As of 1993 there is still a long term supply. However, its added whiteness and low coal and other particulates make it an attractive material. Do not breathe dust. Ball clay is a plastic, fine grained cream or white firing clay which is easily slaked in water. The term 'ball' traces to historic mining methods in England where large chunks of the clay were cut from the bank in ball shapes for transport for processing.
Ball clays tend to have very high dry shrinkage combined with high green strength and slow drying.
Were it not for the iron and coal impurities, ball clay would be an ideal ceramic material. However, in practical terms, it is used to achieve desired plasticity, but is minimized to reduce the detrimental effect it most often has on fired whiteness and drying properties. Ball clay deposits occur in formations of different age, and were laid by the action of slow moving water with an acidity that tended to floculate and settle the clay. It is common to find lignite associated with ball clay, and this accounts for the almost black appearance of many brands when they are wet. Ball clay is not a clay mineral in itself, but contains other minerals, primarily kaolinite, but also montmorillonite, halloysite, or illite.