Northwest Africa 15507 (NWA 15507)

Ouargla, Algeria

Purchased: 2022 Oct

Classification: Angrite

History: Found in eastern Algeria and purchased in October 2022 by Aziz Zad from a dealer in Ouargla, Algeria.

Physical characteristics: A single mass (867 g) partly coated by dark fusion crust and naturally broken into three fitted pieces.

Petrography: (A. Irving, UWS and P. Carpenter, WUSL) Microgabbroic specimen (mean grainsize ~1.4 mm) composed predominantly of zoned Al-Ti-augite, Ca-bearing olivine and anorthite together with accessory kirschsteinite, rhönite, hercynite, low-Ni kamacite, magnetite and troilite.

Geochemistry: Olivine (Fa_56.5-59.9Ln_2.1-4.3, FeO/MnO = 83-85, N = 4), kirschsteinite (Fa_38.6-45.1Ln_47.3-46.7, FeO/MnO = 79-83, N = 2), Al-Ti-augite (Fs_16.7-38.1Wo_53.8-51.9, FeO/MnO = 137-239, Al₂O₃ 5.5-8.5 wt.%, TiO₂ 0.1-1.9 wt.%, N = 6), anorthite (An_99.1-100.0Or_0.0, N = 3), rhönite ([Ca_2.04 (Mg_0.32Fe²⁺_4.25Fe³⁺_0.47Ti_0.33 Al_0.61) (Si_3.74Al_2.26)O₂₀], FeO/MnO = 238-354, N = 3).

Classification: Angrite (microgabbroic, rhönite-bearing).

Specimens: 26.5 g including one polished thin section at UWB; remainder shared equally among WangZ, A. Zad and K. Zad.