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My first thought was it's Native American, but then I theorized it may be a river-worn fragment of early Medalta Redware.
Medalta is a jewel in the Canadian Badlands, an industrial museum and contemporary arts centre, framed by the dramatic cliffs of the South Saskatchewan River in Medicine Hat, Alberta. Set in the 150-acre Historic Clay District on the South Saskatchewan River, the Medalta Potteries factory was housed within brick and steel buildings dating from 1912 to the 1930s. After launching as the Medicine Hat Pottery Company, the enterprise changed its name to Medalta Stoneware Limited and then Medalta Potteries Limited. The “Medalta” name was taken from the name of the town (Medicine Hat) combined with the original postal designation for Alberta (Alta).
Medalta Potteries expanded its site to include four beehive kilns built using medieval designs. Locally produced bricks were carefully crafted to fit together without the use of mortar. They relied strictly on gravity to hold them up much the same way as the Inuit igloo is configured. The expansion also included five industrial buildings, a rail line, an internal road network and in-situ machinery over a 3.2-hectare property set along the Canadian Pacific Railway (CPR). From the 1920s through the 1940s, Medalta was the largest and most successful pottery business west of Toronto, providing 75 per cent of all the pottery made in Canada. Medalta closed as a pottery factory in 1954 and, after 42 years, reopened as a museum in 1998.