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Northwest Africa 12777 | |||||||||||||||||||||||||||||
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Basic information | Name: Northwest Africa 12777 This is an OFFICIAL meteorite name. Abbreviation: NWA 12777 Observed fall: No Year found: 2015 Country: (Northwest Africa) Mass: 89.3 g | ||||||||||||||||||||||||||||
Classification history: |
This is 1 of 595 approved meteorites (plus 1 unapproved name) classified as Eucrite. [show all] Search for other: Achondrites, Eucrites, and HED achondrites | ||||||||||||||||||||||||||||
Comments: | Approved 11 Oct 2019 | ||||||||||||||||||||||||||||
Writeup |
Writeup from MB 108:
Northwest Africa 12777 (NWA 12777) (Northwest Africa) Purchased: 2015 Classification: HED achondrite (Eucrite) History: Catalogued at the ROM as sample LM57448. Physical characteristics: Visible fusion crust showing minimal weathering. Interior of the sample shows a pale orange color possibly due to caliche formation. Different clasts visible inside the sample. Petrography: Polymict eucrite breccia containing several clasts, all of which have Opx, Cpx and plagioclase. Matrix is comprised of phenocrysts of pyroxene and plagioclase laths surrounded by fine-graind material of the same composition. Clasts can be described as 1) a very fine grained clast of disequilibrated texture, containing Plag, Opx and Cpx; 2) a lighter clast containing larger plagioclase and pyroxene grains, showing annealed or thermally-metamorphosed texture; 3) several basaltic clasts with needle-shaped plagioclase laths. Whole rock shows severe brecciation and crushing, some clast show more thermal and shock deformation. Geochemistry: Mineral composition and geochemistry: Plagioclase An92.4±3.8 (n=10). Low-Ca pyroxene composition: Fs23.3±9.3Wo4.3±1.2 and Mg# 39.0-70.8 (n=19); High-Ca pyroxene composition: Fs24.9±11.9Wo24.1±17.7, Mg# 38.5-70.2 (n=9) Classification: (A. Cernok, ROM) Texture and compositions suggest the sample is a polymict eucrite breccia. Lack of clear Opx-dominated clasts excludes the possibility of this meteorite being a howardite. | ||||||||||||||||||||||||||||
Data from: MB108 Table 0 Line 0: |
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Institutions and collections |
ROM: Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario M5S 2C6, Canada (institutional address; updated 18 Oct 2011) DGregory: David Gregory, 230 First Avenue, Suite 108, St. Thomas, Ontario N5R 4P5, Canada (private address) |
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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 9589 approved meteorites from (Northwest Africa) (plus 1869 unapproved names) | ||||||||||||||||||||||||||||
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Revision history: |
This lists important revisions made to data for this record.
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