Fe2+ partitioning between the M1 and M2 sites in silicate crystals in some stony and stony-iron meteorites studied using X-ray diffraction and Mössbauer spectroscopy

Abstract

Study of the Fe2+ partitioning among the crystallographically non-equivalent M1 and M2 sites in silicate crystals such as olivine, orthopyroxene and clinopyroxene is of interest to analyze their features and thermal history. Especially, this is important for investigation of extraterrestrial silicate crystals in meteorites. We discuss the results of the study of Fe2+ partitioning among the M1 and M2 sites in silicate crystals in some stony and stony-iron meteorites based on the data obtained by means of two independent techniques: X-ray diffraction and Mössbauer spectroscopy with a high velocity resolution. It is possible to evaluate the ratios of the Fe2+ occupancies of the non-equivalent M1 and M2 sites in olivine, orthopyroxene and clinopyroxene crystals. Estimation of the Fe2+ and Mg2+ cations distribution coefficient and the temperature of equilibrium cation distribution for olivine and orthopyroxene in some stony and stony-iron meteorites is also considered. A good agreement between results obtained by means of two independent techniques is shown.