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

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

Millions of years ago a volcanic eruption deposited ash that became bentonite clay.

From Los Angeles Times • Mar. 22, 2024

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

A series of barriers—giant copper casks, water-absorbing bentonite clay, and water-resistant crystalline rock—are expected to protect harmful radionuclides from seeping out of the site and into the local ecosystem.

From Science Magazine • Mar. 4, 2022

The layer had a definite relation to the seams of bentonite, and, with this additional evidence, I was confident there was no possible chance of a mistake.

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