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Northwest Africa 12690
Basic information Name: Northwest Africa 12690
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 12690
Observed fall: No
Year found: 2019
Country: (Northwest Africa)
Mass:help 9.1 kg
Meteoritical Bulletin:  MB 108  (2020)  Martian (shergottite)
Recommended:  Martian (shergottite)    [explanation]

This is 1 of 284 approved meteorites (plus 2 unapproved names) classified as Martian (shergottite).   [show all]
Search for other: Martian meteorites
Comments: Approved 18 Aug 2019
Writeup from MB 108:

Northwest Africa 12690 (NWA 12690)


Find: 2018 Dec

Classification: Martian meteorite (Shergottite)

History: The meteorite was reportedly found December 16, 2018, by a Malian nomad near Achemeleml and purchased in 2019 by Ben Hoefnagels in Niger. One fragment was analyzed by Ansgar Greshake at MNB and the analysis of a second fragment was initiated by Ben Hoefnagels and conducted by Paul Carpenter, WUSTL.

Physical characteristics: Large greenish individual with some fusion crust.

Petrography: The meteorite has a diabasic texture and is predominantly composed of up to 3 mm sized calcic pyroxenes that show complex patchy compositional zoning and equally sized maskelynite grains. Minor phases include ilmenite, ulvospinel, merrillite, and pyrrhotite. Some myrmekitic breakdown assemblages consisting of Fe-rich pyroxene, fayalite, and silica are present. The meteorite is highly shocked and contains abundant shock melt pockets.

Geochemistry: (A. Greshake, MNB) pigeonite: Fs53.2±18.9Wo13.6±2.6 (Fs27.2-76.2Wo8.9-18.1, n=26, FeO/MnO=26-42); augite: Fs28.5±4.4Wo28.7±5.9 (Fs24.5-37.1Wo20.8-35.2, n=15, FeO/MnO=26-34); maskelynite: An62.3Ab37.4Or0.3, n=22; P. Carpenter (Washington University, St. Louis) Ca-pyroxene cores: Wo24.8-35.0En42.2-49.2Fs21.0-26.2, N=3, FeO/MnO 28-30; Ca-pyroxene rims: Wo14.7-40.3En2.3-19.6Fs57.4-72.0, N=3, FeO/MnO 38-43; fayalite: Fa96.5, N=1, maskelynite: An61.4Ab38.4Or0.2, N=1.

Classification: Martian (diabasic shergottite)

Specimens: 34.4 g are at MNB and 14.36 g are at UWB; 20 g with Mr. B. Hoefnagels. Main mass with anonymous owner.

Data from:
  Table 0
  Line 0:
Place of purchase:Niger
Date:2018 Dec
Mass (g):9095
Class:Martian (shergottite)
Shock stage:high
Weathering grade:low
Ferrosilite (mol%):53.2; 28.5
Wollastonite (mol%):13.6; 28.7
Classifier:A. Greshake, MNB
Type spec mass (g):48.8
Type spec location:MNB; UWB
Main mass:anonymous
Comments:Work names AB-1-2019, BH206; submitted by Ansgar Greshake
   and collections
MNB: Museum f├╝r Naturkunde, Invalidenstra├če 43, D-10115 Berlin, Germany (institutional address; updated 24 Dec 2011)
UWB: University of Washington, Box 353010 Seattle, WA 98195, United States (institutional address; updated 27 Jul 2012)
References: Published in Meteoritical Bulletin, no. 108 (2020) Meteorit. Planet. Sci. 55, 1146-1150
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Public domain photographs:
Ansgar Greshake         

     This is 1 of 8674 approved meteorites from (Northwest Africa) (plus 1882 unapproved names)

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