Northwest Africa 15655 (NWA 15655)

(Northwest Africa)

Purchased: 2022

Classification: Lunar meteorite (feldspathic breccia)

History: Three stones weighing 94.0, 103.1, and 249.4 g were purchased in March 2022 by Shun-Chung Yang and Juan Chen from a meteorite dealer in Algeria.

Physical characteristics: Three stones with dark-brown fusion crust.

Petrography: (D. Sheikh, Cascadia) Sample is a breccia comprised of mm to cm-sized sub-angular lithic and mineral clasts set within a fine-grained fragmental matrix containing accessory ilmenite and merrillite. Clast lithologies identified include anorthosites, olivine norites, noritic anorthosites, and anorthositic norites.

Geochemistry: Olivine (Fa_43.9±8.1, range Fa_27.6-59.2, Fe/Mn=89±2, n=9), Low-Ca Pyroxene (Fs_45.0±1.4Wo_3.9±1.4, range Fs_44.0-46.0Wo_2.9-4.9, Fe/Mn=56±3, n=2), Pigeonite (Fs_35.8±6.2Wo_13.6±3.9, range Fs_26.3-48.8Wo_8.2-23.1, Fe/Mn=57±6, n=11), High-Ca Pyroxene (Fs_20.3±1.5Wo_38.9±2.3, range Fs_19.3-21.3Wo_37.2-40.5, Fe/Mn=49±4, n=2), Calcic Plagioclase (An_96.3±1.3, range An_92.4-98.7, n=20).

Classification: Lunar (feldspathic fragmental breccia) comprising a mix of FAN, MAN, and Mg-suite lithologies. An unusual 20 μm grain of near end-member enstatite (Fs_0.4Wo_1.2, Al₂O₃ wt. % ~0.6) was identified within the matrix.

Specimens: 20.09 g at Cascadia, main mass with Shun-Chung Yang and Juan Chen.