Its origin is disputed though it is primarily found in peralkaline volcanic rocks, pegmatites, and granites as well as silica-poor intrusive rocks.
Characteristics[edit | edit source]
Its structure consists of single tetrahedral chains with a repeat unit of four and complex side branches. It forms blue to colorless, typically massive crystals in the hexagonal crystal system. It has a Mohs hardness of 5.5 to 6 and a specific gravity of 2.55 to 2.65. It has refractive index values of nω=1.523 and nε=1.529. It has one direction of perfect cleavage and exhibits conchoidal fracture. It fluoresces a bright orange.