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Lunar Meteorite: Northwest Africa (NWA) 4884northern Africa |
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from The
Meteoritical Bulletin,
no. 93, Meteoritics & Planetary Science 43,
571-632 (2007)Northwest Africa 4884Northwest AfricaFind: July 2007 Achondrite (lunar, mingled basalt-rich breccia) History: Purchased by Greg Hupé in July 2007 from a dealer in Tagounite, Morocco. Physical characteristics: A single stone (42 g) partially covered by black fusion crust; interior slices show it to be a breccia composed of white, beige and light gray clasts in a dark gray matrix (see image). Petrography: (A. Irving and S. Kuehner, UWS) Regolithic breccia composed of abundant angular mineral and lithic clasts in a sparse vesicular, glassy matrix. Mineral fragments include calcic plagioclase, pigeonite, augite, Ti-chromite, ilmenite (one with a tiny baddeleyite inclusion) and silica polymorph. Lithic clasts include several types of mare basalt (a coarse-grained example is composed of olivine+zoned pigeonite+calcic plagioclase+ilmenite+troilite), granophyric intergrowths of Fe-rich augite+fayalitic olivine+silica polymorph, a coarse grained dunitic or troctolitic rock containing a large metal grain (associated with rutile and secondary ilmenite), and a large “breccia-within-breccia” clast. Mare basalt clasts and debris are predominant over highlands lithologies. Geochemistry: Olivine clasts (Fa37.0-37.7; FeO/MnO = 94-98), olivine in basalt clast (Fa87.9; FeO/MnO = 89), plagioclase (An92.4-95.3Or0.5-0.1), pigeonite host (Fs52.3Wo10.5; FeO/MnO = 65.2), augite lamella (Fs31.9Wo31.9; FeO/MnO = 60.3), pigeonite clast (Fs60.1Wo7.0, FeO/MnO = 71.1), augite clast (Fs17.2Wo36.9, FeO/MnO = 53.3). Bulk composition: (R. Korotev, WUSL) FeO = 13.7 wt%; Sm = 3.1 ppm, Th = 0.9 ppm, Ir 3.4 ppb. Classification: Achondrite (lunar, mingled basalt-rich breccia). Specimens: A total of 8.4 g of sample and one polished mount are on deposit at UWS. GHupé holds the main mass. |
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