Roman lead ingots from Macedonia—the Augustan shipwreck of Comacchio (prov. Ferrara, Italy) and the reinterpretation of its lead ingots’ provenance deduced from lead isotope analysis

Abstract

A shipwreck of the 3rd/2nd decade BC found near Comacchio (prov. Ferrara, Italy) in 1980 contained not only well-preserved technical equipment and commercial goods but also 102 Roman lead ingots. Since then, the origin of the ingots has been intensively discussed. Domergue et al. (2012) connected the epigraphic elements with lead isotope analyses and favored the southeastern Spanish lead ore mines being the source of the lead metal. An origin from the Balkan region (Illyricum) was favored by Dušanić (2008). Due to our investigations, both assumptions cannot be maintained. We present a new interpretation of the lead’s isotope signature which best match data of ore deposits from Chalkidiki, Thasos island, and Pangaion mountains in the northern Aegean region.

Mints not Mines: a macroscale investigation of Roman silver coinage

“…This could implicate Chalkadiki in Northern Greece, which has ores with lead isotope signatures (Frei 1992) that are consistent with these coins. The lead ingots from the Augustan shipwreck of Comacchio, recently attributed to the ores of the northern Aegean region (Bode et al 2021), would support this ore provenance. The main problem with pursuing this line of enquiry is that there is little archaeological evidence to suggest Roman exploitation in this region (Hirt 2020, 111-24), and the LIA signatures of the majority of coins in the dataset, as with the Pompeii lead pipes (Boni et al 2000), can be generated by mixing almost any Hercynian and Alpine source in various proportions.…”

“…Figure 18 presents the same data as Figure 17 for coins with low-bismuth lead (log(Bi/Pb) <-5) values (note: coins minted in the West are not plotted here because none of these coins had values of log(Bi/Pb) <-5). Two prospective low-bismuth lead supplies, from Britain (Ponting 2018) and from the Augustan shipwreck of Comacchio (Ferrara, Italy) (Bode et al 2021), have also been plotted. Although the lead used at Pompeii and from the ingots recovered in Germania is consistent with the low-bismuth lead used to refine some of the coins minted in the East and at Rome, lead from Britain (from Mendip lead) is not.…”

“…Although not a perfect match, lead ingots with low concentrations of bismuth, that is log(Bi/Pb) <-5, from the Augustan shipwreck of Comacchio, recently re-evaluated by Bode et al (2021) to have derived from Macedonia (i.e. the ore deposits of Chalkidiki, Thasos island, and Mt Pangaion in the northern Aegean region), lie close to the coins (Figure 17) and may provide a geological provenance for this geologically young source.…”

“…The ore source for these ingots was initially attributed to south-east Iberia based on lead isotope analyses and epigraphic elements (Domergue et al 2012). However, the mismatch between the LIA signatures of the Cartagena lead ingots with Imperial coinage in Figure 8, together with higher levels of bismuth associated with lead found in coins minted in the West than the concentrations of bismuth found in the Comacchio ingots, would suggest that the Macedonian provenance advocated by Bode et al (2021) is much more probable. (Bode 2008;Bode et al 2009).…”