Analcime, or analcite, is a colourless, white to grey tectosilicate mineral, often classified as a zeolite mineral, but structurally and chemically it is more akin to feldspar. It consists of hydrated sodium aluminium silicate (NaAlSi2O6廈2O) and belongs to the cubic crystal system. Well developed crystals typically occur in the form of stocky trapezohedrons, like those in this sample from the Seisser Alm in South Tirol, Italy. Analcime occurs as a primary constituent in analcime basalt and other alkaline igneous rocks. Actual width of sample is 100 mm.