Northwest Africa 2200
credit: David Gregory)
samples of NWA 2200
credit: Randy Korotev)
Meteoritical Bulletin, No. 90, Meteoritics
& Planetary Science 41,
Find: August 2004
Mass: 552 g
(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.
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.
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
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.
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
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.
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
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
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
H., Karouji Y., Arai T., Ebihara M., Hasebe N.
and mineralogy of a feldspathic lunar meteorite (regolith breccia),
Northwest Africa 2200. Polar
Science 7, 241-259.
K. and Caffee M. W. (2006) Constraining
the number of lunar and martian meteorite falls (abstract). In Meteorit. Planet. Sci.
p. A133, 69th Annual Meeting, Meteoritical Society.
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