Mineralogy and 57Fe Mössbauer spectroscopy of opaque phases in the Neuschwanstein EL6 chondrite

Abstract

This study presents compositional data and 57Fe Mössbauer spectra, taken at 295 K and 85 K, of two fragments of the enstatite (EL6) chondrite Neuschwanstein that fell near the famous Neuschwanstein castle (Bavaria, southern Germany) on April 6, 2002. Main silicate minerals are enstatite (Fs 2) and plagioclase (An 20), the main opaque minerals are kamacite and troilite. Small amounts of oldhamite, daubreelite, and schreibersite have been found. The presented Mössbauer data are the first data gathered for an EL6 chondrite. The dominant parts of each Mössbauer spectrum consist of two six-line patterns due to the presence of ferromagnetic phases kamacite and troilite. In contrast to other chondrites, peaks of other iron species in the central parts of the spectra are missing due to an extremely low content of Fe-bearing paramagnetic components. The hyperfine interaction parameters for kamacite are internal magnetic hyperfine field Hhf = 333.2 kOe, isomer shift (relative to a metallic Fe foil) IS = 0.01 mm/s, quadrupole splitting QS = 0 mm/s, line width W = 0.41 mm/s. The data for troilite are Hhf = 305.5 kOe, IS = 0.75 mm/s, QS = 0.85 mm/s, W = 0.34 mm/s.