tortoiseshell ware

tortoiseshell ware, earthenware with variegated, surface colour made in Staffordshire, England, in the 18th century. It was a subdivision of the “clouded” (agate) ware made about 1755–60 at Staffordshire, especially by Thomas Whieldon. The brown colour of the tortoiseshell ware is derived from manganese oxide. The different clouded effects were obtained by treating the lead glaze with different oxides; only that with brown mottling is properly called “tortoiseshell,” though the term is often used loosely to include multicoloured clouded ware in general.