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Northwest Africa 12241
Basic information Name: Northwest Africa 12241
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 12241
Observed fall: No
Year found: 2018
Country: Algeria
Mass:help 1150 g
Classification
  history:
Recommended:  Martian (shergottite)    [explanation]

This is 1 of 176 approved meteorites (plus 1 unapproved name) classified as Martian (shergottite).   [show all]
Search for other: Martian meteorites
Comments: Approved 24 Nov 2018
Writeuphelp
Writeup from MB 107:

Northwest Africa 12241 (NWA 12241)

Algeria

Purchased: 2018 Aug

Classification: Martian meteorite (Shergottite)

History: Purportedly found in Algeria and purchased by Mohamed Brahim Sueilem in August 2018 from a dealer in Bordj Badji Mokhtar, Algeria.

Physical characteristics: The material (total weight 1150 g) comprises multiple broken fragments, some with adhering black fusion crust. The friable pieces are pale green in color and contain white plagioclase but no evident maskelynite.

Petrography: (A. Irving and S. Kuehner, UWS) This fresh specimen has an orthocumulate texture with ~15 vol.% lath-like, birefringent plagioclase occurring interstitially to more abundant and coarser grained (0.2-1.6 mm, mean 0.7 mm) mafic silicate grains (unzoned olivine and patchily zoned low-Ca and high-Ca clinopyroxene with very limited compositional variation). Accessory phases include Mg-merrillite, chlorapatite, ilmenite, Ti-rich chromite, Cr-rich chromite and pyrrhotite (some associated with minor pentlandite). Levels of shock are judged to be low, based on the absence of optical effects in plagioclase and the complete lack of any conversion to maskelynite; the presence of widespread microcracks in mafic silicates is the only clear evidence of shock.

Geochemistry: Olivine (Fa32.7-34.3, FeO/MnO = 47-48, N = 4), pigeonite (Fs25.0-30.4Wo5.5-10.0, FeO/MnO = 28-30, N = 4), subcalcic augite (Fs17.1-18.1Wo32.7-32.4, FeO/MnO = 23-25, N = 2), aluminous augite inclusion in olivine (Fs17.1Wo39.5, FeO/MnO = 28, TiO2 = 1.1 wt.%, Al2O3 = 6.2 wt.%), plagioclase (An43.0-57.8Or2.4-1.3, N = 3). Oxygen isotopes (K. Ziegler, UNM): analyses of acid-washed subsamples by laser fluorination gave, respectively, δ17O 2.907, 2.635, 2.808; δ18O 5.092, 4.620, 4.875; Δ17O 0.218, 0.195, 0.234 per mil.

Classification: Martian (shergottite, olivine gabbroic, orthocumulate, low shock).

Specimens: 22.4 g including one polished thin section at UWB; remainder held jointly by Naji Ben Faraji and Mohamed Brahim Sueilem.

Data from:
  MB107
  Table 0
  Line 0:
Place of purchase:Bordj Badji Mokhtar, Algeria
Date:P 2018 Aug
Mass (g):1150
Pieces:many
Class:Martian (shergottite)
Shock stage:low
Weathering grade:low
Fayalite (mol%):32.7-34.3
Ferrosilite (mol%):25.0-30.4; 17.1-18.1
Wollastonite (mol%):5.5-10.0; 32.7-32.4
Classifier:A. Irving and S. Kuehner, UWS
Type spec mass (g):22.4
Type spec location:UWB
Main mass:N. Faraji and M. Sueilem
Comments:Work name ML18-1; submitted by A. Irving
Plots: O isotopes:  
Institutions
   and collections
UNM: Institute of Meteoritics MSC03 2050 University of New Mexico Albuquerque NM 87131-1126 USA, United States; Website (institutional address; updated 12 Feb 2015)
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)
Catalogs:
References: Published in Meteoritical Bulletin, no. 107, in preparation (2018)
Find references in NASA ADS:
Find references in Google Scholar:
Geography:

Algeria
Coordinates:Unknown.

Statistics:
     This is 1 of 941 approved meteorites from Algeria (plus 26 unapproved names) (plus 4 impact craters)

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