Definition of montmorillonite in US English:



  • An aluminum-rich clay mineral of the smectite group, containing some sodium and magnesium.

    • ‘The three investigators found that a porous clay called montmorillonite, already known to encourage the linking of nucleic acids, also has an effect on fatty acids, the building blocks of cell membranes.’
    • ‘To test their theory, the researchers added small particles of montmorillonite - a clay widespread in the environment.’
    • ‘Ancient deposits of weathered volcanic ash containing the special healing mud known as montmorillonite have been found on a farm 15 km east of Northampton.’


Mid 19th century: from Montmorillon, the name of a town in France, + -ite.