Northwest Africa 14900 (NWA 14900)

(Northwest Africa)

Purchased: 13 March 2022

Classification: Lunar meteorite (frag. breccia)

History: Purchased on March 13, 2022, by Matthew Stream from Aliyen Faida’llah in Morocco.

Physical characteristics: Eight stones with slightly weathered fusion crust.

Petrography: (D. Sheikh, Cascadia) Sample represents a lunar polymict breccia composed of angular to sub-rounded mm-sized lithic and mineral clasts set within a glassy to fine-grained matrix containing regions of isolated melt pockets, shock melt veins, schlieren, and vesicles. Lithic clast lithologies include: anorthositic clasts, noritic clasts, troctolitic clasts, impact melt-rich clasts, basaltic clasts, and a ~2 mm dunite clast; mineral clasts include isolated grains of olivine (some displaying strong normal zoning), pyroxene (some displaying exsolution lamellae), and plagioclase (mix of fractured and smooth grains). Accessory phases include ilmenite, silica glass, Cr-rich spinel, troilite, and Fe-Ni metal.

Geochemistry: Olivine (Fa_23.4±12.8, range Fa_9.0-44.6, Fe/Mn=85±8, n=21), Low-Ca Pyroxene (Fs_32.6±13.2Wo_4.0±0.9, range Fs_17.9-46.7Wo_2.8-5.1, Fe/Mn=51±6, n=5), Pigeonite (Fs_30.1±6.7Wo_11.1±3.3, range Fs_19.5-40.8Wo_6.9-20.2, Fe/Mn=50±6, n=19), High-Ca Pyroxene (Fs_19.3±4.9Wo_38.0±3.7, range Fs_8.6-25.0Wo_33.3-43.2, Fe/Mn=45±4, n=9), Calcic Plagioclase (An_95.5±1.6, range An_90.2-97.1, n=22); Dunite clast [Olivine (Fa_9.1±0.1, range Fa_9.0-9.1, Mg#=91, Fe/Mn=80±10, n=8), Cr-rich spinel (Cr#=80.6±2.2, Mg#=53.8±4.5, n=3)].

Classification: Lunar (fragmental breccia) due to polymict nature of the sample.

Specimens: 20.2 g at Cascadia, main mass with Matthew Stream.