Northwest Africa 14879 (NWA 14879)

(Northwest Africa)

Purchased: 2019 Jul

Classification: Ungrouped achondrite

History: Purchased by Darryl Pitt in July 2019 from a dealer in Erfoud, Morocco.

Physical characteristics: Slices of this specimen reveal that the interior consists of somwhat rounded, coarser grained, khaki-colored regions (up to 1.5 cm across) interspersed with much finer grained, dark brown regions (~30 vol.%).

Petrography: (A. Irving, UWS and P. Carpenter, WUSL) Coarse grained regions or clasts have protogranular texture (mean grainsize ~0.25 mm) and consist predominantly of forsterite and enstatite with accessory diopside, altered Si-bearing kamacite, graphite and a Cr-bearing FeNiP phase. The much finer grained, interstitial regions, which appear to have engulfed portions of the coarser grained lithology, are composed predominantly of finely-exsolved, highly magnesian pyroxene. Sulfides are absent, but secondary calcite, anhydrite and Fe oxides are present

Geochemistry: Forsterite (Fa_0.5-1.0, FeO/MnO = 2-4, N = 4), enstatite (Fs_0.3-1.2Wo_0.8-1.2, FeO/MnO = 1-3, N = 4), subcalcic diopside (Fs_1.2Wo_33.0, FeO/MnO = 7, Al₂O₃ 1.6 wt.%), metal (Ni 5.0±0.0 wt.%, Si 1.6-2.6 wt.%, N = 3). Oxygen isotopes (K. Ziegler, UNM): analyses of acid-washed subsamples by laser fluorination gave, respectively, δ¹⁷O 1.553, 1.581; δ¹⁸O 6.415, 6.519; Δ¹⁷O -1.835, -1.861 per mil (all data linearized).

Classification: Achondrite (ungrouped, magnesian). Paired with NWA 11562 and NWA 12969 based on essentially identical and distinctive textures, mineral compositions and oxygen isotopes.

Specimens: 64.6 g including one polished thin section and a polished endcut at UWB; remainder with DPitt.