Hi Bulletin Watchers, One new approval - a shergottite, NWA 7755.
Link - http://www.lpi.usra.edu/meteor/metbull.php?code=57166 Text - Northwest Africa 7755 (NWA 7755) Morocco Purchased: 2013 Classification: Martian meteorite (Shergottite) History: Purchased by Matt Morgan and Lee Morgan in 2013 from a Moroccan meteorite dealer. Physical characteristics: Single stone with black glassy fusion crust, with some light-colored desert sediment coating. A saw cut reveals poikilitic texture. Petrography: (C. Agee, UNM) Microprobe examination of a polished epoxy mount shows ~45% olivine, ~35% pyroxene, ~20% maskelynite, ubiquitous Cr-Ti-Fe oxides. Pyroxenes and olivines are highly equilibrated, with no zonation in BSE images, heavily shocked, grain size ranges from 200-1000 μm. Geochemistry: (C. Agee and L. Burkemper, UNM) EMPA. Olivine Fa38.5±0.8, Fe/Mn=48±2, n=38; pigeonite Fs29.4±1.5Wo10.4±2.4, Fe/Mn=28±1, n=33; augite Fs18.2±1.2Wo34.2±2.4, Fe/Mn=26±2, n=7; maskelynite Or2.3±0.3Ab46.0±2.3An51.6±2.4 N=20. Oxygen Isotopes, laser fluorination (K. Ziegler, UNM), analyses on 3 acid-washed aliquots, 1.5, 1.4, 1.0 mg, gave values δ17O=2.988, 2.882, 2.735; δ18O=5.188, 4.886, 4.696; Δ17O=0.249, 0.302, 0.256 (linearized, all permil). Classification: Achondrite (Martian, shergottite), petrologically equilibrated ultramafic rock, poikilitic shergottite group, with relatively high modal maskelynite, but lacking pyroxene crystallization trends seen in olivine-phyric basaltic shergottites. No known pairings, but pyroxene and olivine compositions are similar to RBT 04262. Specimens: 6 g including microprobe mount on deposit UNM, Matt Morgan holds the main mass. -- ------------------------------------------------------------- Web - http://www.galactic-stone.com Facebook - http://www.facebook.com/galacticstone Twitter - http://twitter.com/GalacticStone Pinterest - http://pinterest.com/galacticstone RSS - http://www.galactic-stone.com/rss/126516 ------------------------------------------------------------- ______________________________________________ Visit the Archives at http://www.meteorite-list-archives.com Meteorite-list mailing list [email protected] http://six.pairlist.net/mailman/listinfo/meteorite-list
