Bentonite is clay containing not less than 70% of montmorillonite. Montmorillonite is superfine flaky aluminosilicate, where due to lattice nestehiometrical cations exchange surplus negative charge appears and compensates cation-exchange located in interlayer area. High waterproofing is conditioned on this. In case of water tempering, water penetrates in interlayer area of montmorillonite, hydrates it's surface and cation-exchange, so that provides swelling of the mineral. During further water dilution bentonite forms firm viscous suspension with thixotropic properties. Montmorillonite has high cation-exchange and adsorption properties.
Owing to this properties bentonite has found wide application as viscous gelling agent and filtration diminishing agent in drilling muds production for well-boring, as binding agent in foundry sands and iron ore pellets and also as hydraulic and adsorption material.
In agriculture bentonite is used in mixed fodder production, as bedding for animal's, for melioration properties, and also for wine and juice clarification. Clumping cat litter is of the best quality produced from bentonite. It is common knowledge that bentonite has more than 200 spheres of application.
Bentonite has the best technical properties if montmorillonite contains exchanged sodium cations. The deposits of natural-sodium betonite are located in Transcaucasia. In Russia the most well-known are the deposits with 30—60% montmorillonite content, called bentonite by mistake. Practically, all Russian bentonite is calcium — magnesium. Consumer properties of such bentonite, containing not less than 70% of montmorillonite, after soda ash activation might approach to natural-sodium bentonite.