Lack of replacement of aluminium in kaolin minerals by magnesium or iron is an extremely important factor in the formation of soil. Aluminium in muscovite can be replaced by magnesium and iron forming phlo-gopite and biotite. The iron present in micas and other ferro-magnesian minerals is expelled as oxides or hydrous oxides when weathering to kaolin takes place. Montmorillonite, nontronite and related minerals, on the other hand, which are more closely similar to micas than are the kaolin minerals, can retain iron as weathering proceeds.

This content is PDF only. Please click on the PDF icon to access.

First Page Preview

First page PDF preview
You do not have access to this content, please speak to your institutional administrator if you feel you should have access.