The river valley around St Austell once contained several clay works, and by 1858 there were 42 different companies producing a total of 65,000 tons of clay every year. China Clay is still Cornwall's largest industry but today only four companies operate pits in the area with an output of three million tons, 80% of which is used in paper.
Wheal Martyn Clay Works were established by Elias Martyn in the 1820s and became one of the major clay producers in Cornwall. When Elias died in 1872 some parts of the works were closed completely and other areas were leased out. It wasn't until 1880 that they were revived when John Lovering took over the lease, introducing new techniques and redeveloping the site to work at optimum levels. A slump in trade caused the closure of the pit in 1931, but the dry remained in use to work lower grade clay from other pits in the valley. By 1971 the Wheal Martyn China Clay works were once again operational, and the large quarry continues to be worked today producing about 2,000 tons of china clay a week - the same quantity that Elias Martyn managed in a year in 1869.
Formed from the decomposition of minerals in Granite, china clay (or Kaolin) is the fine white powder that is extracted with the use of water to give a slurry. The clay slurry was then pumped from the pit to refining channels, then into settling pits, and finally into settling tanks where it would remain for up to three months. Once the clay started to solidify it would be transferred to the kiln (dry)' and spread over pan tiles to be dried for a couple of days until it could be cut into blocks and stored.
Nearly all the work was done by hand in the early days of production, but as the pits got deeper and the quantities increased, water-wheels were used to power the pumping process, hoses replaced naturally diverted streams to wash the clay deposits from the granite, and tramways were constructed for transporting the material. Later still, steam engines were introduced, with gas later replacing the coal-burning furnaces. Today high pressure monitors, operated by remote control, wash the clay while huge dumper trucks are filled with the waste sand and rock.
In 1975 the Wheal Martyn China Clay Musuem was established, being housed in two of the old clay works. Most of the buildings and the processing equipment around the site dates from the time that Lovering took over the clay works. This is not only a unique opportunity to explore the origins of one of Cornwall's most important industries, but it also affords the visitor a chance to discover an amazing diversity of wildlife along the Nature Trail. Enjoy a picnic beside the magnificently restored 35ft (10.6m) water-wheel, follow the milky-white stream as it trickles its way across the site, or walk through the woodland and listen out for the many varieties of bird who regularly visit this area. The whole experience is both historically fascinating, and scenically beautiful.