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Lunar Meteorite

Northwest Africa 7611, 8277, 10480, & 10566
(assumed paired stones)

Morocco, northwestern Africa

 

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Northwest Africa 7611
(photo credit: Mike Hankey)

 

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Two images of Northwest Africa 8277
(photo credit: Adam Aaronson)

 

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Sawn face of Northwest Africa 7611
(photo credit: Matt Morgan)

 

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Sawn faces of NWA 8277. Click on image for enlargement.
(photo credit: Gary Fujihara)

 

 

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Lab samples of NWA 7611. Click on image for enlargement. Thanks to Carl Agee for the sample.
(photo credit: Randy Korotev)

 

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Lab samples of NWA 8277. Click on image for enlargement. Thanks to Carl Agee for the sample.
(photo credit: Randy Korotev)

 

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Northwest Africa 10480
(photo credit: Philippe Schmitt-Kopplin)

 

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Lab sample of NWA 10480. Thanks to Philippe Schmitt-Kopplin for the sample.
(photo credit: Randy Korotev)

         

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Lab sample of Northwest Africa 10566. Thanks to Ian Nicklin for the sample.
(photo credit: Randy Korotev)

         

from The Meteoritical Bulletin, no. 101

Northwest Africa 7611

Morocco
Found: 2012 May
Mass: 916 g

Lunar meteorite

History: Reportedly found near the Moroccan/Algerian border in May 2012. Purchased from a Moroccan meteorite dealer in 2012.

Physical characteristics: Single 916 g stone, no fusion crust, smooth exterior with numerous light- and dark-colored clasts, saw cuts reveal brecciated texture with white feldspar and green-brown pyroxene and olivine grains (up to 3 mm) set in a darker gray-green matrix; scattered gabbroic and dark clasts up to 1 cm.

Petrography: (C. Agee, UNM; A. Irving, UWS) Microprobe examination of a polished 7 × 2 cm sawn slice and a separate polished mount shows a fragmental breccia of plagioclase, pyroxene, and olivine grains in a wide range of grain sizes. A prominent ~1-cm pyroxene-plagioclase gabbroic clast was observed as well as several smaller gabbroic fragments. One small clast consists of intergrown hedenbergite+fayalite+silica (after pyroxferroite). The groundmass is variable with some domains showing a uniform fine-grained subophitic plagioclase-pyroxene texture, while other domains show densely packed mineral clasts ranging from 10-300 µm. There are several sharp boundaries between the various textural domains, with at least two compositionally distinct olivine populations, and a wide range of pyroxene compositions, indicating multiple lithologies of a mingled fragmental breccia. Accessory ilmenite, silica polymorph, minor zircon, troilite, Ti-bearing chromite, Ni-free iron metal and kamacite are present.

Geochemistry: (C. Agee and M. Spilde, UNM; A. Irving and S. Kuehner, UWS). Fayalitic olivine Fa90.6±5.7, Fe/Mn=90±4, n=15; forsteritic olivine Fa31.6±11.1, Fe/Mn=93±9, n=3; pyroxene Fs43.6±13.3Wo20.2±8.5, Fe/Mn=67±8, n=37; pyroxene in gabbroic clast Fs45.3±13.1 Wo15.4±5.3, Fe/Mn=69±7, n=12; plagioclase An93.5±1.5Ab6.0±1.4Or0.5±0.5, n=13. Bulk composition (R. Korotev, WUSL). INAA on 4 subsamples gave the following mean values: Na2O=0.405, CaO=14.8, FeO=11.27 (wt%); Sc=25.1, Cr=1692, Co=37.6, Ni=181, La=6.38, Nd=8.9, Sm=3.07, Eu=0.891, Lu=0.321, Hf=2.12, Ir=0.0044, Au=0.0036, Th=0.97, U=0.36 (ppm). Oxygen Isotopes, laser fluorination (K. Ziegler, UNM), 6 analyses on 3 acid-washed aliquots gave mean values d17O=3.161±0.080, d18O=5.931±0.031, Δ17O=0.030±0.075 (linearized, all permil).

Classification: Achondrite (lunar, mingled breccia), high bulk FeO and Sc, and fayalitic olivines suggest the presence of a mare basalt component.

