zeolite

from WordNet (r) 3.0 (2006)

zeolite
    n 1: 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

from The Collaborative International Dictionary of English v.0.48

Zeolite \Ze"o*lite\, n. [Gr. ? to boil + -lite: cf. F.
   z['e]olithe.] (Min.)
   A term now used to designate any one of a family of minerals,
   hydrous silicates of alumina, with lime, soda, potash, or
   rarely baryta. Here are included natrolite, stilbite,
   analcime, chabazite, thomsonite, heulandite, and others.
   These species occur of secondary origin in the cavities of
   amygdaloid, basalt, and lava, also, less frequently, in
   granite and gneiss. So called because many of these species
   intumesce before the blowpipe.
   [1913 Webster]

   {Needle zeolite}, needlestone; natrolite.
      [1913 Webster]