57Fe Mossbauer spectroscopy of tektites

Tektite glasses are investigated using Fe-57 Mossbauer spectroscopy. Room temperature spectra analysis is performed using two complementary analytical methods based on two-dimensional distributions of both isomer shift and quadrupole splitting. No a priori correlation between the two hyperfine parameters is considered. The first method, based on a shape independent distribution, provides the justification for the Gaussian distribution shape used in the second method. No ferric iron contribution is evidenced by Mossbauer spectra analysis in these samples, although several criteria are used. Ferrous iron sites are shown to be continuously distributed between four- and five-fold coordinated sites.