The Meteoritical Bulletin, No.
Northwest Africa 10783
2015; Purchased: 2015 May 01
in the Almahbas region near the frontier between
Morocco and Algeria.
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.
(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.
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.
(R. Hewins MNHN,
L. Labenne Paris) Lunar
poikilitic anorthositic breccia.
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.