Meaning of saponite

sap•o•nite

Pronunciation: (sap'u-nīt"), [key]
— n.
  1. a clay mineral, hydrous magnesium aluminum silicate, belonging to the montmorillonite group: found as a soft filling in rock cavities.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.