Lau'mo-nite, n.

(49), n. [From Dr. Laumont, the discoverer of it.] (Min.) A mineral, usually transparent or translucent, of a white color and vitreous luster, and consisting chiefly of the hydrous silicate of alumina. Exposed to the air, it becomes opaque, and crumbles. [Written also laumontite.] Dana.