The Fuller’s Earth Industry: Florida-Georgia District

Fuller’s earth is an inexact term applied to certain clays that have a marked ability to adsorb coloring materials from animal, vegetable, and mineral oils. Many clays have this adsorbing power to a slight or very limited degree, and certain other clays, chiefly bentonites, as well as minerals such as bauxite, can be made highly adsorbent by activation with acids or alkalies, but the term fuller's earth is generally reserved for clays that are naturally highly adsorptive. In most fuller's earths and practically all activable clays montmorillonite is a dominant mineral. No definite clay mineral or group is implied in the name fuller's earth, and the distinction between fuller's earth and other clays that have more or less bleaching power is not sharply drawn. The name as generally used has no genetic or mineralogical significance. The fuller's earth produced in the Florida-Georgia district contains the clay mineral attapulgite. This mineral name was first used in 1930 by DeLapparent to apply to a hydrous aluminum magnesium silicate found in the fuller's earth from Attapulgus, Ga., and Quincy, Fla. An essential component of its structure, determined by Bradley in 1940, is that the silica chains of the molecule are arranged similarly to those of the amphibole minerals. The fibrous nature of the lath-like crystals of attapulgite is apparent under magnifications reached by the electron microscope. The ideal formula, [(OH,), (OH), Mg, Si, 0,-4H,O], contains no aluminum, but there is considerable replacement of the magnesium by aluminum. In the classification of clay minerals, attapulgite is associated with sepiolite and polygorskite rather than with mont-morillonite.