Raw Heulandite (Stilbite) from Pune India (Small groups) from India.

The mineral stilbite is a highly hydrated sodium-calcium-aluminum silicate with the chemical formula NaCa4Al8Si28O72·30(H2O). The tectosilicate belongs to the zeolites. The (cream) white, yellow, red or brown stilbite has a pearl to glass luster and a white stripe color. The average density is 2.15 and the hardness is 3.5 to 4. The crystal system is monoclinic and the mineral is not radioactive. The name of the mineral stilbite is derived from the Greek stilbe, meaning "shine". This is due to the pearl to glass luster of the mineral. Stilbite is a common zeolite that forms in amygdaloidal fissures in basalts, such as pegmatites. There is no defined type locality, but the mineral has been studied in Iceland, the Andreasberg in the German Harz, the Dauphinoise Alps and in Norway.