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'Purbeck Ball Clay' is a concentration of ball clay to be found on the Isle of Purbeck in the English county of Dorset.

Contents

Geology

Exploitation

References

External links

Geology

Ball clay is an extremely rare mineral found in very few places around the world, and the Purbeck blue clays of the Bagshot Beds found around Wareham are of the finest in the world. The main concentration of ball clay in Dorset is to the north of the Purbeck Hills centred around Norden. Ball clays are sedimentary in origin. Approximately 45 million years ago (in the Lutetian stage of the Eocene epoch) the climate was tropical and an ancient river Solent washed kaolinite (formed from decomposed granite) from its parent rock on Dartmoor. As the streams flowed from upland areas they mixed with other clay minerals, sands, gravels, and vegetation before settling in low-lying basins to form overlaying seams of ball clay. Ball clays usually contain three dominant minerals: from 20-80% kaolinite, 10-25% mica, and 6-65% [quartz]. In addition, there are other 'accessory' minerals and some carbonaceous material (derived from ancient plants) present.

Exploitation

Purbeck ball clay has been used for thousands of years, but large scale commercial extraction began in the middle of the 18th century continuing to the present day. The principal ball clay workings were in the area between Corfe Castle and Wareham. Originally the clay was taken by pack horse to wharves on the River Frome and the south side of Poole Harbour. The Railways of Purbeck, , R.W., Kidner, The Oakwood Press, 2000,
Large quantities were ordered by Josiah Wedgwood from 1771 and this led to the construction of Dorset's first railway in 1806. This was the Middlebere Plateway, which connected clay workings owned by clay entrepreneur Benjamin Fayle in the Corfe Castle area, to a wharf on Middlebere Creek in Poole Harbour. Other similar tramways followed, including the Furzebrook Railway (1830), the Newton Tramway (c.1860), and Fayle's Tramway (1907). With the coming of the London and South Western Railway line from Wareham to Swanage in 1885, much ball clay was dispatched by rail. The Railways of Purbeck, , R.W., Kidner, The Oakwood Press, 2000,
Approximately 80% of the ball clay extracted has been exported all around the world. The ball clay is processed today at the Furzebrook plant of Imerys.
It is said that 1/3 of all fine pottery ever produced in England contains Purbeck Ball Clay.
Ball clays are used in making everday articles including -
:for the home wall and floor tiles, wash basins, toilet bowls, plates, cups and saucers, linoleum, acoustic ceiling tiles, insulated electrical cables, pale coloured bricks, and clay drainage pipes;
:for the car: windscreen wipers, spark plugs, and engine mountings;
:for the Garden: hoses and fertilisers;
and other uses: pharmaceutical and polymers and many others.

References

External links

★ Geology of the Wessex Coast

★ Purbeck Mineral & Mining Museum