‡Ref.: Schrader, F.C. & J.M. Hill (1915), Mineral deposits of the Santa Rita and Patagonia Mountains, Arizona, USGS Bull. 582: 222-226.
Galbraith, F.W. & D.J. Brennan (1959), Minerals of Arizona: 80.
Drewes, H.D. (1971) Geologic map of the Mount Wrightson quadrangle, southeast of Tucson, Santa Cruz and Pima Counties, Arizona: U.S. Geological Survey Miscellaneous Geologic Investigations Map I-614, 1 sheet, scale 1:48,000.
Keith, Stanton B. (1975), Arizona Bureau of Mines Bull. 191, Index of Mining Properties in Santa Cruz County Arizona: 89 (Table 4).
Anthony, J.W., et al (1995), Mineralogy of Arizona, 3rd.ed.: 426.
U.S. Bureau of Mines file data, Gringo Mine group.
Arizona Bureau of Mines file data.
MRDS database Dep. ID file #10037110, MRDS ID #M030418; and, Dep. ID #10259124, MAS ID #0040230209.
A former small underground Au-Ag-Pb-Cu-Zn-Mo-Feldspar mine located on 9 claims, in the NE¼NE¼NW¼ sec. 36, T.21S., R.15E., in the southern part of the district about 3 miles NNW of Patagonia in Gringo Gulch (south side), a northeast tributary of Temporal Gulch, ½ mile of Fresno Springs, at an elevation of about 4,250 feet, on National Forest land. It is about ¼ mile above the mouth of Gringo Gulch. It was discovered about 1893 by R.R. Richardson. Operated 1907-1937. Owned at times, or in part, by the Arizona Gold Mines & Milling Co. (1906-1907); Altamirano; and, M. Richmond.
Mineralization is in E-W-trending irregular lensing quartz-calcite fissure veins cutting rhyolitic tuff and andesitic flows. Two main veins and several mineralizaed cross veins exist. The ore zone is 6.1 meters wide and dips 80S. Ore concentration was hydrothermal mineralization of gold-bearing siliceous solutions through fissures after intrusion or erupting of igneous rocks.
The country rock is andesite (Middle Member of the Bathtub Formation; the Gringo Gulch Volcanics, and dacite-porphyry. The andesite is a more or less propylitically altered, epidotized gray, fine-grained, moderately porphyritic rock. It is somewhat banded with flow structure and weathers reddish-brown. Calcite films coat the joint planes and some calcite occurs in the rock. The rock is composed principally of long and short laths of oligoclase-andesine, hornblende, and biotite resting in a glassy base having parallel fluidal structure, with a few larger feldspar phenocrysts some of which are nearly 0.2 inches long. There is also considerable magnetite and a little augite and calcite. The rock is apparently correlative with the early andesite occurring elsewhere.
The andesite is cut by a steeply southward-dipping sheeting, about parallel with the lode, and also by two other sheeting structures, one trending northeast and the other northwest.
The deposits are contained mainly in two veins, the Gringo and the Independent, which traverse the andesite and are said to extend for several miles. This mine extends for some 4,500 feet on the veins. The veins range in width from 5-20 feet. The Gringo vein is accompanied in places on the footwall by a 7 foot dike which carries almost the same amount of gold as the vein and seems to be a metasomatic replacement deposit in wall rock. The Independent vein is about parallel to, and 600 feet N of the Gringo vein, and widens to 40 feet where joined by spur veins. The property extends 4500 feet on vein.
There are also several diagonal or cross veins on the property, one of which extends from the Independent vein near the east end of the ground to the Gringo vein beyond the shaft, near the west end.
The veins of the Gringo Mine and vicinity belong to the late metallogenetic epoch.
Mineralization on this series of irregular lensing quartz-calcite veins, some of coarse-grained, banded quartz, minor calcite, and crushed rock, containing fine-grained, free gold with minor silver, iron and manganese staining and sparse copper and lead sulfides and molybdates, deeply oxidized. Others, with more calcite, contain more copper and lead minerals. Wall rock is Cretaceous rhyolitic tuff and andesite. The gold is uniformly distributed in the veins but generally favors the footwall and is only rearely found in the hanging wall.
Workings include shaft operations. It is developed to a depth of 180 feet or more (76.2 meters) by drifts and shafts aggregating about 3,000 feet (914.4 meters) of work. A 5-stamp mill, then a 10-stamp mill, were erected on the property. This mine group was discovered in the 1890's but worked mainly for gold in 1907-1908. Minor lead-copper production in 1929-1930 and 1937. Total output was some 100 tons of 0.43 oz. Au/T and 0.5 oz. Ag/T ore and some 40 tons of 6% Pb, 4% Cu and 12 oz. Ag/T ore.
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Map Reference: 31°34'18"N , 110°46'10"W
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