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Northwest Africa 12969
Basic information Name: Northwest Africa 12969
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 12969
Observed fall: No
Year found: 2019
Country: (Northwest Africa)
Mass:help 5.83 kg
Recommended:  Achondrite-ung    [explanation]

This is 1 of 119 approved meteorites classified as Achondrite-ung.   [show all]
Search for other: Achondrites, Ungrouped achondrites
Comments: Approved 5 Apr 2020
Writeup from MB 109:

Northwest Africa 12969 (NWA 12969)

(Northwest Africa)

Purchased: 2019 May

Classification: Ungrouped achondrite

History: Purchased by Habib Naji in May 2019 from a dealer in Nouakchott, Mauritania.

Petrography: (A. Irving, UWS and P. Carpenter, WUSL) Composed predominantly of subequal proportions of forsterite (as coarse grained, polygranular agregates up to 4 mm across) and enstatite (also as polygranular aggregates, in part exhibiting polysynthetic twinning). Some enstatite is recrystallized into much finer subgrains, and all is lightly stained by secondary iron hydroxides. Accessory phases include altered Si-bearing kamacite and schreibersite, but no sulfides were observed despite a careful search. Minor secondary barite and calcite are also present.

Geochemistry: Forsterite (Fa1.0±0.0, N = 3), enstatite (Fs0.4-0.7Wo0.9-1.1, N = 3), diopside (Fs0.3Wo38.0), kamacite (Ni 4.8 wt.%, Si 1.7 wt.%). Oxygen isotopes (K. Ziegler, UNM): analyses of acid-washed subsamples by laser fluorination gave, respectively, δ17O = 1.501, 1.727, 1.354; δ18O = 6.280, 6.762, 6.064; Δ17O = -1.815, -1.844, -1.847 per mil.

Classification: Ungrouped achondrite (enstatite-forsterite-rich). This specimen is very unusual in being so olivine-rich, so iron-poor and magnesium-rich, and in evidently containing no sulfides, as well as having an extreme sub-TFL oxygen isotopic composition.

Specimens: 22.5 g including one polished thin section at UWB; remainder with Mr. H. Naji.

Data from:
  Table 0
  Line 0:
Place of purchase:Nouakchott
Date:P 2019 May
Mass (g):5832
Shock stage:low
Weathering grade:low
Fayalite (mol%):1.0±0.0
Ferrosilite (mol%):0.4-0.7; 0.3
Wollastonite (mol%):0.9-1.1; 38.0
Classifier:A. Irving, UWS, and P. Carpenter, WUSL
Type spec mass (g):22.5
Type spec location:UWB
Main mass:H. Naji
Comments:Work name HN-403; submitted by A. Irving
Plots: O isotopes:  
   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)
References: Published in Meteoritical Bulletin, no. 109, in preparation (2020)
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     This is 1 of 8674 approved meteorites from (Northwest Africa) (plus 1882 unapproved names)

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