Sodalite - Na₈Al₆Si₆O₂₄Cl₂

Habit: Colorless, white, yellow, green, various shades of blue or reddish. Crystals rare; typically massive. Vitreous to greasy luster; transparent to translucent. White streak.

Environment: Found in nepheline syenites, phonolites, volcanic ejecta and metasomatized calcareous rocks.

Etymology: Named for its sodium content.