Any natural earthy material that decolorizes mineral and vegetable oils and has high sorbent capacity for water and oil. The term fuller's earth has no genetic or mineralogic significance. However, the most common earthy materials classed as fuller's earth are calcium montmorillonites and palygorskites (attapulgites) and sepiolites. The term originated in England, where in ancient times raw wool was cleaned by kneading it in water with clay materials that adsorbed dirt and lanolin. The process was known as fulling, and the clay or earth became known as fuller's earth.