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Northwest Africa 6831
Basic information Name: Northwest Africa 6831
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 6831
Observed fall: No
Year found: 2009
Country: (Northwest Africa)
Mass:help 20 g
Classification
  history:
Recommended:  Lunar    [explanation]

This is 1 of 88 approved meteorites classified as Lunar.   [show all]
Search for other: Lunar meteorites
Comments: Approved 10 Mar 2019
Writeuphelp
Writeup from MB 108:

Northwest Africa 6831 (NWA 6831)

(Northwest Africa)

Purchased: 2009

Classification: Lunar meteorite

History: The meteorite was purchased in 2009 from a local meteorite dealer in Erfoud, Morocco.

Physical characteristics: Dark greyish individual without fusion crust.

Petrography: The meteorite is a relatively fine-grained fragmental breccia composed of up to 1 mm sized lithic and mineral clasts consolidated by a vesicular vitreous groundmass. Lithic clasts include basaltic and melt clasts; mineral clasts are dominantly calcic plagioclase, ferroan olivine, low-Ca pyroxene, pigeonite, and Ca-pyroxene. Minor phases include chromite, ilmenite, fayalite, and FeS.

Geochemistry: olivine: Fa40.7±5.5 (Fa31.7-50.4, n=25, FeO/MnO=82-102); low-Ca pyroxene: Fs23.7±0.2Wo3.5±0.3 (Fs23.5-24.0Wo3.2-4.0, n=5, FeO/MnO=55-66); pigeonite: Fs29.3±1.3Wo11.7±2.1 (Fs27.1-31.7Wo8.3-14.8, n=9, FeO/MnO=47-61); Ca-pyroxene: Fs60.7±3.6Wo24.5±2.0 (Fs54.6-67.3Wo20.1-26.9, n=9, FeO/MnO=66-75); calcic plagioclase: An92.6±1.3 (An90.1-93.8, n=20)

Classification: lunar (feldspathic breccia)

Data from:
  MB108
  Table 0
  Line 0:
Place of purchase:Erfoud, Morocco
Date:P 2009
Mass (g):20
Pieces:1
Class:Lunar
Shock stage:moderate
Weathering grade:low
Fayalite (mol%):40.7
Ferrosilite (mol%):23.7; 29.3; 60.7
Wollastonite (mol%):3.5; 11.7; 24.5
Classifier:A. Greshake, MNB
Type spec mass (g):4
Type spec location:MNB
Main mass:Stefan Ralew
Comments:Submitted by Ansgar Greshake
Institutions
   and collections
MNB: Museum für Naturkunde, Invalidenstrasse 43, D-10115 Berlin, Germany (institutional address)
Ralew: Stefan Ralew, Kunibertstraße 29, 12524 Berlin, Germany; Website (private address)
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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