Meteoritical Bulletin: Entry for Northwest Africa 6957

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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: 256 g

Classification
history:

Meteoritical Bulletin:	MB 102	(2013)	CR2
Recommended:			CR2 [explanation]

This is 1 of 186 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

help

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 Fa_1.2-5.2, but there are compositions as ferroan as Fa_67.4in the matrix), enstatite (Fs_1.3-1.8Wo_0.6-4.6), diopside (Fs_3.0Wo_39.1; Fs_1.2Wo_42.9). 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:
  MB102
  Table 0
  Line 0:

Place of purchase:	Erfoud
Date:	P 2011 Aug
Mass (g):	256
Pieces:	4
Class:	CR2
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:

Institutions
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, Box 353010 Seattle, WA 98195, United States (institutional address; updated 27 Jul 2012)
OkaU: Institute for Study of the Earth's Interior, Okayama University, Misasa Tottori 682-0193, Japan (institutional address)

Catalogs:

References:

Published in Meteoritical Bulletin, no. 102, MAPS 50, 1662, September 2015

Find references in NASA ADS:
Find references in Google Scholar:

Photos:

Credit	Photos
Photos uploaded by members of the Encyclopedia of Meteorites. (Caution, these are of unknown reliability)
Chris Spratt
Don Cuarzo
Edward Krikorian
Gerald Armstrong
Mirko Graul

Geography:

Coordinates:

Unknown.

Statistics:
This is 1 of 9042 approved meteorites from (Northwest Africa) (plus 1870 unapproved names)

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