Northwest Africa 1068

Morocco

Found 2001 April

Martian meteorite (basaltic shergottite)

In 2001 April, meteorite hunters of the local team of "La Mémoire de la Terre" recovered 23 stones (one large mass, 522 g, and 22 small fragments, <20 g; total known mass, 576.77 g) in the Moroccan Sahara. Rocks are greenish-brown and partially coated by desert varnish; no fusion crust; cracks filled with terrestrial calcium carbonate. Thin shock veins and small melt pockets are abundant. Classification, mineralogy and bulk chemistry (J-A. Barrat, UAng; A. Jambon, UPVI; M. Bohn, I-CB; Ph. Gillet, ENSL; V. Sautter, MNHNP; Ch. Göpel, IPGP; M. Lesourd, SCIAM): consists of olivine (50 µm to 2 mm) in a fine-grained groundmass (average grain size ~100 µm) of euhedral to subhedral pyroxene crystals and interstitial maskelynite; minor phases are chromite, Ti-chromite, ilmenite, ulvöspinel, sulfides, merrillite, apatite, and a K-rich mesostasis; impact melt pockets (up to 1.5 mm long) contain pyrrhotite spherules. Modal abundances of impact melt pockets and calcite free areas: 52 vol% pyroxenes, 22% maskelynite, 21% olivine, 2% phosphates, 2% opaque oxides and sulfides, and 1% K-rich mesostasis. Mineralogy: olivine (Fa₂₈ to Fa₅₈); pyroxenes: pigeonite (En₅₇Wo₅Fs₂₈ to En₄₀Wo₁₃Fs₄₇; fe# (100 Fe/(Fe + Mg) = 29–54 atom%) and augite (En₅₅Wo₂₁Fs₂₄ to En₃₅Wo₂₈Fs₃₆; fe# = 29–51 atom%) are present as separate crystals in roughly equal volume proportions; maskelynite is zoned (An₅₃Ab₄₅Or₂ to An₄₉Ab₄₈Or₃) but is locally An-poor (An₃₅Ab₅₇Or₈); FeO-rich merrillite (FeO 1.3 and 2.8 wt%); apatites, Cl 0.5–2.5 wt% and F 1.1–6.4 wt%; chromite have Ti-rich rims; ulvöspinels contain fine ilmenite lamellae (<1 µm thick). An interstitial K-rich component, probably a shock-produced glass of alkali feldspar and silica, is generally associated with Fe-Ti oxides. Bulk chemistry: Al-poor ferroan basaltic rock, rich in MgO with major element abundances similar to those reported for EETA79001 lithology A.  Key element weight ratios are Fe/Mn = 45, Al/Ti = 6.6, Na/Ti = 1.83, and Na/Al = 0.28.  REE pattern is similar to Shergotty, Zagami, and Los Angeles. Specimens: type specimen, 20 g and 2 polished sections, ENSL; main mass, Fectay.