Papago District (Sierrita District), Sierrita Mts, Pima Co., Arizona, USA

‡Ref.: Ransome, F.L. (1922) Ore deposits of the Sierrita Mountains, Pima County, Arizona, in Contributions to Economic Geology (Short Papers and Preliminary Reports), 1921 - Part I.--Metals and Nonmetals except Fuels: U.S. Geological Survey Bulletin 725, p. 407-428.

Galbraith, F.W. & D.J. Brennan (1959), Minerals of Arizona: 102.

Keith, Stanton B. (1974), Arizona Bureau of Geology & Mineral Technology, Geologidcal Survey Branch Bull. 189, Index of Mining Properties in Pima County, Arizona: 131 (Table 4).

Drewes, Harald D., and Cooper, J.R. (1973) Reconnaissance geologic map of the west side of the Sierrita Mountains, Palo Alto Ranch quadrangle, Pima County, Arizona: U.S. Geological Survey Miscellaneous Field Studies Map MF-538, 1 sheet, scale 1:24,000.

Anthony, J.W., et al (1995), Mineralogy of Arizona, 3rd. ed.: 400.

A Ag-Pb-Cu-Zn-Mn-Mo-F-U mining area located in T. 17-18 S., R.10-11E., on the West side of the Sierrita Mountains.

Mineralization is varied: (1) Bands of folded and faulted Palaeozoic and Mesozoic sedimentary and volcanic formations intruded by Mesozoic and Laramide granitic intrusives. Spotty base and precious metal deposits, largely oxidized, with minor local molybdenum and traces of uranium, in irregular replacement orebodies or along faults and fractures; (2) Gold placers; and, (3) Fluorspar along fault veins.

Geologically, the district consists of roughly banded strips of partly metamorphosed Paleozoic quartzite, limestone, and dolomite; Mesozoic sediments and volcanics; Mesozoic granitic intrusives; and some offshoots of the large Laramide granitic pluton that makes up a large part of the Sierrita Mountains. These formations have been folded, faulted, and thrusted into a structural complex as revealed in the quadrangle mapping of Drewes & Cooper (1973).

Workings include mainly small mines and prospects worked sporadically since the 1870's. Total estimated and reported mine production would be some 5,000 tons of ore containing about 30,000 oz. of Ag, 400 tons of lead, 26 tons of copper, 1 ton of zinc, and 100 oz. of gold. About 1,000 oz. of gold may have been recovered from placers and a small amount of fluorspar has been shipped.