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

"So if the bentonite stays in place, we are safe," he said.

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

El Hachemi Bouali, assistant professor of geosciences at Nevada State College, said it all comes down to clay — bentonite and montmorillonite, to be specific.

From Los Angeles Times • Mar. 6, 2023

Moss agates, lithograph stones, asbestos, bentonite, gypsum, glass from native sand, and soda added to Wyoming's collection, which in variety was as great as any exhibit in the Mines Department.

From Final Report of the Louisiana Purchase Exposition Commission by Louisiana Purchase Exposition Commission