Veins of hypogene manganese oxide minerals in the southwestern United States

Characteristic minerals are psilomelane, hollandite, cryptomelane, and coronadite, more rarely ramsdellite and pyrolusite. Host rocks are Mn-deficient; 80 percent of examples are middle to late Tertiary layered volcanics. Though deposits are shallow, mostly mined to only 100-200 feet (maximum 500 feet), a hypogene origin is indicated by their persistent association with barite and fluorite, a peripheral position in the zonal pattern of some metal-mining districts, alteration of plagioclase to K-spar, and abundance of W, Pb, Cu, Mo, Ti, As, Sb. They represent the subzone of Mn-bearing epithermal vein deposits lying nearest the surface, succeeded in depth by four other subzones: barite, fluorite, gold-silver, and base metals.

This record provided courtesy of AGI/GeoRef.

This article has been cited by other articles:

				K. M. Michailidis, K. Nicholson, M. K. Nimfopoulos, and R. A. D. Pattrick An EPMA and SEM study of the Mn-oxide mineralization of Kato Nevrokopi, Macedonia, northern Greece: Controls on formation of the Mn4+ oxides Geological Society, London, Special Publications, January 1, 1997; 119(1): 265 - 280. [Abstract] [PDF]