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Northwest Africa 8631
Basic information Name: Northwest Africa 8631
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 8631
Observed fall: No
Year found: 2012
Country: (Northwest Africa)
Mass:help 37 g
Meteoritical Bulletin:  MB 103  (2014)  CO3.0
Recommended:  CO3.0    [explanation]

This is 1 of 22 approved meteorites classified as CO3.0.   [show all]
Search for other: Carbonaceous chondrites, Carbonaceous chondrites (type 3), CM-CO clan chondrites, and CO chondrites
Comments: Approved 25 Nov 2014
Writeup from MB 103:

Northwest Africa 8631 (NWA 8631)

(Northwest Africa)

Purchased: 2012

Classification: Carbonaceous chondrite (CO3.0)

History: Purchased in Erfoud in 2012

Physical characteristics: A single stone partly covered with fusion crust. Cut surface reveals a dark brown interior with small brown-orange chondrules.

Petrography: Chondrules and mineral fragments in a fine grained Fe-rich matrix. Chondrules are mostly of type I, some armored by opaques. Sulfides and metal are found in chondrules and matrix including blebs in the matrix (to 200 μm for metal, to 50 μm for sulfides). Modal abundances (by point counting N=448): matrix 53%, chondrules and mineral fragments 40%, opaques and their weathering products 7% (including ~2% metal, in agreement with magnetic susceptibility). Average chondrule size 240±130 μm (N=67).

Geochemistry: Olivine Fa13.2±17.0 (PMD=118%, Fa0.4-46.9, N=22). Type I chondrules olivine Fa1.0±0.4 (N=14), type II chondrules olivine Fa34.5±9.0 (N=8). Cr2O3 in ferroan olivine is 0.35±0.06 (N=8). Orthopyroxene Fs2.0±0.8Wo1.6±0.9 (Fs1.2-3.3, PMD-FeO=34%, N=5). Magnetic susceptibility log χ =4.65 (χ in 10-9 m3/kg).

Classification: Carbonaceous chondrite (CO3.0). Sub-type from Cr2O3 content of ferroan olivine and olivine Fa range. Matrix abundance is higher and chondrules larger than the usual CO chondrite. Moderate weathering.

Specimens: 7.5 g and a polished section in CEREGE. Main mass with Jean Redelsperger

Data from:
  Table 0
  Line 0:
Place of purchase:Erfoud
Date:P 2012
Mass (g):37
Weathering grade:moderate
Fayalite (mol%):13.2±17.0 (PMD=118%, N=22)
Ferrosilite (mol%):2.0±0.8 (PMD=34%, N=5)
Wollastonite (mol%):1.6±0.9
Magnetic suscept.:4.65
Classifier:J. Gattacceca, CEREGE
Type spec mass (g):7.5
Type spec location:CEREGE
Main mass:Jean Redelsperger
Comments:Submitted by J. Gattacceca
   and collections
CEREGE: CEREGE BP 80 Avenue Philibert, Technopole de l'Arbois 13545 Aix-en-Provence Cedex 4 France, France (institutional address; updated 29 Oct 2018)
References: Published in Meteoritical Bulletin, no. 103, MAPS 52, 1014, May 2017, http://onlinelibrary.wiley.com/doi/10.1111/maps.12888/full
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Photos uploaded by members of the Encyclopedia of Meteorites.
    (Caution, these are of unknown reliability)
Denis gourgues   

     This is 1 of 9116 approved meteorites from (Northwest Africa) (plus 1873 unapproved names)

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