Northwest Africa 13696 (NWA 13696)

(Northwest Africa)

Purchased: 2020

Classification: Primitive achondrite (Winonaite)

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

Physical characteristics: Two brownish fragments partly covered with fusion crust exposing abundant metal grains at the surface.

Petrography: The meteorite shows a recrystallized metamorphic texture with abundant 120 degree triple junctions. It is predominantly composed of 50 to 300 µm sized low-Ca pyroxene, Mg-rich olivine, diopside, and sodic feldspar grains. Low-Ca pyroxene is the most abundant mineral phase and often poikilitically encloses rounded to subrounded feldspar grains. No chondrules were observed. Kamacite, taenite, and troilite are finely dispersed throughout the meteorite. Contains minor chromite and chlorapatite. Some grain boundaries are decorated with secondary Fe-oxides.

Geochemistry: olivine: Fa_4.1±0.1 (Fa_4.0-4.3, FeO/MnO=17±1, n=5); low-Ca pyroxene: Fs_4.8±0.1Wo_1.9±0.1 (Fs_4.7-4.9Wo_1.8-2.0, FeO/MnO=11±1, n=5); diopside: Fs_1.8±0.1Wo_45.5±0.3 (Fs_1.7-2.0Wo_45.1-45.9, FeO/MnO=9±2, n=5); feldspar: An_21.9±0.3Ab_75.3±0.5Or_2.9±0.2, n=5

Classification: Winonaite; likely paired with NWA 13624