Mössbauer study of glasses in meteorites: The D’Orbigny angrite and Cachari eucrite

Y. A. ABDU; S. J. STEWART; I. SOUZA-AZEVEDO; A. LOPEZ; M. E. VARELA; C. KURAT; R. B. SCORZELLI

HYPERFINE INTERACTIONS

Springer Netherlands

Año: 2006 p. 1 - 1

0304-3843

Mössbauer spectroscopy measurements at room temperature (RT) and at liquid helium temperature (4.2 K) were carried out on bulk and glass samples from the D’Orbigny (angrite) and Cachari (eucrite) meteorites. The RT Mo¨ ssbauer spectrum of the bulk sample of D’Orbigny shows the presence of Fe2+ in olivine and pyroxene and that of bulk Cachari contains only pyroxene. Very small amounts of Fe3+ are also present in the bulk samples, but are attributed to surface contamination. The RT spectra of the D’Orbigny and Cachari glasses are fitted with three doublets, which are assigned to Fe2+ at three different octahedral positions. No Fe3+ was detected in the glass samples. The spectra of the glasses measured at 4.2 K show the presence of relaxation effects. The results suggest a certain degree of structural ordering in these glasses.