clay mineral

noun
  1. 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
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British Dictionary definitions for clay mineral

clay mineral

noun
  1. 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