Luster is vitreous. Transparency crystals are translucent to opaque. The terminations are modified and slanted dome faces. Also found massive and in disseminated grains. Cleavage is perfect in two direction at 80 and 100 degree angles.
Fracture is splintery.
Streak is reddish-brown. Associated Minerals are benitoite , natrolite , serpentine , aegerine and joaquinite . Notable Occurrences include the famous San Benito Co., California site as well as Narsarssuk Greenland and the Kola penninsula, Russia. Best Field Indicators are crystal habit, internal reflection, streak, associations, color, and cleavage.