Minerals (Category A)
Kaolin, or China clay, is nearly white in color. It is distinguished from other industrial clays based on its fine particle size and pure coloring. Its ability to disperse in water make it an ideal pigment.
The primary constituent in kaolin is the mineral kaolinite, a hydrous aluminum silicate formed by the decomposition of minerals such as feldspar.
The name kaolin derives from the Chinese and means high ridge. High ridge is a reference to the hill in south-eastern China where the clay was originally discovered and used. In the 7th and 8th centuries, the Chinese were the first to use kaolin to make porcelain. It was not until centuries later that other areas of the world could duplicate the process.
The white color of the mineral can either be naturally occurring, or can result after processing which removes minerals and other color-bearing compounds. The small particle size of the mineral contributes to its white color by scattering light.
Although kaolin is found throughout the world, deposits with suitable whiteness, viscosity and other favorable characteristics are rare. Ironically, the best deposits are not located in China. The Unites States has high-quality deposits in the Southeast. The mineral has been mined since colonial times in Georgia and South Carolina. Other valuable deposits are located in Brazil and the United Kingdom.