Northwest Africa 1877

Morocco

Purchased 2003 June

Achondrite (Olivine-rich diogenite)

A partly crusted stony meteorite (312 g) was purchased in Zagora by a Moroccan dealer for A. and G. Hupé (xHupé) in 2003 June and more of the same material (622 g) was purchased in Tagounite in 2003 December. Classification and mineralogy (A. Irving and S. Kuehner, UWS): Coarse grained, dense and somewhat friable, with an overall yellow-green color.  Harzburgitic peridotite composed of subequal amounts of orthopyroxene (Fs_22.4-23.3Wo_1.5; FeO/MnO = 25.2-29.7) and olivine (Fa_27.8, FeO/MnO = 44-50) with minor Al-poor chromite [Cr/(Cr+Al) = 84.8-88.0, Mg/(Mg+Fe) = 11.7-19.8], troilite (as abundant blebs within silicates and as inclusions in chromite), and sparse Ni-free metal (partly altered to limonite).  The modal amount of olivine estimated from three serial thin sections is approximately 45%, which is consistent with the moderately high density of this meteorite. The relatively magnesian silicate compositions are similar to those in Antarctic olivine diogenite GRA 98108, and quite different from those in another Moroccan olivine diogenite NWA 1459 (Irving et al., 2003).  Unlike both of these examples, however, NWA 1877 does not contain plagioclase.  Specimens: type specimen, 24 g and three polished thin sections, UWS; main mass, xHupé.