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Northwest Africa 12474 | |||||||||||||||||||||||||||||||
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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: ![]() | ||||||||||||||||||||||||||||||
Classification history: |
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 | ||||||||||||||||||||||||||||||
Writeup![]() |
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, magnetite, 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 crosscutting 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 CEREGE. Main mass with Kuntz. | ||||||||||||||||||||||||||||||
Bibliography: |
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Data from: MB108 Table 0 Line 0: |
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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) |
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Catalogs: |
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References: | Published in Meteoritical Bulletin, no. 108 (2020) Meteorit. Planet. Sci. 55, 1146-1150
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Geography: |
Statistics: This is 1 of 8904 approved meteorites from (Northwest Africa) (plus 1871 unapproved names) |