Porphyry copper deposit in Sonora, Mexico

Names and other identifiers

Alternate names Los Pilares, Nacozari
Tract name Western Sierra Madre Occidental and Laramide Central (003pCu3007x)
Site status deposit

Geographic location

Country Mexico
State or province Sonora
Geographic location -109.629364652, 30.330446983
Geologic map unit -109.629364652, 30.330446983
Nearby data

Geologic information

Deposit type Porphyry copper
Age (Ma) 53Ma
Age determination method unknown
Age range 53 Ma
Age reference Singer and others (2008)
Minerals azurite/malachite, barite, chalcocite, chalcopyrite, chlorite, epidote, galena, goethite/limonite, hematite/specularite, jarosite, magnetite, muscovite/sericite, pyrite, scheelite, sphalerite, wolframite
Associated rocks andesite, andesite breccia, andesite tuff, latite
Tectonic setting continental margin
Stratigraphic age Eocene

Commodity and development information

Development status Past Producer
Tonnage (Mt) 147Mt
Cu grade (%) 1.04%
Contained copper 1,530,000t
Gold-Moly ratio -9999

Reference information

Comments Pilares was the first mine in the district. La Caridad Vieja is the faulted off acid sulfate top of the system. Rocks at Pilares: breccia, diabase dikes, dacite tuff, granodiorite, quartz monzonite, rhyolite tuff. Alteration: unknown.
Study area name Mexico
References Gilmour (1982); Leonard (1989); Long (1995); Thoms (1978); Palafox-Reyes and others (1998); Singer and others (2008)
Site reference Hammarstrom and others (2010)
Gilmour, Paul, 1982, Grades and tonnages of porphyry copper deposits, in Titley, S.R., ed., Advances in geology of the porphyry copper deposits, southwestern North America: Tucson, University of Arizona Press, p. 7–35.
Leonard, K.R., 1989, Preliminary deposit-type map of northwestern Mexico: U.S. Geological Survey Open-File Report 89-158, 350 p. (Also available at http://pubs.er.usgs.gov/publication/ofr89158.)
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.
Palafox-Reyes, J.J., Minjarez-Sosa, Ismael, Saavedra-Monreal, Rogelio, Alamazán-Vázquez, Emelio, Morales-Montaño, Mariano, Ochoa-Landin-L.H., Rodríguez-Torres, Rafael, Rivera-Enriquez, Braulio, Castro-Escarrega, J.J., and Zamora-Tovar, R.E., 1998, Carta geológico-minera, Nacozari H12-6, Sonora [Mexico]: Pachuca, Hidalgo, Servicio Geológico Mexicano, 1 sheet, scale 1:250,000.
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/.
Thoms, J.A., 1978, Textural variations and mineral zoning of the Pilares breccia pipe, Nacozari mining district, Sonora, Mexico, in Jenney, J.P., and Hauck, H.R., eds., Proceedings of the porphyry copper symposium: Tucson, Arizona Geological Society Digest 11, p. 143.