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Northwest Africa 6957
Basic information Name: Northwest Africa 6957
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 6957
Observed fall: No
Year found: 2011
Country: (Northwest Africa)
Mass:help 256 g
Meteoritical Bulletin:  MB 102  (2013)  CR2
Recommended:  CR2    [explanation]

This is 1 of 185 approved meteorites classified as CR2.   [show all]
Search for other: Carbonaceous chondrites, Carbonaceous chondrites (type 2), and CR chondrites
Comments: Approved 6 Sep 2013
Writeup from MB 102:

Northwest Africa 6957 (NWA 6957)

(Northwest Africa)

Purchased: 2011 Aug

Classification: Carbonaceous chondrite (CR2)

History: Purchased by Gary Fujihara from a dealer in Erfoud, Morocco in 2011 August.

Petrography: (A. Irving and S. Kuehner, UWS) Separated chondrules with prominent rims of altered kamacite (plus some troilite) set in a dark-brown matrix rich in cronstedtite-tochilinite. Minerals are olivine, enstatite, Cr-Al-bearing diopside, altered kamacite and troilite.

Geochemistry: Olivine (predominantly highly magnesian Fa1.2-5.2, but there are compositions as ferroan as Fa67.4 in the matrix), enstatite (Fs1.3-1.8Wo0.6-4.6), diopside (Fs3.0Wo39.1; Fs1.2Wo42.9). Oxygen isotopes (R. Tanaka, OkaU): analyses of acid-washed subsamples by laser fluorination gave δ17O = -2.642, -3.316; δ18O = 0.355, -0.505; Δ17O = -2.832, -3.055 per mil.

Classification: Carbonaceous chondrite (CR2). The O isotopes together with the low Fa range and presence of cronstedtite-tochilinite make this consistent with a CR.

Data from:
  Table 0
  Line 0:
Place of purchase:Erfoud
Date:P 2011 Aug
Mass (g):256
Shock stage:S2
Weathering grade:W2
Fayalite (mol%):1.2-5.2
Ferrosilite (mol%):1.3-1.8
Wollastonite (mol%):0.6-4.6
Classifier:A. Irving and S. Kuehner, UWS
Type spec mass (g):29
Type spec location:UWB
Main mass:G. Fujihara
Comments:GF11-14; submitted by A. Irving
Plots: O isotopes:  
   and collections
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)
OkaU: Institute for Study of the Earth's Interior, Okayama University, Misasa Tottori 682-0193, Japan (institutional address)
References: Published in Meteoritical Bulletin, no. 102, MAPS 50, 1662, September 2015
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Chris Spratt   
Don Cuarzo   
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     This is 1 of 9776 approved meteorites from (Northwest Africa) (plus 1862 unapproved names)

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