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Northwest Africa 12923
Basic information Name: Northwest Africa 12923
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 12923
Observed fall: No
Year found: 2017
Country: Niger
Mass:help 5.5 kg
Classification
  history:
Recommended:  H5-melt breccia    [explanation]

This is 1 of 23 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
Writeuphelp
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:
Place of purchase:Beijing
Date:P 2017
Mass (g):5500
Pieces:many
Class:H5-melt breccia
Fayalite (mol%):18.7±0.3 (n=10)
Ferrosilite (mol%):16.4±0.4 (n=9)
Wollastonite (mol%):1.7±0.1 (n=9)
Classifier:C. Herd and L. Tunney, UAb
Type spec mass (g):21.1
Type spec location:UAb
Main mass:Wang Chen, Ziyao Wang
Comments:Field number MMO-2018-3D; submitted by C. Herd
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)
Catalogs:
References: Published in Meteoritical Bulletin, no. 108, in preparation (2019)
Find references in NASA ADS:
Find references in Google Scholar:
Photos:
CreditPhotos
Photos uploaded by members of the Encyclopedia of Meteorites.
    (Caution, these are of unknown reliability)
Wang Ziyao                  
Geography:

Niger
Coordinates:Unknown.

Statistics:
     This is 1 of 67 approved meteorites from Niger (plus 4 unapproved names)

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