What is Kaolin or China Clay? What is Kaolinite? What is the chemical formula of China Clay or Kaolin?

The name Kaolin has been derived from the Chinese word Kao-ling, which means high ridge and also it is the name of a hill near Jauchu Fu, from where the used for making porcelain, was obtained by the ancient Chinese people. The term is now generally applied to those residual clays usually white in colour and derived from rocks composed entirely of feldspar or another similar minerals, containing no or very little amount of iron oxide. These clays contain a high percentage of the mineral kaolinite together with other hydrous alumino-silicates. In England the term china clay is applied to the white plastic clays derived from washing the decomposed Cornish or Dovonain granite. But for all practical purposes Kaolin or China clay may be taken as identical containing approximately 46% silica (SiO₂), 40% alumina (Al₂O₃), and 14% water (H₂O) and corresponding to the formula Al₂O₃.2SiO₂.2H₂O.

Click on the image for the best view