Color varies from dark brown to red-brown to black. Luster is vitreous to greasy. Diaphaneity is opaque. Crystal Habits include the short prismatic crystals to 3mm.
Fracture is conchoidal to uneven.
Hardness is 5.5 - 6. Streak is gray. Associated Minerals include aegirine, allanite, calcite, fluorite, grossular, microcline, prehnite, pyrrhotite and titanite.