Source : Webster's Revised Unabridged Dictionary (1913)

Laumontite \Lau"mont*ite\, n. [From Dr. Laumont, the
   discoverer.] (Min.)
   A mineral, of a white color and vitreous luster. It is a
   hydrous silicate of alumina and lime. Exposed to the air, it
   loses water, becomes opaque, and crumbles. [Written also
   {laumonite}.]