The Carbis Bay Hotel. Luxury hotel near St.Ives, Cornwall

Cornwall Gardens Holiday

Enjoy a relaxing luxury holiday at the award winning Carbis Bay Hotel, while visiting some of Cornwalls most enchanting gardens with experienced Garden's host Martin G Catford, M.I.Hart.,F.I.L.A.M.,D.H.W.(Hons).

China Clay is decomposed granite, known locally as Kilas. To be precise, it is granite where the feldspar crystals have changed to kaolin, a fine white clay, leaving the quartz and mica in the rock unchanged. This process happened long ago in geological time, and affected only certain parts of the granite uplands in Devon and Cornwall.

China Clay pits contain a proportion of granite which has not decomposed, as well as veins of other minerals such as tourmaline and quartz which are too hard to be broken up and transported by water. This rocky material known as 'stent', had to be removed from working faces before the hosing of the softer material from the quarry face could continue. The resultant slurry flowed down channels and into settling tanks - the finest grade material reaching the furthest settling tank.

China Clay's main property is an exceptional resistance to heat. In China, kaolin had been used since A.D. 700 to create a particularly fine type of pottery porcelain. The manufacture of this hard ware requires the use of not only china clay or kaolin, but also the addition in exact proportions of ground china stone. It was fired in extremely high temperatures to make exceptionally strong china.

The discovery of the huge reserves of china clay and stone in Cornwall was made by William Cookworthy around 1746 (British Rail named a Class 37 diesel locomotive after him in 1983). Cookworthy, who lived between 1705-1780 was a Quaker, and a Chemist by profession. He was born in Kingsbridge in Devon, and had a wholesale chemist in Plymouth. Now, Cookworthy came to fame for first discovering the recognition of the uses of china clay could be put to - i.e. its potential for the manufacture of porcelain, etc. In fact, china stone had been quarried since Tudor times for use as a building material. After 1774, the Potters of Staffordshire, led by Josiah Wedgewood then took a great interest in Cornish clay and stone.

China Clay is mined from pits such as the one at the Eden Project. It is also found at Western Dartmoor, Bodmin Moor, the Hensbarrow Moors north of St. Austell, Tregonning Hill, West Penwith (near Penzance), and Redhill in Surrey. The clay found little use until the middle of the 18th century because it was thought to be too difficult to separate from the matrix of quartz sand. However, today it has many uses, and they say that nobody in the world is more than a few feet away from a piece of Cornwall!

China clay is therefore used in/as:
A filler / gloss in paper = 30% of weight of a quality magazine paper
Coloured pencils
Fine porcelain, Spode and Wedgewood China
Polo Mints
Rennies Extra Strong tablets
Toothpaste
False Teeth
Cosmetics and Face Creams
Water purification tablets
Desalination plants
As a filter in the manufacture of pharmaceuticals
Kaolin and Morphine medicine
Paint
As a carrier in fertilizers
Rubber products - i.e. bath mats, hot water bottles, etc
As a constituent of electrical cable insulation
Car tyres and brake pads
Car interiors (plastic panels)

The China Clay District was sometimes referred to as the Cornish Alps, because of the proliferation of inclined tips. Largely composed of white quartz sand, which can look very much like snow when seen from a distance - particularly in the evening sunshine when viewed from the west. A number of tips resulted from the many small companies working independently. It is said that no worker in a China Clay pit ever suffered an upset stomach.