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Northwest Africa 12562 | |||||||||||||||||||||||||||||||
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Basic information | Name: Northwest Africa 12562 This is an OFFICIAL meteorite name. Abbreviation: NWA 12562 Observed fall: No Year found: 2018 Country: Algeria Mass: ![]() | ||||||||||||||||||||||||||||||
Classification history: |
This is 1 of 138 approved meteorites classified as Achondrite-ung. [show all] Search for other: Achondrites, Ungrouped achondrites | ||||||||||||||||||||||||||||||
Comments: | Approved 31 Aug 2019 | ||||||||||||||||||||||||||||||
Writeup![]() |
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: |
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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) |
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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 1306 approved meteorites from Algeria (plus 30 unapproved names) (plus 4 impact craters) |