Silver Bell Mine, Mineral Mountain, Silver Bell District, Silver Bell Mts, Pima Co., Arizona, USA
|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 ListMineral list contains entries from the region specified including sub-localities
48 valid minerals.
GeochronologyMineralization 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 Time||Rocks, Minerals and Events|
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
|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
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. 
Localities in this Region
- Pima Co.
- Silver Bell Mts
- Silver Bell District
- Mineral Mountain
- Silver Bell District
- Silver Bell Mts
- Pima Co.
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.