Description
The mineral stilbite is a highly hydrated sodium-calcium-aluminum silicate with the chemical formula NaCa4Al8Si28O72·30(H2O). This tecto-silicate belongs to the zeolites. Stilbite, which can be (cream) white, yellow, red, or brown, has a pearly to vitreous luster and a white streaked color. Its average density is 2.15 and its 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 word stilbe, meaning "shine," due to the mineral's pearly to vitreous luster. Stilbite is a common zeolite formed in amygdaloidal fissures in basalts, such as pegmatites. There is no defined type locality, but the mineral has been studied in Iceland, Andreasberg in the German Harz Mountains, the Dauphine Alps, and Norway.
