Northwest Africa 15717 (NWA 15717)

(Northwest Africa)

Purchased: 2022

Classification: Ungrouped achondrite

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

Physical characteristics: Several light grayish to cream-coloured fragments with patches of black fusion crust.

Petrography: The meteorite is an achondritic breccia composed up to 2 cm sized lithic and up to 8 mm sized euhedral to subhedral mineral fragments in a fine-grained cataclastic and related matrix. Most abundant in all lithologies are Mg-rich, mostly compositionally homogeneous olivine (about 75 vol%) and low-Ca pyroxene (about 20 vol%). Zoned olivine and exsolved pyroxenes are rare. Accessories (about 5 vol%) include silica, chromite, FeS, kamacite, and taenite. Contains augite-chromite and orthopyroxene-chromite symplectites. No feldspar found.

Geochemistry: compositions of individual olivine grains: Fa_9.8±0.1, FeO/MnO=37±3, n=7; Fa_16.7±0.1, FeO/MnO=37±1, n=7; Fa_18.6±0.1, FeO/MnO=38±2, n=10; Fa_20.1±0.1, FeO/MnO=41±2, n=7; Fa_24.9±0.1, FeO/MnO=40±1, n=7; fayalite: Fa_82.7±0.2, FeO/MnO=39±1, n=5; zoned olivine: Fa_25.3±3.1 (Fa_21.6-29.1, FeO/MnO=43±3, n=7); low-Ca pyroxene: Fs_34.5±0.3Wo_3.6±0.2, FeO/MnO=28-31, n=7); low-Ca pyroxene host to exsolution lamellae: Fs_65.4±0.4Wo_7.4±0.1 (Fs_64.7-65.7Wo_7.2-7.6, FeO/MnO=24-27, n=7); Ca-pyroxene exsolution lamellae: Fs_38.5±1.8Wo_38.1±2.2 (Fs_37.3-41.6Wo_34.3-40.0, FeO/MnO=29-34, n=7); chromite: Mg#41.5±0.8, Cr#70.2±0.2, n=7

Classification: Ungrouped achondrite, lherzolitic breccia. Likely paired with NWA 12217, NWA 12319, NWA 12562, NWA 13954, NWA 14993, and NWA 15663.