Color is clear, white, pink, yellowish, reddish and brown. Luster is vitreous. Crystals are transparent to translucent. Aggregates form crusts and granular masses. Twinning is common with the penetration twin rotated around the c-axis.
Cleavage is poor in three directions parallel to the faces of the rhombohedron.
Fracture is uneven. Hardness is 4 - 5. Streak is white. Unlike calcite, does not react to acids. Associated Minerals are quartz , calcite , scolecite , apophyllite , natrolite , heulandite , stilbite and other zeolites .