Evaporation-induced copper isotope fractionation: Insights from laser levitation experiments

As a transition metal that is moderately volatile at high temperatures, copper shows limited isotopic fractionation in terrestrial mantle-derived rocks but significant enrichment in its heavier isotope (up to 12.5‰ for 65Cu/63Cu) in objects that experienced volatile loss during formation, such as tektites, trinitite glasses, and lunar rocks. Previous efforts to model the Cu isotope fractionation trend from measurements of δ65Cu in tektites found that the trend cannot be explained by the theoretical isotope fractionation factor (α) for free evaporation of Cu, making it necessary to experimentally study Cu isotope fractionation under conditions similar to tektite formation.