any of a group of hydrous aluminum silicate minerals, as kaolinite, illite, and montmorillonite, that constitute the major portion of most clays.
Origin of clay mineral
First recorded in 1945–50
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
any of a group of minerals consisting of hydrated aluminium silicates: the major constituents of clays
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012