Definition of smectite in English:



mass noun
  • A clay mineral (e.g. bentonite) which undergoes reversible expansion on absorbing water.

    • ‘Common clays are usually mixtures of clay minerals such as illite, smectite, and kaolinite, together with fine silica and other minor constituents.’
    • ‘The lake may have dried up or nearly dried up periodically, producing outward concentric zones of albite, analcime, clinoptilolite, and smectite.’
    • ‘The limestone-dolomite breccia is characterized by abundant palygorskite, minor sepiolite, rare kaolinite and near absence of smectite.’
    • ‘The clay mineral smectite, with physical properties that make it unsuitable as a soil if it is wet, is only found in major amounts in covered stadiums.’
    • ‘The clay is composed of illite and kaolinite, with minor amounts of chlorite and smectite.’


Early 19th century: from Greek smēktis ‘fuller's earth’ + -ite.