New Analysis of Medieval Coins Reveals a Surprising Place of Origin

Between 660 and 750 AD, Anglo-Saxon England began to revive the use of silver coins, breaking from their traditional reliance on gold. To date, archeologists have discovered around 7,000 silver pennies from this period – a number nearly on par with those recovered from the rest of the Anglo-Saxon period (450 to 1066 AD) combined.

The evidence for a sudden boom in silver coinage is clear, but the question of where all this silver came from has puzzled historians for decades.

Now, researchers from the University of Cambridge, University of Oxford and the Vrije Universiteit Amsterdam have solved this mystery, thanks to modern advances in materials analysis.

“There has been speculation that the silver came from Melle in France, or from an unknown mine, or that it could have been melted down church silver,” said Rory Naismith, study co-author and a professor of early medieval English history at the University of Cambridge. “But there wasn't any hard evidence to tell us one way or the other, so we set out to find it.”

Analysis finds dramatic split in the origins of early silver coinage

The study looked at 49 medieval coins kept in the collection of the Fitzwilliam Museum, Cambridge. These coins were minted in locations across England, Frisia and Francia – a region stretching across modern-day France, Belgium and the Netherlands – between the years 660 to 820 AD.

The team chose to analyze the coins using combined lead isotope analysis and trace element analysis – a method previously unapplied to coins from this era.

The trace element analysis was performed in the laboratory of Dr. Jason Day at the University of Cambridge. Following this, the coins were assessed using a portable laser ablation technique pioneered by the Vrije Universiteit Amsterdam.

Their method generates microscopically small coin fragments that are collected on Teflon filters and used for lead isotope analysis. This yields high precision results while being far less invasive than traditional lead isotope sampling methods, the researchers say, which is vitally important when dealing with historical artifacts.

The team found a strikingly clear split in the chemical makeup of coins minted in the earlier period (660 to 750 AD) compared to those from a later Anglo-Saxon period (750 to 820 AD).

Early silver coins traced to Byzantine bullion

Twenty-nine of the tested coins – all from the earlier period – were found to contain relatively high amounts of gold (0.6 to 2%) and a consistent isotopic signature, indicating no significant regional variations among them.

The coins’ elemental and isotopic characteristics were not found to be a match for any known European ore sources. There were also no similarities with late Roman coins or objects, the researchers say, meaning that the coins were not made from local mines or recycled Roman silver. Remarkably, the chemical and isotopic signatures were a close match for silver from the Byzantine Empire, dating from between the 3^rd to early 7^th centuries.

“This was such an exciting discovery,” Naismith said. “I proposed Byzantine origins a decade ago but couldn’t prove it. Now we have the first archeometric confirmation that Byzantine silver was the dominant source behind the great seventh-century surge in minting and trade around the North Sea.”

Study author Dr. Jane Kershaw, an associate professor in archaeology at the University of Cambridge, added: “These coins are among the first signs of a resurgence in the northern European economy since the end of the Roman Empire. They show deep international trade connections between what is now France, the Netherlands and England.”

But what was Byzantine silver doing in Western Europe? Trade and diplomatic relations between these regions were at a low point during this period, so intentional trade is an unlikely explanation. Instead, the researchers believe that the Byzantine silver must have come to Europe much earlier, but wasn’t melted down to be used as coinage until the late 7^th century.

“Elites in England and Francia were almost certainly sitting on this silver already,” Naismith said. “We have very famous examples of this, the silver bowls discovered at Sutton Hoo and the ornate silver objects in the Staffordshire Hoard.”

“These beautiful prestige objects would only have been melted down when a king or lord urgently needed lots of cash,” Kershaw added. “Something big would have been happening, a big social change.”

Later coins show Charlemagne’s influence in the region

Not all of the silver coins were of Byzantine origin – approximately twenty of the coins from the later half of the study period had a very different elemental makeup. These coins contained very low levels of gold, which is characteristic of silver mined at Melle, a town in modern-day France.

Previous historical studies have shown that Melle was an important mine in Francia during their Carolingian dynasty (751 to 887 AD), but historians did not know when exactly the mine began to rise to prominence.

“We now know that after the Carolingian dynasty came into power in 751, Melle became a major force across Francia and increasingly in England too,” Naismith said.

As to why this Melle silver ended up in Anglo-Saxon coinage, the researchers suggest that it could be linked to the start of Charlemagne’s reign. There are historical records showing that Charlemagne’s grandson, King Charles the Bald, gave every mint under his power a gift of silver when he rose to the throne as a way to kickstart the production of coins in his own image. “I strongly suspect that Charlemagne did something similar with Melle silver,” Naismith said.

Charlemagne’s diplomatic relations with England’s King Offa of Mercia could have seen this newly minted Melle silver also flow into Anglo-Saxon hands, the researchers say. Surviving letters between the pair have passages that mention trade, with both rulers having also entered a trade embargo when a betrothal between their children was abandoned.

“There was a lot of communication and tension between Charlemagne and Offa,” Naismith explained. “Offa wasn’t in the same league, his kingdom was much smaller, he had less power over it, and he certainly didn’t have as much silver. But he remained one of Europe’s most powerful figures who was outside of Charlemagne's control.”

“When commodities are only in certain places in limited quantities, questions of power and national interest will always come into play,” Naismith said.

Reference: Kershaw J, Naismith R, d’Imporzano P, Merkel S. Byzantine plate and Frankish mines: the provenance of silver in north-west European coinage during the Long Eighth Century (c. 660–820). Antiquity. 2024. doi: 10.15184/aqy.2024.33

This article is a rework of a press release issued by the University of Cambridge. Material has been edited for length and content.