Metcalf Mines (Arizona Copper Co. group; Metcalf Open pit), Clifton, Greenlee County, Arizona, USAi

Regional Level Types
Metcalf Mines (Arizona Copper Co. group; Metcalf Open pit)	Group of Mines
Clifton	Town
Greenlee County	County
Arizona	State
USA	Country

A former surface and underground Cu-Ag-Au-Mo-Zn mine located in the center SE¼ sec. 4 and the SW¼ sec. 3, T4S, R29E (Clifton 15 minute topo map), located on the east side of the confluence of Chase Creek and King Gulch, at the old town site of Metcalf, about 6 miles from Clifton and 2.5 miles NW of Morenci, on private land. Discovered by Robert and James Metcalf in 1870. The principal claim is the Little Annie.
Produced 1882-1979. Past owners and operators included the Metcalf Brothers; Leszynsky Brothers; and the Arizona Copper Co. Ltd. (1882-1922). Owned and operated by the Phelps Dodge Corp., Morenci Branch, since 1922.

Mineralization is an irregular ore body. Associated rock units are the Morenci Granite Porphyry and the Precambrian granite-granodiorite complex. Ores occur as irregular bodies in porphyry, as replacement deposits of narrower porphyry dikes, as distinct NE-trending fisure veins, and as contact breccia between granite porphyry and quartz monzonite porphyry. Ore concentration involved extensive leaching (leached capping ranges in thickness from 200 to 1000 feet. Supergene enrichment of chalcocite; ores have generally been deposited by replacement in the porphyry mass. Alteration is surface oxidation to depths of 30 feet and sericitization of granite porphyry. Chalcotrichite occurs as a product of surface oxidation; chalcanthite occurs as efflorescences.

Metcalf Mines comprise 3 separate ore bodies: (ore body on Metcalf Ridge consists of supergene ore in granite porphyry; on King Ridge, porphyry and Precambrian granite are cut by NE-striking veins and breccias; underground mine on King Ridge opens a breccia pipe located along the contact of granite porphyry and quartz monzonite porphyry). Mining operations have caused blending of ores from these separate ore bodies. High grade ore zones are aligned along a N-S strike but most veins and dikes generally strike N40E.

The NW-striking Shannon Fault marks the NE edge of the ore body which was downthrown about 500 feet to the SW. Leached capping dips to the SW and vaguely parallels the topography. Native copper is found in open cuts as large irregular masses intergrown with cuprite. Cuprite also occurs as irregular veinlets in sericitized porphyry. The King breccia pipe has a N-S elliptical shape and is cut by steeply-dipping, N-S-trending fissure veins.

Area structures include irregular bodies of chalcocite ore contained in soft and sericitic granite porphyry near contact with sedimentary rocks. The porphyry contains inclusions of shale and metamorphosed limestone. General NW-striking step faults with normal displacements to the south.

Tectonic component is the Shannon Mountain Fault Block.

Workings included a small open pit on Metcalf Ridge; a large open pit on King Ridge; and an underground mine on the SE flank of King Ridge (referred to as the King breccia pipe). Surface workings and several shafts were developed on Metcalf Ridge and King Ridge, overlooking the confluence of King Gulch and Chase Creek. Primarily open cast mining and tunnelling on 4 levels; an incline connecting surface cuts with the Coronado Trail; the second level at about 70 feet below the surface opens the main body of porphyry. The Metcalf property was mined by underground and surface cut operations until 1920. The property remained idle until the Phelps Dodge Corporation developed the open pit and underground operations on the old workings in 1969.

The open pit mine has produced from 1975 to the present. Production data for the years 1975 through 1979 listed under the Metcalf open pit. Production data prior to 1921 is included in Longfellow Metcalf Mine data. Longfellow Metcalf also includes the other Arizona Copper Co. mines of Detroit, Longfellow, Humboldt, Coronado, Joy, Mammoth and Yavapai Mines.

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Link to USGS MRDS:	10048292

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References