Studies and characterizations of the Al Zarnkh meteorite

Abstract

A newly fallen Sudanese meteorite named Al Zarnkh was investigated using room and liquid nitrogen temperature Mssbauer measurements, X-ray diffraction (XRD), and electron probe microanalysis (EPMA) in conjunction with energy dispersive X-ray microscopy. The Mssbauer spectra exhibited strong paramagnetic doublets with magnetic sextets. The doublets are assigned to olivine and pyroxene, while the magnetic sextets are assigned to troilite and kamacite. Based on microprobe analyses and textural studies, olivine is the most abundant phase and occurs as fine to medium grained laths both in the groundmass and in barred olivine chondrules. Both orthopyroxenes and clinopyroxenes are present and these tend to be granular. Plagioclase is an abundant interstitial groundmass phase. Chromites were detected in some groundmass olivine and are highly chromiumand iron-rich with no Fe3+ detected. The kamacite contains small amounts of Co. The mole fraction of the Fe end-member of olivine (fayalite) and orthopyroxene (ferrosilite) are found to be about 28% and 23%, respectively. These values are compared with that obtained from two chondritic meteorites. Based on these results, the studied meteorite is classified as an ordinary LL5 chondrite.