bentonite

American  

[ben-tn-ahyt] / ˈbɛn tnˌaɪt /

noun

Mineralogy.

1. a clay formed by the decomposition of volcanic ash, having the ability to absorb large quantities of water and to expand to several times its normal volume.

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bentonite British  

/ ˈbɛntəˌnaɪt /

noun

1. a valuable clay, formed by the decomposition of volcanic ash, that swells as it absorbs water: used as a filler in the building, paper, and pharmaceutical industries

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Other Word Forms

• bentonitic
  adjective

Etymology

Origin of bentonite

1895–1900; named after Fort Benton, Montana; see -ite ¹

Example Sentences

See Examples For:

bentonite

The canisters will be lowered into holes drilled in the tunnels, before the holes are filled with bentonite clay to seal them, Parviainen explained.

From Barron's ● Jun. 1, 2026

They blended it with modified starch and bentonite nanoclay, then added glycerol and polyvinyl alcohol to improve durability and flexibility.

From Science Daily ● Feb. 28, 2026

Collins, over at Washington State University, has been experimenting with spraying fine-powdered kaolin or bentonite, which are clays, mixed with water onto wine grapes so it absorbs materials that are in smoke.

From Washington Times ● Sep. 28, 2023

Layers of clay — bentonite and montmorillonite, to be specific — are found beneath the ground, interspersed between layers of bedrock.

From Los Angeles Times ● Jul. 13, 2023

Interbedded in the Boquillas flags there are some thin layers of bentonite, which are quite persistent and can be followed for several miles.

From Fossil Ice Crystals An Instance of the Practical Value of "Pure Science" by Johan August Udden