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Northwest Africa 773 | |||||||||||||||||
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Basic information | Name: Northwest Africa 773 This is an OFFICIAL meteorite name. Abbreviation: NWA 773 Observed fall: No Year found: 2000 Country: Western Sahara Mass: ![]() | ||||||||||||||||
Classification history: |
This is 1 of 13 approved meteorites classified as Lunar (gabbro). [show all] Search for other: Lunar meteorites | ||||||||||||||||
Comments: | Revised 12 Feb 2023: updated classification | ||||||||||||||||
Writeup![]() |
Writeup from MB 85:
Northwest Africa 773 Western Sahara Found 2000 September Lunar Meteorite (cumulate olivine norite with regolith breccia) Three stones of 359, 224 and 50 g, totaling 633 g were sold to Marvin Killgore (SWML) by nomads who showed him the place of find on a flat dry desert plain near Dchira, Western Sahara. Mineralogy and classification (T. Fagan, UHaw; M. Killgore, SWML; J. Wittke and T. Bunch, NAU): consists of two distinct lithologies, cumulate rock and regolith breccia; shock stage, S2; weathering grade, W1. Cumulate portion: modes (vol%) are olivine = 54.7, pigeonite = 24.2, augite = 5, feldspar (including minor K-feldspar) = 15.6, opaques (troilite, chromite, Fe-metal, ilmenite) = 0.5; olivine, Fa28–34, mean Fa31, FeO/MnO = 99 ± 11 g/g; pigeonite, En64Wo11, FeO/MnO = 53 ± 6 g/g; augite, En49Wo36, FeO/MnO = 46 ± 6 g/g; plagioclase, An88–91; Ba-rich K-feldspar, An3Ab4Or93 with average BaO = 2.2 wt%. Breccia portion: contains fragments of cumulate portion as well as silica glass, hedenbergitic pyroxene, volcanic rocks, and unusual lithic clasts with fayalite + Ba-rich K-feldspar + silica + plagioclase; olivine and pyroxene in the breccia have a slightly wider compositional range towards lower Mg/(Mg + Fe) than in the cumulate portion of the rock. Chemical composition (D. Mittlefehldt, JSC): KREEP-rich with strong negative Eu-anomaly. Noble gases (O. Eugster, Physikalisches Institut, Bern): high solar wind component, 4He/20Ne = 9, indicative of regolith material. Specimens: type specimen, 15 g, NHM; main mass SWML. Writeup from MB 112: NWA 773: classification update
From A. Irving, UWS: Based on Fagan et al. (2003) and many subsequent pairings (see Crosslinks section on this page), NWA 773 should be classified as a gabbro instead of a norite. | ||||||||||||||||
Bibliography: |
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Data from: MB85 Table 4 Line 213: |
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Institutions and collections |
JSC: Mailcode XI, 2101 NASA Parkway, NASA Johnson Space Center, Houston, TX 77058, United States; Website (institutional address; updated 28 Jul 2022) NAU: Geology, Bldg 12 Knoles Dr Northern Arizona University, Flagstaff, AZ 86011, United States; Website (institutional address; updated 12 Apr 2012) NHM: Department of Mineralogy, The Natural History Museum, Cromwell Road, London SW7 5BD, United Kingdom; Website (institutional address; updated 9 Dec 2011) UWS: University of Washington, Department of Earth and Space Sciences, 70 Johnson Hall, Seattle, WA 98195, United States (institutional address; updated 15 Jan 2012) Bern: University of Bern, University of Bern, Hochschulstrasse 4, CH-3012 Bern, Switzerland (institutional address) Killgore: Marvin and Kitty Killgore, Southwest Meteorite Laboratory, P.O. Box 95, Payson, AZ 85547, United States; Website (private address) SWML: Marvin and Kitty Killgore, Southwest Meteorite Laboratory, P.O. Box 95, Payson, AZ 85547, United States; Website (private address) UHaw: Hawai'i Institute of Geophysics and Planetology, School of Ocean and Earth Science and Technology, University of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, United States (institutional address; updated 25 Oct 2011) |
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Catalogs: |
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References: | Published in Meteoritical Bulletin, no. 85, MAPS 36, A293-A322 (2001) Published in Meteoritical Bulletin, no. 112, in preparation (2023)
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Geography:![]() |
Statistics: This is 1 of 108 approved meteorites from Saguia el Hamra, Western Sahara (plus 1 unapproved name) This is 1 of 270 approved meteorites from Western Sahara (plus 20 unapproved names) | ||||||||||||||||
Proximity search: |