Regional Report: Greaterville District, Santa Rita Mts, Pima Co., Arizona, USA

‡Ref.: Hill, J.M. (1910a) Notes on the placer deposits of Greaterville, Arizona, in Gold and silver, in Contributions to economic geology, 1909; Part I - Metals and nonmetals except fuels: U.S. Geological Survey Bulletin 430, p. 11-22. Schrader, F.C. & J.M. Hill (1915), Mineral deposits of the Santa Rita and Patagonia Mountains, Arizona, USGS Bull. 582: 152-153. Galbraith, F.W. & D.J. Brennan (1959), Minerals of Arizona: 42, 50, 85. Keith, Stanton B. (1974), Arizona Bureau of Geology & Mineral Technology, Geological Survey Branch Bull. 189, Index of Mining Properties in Pima County, Arizona: 120 (Table 4). Anthony, J.W., et al (1995), Mineralogy of Arizona, 3rd. ed.: 158. Arizona Bureau of Mines file data. A Au-Pb-Ag-Cu-Zn mining area located in T.19S., R.15-16E., in the north-central portion of the Santa Rita Mountains, in continuance of the district from the South in Santa Cruz Co. Bordered on the West by the Old Baldy District and on the NE by the Helvetia-Rosemont District. It is about 6 miles wide and extends from Box Canyon southward across the Pima-Santa Cruz County line to Old Baldy Peak, 7 miles distant and 9,432 feet in elevation. It is traversed in its western half the crest of the Santa Rita Mountains. This district was discovered as early as the early 1870's and probably in the 1860's. Bedrock in the northern part consists mainly of granite, including the axis of the range, on the west and Cambrain (?) quartzite on the east, against both of which is faulted a NW-SE belt of Devonian limestone on the south, which in turn, beginning on the east, is succeeded by overlying Mesozoic sediments, andesite, and rhyolite, the last rising to the summit of Old Baldy Peak. Both the granite and the Paleozoic and Mesozoic sediments are intruded by dikes and masses of rhyolite and granite porphyry, and a conspicuous stock of granite porphyry, known as Granite Mountain, occurs a mile and a quarter SW of Greaterville. Granite Mountain is knob-shaped and about half a mile in diameter. It rises 500 feet above the surrounding surface and is associated with the mineral deposits. Quaternary gravels overlie the granite on the NW and the Mesozoic and other formations on the east. Mineralization is varied: (1) Relatively coarse and angular flakes and nuggets of gold occurred in irregularly distributed gravels, both in present and past stream channels and terraces. The source was scattered mineralized veins in the mountains; and, (2) Scattered quartz and calcite veins with free gold or oxidized base metal sulfides in block-faulted Cretaceous sediments and Precambrian granite that was intruded by Laramide quartz latite and associated dikes, surrounding Granite Mountain. These veins are commonly banded and usually contain barite as a gangue mineral where they are in or associated with the granitic rocks. Workings include numerous placer operations and relatively small mines. Placer production since the 1870's by various estimates and records is some 18,500 oz. of placer gold with about 6,000 oz. of silver. Mine production would be some 2,000 tons of ore containing about 20 tons of Cu, 170 tons of Pb, 16 tons of Zn, 390 oz. of Au, and 12,660 oz. of Ag.

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