Mineralogical characterization of the fusion crust of the Cavezzo L5 Chondrite

On January 1st at 18:26:53 UT, eight stations of the PRISMA network detected a brilliant fireball, named IT20200101, in the skies of northern Italy (Gardiol et al., 2021). Thanks to the involvement of local people by an effective media campaign, two fragments were recovered, weighing 3.12 g (specimen 1) and 52.19 g (specimen 2), three days after the bolide was observed. In this contribution we describe the mineralogical characterization of the fusion crust of sample 2. A thin section of sample 2, and a polished mount with several chips from the fusion crust have been studied by both optical microscopy and by FE-Scanning electron Microscopy. Both Optical observations and micro-chemical analyses of the meteorite interior were consistent with published classification as a L5 ordinary chondrite (Pratesi et al., 2021). The fusion crust displays a complex texture of scheletal and acicular olivine, often with a rim richer in Fe than the core. The small size of most olivine crystal prevented to obtain an accurate composition for most of them. Magnetite dendrites are commonly associated to the olivines. Minor minerals found in the crust include euhedral chromites, ilmenites, plagioclases in aggregates with chromites (Pl-chr assemblages) and a nichel sulphide whose composition is close to Ni2S. One of the two Ni sulphides found display submicroscopic inclusions of metallic Ni.To our knowledge, Ni2S has never been reported before in chondritic material; thus, in order to confirm the composition and in order to determine the structure of this phase, we are planning to cut a slice of one of these grains by FIB and to study this phase by Transmission Electron Microscopy.