Purbeck Ball Clay is a concentration of

ball clay Ball clays are kaolinitic sedimentary clays that commonly consist of 20–80% kaolinite, 10–25% mica, 6–65% quartz. Localized seams in the same deposit have variations in composition, including the quantity of the major minerals, accessory ...

found on the

Isle of Purbeck The Isle of Purbeck is a peninsula in Dorset, England. It is bordered by water on three sides: the English Channel to the south and east, where steep cliffs fall to the sea; and by the marshy lands of the River Frome and Poole Harbour to the n ...

in the

English English usually refers to: * English language * English people English may also refer to: Peoples, culture, and language * ''English'', an adjective for something of, from, or related to England ** English national ide ...

county of

Dorset Dorset ( ; archaically: Dorsetshire , ) is a county in South West England on the English Channel coast. The ceremonial county comprises the unitary authority areas of Bournemouth, Christchurch and Poole and Dorset (unitary authority), Dors ...

Geology

The main concentration of ball clay in Dorset is to the north of the Purbeck Hills centred on Norden. Ball clays are sedimentary in origin. Approximately 45 million years ago (in the

Lutetian The Lutetian is, in the geologic timescale, a stage or age in the Eocene. It spans the time between . The Lutetian is preceded by the Ypresian and is followed by the Bartonian. Together with the Bartonian it is sometimes referred to as the Midd ...

stage of the

Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...

epoch) the climate was

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

and an ancient

River Solent The River Solent is a now-extinct river which during the Paleocene would have flowed around the area which is now the coastlines of Hampshire and the Isle of Wight. History The River Solent was one of three major rivers in central and southern E ...

washed

kaolinite Kaolinite ( ) is a clay mineral, with the chemical composition Al2 Si2 O5( OH)4. It is an important industrial mineral. It is a layered silicate mineral, with one tetrahedral sheet of silica () linked through oxygen atoms to one octahedral ...

(formed from decomposed

granite Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies undergro ...

) from its parent rock on

Dartmoor Dartmoor is an upland area in southern Devon, England. The moorland and surrounding land has been protected by National Park status since 1951. Dartmoor National Park covers . The granite which forms the uplands dates from the Carboniferous ...

. 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%

, 10–25%

mica Micas ( ) are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into extremely thin elastic plates. This characteristic is described as perfect basal cleavage. Mica is ...

, and 6–65%

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical form ...

. 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 and continues today. The principal workings were in the area between

Corfe Castle Corfe Castle is a fortification standing above the village of the same name on the Isle of Purbeck peninsula in the English county of Dorset. Built by William the Conqueror, the castle dates to the 11th century and commands a gap in the P ...

and Wareham. Originally the clay was taken by

pack horse Pack or packs may refer to: Places * Pack, Austria, a municipality in Styria, Austria * Pack, Missouri * Chefornak Airport, Alaska, by ICAO airport code Groups of animals or people * Pack (canine), family structure of wild animals of the b ...

wharves A wharf, quay (, also ), staith, or staithe is a structure on the shore of a harbour or on the bank of a river or canal where ships may dock to load and unload cargo or passengers. Such a structure includes one or more berths (mooring location ...

on the River Frome and the south side of

Poole Harbour Poole Harbour is a large natural harbour in Dorset, southern England, with the town of Poole on its shores. The harbour is a drowned valley (ria) formed at the end of the last ice age and is the estuary of several rivers, the largest being th ...

. Large quantities were ordered by

Josiah Wedgwood Josiah Wedgwood (12 July 1730 – 3 January 1795) was an English potter, entrepreneur and abolitionist. Founding the Wedgwood company in 1759, he developed improved pottery bodies by systematic experimentation, and was the leader in the indust ...

from 1771 and this led to the construction of Dorset's first railway in 1806. This was the

Middlebere Plateway The Middlebere Plateway, or Middlebere Tramway, was a horse-drawn plateway on the Isle of Purbeck in the England, English county of Dorset. One of the first railways in southern England and the first in Dorset, the plateway was built by Benjami ...

owned by B.Fayle & Co (Directors were Alexander Jaffray, Benjamin Fayle, Richard Jaffray, J.B. Hooper and Richard Chambers). The Plateway connected clay workings in the Corfe Castle area, to a wharf on Middlebere Creek in Poole Harbour. Other similar tramways followed, including the

Furzebrook Railway The Furzebrook Railway, also known as the Pike Brothers' Tramway, was a narrow gauge industrial railway on the Isle of Purbeck in the English county of Dorset. It was built by the Pike Brothers, to take Purbeck Ball Clay from their clay p ...

(c.1840), the

Newton Tramway The Purbeck Mineral and Mining Museum exists to preserve and interpret the historic extractive industries in ball clay mining in the Isle of Purbeck. The museum is located adjacent to Norden station on the Swanage Railway and is open from the e ...

(1854), and

Fayle's Tramway The Purbeck Mineral and Mining Museum exists to preserve and interpret the historic extractive industries in ball clay mining in the Isle of Purbeck. The museum is located adjacent to Norden station on the Swanage Railway and is open from the e ...

(1907). With the coming of the

London and South Western Railway The London and South Western Railway (LSWR, sometimes written L&SWR) was a railway company in England from 1838 to 1922. Originating as the London and Southampton Railway, its network extended to Dorchester and Weymouth, to Salisbury, Exeter ...

line from Wareham to

Swanage Swanage () is a coastal town and civil parish in the south east of Dorset, England. It is at the eastern end of the Isle of Purbeck and one of its two towns, approximately south of Poole and east of Dorchester. In the 2011 census the civil ...

in 1885, much of the ball clay was dispatched by rail. Approximately 80% of the ball clay extracted has been exported. The ball clay is processed today at the

Furzebrook Furzebrook is a small village on the Isle of Purbeck, in the county of Dorset in the south of England. It is about south of Wareham and northwest of Corfe Castle, and is in the civil parish of Church Knowle. The name Furzebrook derives from t ...

plant of

Imerys Imerys S.A. is a French multinational company which specialises in the production and processing of industrial minerals. It is headquartered in Paris and is a constituent of the CAC Mid 60 index. Imerys has operations in over 40 countries and ...

. It is said that a third of all fine pottery ever produced in England contains Purbeck Ball Clay.

Usage

Ball clays are used in making everyday articles including: *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 *windscreen wipers{{citation needed, date=November 2014, spark plugs, and engine mountings *hoses and fertilisers *pharmaceutical and polymers and many others *

kiln furniture Kiln furniture are devices and implements inside furnaces used during the heating of manufactured individual pieces, such as pottery or other ceramic or metal components. Materials Commonly used materials are cordierite (up to 1275 °C), mull ...

Museum

The

Purbeck Mineral and Mining Museum The Purbeck Mineral and Mining Museum exists to preserve and interpret the historic extractive industries in ball clay mining in the Isle of Purbeck. The museum is located adjacent to Norden station on the Swanage Railway and is open from the e ...

displays an exhibition about ball clays, mining and the associated narrow gauge railways.

References

External links

Geology of the Wessex CoastPurbeck Ball Clay MerchantsPurbeck Mineral and Mining Museum
Isle of Purbeck English pottery