Sending Laurion Back to the Future: Bronze Age Silver and the Source of Confusion

Abstract

Silver-bearing lead ores at Laurion in Attica were considered to have been first exploited with the introduction of coinage sometime around the birth of Classical Greece. However, in the late 20th century this chronology was radically revised earlier, to the Bronze Age, largely supported by lead isotope analyses (LIA). Here, we acknowledge that lead and silver metallurgy emerged from the earliest times but we propose that any correlation between these metals in the archaeological record is not a consequence of a geological association between lead and silver in ores such as galena until the middle of the first millennium BCE. We suggest that ancient metallurgists recognised that silver minerals (such as horn silver) dispersed in host rocks could be concentrated in molten lead and that LIA signatures of Bronze Age silver artefacts reflect the use of exogenous lead to extract silver, perhaps applying processes similar to those used to acquire silver in Bronze Age Siphnos. We further propose that lead from Laurion used for silver extraction resulted in the inadvertent transfer of its LIA signature (probably aided by roving silver prospectors) to silver objects and metallurgical debris recovered around the Aegean. New compositional analyses for the Mycenaean shaft-grave silver (c. 1600 BCE) support these conclusions. We believe that reverting to the mid-first millennium BCE for the first exploitation of silver from argentiferous lead ores is consistent with the absence of archaeological evidence for centralised control over Laurion until the Archaic period, the paucity of lead slag associated with silver-processing debris at Bronze Age sites, the scarcity of silver artefacts recovered in post-shaft grave contexts at Mycenae and throughout the Early Iron Age Aegean, the few Attic silver coins with LIA signatures consistent with Laurion until after 500 BCE and a single unambiguous mention of silver in the Linear B texts.

Approaches to interrogate the erased histories of recycled archaeological objects

“…It is also consistent with the density plot of Athenian coins (Figure 4), which are believed to derive from the silver ores of Laurion (Gale et al, 1980). This further supports that the vertical mixing line in Figure 4 is a consequence of inadvertent mixing of gold, as gold concentrations are extremely low in silver derived from argentiferous galena (usually < 0.1%Au) (Wood et al, 2021).…”

Other ways to examine the finances behind the birth of Classical Greece

“…A major problem for archaeological science, however, is that by accepting that silver could have been extracted by adding exogenous lead, provenance investigations can be frustrated; that is, if the lead used to collect silver derived from a different geological location to the silver ore, the extracted silver will have a lead isotopic signature associated with the location of the lead ore rather than the silver source (Wood et al, 2017b). In fact, the prevalence of Laurion LIA signatures in objects and technical debris recovered around the Aegean (Wood et al, 2021) indicates that Laurion lead was the silver collector of choice. In effect, lead from Laurion (and its lead isotopic signature) may have been carried by ancient 'prospectors' to use when they encountered dry silver ores worth exploiting.…”

A Multivariate Approach to Investigate Metallurgical Technology: The Case of the Chinese Ritual Bronzes

“…These six ratios account for 92.1% of the total logratio variance STEP 71.4%. Although Au can be associated with silver in lead ores (and zinc can be associated with lead ores, see Step 1), the absolute concentrations of gold in the bronze vessels are much higher than gold usually associated with silver in lead ores: that is, the bronzes have gold to silver ratios that are generally an order of magnitude higher than that usually found in argentiferous galena (Wood et al, 2021). This could suggest that gold enters the system from more than one source.…”

“…as the proportion of one component increases, the proportions of other components must decrease) and therefore cannot be used to conclude that silver is solely attributable to the addition of lead. In fact, the concentrations of silver in the bronzes are higher than the few tenths of a per cent usually associated with lead from galena ores (Wood et al, 2021), and copper sources such as tetrahedrite (fahlore) are well known to be associated with silver (Cronshaw, 1921: 12;Pernicka et al, 2016). Nonetheless, regardless of whether the silver derives from the lead and/or the other components, its variation is dominated by fluctuations in the compositional recipe.…”