MORPHOLOGY AND PHYSICO-CHEMICAL CHARACTERISTICS OF AN IRON FRAGMENT FROM CHACO PROVINCE

This study aims to demonstrate that the investigated sample is nickelrich, a signature of the meteorites composed of iron, in order to establish if studied sample belongs or not to Campo del Cielo meteorite group. The discrete structure found in meteorites is a fingerprint fully justified by structural analysis using optical microscopy (OM) and scanning electron microscopy (SEM), X-ray diffraction (XRD), as well as by elemental content using energy dispersive spectrometry (EDS) and inductive coupled plasma mass spectrometry (ICP-MS). The presence of crystalline phase's kamacite and taenite was confirmed, with a good correlation between experimental results and standard diffraction data (i.e. ICDD card numbers of minerals). Vickers hardness tests (HV 0.1 and HV 1.0) were achieved in accordance with STAS 492/1-85 and the average values (247-255.2 N/mm(2)) include the fragment into iron meteorite hardness category. The isotopic signature of kamacite (delta Fe-56/54 = 0.15 parts per thousand and delta(62/60) Ni = 0.81 parts per thousand) determined by ICP-MS, certify the origin of metallic fragment in Campo del Cielo meteoritic group.