bentonite
/ˈbentənaɪt/noun
mass noun
- a kind of absorbent clay formed by breakdown of volcanic ash, used especially as a filler膨润土, 皂土, 斑脱土（由火山灰分解而形成的一种黏土, 吸水性强, 尤用作填料）。
词源
late 19th cent.: from the name of Fort Benton in Montana， US， where it is found， + -ITE1.