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Northwest Africa 13955
Basic information Name: Northwest Africa 13955
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 13955
Observed fall: No
Year found: 2020
Country: Algeria
Mass:help 1760 g
Classification
  history:
Recommended:  Achondrite-ung    [explanation]

This is 1 of 106 approved meteorites classified as Achondrite-ung.   [show all]
Search for other: Achondrites, Ungrouped achondrites
Comments: Approved 8 Jun 2021
Writeuphelp
Writeup from MB 110:

Northwest Africa 13955 (NWA 13955)

Algeria

Find: 2020

Classification: Ungrouped achondrite

History: A single 1760 g stone was recovered by a group of Saharawi meteorite hunters in the Algerian part of the Erg Chech region during the summer of 2020, and then purchased by Ali Salamu from a dealer in Nouadhibou, Mauritania.

Physical characteristics: The interior of the specimen has an overall light brown color with small orange patches, and contains sporadic smooth-walled vesicles.

Petrography: (A. Irving, UWS and P. Carpenter, WUSL) Cumulate with pyroxene, olivine and intercumulus calcic plagioclase. Composed of subhedral grains of olivine (~20 vol.%) and low-Ca pyroxene (~70 vol.%, zoned from small orthopyroxene cores to thick mantles of pigeonite) together with intercumulus calcic plagioclase (<10 vol.%) and accessory chromite (low-Ti to Ti-free), metal with (Fe/Ni ratios intermediate between those for typical typical kamacite and taenite), and Fe oxide (possibly representing altered sulfide). Sporadic vesicles or vugs are present.

Geochemistry: Olivine (Fa33.8-34.8, FeO/MnO = 41-44, N = 4), orthopyroxene cores (Fs19.1-20.5Wo0.7-0.8, FeO/MnO = 29-30, N = 2), low-Ca pyroxene (Fs26.8-27.6Wo3.4-5.2, FeO/MnO = 26-28, N = 3), pigeonite (Fs25.1-26.7Wo7.7-7.8, FeO/MnO = 28-29, N = 2), plagioclase (An79.9-86.3Or1.1-0.5, N = 3). Oxygen isotopes (K. Ziegler, UNM): analyses of acid-washed subsamples by laser fluorination gave, respectively, δ17O 1.716, 1.777, 1.725; δ18O 3.828, 3.873, 3.782; Δ17O -0.305, -0.268, -0.272 (all data linearized).

Classification: Ungrouped achondrite (ultramafic, vesicular). The meteorite is different from diogenites with orthopyroxene present as cores only, and predominance of pigeonite. The oxygen isotopic composition plots below the for diogenites and typical eucrites.

Specimens: 20.7 g including one polished thin section at UWB; remainder with Mr. A. Salamu.

Data from:
  MB110
  Table 0
  Line 0:
Place of purchase:Nouadhibou
Date:2020
Mass (g):1760
Pieces:1
Class:Achondrite-ung
Shock stage:low
Weathering grade:low
Fayalite (mol%):33.8-34.8
Ferrosilite (mol%):19.1-27.6; 25.1-26.9
Wollastonite (mol%):0.8-4.4; 5.2-7.8
Classifier:A. Irving, UWS, and P. Carpenter, WUSL
Type spec mass (g):20.7
Type spec location:UWB
Main mass:A. Salamu
Comments:Work name SAL21-09; 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. 110, in preparation (2021)
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Photos:
CreditPhotos
Public domain photographs:
A. Irving   
Geography:

Algeria
Coordinates:Unknown.

Statistics:
     This is 1 of 1110 approved meteorites from Algeria (plus 27 unapproved names) (plus 4 impact craters)

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