Analysis of Iron-Bearing Clay Minerals by Electron Spectroscopy for Chemical Analysis (ESCA)

Abstract

Abstract Nontronite and biotite were analyzed by Electron Spectroscopy for Chemical Analysis (ESCA). Both minerals yielded ESCA spectra with well-defined peaks and the elements identified by the ESCA spectra were in good agreement with the molecular formulas. High resolution scans were made of the iron (2 p 3/2 ) and oxygen (1 s ) electron binding energies for oxidized and reduced forms of nontronite and biotite. Binding energies for Fe 3+ were observed at 711.8 eV in dithionite-reduced nontronite and in oxidized biotite. Peaks for Fe 2+ occurred at 710.0 eV for unaltered biotite, at 709 eV for oxidized biotite and at 708.6 eV for hydrazine-reduced and dithionite-reduced nontronite. The oxygen (1 s ) peak for unaltered nontronite was skewed to the high energy side of the 530.6 eV maximum, but became more symmetrical as the Fe 2+ content increased.