[mass noun] A clay mineral of a group resembling micas, with a lattice structure which does not expand on absorption of water.
- ‘Clay minerals are mainly illite and chlorite, with only traces of smectite, vermiculite and kaolinite.’
- ‘Common clays are usually mixtures of clay minerals such as illite, smectite, and kaolinite, together with fine silica and other minor constituents.’
- ‘The clay is composed of illite and kaolinite, with minor amounts of chlorite and smectite.’
- ‘The clay minerals illite, chlorite and montmorillonite were identified within the palaeosols by X-ray diffraction.’
- ‘In this case the surrounding sediment matrix is dominated by detrital quartz and illite along with various other clay minerals.’
1930s: from Illinois + -ite.