Description
The mineral sodalite is a chlorine-containing sodium aluminum silicate with the chemical formula Na8Al6Si6O24Cl2. The tectosilicate belongs to the feldspathoids. White, gray, pink, green, or azure-blue sodalite has a vitreous to oily luster, a white streak color, and poor cleavage along the crystal plane [110]. Its average density is 2.29 and its hardness is 6. The crystal system is cubic, and the mineral is not radioactive. The name of the mineral sodalite is derived from its chemical composition; sodium is the English word for "sodium." Sodalite occurs primarily in nepheline syenites, phonolites, and other felsic, silica-poor igneous and metamorphic rocks. The type locality is located in the Ilimaussaq Massif in Greenland.
