Northwest Africa 12543 (NWA 12543)

Northwest Africa

Purchased: 2019

Classification: Primitive achondrite (Winonaite)

History: Reportedly found June 2018, purchased by Zuokai Ke in February 2019 from a Moroccan meteorite dealer.

Physical characteristics: Single stone, dark color, partial fusion crust on exterior. Saw-cut surfaces shows scattered fine-grained metal set in a mosaic of dark colored silicate minerals.

Petrography: (C. Agee, UNM) Microprobe examination of a polished mount shows a texturally equilibrated mosaic of forsterite, enstatite, and diopside with grain size in the range 100-300 μm, many triple junctions are present. Fe-Ni metal makes up approximately 5-10% of this meteorite, most grains are 100-300 μm in diameter, there are also fine veinlets of metal or Fe-oxide throughout. No feldspar was observed.

Geochemistry: (C. Agee UNM) Forsterite Fa_0.6±0.1, Fe/Mn=4±1, n=6; enstatite Fs_1.1±0.2Wo_1.8±0.2, Fe/Mn=2±0, n=3; diopside Fs_1.0±0.6Wo_47.0±0.6, Fe/Mn=2±1, n=3. Oxygen isotopes (K. Ziegler, UNM): 3 acid-washed fragments analyzed by laser fluorination gave δ¹⁸O=4.662, 5.118, 5.583; δ¹⁷O=1.88, 2.12, 2.345; Δ¹⁷O=-0.582, -0.582, -0.603 (linearized, all per mil, TFL slope=0.528).

Classification: Primitive achondrite (winonaite) based on presence of near-end member magnesian silicates and oxygen isotope values that coincide with the winonaite field.

Specimens: 24 g including a probe mount on deposit at UNM, Zuokai Ke holds the main mass.