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Northwest Africa 13276
Basic information Name: Northwest Africa 13276
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 13276
Observed fall: No
Year found: 2019
Country: (Northwest Africa)
Mass:help 3.65 kg
Recommended:  Martian (shergottite)    [explanation]

This is 1 of 300 approved meteorites (plus 2 unapproved names) classified as Martian (shergottite).   [show all]
Search for other: Martian meteorites
Comments: Approved 2 May 2020
Writeup from MB 109:

Northwest Africa 13276 (NWA 13276)

(Northwest Africa)

Purchased: 2019 Dec

Classification: Martian meteorite (Shergottite)

History: Four separate but identical-appearing stones were purchased in December 2019 independently by Aziz Habibi (2200 g, 772 g) and Rachid Chaoui (390g, 290 g) from dealers in Mali and Mauritania. Subsequently the 2200 g and 772 g stones were acquired by Darryl Pitt, and the 290 g stone was acquired by Dr. David Gregory.

Physical characteristics: The specimens lack fusion crust. Fresh interiors are relatively coarse grained and exhibit deep brown olivine grains accompanied by pale green pyroxene and sparkling interstitial maskelynite.

Petrography: (A. Irving, UWS and P. Carpenter, WUSL) Poikilitic texture (mean grainsize 0.7 mm). Composed predominantly of compositionally-zoned pyroxene oikocrysts (with domains of pigeonite and subcalcic augite) enclosing chadacrysts of shock-darkened olivine (with limited compositional zoning), accompanied by lath-like maskelynite and accessory Ti-poor chromite, Ti-chromite, ilmenite, merrillite, pyrrhotite, pentlandite and baddeleyite. Melt inclusions are present within olivine grains. Small shock melt pockets are present and minor secondary barite was observed.

Geochemistry: Olivine (Fa33.1-37.1, FeO/MnO = 46-53, N = 14), zoned olivine (core Fa40.4, rim Fa35.2, FeO/MnO = 51-53), pigeonite cores (Fs21.5-22.8Wo3.4-7.6, FeO/MnO = 27-32, N = 7), subcalcic augite cores (Fs15.5-18.5Wo27.6-33.1, FeO/MnO = 25-27, N = 4), pigeonite rims (Fs23.0-30.0Wo8.6-14.0, FeO/MnO = 27-30, N = 7), subcalcic augite rims (Fs15.6-16.4Wo32.5-36.7, FeO/MnO = 23-26, N = 3), maskelynite (An57.5-59.5Or1.6-0.9, N = 6).

Classification: Shergottite (poikilitic).

Specimens: 21.5 g including one polished thin section at UWB; remainder with Mr. A. Habibi, Mr. R. Chaoui and Dr. D. Gregory.

Data from:
  Table 0
  Line 0:
Place of purchase:Mali and Mauritania
Date:P 2019 Dec
Mass (g):3652
Class:Martian (shergottite)
Shock stage:high
Weathering grade:low
Fayalite (mol%):33.1-37.1
Ferrosilite (mol%):21.5-22.8; 15.5-18.5; 23.0-29.9
Wollastonite (mol%):3.4-7.6; 27.6-34.4; 8.6-14.0
Classifier:A. Irving, UWS, and P. Carpenter, WUSTL
Type spec mass (g):21.5
Type spec location:UWB
Main mass:A. Habibi/D. Gregory/R. Chaoui
Comments:Work names AH 737 and RC127.2; 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)
WUSL: Washington Univ., One Brookings Drive, St. Louis, MO 63130, United States (institutional address; updated 17 Oct 2011)
UWB: University of Washington, Box 353010 Seattle, WA 98195, United States (institutional address; updated 27 Jul 2012)
References: Published in Meteoritical Bulletin, no. 109, in preparation (2020)
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     This is 1 of 9368 approved meteorites from (Northwest Africa) (plus 1875 unapproved names)

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