Northwest Africa 12919 (NWA 12919)

Morocco

Purchased: June 2019

Classification: Martian meteorite (Shergottite)

History: Purchased in July 2019 from Abdellah Afiniss via the internet.

Physical characteristics: The main mass is a 7.5 g irregular, ellipsoidal, green-gray stone with no fusion crust.

Petrography: (C. Herd and A. Sheen, UAb) Medium-grained basaltic assemblage of pyroxene (~60 vol.%) and maskelynite (~30 vol.%), plus minor titanomagnetite, ilmenite, merrillite, chlorapatite, and Fe-sulfides, and trace olivine, glassy mesostasis, and baddeleyite. Pyroxene grains range between 200 µm to 800 µm in length and consist of augite cores with pigeonite rims. Maskelynite grains are up to 1.2 mm in length.

Geochemistry: (C. Herd and A. Sheen, UAb) Pyroxene displays two distinct compositional trends: pigeonite (Fs₄₅En₄₁Wo_13-Fs₇₂En₁₅Wo₁₃, average Fs₆₃En₂₃Wo₁₄, FeO/MnO=37; n=85) and augite (Fs₂₆En₃₃Wo_40-Fs₅₄En₁₇Wo₂₉, average Fs₃₈En₂₉Wo₃₃, FeO/MnO=32; n=83). Pigeonite adjacent to late-stage melt pockets has Fe-rich compositions reaching Fs₇₆En₁₀Wo_14. Maskelynite is Ab_43-57An_40-56Or_1-4 (n=21). Olivine grains (n=3) are highly fayalitic (Fa_88-93; FeO/MnO=58-65) and associated with mesostasis.

Classification: Martian (shergottite)

Specimens: Entire specimen of 7.5 g, including one thin section, at UAb.