Mansfieldite is a rare aluminum arsenate hydrate, a member of the Variscite Group, and the aluminum analogue of scorodite. It forms orthorhombic, colorless to white or light gray, vitreous, crystals and often occurs as fibrous crusts and porous masses. Mansfieldite was named in 1948 for George R. Mansfield, an American geologist for the U.S. Geological Survey. Mansfieldite occurs with scorodite, realgar, and kaolinite at the type locality: Hobart Butte, Black Butte district, Lane Co., Oregon, USA. It also occurs at the Nelson Ridge area, Yakima Co., Washington; the Rain mine, Elko Co., and the Goldstrike mine, Eureka Co., Nevada, USA. At the Penberthy Croft mine, St. Hilary, Cornwall, England, UK; Alyaskitovoye Sn-W deposit, Ust-Nera, Sakha Republic, Eastern-Siberian Region, Russia; and at several occurrences in the Bou-Azer district, Tazenakht, Ouarzazate Province, Souss-Massa-Draa Region, Morocco.
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