Lunar Meteorite: Northwest Africa 12279

from The Meteoritical Bulletin, No. 107

Northwest Africa 12279 (NWA 12279)

Tindouf, Algeria
Purchased: 2016 October 10
Mass: 1830 g (1 piece)

Lunar Meteorite (feldspathic breccia)

History: The meteorite was purchased in Denver USA by Zhouping Guo and Guobing Zhong on September, 2017 from Adam Aaronson.

Physical characteristics: A single bulk specimen, with sepia fresh fusion crust and low weathering degree. A large impact molten mass was observed in the specimen.

Petrography: This lunar meteorite comprises two petrographic areas: impact melt breccia and anorthosite. The anorthosite includes forsterite, pigeonite, low-Ca pyroxene, plagioclase and minor minerals such as ilmenite, chromite, quartz and other opaque minerals. It has a subophitic structure. The impact-melt breccia contains various types of lithic clasts (anorthosite, olivine-gabbro, gabbro), mineral and glassy fragments. The matrix consists of very fine-grained, cryptocrystalline (~0.1mm) and vitric particles with sporadic small vesicles.

Geochemistry: (J.K. Zhou, H.Y. Chen, Z.P. Xia, Guilin University of Technology, China): Olivine, Fa_12.8-46.3Fo_53.8-87.3, FeO/MnO=66.3-96.9 (n=29); Orthopyroxene, Fs_15.5-32.2Wo_2.98-4.22En_64.9-80.3, Fe/Mn(mol)=_54.5-69.3 (n=3); Pigeonite: Fs_23.2-53.1Wo_7.19-23.7En_39.8-57.4, Fe/Mn(mol)=51.1-61.7 (n=6); Augite, Fs_8.42-44.4Wo_31.4-44.1En_18.7-47.5, Fe/Mn(mol)=37.1-53.9 (n=14); Plagioclase: An_92.9-98.5Or_0.06-0.69 (n=15); Spinel: MgO, 20.1%-23.6%; Al₂O₃, 59.5%-69.2%; Cr₂O₃, 3.91%-6.00%; FeO,6.05%-7.46%.

Classification: Lunar (anorthositic impact-melt breccia)

Specimens: 30.2 g including one polished thin section are deposited in College of Earth Sciences, Guilin University of Technology, China; Remaining material with Guobing Zhong and Zhouping Guo.

Randy Says…

I have not studied Northwest Africa 12279. In a thorough study of the meteorite, Chen et al. (2023) describe it not as a fragmental breccia but a largely unbrecciated “Mg-spinel-bearing troctolitic anorthosite” with 82% plagioclase, 12% olivine (Fo_88.5 cores), 0.8-1.5% spinel, and ~1% silica with veins of impact melt. I am not aware of any other lunar meteorite like it. It is more feldspathic than the otherwise similar Dhofar 303 clan. Chen et al. (2023) appear to not have studied the “large impact molten mass” mentioned in the MetBull description. The meteorite oriented and is roughly spherical with a nearly complete, smooth fusion crust with flow lines.

More Information

Meteoritical Bulletin Database

NWA 12279