China clay, which finds so many industrial applications in the technical world of today, resulted in Cornwall and Devon from a sequence of events that began over 300 million years ago.

The deposits have been worked for 230 years and are unique in that they are the largest in the world. Around 120 million tons of china clay have been produced since William Cookworthy's first discovered it at Tregonning Hill in 1746, but reserves are sufficient for at least another hundred years.

The early history of the industry is naturally closely concerned with the discovery and production of china clays for use in ceramics. The story, though, starts thousands of years ago and thousands of miles away.

China, the pure white porcelain used by the Chinese, was discovered millennia ago and has always been a much-prized material. Despite many attempts to find it elsewhere, it remained elusive until a few deposits were found in parts of Europe and in America early in the eighteenth century, on which the search to find sources in Britain intensified. 

It was a Quaker apothecary-cum-potter, William Cookworthy, who at last made the discovery of clay, or kaolin, in Cornwall in 1746, and it was realised it was of a much finer quality than elsewhere in Europe.

He experimented with various samples and in 1768 took out a patent to use the material, soon producing items at his Plymouth Porcelain Factory. Until that time English pottery had consisted of coarse earthenware and stoneware ceramics and had suffered considerable competition from elsewhere.

As more potteries made use of porcelain, so the demand grew and by the early nineteenth century the kaolin industry had become highly successful, with many of the Potters owning rights to mine the material for themselves. In addition, by the middle of the nineteenth century, china clay was increasingly being used as a raw material by the developing paper industry.

Early in the twentieth century, the industry was made up of some seventy or so individual producers, each competing on price with little regard for marketing or standards. There was almost no capital investment or product development and over-production was great, wages were low and working conditions were poor.

Despite this, by 1910 production was approaching a million tons a year and paper had completely overtaken ceramics as the prime user. Over 75% of output was exported, with North America and Europe being major markets, and the china clay industry in Cornwall and Devon held a virtual monopoly on supply to the world.