Ball clay

Ball clays are kaolinitic sedimentary clays that commonly consist of 20–80% kaolinite, 10–25% mica and 6–65% quartz, along with small amounts of organic matter (such as lignite) and trace amounts of other minerals such as pyrite and siderite.

They are a common raw material for various types of ceramics, where their primary roles are to impart unfired strength, plasticity or to aid rheological stability during the shaping processes.^[1] Most ball clays impart colours ranging from buff to cream to off-white when fired in an oxidising atmosphere.^[2][3]

The name "ball clay" is derived from the form of the extracted material when dug by spade as cubes, which then became rounded during subsequent transport, in Dorset and Devon, England during the early days of the industry during the 18th century.^[4][3]

In 2008, UK production of ball clay was reported to be worth £82 million, with sanitaryware manufacturers being the largest single group of end users, representing 40% by volume.^[5]