Home Kaolinite, kaolin

Crystal lattice of kaolinite
Fig. 1. Crystal lattice of kaolinite 
Formula Al2[(OH)2|Si2O5]
Density  2.1-2.6 g/cm3
Hardness 1
CAS-No. 1318-74-7

Kaolin is a clay mineral consisting of the mineral kaolinite (cf. chemical data) with admixtures of quartz and feldspar. Kaolin indicates a grain size of 0.2-1µm, which is clearly in the colloidal range. Kaolin is used as a high temperature bonding agent in ceramics as well as a constituent in coatings. At temperatures >1500°C kaolin is converted into mullite. Further it is a filler in the paper industry. The more rarely occuring minerals dickite and nakrit have the same chemical formula as kaolinite, however they differ in the type of stacking the Al2[(OH)2|Si2O5] -layers.

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© 2004 Büro für angewandte Mineralogie · Dr. Stephan Rudolph · D-47918 Tönisvorst
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