The main uses of Bentonite Powder are for drilling mud, binder (e.g. foundry-sand bond, iron ore pelletizer), purifier, absorbent, and as a groundwater barrier. Bentonite possesses thixotropic properties and deposits a thin waterproofing film on the walls of the boreholes & thus renders permeable formations impermeable. Bentonites are aluminate silicate and can contain crystalline silica. The content varies widely from less than 1% to about 24%. Bentonite minerals occur as lenses or seams containing up to 50% moisture. They are rocklike in nature and usually extracted by opencast mining.