Average and core silver content of ancient-debased coins via neutron diffraction and specific gravity

• Published in: Archaeological and anthropological sciences Vol. 10; no. 7; pp. 1585 - 1602
• Main Authors: Debernardi, Pierluigi, Corsi, Jacopo, Angelini, Ivana, Barzagli, Elisa, Grazzi, Francesco, Lo Giudice, Alessandro, Re, Alessandro, Scherillo, Antonella
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.10.2018; Springer Nature B.V
• Subjects: Anthropology; Archaeology; Chemistry/Food Science; Coins; Earth and Environmental Science; Earth Sciences; Geography; Gravity; Life Sciences; Measurement; Neutrons; Original Paper; Specific gravity; Fineness; Silver surface enrichment; Specific gravity; Neutron diffraction; Ancient silver coins
• ISSN: 1866-9557; 1866-9565
• DOI: 10.1007/s12520-017-0464-y

The measurement of the fineness of debased ancient silver coins has proven to be a very difficult issue, which has been studied for a long time. In this paper, this subject is analysed, and the various consequences of the silver surface enrichment (SSE) are discussed exploiting the most recent investigations. A new model is proposed for the complex object that is an ancient-debased silver coin, based on the silver profiles measured on some sectioned specimens. The model is applied to a sample of 43 coins, mainly Roman victoriati, Cisalpine and Illyrian drachms (from late III to I century B.C.). The coins are investigated in two different ways: neutron diffraction (ND) and specific gravity (SG). The results of the two measurements are combined via the proposed model to provide a more complete numismatic information of the original fineness of the monetary alloy. As a result, a relation between SSE thickness and SG is derived, which, for these coinages, allows to estimate the original alloy silver content from a simple SG measurement; the same method can be used to study other debased coinages, provided that all the procedure (ND and SG) is applied.