Attapulgite (also attapulgus, among other lesser-used or trademarked names) is a type of clay soil common to the Southeastern U.S. Its main use is in medicine, where it physically binds to acids and toxins in the stomach and digestive tract. For that reason, it is the "dirt" generally used in dirt eating . It was also the ingredient used in Kaopectate, before that product became pink bismuth subsalicylate in the 2000s. Like bismuth, it is not absorbed into the body, however the two work differently.
The town of Attapulgus, Georgia, at the extreme southwest corder of the state, is named for this substance which is surface-mined in the area. It is often carried in covered hopper cars (much like tanker cars) via railroad, mixed with water into a slurry.