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Northwest Africa 11511
Basic information Name: Northwest Africa 11511
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 11511
Observed fall: No
Year found: 2017
Country: Algeria
Mass:help 527 g
Meteoritical Bulletin:  MB 107  (2018)  Ureilite-an
Recommended:  Ureilite-an    [explanation]

This is 1 of 7 approved meteorites classified as Ureilite-an.   [show all]
Search for other: Achondrites, Ureilites
Comments: Approved 12 May 2018
Revised 3 Aug 2018: reclassified using O isotopes
Writeup from MB 107:

Northwest Africa 11511 (NWA 11511)


Purchased: 2017 Jun

Classification: Ureilite (anomalous)

History: Purportedly found near Adrar, Algeria, and purchased by Darryl Pitt in June 2017 from a dealer in Mauritania.

Petrography: (A. Irving and S. Kuehner, UWS) Protogranular aggregate composed predominantly of mafic silicates (orthopyroxene with subordinate olivine, grainsize 0.2-0.7 mm) with accessory sodic plagioclase, tabular graphite and rare schreibersite. Both orthopyroxene and olivine have thin reduced, magnesian rims containing minor blebs of Fe metal.

Geochemistry: Orthopyroxene (Fs10.4-10.5Wo4.5-4.4, FeO/MnO = 13; rim Fs1.1Wo0.4, FeO/MnO = 20; N = 3), olivine (Fa12.6-12.7, FeO/MnO = 22-23; rim Fa6.8, FeO/MnO = 10; N = 3). Oxygen isotopes (K. Ziegler, UNM): analyses of acid-washed subsamples by laser fluorination gave, respectively, d17O 2.018, 1.933, 1.622; d18O 6.632, 6.506, 6.128; D17O -1.484, -1.502, -1.614 per mil.

Classification:Ureilite (anomalous). Originally thought to be an orthopyroxene-rich lodranite. Oxygen isotopes show this graphite-rich achondrite is a ureilite, different from typical ureilites in being orthopyroxene-rich, containing unusually magnesian olivine and most significantly in containing sodic plagioclase.

Specimens: 20.3 g including one polished thin section at UWB; remainder with DPitt.

Data from:
  Table 0
  Line 0:
Place of purchase:Mauritania
Date:P 2017 Jun
Mass (g):527
Shock stage:low
Weathering grade:low
Fayalite (mol%):12.6-12.7
Ferrosilite (mol%):10.4-10.5
Wollastonite (mol%):4.5-4.4
Classifier:A. Irving and S. Kuehner, UWS
Type spec mass (g):20.3
Type spec location:UWB
Main mass:DPitt
Comments:Work name MVCH 296; 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)
UWB: University of Washington, Burke Museum of Natural History and Culture, Box 353010 Seattle, WA 98195, United States (institutional address; updated 9 Oct 2023)
DPitt: Darryl Pitt, 225 West 83rd Street, New York, NY 10024, United States; Website (private address)
References: Published in Meteoritical Bulletin, no. 107, MAPS 55, 460-462
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Public domain photographs:
A. Irving   


     This is 1 of 1315 approved meteorites from Algeria (plus 30 unapproved names) (plus 4 impact craters)

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