China clay first came into existence in Cornwall as the result of events that began over 300 million years ago. The deposits, which have been worked for some 230 years, are unique in that they are the largest in the world. Although some 120 million tons of clay have been mined since 1746, when William Cookworthy discovered clay at Tregonning Hill near Helston, there are said to be sufficient reserves to last for at least another 100 years. The Wheal Martyn museum is located a few miles north of St Austell in the area where the greatest amount of china clay can be found on the St Austell moors. The clay occurs in deposits in the form of china clay rock, a mixture of up to 15 per cent china clay and up to 10 per cent mica, and the remainder being quartz. Today china clay has taken over the position as Cornwall's most important extractive industry. The value of clay sold to date, at today's prices, is £13.5 billion, compared with the value of tin and copper sold at £9 billion.

Wheal Martyn Clay Works were founded by Elias Martyn in the 1820s and became one of the major clay producers in Cornwall. Since 1975 the Wheal Martyn China Clay Musuem has occupied part of the site which still produces china clay to this day. Water-wheels were used to operate pumps, although later many were replaced by steam engines. Wheal Martyn's 35ft water-wheel was originally used to pump clay slurry from the pit. The museum at present is undergoing a £1 million re-development funded mainly by the Heritage Lottery Fund and Objective One, it's planned to open the re-developed area in June.                                                                                                            Photo: David Packman

Sand and Mica Drags are concrete channels used to settle out the finer quartz sand from the slurry. Every two hours the drain plugs were removed and the sand drags scraped clean. The slurry now containing only very fine china clay particles, fine sand and flakes of mica enters a series of wooden channels called mica drags. Flowing slowly it drops the mica on to the floor of the channels while the fine clay flows on, the mica was cleared every eight hours and washed to the river.

Photo: David Packman

Settling Pits were large granite tanks with a sloping floor holding about 250 tons of clay slurry. The clay was allowed to settle over a period of days and the water progressively run off until the clay had the consistency of single cream, a plug was then lifted and the clay passed on to the pan kiln.                                                                Photo: David Packman

Once inside the Pan Kiln the clay was spread across the floor of the kiln and dryed. Under the floor are a series of horizontal flues from the coal fired furnaces to the chimney, the floor being made of porous pan tiles allowed the heat through to dry the clay.                                                                                                             Photo: David Packman

The Incline tram road was used to transport waste material from the pit to a spoil tip on the surface. The bottom of an incline, known as a dog's hole is reconstructed above.                   Photo: David Packman

Photo: David Packman

                                                                                                                     Photo: David Packman

A water monitor which was used to wash the clay face at a pressure of
300 lbs per square inch.                                       Photo: David Packman

The pit viewing area overlooks two small working pits, Greensplat and Wheal Martyn. Click on the image for a larger view

Photo: David Packman