Wed, 18 October, 2023
TWI has been supporting Cardiff Museum in the investigation of a Roman coin hoard found by two metal detectorists in Conwy Valley, Wales. Two hoards were found, with the larger hoard being found in a ceramic vessel that contained 2,733 coins, a mix of silver denarii minted between 32 BC and AD 235, as well as silver and copper-alloy radiates struck between AD 215 and 270. We offered to use our state-of-the–art X-ray Computed Tomography (XCT) system to scan the ceramic vessel, to see whether more information could be gleaned before extraction of the coins began.
(Image © Amgueddfa Cymru – Museum Wales)
Consultant engineer at TWI, Ian Nicholson, said, “Our main focus is to provide our services for industry. However, we also like to support non-industry projects and offer a wider benefit. Radiography was the only inspection technique that had the potential to volumetrically reveal the inside of the coin hoard without damaging it. Our state-of-the-art 450kV/1A Computer Tomography inspection equipment uses high X-ray energy to penetrate thick metals, which is typically four times greater than the X-ray energies that dentists and hospitals use. We found the inspection challenge interesting and valuable. When Amgueddfa Cymru - Museum Wales approached us - it was a nice change from inspecting aeroplane parts. Using our equipment, the digital radiography helped allow us to determine that there were coins at various locations in the bag. The coins were so densely packed in the centre of the pot that even our high X-ray energies could not penetrate through the entire pot. Nevertheless, we could reveal some of the layout of the coins and confirm it wasn’t only the top of the pot where coins had been cached.”
Example 2D image slice extracted from acquired XCT data volume
More information about the coin hoard can be found here and you can find out more about our radiography testing services here.