- 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. 2018
- any of a group of minerals consisting of hydrated aluminium silicates: the major constituents of clays