Latitude: 32°58'34"N
Longitude: 110°17'36"W
A former underground Cu-Pb-Zn-Ag-Fe mine located in secs. 21, 22, 27 & 28, T5S, R20E, 3.7 miles NE of Imperial Mountain, on National Forest land. Discovered by Julius Riser and W.A. Clark in 1905. Produced 1916-1957. Past operators include the Cobre Grande Co.; Mr. Julius Riser; and the Duval Sulphur and Potash Co. Owned by Snell, Elliot, Fisk, and Alderman of Globe, AZ (1920).
Mineralization is a tabular ore body hosted in Escabrosa Limestone; Horquilla Limestone and thin shale beds. The ore zone is 2.44 meters wide, strikes NNW and dips 85SW. Several zones of mineralization occur in more than one vein. Limestone is replaced in zones both across and parallel to bedding. Silicic dikes intrude the area. The entire area is closely faulted and highly altered. Relationships are obscure. Ore control was faults and bedding planes. Ore concentration was replacement and fissure filling. Alteration was oxidation and silicification. An associated rock unit is diorite.
Area structures include block faulting trending NNW. Regional trends: minor Pre-Cretaceous E- and NE-trending folds and major Post-Cretaceous NNW-trending faults.
Workings included one adit 700 feet long (Cowboy tunnel), raises, and winzes up to 30 feet deep. Workings achieved a depth of 48.77 meters.
References
Ross, Clyde P. (1925) Geology and ore deposits of the Aravaipa and Stanley mining districts, Graham County, Arizona, USGS Bull. 763: 102-103.
Denton, T.C. (1947), Aravaipa lead-zinc deposits, Graham County, Arizona, U.S. Bureau of Mines Report of Investigation 4007: Figure 3, 5.
Simons, F.S. (1964) Geology of the Klondyke Quadrangle Graham and Pinal Counties. USGS Professional Paper 461: 135-136, Plate 1.
Brown, S.D. (1993) Mineral Appraisal of the Coronado National Forest, part 10, Santa Teresa Mountains Unit, Graham County, Arizona, U.S. Bureau of Mines Open File Report MLA 26-93, 53 pp.
Anthony, J.W., et al (1995), Mineralogy of Arizona, 3rd.ed.: 246.
USGS Cobre Grande Mountain Quadrangle map.
Arizona Department of Mineral Resources Cobre Grande Mountain file.
Arizona Department of Mineral Resources U file.
MRDS database Dep. ID #10039447, MRDS ID #M050093; and Dep. ID #10185895, MAS ID #0040090024.
Mineral List
9 entries listed. 6 valid minerals.
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