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Northwest Africa 7500
Basic information Name: Northwest Africa 7500
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 7500
Observed fall: No
Year found: 2012
Country: Mali
Mass:help 2.04 kg
Meteoritical Bulletin:  MB 102  (2013)  Martian (shergottite)
Recommended:  Martian (shergottite)    [explanation]

This is 1 of 298 approved meteorites (plus 2 unapproved names) classified as Martian (shergottite).   [show all]
Search for other: Martian meteorites
Comments: Approved 1 Jan 2013
Writeup from MB 102:

Northwest Africa 7500 (NWA 7500)


Purchased: 2012 Mar

Classification: Martian meteorite (Shergottite)

History: Found near Taoudenni, Mali and purchased from the finder by Adam Aaronson in March 2012.

Physical characteristics: A 2040 g, rounded, cuboidal stone almost entirely coated by black glossy fusion crust (which has sloughed off some areas). The interior is medium gray, and exhibits visible sparkling maskelynite intergrown with gray pyroxene.

Petrography: (A. Irving and S. Kuehner, UWS) Very fresh, medium-grained specimen with intersertal texture composed predominantly of prismatic grains of compositionally zoned clinopyroxene and lath-like grains of intermediate plagioclase (maskelynite). Accessory minerals include ilmenite, ulvöspinel, pyrrhotite, fayalite, chlorapatite, merrillite and rare baddeleyite. Quenched melt inclusions within pyroxene consist of K-Al-Si-rich glass, and are surrounded by radial expansion fractures.

Geochemistry: Pyroxene compositions mimic trends shown by Shergotty, with low-Ca varieties (pigeonite) ranging from Fs27.4-61.1Wo10.4-14.0 and high-Ca varieties ranging from Fs19.5-37.0Wo34.5-32.4.

Classification: Martian (shergottite).

Specimens: A total of 23 g of type material and one polished thin section are on deposit at UWB. The main mass is held by Aaronson.

Data from:
  Table 0
  Line 0:
Place of purchase:Temara
Date:P 2012 Mar
Mass (g):2040
Class:Martian (shergottite)
Shock stage:strong
Weathering grade:low
Ferrosilite (mol%):27.4-61.1; 19.5-37.0
Wollastonite (mol%):10.4-14.0; 34.5-32.4
Classifier:A. Irving and S. Kuehner, UWS
Type spec mass (g):23
Type spec location:UWB
Main mass:A. Aaronson
Comments: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)
Aaronson: Sahara Overland Ltd., Harhora, Temara, 12000, Morocco (private address; updated 3 Jan 2010)
References: Published in Meteoritical Bulletin, no. 102, MAPS 50, 1662, September 2015
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     This is 1 of 97 approved meteorites from Mali (plus 2 unapproved names)

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