FORENSIC CLASSIFICATION OF METEORITES: THE CASE OF AN ORIENTED SPECIMEN FROM THE BELGIAN ANTARCTIC METEORITE COLLECTION

Introduction: The meteorite classification processes require a sequence of semi-destructive to destructive analyses to elucidate the internal texture and chemical composition of the sample. Several methods have been proposed for classifying meteorites using a non-destructive approach such as magnetic susceptibility [1] or 3D petrographic analysis [2]. Specimens with unique orientation forms such as cone or shield-shaped, are often prioritized for non-destructive classification due to their significant exhibition value and insight into the aerodynamics of extraterrestrial material during their atmospheric entrance [3,4]. In this study, we present a description employing non-destructive analysis to classify a newly found flattened shield-shaped Antarctic meteorite discovered during the Belgian meteorite reconnaissance expedition 2022-2023 in the Sør Rondane area, East Antarctica [5]. This approach promises to provide detailed internal structural and information on physical properties without compromising the integrity of the sample. Methods: We utilized the X-ray Computed Tomography (XCT) RX Solutions EasyTom150 device at the Institute of Natural Sciences (Brussels, Belgique) to analyze the sample with dimensions of 37.1 mm x 44.0 mm x 52.6 mm (Fig. 1). A copper filter of 0.4 mm was used. The sample was scanned at a voxel size of 58.2 μm using the large focal spot mode at 145 kV, 38 W and 260 μA. We employed the program 3D Slicer [6] to analyze the three-dimensional properties and calculate the physical parameters. Additionally, magnetic susceptibility measurements were conducted on the field using an SM30 instrument. Preliminary results: Various forms of deformation, notably radial extension features, were detected, likely indicative of shock experiences undergone by the sample before entering the Earth’s atmosphere, hence corroborating its extraterrestrial origin (Fig. 1). Preliminary magnetic susceptibility measurement on the field indicated a value typical of L chondrites (log χ ~ 4.7 [5]). The interior XCT slices reveal that the sample comprises a dense metallic phase with few non-metallic inclusions, primarily located on the face opposite to the entry direction (red arrow in Fig. 1b). The total volume measures 22.09 cm3, with a corresponding mass of 151.1 g, indicating a meteorite bulk density of 6.8 g cm-3 comparable to iron meteorites (bulk density between 7 and 8 g cm-3 [7]). This is at odds with the preliminary magnetic susceptibility measurement. Additional non-destructive analyzes will be needed, notably μ-XRF measurements to offer a better comprehension of the origin of the sample. This underlines the difficulty of classifying a sample in a non-destructive manner

Proceedings, RBINS Collection(s), International Redaction Board, Abstract of an Oral Presentation or a Poster