also known as FRENCH BURR STONE. Imported millstones, usually built up of shaped blocks of freshwater quartz (siliceo calcareous stone) quarried in the Paris basin mainly near La Ferte sous Jouarre along the River Marne and at Epernon; set in cement or Plaster of Paris and bound with metal bands, for grinding wheat to produce flour. Introduced to England in the C15th. Generally about 4ft diameter and 1ft thick, weighing up to 18cwt. Very occasionally stones made from a single block of stone. Valued as the stone for producing white flour. Made up into millstones in numerous places in Britain.