Lunar Meteorite: Northwest Africa 4932

northern Africa

Northwest Africa 4932 (top, 93 g) and sawn face (bottom). Photo credit: by Greg Hupé

Two sides of a slice of NWA 4932 (photo credit: by Greg Hupé)

Up close in the lab. NWA 4932 contains many small grains of iron-nickel metal. Photo credit: Randy Korotev

from The Meteoritical Bulletin, No. 94

Northwest Africa 4932 (NWA 4932)

Algeria
Find: 2007 October
Mass: 93.3 g (1 piece)

Achondrite (lunar, feldspathic breccia)

History: Purchased by Greg Hupé from a Moroccan dealer in Tagounite, Morocco in October 2007.

Physical characteristics: A single, light colored 93.3 g stone. The interior is light gray, mostly very fine grained with a few white clasts (Fig. 2), and prominent but sparsely distributed metal grains (surrounded by hydroxide staining).

Petrography (A. Irving and S. Kuehner, UWS): Breccia composed of small gabbroic to troctolitic clasts (granular aggregates of rounded olivine grains and calcic plagioclase enclosed within low-Ca pyroxene with accessory Ti-chromite and troilite), sparse large grains of kamacite (up to 1 mm, partly altered to iron hydroxide) and rare large grains of silica polymorph in a dominant, very fine grained matrix of the same phases. There are secondary (terrestrial) veinlets and small patches of calcite.

Geochemistry: Low-Ca pyroxene (Fs22.3-22.8Wo5.9-5.3, FeO/MnO = 51.9-53.0; Fs20.8-36.1Wo7.4-12.0, FeO/MnO = 56.5-58.3), olivine (Fa27.2-36.9, FeO/MnO = 87.7-96.3), plagioclase (An94.9-96.4Or0.3-0.1).

Bulk composition: (R. Korotev, WUSL): FeO 8.5 wt.%, Sc 19.2 ppm, Sm 1.1 ppm, Th 0.6 ppm, Ni 450 ppm.

Classification: Achondrite (lunar, feldspathic breccia).

Specimens: A total of 18.7 g and one polished thin section are on deposit at UWS. The main mass is held by Mr. G. Hupé.

Randy Says…

NWA 4932 is a crystalline impact-melt breccia that is moderately mafic but low KREEP elements. It’s compositionally and texturally very similar to SaU 300, collected ~3400 km away. The two stones may have been blasted off the Moon by a common impact.

More Information

Meteoritical Bulletin Database

NWA 4932

References

Calzada-Diaz A., Joy K. H., Crawford I. A., and Nordheim T. A. (2015) Constraining the source regions of lunar meteorites using orbital geochemical data. Meteoritics & Planetary Science 50, 214-228.

Calzada-Diaz A., Joy K. H., and Crawford I. A. (2016) Investigation of lunar meteorites potentially sourced from cryptomare regions. 47th Lunar and Planetary Science Conference, abstract no. 2075.

Hidaka H., Nishiizumi K., Caffee M., and Yoneda S. (2019) Samarium isotopic compositions of lunar meteorites. 82nd Annual Meeting of the Meteoritical Society, abstract no. 6279.

Korotev R. L., Irving A. J., and Bunch T. E. (2008) Keeping up with the lunar meteorites – 2008. Lunar and Planetary Science XXXIX, abstract no. 1209.

Korotev R. L, Zeigler R. A., Jolliff B. L., Irving A. J., and Bunch T. E. (2009) Compositional and lithological diversity among brecciated lunar meteorites of intermediate iron composition. Meteoritics & Planetary Science 44, 1287-1322.

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