Kaolinite is a hydrous silicate of aluminium with the formulae Al2Si2O5(OH)4 and a relative hardness of 3. It has a crumbly habit and forms the basis of most clay. Kaolinite is derived from the decomposition of feldspars, particularly aluminiumsilicates and is one of the most important of the natural industrial substances, used for bricks, ceramics, and many other applications. Research Kaolinite