Northwest Africa 2353

Northwest Africa

Purchased 2004

Achondrite (ungrouped)

A stone of 580 g was purchased in Erfoud, Morocco. Description and classification (T. Bunch and J. Wittke, NAU): completely recrystallized into polygonal and subhedral grains; H-group chondrite affinities, but with different oxygen isotopes, no relict chondrules; grain size < 0.5 mm, mean = 0.2 mm; intensely fractured with abundance of subparallel compression fractures. Olivine and pyroxene analyses are within the precision of the electron microprobe. Olivine, Fa_17.9, FeO/MnO = 34; NiO = 0.35 +/- 0.12 wt %; orthopyroxene, Fs_15.6Wo_3.1, FeO/MnO = 19; plagioclase, An_13.1Or_2.6; chromite, cr# = 87; FeS, Ni = 1.65 wt %; metal (taenite only), Ni = 21.6 wt %; troilite, Ni = 1.36 wt % Ni, trace amount of merrillite; magnetite: NiO = 0.27 +/- 0.10 wt%. Oxygen isotope replicate analyses (T. Larson and F. Longstaffe, UWO) of acid-washed, bulk sample by laser fluorination gave δ¹⁷O = 3.16 and 3.3, δ¹⁸O = 5.10 and 5.51, and Δ¹⁷O = 0.44 and 0.51. Weathering grade, W3 and lightly shocked (S2). Specimens: type specimen, 20.1 g, NAU; main mass, Regelman.