Lunar Meteorite: Northwest Africa 8641 clan

from The Meteoritical Bulletin, No. 103

Northwest Africa 8641 (NWA 8641)

(Northwest Africa)
Purchased: 2014 May
Mass: 5895 g (1 piece)

Lunar meteorite (feldspathic breccia)

History: Purchased in May 2014 by Darryl Pitt from a dealer in Erfoud, Morocco.

Physical characteristics: A large (5895 g) rounded, ellipsoidal dark gray stone with white clasts visible and with a beige, clayey coating on one side.

Petrography: (A. Irving and S. Kuehner, UWS) Breccia composed of light colored clasts in a darker matrix. Major minerals are olivine, orthopyroxene, pigeonite, augite and anorthite. Minor constituents include symplectitic intergrowths of fayalite+hedenbergite+silica polymorph, ilmenite, Ti-rich chromite, troilite, and rare exsolved pigeonite, kamacite and secondary barite.

Geochemistry: Olivine (Fa_23.3-31.8; FeO/MnO = 94-97, N = 3), orthopyroxene (Fs_29.7Wo_3.1; FeO/MnO = 64), pigeonite (Fs_24.1Wo_6.4; FeO/MnO = 59), augite (Fs_13.6-39.4Wo_39.4-43.5; FeO/MnO = 44-45, N = 2), plagioclase (An_94.6-99.7Or_0.3-0.1, N = 3).

Bulk composition: (R. Korotev, WUSL) INAA of subsamples gave the following mean abundances (in wt.%) FeO 5.35, Na₂O 0.48; (in ppm) Sc 12.3, Ni 140, Ba 320, La 6.4, Sm 2.9, Eu 1.05, Yb 2.0, Lu 0.287, Hf 2.1, Th 0.90.

Classification: Lunar (feldspathic regolithic breccia).

Specimens: 20.5 g including a polished endcut at UWB. The remainder is held by DPitt.

from The Meteoritical Bulletin, No. 103

Northwest Africa 8682 (NWA 8682)

(Northwest Africa)
Purchased: 2014 May
Mass: 82 g (several pieces)

Lunar meteorite (feldspathic breccia)

History: Purchased by Steve Arnold in August 2014 from a dealer in Zagora, Morocco.

Physical characteristics: A batch of identical stones (total weight 82 g), each of which is partly coated by pale tan, clayey soil. Interiors consist of small white to beige clasts in gray matrix.

Petrography: (A. Irving and S. Kuehner, UWS) Breccia composed of a variety of mineral clasts and sparse, small mare basalt clasts in a finer grained, vesicular matrix. Minerals are olivine (including unusually forsteritic grains associated with Cr-pleonaste), orthopyroxene, pigeonite, augite, anorthite, intermediate plagioclase, silica polymorph, fayalite, ilmenite, baddeleyite, troilite, kamacite, merrillite, zirconolite, and minor secondary barite and calcite. One unusual clast consists of K-feldspar + silica polymorph with accessory zirconolite and an unknown Th-Zr-Ti mineral.

Geochemistry: Olivine (Fa_6.8, FeO/MnO = 60; Fa_27.4-50.3, FeO/MnO = 91-103, N = 4), orthopyroxene (Fs_24.5-39.8Wo_4.2-4.1, FeO/MnO = 57-69, N = 2), subcalcic augite (Fs_16.0-34.4Wo_36.4-36.0, FeO/MnO = 45-55, N = 3), fayalite (Fa_93.2, FeO/MnO = 79), anorthite (An_95.1-96.6Or_0.3, N = 2), plagioclase (An_49.1Or_1.1; An_70.7Or_1.8).

Classification: Lunar (feldspathic regolithic breccia).

Specimens: 16.4 g including one polished endcut at UWB. The remaining material is held by Mr. S. Arnold.

from The Meteoritical Bulletin, No. 104

Northwest Africa 10049 (NWA 10049)

(Northwest Africa)
Purchased: 2014
Mass: 56 g (1 piece)

Lunar meteorite (feldspathic breccia)

History: Purchased by Eric Twelker from Habib Naji in Morocco, 2014.

Physical characteristics: Single stone. Saw cut shows white feldspathic clasts and a few dark colored clasts set in a dark gray matrix. There a few, very small, metal grains visible.

Petrography: (C. Agee, UNM) This meteorite is a fine-grained, lunar feldspathic regolith breccia with numerous agglutinates, shock melt zones and impact melt clasts present. Many of the agglutinates and melt veins are heavily vesiculated. There are also many fragmental feldspar grains and some microgabbros present, a few of these fragments are up to several mm in size. Accessory Fe-Ni metal, Fe-sulfide, chromite, and ilmenite are present. Weathering products iron oxide, barite, and calcite were detected.

Geochemistry: (C. Agee and N. Muttik, UNM) Olivine Fa_31.5±4.9, Fe/Mn=99±9, n=29; forsterite Fa_5.8, Fe/Mn=87, n=1; pigeonite Fs_26.6±5.5Wo_6.0±3.8, Fe/Mn=55±4, n=10; augite Fs_22.7±8.2Wo33.1±6.9, Fe/Mn=52±8, n=14; anorthite plagioclase An_94.2±2.6Ab_5.4±2.5Or_0.3±0.2, n=10; labradorite plagioclase An_56.3Ab_37.1Or_6.6, n=1; Shock melt (20 µm defocused electron beam, proxy for bulk meteorite composition): SiO₂=44.5±0.8, TiO₂=0.25±0.08, Al₂O₃=31.3±1.9, Cr₂O₃=0.07±0.01, MgO=3.2±1.8, FeO=3.0±0.4, MnO=0.04±0.02, CaO=17.4±0.4, NiO=0.00±0.00, Na₂O=0.55±0.09, K₂O=0.07±0.01 (all wt%), n=3.

