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Northwest Africa 11958
Basic information Name: Northwest Africa 11958
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 11958
Observed fall: No
Year found: 2018
Country: (Northwest Africa)
Mass:help 2.11 kg
Classification
  history:
Meteoritical Bulletin:  MB 107  (2018)  Eucrite-mmict
Recommended:  Eucrite-mmict    [explanation]

This is 1 of 238 approved meteorites classified as Eucrite-mmict.   [show all]
Search for other: Achondrites, Eucrites, and HED achondrites
Comments: Approved 15 Sep 2018
Writeuphelp
Writeup from MB 107:

Northwest Africa 11958 (NWA 11958)

(Northwest Africa)

Purchased: 2018 Feb

Classification: HED achondrite (Eucrite, monomict)

History: Purchased by Bob Falls in February 2018 from a Moroccan dealer at the Tucson Gem and Mineral Show.

Physical characteristics: A single stone (2112 g) composed of greenish beige crystalline clasts (up to 5 cm across) in a patchy, very dark and fine grained matrix.

Petrography: (A. Irving and S. Kuehner, UWS) Breccia consisting of ophitic-textured eucrite clasts in a sparse, dark matrix composed of related crystalline debris within very fine grained quenched melt. Clasts are composed of exsolved pigeonite and calcic plagioclase (both microcrystalline) with accessory silica polymorph, ilmenite, Ti-chromite, troilite, Ni-free metal and minor secondary barite. Cross-cutting veinlets composed of vesicular glass, quenched crystals and entrained eucrite debris are also present.

Geochemistry: Orthopyroxene host (Fs58.3-61.4Wo6.5-3.0, FeO/MnO = 30-31, N = 3), clinopyroxene exsolution lamellae (Fs26.4-29.1Wo44.1-41.6, FeO/MnO = 32-36, N = 2), plagioclase (An86.2-89.8Or0.8-0.2, N = 2).

Classification: Eucrite (monomict breccia, shock melted).

Specimens: 25.5 g in the form of a large polished slice at UWB; remainder with Mr. R. Falls.

Data from:
  MB107
  Table 0
  Line 0:
Place of purchase:Tucson
Date:P 2018 Feb
Mass (g):2112
Pieces:1
Class:Eucrite-mmict
Shock stage:high
Weathering grade:low
Ferrosilite (mol%):58.3-61.4; 26.4-29.1
Wollastonite (mol%):6.5-3.0; 44.1-41.6
Classifier:A. Irving and S. Kuehner, UWS
Type spec mass (g):25.5
Type spec location:UWB
Main mass:R. Falls
Comments:Work name BF18-24; 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)
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, MAPS 55, 460-462
Find references in NASA ADS:
Find references in Google Scholar:
Geography: 
Coordinates:Unknown.

Statistics:
     This is 1 of 7374 approved meteorites from (Northwest Africa) (plus 1957 unapproved names)

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