Northwest Africa 817 (NWA 817) |
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Photo © Bruno Fectay & Carine Bidaut
JPEG (85K)
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Photo © Bruno Fectay & Carine Bidaut
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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