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Silver Spur Mine (Old Frijole Mine), Frijole claim group, Helvetia, Helvetia-Rosemont District, Santa Rita Mts, Pima Co., Arizona, USA

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Latitude & Longitude (WGS84): 31° 50' 57'' North , 110° 46' 2'' West
Latitude & Longitude (decimal): 31.84917,-110.76722
Other regions containing this locality:Sonoran Desert, North America
Köppen climate type:BSk : Cold semi-arid (steppe) climate

‡Ref.: Schrader, F.C. & J.M. Hill (1915), Mineral deposits of the Santa Rita and Patagonia Mountains, Arizona, USGS Bull. 582: 92, 119.

Galbraith, F.W. (1947), Minerals of Arizona, Arizona Bureau of Mines Bull. 153: 27.

Creasey, S.C. & G.L. Quick (1955), Copper deposits of part of Helvetia Mining district, Pima County, Arizona, USGS Bull. 1027-F: 315.

Arizona Bureau of Mines field notes (1971), vol. 1, no. 2.

Drewes, H.D. (1971) Geologic map of the Sahuarita quadrangle, southeast of Tucson, Pima County, Arizona: U.S. Geological Survey Miscellaneous Geologic Investigations Map I-613, 1 sheet, scale 1:48,000.

Keith, Stanton B. (1974), Arizona Bureau of Geology & Mineral Technology, Geological Survey Branch Bull. 189, Index of Mining Properties in Pima County, Arizona: 128 (Table 4).

USGS Sahuarita Quadrangle topo map.

MRDS database Dep. ID file #10039416, MRDS ID #M050051; and, Dep. ID #10113205, MAS ID #0040190408.

A former small underground Ag-Cu-Pb-Au mine located in the SE¼SW¼ sec. 24, T.18S., R.15E., 1¾ miles SE of Helvetia, at an altitude of 4,900 feet, and about 28 miles SE of Tucson. Discovered in the late 1870's (1877 ?) and the oldest property in the camp. Produced 1880-1963. Owned at times, or in part, by Hart & Weigel (initial operators in early 1880's); Peter Lauterback; and, Barbre. Operators included D & P Mining Co.

Mineralization is quartz fissure vein associated with an aplite dike, with partly oxidized chalcocite and argentiferous galena, minor chalcopyrite and pyrite, cutting Precambrian granodiorite. The tabular ore body is 0.1 meters thick with a depth to bottom of 18.29 meters. Associated rock units include granodiorite at 54 ± 2 Y, and aplite.

The hydrothermal vein follows a fault. The upper fifty feet consists principally of 4 inches (10 cm) of massive, mineral-bearing, white quartz, but it narrows below the 60 foot level and pinches to a mere seam at the bottom of the shaft. A small, nearly flat-lying quartz vein with ore was encountered in the new workings.

Local structures include thrust and normal faulting, fracture zones, homoclinal. Regional trends include tilting and broad open folds in the south and extensive faulting in the north.

Workings include the old shaft at 100 feet deep, inclined 30º ESE. The newer workings are about 300 feet S. of the old and 200 feet above them and are comprised of a short tunnel. This property was worked sporadically from the late 1870's to 1963. It produced some 200 tons of ore averaging about 22 oz. Ag/T and 1% Cu and 1% Pb. Produced $40,000 of Ag (1880-1889)(period values).

Mineral List

5 valid minerals.

Regional Geology

This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.

Click on geological units on the map for more information. Click here to view full-screen map on

1400 - 1600 Ma

ID: 2830999
Middle Proterozoic granitic rocks

Age: Calymmian (1400 - 1600 Ma)

Stratigraphic Name: Oracle Granite; Ruin Granite

Description: Mostly porphyritic biotite granite with large microcline phenocrysts, with local fine-grained border phases and aplite. Associated pegmatite and quartz veins are rare. This unit forms large plutons, including the Oracle Granite, Ruin Granite, granite in the Pinnacle Peak - Carefree area northeast of Phoenix, and several bodies west of Prescott. (1400-1450 Ma)

Comments: ~ 1.4 Ga

Lithology: Major:{granite}, Minor:{aplite}, Incidental:{pegmatite}

Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052. [133]

Data and map coding provided by, used under Creative Commons Attribution 4.0 License

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