China-clay found little use until the mid-18th century, as it was difficult to separate from the matrix of quartz sand and it lacked the natural plasticity of a good potting clay. Its main property is an exceptional resistance to heat. Refractory clays, as heat resistant types are know, were ideal for the lining of tin-smelting furnaces and there is some evidence that china-clay was being mined on Hensbarrow, for this purpose, as early as the 16th century.

The mining of china-clay for the purposes of porcelain production, however, only began in 1745 in Cornwall when the apothecary William Cookworthy discovered clay deposits at Tregonning Hill and at Carloggas. Here we would like to emphasise that William Cookworthy was not the first person to discover the existence of china-clay in Britain. However, he was the first person in Britain to make the connection between china-clay and the production of porcelain. After his discovery of the kaolin deposits, Cookworthy experimented with the manufacturing of porcelain for about 20 years unitl, in 1768, he finally managed to patent a method to turn the clay into fine porcelain. Shortly afterwards he established the Plymouth Porcelain Factory, which later moved to Bristol. Other potteries in the UK followed suite and started to use china clay, also know as kaolin, from Cornwall.  

By the early 19th century, the deposits around  St Austell had emerged as the largest in the world and the Cornish kaolin industry had become big business, with a multitude of small companies selling their products on the open market, a market that was by then rapidly expanding. Apart from china, kaolin was also used in many other products such as paper, paint and rubber goods. By 1910 production was nearly one million tons a year, 75% of which was exported  to North America or Europe. Before World War I, about 70 china clay producers were operating in Cornwall and the competition was cut throat. This often resulted in harsh working conditions for the  thousands of men which were employed in the industry.  

In 1919 the three largest china clay producers, namely the West of England China Clay Company (established 1849), Martyn Brothers (established 1849) and North Cornwall China Clays (established 1908), merged into English China Clays (EEC). At that time these three companies accounted for about 50% of the total china clay output. In 1932 ECC acquired its rivals John Lovering and HD Pochin. By the end of the 1960s ECC was producing around 2.5m tons of kaolin a year. In 1999 ECC was bought by the French company Imetal (which was founded in 1880 by the Rothschild family). Imetal was later renamed into Imerys, now a multinational company that specialises in the  production and processing of industrial minerals.