X-RAY PHOTOELECTRON STUDIES OF TITANIUM IN BIOTITE AND PHLOGOPITE

X-ray photoelectron diffraction data from single crystals of a biotite containing 1~o Ti show that although this element is located entirely in octahedral sites, the Ti sites are not precisely equivalent to those of Mg and Fe. Comparisons of Ti 2p X-ray photoelectron spectra from two biotites and from two titaniferous phlogopites ( ~0.3~0.5~ Ti) with those from Ti(II), Ti(IIl) and Ti(IV) oxides indicate that this element is present as Ti(llt) rather than Ti(IV) in all four micas.