Stilbite is a tectosilicate mineral, belonging to the zeolite group of minerals. Since some 20 years stilbite is used to indicate a series of tectosilicate minerals in the zeolite group. Chemically it is a hydrated calcium sodium aluminium silicate, with the contents of calcium and sodium varying. It is usually white, sometimes with pinkish or greenish hues. Most often monoclinic, but may also be triclinic or orthorhombic. The crystal habitat may range from tabular to fibrous, with spherical and radial forms also common. It usually occurs in volcanic rocks and has industrial uses in treatment of hydrocarbons, for example petroleum refining. This specimen, actual width 110 mm, is from the Garrawilla volcanics in New South Wales, Australia.