Separating silver sources of Archaic Athenian coinage by comprehensive compositional analyses

This article demonstrates that distinct and coherent silver sources can be discriminated from surface compositional analyses. In the first large-scale study of Archaic (pre-479 BC) Athenian silver coins in museum collections around the world, we analysed 787 coins by Energy Dispersive X-ray Fluorescence (XRF) spectrometry with a mathematical correction to provide a reliable composition for key diagnostic elements. Principal Component Analysis reveals compositional patterns including at least one copper-lead-gold (Cu, Pb, Au) triplet with strong clustering of data. The pattern for bismuth (Bi) was similar to, but not as clear as
Pb. Considering elemental compositions in combination with a die study and isotopic analyses in the literature, we reveal when Lavrion was the metal source from which Wappenmünzen and Owl coinage types were struck, providing important new understanding about Athenian history in the pivotal period of transition from tyranny to democracy in the late sixth century BC. Beyond this specific example, we contend that XRF spectrometry could have wider application in studies of ancient silver, not least for a simplified triage protocol to help determine which silver artefacts should be subjected to slower, more costly and invasive trace elemental and isotopic analyses.