Explanation
Also called sillimanite or sillimanite. A type of aluminum silicate mineral. It is a isomorphic variant with andalusite and kyanite. Brown, light green, light blue, or white in color; Silk luster or glass luster. Columnar or needle shaped, aggregates in fibrous or radial shape. With a hardness of 7.5 and a density of 3.23-3.27g/cm3, it is a typical high-temperature metamorphic mineral, which is formed from aluminum rich argillaceous rocks through high-level regional metamorphism, and is mainly produced in crystalline schist and gneiss; It is also found in the contact zone between aluminum rich rocks and igneous rocks. It becomes mullite when heated to about 1500 ℃. It can be used to manufacture high alumina refractory and acid resistant materials; It is also the raw material for preparing technical ceramics, such as insulator of spark plug, cast steel crucible, high temperature measuring tube and silicon aluminum alloy used for aircraft, automobile, train and ship parts. Colorful sillimanite can be used as gems.
Classification
Natural materials and products -> Mineral materials