Color is usually dark blue, black, very dark brown to red-brown. Luster is adamantine to submetallic. Diaphaneity is opaque to translucent.
Fracture is subconchoidal to uneven.
Hardness is 5.5 - 6. Streak is white to grey. Associated Minerals include aegirine, albite, analcime, biotite, calcite, dolomite, elpidite, natrolite, quartz and siderite.