Multi-analytical approach for an archaeometric study on orichalcum coins

Abstract

Orichalcum is a Cu-Zn based alloy known since the 1 st millennium BC. The cementation was the ancient technique used for its production. The PhD project here presented aimed to characterise this alloy and to evaluate its degradation: for this purpose, non-destructive, nano-invasive and destructive techniques were used on a collection of ancient coins issued from the 1 st century BC to the end of the 1 st century AD. In particular, a multi-analytical approach was used: to investigate the patinas and their corrosive patterns, to study the alloy microstructures and their degradation, to describe the dezincification process and grouping the coins by emission. In addition, quantitative analyses allowed a complete characterization of this ancient alloy. The multi-analytical approach allowed to review the previous theories used for dating samples in orichalcum. This project wanted to contribute to the current knowledge on Roman coinage and to attempt to investigate the mechanisms of corrosive processes affecting ancient alloys.