fuller's earth, mineral substance characterized by the property of absorbing basic colors and removing them from oils. It is composed mainly of alumina, silica, iron oxides, lime, magnesia, and water, in extremely variable proportions, and is generally classified as a sedimentary clay. In color it may be whitish, buff, brown, green, olive, or blue. It is semiplastic or nonplastic and may or may not disintegrate easily in water. It was originally used in the fulling of wool to remove oil and grease but is now used chiefly in bleaching and clarifying petroleum and secondarily in refining edible oils. Fuller's earth is mined in many parts of the United States, Georgia and Florida being the leading producers, and in England near Reigate, Nutfield, and Bath. Before it can be used, it has to be crushed and dried.
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