Electrochemical dating of archaeological gold based on repetitive voltammetry monitoring of silver/copper in depth concentration gradients

The use of repetitive voltammetry for dating archaeological gold objects is described. The method involves the record of the gold- silver-, and copper-related voltammetric responses obtained for metal nanosamples attached to graphite electrodes immersed into HCl electrolytes. This methodology permits to characterize different electrochemical types representative of different manufacturing techniques. Age estimates are based on the assumption that decuprification/desilvering processes advance with time under reasonably uniform conditions. Age calibration curves covering a range of ca. 2500 years were obtained from a set of archaeological samples from the Mapungubwe Gold Collection at the University of Pretoria Museums, South Africa, the Rijksmuseum of Amsterdam, The Netherlands, the Rheinische Landesmuseum Trier of Mannheim (Germany), the Museu de Belles Arts de Castelló, Spain, the Museu de Segovia, Spain, and the repository of the Servei d'Investigació Arqueològica Municipal de València, Spain.