Northwest Africa 482
Purchased: 2001 January 10
Mass: 1015 g
Lunar meteorite (impact melt breccia)
A 1015 g stone was purchased on 2001 January 10 in Alnif, Morocco, by Michael Farmer. The exact location of find is unknown but it is possibly in Algeria. The stone is complete, oriented, and ap-pears relatively unweathered.
Classification and mineralogy (A. Rubin and P. Warren, UCLA, and D. Kring and I. Daubar, UAz): texture is typical of a crystalline impact melt breccia (polymict) with highland affinities; glassy and vesicular melt veins and melt pockets indicate shock subsequent to compaction by an impact event; plagioclase, An95.7Ab4.09Or0.17 (n = 136, UAz); olivine, Fo65-68 (average Fo66) with FeO/MnO = 88 ± 7 g/g (UCLA); olivine Fo68.4 with FeO/MnO = 93.9 ± 7.7 g/g (range: 78.7 to 111) (n = 51, UAz); pyroxene, Fs25Wo17 with nearly uniform Mg/(Mg+Fe) = 67-68 mol% and FeO/MnO = 51 ± 6 g/g (n = 10, UCLA); pyroxene, Wo10.3- 51En32.6-63.9Fs42.6-14.2, mean Mg/(Mg+Fe) = 68 mol%, FeO/MnO = 52 ± 8 g/g (n = 28, UAz); glassy melt veins occur in both UCLA and UAz samples; a 0.1 mm vein (UCLA) has SiO2 = 44.3 wt.%, Na2O = 0.3 wt.%, Al2O3 = 30.0 wt.%, FeO = 3.6 wr.%, MgO = 3.9 wt.%, CaO = 17.3 wt.%, and TiO2 = 0.3 wt.%, which may approximate the bulk meteorite composition.
Specimens: half of the main mass is with Farmer; type specimens, 24 g, UCLA, and 18 g, UAz.
It’s one of the most beautiful lunar meteorites. It’s one of the few crystalline impact-melt breccias. Compositionally, it’s a typical feldspathic lunar meteorite.
Meteoritical Bulletin Database
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Daubar I. J., Kring D. A., Swindle T. D., and Jull A. J. T. (2002) Northwest Africa 482: A crystalline impact-melt breccia from the lunar highlands. Meteoritics & Planetary Science 37, 1797-1814.
Fischer-Gödde M., Becker H., Wombacher F. (2010) Highly siderophile element abundances and 187Os/188Os in lunar impact melt rocks: Implications for late accretion processes in the Earth-Moon system meteorites. 41st Lunar and Planetary Science Conference, abstract no. 2262.
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Povinec P. P., Sýkora I., Jull A. J. T., Kornoš L., Macke R. J., Porubčan V., and Tóth J. (2019) Aluminium-26 in martian and lunar meteorites: A comparison of cosmic-ray exposure ages. 82nd Annual Meeting of the Meteoritical Society, abstract no. 6309.
Puchtel I. S., Walker R. J., Kring D. A., and James O. B. (2007) Further study of 187Os/188Os and highly siderophile element systematics of lunar impact melt rocks. Lunar and Planetary Science XXXVIII, abstract no. 2040.
Puchtel I. S., Walker R. J., James O. B., and Kring D. A. (2008) Osmium isotope and highly siderophile element systematics of lunar impact melt breccias: Implications for the late accretion history of the Moon and Earth. Geochimica et Cosmochimica Acta 72, 3022-3042.
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