Minerals (Category B)
FULLER'S EARTH are the important naturally occurring clays of great commercial importance possessing inherent bleaching properties. They are, therefore commonly called bleaching clays. They fall mainly under montmorillonite group containing a varying amount of attapulgite. The montmorillonite is designated by the chemical formula (OH4).Si8.O20.nH2O. The clay minerals of montmorillonite and attapulgite groups are distinguished by their adsoption characteristics. The chemical composition of these clays is similar to that of other common clays and it is rarely that these clays can be identified by chemical analysis. It is by X-rays, D.T.A., electron microscopic as well as by staining techniquished. The natural activity in the clay is determined by actual trials. The other important property of the montmorillonite group of minerals is possession of exchangeable ions.