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a mineral, natural aluminum hydroxide, AIOOH; contains 85 percent AI2O3 and 15 percent H2O, often with impurities of iron, chromium, manganese, and gallium oxides. Diaspores crystallizes in a rhombic system, forming lamellar, sometimes acicular, crystals. Its color is white, yellowish or pinkish white, or greenish gray. Its hardness on the mineralogical scale is 6–7; its density varies depending on the content of impurities, from 3,300 to 3,500 kg/m3. When annealed it becomes α-Al2O2 (corundum).
Diaspore is mainly concentrated in bauxites, where it appears as an ore-forming mineral together with boehmite and gibbsite. In association with corundum and chloritoids, it is found in emery deposits that are produced by the metamorphic change of bauxites. Diaspore is found in metamorphic, hydrothermic; and metasomatic deposits of the secondary quartz type.