Northwest Africa 3133

Morocco

Purchased 2004 March/August

Primitive achondrite (ungrouped)

Several complete, dense, brown stones (total 2393 g) were purchased in Tagounite by a Moroccan dealer for A. and G. Hupé (xHupé) in 2004 March and August.  Classification and mineralogy (T. Bunch and J. Wittke, NAU; A. Irving and S. Kuehner, UWS): equigranular texture of subhedral to anhedral grains with ~120° triple junctions; mean grain size = 0.28 mm.  Moderate but pervasive weathering (W2) has converted some metal and troilite to brown iron hydroxides, which also coat grain boundaries.  Mineral mode in vol.%: olivine 46, orthopyroxene 28, plagioclase 7, Cr-diopside 5, Na-Mg-bearing merrillite 4, metal (including associated hydroxides) 5, chromite 3 and troilite 2.  Highly equilibrated mineral compositions: olivine (Fa_22.2 to Fa_22.6, FeO/MnO = 57 - 69), orthopyroxene (Fs_18.6Wo_2.8 to Fs_19.2Wo_2.1, FeO/MnO = 38 - 49), diopside (Fs_7.3Wo_44.6 to Fs_8.7Wo_42.2, FeO/MnO = 21 - 33, Cr₂O₃ = 0.56 to 0.82 wt.%, Al₂O₃ =1.21 to 1.74 wt.%), plagioclase (An_50.1Or_2.5 to An_53.5Or_2.3), metal (Ni = 17.4 - 20.2 wt.%), chromite (TiO₂ = 2.61 wt.%, Cr/(Cr+Al) = 0.73), troilite (Ni = 1.2 - 5.2 wt.%).  Oxygen isotopes: replicate analyses of an acid-washed whole rock sample by laser fluorination (D. Rumble, CIW) gave respectively δ¹⁸O = 3.06, 2.46, δ¹⁷O = -1.75, -2.25, Δ¹⁷O = -3.36, -3.54 per mil, and triplicate analyses of an acid-washed olivine-rich separate by laser fluorination (T. Larson and F. Longstaffe, UWO) gave respectively δ¹⁸O = 1.78, 0.92, 0.89, δ¹⁷O = -2.91, -3.67, -3.62, Δ¹⁷O = -3.84, -4.16, -4.08 per mil.  All of these oxygen isotope compositions plot on the CV3 mixing line, suggesting that this achondritic meteorite has affinities with CV chondrites (Irving et al., 2004).  Specimens: type specimens, 20.1 g, and one polished thin section, NAU*; 40.3 g, and four polished thin sections, UWS; main mass, xHupé.