Northwest Africa 10132 (NWA 10132)

(Northwest Africa)

Purchased: 2015 Mar

Classification: Ungrouped achondrite

History: Purchased by Darryl Pitt in March 2015 from a dealer in Zagora, Morocco.

Physical characteristics: Single friable stone (940 g) composed of glistening, vitreous yellow-green crystals with minor tiny black grains. Minor brownish weathering occurs on exterior surfaces.

Petrography: (A. Irving and S. Kuehner, UWS) Very fresh specimen with an inequigranular to poikilitic texture. Composed predominantly of orthopyroxene (up to 4.8 mm, some as oikocrysts) and olivine (up to 2 mm, some as chadacrysts within orthopyroxene) with interstitial albitic feldspar (~5 vol.%) and accessory Ti-poor chromite and awaruite.

Geochemistry: Olivine (Fa_53.3-53.5, FeO/MnO = 115-135, NiO = 1.1 wt.%, N = 4), orthopyroxene (Fs_41.6-42.7Wo_3.1-3.4, FeO/MnO = 78-88, Cr₂O₃ = 0.3 wt.%, N = 3), plagioclase (Ab_91.0-92.3An_1.8-2.2Or_7.2-5.6, N = 2). Oxygen isotopes (K. Ziegler, UNM): Analyses of four acid-washed subsamples by laser fluorination gave, respectively, δ¹⁷O 0.893, 1.373, 1.273, 0.857; δ¹⁸O 3.832, 4.702, 4.557, 3.789; Δ¹⁷O -1.130, -1.110, -1.133, -1.144 per mil.

Classification: Achondrite (ungrouped, ultramafic, sodic). This specimen shares many mineralogical similarities with Northwest Africa 6693 and Northwest Africa 6704, but cannot be paired with those specimens based on textural differences and absence of vesicles. The presence of interstitial albite, the elevated Ni in olivine, plus presence of awaruite metal and lack of kamacite are significant differences from lodranites/acapulcoites.

Specimens: 27 g including one polished thin section and one polished thick section at UWB. The remaining material is held by DPitt.