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Northwest Africa 7605 | |||||||||||||||||||||||||||||||
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Basic information | Name: Northwest Africa 7605 This is an OFFICIAL meteorite name. Abbreviation: NWA 7605 Observed fall: No Year found: 2012 Country: (Northwest Africa) Mass: ![]() | ||||||||||||||||||||||||||||||
Classification history: |
This is 1 of 57 approved meteorites classified as Brachinite. [show all] Search for other: Brachinites, Primitive achondrites | ||||||||||||||||||||||||||||||
Comments: | Approved 1 Jan 2013 | ||||||||||||||||||||||||||||||
Writeup![]() |
Writeup from MB 102:
Northwest Africa 7605 (NWA 7605) Northwest Africa Purchased: 2012 Classification: Primitive achondrite (Brachinite) History: Purchased by Stefan Ralew in 2012 from a dealer in Erfoud, Morocco. Physical characteristics: Dark brown, rounded stone with small areas of remnant fusion crust. Interior slices show the rock to be composed of black, interlocking elongate grains with a preferred orientation, plus elongate, lighter gray-colored oikocrysts (up to 15 mm by 5 mm in size). Petrography: (A. Irving and S. Kuehner, UWS) Composed mostly of olivine with subordinate clinopyroxene, Ti-V-bearing chromite, pyrrhotite and rare kamacite, plus large oikocrysts of orthopyroxene + clinopyroxene enclosing ovoid olivine chadacrysts. All mafic silicates exhibit a strongly-oriented grain shape fabric. Intergrowths of pure iron metal + orthopyroxene are present along olivine grain boundaries and along microfractures within olivine grains. Geochemistry: Olivine (Fa26.1-26.2, FeO/MnO = 43-49; chadacrysts in pyroxene Fa24.8-24.9, FeO/MnO = 43-52), orthopyroxene (oikocryst Fs25.8Wo2.5, FeO/MnO = 39, Cr2O3 = 0.2 wt.%; with metal on olivine margins Fs21.8-21.9Wo1.0-2.1, FeO/MnO = 28-30), clinopyroxene (Fs10.2-10.6Wo44.0-47.8, FeO/MnO = 23-31, Al2O3 = 0.7-0.8 wt.%; Cr2O3 = 0.7-0.9.%; oikocryst Fs10.2Wo43.6, FeO/MnO = 32, Al2O3 = 0.7 wt.%, Cr2O3 = 0.7 wt.%). Oxygen isotopes (K. Ziegler, UNM): analysis of an acid-washed sample by laser fluorination gave δ17O = 2.370; δ18O = 4.822; Δ17O = -0.176 per mil. Classification: Brachinite. The mineralogy and oxygen isotopic composition of this specimen are similar to those of other brachinites, but the oriented grain fabric and large pyroxene oikocrysts are unusual. Specimens: A total of 20 g of material and one polished thin section are on deposit at UWB. The main mass is held by Ralew. | ||||||||||||||||||||||||||||||
Data from: MB102 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) Ralew: Stefan Ralew, Kunibertstraße 29, 12524 Berlin, Germany; Website (private address) |
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Catalogs: |
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References: | Published in Meteoritical Bulletin, no. 102, MAPS 50, 1662, September 2015
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Geography: |
Statistics: This is 1 of 9305 approved meteorites from (Northwest Africa) (plus 1873 unapproved names) |