Haüyne - Na,Ca)₄-₈Al₆Si₆(O,S)₂₄(SO₄,Cl)₁-₂

Habit: Bright blue to greenish blue, white or shades of black, gray, brown, green, yellow or red; may be patchy. Crystals dodecahedra or pseudo-octahedra; also rounded grains. Vitreous to greasy luster; transparent to translucent. Bluish white streak.

Environment: Occurs in phonolites and related leucite- or nepheline-rich igneous rocks, and less commonly in nepheline-free extrusives.

Etymology: Named in honor of Abbé René Just Haüy (1743-1822), a French crystallographer and mineralogist.