Don't ancient coins belong in museums?
Ancient coins were mass-produced on an industrial scale, struck quite literally in their billions, and surviving today in their millions. Needing to pay his sizable forces prior to the battle of Actium in 31 BC, Mark Antony struck a single series of an estimated 25-35 million silver coins; these "legionary denarii" circulated for hundreds of years into the later empire and with tens of thousands still surviving, the series remains popular with collectors to this day. Modern die studies have shown that the Roman mint would routinely strike many million coins in a particular series.
It is therefore important to remember that, while impressive in their artistry and sometimes fondly called “monuments in miniature”, ancient coins are not in fact unique monuments, statues or inscriptions, and they should not be equated as such. Coins are and always were portable items of economic exchange, used by people at every level of society.
The scientific study of coins and currency, known as numismatics, predates other disciplines like archaeology and anthropology by centuries yet still remains one of the more obscure academic fields. Even among history specialists, numismatics is seen as an esoteric area of study. Coins are rightly valued by the archaeologist for the precise dating evidence they can provide for a site but there may be some truth in the aphorism that says "to the archaeologist, coins are just well dated pieces of metal". For all their obvious links, the sciences of archaeology and numismatics have long operated with surprising independence from each other. In such a multidisciplinary field, it is understandable that most archaeologists approach coinage with only a broad appreciation of historical "currency" rather than with any detailed understanding of the subject, even within their era of specialism. Precise identification and understanding has always been thought best left to the eccentric numismatist, with coins usually confined to museum storerooms at the earliest possible moment.
Many museums around the world have vast coin collections that have been well studied and published. Though they are all historically valuable windows into the ancient world, by their nature coins are small, difficult to display effectively and hard to contextualise for the general public. As such, institutions only ever display a tiny amount of their collections. The British Museum for example displays a fraction of 1% of its ancient coins and as with many museums, storage and maintenance is a continuing challenge. The idea that a museum would want to secure every newly discovered ancient coin for its collection could not be further from the truth. Nowadays, only the most outstanding coin discoveries with exceptional historical value would ever interest a museum, and many are actively downsizing their collections.
Ancient coins are often found in large hoards, sometimes numbering in the tens of thousands; once they have been diligently recorded and documented by experts there is little need for museums to hang on to them and they are promptly released to the public market. Of course, there are those coins that might have the combination of rarity and historical significance that a museum may want to acquire, or a dazzling hoard that adds to our economic understanding of the ancient world - yet even then, museums may only want to keep part of the hoard for display. The openness of the UK Treasure Act (1996) and Portable Antiquities Scheme (1997) which allow coin finds to be fully recorded and afterwards released to the public market, incentivises finders to declare their discoveries, increasing our body of knowledge and working to the mutual benefit of both academics and hobbyists.
Museums may once have been the only place an ancient coin could be kept safe and available for academic study but this is no longer the case. Private collectors go to great lengths in effort and expense to store their beloved collections carefully, investing far more in modern storage methods and techniques than most museums can hope to; institutions do their best with the often limited resources at hand but it is sadly worth noting that many an ancient coin has rotted from corrosive bronze disease in a neglected Victorian-era museum coin cabinet over the years. As with other hobbies like astronomy, a huge amount of research is now completed by amateurs and exciting discoveries are regularly made by enthusiasts with an encyclopedic knowledge of the field. Collectors do much of the work in identifying new types and finding provenances for coins, adding to their heritage and conservation - and far from selfishly hiding their artefacts in locked vaults, collectors are usually very eager to record, share and celebrate their collections, working closely with academic institutions and offering items on long-term loan for exhibition.