Oregon Mine, Oregon-Prompter mine group, Tombstone District, Tombstone Hills, Cochise Co., Arizona, USA
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|Location is approximate, estimate based on other nearby localities.|
|Latitude & Longitude (WGS84):||31° North , 109° West (est.)|
|Margin of Error:||~91km|
|Other regions containing this locality:||Sonoran Desert, North America|
|Köppen climate type:||BSk : Cold semi-arid (steppe) climate|
‡Ref.: Jones, E.L., Jr. & F.L. Ransome (1920), Deposits of manganese ore in Arizona, USGS Bull. 710-D: 114-116.
Wilson, E.D. & G.M. Butler (1930), Manganese ore deposits of Arizona, Arizona Bureau of Mines Bull. 127: 47, 48-50.
Butler, B.S., et al (1938b), Geology and ore deposits of the Tombstone district, Arizona, Arizona Bureau of Mines Bull. 143.
Rasor, C.A. (1939), Manganese mineralization at Tombstone, Arizona, Economic Geology: 34: 790-803.
Romslo, T.M. & S.F. Ravitz (1947), Arizona manganese-silver ores, U.S. Bureau of Mines Report of Investigation 4097.
Havens, R., et al (1954), Benefaction of oxide manganese and manganese-silver ores from southern Arizona, U.S. Bureau of Mines Report of Investigation 5024.
Galbraith, F.W. & D.J. Brennan (1959), Minerals of Arizona: 30.
Hewett, D.F. & M. Fleischer (1960), Deposits of the manganese oxides, Economic Geology: 55: 1-55.
Anthony, J.W., et al (1995), Mineralogy of Arizona, 3rd. ed.: 104, 342.
A Ag-Mn-Au mine located in the southern border area of secs. 14 & 15, T.20S. R.22E., 1½ miles SW of Tombstone. The Prompter workings equate to the eastern part of the Oregon Mine. Started about 1916. Owned by the Boston & Arizona Smelting & Reduction Co. and the Tombstone Development Co.
Mineralization is irregular, pipe-like to tabular replacement orebodies, mainly oxidized manganiferous-silver ores, along the footwall of the Prompter fault zone in Pennsylvanian-Permian Naco Group limestone and controlled by bedding plane slips and 'northeast' fractures.
The Prompter fault-fissure, a branch of the strong E-W fault which passes north of Military Hill. In the vicinity of the mine the fault brings the Naco Limestone on the north against the Abrigo Limestone, Bolsa Quartzite and Precambrian granite on the south. It dips 65º to 70ºS., and the fault is therefor of the reverse type. The fissure is occupied for at least a part of its length by a decomposed porphyry dike.
The Oregon shaft is sunk on the Oregon slip - a fissure close to the main fissure, which branches in a N.60ºW. direction from the Prompter fault-fissure and is entirely in the Naco Limestone. This slip dips 70º to 85ºNE and as a rule is accompanied by no gouge or breccia. An inclined winze goes down on a body of ore to an additional depth of 300 feet from the 300 level of the Oregon shaft. The orebodies in the Oregon workings occur as irregular, more or less tortuous pipes of rudely circular cross-section. At least 8 of these are known and average about 10 feet (3 meters) wide. They generally occur along lines of intersection of the Oregon slip with less conspicuous cross fissures. The orebodies have no definate walls except where they happen to be bounded on one side by a wall of the main fissure.
Workings include the Oregon shaft, a vertical, 300 foot deep shaft with a 300 foot deep winze from its 300 foot level. Connected by a tunnel through the hill with the area of the Prompter shaft. Ore contained 7.78 oz. Ag/T (1917).
2 valid minerals.
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