Northwest Africa 6355 (NWA 6355)

Morocco

Found: June 2009

Classification: Lunar meteorite (feldspathic breccia)

History: Found in southern Morocco in June 2009 and purchased by a consortium led by Matt Morgan from a Moroccan dealer in September 2010.

Physical characteristics: A single fine-grained, brittle stone (760 g) with no obvious fusion crust. The interior is dark gray and resembles devitrified glass with dispersed small white clasts.

Petrography: Clast-laden vitric breccia consisting of fine-grained mineral debris (mostly pyroxenes, olivine and anorthite) and sparse polycrystalline igneous clasts in a heterogeneous, "swirly" glassy matrix (in part vesicular). Mineral clasts include anorthitic plagioclase, low-Ca pyroxene, pigeonite, olivine, Mg-bearing ilmenite, kamacitic metal and troilite. Lithic clasts include microgabbronorite (composed of subcalcic augite, orthopyroxene, anorthite, Mg-bearing merrillite, silica polymorph, ilmenite, troilite and baddeleyite).

Geochemistry: Low-Ca pyroxene (Fs_37.5-61.2Wo_2.4-5.2, FeO/MnO = 65-88), pigeonite (Fs_23.5-45.5Wo_10.3-11.1, FeO/MnO = 48-76), subcalcic augite (Fs_13.0Wo_37.0, Fs_17.6Wo_30.1, Fs_25.7Wo_35.0, FeO/MnO = 55-59), augite (Fs_11.3Wo_41.8; FeO/MnO = 49), olivine (Fa_29.5-33.9, FeO/MnO = 81-104), plagioclase (An_91.6-96.1Or_0.5-0.1). Bulk composition (R. Korotev, WUSL): FeO 5.8 wt%, La 13.0 ppm, Sm 6.1 ppm, Yb 3.95 ppm, Th 1.87 ppm.

Classification: Achondrite (lunar, feldspathic breccia). This stone is almost identical in texture, mineral compositions and bulk composition to NWA 4936, NWA 5406 and NWA 6221. It is possibly paired with those stones and is reportedly from the same find location.

Specimens: A total of 20.1 g of sample and one polished thin section are on deposit at UWS. The main mass is held jointly by Morgan, Abraham, Rose, Curtiss and an anonymous collector.