Using the most advanced techniques for analyzing the surfaces of materials, a team of researchers has shed light on the coin-making practices of the Roman Empire and the manner in which Roman coins have corroded over the past 2,000 years.The first part of the article has technical details, but then it goes on to discuss how the technology demonstrates the devaluation of the denarius as the Roman empire declined. Then there is this:
The study by Lehigh chemical engineers and materials scientists demonstrated that low-energy ions, x-rays and laser lights can be used to analyze archaeological objects without damaging them. And it yielded clues about the environment to which the coins, and the people who handled them, were exposed.
Several years later, Notis teamed with Aaron Shugar, a former postdoctoral researcher at Lehigh, and two other scientists in a study of 700 shekel and half-shekel coins that were minted in the ancient Roman city of Tyre (located in modern-day Lebanon) and recovered half a century ago in Israel.Cross-file under Technology Watch and Phoenician Watch. Note the little extra story at the end of the quote about using the technology to authenticate Philistine coins. A couple of recent PaleoJudaica posts on the denarius are here and here. Shekel and half-shekel (etc.) coins have come up as well. Some posts are here, here, here, here, here, here and links.
The researchers used a handheld X-ray fluorescence (XRF) unit, irradiating the coin with an X-ray and measuring the rays reflected back to determine the coins’ overall composition. They confirmed the XRF results with electron probe bulk microanalysis.
The Tyrian shekels, Notis said, circulated during the time of Jesus, when the temple in Jerusalem was the central meeting place for Jews living in the Roman Empire. “Every year, Jews were required to pay a tax to the temple,” he said. “The temple accepted only coins minted in the town of Tyre, which was known for the purity of its silver.
“We wondered what had happened to the silver content of the coinage. Two main hoards of coins from Tyre have been found. One was near Haifa in the village of Isfiya, the other was near Qumran, adjacent to the site where the Dead Sea Scrolls were discovered.” Several jars of Roman coins in mint condition, similar to the coins investigated in the Lehigh studies, were also found with the Dead Sea Scrolls.
The XRF analysis, said Notis, revealed the overall silver content of each Tyrian coin in two minutes. “We analyzed 700 coins in 24 hours using a handheld XRF unit. We plotted the bulk silver content versus the year of the date of the coin on a graph.
“We found much the same results that Pense had found—coins were made of 90-plus percent bulk silver until 44 B.C.E. when the Roman civil wars began. All of a sudden, the silver content dropped dramatically until Augustus Caesar took over.”
Notis and Shugar also used XRF to examine coins minted by the Philistines between 500 and 400 B.C.E.
“We were able to spot fakes immediately,” said Notis, “because they had a silver content of only 46 percent, compared to the 95 percent silver content of the authentic coins.”