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Northwest Africa 11729 | |||||||||||||||||||||||||||||||
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Basic information | Name: Northwest Africa 11729 This is an OFFICIAL meteorite name. Abbreviation: NWA 11729 Observed fall: No Year found: 2017 Country: Mauritania Mass: ![]() | ||||||||||||||||||||||||||||||
Classification history: |
This is 1 of 15 approved meteorites classified as Eucrite-an. [show all] Search for other: Achondrites, Eucrites, and HED achondrites | ||||||||||||||||||||||||||||||
Comments: | Approved 7 Apr 2018 | ||||||||||||||||||||||||||||||
Writeup![]() |
Writeup from MB 107:
Northwest Africa 11729 (NWA 11729) Mauritania Purchased: 2017 Dec Classification: HED achondrite (Eucrite, anomalous) History: Purchased by Rachid Chaoui in December 2017 from a Mauritanian dealer and subsequently acquired by Bob Falls. Physical characteristics: A single brownish stone (345 g) mostly coated by black fusion crust. The interior exhibits a breccia texture with beige clasts stained light orange by terrestrial weathering. Petrography: (A. Irving and S. Kuehner, UWS) Breccia composed of closely packed microgabbroic clasts plus some genomict breccia clasts within a sparse matrix of related debris. Minerals are exsolved ferroan pigeonite, calcic plagioclase, silica polymorph, ilmenite Ti-chromite, fayalitic olivine and minor zircon. Terrestrial weathering has resulted in extensive alteration of primary troilite to Fe hydroxides and some cross-cutting hydroxide veinlets. Geochemistry: Orthopyroxene host (Fs69.6Wo1.7, FeO/MnO = 29), clinopyroxene exsolution lamella (Fs33.2Wo42.1, FeO/MnO = 30), clinopyroxene host (Fs30.9Wo43.5, FeO/MnO = 32), orthopyroxene exsolution lamella (Fs69.5Wo1.9, FeO/MnO = 36), fayalite (Fa73.9-74.1, FeO/MnO = 47, N = 2), plagioclase (An82.3-84.3Or0.7-0.5, N = 2). Oxygen isotopes (K. Ziegler, UNM): analyses of acid-washed subsamples by laser fluorination gave, respectively, d17O 2.680,3.062, 2.301; d18O 5.540, 6.312, 4.934; D17O -0.245, -0.271, -0.304 per mil. Classification: Eucrite (anomalous monomict breccia, microgabbroic, highly ferroan). The pyroxenes in this specimen are much more ferroan than in any other known eucrites: ferrosilite contents in orthopyroxene are almost 70 mol.%. The oxygen isotopic composition is also unusual with a higher d18O than other main group eucrites. Specimens: 22.5 g including one polished thin section at UWB; remainder with Mr. R. Falls. | ||||||||||||||||||||||||||||||
Data from: MB107 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) UWS: University of Washington, Department of Earth and Space Sciences, 70 Johnson Hall, Seattle, WA 98195, United States (institutional address; updated 15 Jan 2012) UWB: University of Washington, Box 353010 Seattle, WA 98195, United States (institutional address; updated 27 Jul 2012) |
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Catalogs: |
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References: | Published in Meteoritical Bulletin, no. 107, MAPS 55, 460-462
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Geography:![]() |
Statistics: This is 1 of 200 approved meteorites from Mauritania (plus 2 unapproved names) (plus 2 impact craters) |