pipestone, hard, dull red or mottled pink-and-white clay stone, carved by Native Americans into pipes. Called calumets (see calumet) the pipes were used extensively in ceremonials. Native Americans held pipestone sacred, and even in time of war the quarries were regarded as neutral ground. Pipestone is sometimes called catlinite, for the artist and author George Catlin, who lived among the Native Americans. It is found mainly in Minnesota, in the Dakotas, and in Canada. Pipestone, Minn., and the Pipestone River in Manitoba, Canada, are named after the stone.