Researchers map metallic DNA of old coins

Canadian researchers have discovered a technique that enables them to link silver and gold found in ancient Greek and Roman coins back to the Mediterranean locations where the source metal was mined.

Researchers at McMaster University in Ontario are mapping the “metallic DNA” of ancient Greek and Roman coins, according to CTV.

“They have developed a technique that makes it possible to determine the precise metal content of ancient coins by bouncing subatomic particles off their surface. Repeated thousands of times over the course of weeks, the process begins to reveal exactly what the coin is made of,” CTV reported.

Once the “metallic fingerprint” is complete, researchers can begin to link the coins back to the Mediterranean locations where the metal was mined, said Spencer Pope, one of the researchers leading the project.

Pope told CTV that as researchers begin to understand the origin of the metal used in the coin, they’re better able to understand economic trade routes and particular patterns of trade and exchange in antiquity.

The long-term goal is to create a database available to researchers, archeologists and historians around the world.

Pope and his colleagues are studying coins on loan from the McMaster Museum of Art in Hamilton, Ontario. Most are Greek and Roman coins, some dating back 2,500 to 3,000 years.

By analyzing numerous coins the researchers are able to piece together whether the silver or gold bullion used to make the currency was acquired in large batches, piecemeal, or whether the coins were simply restruck from other coins, CTV reported.

“By understanding the composition we can begin to make conclusions about trade, the administration of the Greek city, whether this was a one-time effort from a leader of the city to secure a vast supply or constant efforts over a long period of time. And these questions can begin to inform us about the origins,” Pope said.

Pope and his colleagues have mapped the contents of about 20 coins to far, with each taking about a month. Among the batch is a Roman coin dating back to the Punic Wars between Rome and Carthage, between 146 and 264 BCE.

The period was one of great financial strain for Rome as it struggled to fund the war, a fact that is reflected in the coins minted during the era.

“A coin dating from this period has been determined to have a lot of base metals included,” Pope said. “It’s a silver coin, and if you look at it from the exterior it has the silver colour and it shines like a silver coin. But it has a lot of elements added, tin, lead, and this is what we can reconstruct as ancient inflation.”

“Coins dating back to when Sicily was under Greek rule also tell a fascinating story,” CTV reported. “Because the area was poor in natural resources and had none of its own gold or silver, the mint relied entirely on restriking other coins to create currency.”

When those restruck coins are analyzed, researchers can draw informed conclusions about where the original coins came from.

Through their research, Pope and his colleagues hope to create a database that can be accessible by coin researchers around the world.

In theory, an ancient coin found in a shipwreck in the Mediterranean, for instance, could then be analyzed and its metallic DNA could be connected to the source mine where the metal actually came from.

(Hat tip: A Blog About History)

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