Northwest Africa 14185 (NWA 14185)

(Northwest Africa)

Purchased: 2021 Jul

Classification: Enstatite achondrite (Aubrite)

History: The meteorite was purchased from a dealer in Algeria.

Physical characteristics: White-grayish fragments with minor fusion crust and fine black shock melt veins exposed at the suface. Several orange-brownish stained areas sometimes with silvery metal grains are visible.

Petrography: The meteorite is a breccia predominantly composed of up to 1.5 cm sized enstatite grains with fine diopside exsolutions and several up to 5 mm sized twinned diopside grains that contain abundant enstatite exsolution lamellae. Rims of larger diopsides are often devoid of exsolutions. Opaque phases include Ti-bearing troilite, daubréelite, alabandite, brezinaite, schreibersite, and Si-bearing kamacite. The meteorite is highly shocked, i.e., enstatite shows several sets of planar fractures, diopside and enstatite shock strong undulatory extinction, and it contains abundant thin black shock melt veins and pockets. Neither forsterite nor plagioclase have been found in the two sections studied. No relict chondrules were observed.

Geochemistry: enstatite: Fs_0.04±0.06Wo_0.8±0.1 (Fs_0.00-0.20Wo_0.7-0.9, n=27); diopside exsolution lamellae: Fs_0.00Wo_44.5-45.9, n=3); diopside: Fs_0.01±0.03Wo_45.4±0.2 (Fs_0.00-0.10Wo_44.9-45.9, n=12); enstatite exsolution lamellae: Fs_0.03±0.05Wo_1.5±0.7 (Fs_0.00-0.10Wo_0.6-2.4, n=10); diopside exsolution-free rim: Fs_0.02±0.04Wo_48.1±0.1 (Fs_0.00-0.10Wo_47.9-48.3, n=5); troilite (Ti = 2.7 wt.%); kamacite (Si = 1.1 wt.%)