Geoscience Reference
In-Depth Information
Fig. 5.7
The scheme and model of kaolinite
double layers residing exactly on top of each other are suffi ciently thick to render
them impermeable to electron radiation.
Kaolinite does not swell when wetted by an excess of water because water mol-
ecules cannot penetrate between its double layers and are only adsorbed on its out-
side crystal surfaces. Therefore, whenever moist kaolinite is dried or even baked in
an oven, it never shrinks. Owing to this property, kaolin - the clay containing
kaolinite - is used in the porcelain industry. The stability of kaolinite is also
attributed to the fact that ions cannot enter between its 1:1 double layers. Its stability
is even further guaranteed by its nearly neutral electrical surface charge density
attributed to the very small number of free negative charges that can only exist when
