Strong, high-grade ceramic ware made from a mixture of suitable clays finely ground minerals such as quartz and feldspar. After firing at high temperature the ware shall not, even when unglazed, have an average value of water absorption greater than 0.5 percent of the dry weight of the ware. It shall be coated on all exposed surfaces with an impervious non-crazing vitreous glaze giving a white or colored finish.