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Bobtail Mine (Virginia Mine; Missouri Mine; Mariana Missouri Mine; Twentieth Century claims; Wisner-Glassburn property; Mariana property; Bobaway property; Doak group), Pinal Peak area, Pinal Mountains District, Pinal Mts, Gila Co., Arizona, USA
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Latitude: 33°16'22"N
Longitude: 110°51'47"W
A former surface and underground Ag-Cu-Au-W-Pb-Zn mine located in sec. 12, T2S, R14E, about 2 miles WSW of Pinal Peak, about 2½ miles NW of Pioneer Mountain, and 8-10 miles SW of Globe, southern part of the Pinal Mountains, on National Forest land. Discovered 1898. Closed 1950. Claims extend into sec. 7, T2S, R15E. Operators included the Pandora Copper Co. (1915); the Bobtail Development Co.; Kilpatrick Brothers; the Tulsa Minerals Corp. (1945-1947); Rodengarten (1926); C. H. Foerester and J. Belcher (1940).

Mineralization is a pinch and swell ore body, 0.3 meters wide, hosted in the Algonkian Pinal Schist. It is a strong vein of sulfide ore, including native copper. The ore zone strikes N30E to N55E and dips N37W to N62W. An associated rock units are the Schultze Granite, diorite and diabase. Ore concentration was the result of intrusions of granite, diorite and diabase into the schist that have caused variations in the strike and dip of the planes of schistosity. The Bobtail vein carries little or no tungsten value. The tungsten vein contains sparse tungsten minerals.

No detailed geologic map of the area is available. NE-trending Early Tertiary Schultze Granite dikes are common throughout the district, as are outcrops of Madera Diorite (Precambrian). Mineralization is associated with an Early Tertiary Schultze Granite intrusion.

Workings include several shallow pits and open cuts. Two short adits are also located on the property, includes an inclined shaft, 75 feet deep, and an adit, 235 feet long. Workings total 304.8 meters in length and 66.45 meters in depth. No tungsten production was recorded.

Mineral List


10 entries listed. 9 valid minerals.

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The Resources of Arizona - A Manual of Reliable Information Concerning the Territory, compiled by Patrick Hamilton (1881), Scottsdale, AZ: 65.

Ransome, F.L. (1903) Geology of the Globe Copper District, Arizona, USGS PP 12: 161.

University of Arizona Bull. 41 (1916-17), Mineralogy of Useful Minerals in Arizona: 56.

A.I.M.E. Ore Deposits of the Western States (1933): 605.

Wilson, E.D. (1941), Arizona Bureau of Mines Bull. 148: 29.

Dale, V.B. (1961), Tungsten Deposits of Gila, Yavapai, and Mohave Counties, Arizona, US Bureau of Mines Information Circular 8078: 3-7.

Anthony, J.W., et al (1995), Mineralogy of Arizona, 3rd. ed.: 423.

USGS Pinal Peak Quadrangle map.

Arizona Department of Mineral Resources Bobtail group file.

Arizona Department of Mineral Resources U file, Cu18 and W10.

Arizona Department of Mineral Resources Twentieth Century Mine file.

MRDS database Dep. ID #10102398, MRDS ID M000370; and Dep. ID #10258459, MAS ID #0040070197.

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