Color is usually colorless or white. Luster is vitreous. Diaphaneity is transparent to translucent. Crystal Habits include the pseudotetragonal prisms, fibrous aggregates to 10cm, and crystalline masses.
Fracture is splintery.
Hardness is 4.5 - 5. Streak is white. Associated Minerals include amphibole group, annite, apophyllite series, calcite, fluorite, microcline, poudretteite, sodalite, vesuvianite and many others.