Northwest Africa 8123 (NWA 8123)

(Northwest Africa)

Purchased: 2013 Feb

Classification: H(L)3.1

History: Purchased by Sergey Vasiliev and Marc Jost in February 2013 from a dealer in Erfoud, Morocco.

Petrography: (A. Irving and S. Kuehner, UWS) Well-formed glass-bearing chondrules are set in a heavily stained, metal-bearing matrix.

Geochemistry: Olivine (Fa_0.3-97.1, N = 14; Cr₂O₃ in ferroan examples is 0.12-0.65 wt.%, mean 0.32±0.25 wt.%, N = 12), orthopyroxene (Fs_2.0-12.7Wo_0.5-3.8, N = 3), subcalcic augite (Fs_4.7-24.0Wo_35.4-32.8). Oxygen isotopes (K. Ziegler, UNM): analyses by laser fluorination of acid-washed subsamples gave, respectively δ¹⁷O 2.883, 2.644, 2.289; δ¹⁸O 4.494, 3.478, 3.942; Δ¹⁷O 0.510, 0.808, 0.208 per mil (for a TFL slope of 0.528). Magnetic susceptibility, log χ (× 10^-9 m³/kg) = 4.02.

Classification: Ordinary chondrite H(L)3.1. The wide range in olivine compositions and the distribution of Cr₂O₃ in ferroan olivine establish this specimen as a highly unequilibrated ordinary chondrite of Type 3.1, based on the scheme of Grossman and Brearley (2005). The relatively small average chondrule size and oxygen isotopes appear to establish affinity with H chondrites (despite some scatter in results for acid-washed subsamples of this relatively weathered specimen), but magnetic susceptibility is too low.

Specimens: 24.7 g including one polished thin section at UWB. The remainder is held jointly by Mr. S. Vasiliev and Mr. M. Jost.