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Northwest Africa 12474
Basic information Name: Northwest Africa 12474
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 12474
Observed fall: No
Year found: 2003
Country: (Northwest Africa)
Mass:help 957 g
Classification
  history:
Recommended:  CR3    [explanation]

This is the only approved meteorite classified as CR3.
Search for other: Carbonaceous chondrites, Carbonaceous chondrites (type 2), and CR chondrites
Comments: Approved 12 Apr 2019
Writeuphelp
Writeup from MB 108:

Northwest Africa 12474 (NWA 12474)

(Northwest Africa)

Purchased: 2003

Classification: Carbonaceous chondrite (CR3)

Physical characteristics: Dark stone. Cut surface reveals dark interior with chondrules.

Petrography: Chondrite with well-defined chondrules set in an abundant fine-grained matrix (55 vol% from point counting, n=609). Average apparent chondrule diameter 650±310 μm (n=40). Strong weathering. Opaque minerals are FeNi metal, magneite, troilite, often forming composite opaque grains. The chondrules are layered with metal/sulfide rims; opaques are also found blebs up to 300 µm in size, and some metal blebs occur at the surfaces of chondrules. XRD does not show evidence for the presence of phyllosicates. Based on the structural order of the polyaromatic matter assessed by Raman spectroscopy (L. Bonal, IPAG), this meteorite appears slightly metamorphosed, less than Bishunpur (type 3.1). The Raman spectroscopy parameters of interest are FWHM-D (cm-1)=180.3±8.7, ID/IG=0.96±0.04, N=7 (see Bonal et al. 2016, figure 6). Terrestrial weathering is strong with alteration veins croscutting the meteorite.

Geochemistry: Olivine Fa1.9±0.8, PMD=35%, Fa0.5-2.9, Cr2O3=0.4±0.2wt%, (n=5). Low-Ca pyroxene Fs2.4±0.7Wo1.2±0.4, range Fs1.3-3.3Wo0.6-1.8 (n=7). Plagioclase An86.4±2.7Ab13.5±2.8.0Or0.0±0.1 (n=2). Magnetic susceptibility log χ (× 10-9 m3/kg) = 4.69.

Classification: CR3. CR group based on petrography (chondrule size, metal abundance), and geochemistry. Type 3 based on the absence of phyllosilicates; subtype is ~3.1 based on Raman spectroscopy .

Specimens: 29 g and a polished section at CERGEGE. Main mass with Kuntz.

Bibliography:
  • Bonal L., Quirico E., Flandinet L., and Montagnac G. (2016) Thermal history of type 3 chondrites from the Antarctic meteorite collection determined by Raman spectroscopy of their polyaromatic carbonaceous matter. Geochim. Cosmochim. Acta 189 312-337. (link)
Data from:
  MB108
  Table 0
  Line 0:
Place of purchase:France
Date:P 2003
Mass (g):957
Pieces:1
Class:CR3
Weathering grade:high
Fayalite (mol%):1.9±0.8 (n=5)
Ferrosilite (mol%):2.4±0.7 (n=7)
Wollastonite (mol%):1.2±0.4
Magnetic suscept.:4.69
Classifier:L.K. Ruggiu, J. Gattacceca, CEREGE
Type spec mass (g):29.35
Type spec location:CEREGE
Main mass:Fabien Kuntz
Comments:work name K389; submitted by Lisa Krämer Ruggiu
Institutions
   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)
Kuntz: Fabien Kuntz, France; Website (private address)
IPAG: Institut de Planétologie et d’Astrophysique de Grenoble 414, Rue de la Piscine Domaine Universitaire 38400 St-Martin d’Hères , France (institutional address; updated 1 Aug 2013)
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 6781 approved meteorites from (Northwest Africa) (plus 2061 unapproved names)

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