MOSSBAUER-SPECTROSCOPY, X-RAY-DIFFRACTION, AND ELECTRON-MICROPROBE ANALYSIS OF THE NEW HALFA METEORITE

Mossbauer spectroscopy, x-ray diffraction (XRD) measurements, and elec tron microprobe analysis (EMPA) have been carried out for the investig ation of a newly fallen Sudanese meteorite named New Halfa. The room t emperature Mossbauer spectrum is fitted with three sextets and two dou blets. The sextets are assigned to Fe in troilite, kamacite, and taeni te, and the two doublets are assigned to Fe2+ in olivine and pyroxene (no Fe3+ was found). The microprobe trace of Ni concentration across a kamacite-taenite-kamacite area shows a high-Ni concentration at the i nterfaces between kamacite and taenite. From the microprobe analysis, olivine appears to have a constant composition, whereas pyroxene has a varying composition. The mole fractions of the Fe end members of oliv ine (fayalite) and pyroxene (ferrosilite) are found to be 23.5% and 23 .2%, respectively. Accordingly, the New Halfa meteorite is classified as an ordinary L-type chondrite.