NWA 2200 Lunar Meteorite



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Main Mass

Full slice 11.8 grams



From the Meteoritical Bulletin #90:
  • Northwest Africa 2200
  • Purchased August, 2004
  • Lunar meteorite (feldspathic breccia)

A completely crusted 552 g ellipsoidal stone found in the Atlas Mountains, Morocco was purchased in Erfoud by a Moroccan dealer for D. Gregory (Gregory) in 2004 August.  Classification and mineralogy (S. Kuehner and A. Irving, UWS): Breccia consisting of coarse, greyish to whitish lithic and mineral clasts in a darker glassy to finely crystalline matrix.  Lithic clasts are mainly very fine grained, quench-textured, feldspathic rocks that probably result from impact melting of anorthositic to gabboic anorthositic precursors. A small percentage of the clasts are ophitic-textured mare basalts.  Mineral clasts include anorthitic plagioclase, olivine (Fa30-60), exsolved pigeonite, irregular grains of metal (with ~10-45 wt.% Ni), Ti-rich chromite, Ti-poor chromite, pyroxene-like glass(?) schreibersite (~5 wt.% Ni), clinopyroxene, ilmenite, troilite and rare zirconolite. Clinopyroxene and orthopyroxene grains in mineral and lithic clasts have Fe/(Fe+Mg) = 0.258 to 0.482, and 19 of 23 analyses have Ti/(Ti+Cr) = 0.53-0.75.  FeO/MnO ratios measured for olivine (99.7, 105.5), clinopyroxene (73.7) and orthopyroxene (65.4) are unmistakably within the ranges for these minerals in known lunar rocks.  Feldspar grains in mineral and lithic clasts have a narrow compositional range of An95.8-97.4.   The combination of anorthitic plagioclase and ferroan mafic silicates suggests that the majority of the material in this specimen was derived from FAN-suite lithologies (Kuehner et al., 2005).  Specimens: type specimens, 20.5 g, one polished thin section, and one polished mount, UWS; main mass, Gregory.



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