bentonite: Meaning and Definition of

ben•ton•ite

Pronunciation: (ben'tn īt"), [key]
— n. Mineral.
  1. a clay formed by the decomposition of volcanic ash, having the ability to absorb large quantities of water and to expand to several times its normal volume.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.
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