Angrite 1

Oued Namous 001 pairing

Oued Namous 001 (ON 001)  32°00’40.73"N, 00°21’46.17"W

Place of discovery: Bechar, Algeria

Date of discovery: 2021

Classification: Angrite

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 Fs22.1±3.0Wo51.1±1.3, Fe/Mn=84±6, Al2O3 (wt%)=6.7±1.6, TiO=1.3±0.3 (wt%), n=6; Al-Ti bearing hedenbergite Fs45.4±3.4Wo51.6±1.3, Fe/Mn=136±14, Al2O3=6.0±1.8 (wt%), TiO=3.0±1.0 (wt%), n=5; olivine Fa58.8±19.0Lrn5.6±2.1, range Fa32.3-87.6, Fe/Mn=86±12, n=15; kirschsteinite Fa61.1±2.4Lrn34.4±1.6, Fe/Mn=73±2, n=4; plagioclase An99.7±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.

Specimens: 22.5 g on deposit at UNM, Mark Lyon holds seven pieces at 865 g plus 230 g of smaller fragments, Luc Labenne holds a single stone of 307 g.

Mass (g): 1402

Pieces: 7

Shock stage: low

Weathering grade: low

Classifier: C. Agee, UNM

Main mass: Mark Lyon


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