Lunar Meteorite: Tichiya

One of the Tichiya stones. Photo credit: ©2017 Barbra Barrett/MMGM (Maine Mineral and Gem Museum)
Two views of lab sample of Tichiya. Photo credit: Randy Korotev

from The Meteoritical Bulletin, No. 106

Tichiya

(Northwestern Africa)
Purchased: 2016 September
Mass: 9354 g (2 pieces)

Lunar Meteorite (feldspathic breccia)

History: Two similar stones were found about 90 m apart at a location called Tayertand subsequently purchased by DPitt in September 2016 from a dealer in Ouarzazate, Morocco.

Physical characteristics: Two identical dark stones (total weight 9354 g) lacking fusion crust, but with a shiny exterior patina. The fresh interior is very dark and mostly fine grained, but some larger, diffuse beige-colored clasts are visible.

Petrography: (A. Irving and S. Kuehner, UWS) Breccia composed predominantly of mineral clasts of anorthite, olivine, exsolved pigeonite, ilmenite, chromite, Cr-ulvöspinel, silica polymorph, troilite, baddeleyite and kamacite, plus some basalt clasts and glass fragments, in a finer grained matrix.

Geochemistry: Olivine (Fa4.6-56.0, FeO/MnO = 81-93, N = 4), orthopyroxene (Fs39.2Wo1.9, FeO/MnO = 59), pigeonite (Fs23.0Wo9.2, FeO/MnO = 43; Fs41.1Wo15.2, FeO/MnO = 55), subcalcic augite (Fs23.2-32.9Wo33.2-33.9, FeO/MnO = 43-47, N = 2), plagioclase (An94.8-95.9Or0.4-0.6; An58.4Or2.0; N = 3).

Classification: Lunar (feldspathic breccia).

Specimens: 20.4 g including one polished thin section at UWB; remainder with DPitt.

Tichiya is 1 of only 4 lunar meteorites that I know to have a significant (Ce/Ce* <0.8) negative cerium (Ce) anomaly. All are from Northwest Africa (other 3: NWA 11223, NWA 11182, and  NWA 11809). It appears that the light, trivalent elements (La, Sm) are enriched as a result of terrestrial contamination. Curiously, the meteorite does not appear to be weathered more than most NWA lunar meteorites. 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.

Randy Says…

Tichiya (unofficially, Tichiya 001) is not paired with Tichiya 003.

More Information

Meteoritical Bulletin Database

Tichiya

References

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

Lunar Meteorites
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