Explanation
Island structure silicate mineral. monomer is rare, sometimes in the shape of pseudo hexagonal short column, and in the shape of round cross section in rock. Slightly blue or purplish blue, sometimes also with light yellow or light brown. glass luster, fracture grease luster, shell like. Brittle, Mohs hardness 7-7.5, density 2 53? 2.78 g/cm3. It is mainly produced in gneiss and crystalline schist, coexisting with biotite, amphibole, basic plagioclase and sillimanite. Those with bright colors can be used as gems.
Classification
Natural materials and products -> Mineral materials