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Attapulgus clay (attapulgite or palygorskite) is a magnesium aluminum phyllosilicate [(Mg.Al)₂Si₄O₁₀.4H₂O) which occurs in a type of clay soil common to the Southeastern United States. It is one of the types of fuller’s earth.

The name attapulgite is derived from the U.S. town of Attapulgus, Georgia, in the extreme southwest corner of the state, where the mineral is abundant. It is surface-mined in the area, dry-ground and air-separated into precise particle sizes, and transported in covered hopper cars via the railroad, and is also shipped in 50-lb bags and bulk bags by truck. The name palygorskite is given after the place in the Ural Mountains where it was discovered.

Attapulgite clays are swellable clays like bentonite, although more acicular (or needle like). Attapulgite, unlike bentonite, will swell in salt water and is used in special salt water drilling mud for off shore oil drilling. Like many clays, they can be considered as charged particles with zones of positive and negative charges. Standard attapulgite clays are agglomerated bundles of clay particles between 20 and 100 µm long and below 1 µm in diameter. Most grades contain up to 25% non-attapulgite material in the form of mineral carbonates and other inclusions. The advantage of attapulgites is that their performance is not temperature sensitive and they have lower water demand. They must have free ions in an aqueous system to work.

See also: Clay Minerals, Clay Treating Process.