Cox Gulch prospects, Cox Gulch, Palmetto District, Patagonia Mts, Santa Cruz Co., Arizona, USA

‡Ref.: Schrader, F.C. & J.M. Hill (1915), Mineral deposits of the Santa Rita and Patagonia Mountains, Arizona, USGS Bull. 582: 291-292.

Simons (1971) Open File Map.

MRDS database Dep. ID file #10039569, MRDS ID #M050340.

A series of otherwise unnamed Cu prospects extending from the former Gray camp southeastward up Cox Gulch for nearly 2 miles, along the contact of the quartz monzonite intruded by granite porphyry, on private land.

Mineralization is a series of small veins in general of very similar character. The granite porphyry is impregnated with pyrite and chalcopyrite, and the quartz monzonite is silicified, altered, and impregnated with the same minerals for a short distance from the contact. The quartz monzonite is jointed along east-west and north-south lines. Along many of these joints, particularly those of the east-west system, there are ½ inch veins of pyrite, chalcopyrite, and a black, iridescent copper-bearing sulphide, either covellite or chalcocite. These veins are pseudo-banded, the banding being apparently due to alteration and replacement of the original constituents. The host rock unit is the Mt. Wrightson Volcanics.

In the granite porphyry at the head of the gulch there are several openings on shear zones or fault lines that strike NNE directions and dip to the west. The country rock is impregnated with pyrite and chalcopyrite, which are concentrated in the shear zones and faults. These deposits are in the main crudely banded, and the country rock is more siliceous along the veins. Some of the smaller veins are separated from the walls by a narrow band of drusy quartz which is usually frozen to the walls. In many places, beginning at about 6 feet below the surface, the pyrite and chalcopyrite are coated with films of chalcocite. Alum and copper sulphate commonly coat the tunnel walls in these workings.

These prospects have been opened by short tunnels and pits on small veins.