Understanding Roman gold coinage inside out

Journal article

The true purity of Roman silver coinage was hidden by enriching the surfaces of the coins. The question investigated here is whether Roman gold coins were also surfaced enriched. Two non-destructive techniques were employed to do this: X-ray fluorescence (XRF) and a ‘newer’ technique, muonic X-ray emission spectroscopy (μXES). For the latter, the momentum of the muons is controlled, allowing for the composition of the coin to be determined at various depths. Here we show that there is no surface enrichment of the Roman gold coins analysed. Furthermore, we show that XRF and μXES return congruent results at the near surface. This all supports the integrity of surface level analyses of Roman gold coins. We then discuss the broader applicability of our muon technique to the further study of Roman gold coinage, to the cultural heritage sector and to archaeological scientists more generally.

Authors: Green, GA; Ishida, K; Hampshire, BV; Butcher, K; Pollard, AM

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Elsevier
• Journal: Journal of Archaeological Science
• Volume: 134
• Article number: 105470
• Publication date: 2021-08-28
• Acceptance date: 2021-08-13
• DOI: 10.1016/j.jas.2021.105470
• EISSN: 1095-9238
• ISSN: 0305-4403
• Language: English
• Keywords: mu XES; muons; Roman; purity; XRF; gold; non-destructive; FFR