from The Meteoritical Bulletin, No. 105
Northwest Africa 10783 (NWA 10783)
Lunar Meteorite (anorthosite)
History: Found in the Almahbas region near the frontier between Morocco and Algeria.
Physical characteristics: The stone is a breccia with no visible fusion crust. The type specimen is mostly light colored with metal specks, and there is a dark zone at one end.
Petrography: (R. Hewins, S. Pont, B. Zanda, MNHNP) Most of the prepared section is a poikilitic anorthosite resembling Apollo 77017. It consists of plagioclase phenocrysts up to 2 mm in length set in pyroxene poikilitic to stubby tiny plagioclase laths (down to 20 μm) and to olivine granules (~50 μm). Both pigeonite and augite are present, but with no obvious exsolution. Minor minerals include chromite, ilmenite, baddeleyite, taenite and kamacite. There is a dark sliver of breccia matrix at the end of the section containing a huge variety of clast types, 1 mm or smaller. These include crystal clasts (olivine, pigeonite, augite, anorthite, chromite and a silica polymorph), breccia clasts, and lithic clasts often with elongated plagioclase laths.
Geochemistry: Mineral compositions and Geochemistry: (R. Hewins and S. Pont, MNHNP) The olivine composition is Fa34.1±1.5, with FeO/MnO 119±14. Pyroxenes are pigeonite Fs25.4Wo11.1 and augite En49.6Fs19.2Wo31.2. Plagioclase is An94.0±0.6Ab5.5±0.6Or0.5±0.2. Taenite contains ~37% Ni. Mineral compositions are similar to those of Apollo 77017, but olivine is a little less ferroan.
Classification: (R. Hewins MNHN, L. Labenne Paris) Lunar poikilitic anorthositic breccia.
Specimens: The type specimen consists of 3.78 g and 0.63 g at MNHNP. The remaining 17.6 g minus sawdust has been sold in the form of thin slices by Labenne.
My sample of Northwest Africa 10783 is from the light colored clast (lower photo above), which I would call a KREEP-bearing, metal-rich, feldspathic impact-melt breccia on the basis of the texture and composition (6.0% FeO, 3.4 ppm Sm, 16 ppb Ir). NWA 10783 appears to be another meteorite that, like SaU 169 and NWA 7022, is a regolith breccia dominated by a large clast of impact-melt breccia. Compositionally, NWA 10783 is most similar to the NWA 8641 clan and may, in fact, simply be a large clast in from the NWA 8641 meteorite.
Meteoritical Bulletin Database
Korotev R. L. and Irving A. J. (2021) Lunar meteorites from northern Africa. Meteoritics & Planetary Science, 206–240.