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The unique mineral formulation of ball clay provides a plastic or sticky substance that civilizations have used since ancient times. Miners excavate this clay in England and certain eastern states in the United States. Ceramics and ground surface materials may contain the substance. Products may contain ball clay alone or a combination of the clay mixed with other minerals.
This fine grained, sticky clay is relatively inexpensive but is considered rare because of the geological factors required for its formation. Ball clay is composed of varying amounts of kaolin, mica, and quartz. It also usually contains other trace minerals and carbon by-products. The raw clay generally varies in color from shades of blue to beige and white, depending on the amount of kaolin and iron oxides the mixture contains. Companies that make china usually prefer the whiter variety.
Devon County in southwestern England contains the largest clay deposits in Europe. In the United States, California and many eastern states contain ball clay deposits. Tennessee and Kentucky generally have the largest deposits, which may be up to 20 acres (8 hectares) in size. The clay fields may extend 18 to 40 feet (5.4 to 12 meters) below the surface.
The British originally excavated ball clay by hand with spades. Miners cut cubes commonly measuring one cubic foot (0.028 cubic meters). Handling and transporting the clay frequently smoothed the edges of the soft substance, causing the slabs to appear more like a ball than a cube. Today, workers excavate the clay quarries with backhoes. Instead of small cubes, miners generally extract ball clay in stepped tiers.
Shredders break the material into small pieces that are roughly the size of golf balls. Ball clay providers frequently sell the clay in this high-moisture form powdered or unpowdered. The next processing step is drying and grinding the clay. China and porcelain bathroom fixture manufacturers use this processed form. The clay may further undergo slurry exposure, noodling, and combination with other ingredients.
Manufacturers create ball diamond clay by mixing the substance with fine sand. Communities generally spread and compact this product into a flat, smooth, solid surface. The clay in this form is typically used for the surface of baseball diamonds, horse stalls, and paddocks.
Ancient Romans in England were the first people to mine ball clay. During Roman times, people used the substance for creating basic pottery. The English did not mine the rich mineral substance again until the middle of the 15th century. Sir Walter Raleigh popularized smoking tobacco, and the clay was used in pipe manufacturing because of the material's sticky, but sturdy properties.