any of a family of glassy minerals analogous to feldspar containing hydrated aluminum silicates of calcium or sodium or potassium; formed in cavities in lava flows and in plutonic rocks
Any of several minerals, aluminosilicates of sodium, potassium, calcium or magnesium, that have a porous structure (originally, those which swelled and gave off water when heated); they are used in water softeners and in ion exchange chromatography.