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Northwest Africa 12562
Basic information Name: Northwest Africa 12562
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 12562
Observed fall: No
Year found: 2018
Country: Algeria
Mass:help 3.93 kg
Classification
  history:
Recommended:  Achondrite-ung    [explanation]

This is 1 of 88 approved meteorites classified as Achondrite-ung.   [show all]
Search for other: Achondrites, Ungrouped achondrites
Comments: Approved 31 Aug 2019
Writeuphelp
Writeup from MB 108:

Northwest Africa 12562 (NWA 12562)

Algeria

Find: 2017

Classification: Ungrouped achondrite

History: A single stone (3930 g), reportedly found in Algeria in 2017, was purchased in Chenzhou, China, by Zuokai Ke in May 2018.

Physical characteristics: Single stone, with a small patch of fusion crust. The surface reveals a fragmental breccia with coarse cream-colored to pale-green grains up to 1 cm in size, crosscut by fine dark veinlets and surrounded by finer-grained light to dark-gray material. Some small clasts are stained by oxidation.

Petrography: (X. Gu, CSUC) The meteorite is composed of brecciated fragments of olivine (85%), pyroxene (8%), and plagioclase (5%), with accessory phases troilite (1%), tridymite (0.4%), chromite(0.3%), and kamacite and taenite (0.2%). The rock-forming minerals are euhedral with grain size generally between 100-800 μm, with some up to several mm. Grains are unzoned. Some material is brecciated to fragments of 10-50 μm. Vermicular chromite-pyroxene symplectites and exsolution lamellae of orthopyroxene-augite are common. Trace alkali feldspar, schreibersite, pentlandite, merrillite, fluorapatite, and ilmenite are observed.

Geochemistry: (X. Gu, CSUC) Plagioclase An2.6-84.6Or0.2-4.7Ab14.8-92.8 (average: An60.6±24.8Or1.6±1.8Ab37.8±23.7, n=85); olivine Fa7.3-94.1 (average Fa17.8±24.0, n=137), Fe/Mn=33.9-64.2 (average=42.9±6.9); low-Ca pyroxene Fs8.0-68.0Wo1.3-8.5 (average Fs29.5±16.4Wo3.5±1.6, n=78), Fe/Mn=21.5-35.6 (average=30.5±2.8); high-Ca pyroxene Fs3.1-65.9Wo9.0-47.2 (average Fs28.4±17.4Wo36.5±10.0, n=42). (Z. Vaci, UNM) Olivine Fa17.0±11.6, Fe/Mn=40±3, n=63; low-Ca pyroxene Fs27.3±10.4Wo4.1±2.4, Fe/Mn=28±1, n=17; high-Ca pyroxene Fs37.9±9.6Wo8.3±6.1, Fe/Mn=27±2, n=7, chromite Al2O3=7.2±4.8, Cr2O3=58.4±6.0, MgO=5.0±1.1, MnO=0.7±0.1, FeO=25.7±2.1 TiO2=0.7±0.4 (wt%), n=6. Oxygen isotopes (K. Ziegler, UNM): 3 acid-washed fragments analyzed by laser fluorination gave δ18O= 3.477, 3.492, 3.795; δ17O= 1.609, 1.619, 1.788; Δ17O= -0.227, -0.225, -0.216 (linearized, all per mil, TFL slope=0.528).

Classification: Ungrouped achondrite, dunite breccia. This meteorite is possibly a polymict breccia in that the dominant mineral fragments are mostly unzoned, but when individually sampled by microprobe analysis display a wide compositional range. The oxygen isotope values of this meteorite plot slightly higher than the eucrite fractionation line (EFL) and are also in the vicinity of the brachinites. The Fe/Mn of this meteorite is somewhat lower than found in HEDs and much lower than in angrites. Unlike most HEDs, it contains alkali feldspar and a wide range of plagioclase compositions. The range in olivine composition in this meteorite is much larger than found in the brachinites and it has much lower Fe/Mn than brachinites. Its mineralogy, oxygen isotopic composition, and secondary features such as Cr-symplectites are similar to the ungrouped dunitic achondrite NWA 12217, but its minerals show a much greater range in major element composition. It is also more extensively brecciated, with heavy fracturing and clast size ranging from μm to cm scale.

Specimens: 21 g including a probe mount on deposit at UNM, Zuokai Ke holds the main mass.

Data from:
  MB108
  Table 0
  Line 0:
Place of purchase:Chenzhou, China
Date:2017
Mass (g):3930
Pieces:1
Class:Achondrite-ung
Shock stage:high
Weathering grade:low
Fayalite (mol%):17.8±24.0
Ferrosilite (mol%):29.5±16.4, 28.4±17.4
Wollastonite (mol%):3.5±1.6, 36.5±10.0
Classifier:X. Gu (CSUC), Z. Vaci, C. Agee (UNM)
Type spec mass (g):21
Type spec location:UNM
Main mass:Ke Zuokai
Comments:Submitted by C. Agee
Plots: O isotopes:  
Institutions
   and collections
UNM: Institute of Meteoritics MSC03 2050 University of New Mexico Albuquerque NM 87131-1126 USA, United States; Website (institutional address; updated 12 Feb 2015)
CSUC: Central South University No.932 South Lushan Road Changsha Hunan 410083, China (institutional address; updated 31 Aug 2019)
Catalogs:
References: Published in Meteoritical Bulletin, no. 108, in preparation (2019)
Find references in NASA ADS:
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Geography:

Algeria
Coordinates:Unknown.

Statistics:
     This is 1 of 978 approved meteorites from Algeria (plus 26 unapproved names) (plus 4 impact craters)

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