Specimens: A total of 20 g is on deposit at UNM. The remainder is divided between Jay Piatek, Matt Morgan, Mike Hankey, and Haag; Jay Piatek holds the main mass.

 

from The Meteoritical Bulletin, No. 103

Northwest Africa 8277

(Northwest Africa)
Purchased: 2013
Mass: 773 g

Classification: Lunar meteorite (feldspathic breccia)

History: Purchased by Adam Aaronson in Morocco, 2013.

Physical characteristics: Single stone, no fusion crust, irregular sandblasted exterior with numerous light- and dark-colored clasts. Saw cut reveals brecciated texture with white feldspar and green-brown pyroxene and olivine grains (up to 3 mm) set in a dark gray-green matrix.

Petrography: (C. Agee, UNM) Microprobe examination of polished mount shows a fragmental breccia of plagioclase, pyroxene, and olivine grains in a wide range of grain sizes. The groundmass is variable with some domains showing a uniform fine-grained subophitic plagioclase-pyroxene texture, while other domains show densely packed mineral clasts ranging from 10-300 µm. There are several sharp boundaries between the various textural domains, with at least two compositionally distinct olivine populations, and a wide range of pyroxene compositions, indicating multiple lithologies of a mingled fragmental breccia. Accessory ilmenite, silica polymorph, and troilite.

Geochemistry: (C. Agee, UNM). Fayalitic olivine grain Fa92.0, Fe/Mn=92; forsteritic olivine Fa41.1±11.8, Fe/Mn=103±8, n=9; pyroxene Fs40.5±12.9Wo22.4±9.4, Fe/Mn=65±9, n=63; plagioclase An90.9±7.2Ab8.6±6.8Or0.5±0.5, n=30.

Classification: Achondrite (lunar breccia), comparison of macroscopic and backscatter-electron textures, geochemistry of pyroxenes, olivines, and plagioclase, indicate that this meteorite is likely paired with NWA 7611.

Specimens: A total of 21 g including a probe mount on deposit at UNM. Aaronson holds the main mass.

 

from The Meteoritical Bulletin, No. 104

Northwest Africa 10480

(Northwest Africa)
Purchased: 2015
Mass: 33 g

Classification: Lunar meteorite

History: The meteorite was purchased from the Moroccan meteorite dealer Ismaili at the mineral fair in Munich, Germany.

Physical characteristics: One small individual covered with a black shiny crust was recovered from the north-African Sahara.

Petrography: The meteorite is a polymict breccia composed of lithic and mineral clasts set in a fine-grained clastic matrix. Lithic clasts are dominantly gabbroic, basaltic and impact melt up to 5 mm in size; mineral clasts include olivine, fayalite, pyroxene with very fine exsolution lamellae, and feldspar grains. Accessories are pigeonite (Fs55.3Wo13.7), Ti-chromite, ilmenite, and silica. Some melt veins and pockets are present.

Geochemistry: olivine: Fa34.1±2.2 (Fa31.7-40.3, n=24) FeO/MnO mean= 100±9; fayalite: Fa92.3±3.9 (Fa83.7-97, n=26) FeO/MnO mean= 97±5; Ca-pyroxene: Fs39.1±9.5Wo32.4±9.6 (Fs29.7-55.8Wo20.3-43.3, n=33, FeO/MnO mean= 79±11.9); calcic plagioclase: An93.4±1.6 (An90.2-94.6, n=16).

 

from The Meteoritical Bulletin, No. 104

Northwest Africa 10566

(Northwest Africa)
Purchased: 2015 January
Mass: 130 g

Classification: Lunar meteorite (feldspathic breccia)

History: Purchased by Dr. David Gregory in January 2015 from a Moroccan dealer at the Tucson Gem and Mineral Show.

Petrography: (A. Irving and S. Kuehner, UWS) Fragmental breccia composed of angular mineral clasts of anorthite, pigeonite, ferropigeonite, orthopyroxene, augite, fayalitic olivine, silica polymorph, ilmenite, Cr-Ti-Fe spinel, troilite and kamacite, plus sparse rounded to angular glass fragments, set in a finer matrix. Some pigeonite grains are exsolved.

