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Santa Cruz deposit (Casa Grande Santa Cruz deposit; Francisco Grande deposit; Fanny-Granny deposit; Franny-Granny deposit; Casa Grande; Casa Grande West), Casa Grande area, Casa Grande, Casa Grande District, Pinal Co., Arizona, USA

Santa Cruz deposit, Casa Grande area, Casa Grande, Casa Grande District, Pinal Co., Arizona, USA

Photo: DM06
Latitude: 32°53'25"N
Longitude: 111°52'35"W
A former underground Cu-Mo-Au-Ag deposit/prospect located in the center sec. 13 and sec. 24, T6S, R4E, and in sec. 19, T6S, R5E (Stanfield 7.5 minute topo map), about 7¼ miles W of Casa Grande proper (halfway between Casa Grande and Stanfield). Discovered 1976. Owned by the Casa Grande Copper Co.

Mineralization is a porphyry copper deposit. The ore zone is 2000 meters long, 800 meters wide, with a depth-to-top of 1600 meters and a thickness of 1700 meters. May be the largest atacamite deposit in the world. Ore control was intrusions and faulting.

The high grade of the ore body is due to a supergene enrichment zone composed of atacamite and chrysocolla in the oxide zone.

No production as yet, reserves proven for future open pit operations.


Greeley (1978) Arizona Department of Mineral Resources Special Report 2: 83-87.

Ullmer (1978) Journal of Geochemical Exploration: 9(2-3): 235-236.

Paydirt (1982) Casa Grande Copper Project on 'Back Shelf'. No. 522, Dec. 1982: 7.

Paydirt (1984) Getty Pays $10 Million for Land near Casa Grande Orebody: No. 541, July, 194: 21A-22A.

Cook, S.S. (1988b), Petrologic studies of the supergene copper mineralization at the Santa Cruz copper deposit, Pinal Co., Arizona (abstract), Geological Society of America Abstracts with Progs. 20: A336.

Mining Magazine (1988) In Situ Copper Mining Tests in U.S.A., December 1988: 460.

Ahlness and Millenacker (1989) Bureau of Mines Investigates i Situ Copper Mining Feb-Mar 1989: 9-15.

Dahl, Linda J. (1989) Summary Report - Casa Grande, American Mining Congress Journal, 2/89: 16.

Mining Journal, London (1989) Draft Mine Design, September 29, 1989.

The Mining Record (1990) ASARCO Takes Legal Action in Mining Research Venture, March 1990: 3.

Mining Engineering (1991) In Situ Copper Mining at Santa Cruz. A Project pdate, August 1991: 1031-1034.

Niemuth, N.J. & K.A. Phillips (1992), Copper Oxide Resources, AZ Dept. Mines & Min. Resources Open File Rept. 92-10: 15 (Table 1).

Paydirt (1992) Santa Cruz In Situ Copper Leacng Research ooking Good, february 1992: 3B (38 ?).

Sawyer, M.B., Gurmendi, A.C., Daley, M.R., and Howell, S.B. (1992) Principal Deposits of Strategic and Critical Minerals in Arizona, U.S. Bureau of Mines Special Publication, 334 pp.

American Mining Manual (1994) Copper Project gets green Light: 7.

Skillings Mining Review (1994) Arizona In Situ Miing Research Project Proceeds, November 26, 1994: 15.

Anthony, J.W., et al (1995), Mineralogy of Arizona, 3rd.ed.: 121.

Southwestern Paydirt (1995) Industry-Government Project has Big Potential, February, 1995: 4A-9A.

Mining Record (1996) Pilot-Scale Test Begins at Santa Cruz In Situ Project: 107(8), February 21, 1996: 4.

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.

MRDS database Dep. ID #10097042, MRDS ID #M030493; and Dep. ID #10113316, MAS ID #0040211072; and Dep. ID #10234953, MRDS ID #TC35431, MAS ID #0040210076.

Mineral List

var: Sericite


10 entries listed. 8 valid minerals.

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