Northwest Africa 8171 (NWA 8171)

(Northwest Africa)

Purchased: June 2013

Classification: Martian meteorite (basaltic breccia)

History: Purchased in June 2013 in Ensisheim, France.

Physical characteristics: Nearly completely black 81.88 g stone with remnants of fusion crust. Light-colored clasts and spheroidal objects in a brecciated matrix.

Petrography: (B. Hofmann, NMBE; N. Greber, Bern): Breccia consisting of angular mineral grains (up to 2 mm), lithic clasts (often also breccias) and spheroidal objects (1-3 mm diameter) in fine-grained matrix. Minerals observed are pyroxenes, plagioclase, alkali feldspar, magnetite, ilmenite, pyrite (partially altered to goethite).

Geochemistry: Orthopyroxene (Fs_21.3-45.6Wo_1.9-4.0, FeO/MnO = 27-43; n = 13), pigeonite (Fs_30.9-37.1Wo_6-9, FeO/MnO = 34-42; n = 4), augite (Fs_8.4-29.7, Wo_38-45, FeO/MnO = 13-41; n = 8), plagioclase (An_1.7-52.7Or_1.5-10.5; n = 22), alkali feldspar (An_4.0Or_73.9; n = 4). Bulk analysis (XRF, n=6) gives Fe/Mn (wt) = 46.0±3.4, Ni = 510±56 ppm, Cr = 1485±85 ppm. Oxygen isotopes: (R. Greenwood, OU) gave δ¹⁸O=7.18±0.31, δ¹⁷O=4.41±0.16, Δ¹⁷O= 0.675±0.001 (mean of 2 analyses, all per mil).

Classification: Martian (basaltic breccia). Closely resembles NWA 7034 and pairings and is very likely paired with these stones.

Specimens: 16.50 g including one polished section at NMBE. Remaining material is held by Marc Jost and Beat Booz.