Sodalite

Sodalite is a rare mineral. Hackmanite is an important variety of sodalite exhibiting tenebrescence. Originally discovered in 1806, it was not until vast deposits of good grade sodalite were found in Ontario that it became popular. It is used for ornamental objects, such as cabochons, beads and carved animals.

Color: White, blue and grey

Color of streak: White

Moh’s hardness: 5½-6

Density: 2.14-2.40

Cleavage: Indistinct

Fracture: Uneven, conchoidal

Crystal system: (Cubic) rhombic dodecahedra

Chemical composition: (Na4Al3(SiO4)3Cl) Sodium aluminium silicate with chlorine

Transparency: Transparent to opaque

Refractive index: 1.48

Double refraction: None

Dispersion: .018 (.009)

Pleochroism: Absent

Absorption spectrum: Not diagnostic

Fluorescence: Strong orange