Habit: Brown or greenish brown to black. Prismatic crystals, granular or massive. Vitreous luster; semitransparent. Grayish white streak.
Environment: Commonly occurs in rapidly cooled siliceous volcanic rocks. Inverted varieties with exsolved augite found in layered mafic intrusives; also in metamorphosed iron formations.
Etymology: From its occurrence at Pigeon Point, Minnesota, in the United States.