Nanoscale distribution of Ge in Cu-rich sphalerite

Denis Fougerouse (1) , Alexandre Cugerone (2) , Steven M Reddy (1) , Kai Luo (3) , Vincent Motto-Ros (4)

1 Curtin University
2 Department of Earth Sciences [Geneva]
3 Yunnan University
4 iLM - SPECTROBIO - iLM - Spectrométrie des biomolécules et agrégats

A large proportion of the critical elements resources Ge, Ga, and In are associated with sphalerite in Pb-Zn ore deposits. Germanium in sphalerite has been proposed to be structurally bound in the crystal lattice. Using a combination of microstructural, geochemical and nanoscale observations, we show that Ge can be hosted in sphalerite crystal structure as well as nanoparticles of briartite (Cu 2 (Zn,Fe)GeS 4). The structurally-bound Ge was preserved in undeformed sphalerite grains from the Saint-Salvy Pb-Zn vein deposit (France), whereas the briartite nanoparticles were observed in metamorphosed sphalerite from Arre. The briartite nanoparticles likely exsolved from sphalerite during the Pyrenean-Alpine metamorphism and deformation. The presence of nanoparticles may harden the sphalerite during crystalplastic deformation and help to preserve the critical elements resources of Pb-Zn deposits during metamorphism.

Mots clés: Critical minerals; By-products; Exsolution; Solid-solution

Domaines: Géochimie

Denis Fougerouse, Alexandre Cugerone, Steven M Reddy, Kai Luo, Vincent Motto-Ros. Nanoscale distribution of Ge in Cu-rich sphalerite. Geochimica et Cosmochimica Acta, 2023, 346, pp.223-230. ⟨10.1016/j.gca.2023.02.011⟩. ⟨hal-04381619⟩