X-ray absorption study of some iron-rich micas

This is the authors' abstract. We don't add key points for this paper.

The K-absorption spectrum has been studied in the cases of muscovite, biotite and phlogopite micas, iron metal, FeSO 4 and Fe 2 O 3 with a view to demonstrating the usefulness of this technique in the study of minerals and to study their complex chemistry. The investigation has been carried out both before and after subjecting the mica samples to heat treatment around 800 degrees C and the observations interpreted in terms of the consequent chemical and structural changes. This heat treatment was found to lead to almost total conversion of Fe 2+ to Fe 3+ and distortion of the octahedra in biotite and phlogopite. Muscovite, however, shows no change in either the Fe 2+ and Fe 3+ ratio or the shape of the spectrum on heat treatment of the sample. The results are compared and found to be in very good agreement with those available from other techniques.