Northwest Africa 3151
Morocco or Algeria
Find: April 2005
History: A 1500 g complete stone with a thin, translucent crust was purchased by G. Hupé in Tagounite, Morocco, in April 2005.
Petrography and Geochemistry: (A. Irving and S. Kuehner, UWS) Coarse-grained dunitic rock (grain size 0.7–1.6 mm) with protogranular texture, composed predominantly of olivine (Fa35.7; FeO/MnO = 81; 95 vol%) with minor clinopyroxene (Fs10.5–10.6Wo44.7–45.2; FeO/MnO = 44; Cr2O3 = 0.65 Al2O3 = 0.95 [both wt%]), altered metal (with some relict taenite), troilite, chromite (Cr/(Cr+Al) = 0.727–0.731) with very rare K-poor, sodic plagioclase (An36.2–39.9Or0.2), and orthopyroxene. Although the silicate minerals are fresh, terrestrial weathering has altered some of the primary metal to hydroxides, which also form thin coatings along grain boundaries. Oxygen isotopes: (D. Rumble, CIW) Replicate analyses of acid-washed whole rock samples by laser fluorination gave δ18O = +4.86 ± 0.03, δ17O = +2.42 ± 0.02, ∆17O = −0.15 ± 0.02 (all ‰).
Classification: Achondrite (brachinite).
Specimens: A 20 g type specimen and one polished thin section are on deposit at UWS. GHupé holds the main mass.