Kaolinite is the principal mineral present in kaolin clays. It has a flat plate-like structure. This scanning electron microscope image of a sample of kaolinite at a magnification of 1,500 times clearly shows this.
Kaolinite’s layered structure – with tight packing between the layers like the pages of a closed book – means that kaolinite clay does not shrink when dry or swell when wet.
Image: Schlumberger, Houston Texas