in Islāmic (Islamic arts) ceramics, a school of Turkish pottery making that flowered throughout the 16th and on into the 17th century. There may have been potteries at İznik, 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. The chief centre of production became established in the city of İznik. Early 16th-century İznik wares were influenced by the blue-and-white porcelain of Ming-dynasty China and by Persian wares. İznik ware was soft and sandy, being of grayish-white clay covered with a thin, usually white slip (a mixture of clay and water). Flat dishes were the commonest shapes, but bowls, jugs, and flower vases were also made. They were painted with stylized and symmetrical designs of flowers, leaves, and fruits, along with abstract linear motifs based on these natural forms and others such as fish scales. By the mid-16th century the range of colours used in the decoration had expanded from blue and white to include turquoise, several shades of green, and purple and black. Red had become a frequently used colour by the late 16th century. The quality of İznik ware declined in the 17th century, and by 1800 manufacture had ceased.