natural and synthetic clays and silicates, for example natural silicas such as diatomaceous earths; magnesium silicates, for example talcs; magnesium aluminum silicates, for example attapulgites and vermiculites;aluminum silicates, for example kaolinites, montmorillonites and micas; calcium carbonate; calcium sulfate; ammonium sulfate; synthetic hydrated silicon oxides and synthetic calcium or al