Bentonite

Bentonite is a powdery earth deposited from volcanic dust. The magic of Bentonite is that it expands when wet. As a result it has many uses. It is used for drilling mud in the oil and gas fields. It's used to coat the walls of water wells. Bentonite can be placed in areas of ponds and lakes that seep water as a sealer. It's a good clarifier of some wines.

Bentonite---------named for Ft. Benton Wyoming