Silver Isotopes in Silver Suggest Phoenician Innovation in Metal Production

Abstract

The current study presents Ag isotopic values of 45 silver artifacts with known Pb isotopic composition from the Southern Levant. These items originate from seven pre-coinage silver hoards, dating from the Middle Bronze Age IIC to the end of the Iron Age (~1650–600 BCE). These are the earliest silver artifacts analyzed for Ag isotopes; all former studies were performed on coins. All the sampled silver in this study contains relatively unfractionated Ag (−2 ≤ ε109Ag ≤ 1.5) that was more likely produced from hypogene, primary Ag-bearing minerals (e.g., galena and jarosite) and not from native, supergene silver. Four of the sampled hoards containing silver from Anatolia and the West Mediterranean (Iberia and Sardinia) are associated with the Phoenician quest for silver (~950–700 BCE). A significant amount of this Phoenician silver (12/28 items) plots within a narrower range of −0.5 ≤ ε109Ag ≤ 0.5. This is in contrast to non-Phoenician silver, which mostly underwent some degree of fractionation (16/17 items ε109Ag ≥ I0.5I). The results suggest that while all silver was exploited from primary ore sources, the Phoenicians dug deeper into the deposits, reaching ore minerals that did not undergo any weathering-associated fractionation. The results also call for further investigation regarding the influence of sealing and bundling in silver hoards on post-depositional fractionation of Ag isotopes.

Narrowing provenance for ancient Greek silver coins using Ag isotopes and Sb contents of potential ores

“…Histogram of ε 109 Ag values in silver coinage (this work,Desaulty et al, 2011Desaulty et al, , 2013 Albarede et al, 2016 Albarede et al, , 2021. Hacksilber analysis byEshel et al (2022) are consistent with this range. The ε 109 Ag values of galena ores are from this workand Milot et al (2022).…”

“…Europe, colonial Spanish Americas) is extremely narrow (ε 109 Ag = 1 to +1; Desaulty et al, 2011;Desaulty and Albarède, 2013;Albarède et al, 2016Albarède et al, , 2021; Hacksilber from the ancient southern Levant: ε 109 Ag = 2 to +1; Eshel et al, 2022), the range is much broader for silver ores (-8 to +9; Mathur et al, 2018;Arribas et al, 2020;Wang et al, 2022) and for Iberian galena samples (ε 109 Ag = 8 to +3; Milot et al, 2021a). This stark contrast offers the potential to differentiate Ag-bearing ores that actually may have produced metal used for coinage from other mines which did not contribute to coin production.…”

Identifying episodes of recycling in the archaeological record

“…Unfortunately, Ag isotopic variation appears to be controlled by ore genesis rather than geology (Arribas et al 2020), making them of marginal interest for provenance studies (Milot et al 2022). Despite this limitation, some research groups have continued to pursue silver isotopes for provenance investigations (Albarède et al 2021;Eshel et al 2022;Vaxevanopoulos et al 2022). Galena ores from Iberia, for example, have been proposed by Jean Milot et al (2022) as the source of silver for Roman denarii of different origins and ages of minting, based on the narrow range of ɛ 109 Ag (that is, the deviation per 10,000 of the 109 Ag isotope of a given sample relative to the U.S. National Institute of Standards and Technology [NIST] 978a Ag standard), compared to the wider range of ɛ 109 Ag in silverbearing base metal (Pb, Zn, and Cu) ores.…”

“…Essentially, recycling can explain the narrow range of silver isotope values with respect to the standard (that is, ɛ 109 Ag) not only for Roman coins (Milot et al 2022) but also for Hellenistic, medieval and modern silver coins and hacksilver (Desaulty et al 2011;Desaulty and Albarede 2013;Albarède et al 2016;Albarède et al 2021;Milot et al 2021;Eshel et al 2022;Milot et al 2022;Vaxevanopoulos et al 2022) which all report ɛ 109 Ag values that have narrower ranges than those reported for hypogene and supergene ores (Mathur et al 2018;Arribas et al 2020). This would cast doubt on the regions in Iberia identified for the provenance of the silver used for Roman coinage (Milot et al 2022), or at least the procedure used to arrive at this provenance.…”