New Insights into Ancient Greek Coinage: Exploring Gold Purification Techniques

Attica and Cyclades coins from ancient Greece are famous for their historical and cultural significance. These coins are unique because of their low gold content, and a team of researchers is using inductively coupled plasma–mass spectrometry (ICP-MS) to analyze them (1). The team looked at platinum-group elements (PGEs) and gold in 72 silver coins from various ancient civilizations, including Greece, Rome, India, medieval Europe, and colonial Spanish Americas (1).

Illyria and Central Greece – Attica silver coin tetradrachm 454-404 BC, helmeted head of Athena right, olive sprig and crescent behind standing owl, | Image Credit: © Yaroslav - stock.adobe.com

ICP-MS was used to measure the concentrations of PGEs and gold in silver coins, providing valuable insights into the coinage and metallurgical techniques of the past (1). The results of this research offer a fresh perspective on the composition and origin of ancient Greek and Hellenistic coins, as well as those from other ancient cultures. The findings reveal that the behavior of PGEs and gold in these coins is closely aligned with their respective positions in the periodic table, shedding light on the coin production processes employed by various civilizations (1).

The researchers used quadruple ICP-MS to analyze platinum-group elements such as platinum (Pt), iridium (Ir), ruthenium (Ru), palladium (Pd), and rhodium (Rh). They found distinct patterns in these silver coins. For example, the most volatile elements, such as Rh, were found at or below the detection level, possibly because of evaporation during the smelting and cupellation processes (1). Meanwhile, for Ru and Irdemonstrated variations in coinage consistent with these properties (1). The soluble elements Pd and Pt exhibited patterns in the coins that align with their solubility characteristics.

One intriguing discovery was the dichotomy of the Ir:Au ratios, which challenged preconceived notions about salt cementation and its effect on gold. Iridium was believed to be lost in gold during salt cementation, but the ratios indicated that there could be regional variations in ore genesis conditions, such as the chlorinity of hydrothermal solutions (1).

The study pioneers a comprehensive approach to understanding ancient coin metallurgy, providing insight into how elements were selectively incorporated into coinage. The results challenge long-standing assumptions about the composition of ancient coins, particularly in the case of Athenian coinage, where salt cementation of gold was considered a source of silver (1).

This research deepens our understanding of ancient metallurgical techniques. By analyzing silver coins from various civilizations, the researchers showed through using ICP-MS offers valuable insights into the historical and cultural factors that shaped the coinage of the past (1).

This article was written with the help of artificial intelligence and has been edited to ensure accuracy and clarity. You can read more about our policy for using AI here.

Reference

(1) Albarede, F.; Malod-Dognin, C.; Telouk, P. Platinum-group elements and gold in silver coinage and the issue of salt cementation. J. Anal. At. Spectrom. 2023, ASAP. DOI: 10.1039/D3JA00112A