Coins invisible to the human eye have been discovered using a new x-ray technique. Scientists have produced 3D images of a corroded mass of ancient coins discovered in Britain hidden in a pottery vessel.

Silver denarius of Trajan

Silver denarius of Trajan

Silver denarii from the time of Marcus Aurelius, Vespasian, Trajan and Hadrian were all jumbled together and came to light when the pot was subjected to an x-ray technique designed for a completely different purpose -scanning Rolls Royce turbine blades for flaws.

What is known as the Selby hoard of Roman coins was discovered by an amateur in a field near Selby Yorkshire using a metal detector. A coin hoard is typically thought to be a stash of money that has been hastily hidden away in the expectation of war or civil disturbance and lost by the owner due to death or other misfortune. Misers, such as the fictional Silas Marner, also hoard money. Apparently, civilization hasn’t changed much. With banks and the stock market being suspect, today’s citizens may be going back to burying their money in coffee cans in the back yard. Romans buried their money in clay pots, perhaps not for safekeeping however. Eleanor Ghey, the archaeologist studying the find, hypothesizes that the coin-containing pot was part of a ritual offering of both food and money since chaff was found mixed with the coins.

The new x-ray method allowed investigators to identify and even date the coins found at Selby without damaging them, an ability especially important since the coins were already corroded. The new process can reduce identification time to hours instead of the months a conservator would need. After x-raying the pot and identifying the coins, the researchers extracted them from the pot and re-identified them the old fashioned way, proving the legitimacy of the new technique.

Southampton University and the British Museum collaborated to deliver the x-ray technique that takes thousands of two dimensional scans that are used to produce the 3D animation. The video can be seen here. The coins will be on display in the museum.

Roman coins vary in value. e-Bay lists a Marcus Aurelius denarius for $61. Rare coin dealers on the internet are offering denarii for £40 – £410 ($62 – $636) depending on the reign or subject. If you are really lucky and find a silver denarius of L. Clodius Macer, struck at Carthage circa A.D. 68, one sold for $88,500 this January. Now where did I put my old metal detector?