Kaolin is the pure form of soil (hydrated aluminum silicate) with three distinct forms of kaolinite, nacrite and dickite; all with the same chemical formula. Kaolin is found in soil masses with dark luster. Kaolin structure includes a two-layer sheet consisted of a tetrahedral silicon sheet (with hydroxyl ions) and an octahedral aluminum sheet. Aluminum ions are in the same rows with oxygen and hydroxyl ions in the tetrahedral sheet on one side and hydroxyl ions on the other side. There is a very weak bond between adjacent sheets. There are hydrogen bonds between hydroxyl ions on a sheet with oxygen ions on the adjacent sheet. Kaolin lose water and is refracted at high temperatures.