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Northwest Africa 12951
Basic information Name: Northwest Africa 12951
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 12951
Observed fall: No
Year found: 2019
Country: (Northwest Africa)
Mass:help 8.03 kg
Classification
  history:
Recommended:  Winonaite    [explanation]

This is 1 of 37 approved meteorites classified as Winonaite.   [show all]
Search for other: Primitive achondrites, Winonaites
Comments: Approved 7 Nov 2019
Writeuphelp
Writeup from MB 108:

Northwest Africa 12951 (NWA 12951)

(Northwest Africa)

Purchased: 2019 Aug

Classification: Primitive achondrite (Winonaite)

History: Three stones of similar size were purchased by Dr. Albert Jambon in August 2019 from a dealer in Nouakchott, Mauritania.

Physical characteristics: About 80% of the surface of each stone is wind ablated with prominent metal veins and wedges separating depressed silicate regions, but remnant regmaglypts can be discerned. Large exposed metal areas exhibit a visible Widmanstätten pattern as thin, shiny taenite bands separating millimetric kamacite with a greenish oxidized surface. The bottom (formerly buried) sides of the stones are covered with remnants of weathered fusion crust. Fine grained olivine and green pyroxene are observed in places where the crust is missing.

Petrography: (A. Irving, UWS and P. Carpenter, WUSL) Silicate-rich regions of the specimen have a metamorphic, triple grain junction texture (mean grainsize ~150 µm) and are composed of olivine, orthopyroxene, sodic plagioclase, kamacite, taenite and troilite. Cross-cutting metal-rich veins and patches are composed predominantly of kamacite and taenite.

Geochemistry: Olivine (Fa1.1-1.3, FeO/MnO = 3-5, N = 5), orthopyroxene (Fs6.5-6.9Wo1.8-2.1, FeO/MnO = 9-10, N = 4), plagioclase (An14.8-15.4Or3.1-3.4, N = 2). Oxygen isotopes (K. Ziegler, UNM): analyses of acid-washed subsamples by laser fluorination gave, respectively, δ17O 1.969, 2.049, 2.119; δ18O 4.730, 4.887, 5.035; Δ17O -0.528, -0.531, -0.540 per mil.

Classification: Winonaite (metal-veined).

Specimens: 33.3 g including one polished thin section at UWB; remainder with Dr. A. Jambon.

Data from:
  MB108
  Table 0
  Line 0:
Place of purchase:Nouakchott
Date:P 2019 Aug
Mass (g):8029
Pieces:3
Class:Winonaite
Shock stage:low
Weathering grade:low
Fayalite (mol%):1.1-1.3
Ferrosilite (mol%):6.5-6.9
Wollastonite (mol%):1.8-2.1
Classifier:A. Irving, UWS, and P. Carpenter, WUSL
Type spec mass (g):33.3
Type spec location:UWB
Main mass:A. Jambon
Comments:Work name RC115.1; 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)
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)
Catalogs:
References: Published in Meteoritical Bulletin, no. 108, in preparation (2019)
Find references in NASA ADS:
Find references in Google Scholar:
Geography: 
Coordinates:Unknown.

Statistics:
     This is 1 of 7005 approved meteorites from (Northwest Africa) (plus 2002 unapproved names)

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