
Age determination method unknown
Age range 58 Ma
Age reference Singer and others (2008)
Minerals actinolite, anhydrite/gypsum, apatite, apophyllite, azurite/malachite, biotite, bornite, brochantite, chalcocite/digenite, chalcopyrite, chlorite, chrysocolla, copper, cuprite/tenorite, Cu-Mn wad, diopside, epidote, ferrimolybdite, fluorite, galena, garnet, goethite/limonite, hematite/specularite, jarosite, magnetite, molybdenite, montmorillonite, powellite, pyrite, pyrolusite, pyrrhotite, rhodochrosite, rhodonite, rutile, scheelite, sericite, siderite, sphalerite, stibnite, tenorite, tetrahedrite, vanadinite, vesuvianite, wollastonite, wulfenite
Associated rocks breccia, quartz monzonite porphyry, quartz-feldspar porphyry, skarn, andesite, anhydrite, conglomerate, dolomite, fanglomerate, granite, limestone, quartzite, rhyodacite porphyry, rhyolite, sandstone, shale, siltstone, tuff
Tectonic setting continental margin
Stratigraphic age Paleocene

Commodity and development information

Development status Occurrence
Major commodities Cu
Tonnage (Mt) 940Mt
Cu grade (%) 0.502%
Mo grade (%) 0.023%
Au grade (g/t) 0.019g/t
Ag grade (g/t) 5.8g/t
Contained copper 4,700,000t
Gold-Moly ratio 0.82

Reference information

Comments 100% covered.
Study area name United States
References Berter (1978); Barter and Kelly (1982); Einaudi (1982); Kelly (1976); Titley (1982); Singer and others (2008)
Site reference U.S. Geological Survey National Mineral Resource Assessment Team (2002)
Barter, C. F., 1978, Stratigraphy, alteration, and ore controls in the main ore zone, Twin Buttes mine, Pima County, Arizona: Arizona Geological Society Digest 11, p. 115–116. (Also available at http://www.arizonageologicalsoc.org/Default.aspx?pageId=1665440 and at http://archives.arizonageologicalsoc.org/digests/AGS_DIG11_S.PDF.)
Barter, C.F., and Kelly, J.L., 1982, Geology of the Twin Buttes mineral deposit, in Titley, S.R., ed., Advances in geology of the porphyry copper deposits, southwestern North America: Tucson, University of Arizona Press, p. 407–432.
Einaudi, M.T., 1982, Description of skarns associated with porphyry copper plutons, southwestern North America, in Titley, S.R., ed., Advances in geology of the porphyry copper deposits, southwestern North America: Tucson, University of Arizona Press, p. 139–183.
Kelley, J.L., 1976, Geology of the Twin Buttes copper deposit, Pima county, Arizona: AIME Annual Meeting, Las Vegas, February 22–26, 1976, Preprint No. 76–1–3, 23 p.
Singer, D.A., Berger, V.I., and Moring, B.C., 2008, Porphyry copper deposits of the world—Database and grade and tonnage models, 2008: U.S. Geological Survey Open-File Report 2008-1155, [45] p. and digital data, accessed December 31, 2013, at http://pubs.usgs.gov/of/2008/1155/.
Titley, S.R., 1982, Some features of tectonic history and ore genesis in the Pima mining district, in Titley, S.R., ed., Advances in geology of the porphyry copper deposits, southwestern North America: Tucson, University of Arizona Press, p. 387–406.