Pollucite

Pollucite belongs to the zeolite group. It gets its name from Pollux, the twin brother of Castor, in Greek mythology. It is frequently found with petalite which was formally known as castorite. Facet grade material is prized by gemstone collectors and can be found in Afghanistan, Pakistan, Russia, and the United States. Pollucite is the most commercially important source of cesium which makes up a major constituent of its chemical formula.