Fullers Earth / Clay Which is scientifically known as calcium bentonite. Fullers Earth/Clay is another range of bentonite product offered by us. Attapulgus Clay/Fullers Earth are used to remove polar contaminants from lube oils, waxes, fuels such as ATF & HSD. Fullers earth is in powdered form of uniform sized particles. These particles contain complex multi-centered crystalline structures of oxides and hydroxides of magnesium, aluminum and silicon.