Highlights of the SILVER Project Research Achievements
The SILVER project has made significant strides in understanding ancient silver and lead sources, along with the flow of monetary resources. Here are the key highlights:
1. Isotope Data and Techniques:
The project generated extensive new data on lead and silver isotopes from over 700 ancient silver coins and around 200 lead/silver ores across the Mediterranean, including Greece, the Balkans, and the Western Mediterranean.
Silver isotopes in coins and ores are a groundbreaking discovery. The long-term interaction of groundwater with silver artifacts required the use of drilling techniques, which most curators now oppose.
Advances in mass-spectrometry, particularly MC-ICP-MS, have revolutionized lead isotope analysis, with the group playing a pioneering role.
2. Numismatic and Geological Discoveries:
Extensive sampling in museums in Athens, Brussels, Jerusalem, and Skopje addressed new topics such as early Iron Age chopped silver, Athenian coinage, Thraco-Macedonian coinage, the coinage of Alexander the Great, and more.
Lead isotopes can indicate potential sources of silver bullion, while silver isotopes can rule out unlikely sources, combining to identify actual silver-producing mines.
3. Historical and Geological Context:
The Mediterranean, a tectonically active zone, has abundant silver due to volcanic and subvolcanic activity from recent orogens (<80 million years). Silver is a present of plate tectonics to the Mediterranean.
Early sources of silver bullion, as early as 2600 BCE, were mainly around the Aegean Sea, with significant production in regions like the Taurus in Asia Minor, Sardinia, and Iberia.
4. Major Findings:
The project confirmed that the origins of the Achaemenid treasures, captured by Alexander the Great, were predominantly Aegean.
Silver coinage from the Aegean was crucial for trade development post-6th century BCE. The return of Greek mercenaries played a key role in the rise of democracy and the flourishing of Greek culture.
5. Isotopic Analysis and Recycling:
Lead and silver isotopes in coinage reveal whether silver was sourced from ores or recycled bullion. This principle, new to numismatics, shows that recycling played a role in the Roman economy, especially during the Second Punic War.
Principal Component Analysis of lead isotopes in silver coinage suggests Greek cities primarily used a single dominant bullion source with minimal external silver integration.
6. Regional Contributions and Techniques:
Gaul and possibly modern Tunisia were sources of silver before the Roman conquest.
The project introduced the analysis of platinum-group elements and gold in silver coinage, confirming that large-scale salt cementation was unlikely used by Athenians.
7. Innovative Databases and Algorithms:
SILVER developed two new databases: one for die studies to assess mint production and one for overstrikes to evaluate mechanical recycling without melting (
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A new three-dimensional search algorithm, validated by a chi-squared test, is a unique contribution.
