Nanoclay is a type of material made using nanotechnologies, it is a surface modified montmorillonite clay, or masterbatche containing modified clay that is utilized to make a nanocomposite. Nanoclays are generically referred to as "intercalates" in patent literature.

Natural clays are most commonly formed by the in situ alteration of volcanic ash. Nanoclay is made of volcanic minerals, or smectite, structured into plates of approximately one nanometer thick but several hundred nanometers in width and length. Nanoclays are natural nanomaterials that occur in the clay fraction of soil, among which montmorillonite and allophane are the most important species. Montmorillonite is a crystalline hydrous phyllosilicate (layer silicate). Organically modified montmorillonites or ‘organoclays' were formed by intercalation of quaternary ammonium cations. Allophane is a non-crystalline aluminosilicate derived from the weathering of volcanic ash.

Depending on chemical composition and nanoparticle morphology, nanoclays are organized into several classes such as montmorillonite, bentonite, kaolinite, hectorite, and halloysite. Organically-modified nanoclays (organoclays) are an attractive class of hybrid organic-inorganic nanomaterials.