BENTONITE is the important naturally occurring clay of great commercial importance possessing inherent bleaching properties. It is, therefore commonly called bleaching clay. It falls mainly under the montmorillonite group containing a varying amount of attapulgite. The montmorillonite is designated by the chemical formula (OH4).Si8.O20.nH2O… Bentonite is a clay generated frequently from the alteration of volcanic ash, consisting mainly of smectite minerals, usually montmorillonite. In addition to montmorillonite, bentonite may also contain quartz, feldspar, calcite, and gypsum. Bentonite displays strong colloidal properties and its volume increases several times when coming into contact with water, creating a gelatinous and viscous fluid. The special properties of bentonite (hydration, swelling, water absorption, viscosity, thixotropy) make it a valuable material for a wide range of uses and applications.