Shea Mine (Shea property), Verde Mining District, Black Hills (Black Hill Range), Yavapai County, Arizona, USAi

Regional Level Types
Shea Mine (Shea property)	Mine
Verde Mining District	Mining District
Black Hills (Black Hill Range)	Group of Hills
Yavapai County	County
Arizona	State
USA	Country

A former underground Ag-Cu-Au-As-Pb-Baryte mine located on 16 patented and 3 unpatented claims, just south of the Copper Chief Mine. Originally owned by the Shea Copper Co.; then, the Phelps Dodge Corp. Produced 1918-1941.

It is located on the north side of an east-striking vein that dips south at an average of 42º; at surface the dip is steeper.

Mineralization is a Precambrian deposit. A vein contained in dark green, very dense and massive diorite rock. Northward-trending dikes of granodiorite porphyry cut the Shea basalt and are, in turn, cut by the Shea vein. The dikes are of medium-grained, pinkish granite, the feldspars of which are almost wholly sericitized near the vein. The vein strikes east and dips 30º to 50ºS., with a maximum width of 5 to 6 feet. The ore structure is rudely banded where the sulfides are mosts abundant. Quartz contains bands of siderite and ankerite with narrower streaks of sulfides.

The Shea basalt is greatly altered near the Shea vein, and chlorite, sericite, epidote, quartz, and carbonate minerals are common.

The vein minerals were deposited in a normal fault that has a probable throw of about 100 feet. The vein crops out for about 1,200 feet east of the portal of the main adit; its total length is more than 3,400 feet. The surface exposure ends less than 200 feet west of the main shaft where the low-dipping Copper Chief fault cuts the Shea vein. Both the most western and the eastern parts of the vein contain lenticular and discontinuous vein quartz. Throughout the mine the vein quartz does not average more than a foot in width, although in the oreshoot, the vein exceeds 5 feet.

A large part of the vein consists of coarsely crystalline quartz containing scattered pyrite and a few bunches of coarse ankerite or siderite and pyrite with some chalcopyrite. Locally some arsenopyrite and tetrahedrite are present.

Area features include foliation in Shea Basalt that trends N65E to N80E. The vein trends E-W and crosscuts foliation in the Precambrian rocks.

Workings include an incline on the dip of the vein for 1,220 feet on the incline or 825 feet vertically, or some 600 feet to the tunnel level and 200 feet deeper beyond. Workings on the tunnel level were some 3,000 feet and the total for the mine aggregates to about 7,000 feet of development (Reber, 1938, p. 58).

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References