Titanite - CaTiSiO₅

Habit: Black, brown, gray, colorless, green, yellow or red. Can be wedge-shaped and also as prismatic crystals; sometimes metamict. Vitreous to greasy luster; transparent to opaque. Reddish white streak.

Environment: A common accessory mineral in igneous and metamorphic rocks; less common in volcanic rocks.

Etymology: From the titanium in its composition.