Northwest Africa 10597 (NWA 10597)

Morocco

Purchased: 2016 Feb

Classification: Lunar meteorite (basalt)

History: Purchased by Ke Zuokai in Feb. 2016 at Tucson mineral show from an anonymous Moroccan dealer.

Physical characteristics: A single stone with a complete fresh fusion crust.

Petrography: The meteorite is a medium-grained unbrecciated basalt composed of elongate, zoned pyroxene (up to 1 mm) grains and plagioclase (up to 1.2 mm) laths. Olivine phenocrysts are up to 350 µm, and commonly have inclusions of hercynite, Ti-Al-rich chromite, pigeonite or rarely augite with intergrowth of Na-rich glass. Most pyroxene grains are pigeonite with a minor amount of augite. A few pigeonite grains have augite rims. Plagioclase  is partly converted to maskelynite. Late-stage mesostasis is composed of silica, Fe-rich olivine, Fe-rich pyroxene, K-rich glass, ilmenite, pyrrhotite, baddeleyite, and elongate, skeletal apatite and merrillite. Other opaque phases include chromite, Ti-rich chromite, troilite, ulvöspinel, tranquillityite, zirconolite and a few FeNi metal. Shock veins and impact melt pockets are present. Mineral modes (vol%): olivine = 6, pyroxene =52, plagioclase = 32, silica=3, ilmenite = 4, mesostasis + impact melt = 3.

Geochemistry: Plagioclase, An_85.1±2.3Or_0.4±0.3 (An_78.5-87.8Or_0.2-0.8, n=20); olivine zoned from Fo_58.2-49.9 (cores) to Fo_36.6-40.7 (rims) (Fa_46.5-93.1, n=13; FeO/MnO = 81.9-106.8, average: 91±7); zoned pigeonite, core En_57.7-51.6Wo_8.9-16.8, rim En_7.2-22Wo_20.2-31.5 (Fs_28.5-79.6Wo_10.1-25.5, n=23), and augite, Fs_21.3-52.5Wo_28.4-39.3 (Wo_32.9-36.2 En_11.9-38.8, n=9), with pyroxene FeO/MnO = 30.8-81.9, average: 60±10; mesostasis olivine and pyroxene, Fo_2.3-13.5 and En_1-3Wo_14-17. Chemical compositions (wt.%) of fusion crust: MgO 7.0, FeO 23.5, Al₂O₃ 7.9, SiO₂ 47.4, CaO 10.6, TiO₂ 3.5.