Radioactive Isotopes as a Tool for Pairing Identification of the HAH 346—Hammadah al Hamra 346—Ordinary Chondrites from Two Separate Find Areas

Abstract

In this study, low-background gamma spectrometry was used to confirm the identity of a set of ordinary chondrites found in 2018 and 2019, by different expeditions, in a part of the Al-Hamada al-Hamra desert, in the region of Al-Dżabal al-Gharbi, in Libya. Ten specimens of ordinary chondrites from two different campaigns were investigated. An analysis was carried out using a unique gamma spectrometry system to obtain the optimal measurement conditions for the quantitative identification of the radioactive isotopes. Chondrite radiometric studies enabled a detailed analysis of the activities of radioactive isotopes—the short-lived 22Na, 54Mn, 60Co, and long-lived 26Al, 40K. For most isotopes, the activities are expected to be similar for ordinary chondrites with the same irradiation history. Short-lived radionuclide concentrations can be considered, as a specific fingerprint of the chondrite terrestrial age, to confirm whether meteorites originate from a single fall. The HaH 346 group of chondrites was classified in February 2021. The data sets have been analyzed based on multivariate chemometric techniques, including K-means, PCA, and clustering analysis, to derive essential information and confirm similarities or significant differences between the studied specimens.