in ceramics, a school of Turkish pottery making that flowered throughout the 16th and on into the 17th century. .... clai potteri

There may have been potteries at Iznik, where there were deposits of suitable clay, as early as the 12th century, but it was not until the late 15th century that pottery making came into its own in Turkey. Iznik ware was soft and sandy, being of grayish-white clay covered with a thin, usually white slip (a mixture of clay and water).