Kyanite mineral. Kyanite, also known as disthene, is an alumino-silicate mineral (Al2SiO5). It occurs in metamorphic rocks, in which it stands out by its soft to mid blue colouring. It occurs most usually in a prismatic to acicular crystal habitat, the crystal system being triclinic. Kyanite has industrial uses in refractory and ceramic products. Specimen from Minas Gerais, Brazil. Actual width of sample is 105 millimetres.