a very adhesive, plastic clay; spec. a fine-textured kaolinitic clay, found in south-western England and in other parts of the world, which is used in the manufacture of earthenware
Ball clays are fine-grained kaolinitic sedimentary clays, that commonly consist of 20-80 % kaolinite, 10-25 % mica, 6-65 % quartz. They are used in the production of ceramics to impart plasticity and unfired strength.
The contamination of kaolin found in Germany could in fact also concern other additives authorised for use as binders, anti-caking agents and coagulants under Directive 70/524/EEC, as indicated by the fact that ball clay, sedimentary clays containing other minerals besides kaolin, originating from a mine in the United States has also been shown to be heavily naturally contaminated by dioxins of geological origin.
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Ball clays were originally cut into cubes but by the time they had been hauled from Bovey Tracey, Devon, UK, to Stoke-on-Trent where they were to be used, the cubes had been turned into balls as they jostled together in barges and carts, hence the name.