Classification: Lunar feldspathic regolith breccia

Specimens: 12.4 g including a probe mount on deposit at UNM, Twelker holds the main mass.

from The Meteoritical Bulletin, No. 103

Northwest Africa 10077 (NWA 10077)

(Northwest Africa)
Purchased: 2014 July
Mass: 5.27 g (1 piece)

Lunar meteorite (feldspathic breccia)

History: Purchased by Fabien Kuntz in July 2014 from a dealer in Foum El Hisn, Morocco.

Petrography: (A. Irving and S. Kuehner, UWS) Breccia composed of angular mineral fragments in a finer grained matrix containing vesicles. Minerals are anorthite, olivine, orthopyroxene, pigeonite, silica polymorph, bytownite, Cl-bearing apatite, ilmenite, troilite and kamacite.

Geochemistry: Olivine (Fa_23.9-32.0, FeO/MnO = 84-94, N = 3), orthoproxene (Fs_26.6Wo_3.5, FeO/MnO = 68, N = 1), pigeonite (Fs_21.3-23.6Wo_17.4-10.9, FeO/MnO = 53-63, N = 3), plagioclase (An_95.3-96.5Or_0.4; An_83.2Or_0.8; N = 3).

Bulk composition: (R. Korotev, WUSL) INAA of subsamples gave the following mean abundances (in wt.%) FeO 5.2, Na₂O 0.48; (in ppm) Sc 10.2, La 5.9, Sm 2.7, Eu 1.11, Yb 1.83, Lu 0.25, Th 0.9.

Classification: Lunar (feldspathic regolithic breccia). Paired with NWA 8641 based on texture and bulk composition.

Specimens: 1.08 g piece polished on one side at PSF; main mass with Kuntz.

from The Meteoritical Bulletin, No. 104

Northwest Africa 10133 (NWA 10133)

(Northwest Africa)
Purchased: 2014 April
Mass: 54.2 g (many pieces)

Lunar meteorite (feldspathic breccia)

History: Purchased in April 2014 by Sergey Vasiliev and Marc Jost from a dealer in Tan Tan, Morocco.

Physical characteristics: A group of many small beige to gray stones (total 54.2 g).

Petrography: (A. Irving and S. Kuehner, UWS) Following optical examination of all of the small stones constituting the type material, three representative stones were selected for detailed microprobe and bulk chemical analysis. Each specimen consists of small mineral clasts of anorthite, olivine, pigeonite, orthopyroxene, augite, subcalcic augite, forsterite, fayalite, silica polymorph, ilmenite, troilite, zircon (one grain >100 µm) and rare kamacite set within a fine grained vesicular matrix containing minor barite. Rare mare basalt lithic clasts are also present.

Geochemistry: Olivine (Fa_6.0, FeO/MnO = 71; Fa_22.7-29.9, FeO/MnO = 91-106, N = 2; Fa_84.3-89.4, FeO/MnO = 88-99, N = 2), pigeonite (Fs_24.6-31.9Wo_11.4-6.5, FeO/MnO = 56-72, N = 3), orthopyroxene (Fs_26.8-45.0Wo_4.4-3.8, FeO/MnO = 61-73, N = 2), subcalcic augite (Fs_22.0-48.5Wo_25.1-33.0, FeO/MnO = 62-66, N = 3), augite (Fs_13.1-38.5Wo_44.5-39.6, FeO/MnO = 49-60, N = 2), plagioclase (An_93.5-96.5Or_0.4-0.1, N = 4).

Bulk composition: (R. Korotev, WUSL): mean abundances for three separate stones determined by INAA of subsamples are as follows: #A (in wt.%) FeO 5.1, Na₂O 0.49; (in ppm) Sc 10.1, Cr 790, Ni 150, La 5.9, Sm 2.7 Eu 1.07, Yb 1.8, Lu 0.26, Hf 1.9, Th 0.9; #B (in wt.%) FeO 6.1, Na₂O 0.50; (in ppm) Sc 12.0, Cr 930, Ni 290, La 10.0, Sm 4.6, Eu 1.15, Yb 3.2, Lu 0.44 Hf 4.0, Th 1.6; #D (in wt.%) FeO 5.5, Na₂O 0.49; (in ppm) Sc 10.0, Cr 760, Ni 280, La 9.2, Sm 4.3, Eu 1.20, Yb 2.8, Lu 0.39, Hf 3.2, Th 1.4.

Classification: Lunar (feldspathic regolithic breccia). Despite the mineralogical and compositional heterogeneity among these small stones, we conclude that they are paired with Northwest Africa 8641, Northwest Africa 8682 and Northwest Africa 10077.

Specimens: 10.9 g including two polished pieces at UWB. The remaining material is held jointly by Mr. S. Vasiliev and Mr. M. Jost.

Randy Says…

There are geochemical hints that NWA 5000 is a mixture of the large gabbroic clasts that occur in the breccia and a matrix dominated by a material (soil?) compositionally very similar to the NWA 8641 clan.

It is possible that NWA 10783 is a large clast from the NWA 8641 clan.

More Information

Meteoritical Bulletin Database

NWA 8641 | 8682 | 10049 | 10077 | 10133

References

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. Lunar and Planetary Science XLVIII, abstract no. 1498.

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