Northwest Africa 4529

Algeria

Find: September 2006

Achondrite (lodranite)

History: Purchased by Greg Hupé in September 2006 from a Moroccan dealer in Tagounite.

Physical characteristics: A single, dense, dark colored stone (60.0 g) lacking fusion crust.

Petrography: (A. Irving and S. Kuehner, UWS ) The overall texture is coarse-grained (grain size 0.6–1.6 mm) and relatively equigranular, but plagioclase grains (0.2–0.45 mm) are interstitial to other phases. The specimen is composed predominantly of orthopyroxene (with minor clinopyroxene exsolution lamellae) and olivine, with lesser amounts of sodic plagioclase (6.5 vol % ), chromite, clinopyroxene (with minor orthopyroxene exsolution lamellae), Na-Mg-merrillite (grain size up to 0.5 mm), kamacite (some as relatively large grains up to 1.1 mm) and troilite.

Geochemistry: Orthopyroxene (Fs_12.6Wo_2.5, FeO/MnO = 14.7–15.9), olivine (Fa_14.3, FeO/MnO = 24.7–27.1), plagioclase (An_17.8–20.1Or_4.8–3.7), chromite (Cr/(Cr + Al) = 0.853, Mg/(Mg + Fe) = 0.337–0.342, mean TiO₂ = 0.77 wt % ) Oxygen Isotopes (D. Rumble, CIW ): δ¹⁸O (‰) = 3.168, 3.189, 3.467, 2.894; δ¹⁷O = 0.829, 0.757, 0.939, 0.613; Δ¹⁷ O = - 0.837, - 0.920, - 0.884, - 0.909.

Classification: Achondrite (lodranite).

Specimens: A total of 12.0 g and one polished thin section are on deposit at UWS . GHupé holds the main mass.