OUED NAMOUS 001 (1.806 gram)

Classification:  Achondrite, Volcanic Angrite
Time/Place: 2021 in Bechar, Algeria
Mass: 26kg

History: This meteorite was found approximately 15 km east of a major dry riverbed Wadi Al-Namous (aka Oued Namous) and approximately 10 km north of highway N6B in El Bayadh Province, Algeria, in May 2021. Eight pieces plus many fragments weighing a total of 1402 g were purchased by Mark Lyon in 2022.
Physical characteristics: Dark colored exterior covered in patches of smooth fusion crust. Broken surfaces and saw-cut surfaces reveal a fine-grained mosaic of black, green and white colored crystals with scattered gemmy green olivine phenocrysts up to 8 mm in diameter. Spherical vugs are ubiquitous.
Petrography: (C. Agee and A. Ross, UNM) Reflected light microscopy and electron microprobe analysis showed a subophitic texture of Al-Ti bearing high-calcium pyroxenes (with separate populations of Al-Ti bearing diopside-hedenbergite and Al-Ti bearing hedenbergite), euhedral elongate to stubby anorthite, olivine, kirschsteinite, and minor titanomagnetite and troilite. No metal was detected. Vesicular fusion crust was 100-300 μm thick. Ferromagnesian phases showed core to rim compositional zonation. Olivine showed a positive correlation between calcium content and fayalite content.
Geochemistry: (A. Ross and C. Agee, UNM) Al-Ti bearing salite-ferrosalite Fs_22.1±3.0Wo_51.1±1.3, Fe/Mn=84±6, Al₂O₃ (wt%)=6.7±1.6, TiO=1.3±0.3 (wt%), n=6; Al-Ti bearing hedenbergite Fs_45.4±3.4Wo_51.6±1.3, Fe/Mn=136±14, Al₂O₃=6.0±1.8 (wt%), TiO=3.0±1.0 (wt%), n=5; olivine Fa_58.8±19.0Lrn_5.6±2.1, range Fa_32.3-87.6, Fe/Mn=86±12, n=15; kirschsteinite Fa_61.1±2.4Lrn_34.4±1.6, Fe/Mn=73±2, n=4; plagioclase An_99.7±0.2, n=6; fusion crust (20 μm defocused beam) SiO₂=36.5±0.1, TiO₂=1.1±0.1, Al₂O₃=7.4±0.1, Cr₂O₃=0.06±0.02, MgO=7.5±0.1, FeO=30.0±0.2, MnO=0.33±0.02, CaO=14.1±0.2 (all wt%).
Classification: This is a volcanic angrite based on the significant igneous zoning of olivine and pyroxene. Evidence supporting the angrite classification include the presence of: 1) plagioclase An_>99; 2) Al-Ti bearing high-calcium pyroxenes with Fe/Mn up to 149; 3) kirschsteinite; 4) olivine with Fe/Mn up to 111; and 5) spherical vugs typical of volcanic angrites.