Northwest Africa 16400 (NWA 16400)

(Northwest Africa)

Purchased: 2023

Classification: Lunar meteorite

History: Purchased in 2023 by Habib-naji Naji from a meteorite dealer in Algeria.

Physical characteristics: Single stone with minor fusion crust.

Petrography: (D. Sheikh, Cascadia) Sample represents a fragmental breccia comprised of mm-sized angular to sub-rounded lithic and mineral clasts set within a mostly fine-grained matrix. Clast lithologies identified in this sample include anorthosites, norites, olivine gabbronorites, anorthositic gabbronorites, troctolites, pink spinel anorthosites (PSA), impact melt clasts, and other spinel-bearing lithologies; clast lithologies are predominantly Mg-suite in composition, with minor input from lunar ferroan anorthosites (FAN) and magnesian anorthosites (MAN). Minor/accessory phases identified include ilmenite, cordierite, troilite, Fe-Ni metal, chromite, and merrillite.

Geochemistry: Host [Olivine (Fa_19.7±8.4, range Fa_7.7-27.2, Fe/Mn=85±7, n=17); Low-Ca Pyroxene (Fs_11.5±0.7Wo_2.0±1.8, range Fs_10.2-12.8Wo_0.5-4.8, Fe/Mn=47±8, n=30), Pigeonite (Fs_18.8±1.2Wo_14.3±3.6, range Fs_16.8-21.4Wo_8.7-21.5, Fe/Mn=50±5, n=9), High-Ca Pyroxene (Fs_9.4±3.9Wo_38.8±5.5, range Fs_5.0-15.2Wo_26.6-44.4, Fe/Mn=41±10, n=18), Calcic Plagioclase (An_95.2±2.3, range An_89.6-98.2, n=68)]; Pink Spinel Anorthosite (PSA) Clasts [Pink Spinel (Mg#=84.0±0.2, Cr#=3.9±0.1, n=18), Calcic Plagioclase (An_95.6±0.4, range An_94.8-96.2, n=21)].

Classification: Lunar. Likely paired with NWA 15500 based on texture and clast lithologies.

Specimens: 11.3 g type specimen at Cascadia, main mass, D. Shiekh.