On the x-ray determination of the iron-magnesium ratio in biotites

Abstract

On the basis of the newly acquired knowledge of the crystal structure of the trioctahedral micas a new theoretical curve is proposed which permits the x-ray determination of octahedral Mg and Fe content in biotites from the relative intensities of the 004, 005, 006 reflections. It is believed that the error in this x-ray determination is not greater than ± 0.5 atoms of Mg or Fe for six octahedral sites.