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Northwest Africa 12923 | |||||||||||||||||||||||||||
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Basic information | Name: Northwest Africa 12923 This is an OFFICIAL meteorite name. Abbreviation: NWA 12923 Observed fall: No Year found: 2017 Country: Niger Mass: ![]() | ||||||||||||||||||||||||||
Classification history: |
This is 1 of 32 approved meteorites classified as H5-melt breccia. [show all] Search for other: H chondrites, H chondrites (type 4-7), Melted chondrites, Ordinary chondrites, and Ordinary chondrites (type 4-7) | ||||||||||||||||||||||||||
Comments: | Approved 21 Nov 2019 | ||||||||||||||||||||||||||
Writeup![]() |
Writeup from MB 108:
Northwest Africa 12923 (NWA 12923) Niger Purchased: 2017 Classification: Ordinary chondrite (H5, melt breccia) History: Wang Chen and Ziyao Wang purchased many individual specimens totaling 3.4 kg and 2 kg respectively from a Moroccan meteorite dealer during the 2017 Beijing International Mineral, Gem & Fossil Show. Petrography: (C. Herd, UAb) Examination of two ~2 × 4 cm sequential slices and a ~1.5 × 2.5 cm slice (later used to make the thin section) shows dark-gray rounded clasts containing metal and silicates with some microporosity, surrounded by lighter-gray microcrystalline domains which often have vein-like morphology relative to the clasts. Metal grains in the clasts are mostly <0.5 mm, but locally up to 5 mm in longest dimension. At thin section scale, the clasts consist of poorly-delineated chondrules, metal and sulfides in a typical equilibrated ordinary chondrite texture. Microcrystalline domains are glassy in places under optical microscopy. Under the electron microprobe, these domains consist of ~150 μm scale rounded sulfide blebs, and clasts of olivine and low-Ca pyroxene set in a fine-grained matrix of olivine and feldspathic glass; these are likely shock melt veins. Other shock effects include strong mosaicism in olivine. Geochemistry: (C. Herd and L. Tunney, UAb) Data obtained by EMP examination of carbon-coated thin section: Clast Olivine Fa18.7 ± 0.3 (n=10); vein olivine Fa18.3±0.1 (n=3). Low-Ca Pyroxene in clasts Fs16.4±0.4, Wo1.7±0.1 (n=9); vein pyroxene Fs16.1, Wo1.7 (n=1). Clast Feldspar Or3.1Ab75 (n=1). Classification: Ordinary chondrite, H5-melt breccia. Likely paired with Tassedet 004. Specimens: Type specimen of 21.1 g, including one thin section, at UAb. Many stones totaling 3.4 kg with Wang Chen, 2 kg with Ziyao Wang. | ||||||||||||||||||||||||||
Data from: MB108 Table 0 Line 0: |
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Institutions and collections |
UAb: 1-26 Earth Sciences Building, University of Alberta, Edmonton, AB, T6G 2E3, Canada, Canada; Website (institutional address; updated 17 Oct 2011) Beijing: Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China (institutional address; updated 16 Oct 2011) |
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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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Photos: |
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Geography:![]() |
Statistics: This is 1 of 100 approved meteorites from Niger (plus 5 unapproved names) |