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Silver Bell Mine, Mineral Mountain, Silver Bell District, Silver Bell Mts, Pima Co., Arizona, USA

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Latitude & Longitude (WGS84): 32° 24' North , 111° 30' West
Latitude & Longitude (decimal): 32.40000,-111.50000
Other regions containing this locality:Sonoran Desert, North America

A Cu-Ag-Mo-Au mine located in the NW ¼ sec. 4 & the center of sec. 11, T.12S., R.8E. (Vaca Hills 15 minute topo map). Discovered 1909. First produced 1954. Owned by the American Smelting & Refining Co. (ASARCO). This mine is the open pit continuance of the former El Tiro and Oxide underground mines.

Mineralization is supergene enriched deposits of chalcocite with minor copper carbonates and silicates derived from sheeted, closely spaced, veinlets and seams of quartz, pyrite, chalcopyrite, and minor molybdenite in hydrothermally altered Laramide dacite porphyry and monzonite.

Workings include two open pit operations since 1954. Up through 1972, production has been some 59,800,000 million tons of ore averaging about 0.8% Cu, 0.06 oz. Ag/T, 0.004% Mo, and minor Au & Pb.

Mineral List

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

48 valid minerals.


Mineralization age: Paleocene : 63.5 Ma to 62.9 Ma

Important note: This table is based only on rock and mineral ages recorded below and is not necessarily a complete representation of the geochronology, but does give an indication of possible mineralization events relevant to this locality. As more age information is added this table may expand in the future. A break in the table simply indicates a lack of data entered here, not necessarily a break in the geologic sequence. Grey background entries are from different, related, localities.

Geologic TimeRocks, Minerals and Events
ⓘ Molybdenite (youngest age)62.9 Ma
ⓘ Molybdenite (oldest age)63.5 Ma

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

Ypresian - Campanian
47.8 - 83.6 Ma
Early Tertiary to Late Cretaceous volcanic rocks

Age: Phanerozoic (47.8 - 83.6 Ma)

Stratigraphic Name: Williamson Canyon Volcanics

Description: Rhyolite to andesite and closely associated sedimentary and near-surface intrusive rocks; commonly dark gray to dark greenish gray or greenish brown. In the ranges west of Tucson, this unit includes thick welded ash-flow tuffs. Volcanic rocks of this unit are inferred to be derived from vents and volcanoes above magma chambers that solidified to form the granitic rocks of map unit TKg. These rocks are restricted to southeastern Arizona except for a small outcrop near Bagdad. (50-82 Ma)

Comments: Related, broadly, to unit TKg

Lithology: Major:{rhyolite,dacite,andesite}, Minor:{clastic}

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, used under Creative Commons Attribution 4.0 License

Localities in this Region


This page contains all mineral locality references listed on 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 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.


Engineering Mining Journal (1904), The Silverbell Camp, Arizona: 77: 639.

Stewart, C.A. (1912) The geology and ore deposits of the Silverbell mining district, Arizona, A.I.M.E. Bull. 65: 455-505 (A.I.M.E. Transactions, Vol. 43: 240-290.

Galbraith, F.W. (1947), Minerals of Arizona, Arizona Bureau of Mines Bull. 153: 9.

Kerr, P.F. (1951), Alteration features at Silverbell, Arizona, Geological Society of America Bull.: 62: 451-480.

Huttl, John B. (1954) Silver Bell ASARCO’s New Arizona Copper project starts production, Engineering & Mining Journal: 155(7): 72-79.

Richard, K.E. & J.H. Courtright (1954), Structure & Mineralization at Silver Bell, Arizona, Mining Engineering, Vol. 6(11): 1095-1099 (A.I.M.E. Transactions, 1954 - Vol. 199 (1955).

Mining World (1958) Silver Bell - ASARCO Makes a Mine at a Known Deposit: April, 1958: 40-45.

Galbraith, F.W. & D.J. Brennan (1959), Minerals of Arizona: 87.

Hardwick, W.R. (1963) Open-pit copper mining and concentrating methods and costs, Silver Bell unit, American Smelting and Refining Co., Pima County, Arizona: U.S. Bureau of Mines Information Circular I.C. 8153, 72 p.

Richard, K.E. & J.H. Courtright (1966), Structure & Mineralization at Silver Bell, Arizona, in Titley, S.R. and Hicks, C.L., eds., Geology of the porphyry copper deposits, southwestern North America: 157-163 (University of Arizona Press).

Watson, Barry N. (1968) Updating the Geology and Structural Ore Controls at Silver Bell, Arizona, presented at the Arizona A.I.M.E. Spring Meeting, Mining Geology Division, May 20, 1968, 11 pp.

Skillings, David N., Jr. (1970) ASARCO’s Silver Bell Unit, Skillings Mining Review, July 25, 1970: 3-5.

Keith, Stanton B. (1974), Arizona Bureau of Geology & Mineral Technology, Geological Survey Branch Bull. 189, Index of Mining Properties in Pima County, Arizona: 143 (Table 4).

Roe, A. (1980), Micromounting in Arizona, Mineralogical Record: 11: 261-265.

Graybeal, F.T. (1982) Geology of the El Tiro area, Silver Bell 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. 487-505.

Niemuth, N.J. & K.A. Phillips (1992), Copper Oxide Resources, Arizona Department of Mines & Mineral Resources Open File Report 92-10: 13 (Table 1).

Anthony, J.W., et al (1995), Mineralogy of Arizona, 3rd. ed.: 107, 118, 126, 128, 193, 213, 262, 276, 277, 286, 296.

Singer, D.A., Berger, V.I., and Moring, B.C. (2005): Porphyry Copper Deposits of the World: Database, Map, and Grade and Tonnage Models. USGS Open-File Report 05-1060.

Arizona Bureau of Mines file data.

MRDS database Dep. ID file #10161929, MRDS ID #D000333, MAS ID #0040190009.

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