Northwest Africa 1459

Morocco

Purchased 2002 March

Achondrite (diogenite, olivine-bearing)

A small complete stone (49 g) found near Iriqui, Morocco was purchased from a Moroccan dealer by A. and G. Hupé (xHupé) in 2002 March. The interior of the stone is dark yellow-green, and the exterior is coated by a thin, weathered fusion crust with protruding subhedral chromite grains (up to 4 mm). Classification and mineralogy (A. Irving and S. Kuehner, UWS): coarse-grained cataclastic protogranular texture. Subequal amounts of orthopyroxene (Fs₂₈Wo_4.7 to Fs₃₀Wo_6.5, FeO/MnO = 28–32) and olivine (Fa₃₆; FeO/MnO = 46.5), with minor chromite (Cr/(Cr + Al) = 0.62 cores to 0.66 rims), anorthitic plagioclase (Ab_6.8-Ab_9.3), troilite, and metal (0.06 wt% Ni). Some orthopyroxene grains (up to 10 mm)have sparse exsolution lamellae of clinopyroxene (Fs₁₀Wo₄₆ to Fs₁₁Wo₄₅, FeO/MnO = 28–32). Some olivine grains (up to 8 mm) have multiple tilt-boundaries. Irregular areas along grain boundaries are composed of symplectitic intergrowths of chromite and orthopyroxene. Oxygen isotope composition (D. Rumble, CIW): δ¹⁸O = +3.62 ± 0.02‰; δ¹⁷O = +1.72 ± 0.04‰; ∆¹⁷O = -0.19 ± 0.02‰. Specimens: type specimen, 10 g, and one polished thin section, UWS; main mass, xHupé.