Northwest Africa 17031 (NWA 17031) Purchased: 2024 Classification: Ureilite History: Reportedly found in Algeria in January 2024 and bought later in Mauritania by Mohamed Ali Loud from Al Bouhali Mahmoud-Hamadat Petrography: (K. Metzler, IfP) Coarse-grained ultramafic rock, consisting of olivine and pyroxene grains with sizes up to several mm. Reduction features in olivine, i. e., reverse zoning and occurrence of tiny Ni-free metals at the margins, along cracks, and within the grains. Graphite occurs along silicate grain boundaries. Geochemistry: Mineral compositions and geochemistry: Mean mineral chemistry: Olivine cores: Fa20.7±0.2 (Fa20.4-21.1); Fe/Mn (at.): 50.3; CaO: 0.4 wt% (n=12). Low-Ca pyroxene: Fs17.1±0.2 Wo9.1±0.2 (Fs16.9-17.6 Wo8.7-9.4); n=13. The mean concentration of Cr2O3 (wt%) in olivine and pyroxene is 0.6 and 1.3, respectively. Classification: Ureilite, based on modal composition, mineral chemistry, occurrence of considerable amounts of graphite, and typical reduction features in olivine. Shock stage: U-S2 Weathering grade: moderate Classifier: K. Metzler, IfP. This lot has no reserve price and comes with its certificate of authenticity. Thanks for your interest.