Very rarely will it form distinct, well-individualized crystals showing a square-like cross-section, including those found at the Jeffrey Mine in Asbestos, Quebec, Canada.

Its hardness is 6.5, its specific gravity is 2.80–2.95 and its color varies from light green to yellow, but also colorless,[8] blue, pink or white.

Though not a zeolite, prehnite is found associated with minerals such as datolite, calcite, apophyllite, epidote, stilbite, laumontite, and heulandite in veins and cavities of basaltic rocks, sometimes in granites, syenites, or gneisses.

[4] It was named for Colonel Hendrik Von Prehn (1733–1785), commander of the military forces of the Dutch colony at the Cape of Good Hope from 1768 to 1780.

[9] Extensive deposits of gem-quality prehnite occur in the basalt tableland surrounding Wave Hill Station in the central Northern Territory, of Australia.