Northwest Africa 856

Unknown

Found 2001 March

Martian meteorite (basaltic shergottite)

A single stone of 320 g was found in Morocco in 2001 March. The exact location of find is unknown and the meteorite was referred to under the pseudonym "Djel Ibone". The meteorite has a fine-grained basaltic texture consisting mainly of pyroxene (70 vol%) and maskelynite (23 vol%). Accessory minerals include merrillite, apatite, pyrrhotite, chromite, Fe-Ti oxides, silica (stishovite) and baddeleyite. Melt pockets with phenocrysts and submicrometer-sized needles of stishovite are present. Pyroxenes are highly fractured. Calcite veins formed by terrestrial weathering crosscut the specimens. Classifica­tion and mineralogy (A. Jambon, UPVI; V. Sautter, MNHNP; Ph. Gillet, ENSL): pyroxenes are pigeonite, En48Fs39Wo13, and augite, En36Fs32Wo32; maskelynite composition is An41–47Ab57–51Or2. Geochemistry (J-A. Barrat, UAng and Ch. Göpel, IPGP): bulk composition in wt% is 0.81 TiO2, 6.83 Al2O3, 17.8 FeO*, 0.49 MnO, 9.51 MgO, 10.2 CaO, 1.28 Na2O, 0.13 K2O. Trace elements, 77 ppm Ni and a REE pattern similar to that of Shergotty and Zagami. Key element weight-ratios are FeO*/MnO ≈ 30, Na/Al ≈ 0.40, K/La of 500 and Ga/Al of 4.1 × 10–4. Abundances of Ba and Sr and the Th/U ratio indicate that terrestrial weathering is minor.  Specimens: type specimen, 16 g, ENSL; main mass, Fectay.