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Lunar Meteorite

Northwest Africa 2200

Morocco

 


Northwest Africa 2200
(photo credit: David Gregory)

 

lm_nwa2200_2557m.jpg

Lab samples of NWA 2200

(photo credit: Randy Korotev)

 

from The Meteoritical Bulletin, No. 90, Meteoritics & Planetary Science 41, 1383–1418 (2006)

Northwest Africa 2200

Morocco
Find: August 2004
Mass: 552 g

Achondrite: (lunar, feldspathic breccia)

History: A completely crusted, 552 g, ellipsoidal stone was found in the Atlas Mountains, Morocco, and purchased in Erfoud by a Moroccan dealer for D. Gregory in August 2004.

Petrography and Geochemistry: (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 gabbroic 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 (Ni = 10–45 wt%), Ti-rich chromite, Ti-poor chromite, pyroxenelike glass, schreibersite (Ni = 5 wt%), clinopyroxene, ilmenite, troilite, and rare zirconolite. Clinopyroxene and orthopyroxene grains in mineral and lithic clasts have Fe/(Fe+Mg) = 0.258–0.482 with 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.

Classification: Achondrite (lunar, feldspathic breccia). Specimens: A 20.5 g type specimen, one polished thin section, and one polished mount are on deposit at UWS. D. Gregory holds the main mass.

 

Randy Says…

There's a hint of preferred orientation of clasts in the photos. You don't see that often in lunar breccias. Compositionally, it's a typical feldspathic lunar meteorite.

 

More Information

Meteoritical Bulletin Database

NWA 2200

References

Kuehner S. M., Irving A. J., and Gregory D. A. (2005) Lunar feldspathic meteorite NWA 2200; A polymict glassy impact-melt breccia with ferroan anorthosite (FAN) affinities (abstract). 68th Annual Meeting of the Meteoritical Society, number 5137.

Korotev R. L. (2006) New geochemical data for a some poorly characterized lunar meteorites (abstract). In Lunar and Planetary Science XXVII, number 1404, Lunar and Planetary Institute.

Korotev R. L. and Zeigler R. A. (2007) Keeping up with the lunar meteorites (abstract). In Lunar and Planetary Science XXXVIII, abstract no. 1340, Lunar and Planetary Institute.

Korotev R. L., Irving A. J., and Bunch T. E. (2008) Keeping up with the lunar meteorites – 2008 (abstract). In Lunar and Planetary Science XXXIX, abstract no. 1209, 39th Lunar and Planetary Science Conference.

Nagaoka H., Karouji Y., Arai T., Shinotsuka K., Ebihara M., and Hasebe N. (2008) A most ferroan feldspathic lunar meteorite NWA 2200 (abstract). 71st Annual Meeting of the Meteoritical Society, abstract no. 5246, Lunar and Planetary Institute.

Nagaoka H., Karouji Y., Arai T., Ebihara M., and Hasebe N. (2009) Chemical characteristics of the lunar meteorite Northwest Africa 2200 (abstract). Antarctic Meteorites XXXII, Papers Presented to the Thirty-second Symposium on Antarctic Meteorites, p. 45-46. National Institute of Polar research, Tokyo.

Nagaoka H., Karouji Y., Arai T., Ebihara M., Hasebe N. (2013) Geochemistry and mineralogy of a feldspathic lunar meteorite (regolith breccia), Northwest Africa 2200. Polar Science 7, 241-259.

Nishiizumi K. and Caffee M. W. (2006) Constraining the number of lunar and martian meteorite falls (abstract). In Meteorit. Planet. Sci. 41, p. A133, 69th Annual Meeting, Meteoritical Society.

 

 

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Prepared by
: Randy L. Korotev
 
Department of Earth and Planetary Sciences
Washington University in St. Louis

Please don't contact me about the meteorite you think you've found until you read this and this.


e-mail
korotev@wustl.edu

Last revised: 8-Oct-2015