Heulandite is found with other zeolite minerals filling cavities in granites, pegmatites, and basalts. Typical occurrences are in Berufjördhur, Ice.; on islands near Bombay; on the Faroe Islands; and in northeastern New Jersey. Heulandite is a member of a group of zeolite minerals with a characteristic platy habit.

How is Heulandite formed?

Heulandite occurs with stilbite and other zeolites in the amygdaloidal cavities of basaltic volcanic rocks, and occasionally in gneiss and hydrothermal veins. It forms at temperatures below about 100 °C (212 °F), and so its presence in sedimentary rocks indicates that these have experienced shallow diagenesis.

How do I know if I have Heulandite?

Heulandite creates sprays of complex translucent crystals exhibiting soft color hues. Its colors range from clear to white, pink, yellow, green, grey, brown, and black. It can be vitreous or pearly, and it can exhibit a translucent to a transparent luster. Heulandite is often mistaken as Stilbite.