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Northwest Africa 12438 | |||||||||||||||||||||||||||||||
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Basic information | Name: Northwest Africa 12438 This is an OFFICIAL meteorite name. Abbreviation: NWA 12438 Observed fall: No Year found: 2007 Country: (Northwest Africa) Mass: 14.4 g | ||||||||||||||||||||||||||||||
Classification history: |
This is 1 of 149 approved meteorites classified as Achondrite-ung. [show all] Search for other: Achondrites, Ungrouped achondrites | ||||||||||||||||||||||||||||||
Comments: | Approved 11 Jun 2019 | ||||||||||||||||||||||||||||||
Writeup |
Writeup from MB 108:
Northwest Africa 12438 (NWA 12438) (Northwest Africa) Purchased: 2007 Classification: Ungrouped achondrite History: Catalogued at the ROM under M58154. Physical characteristics: Single stone with a black regmaglypted fusion crust over the exterior. Petrography: (T.V. Kizovski, ROM) This specimen exhibits a proto-granular texture and is predominantly comprised of euhedral magnesian olivine (60%), with equal amounts of low and high-Ca pyroxenes (39%). Fe-metal fills the grain boundaries between all silicate phases. No feldspar or chondrules are present. The olivine grains vary in size from approximately 300 to 700 µm, and pyroxene grains vary in size from 550 to 800 µm. The stone shows signs of moderate desert weathering, with approximately 60% of metal oxidized. Extensive fracturing is observed in olivine and pyroxene grains with some pyroxenes exhibiting undulatory extinction. Geochemistry: Mineral compositions and geochemistry: (Y.Liu, UTorG; T.V. Kizovski, ROM) Olivine (Fa3.9±0.6; Fe/Mn = 16.1±2.7; n=27), high-Ca pyroxene (Fs2.7±1.8Wo36.7±0.8; Fe/Mn = 9.1±6.4; n=25), low-Ca pyroxene(Fs4.5±3.1Wo4.3±1.0; Fe/Mn = 13.5±10.0; n=18). Oxygen isotopes (K. Ziegler, UNM): analyses of acid-washed subsamples by laser fluorination gave δ17O = -1.336,-1.469,-1.531; δ18O = 0.943, 0.720, 0.592; Δ17O = -1.834, -1.849, -1.844 per mil. This sample is texturally and chemically similar to ungrouped achondrite NWA 8054, and they may be paired. Classification: (T.V. Kizovski, ROM) Achondrite (ungrouped) Specimens: 3.01 g specimen including a thin section and smaller fragments at the ROM. D. DGregory holds the 11.35 g main mass. | ||||||||||||||||||||||||||||||
Data from: MB108 Table 0 Line 0: |
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Plots: | O isotopes: | ||||||||||||||||||||||||||||||
Institutions and collections |
ROM: Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario M5S 2C6, Canada (institutional address; updated 18 Oct 2011) UNM: Institute of Meteoritics MSC03 2050 University of New Mexico Albuquerque NM 87131-1126 USA, United States; Website (institutional address; updated 12 Feb 2015) DGregory: David Gregory, 230 First Avenue, Suite 108, St. Thomas, Ontario N5R 4P5, Canada (private address) UTorG: University of Toronto, Dept. Geology, Earth Sciences Centre, 22 Russell Street Toronto, Ontario, M5S 3B1, Canada (institutional address; updated 31 Jan 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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Geography: |
Statistics: This is 1 of 9627 approved meteorites from (Northwest Africa) (plus 1865 unapproved names) | ||||||||||||||||||||||||||||||
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Revision history: |
This lists important revisions made to data for this record.
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