Use of non-traditional heavy stable isotopes in archaeological research

Abstract Recent analytical developments in the field of mass spectrometry have made possible accurate measurements of “non-traditional” isotopic ratios of elements such as Fe, Cu, Ag, Sn, Sb and Hg. The stable isotopes of these elements do not have any radioactive parents, but their ratios undergo limited fractionation from various causes, most of them mass-dependent. These effects can lead to variation in isotopic ratios of natural materials (minerals, rocks, ores, etc.) and in archaeological artifacts derived from them. Research since 2010 has investigated whether variation in these isotopic ratios can be used to infer the geological provenance of archaeological materials, including bronze and glass. Here we review recent research on these isotopic systems in archaeology, their principal applications, as well as expected future developments in their use. We conclude that none of these isotopic systems are likely to be very useful for provenance, mostly because of limited ranges of isotopic ratios and/or extensive overlap between the isotopic ratios of most geological sources. Copper isotope ratios are however a reliable method for inferring the type of ore (supergene versus hypogene) smelted to produce copper, and recent studies indicate that silver isotope ratios can also be applied to this effect.