Bentonite generally describes clay consisting of essentially of the smectite Group of Minerals & composed mainly of Montmorillonite. It derives from the chemical change of glass of magmatic origin usually volcanic ash. The Bentonite deposits are extremely Heterogeneous. We generally describe two types of Bentonite as Sodium & Calcium. The unique properties of Bentonite are its swelling & water absorption. It absorbs water in a reversible manner. Its natural viscosity and thixotropy property make it very valuable clay for wide range use and application. Bentonite clay is fine-grained almost impalpable material, very soft and more or less coherent when dry of plastic and retentive of water when wet.
