Lunar Meteorite: Northwest Africa 11223 & 11809 (paired stones)

northwestern Africa

Two slices of Northwest Africa 11223 showing the same clasts. Photo credit: Ian Nicklin

Two views of Northwest Africa 11809. Photo credit: Fabien Kuntz

Lab sample of NWA 11223. Thanks to Ian Nicklin for the sample. Photo credit: Randy Korotev

Lab sample of Northwest Africa 11809. Photo credit: Randy Korotev

from The Meteoritical Bulletin, No. 106

Northwest Africa 11223 (NWA 11223)

(Northwestern Africa)
Purchased: 2017
Mass: 28 g (1 piece)

Lunar Meteorite (feldspathic breccia)

Physical characteristics: The ROM specimen is one of many pieces found by a meteorite hunter in Morocco. The largest fragments are over 2 kg, with many smaller pieces adding to a total of approximately 10 kg. All specimens observed lacked fusion crust and most were covered in a very thin surface coating of white caliche. However two specimens, which were apparently exposed to the desert winds, showed no caliche, exposing a dark-gray interior with obvious lithic clasts.

Petrography: (ROM; K. Hewson, V. Di Cecco, I Nicklin, ROM) In hand sample and thin section the specimen shows lithic and mineral clasts set in a dark-gray, glassy matrix. No vesicles were observed. The largest lithic clast in the ROM specimen is light gray in color and measures 1 × 0.5 cm. Two other relatively large clasts are of a more mixed mineralogy.

Geochemistry: (K. Hewson, V. Di Cecco) Feldspar grains have highly anorthitic composition (An90.9-98.6Ab0.0-7.4Or0.1-2.1, n = 94), which is consistent both in the clasts and the matrix. Olivine grains, although rare, are forseritic (Fa28.0-44.5, FeO/MnO = 84.8-119.2, n=15). Pyroxene grains are more common than olivine and are variable in composition. They include augite (En30.2-48.4Fs23.7-26.6Wo2.5-26.6, FeO/MnO = 52.4-61.1, n=5), pigeonite (En40.4-68.0Fs23.3-49.0Wo6.0-19.1, FeO/MnO = 51.8-63.6, n=14) and enstatite (En64.0-65.5Fs31.6-32.1Wo2.5-3.9, FeO/MnO = 57.6-62.9 n=3).

Classification: Lunar (feldspathic impact-melt breccia). The largest lithic clast noted has an anorthitic composition, as given by the geochemistry. The two other relatively large clasts have noritic and olivine-noritic compositions based on geochemistry and mineral modality. Mineral fragments are anorthite, clino and orthopyroxenes and rare olivine. Both the lithic and mineral clasts show extensive shock features including mosaicism, planar fracturing and, in the lithic clasts, granularization of the component minerals. Despite the generally uniform caliche coating on most of the specimens the weathering is minimal being confined largely to the exterior but with some very few, very fine fractures containing material similar to the caliche coating which is predominantly barite.

Specimens: The ROM holds the main mass of this sample, which originally weighed 28 g. It is now composed of 2 pieces weighing 17.52 and 4.83 g, a thin section, a thin section billet, and 0.20 g of cutting dust.

from The Meteoritical Bulletin, No. 107

Northwest Africa 11809 (NWA 11809)

Northwestern Africa
Purchased: September 2017
Mass: 80 g (1 piece)

Lunar meteorite (feldspathic breccia)

History: Purchased by Fabien Kuntz in September 2017 from a dealer in Erfoud, Morocco.

Petrography: (A. Irving and S. Kuehner, UWS) Breccia composed of angular mineral clasts of anorthite, olivine, orthopyroxene, pigeonite, subcalcic augite and Ti-chromite in a finer grained matrix containing minor barite.

Geochemistry: Olivine (Fa30.0-41.3, FeO/MnO = 87-97, N = 3), orthopyroxene (Fs35.7Wo4.2, FeO/MnO = 56), pigeonite (Fs25.2-29.8Wo7.9-10.1, FeO/MnO = 52-63, N = 2), subcalcic augite (Fs15.8Wo30.1, FeO/MnO = 56), anorthite (An92.0-95.0Or0.2-0.1, N = 2).

Classification: Lunar (feldspathic breccia).

Specimens: 14.11 g including a polished slice at UWB; main mass with Kuntz.

Randy Says…

Rare earth element (REE) concentrations in 5 subsamples of NWA 11223 and 3 subsamples of NWA 11809, a feldspathic impact-melt breccia. This is 1 of only 5 lunar meteorites that I know to have a significant (Ce/Ce* <0.8) negative cerium (Ce) anomaly. All are from Northwest Africa (other 4: NWA 10318, NWA 10495, NWA 11182, and Tichiya).  Curiously, the meteorite does not appear to be weathered more than most NWA lunar meteorites. Perhaps related, the Eu concentration is unusually high (Eu/Sm is 1.6x and Eu/Na is 1.2x greater than other meteorites of similar composition). In the figure, Pr and Nd values calculated by interpolation between La and Sm. Dy, Ho, Er, and Tm values interpolated between Tb and Yb. The Gd value is the mean of the La-Sm extrapolation, the Sm-Tb interpolation, and the Yb-Tb extrapolation.

More Information

Meteoritical Bulletin Database

NWA 11223 | 11809

References

Hewson K., Tait K. T., Di Cecco V, and. Nicklin I. (2017) The classification of lunar meteorite Northwest Africa 11223. 80th Annual Meeting of the Meteoritical Society, abstract no. 6328.

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

Qin L., Day J. M. D., and Tait K.T. (2020) Oxidative impact processes revealed in Northwest Africa 11223.  51st Lunar and Planetary Science Conference, abstract no. 2318.

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