Retracing Magna Graecia's silver: coupling lead isotopes with a multi‐standard trace element procedure

Abstract

This study presents the results of compositional and lead isotopic analysis of coinage issued by the Greek colonies of Syracuse, Metapontum, Taras and Thurium in the fifth to third centuries bce. The data suggest that each colony in Magna Graecia, regardless of its motherland roots and despite ongoing conflicts between the cities, had access to the same silver, and that this supply was stable overall throughout their period of minting and issuing coinage. The paper retraces the silver sources of the colonies and points out a potential supply route for the metal. It includes a method development for a multi‐standard quantification approach for laser ablation‐inductively coupled‐mass spectrometry (LA‐ICP‐MS) analysis of silver.

ROME'S Rise to Power. Geochemical Analysis of Silver Coinage from the Western Mediterranean (Fourth to Second Centuries BCE)

“…Even though both reference data clusters comprise coins from the 3 rd and the 2 nd century BCE, the Variscan‐trending cluster predominantly consists of coins from the 2 nd century BCE. Similar Pb isotope compositions as for Group I (Figure b) have been determined for coins issued by the Greek cities of Magna Graecia (Birch et al in press; Birch et al ). Their isotope signatures in turn are consistent with those of coinage from the Greek mainland (Desaulty et al .…”

“…Drilling chips from the first few millimetres were discarded to avoid surficial material potentially affected by e.g. corrosion processes or conservation treatment (also see Birch et al () and Birch et al (in press)) [Correction added on 10 March 2020, after first online publication: “micrometres” has been changed to “millimetres”]. One part of the drillings was mounted and polished for metallography, electron microprobe analysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS).…”

“…The precision and accuracy of the analyses were checked by measuring the silver‐alloy reference materials AGA1, AGA2 and AGA3 (cf. Birch et al ). An average composition was calculated by analysing each coin sample seven to ten times and normalising the single analyses to 100 wt %.…”

“…The standards AgRM1 and AgRM2 were routinely analysed as unknowns for accuracy and precision testing (cf. Birch et al ). Data reduction was carried out with the GLITTER™ software (Griffin et al ).…”

“…Precision and accuracy were checked by repeatedly analysing the NIST SRM981 standard (cf. Birch et al ). Pb–Pb model ages (derived from 206 Pb/ 204 Pb and 207 Pb/ 204 Pb ratios), 238 U/ 204 Pb (μ), 232 Th/ 204 Pb (ω) and 232 Th/ 238 U (κ) were calculated according to Stacey and Kramers ().…”