Purbeck Ball Clay
Encyclopedia
Purbeck Ball Clay is a concentration of ball clay
found on the Isle of Purbeck
in the English
county of Dorset
.
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.
. Originally the clay was taken by pack horse to wharves
on the River Frome
and the south side of Poole Harbour
.
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 the London Merchant Benjamin Fayle in the Corfe Castle area, to a wharf on Middlebere Creek in Poole Harbour. Other similar tramways followed, including the Furzebrook Railway
(c.1840), the Newton Tramway (1854), 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.
Approximately 80% of the ball clay extracted has been exported. The ball clay is processed today at the Furzebrook plant of Imerys
. It is said that a third of all fine pottery ever produced in England contains Purbeck Ball Clay.
Ball Clay has been very important in the way our living standards have developed. Without the porcelain insulators from which overhead cables are suspended, there could be no high-tension electricicity distribution grid. Without porcelain insulators the spark plug and the internal combustion engine may not have existed. Without the far-from-romantic products of the vitreous china saniteryware industry, modern sanitation would have been impossible, Without Ball Clays to bind refractory materials, a whole host of metallurigical and engineering processes could not be carried out. Without powdered clay, many forms of animal food - and hence milk and meat and eggs in the past- would have been more expensive, and many types of fertiliser would have been difficult if not impossible to spread satifactorily on agricultural land. The list of uses for Ball Clays is surprisingly long, and many are not ceramic applications at all.
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 minerals and carbonaceous materials such as lignite...
found on the Isle of Purbeck
Isle of Purbeck
The Isle of Purbeck, not a true island but a peninsula, is in the county of Dorset, England. It is bordered by 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 north. Its western boundary is less well...
in the English
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
county of Dorset
Dorset
Dorset , is a county in South West England on the English Channel coast. The county town is Dorchester which is situated in the south. The Hampshire towns of Bournemouth and Christchurch joined the county with the reorganisation of local government in 1974...
.
Geology
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 LutetianLutetian
The Lutetian is, in the geologic timescale, a stage or age in the Eocene. It spans the time between and . The Lutetian is preceded by the Ypresian and is followed by the Bartonian. Together with the Bartonian it is sometimes referred to as the Middle Eocene subepoch...
stage of the Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
epoch) the climate was tropical and an ancient River Solent washed kaolinite
Kaolinite
Kaolinite is a clay mineral, part of the group of industrial minerals, with the chemical composition Al2Si2O54. It is a layered silicate mineral, with one tetrahedral sheet linked through oxygen atoms to one octahedral sheet of alumina octahedra...
(formed from decomposed granite
Granite
Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...
) from its parent rock on Dartmoor
Dartmoor
Dartmoor is an area of moorland in south Devon, England. Protected by National Park status, it covers .The granite upland dates from the Carboniferous period of geological history. The moorland is capped with many exposed granite hilltops known as tors, providing habitats for Dartmoor wildlife. The...
. 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
Kaolinite
Kaolinite is a clay mineral, part of the group of industrial minerals, with the chemical composition Al2Si2O54. It is a layered silicate mineral, with one tetrahedral sheet linked through oxygen atoms to one octahedral sheet of alumina octahedra...
, 10-25% mica
Mica
The mica group of sheet silicate minerals includes several closely related materials having highly perfect basal cleavage. All are monoclinic, with a tendency towards pseudohexagonal crystals, and are similar in chemical composition...
, and 6-65% quartz
Quartz
Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of 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 and continues today. The principal workings were in the area between Corfe Castle and WarehamWareham, Dorset
Wareham is an historic market town and, under the name Wareham Town, a civil parish, in the English county of Dorset. The town is situated on the River Frome eight miles southwest of Poole.-Situation and geography:...
. Originally the clay was taken by pack horse to wharves
Wharf
A wharf or quay is a structure on the shore of a harbor where ships may dock to load and unload cargo or passengers.Such a structure includes one or more berths , and may also include piers, warehouses, or other facilities necessary for handling the ships.A wharf commonly comprises a fixed...
on the River Frome
River Frome, Dorset
The River Frome is a river in Dorset in the south of England. At 30 miles long it is the major chalkstream in southwest England. It is navigable upstream from Poole Harbour as far as the town of Wareham.-Geography:...
and the south side of Poole Harbour
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 formed at the end of the last ice age and is the estuary of several rivers, the largest being the Frome. The harbour has a long history of human settlement...
.
Large quantities were ordered by Josiah Wedgwood
Josiah Wedgwood
Josiah Wedgwood was an English potter, founder of the Wedgwood company, credited with the industrialization of the manufacture of pottery. A prominent abolitionist, Wedgwood is remembered for his "Am I Not A Man And A Brother?" anti-slavery medallion. He was a member of the Darwin–Wedgwood family...
from 1771 and this led to the construction of Dorset's first railway in 1806. This was the Middlebere Plateway
Middlebere Plateway
The Middlebere Plateway, or Middlebere Tramway, was a horse-drawn plateway on the Isle of Purbeck in the English county of Dorset. One of the first railways in southern England and the first in Dorset, the plateway was built by a very wealthy London Merchant Benjamin Fayle , to take Purbeck Ball...
, which connected clay workings owned by the London Merchant Benjamin Fayle in the Corfe Castle area, to a wharf on Middlebere Creek in Poole Harbour. Other similar tramways followed, including the Furzebrook Railway
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...
(c.1840), the Newton Tramway (1854), and Fayle's Tramway (1907). With the coming of the London and South Western Railway
London and South Western Railway
The London and South Western Railway was a railway company in England from 1838 to 1922. Its network extended from London to Plymouth via Salisbury and Exeter, with branches to Ilfracombe and Padstow and via Southampton to Bournemouth and Weymouth. It also had many routes connecting towns in...
line from Wareham to Swanage
Swanage
Swanage is a coastal town and civil parish in the south east of Dorset, England. It is situated at the eastern end of the Isle of Purbeck, approximately 10 km south of Poole and 40 km east of Dorchester. The parish has a population of 10,124 . Nearby are Ballard Down and Old Harry Rocks,...
in 1885, much 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 plant of Imerys
Imerys
Imerys is a French multinational company. It is a constituent of the CAC Mid 60 index.-History:The Company was founded in 1880 and for many years was known as Imetal....
. 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, spark plugs, and engine mountings
- hoses and fertilisers
- pharmaceutical and polymers and many others
Ball Clay has been very important in the way our living standards have developed. Without the porcelain insulators from which overhead cables are suspended, there could be no high-tension electricicity distribution grid. Without porcelain insulators the spark plug and the internal combustion engine may not have existed. Without the far-from-romantic products of the vitreous china saniteryware industry, modern sanitation would have been impossible, Without Ball Clays to bind refractory materials, a whole host of metallurigical and engineering processes could not be carried out. Without powdered clay, many forms of animal food - and hence milk and meat and eggs in the past- would have been more expensive, and many types of fertiliser would have been difficult if not impossible to spread satifactorily on agricultural land. The list of uses for Ball Clays is surprisingly long, and many are not ceramic applications at all.