The chemistry of ancient coins

As examples of hubris go, that of Hannibal (the Carthaginian general, not the fictional serial killer) takes some matching. And now German geochemists have added solid science to the evidence of historians and archeologists.

Hannibal, as documented by the Roman historian Livy, memorably led his Spanish army, aided by columns of war elephants, over the Pyrenees and the Alps, intent on sacking Rome.

The general successfully occupied much of Italy – although not Rome itself – for about 15 years, until he met defeat at the hands of the Roman general Scipio Africanus.

“Either we must stop fighting and disband our armies,” Livy has him saying before his Italian invasion, “or pursue our conquests elsewhere.

“By doing the latter, and by seeking plunder and renown from the conquer of other countries, the Spanish peoples will reap the harvest not only of peace but of victory.”

Research presented this week to the Goldschmidt geochemistry conference in Paris shows that, far from becoming enriched, Spain, newly conquered by avenging Romans, ended up losing much of its silver reserves, providing the raw metal for the coinage of Rome’s expanding empire.

A team of geochemists led by Fleur Kemmers and Katrin Westner from Goethe University in Frankfurt analysed 70 Roman coins dating from between 310 and 101 BCE. Roman conquered Spain, and thus acquired control of the country’s silver mines, around 211 BCE.

Using mass spectrometry, the German team showed that the lead content of most Roman coins changed after 209 BCE. Lead isotope concentration serves as a geological clock, identifying the origin or the ores used to extract silver.

Looking at four isotopes – ²⁰⁸Pb, ²⁰⁷Pb, ²⁰⁶Pb and ²⁰⁴Pb – the researchers established that Roman coins made before the Spanish conquest used silver that came from the same sources used by Greek and Sicilians in the same period.

By 211 BCE, however, the isotopes clearly identified the silver sources as being located in either southeast or southwest Spain.

“The defeat of Carthage led to huge reparation payments to Rome, as well as Rome gaining high amounts of booty and ownership of the rich Spanish silver mines,” says Westner.

“From 209 BC we see that the majority of Roman coins show geochemical signatures typical for Iberian silver.”

Defeat, by the way, did not mark the end of Hannibal’s career. He went onto enjoy a stint as a judge in Carthage, before taking up a role as military advisor to Antiochus III, ruler of the Seleucid Empire.

His new job went pear-shaped after the king was roundly defeated by the Romans, but Hannibal, who seems to have been made of Teflon, simply sped away and made a new gig for himself as naval chief in the court of Bithynia.

He was eventually betrayed to Rome by Bithynian double agents, and poisoned himself before he could be captured.