Lunar Meteorite: Northwest Africa 12839

from The Meteoritical Bulletin, No. 108

Northwest Africa 12839 (NWA 12839)

(northwestern Africa)
Purchase: 2019 June
Mass: 68.75 g (1 piece)

Lunar (diabase)

History: Purchased by Ben Hoefnagels in June 2019 from a dealer in Agadir, Morocco.

Petrography: (A. Irving, UWS and P. Carpenter, WUSL) Diabasic texture (mean grainsize 0.5 mm). Composed primarily of zoned clinopyroxene and maskelynite with accessory blade-like ilmenite, very sparse zoned olivine (~3 vol.%), Cr-Ti oxides, baddeleyite, probable zirconolite, troilite, merrillite, silica polymorph, fayalite and hedenbergite. Dark shock glass is present in pockets (vesicular) and as cross-cutting veinlets.

Geochemistry: Subcalcic augite (core Fs_28.8Wo_26.3, FeO/MnO = 50; rim Fs_72.4Wo_23.6, FeO/MnO = 77), augite (core Fs_21.2Wo_38.7, FeO/MnO = 47; rim Fs_81.5Wo17.7, FeO/MnO =81), pigeonite (core Fs_41.8Wo_12.9,FeO/MnO = 65; rim Fs_69.8Wo_22.4, FeO/MnO = 77), olivine cores (Fa_37.6-39.5, FeO/MnO = 92-94, N = 3), olivine rims (Fa_54.1-68.2, FeO/MnO = 93-110, N = 3), fayalite (Fa_99.2, FeO/MnO = 95), maskelynite (An_87.5-88.2Or_0.3, N = 2).

Classification: Lunar (mare diabase, clinopyroxene-rich, olivine-poor).

Specimens: 14.1 g including one polished thin section at UWB; remainder with Mr. B. Hoefnagels.

Randy Says…

I have not studied Northwest Africa 12839. I assume that it is unpaired with other basaltic lunar meteorites from the description. A diabase is a fine-grained volcanic rock solidified from a magma that, unlike a basalt, did not erupt onto the surface of a planet but beneath the surface.

More Information

Meteoritical Bulletin Database

NWA 12839

References

Burney D., Neal C. R., Irving A. J., Carpenter P. K., Tepper J. H., and Hoefnagels B. (2020) Petrology and chemical composition of lunar mare diabase Northwest Africa 12839: Comparisons with Apollo basalts. 51st Lunar and Planetary Science Conference, abstract no. 2613.