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Northwest Africa 12445
Basic information Name: Northwest Africa 12445
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 12445
Observed fall: No
Year found: 2018
Country: (Northwest Africa)
Mass:help 797 g
Recommended:  Eucrite-an    [explanation]

This is 1 of 15 approved meteorites classified as Eucrite-an.   [show all]
Search for other: Achondrites, Eucrites, and HED achondrites
Comments: Approved 21 Mar 2020
Writeup from MB 109:

Northwest Africa 12445 (NWA 12445)

(Northwest Africa)

Purchased: 2018 Aug

Classification: HED achondrite (Eucrite, anomalous)

History: A total of 21 similar stones (total 797 g) were recovered ~70 m apart at a location in Algeria, and were purchased by Mbark Arjdal in August 2018 from an Algerian dealer.

Petrography: (A. Irving and S. Kuehner, UWS) Breccia composed of some lithic eucrite clasts plus a lot of related, angular crystalline debris in a finer grained matrix. Lithic clasts have microgabbroic to subophitic textures. Minerals are exsolved pigeonite (pale orange in thin section), anorthite (exhibiting undulose extinction), silica polymorph, fayalite, ilmenite, troilite and minor Ni-free metal.

Geochemistry: Low-Ca pyroxene host (Fs67.7±1.6Wo3.1±1.3, range Fs66.0-70.6Wo1.7-5.3, FeO/MnO = 29-31, N = 6; Fs59.7Wo2.4, FeO/MnO = 28), high-Ca pyroxene exsolution lamellae (Fs32.1±2.0Wo42.8±0.7, range 29.2-34.4Wo42.0-43.7, FeO/MnO = 30-33, N = 6; Fs24.7-25.9Wo44.5-42.9, FeO/MnO = 29-30, N = 2), fayalitic olivine (Fa73.8±6.5, range Fa69.3-78.4, FeO/MnO = 46, N = 2), anorthite (An91.9-93.3Or0.6-0.3, N = 2).

Classification: Eucrite (breccia, anomalous). The predominance of highly ferroan low-Ca and high-Ca pyroxenes in this specimen is an anomalous feature; these now-exsolved highly ferroan pigeonites are reminiscent of similar pyroxenes in anomalous ferroan eucrite NWA 11729.

Specimens: 38.2 g including one polished thin section at UWB; remainder with Mr. M. Arjdal.

Data from:
  Table 0
  Line 0:
Place of purchase:Algeria
Date:P 2018 Aug
Mass (g):797
Shock stage:moderate
Weathering grade:low
Fayalite (mol%):73.8±6.5 (N=2)
Ferrosilite (mol%):67.7±1.6 (n=6)
Wollastonite (mol%):3.1±1.3
Classifier:A. Irving and S. Kuehner, UWS
Type spec mass (g):38.2
Type spec location:UWB
Main mass:M. Arjdal
Comments:Work name Arj18-A10; 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)
References: Published in Meteoritical Bulletin, no. 109, in preparation (2020)
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Public domain photographs:
A. Irving   

     This is 1 of 9111 approved meteorites from (Northwest Africa) (plus 1873 unapproved names)

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