Northwest Africa 817 (NWA 817) |
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![]() JPEG (96K) A section cut out of the main mass showing the interior. |
THE METEORITICAL BULLETIN Announcement 85-5, May 23, 2001 Jeffrey N. Grossman, Editor (jgrossman@usgs.gov) Jutta Zipfel, Co-editor for Saharan Meteorites (zipfel@mpch-mainz.mpg.de) Northwest Africa 817 Morocco Found 2000 December Martian meteorite (Nakhlite) A 104 g stone was found in the desert of Morocco. Classification and analysis (V. Sautter, MNHNP; J. Barrat and M. Lesourd, UAng; A. Jambon, UPVI; P. Gillet, ENSL; C. Gvpel and J. Joron, IPGP): an unbrecciated, medium-grained, olivine-bearing clinopyroxenite with cumulate texture; consists of zoned, euhedral, subcalcic augite (Wo38- 40 En38-27Fs24-34 and Fe/Mn = 39-31), olivine (zoned from Fa57 in cores to Fa86 in rims, with Fe/Mn = 54-43) with crystallized magmatic inclusions, and a three-component intercumulus mesostasis (glass including minute amounts of sulfide droplets, Ti-magnetite with unusual skeletal morphology containing ilmenite exsolution, and acicular pyroxene); mineral modes (vol%), pyroxene = 69, olivine = 15, mesostasis = 15, and Fe-Ti oxides = 1; alteration (probably pre- terrestrial) produced a hydrous ferrous silicate both in olivine and in the glassy mesostasis; bulk major-element composition similar to other nakhlites; element ratios confirm Martian origin (FeO*/MnO = 37, Na/Al = 0.40, K/La = 449, Ga/Al = 3.9x10-4); has a higher proportion of mesostasis than other nakhlites; displays the highest Th, U and rare earth elements (REE) concentrations ever reported for a nakhlite (e.g. Th = 0.6 ppm); REE pattern characterized by a strong light REE enrichment (Lan/Ybn = 4.89), and Eu/Eu* = 0.90. Oxygen isotopes (M. Javoy and E. Petit, IPGP): D17O = +0.4 permil. Specimens: 10 g, ENSL; main mass with B. Fectay and C. Bidaut.
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