(mineralogy) A mineral, of a white color and vitreous luster, with the chemical formula CaAl2Si4O12·4H2O. It is a hydrous silicate of alumina and lime. Exposed to the air, it loses water, becomes opaque, and crumbles.
Origin of laumontite
Named after the discoverer François Pierre Nicholas Gillet de Laumont (1747–1834) as lomonite, renamed as laumonite in 1809 and as laumontite in 1821. + -ite