Geochemistry: Low-Ca pyroxene (Fs29.8Wo5.2, FeO/MnO = 50), pigeonite (Fs23.7Wo10.0, FeO/MnO = 44), ferropigeonite (Fs55.2Wo16.2, FeO/MnO = 66), augite (Fs44.5Wo38.9, FeO/MnO = 66), fayalite (Fa71.2; Fa96.2; FeO/MnO = 82-108; N = 2), plagioclase (An94.6-97.0Or0.2-0.0, N = 2). Bulk composition (R. Korotev, WUSL): INAA of subsamples gave (in wt.%) Na2O 0.41, FeO 13.86; (in ppm) Sc 30.2, Cr 1920, Co 42.3, Ni 190, La 6.76, Sm 3.20, Eu 0.888, Yb 2.30, Lu 0.324, Hf 2.2, Th 0.93.

Classification: Lunar (feldspathic breccia). Paired with NWA 7611 and NWA 8277 based on matching bulk elemental compositions.

Specimens: 20 g including one polished thin section at ROM; remainder with Gregory.

 

 

Randy Says…

Northwest Africa 7611 (symbol 7 in the figure below), NWA 8277 (8), 10480 (0) and 10566 (5) are regolith breccias that are almost certainly paired with each other and that each consist of a mixture of feldspathic and basaltic rock pieces. Compositionally, they are indistinguishable from NWA 4884 (4) and together the four stones are different from any other NWA lunar meteorites. A colleague who has seen both NWA 4884 and NWA 7611 in hand says that they look different. The one compositional difference is that NWA 7611, NWA 8277, and NWA 10566 are all considerably more contaminated with terrestrial barium (Ba) than is NWA 4884, and this is a good argument that they were not found in the same location. So, that leaves the coincidence that NWA 4884 and NWA 7611/8277/10566 are launch pairs that both landed in the Sahara. But, maybe it’s not as much of a coincidence as it first seems. These four NWA stones are also compositionally indistinguishable to QUE 94281 (Q), Yamato 793274/981031 (Y), and DEW 12007 (D), all from three different places in Antarctica!

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In the figure, numeric points each represent a small (25-35 mg) subsample of the five NWA stones. For “well-behaved” elements like iron and sodium (left) the points lie along a trend between the feldspathic and basaltic components of the meteorites. NWA 8277 (8) has higher FeO on average than does NWA 7611 (7) because my small sample of NWA 8277 is a bit richer mare basalt than are my samples of the other two stones. NWA 4884 (4) lies in-between. Barium concentrations (right) in NWA 4884 are the same as for the Antarctic meteorites (D, Q, and Y). NWA 7611, 8277, and 10291 are contaminated with Ba from terrestrial alteration in the hot, but sometimes wet desert.

 

More Information

Meteoritical Bulletin Database

NWA 7611 | 8277 | 10480 | 10566

References

Agee C. B., Korotev R. L., and Irving A. J. (2013) Petrology and bulk composition of two lunar fragmental breccias: Northwest Africa 7493 and Northwest Africa 7611. In 44th Lunar and Planetary Science Conference, abstract no. 2629.

Korotev R. L. (2013) Siderophile elements in brecciated lunar meteorites. In 44th Lunar and Planetary Science Conference, abstract no. 1028.Korotev R. L and Irving A. J. (2013) Keeping up with the lunar meteorites - 2013. In 44th Lunar and Planetary Science Conference, abstract no. 1216.

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. and Irving A. J. (2016) Not quite keeping up with the lunar meteorites – 2016. 47th Lunar and Planetary Science Conference, abstract no. 1358.

Korotev R. L. and Irving A. J. (2017) Still not keeping up with the lunar meteorites – 2017. 48th Lunar and Planetary Science Conference, abstract no. 1498.

Korotev R. L., Jolliff B. L., Zeigler R. A., and Haskin L. A. (2003) Compositional constraints on the launch pairing of three brecciated lunar meteorites of basaltic composition, Antarctic Meteorite Research 16, 152-175.

Nishiizumi K., Caffee M. W., and  Jull A. J. T. (2016) Exposure history of Mount DeWitt 12007 and proposed launch-paired Northwest Africa 4884, 7611, and 8277 lunar meteorites. 79th Annual Meeting of the Meteoritical Society, abstract no. 6514.

 

 

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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: 5-February-2017