Bentonite

Bentonite is a naturally occurring clay generated from the alteration of volcanic ash, consisting predominantly of smectite minerals. The term bentonite was first used for a clay discovered in about 1890 near Fort Benton, Wyoming, USA. The main constituent of bentonite is the clay mineral montmorillonite, which is the determining factor in the clay's properties. This term in turn, derives its name from a deposit at Montmorillon, in Southern France.

Bentonite clay has remarkable sealing abilities when exposed to water and, therefore, it is used widely for environmental protection purposes in the construction and rehabilitation of landfills or waste sites to isolate the groundwater supply from the waste material. The old age of the known bentonite deposits across the world is a testament to the long-term physical and chemical stability of this clay material.

Bentonite also commonly serves as the main protective layer in geosynthetic clay liners and in a vast number of other applications from paper to food industry.