Northwest Africa 4223

Algeria

Find: December 2005

Achondrite (diogenite, olivine-bearing)

History: G. Hupé purchased the stones in December 2005 in Tagounite, Morocco.

Physical characteristics: The meteorite comprises two dense, dark brown and partly fusion crusted stones with a total weight of 329 g.

Petrography: (A. Irving and S. Kuehner, UWS) The meteorite is coarse-grained (≤ 4 mm) with a primarily protogranular texture, and some areas of cataclasis. Olivine (50 vol%) and orthopyroxene (45 vol% ) are the dominant minerals with accessory chromite, troilite and metal (kamacite). Some veinlets of terrestrial calcite crosscut the specimen.

Mineral compositions and geochemistry: Olivine (Fa_30.0-31.2; FeO/MnO = 44.8-48.2), orthopyroxene (Fs_24.2-25.2Wo_2.8-3.2; FeO/MnO = 28.8), chromite (Cr/(Cr+Al) = 0.703-0.715; Fe/(Fe+Mg) = 0.69-0.73, mean TiO₂ = 1.02 wt%).Oxygen Isotopes: (D. Rumble, CIW) Analyses of two aliquots by laser fluorination gave, respectively, δ¹⁸O = 3.08, 3.22; δ¹⁷O = 1.44, 1.48; Δ¹⁷O = -0.180, -0.214 (all ‰).

Classification: Achondrite (diogenite, olivine-bearing).

Type specimens: A total of 20.4 g of sample, one polished thin section and a polished mount are on deposit at UWS. Hupé holds the main mass.