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Ball clay
From Wikipedia, the free encyclopedia
Ball clays are kaolinitic sedimentary clays, that commonly consists of 20-80% kaolinite, 10-25% mica, 6-65% quartz. Localized seams in the same deposit have variations in composition, including the content of the amount majoyr minerals, accessory minerals and the carbonaceous materials such as lignite. They are fine-grained and plastic in nature.
Ball clays are mined in many areas of the world including parts of the Eastern United States and Dorset & Devon in the United Kingdom.[1] Together with other materials they are common raw materials for many ceramic articles, where their primary roles is to either to impart plasticity or to aid rheological stability during the shaping processes.
The name "ball clay" is believed to have originated because when the clay was mined by hand, it was cut into 15 to 17-kilogram cubes. During transport the corners of the cubes rounded off leaving "balls".[2]
The ceramic use of ball clays in Britain dates back to at least the Roman era. More recent trade began when a clay was needed to construct tobacco pipes in the 16th - 17th century.[3] In 1771 when Josiah Wedgwood was known to have purchased 1400 tons of ball clay enabling him to fire thinner walled ceramics.[4]
Ball clay and the Stover Canal