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Northwest Africa 12837
Basic information Name: Northwest Africa 12837
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 12837
Observed fall: No
Year found: 2019
Country: Mali
Mass:help 4.15 kg
Classification
  history:
Meteoritical Bulletin:  MB 108  (2020)  Martian (shergottite)
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 11 Oct 2019
Writeuphelp
Writeup from MB 108:

Northwest Africa 12837 (NWA 12837)

Mali

Purchased: 2019 June

Classification: Martian meteorite (Shergottite)

History: Found in Mali and purchased by Darryl Pitt in June 2019 from a Mauritanian dealer.

Petrography: (A. Irving, UWS and P. Carpenter, WUSL) Cumulate texture. Grains (mean grainsize 0.7 mm) of olivine (some exhibiting undulose extinction) and clinopyroxene (pigeonite and subcalcic augite; some as oikocrysts enclosing small olivine chadacrysts) occur with intercumulus briefringent, twinned plagioclase (~15 vol.%) and accessory Mg-bearing ilmenite, Ti-chromite, pyrrhotite and merrillite. Both olivine and pyroxenes have limited compositional zoning.

Geochemistry: Olivine (Fa34.7-36.8, FeO/MnO = 50-52, N = 4), pigeonite (Fs24.7-30.4Wo4.8-8.6; Fs28.2Wo16.6; FeO/MnO = 28-30, N = 5), subcalcic augite (Fs20.7Wo24.1; Fs17.4-17.8Wo33.7-34.3; FeO/MnO = 24-26, N = 3), plagioclase (An56.9-58.1Or0.8-0.9, N = 2).

Classification: Martian (shergottite, olivine gabbroic, orthocumulate, low shock). Texture, mineralogy and degree of shock are essentially identical to those observed in NWA 12241, with which this material is almost certainly paired. Although the broken pieces of NWA 12241 were purchased in far southern Algeria (close to the border with Mali), there is no assurance that they were found in Algeria, whereas the find location for these newly-studied pieces is reliably established as Mali.

Specimens: 20.4 g including one polished thin section at UWB; remainder with DPitt.

Data from:
  MB108
  Table 0
  Line 0:
Place of purchase:Mauritania
Date:P 2019 June
Mass (g):4147
Pieces:3
Class:Martian (shergottite)
Shock stage:low
Weathering grade:low
Fayalite (mol%):34.7-36.8
Ferrosilite (mol%):24.7-30.4; 17.4-17.8
Wollastonite (mol%):4.8-8.6; 33.7-34.3
Classifier:A. Irving, UWS, and P. Carpenter, WUSL
Type spec mass (g):20.4
Type spec location:UWB
Main mass:D. Pitt
Comments:Work name MVCH 483; submitted by A. Irving
Institutions
   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)
DPitt: Darryl Pitt, 225 West 83rd Street, New York, NY 10024, United States; Website (private address)
Catalogs:
References: Published in Meteoritical Bulletin, no. 108 (2020) Meteorit. Planet. Sci. 55, 1146-1150
Find references in NASA ADS:
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Geography:

Mali
Coordinates:Unknown.

Statistics:
     This is 1 of 100 approved meteorites from Mali (plus 2 unapproved names)

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