Compositional change of Raman spectrum of Fe-bearing brucite

Abstract

We examine compositional changes in Raman spectrum of brucite upon incorporation of Fe in order to develop a measure of Mg / (Mg + Fe) applicable to brucite in sub-micron composites in serpentinites. As the Fe content increases, Raman O-H band at 3650 cm-1 for end member brucite splits into several peaks at lower wavenumber without any compositional shifts for the O-H peaks. These O-H peaks can be separated into 2 group corresponding patterns of coordination of cations to O-H: MgMgMg and MgMgFe.