Ge, Te, and Zn isotopic link between Ryugu and CI chondritesOPEN ACCESS 

E. Wölfer, J. Hellmann, C. Burkhardt, T. Kleine

Geochemical Perspectives Letters, V37, Received 12 May 2025, Accepted 15 August 2025, Published 17 September 2025

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“Analyses of samples returned from asteroid Ryugu have revealed chemical, mineralogical, and isotopic similarities to Ivuna-type (CI) carbonaceous chondrites. Compared to other carbonaceous chondrites, CI chondrites are characterised by heavy isotope enrichments of the moderately volatile elements, but until now no study demonstrated that this is also the case for Ryugu. Here we show that Ryugu and CI chondrites have similar elemental and mass dependent isotope systematics of the moderately volatile elements Ge, Te, and Zn, which are distinct from those of all other carbonaceous chondrites. The mass independent (nucleosynthetic) Zn isotope signatures of Ryugu are also most similar to CI chondrites, although the difference to other carbonaceous chondrites is not well resolved. Our results reinforce the notion that Ryugu and CI chondrites formed from the same precursor materials, and indicate that any processes acting on these materials before or after parent body accretion were similar. Given their similar chemical composition to the Sun, Ryugu/CI chondrites likely record the solar system’s average chemical and mass dependent isotopic composition for moderately volatile elements.”