Saint Austell (sŭnt ôˈstəl;) [key], town (1991 pop. 36,639), Cornwall, SW England, at the mouth of the Fowey River on St. Austell Bay. China clay (discovered there c.1755) is produced and exported, and tourism and fishing are important. The Eden Project has indoor and outdoor horticultural displays. Neighboring Fowey was a significant port in the 14th cent. The Haven was the residence of the writer Arthur Quiller-Couch. Nearby at Pridmouth are fossils and minerals of geological interest. Castle Dore, to the north, is believed to be the castle of King Mark of Cornwall and thus is associated with the story of Tristram and Isolde.