The interior and the fusion crust in Sariçiçek howardite: Study using X-ray diffraction, magnetization measurements and Mössbauer spectroscopy.

Abstract

The meteorite Sariçiçek, a 2015 howardite fall in Turkey, was analyzed using various physical techniques. Both the interior and the fusion crust were studied by optical and scanning electron microscopy with energy dispersive spectroscopy, X-ray diffraction, magnetization measurements and Mössbauer spectroscopy. The main and minor iron-bearing phases such as orthopyroxene, Ca-poor and Ca-rich clinopyroxene, chromite with hercynite, Fe2+ and Fe3+ ilmenite, troilite, α-Fe(Ni, Co), α2-Fe(Ni, Co) and γ-Fe(Ni, Co) phases were identified. The ratios of Fe2+ occupancies in the M1 and M2 sites in the silicate phases as well as the equilibrium Fe2+ and Mg2+ cations distribution temperatures (Teq) for orthopyroxene were estimated using X-ray diffraction and Mössbauer spectroscopy, which appeared to be in a good agreement: for example, Teq were 886 and 878K, respectively. The glass-like fusion crust of Sariçiçek consists of orthopyroxene with ferrous and ferric compounds that are likely products of combustion and melting.