Kaolin is a hydrated aluminum silicate crystalline mineral (kaolinite, Al 2 (Si 2 O 5 ) (OH) 4 ). It was termed 'China clay' from its use in China, formed commonly from weathered granite or hydrothermal activity. It is typical of three main geological environments: (1) weathering profiles; (2) hydrothermal alterations; and (3) sedimentary ...