böhmite

Böhmite is a mineral composed of aluminum oxide hydroxide, with the chemical formula AlO(OH). It is one of the three main polymorphs of aluminum oxide hydroxide, the others being diaspore and gibbsite. Böhmite crystallizes in the monoclinic crystal system. It is typically found as a secondary mineral, often formed by the weathering of aluminum-bearing rocks. It can also be found in bauxite deposits, which are the primary source of aluminum. The color of böhmite can range from white to grayish, and it often has a waxy luster. It is relatively hard, with a Mohs hardness of 3 to 3.5. Böhmite is an important constituent of many clays and is often associated with kaolinite. In industrial applications, böhmite is a precursor in the production of alumina, which is then used to smelt aluminum metal. It is also used in the manufacturing of ceramics, refractories, and as a fire retardant. Its dehydration at high temperatures yields alumina, making it a valuable intermediate in aluminum production. The mineral was named in honor of German chemist and geologist Johannes Böhm.