A third century crisis? The composition and metallurgy of Roman silver coinage; Septimius Severus to Valerian and Gallienus.

The quality of Roman silver coinage is often taken an an index of the economic health of the empire, with a fall in silver content being taken as an indication of fiscal inadequacy. During the third century AD debased silver coinage came to dominate the currency system of the Roman world, coinciding with a period that historians have dubbed the 'third century crisis'. Between AD 194 and 260 the silver content of the coinage declined from just under 50% to less than 10%, and previous studies have proposed that this decline in quality was almost continuous. By about AD 260 new technologies had to be employed to make the coins look silvery and to disguise the fact that they were made mainly of copper. The continuous decline is thought to signify perpetual fiscal crisis, where revenues and resources could not match Rome's expenditure on its armies. It is generally thought that public confidence in the coinage waned, leading to inflation and the collapse of the monetary system. However, the evidence on which this account of monetary crisis is based is seriously flawed. Until AD 260 Roman mints were able to disguise the extent of debasement by deliberately enhancing the silvery surfaces of the coins using a technique known as depletion silvering, and previous analyses did not take this fact into account. Consequently we do not know anything for certain about the full extent of debasement between AD 194 and 260, or about the frequency of debasement. We do not know whether there were long periods of stability or even improvements during this period. While there can be no doubt that the silver content in AD 260 was much lower than in AD 194, the way in which the decline occurred - and thus the reasons for the decline - remain obscure. Previous work by the applicants on earlier periods have overturned the picture of continuous decline and perpetual fiscal crisis for those periods. It remains to be seen whether one of the cornerstones of the 'third century crisis', the collapse of the coinage, is a sustainable narrative.

The aim of the project is to analyse 2,250 Roman silver coins for the period AD 194 to 260, to determine not only the fineness of the coins but also to use minor and trace elements, and lead isotope analyses, to inform us about sources of raw materials and production technology. One explanation for the dramatic fall in the silver content of the coinage is that the Roman empire ran out of stocks of fresh silver. If this is so, evidence of recycling should be readily apparent. In addition, weight standards will also be scrutinised. These are important for drawing comparisons between different denominations of silver coinage, but they are also an important component of the concept of monetary standards. Finally, a study of hoards will look for evidence that the public was aware of changes made to the coinage.

The PI and Co-I form a strong interdisciplinary team of archaeometallurgist and ancient historian/archaeologist working closely together and with a successful track-record of synergistic collaboration on this topic going back over two decades.

To summarise: currently we know almost nothing about the condition of Roman silver coinage between AD 194 and 260, the period leading to the presumed collapse of the currency. Through interdisciplinary study, this project will bring together metrology, fineness standards, hoard evidence, metal supply and production technology to provide a comprehensive picture of Roman silver coinage at a crucial point in the monetary history of the Roman empire.

Beneficiaries:
1) The Curators in the institutions from which the coins to be sampled are drawn, including those of project partners. The analytical information will also assist other Museum Curators in assessing new acquisitions and detecting forgeries.
2) Conservation staff in all Museums possessing Roman silver-alloy coins will have access to accurate compositional and microstructural information that will be invaluable in condition reporting and assessment of remedial conservation and storage.
3) Coin collectors in general will have information about their coins that enables a more detailed understanding of their hobby and tools with which they will be better equipped to identify imitations and forgeries. There is already considerable interest in our research from the collector community, frequently informing debate on collectors' blogs and wikis (for example the Classical numismatics discussion board).
4) The general public have a great fascination with many aspects of the past and coinage is one of these; people relate to the concept of debasement and the methods for disguising it through modern coins and the changes being wrought on these (the recent change to copper-plated steel for example), and to inflation and how changes to the currency can affect it. Such readily accessible links with past are important ways to bring the public greater awareness of the value of scholarship and our Universities.

Potential impacts:
1) The work will affect the way in which the relevant archaeological materials will be handled by the UK government's Portable Antiquities Scheme (PAS) and how they are interpreted for the public. Coin hoards of the period AD 193-260 are common in the UK and form a significant proportion of finds registered by the Scheme.
2) The results of the project will be used to inform museum displays of coin hoards, e.g. explaining why certain sorts of coins were hoarded together, and to what monetary changes and/or crises they were responding. Specific examples of museum displays informed by the project are Taunton Museum (the Shapwick and Yeovil hoards) and Bath Roman Baths Museum (the Beau Street hoard) (see Project Partners).
3) Fostering better understanding and an appreciation of knowledge of the historical value of archaeological objects over their commercial value are important impacts.