Esperanza-Sierrita

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

Names and other identifiers

GMRAP ID 89
Tract name Western Sierra Madre Occidental and Laramide Central (003pCu3007x)
Site status deposit

Geographic location

Country United States
State or province Arizona
Geographic location -111.134582473, 31.870466718
Geologic map unit -111.134582473, 31.870466718
Nearby data

Geologic information

Deposit type Porphyry copper
Deposit subtype Cu-Mo
Age (Ma) 55Ma
Age determination method unknown
Age range 57–53 Ma
Age reference Singer and others (2008)
Minerals anhydrite/gypsum, apatite, azurite/malachite, biotite, bornite, brochantite, chalcocite, chalcopyrite, chlorite, chrysocolla, copper, covellite, cuprite/tenorite, enargite, epidote, ferrimolybdite, fluorite, galena, goethite/limonite, hematite/specularite, jarosite, kaolinite, magnetite, marcasite, molybdenite, montmorillonite, pyrite, pyrrhotite, rutile, sericite, sphalerite, tetrahedrite, zeolite
Associated rocks breccia, dacite porphyry, quartz latite porphyry, quartz monzonite porphyry, conglomerate, granite, andesite, andesite porphyry, granodiorite, quartz diorite, quartz monzonite, quartzite, rhyolite, rhyolitic welded tuff
Tectonic setting continental margin
Stratigraphic age Paleocene–Eocene

Commodity and development information

Development status Producer
Major commodities Cu
Tonnage (Mt) 2,262Mt
Cu grade (%) 0.294%
Mo grade (%) 0.0292%
Au grade (g/t) 0.003g/t
Ag grade (g/t) 1.2g/t
Contained copper 6,650,000t
Gold-Moly ratio 0.1

Reference information

Comments Combined production 1262.4 Mt of Esperanza (1959–1984) and Sierrita (1970–2004); combined resource 999.6 Mt in 2004. Exposed.
Study area name United States
References Bouse and others (1999); Cook and Robinson (1991); Linch (1966); Long (1995); McCandless and Ruiz (1993); Titley (1982); West and Aiken (1982); Singer and others (2008)
Site reference U.S. Geological Survey National Mineral Resource Assessment Team (2002)
Bouse, R.M., Ruiz, Joaquin, Titley, S.R., Tosdal, R.M., and Wooden, J.L., 1999, Lead isotope compositions of Late Cretaceous and early Tertiary igneous rocks and sulfide minerals in Arizona—Implications for the sources of plutons and metals in porphyry copper deposits: Economic Geology, v. 94, p. 211–244. (Also available at http://dx.doi.org/10.2113/gsecongeo.94.2.211.)
Cook, A., and Robinson, R.F., 1991, Sierrita porphyry copper deposit, Pima county, Arizona, in Hollister, V.F., ed., Case histories of mineral discoveries: Littleton, Colo., Society for Mining, Metallurgy, and Exploration, Inc., v. 3, p. 41–43.
Linch, D.W., 1966, The economic geology of the Esperanza mine and vicinity, in Titley, S.R., and Hicks, C.L., eds., Geology of the porphyry copper deposits, southwestern North America: Tucson, University of Arizona Press, p. 267–279.
Long, K.R., 1995, Production and reserves of Cordilleran (Alaska to Chile) porphyry copper deposits, in Pierce, F.W., and Bolm, J.G., eds., Porphyry copper deposits of the American Cordillera: Tucson, Arizona Geological Society Digest 20, p. 35–68.
McCandless, T.E., and Ruiz, J., 1993, Rhenium-osmium evidence for regional mineralization in southwestern North America: Science, v. 261, p. 1282–1286. (Also available at http://www.mccgeoscience.com/public_html/PDFs/mccandless%20ruiz%201993.pdf.)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.
West, R.J., and Aiken, D.M., 1982, Geology of the Sierrita-Esperanza deposit, Pima mining district, Pima County, Arizona, in Titley, S.R., ed., Advances in geology of the porphyry copper deposits, southwestern North America: Tucson, University of Arizona Press, p. 433–465.