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boehmite An aluminium hydrate γ-AlO(OH), boehmite forms a continuous series with its polymorph diaspore α-AlO(OH) and is a constituent of bauxite and laterite; sp. gr. 3.0; hardness 4; orthorhombic; usually white; normally occurs as microscopic grains, or pisolitic aggregates; cleavage good {010}; occurs extensively in the weathering profiles of rocks together with gibbsite, diaspore, and kaolinite. It is used for aluminium production and is named after the nineteenth-century German chemist J. B. Böhm.