In 2005, the United States was the largest producer of fuller's earth with an almost 70% world share followed at a distance by Japan and Mexico. In the United States fuller's earth is typically derived from deposits of volcanic ash of Cretaceous age and younger (glacial clays do not form fuller's earth). Fuller's earth deposits have been mined in 24 states. The first discovery of fuller's earth in the United States was near Quincy, Florida, in 1893; previously it was imported from England. In 1939 mines near Quincy produced half the U.S. production.