TETRAHEDRAL FERRIC IRON IN PHLOGOPITE - XANES AND MOSSBAUER COMPARED TO SINGLE-CRYSTAL X-RAY DATA

This paper reports the results of a combined methodological study perf ormed on tetraferriphlogopite from the Araxa carbonatite. We compare M ossbauer spectroscopy and X-ray absorption near-edge spectroscopy (XAN ES) results to previously reported single-crystal X-ray and electron m icroprobe analysis data (Cruciani & Zanazzi, 1994). The combined techn iques provide evidence for the presence of a remarkable amount of tetr ahedrally coordinated Fe3+ in this sample, and show that high OH conte nt in tetraferriphlogopite is compatible with the large Fe2O3/FeO rati o inferred from the chemical and spectroscopic data.