Backscattering Mössbauer MIMOS II and XRF studies on tektites from different strewn fields

Room temperature 57Fe Mossbauer spectroscopy has been used to obtain information on the redox and coordination of iron in tektites. A MIMOS II spectrometer in backscattering geometry has been used in the study, so that no sample preparation at all was required. X-ray fluorescence has been used to determine the composition of the tektites. Mossbauer spectra have been deconvoluted using three extended Voigt-based profiles to allow quantitative analysis of iron atoms valence and coordination. In all tektites, the Fe\(^{2+ }\)sites have been distinguished in Fe with octahedral and tetrahedral coordination. The Fe\(^{2+}\)octahedral sites show a region of isomer shift (IS) and quadrupole splitting (QS), IS \(=\) 1.02–1.14 mm/s and QS \(=\) 1.82–2.12 mm/s, relative to \(\alpha \)-Fe. The Fe\(^{2+ }\)tetrahedral sites show a region of hyperfine parameters of IS = 0.59–0.89 mm/s and QS = 1.14–1.60 mm/s. The Fe3+sites show IS = 0.11–0.33 mm/s and QS = 0.02–0.04 mm/s. The Fe3+/Fe2+ ratio was found to be 0.025–0.149.