The china clay deposits in Cornwall are the largest in the world and have been worked since William Cookworthy first discovered it at Tregonning Hill in 1746. 120 million tons of china clay have been extracted, but reserves in the ground will last at least another hundred years.
China clay was used over one thousand years ago by the Chinese to make a pure white porcelain. A few deposits were found in parts of Europe and in America early in the eighteenth century. But nothing of note in Britain until a Quaker apothecary-cum-potter, William Cookworthy, discovered this clay, or kaolin, in Cornwall in 1746, and it was of a much finer quality than elsewhere in Europe.
By 1768 he had patented a way to use the clay and developed a his own Plymouth Porcelain Factory. English pottery had previously been of coarse earthenware and stoneware, now the gentry could get white porcelain. .
Other potteries started to use china clay from Cornwall, and by the early nineteenth century the kaolin industry had become a big business. Many of the pottery factories owned rights to mine the material themselves. In addition to pottery, kaolin was starting to be used as a whitner by the paper industry.
Early in the twentieth century there were around seventy producers. The competition was cut-throat. Corners were cut, with little capital investment, product development, wages were low, working conditions were poor.
By 1910 production was nearly one million tons a year and paper was using more than ceramics. 75% of output was exported mainly to North America and Europe. Cornwall held a virtual monopoly on world supply.
The three largest producers joined amalgamated in 1919, forming English China Clays Limited. They had 50% of the industry's capacity. ECC became the leading clay producing company for the rest of the century.
English China Clays was acquired by Imetal of France for £756m in 1999. It continued to be run as ECC.
You can learn about it at the Wheal Martyn China Clay Museum . And the chemistry of China Clay . The story of Wheal Grey tells of its change from tin to clay, and eventual closure.
Today around 80% of the china clay produced is used in paper. Of the rest, 12% is used by the ceramics industry and the balance in products such as paint, rubber, plastics, cosmetics, pharmaceuticals, cork and agricultural products.
Clay from Cornwall and Devon: An Illustrated Account of the Modern China
Clay: Traditional Mining Methods in Cornwall
China Clay Heritage (Cornwall's Heritage S.)
John R. Smith
Mines and Mining in Cornwall