Lunar Meteorite: Northwest Africa 2998 & 7262 (paired stones?)

Morocco

 

Northwest Africa 2998 (163 g) is an oriented stone with a nearly complete fusion crust. Photo credit: anonymous finder

Two views of Northwest Africa 7262 (413), which also has a nearly complete fusion crust. Photo credit: A. Aaronson

Thin section of NWA 7262. Field of view: 2.5 cm wide. Note the vesicular fusion crust on the lower left.  Photo credit: Randy Korotev

Lab samples of NWA 2998. Photo credit: Randy Korotev

from The Meteoritical Bulletin, No. 91

Northwest Africa 2998 (NWA 2998)

Algeria*
Find: 2006
Mass: 163 g (1 piece)

Achondrite (lunar, anorthositic breccia)

History: Found in the southern Algerian desert in May 2006. Purchased by A. Aaronson in Morocco, June 2006.

Physical characteristics: Medium brown, oriented, nearly complete 163 g stone. The fusion crust is fresh, with very prominent flow lines.

Petrography: (T. Bunch and J. Wittke, NAU) Breccia-in-breccia structure; breccia clasts are granulated or cataclastized with fine-grained to melt matrix. Vesiculated shock-melt veins and isolated glass clumps are common. Consists of partially maskelynitized plagioclase fragments (47 vol%), shock-melt anorthositic clasts (38 vol%), dark glasses (7 vol%), norites and troctolites (6 vol%), and olivine and pyroxene fragments (2 vol%). No mare components were observed.

Mineral compositions and geochemistry: Plagioclase (An93.6–99; FeO = 0.15–0.35 wt%), olivine (Fa21.7–34.6; FeO/ MnO = 79–87), orthopyroxene (Fs22.5–29.5Wo2.1–3.2; FeO/MnO = 53–59), pigeonite (Fs49.3Wo5.2; FeO/MnO = 53), augite exsolution lamellae in pigeonite (Fs27.4Wo43.1), ferroaugite (Fs45.8Wo38.9; FeO/MnO = 28). Bulk composition: (R. Korotev, WUSL, INAA of 224 mg sample) FeO = 2.7 wt%; Ni =60, Sm = 0.42, and Th = 0.13 (all ppm).

Classification: Achondrite (lunar, anorthositic breccia).

Type specimen:
 A total of 20.4 g and one thin section are on deposit at NAU. The main mass holder is anonymous.

*The purchaser says that it is from Morocco [RLK].

from The Meteoritical Bulletin, No. 101

Northwest Africa 7262  (NWA 7262)

(Northwest Africa)
Purchased: 2012 Feb
Mass: 413 g (1 piece)

Classification: Lunar meteorite (feldspathic breccia)

History: Purchased by Adam Aaronson in Temara, Morocco, in 2012 February.

Physical characteristics: A single stone (413 g) broken naturally into five pieces that fit together. Abundant white clasts visible through the pale, translucent fusion crust.

Petrography: (A. Irving and S. Kuehner, UWS; A. Greshake, MNB). Felsic fragmental breccia composed of feldspar-rich clasts in a very fine grained matrix. Minerals are olivine, orthopyroxene, pigeonite, subcalcic augite, anorthite, silica, fayalite, Ti-chromite, troilite and minor kamacite (as irregular scraps).

Geochemistry: Olivine (Fa6.8-52.6, FeO/MnO = 72-127), orthopyroxene (Fs28.6-45.6Wo3.8-4.2, FeO/MnO = 53-64), subcalcic augite (Fs25.4Wo34.3, FeO/MnO = 50), augite (Fs17.1Wo41.6, FeO/MnO = 65), plagioclase (An93.3-96.3Or0.1). Bulk composition (R. Korotev, WUSL): mean values from INAA of subsamples are 3.1 wt.% FeO, 5.7 ppm Sc, 70 ppm Ni, 1.3 ppm La, 0.58 ppm Sm, 0.77 ppm Eu, 0.47 ppm Yb, 0.22 ppm Th.

Classification: Lunar (feldspathic breccia). This specimen is very similar in appearance, mineralogy and bulk composition to NWA 2998, and it is likely that these are paired.

Specimens: A total of 20.3 g of material and one polished thin section are on deposit at UWB. The remaining material is held by Aaronson.

Randy Says…

Northwest Africa NWA 2998 and 7262 may not be terrestrially paired as the owner of both stones believes that they were found in different places. But my analyses of subsamples of the two stones overlap for all elements measured, and the stones look rather similar to each other.  It’s one of the most feldspathic of lunar meteorites.

More Information

Meteoritical Bulletin Database

NWA 2998 | 7262

References

Joy K. H., Burgess R., Ruzie L, and Clay P. L. (2014) Composition, age and regolith history of feldspathic lunar meteorites. 77th Annual Meeting of the Meteoritical Society, abstract no. 5345.

Korotev R. L. and Irving A. J. (2013) Keeping up with the lunar meteorites  201344th Lunar and Planetary Science Conference, abstract no. 1216.

Korotev R. L. and Irving A. J. (2021) Lunar meteorites from northern Africa. Meteoritics & Planetary Science, 206–240. 

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

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

Korotev R. L., Jolliff B. L., and Zeigler R. A. (2010) On the origin of the moon’s feldspathic highlands, pure anorthosite, and the feldspathic lunar meteorites41st Lunar and Planetary Science Conference, abstract no. 1440.

Lunar Meteorites | List of Lunar meteorites