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Lunar Meteorite

Northwest Africa 8632

northwestern Africa

 

Northwest Africa 8632
(photo credit: Luc Labenne)

 

NWA 8632 in the lab
(photo credit: Randy Korotev)

 

from The Meteoritical Bulletin, No. 103

Northwest Africa 8632

Morocco
Purchased: 2014 June
Mass: 23.8 g

Classification: Lunar meteorite (basalt)

History: Purportedly found near Chwichiya in 2013 and purchased by Luc Labenne in June 2014 from a dealer in Ouarzazate, Morocco.

Physical characteristics: A single, small, dense black stone (23.8 g) with a flat, squarish shape and no fusion crust. Magnetic susceptibility log ? = 3.08 (X in nm3/kg) (J. Gattacceca, CEREGE).

Petrography: (A. Irving and S. Kuehner, UWS) Porphyritic texture. Subhedral zoned olivine phenocrysts (up to 2.3 mm long, yellowish in thin section) are set in a groundmass composed mainly of elongate, zoned clinopyroxene grains (clear with pink rims), smaller olivine grains and interstitial regions (opaque in thin section) consisting of ilmenite needles, Ti-chromite, fine clinopyroxene, fayalite and glass. No plagioclase was found. Small patches and veinlets of pale yellow devitrified glass are present.

Geochemistry: Olivine phenocrysts (cores Fa32.5-32.8, FeO/MnO = 90-100, N = 3; rim Fa48.8, FeO/MnO = 98), groundmass olivine (Fa72.6-74.1, FeO/MnO = 91-97, N = 3), augite (Fs23.7-27.1Wo40.1-40.5, FeO/MnO = 53-55, TiO2 = 2.4-2.6 wt.%, Al2O3 = 5.9- 6.1 wt.%, N = 2), subcalcic augite (Fs26.6-27.0Wo30.8-36.1, FeO/MnO = 54-60, TiO2 = 1.9-2.1 wt.%, Al2O3 = 4.7-5.6 wt.%, N = 2), ferroan subcalcic augite rim (Fs41.9Wo34.1, FeO/MnO = 63, TiO2 = 3.2 wt.%, Al2O3 = 8.1 wt.%). Bulk composition (R. Korotev, WUSL) INAA of subsamples gave the following mean abundances (in wt.%) FeO 22.6, Na2O 0.28; (in ppm) Sc 51.1, Ni 70, La 7.8, Sm 4.7, Eu 0.89, Yb 4.1, Lu 0.58, Hf 3.4, Th 1.25.

Classification: Lunar (mare basalt).

Specimens: 4.6 g including one polished thin section, one polished thick section and one polished mount at UWB. The main mass is held by Labenne.

 

Randy Says…

Northwest Africa 8632 is the tenth unbrecciated mare basalt among the lunar meteorites. It’s a low-Ti basalt (2.5% TiO2) that is compositionally distinct from the other basaltic lunar meteorites.

 

More Information

Meteoritical Bulletin Database

NWA 8632

References

 

Cato M. J., Fagan A. L. Gross J. (2016) Crystal size distribution of low-Ti lunar basalt-Northwest Africa 8632. 47th Lunar and Planetary Science Conference, abstract no. 2751.

Fagan A. L., Gross J., Ramsey S., and Turrin B. (2018) Northwest Africa 8632- Recording young lunar volcanism. 49th Lunar and Planetary Science Conference, abstract no. 2584.

Fagan A. L., Udry A., Gannon J. P., Cato M. J., and the Spring 2017 WCU Petrology (GEOL 355) class1 (2018) Northwest Africa 8632 – Crystal size distribution variation & potential link to Northwest Africa 032. 49th Lunar and Planetary Science Conference, abstract no. 2601.

 

Korotev R. L. and Irving A. J. (2015) Keeping up with the lunar meteorites 2015. 46th Lunar and Planetary Science Conference, abstract no. 1942.

 

Korotev R. L., Irving A. J., Wittmann A., Kuehner S. M., Chennaoui-Aoudjehane H., and Labenne L. (2015) Petrology and composition of lunar mare basalt meteorite Northwest Africa 8632 from Chwichiya, Morocco. 46th Lunar and Planetary Science Conference, abstract no. 1195.

Schiller M., Bizzarro M., and Fernandes V. A. (2018) Isotopic evolution of the protoplanetary disk and the building blocks of Earth and the Moon. Nature 555, 507-510.

Tang C. P, Sawchuk K, and Warren P. H. (2018) A textural/mineralogical gradient within vitrophyric mare basalt Northwest Africa (NWA) 8632. 49th Lunar and Planetary Science Conference, abstract no. 2029.

 

 

 

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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 that
you’ve found until you read this and this.

 

e-mailkorotev@wustl.edu

Last revised: 27 November 2018