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Northwest Africa 7640
Basic information Name: Northwest Africa 7640
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 7640
Observed fall: No
Year found: 2012
Country: (Northwest Africa)
Mass:help 1106 g
Meteoritical Bulletin:  MB 102  (2013)  Brachinite
Recommended:  Brachinite    [explanation]

This is 1 of 55 approved meteorites classified as Brachinite.   [show all]
Search for other: Brachinites, Primitive achondrites
Comments: Approved 14 Nov 2013
Writeup from MB 102:

Northwest Africa 7640 (NWA 7640)

(Northwest Africa)

Purchased: 2012 Nov

Classification: Primitive achondrite (Brachinite)

History: Found purportedly near Zwirat, Mauritania, and purchased by Mohamed Aid in Ouarzazate, Morocc,o in November 2012.

Physical characteristics: A single weathered stone of 1106 g.

Petrography: (A. Irving and S. Kuehner, UWS) Protogranular aggregate of predominantly olivine with lesser clinopyroxene and intermediate plagioclase, plus accessory chromite, altered kamacite and Fe-sulfide (some Ni-bearing). Fine grained intergrowths of iron metal + orthopyroxene occur along olivine grain boundaries. Secondary iron hydroxides are present along grain boundaries.

Geochemistry: Olivine (Fa31.9-32.2, FeO/MnO = 65), augite (Fs9.3-9.7Wo47.9-47.6, FeO/MnO = 36-60).

Classification: Achondrite (brachinite).

Specimens: 20.1 g of material and one polished thin section are at UWB. The remaining material is held by Mr. M. Aid.

Data from:
  Table 0
  Line 0:
Place of purchase:Ouarzazate
Date:P 2012 Nov
Mass (g):1106
Shock stage:low
Weathering grade:moderate
Fayalite (mol%):31.9-32.2
Ferrosilite (mol%):9.3-9.7
Wollastonite (mol%):47.9-47.6
Classifier:A. Irving and S. Kuehner, UWS
Type spec mass (g):20.1
Type spec location:UWB
Main mass:M. Aid
Comments:M12-125; submitted by A. Irving
   and collections
UWS: University of Washington, Department of Earth and Space Sciences, 70 Johnson Hall, Seattle, WA 98195, United States (institutional address; updated 15 Jan 2012)
UWB: University of Washington, Box 353010 Seattle, WA 98195, United States (institutional address; updated 27 Jul 2012)
References: Published in Meteoritical Bulletin, no. 102, MAPS 50, 1662, September 2015
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     This is 1 of 8559 approved meteorites from (Northwest Africa) (plus 1896 unapproved names)

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