Grand Pacific Mine (Grand Pacific Copper Company property; Grand Pacific claims; Pacific group; Pacific Mine; Climax; Sandal group), Pacific Canyon, Apache Leap, Superior, Pioneer District, Pinal Mts, Pinal Co., Arizona, USA

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A group of 35 Cu-Ag-Au-Mn claims, and former underground mine, located in sec. 12, T2S, R12E, which lie mostly south of the Consolidated Holding & Trust Co.'s group (Daggs group), about 0.4 miles below Apache Leap in Pacific Canyon, about 2¾ miles south of Superior, at an altitude of about 3,650 feet (lower tunnel). Also located 10 miles east of the Echo Cliffs monocline. Discovered in 1885 by John Sandal and ceased production 1967. Claims extend into sec. 24. Operated by Mr. Juan Ortega (1955). Owned by Mr Fredricks Smith (1951). Other previous owners/operators include the Grand Pacific Copper Co.; Grand Pacific Mining Co.

The ore-bearing fissure or shear zone cuts massive gray limestone of the Grapevine Gulch formation Escabrosa and Martin Limestones). The limestone strikes north and dips 20º to 40ºE. The material of the shear zone on the lower tunnel level consists of brecciated limestone, clay gouge, iron and manganese oxides, and in places a coarse-grained brown calcite. The zone is about 10 feet wide on this level. The manganese and iron oxides are intimately mixed, and no crystalline oxides are noted. Mineralization includes secondary copper minerals. The orebody is tabular shaped, strikes N50E, dips 70SW, is 3.05 meters thick, and 30.48 meters long. Oxidation of Cu sulphides was strong. An associated rock unit is diabase. WNW joints controlled the main portion of mineralization. Local features include the NW-trending Iron Cap Fault, and the NE-trending Sandal Fault. Regional NW-trending fault systems, NE-trending fault systems. Although there are no intrusives at the surface here, mineralization is associated with Cretaceous-Paleozoic intrusive and faulting episodes.

Workings include 4 shafts with the deepest at 60 feet (1881). Workings also include at least 3 interconnecting tunnels in a course about N75E. The main workings are on the Sandal Fault.

References

The Resources of Arizona - A Manual of reliable Information Concerning the Territory, compiled by Patrick Hamilton (1881), Scottsdale, AZ: 60.

Jones, E.L., Jr. & F.L. Ransome (1920), Deposits of manganese ore in Arizona, USGS Bull. 710-D: 165.

Arizona Mining Journal (1922), July, 1922: 35.

Read, C.B. (1943), Copper deposits of the White Mesa Mining District, Coconino Co., Arizona.

Short, M.N., Galbraith, F.W., Harshman, E.N., Kuhn, T.H., and Wilson, E.D. (1943) Geology and Ore Deposits of the Superior Mining area, Arizona. Arizona Bureau of Mines Bulletin 151: 158.

Mayo, E.B. (1955), Metaliferous minerals and mineral fuels; Mineral resources, Navajo-Hopi Indian Reservations, Arizona-Utah, Vol. 1: 19-32

Farnham, L.L., Stewart, L.A., and Delong, C.W. (1961), Manganese deposits of eastern Arizona, US Bureau of Mines Information Circular 7990: 124, 126, 141.

Niemuth, N.J. & K.A. Phillips (1992), Copper Oxide Resources, Arizona Department of Mines & Mineral Resources Open File Report 92-10: 14 (Table 1).

U.S. Bureau of Mines file data.

Arizona Department of Mineral Resources Magmatic Copper Mines file, map.

Arizona Department of Mineral Resources Magma Copper Co. Miscellaneous #1 file.

Arizona Department of Mineral Resources U files.

MRDS database Dep. ID #10048317, MRDS ID #M899887; and Dep. ID #10283301, MAS ID #0040210485.

Mineral List

Bornite Calcite

Chalcocite Chrysocolla

Cuprite Limonite

Malachite Pyrite

8 entries listed. 7 valid minerals.