Lunar Meteorite: Northwest Africa 16784
from The Meteoritical Bulletin, No. 113 Northwest Africa 16784 (NWA 16784)(Northwestern Africa) Lunar meteorite (troctolite melt breccia) History: Acquired in January 2024 by Shun-Chung Yang from Ali Mftah in Algeria. Physical Characteristics: Many pieces with weathered exteriors and no discernable fusion crust. Petrography: (D. Sheikh, Cascadia) Sample is a polymict breccia comprised of mm to cm-sized lithic (e.g., anorthosites, troctolites, pink spinel troctolites, impact-melt clasts) and mineral (e.g., isolated grains of olivine) clasts set within a dark melt matrix containing some observable vesicles. A variation in the matrix texture was observed across the sample, with at least two noticeable textures: 1) a texture comprised of olivine (~20 μm, ~15 vol. %) and pyroxene (~10 μm, <5 vol. %) poikilitically enclosed within a plagioclase-rich (~80 vol. %) melt; 2) a texture comprised of olivine grains (~20 μm, <5 vol. %) surrounded by radiating laths of plagioclase (~66 vol. %), olivine (~20 vol. %), and minor pyroxene (~9 vol. %) (laths vary from ~1-50 microns in longest dimension). Accessory phases identified throughout the sample include spinel, chromian spinel, Ca-phosphates, troilite, and ilmenite. Geochemistry: Olivine (Fa25.0±3.5, range Fa15.7-30.6, Fe/Mn = 81±7, n=27), Pigeonite (Fs19.2±4.6Wo14.9±6.2, range Fs10.4-27.2Wo5.4-22.0, Fe/Mn = 56±10, n=10), High-Ca Pyroxene (Fs14.6±5.3Wo34.1±6.7, range Fs6.3-22.1Wo25.1-41.1, Fe/Mn = 58±5, n=6), Calcic Plagioclase (An95.7±0.6, range An94.3-97.2, n=28). Classification: Lunar (anorthositic troctolite melt breccia) based on the overall predominance of plagioclase, and lesser olivine, within the various melt matrix lithologies according to Stoeffler et al. (1980). Possibly paired with either Touat 008 or NWA 16294 based on similarly described textural and/or chemical features. Specimens: 21 g at Cascadia, main mass with Shun-Chung Yang. |
Randy Says… I have not studied Northwest Africa 16784. The reported find location of Touat 004 is 770 km to the east, so the stones are unlikely terrestrial pairs. The find location of NWA 16294 is not reported. |
More InformationMeteoritical Bulletin Database NWA 16xxx |