A Bentonite is a colloidal clay, expansible when moist, commonly used to provide a tight seal around a Well casing.

See also:
"Bentonite" is in the Code "2508.10"
- - Bentonite

"Bentonite" is in the UNSPSC Code "11111804"
Bentonite

"Bentonite" is in the NAICS Code "212325"
Clay and Ceramic and Refractory Minerals Mining
Bentonite mining and/or beneficiating