Gelling clays being chemical thickeners for use in the manufacture of fertilizers, animal foodstuffs and plastic materials, namely, attapulgite, palygorskite, fuller's earth, sepiolites, chemically processed attapulgite, specially processed attapulgite; thickening mineral substances used as gelling agent in the manufacture of fertilizers, animal foodstuffs and plastic materials, namely, attapulgite, palygorskite, fuller's earth, sepiolites, chemically processed attapulgite, specially processe...