Semiquantitative Electron Microprobe Determinations of Fe^(+2)/Fe^(+3) and Mn^(+2)/Mn^(+3) in Silicates and Their Application to Petrologic Problems

Semiquantitative determinations of Fe^(+2)/Fe^(+3) and Mn^(+2)/Mn^(+3) by electron microprobe analysis have important applications to petrological and mineralogical problems. Anderson (1966) showed that the relative intensities of Fe L_α and L_β X-ray emission peaks differ with the valence states in Fe, FeS_2, Fe_2O_3, and Fe_3O_4. Such measurements were extended to FeO (synthetic wustite) and Mn oxides, but the variations in their relative intensities are not directly applicable to silicates, presumably due to structural effects, and direct calibration with silicates is necessary