Analysing Treasure

Treasure is one of the most exciting words in the English language. It conjures up dramatic images of discovery. At the British Museum it certainly means discovery.

A treasure can be anything of historical importance, but it also has a long legal history in this country. The law of Treasure Trove dates back to at least the twelfth century. It allowed the king to claim any gold or silver that was found, if the rightful owners could not be traced.

In 1996, the Treasure Act created a new definition that now applies in England, Wales and Northern Ireland. This defines treasure items as finds that are at least 300 years old and which contain over 10% silver or gold or are groups of coins found together. Any objects associated with these finds are also defined as Treasure. Since 2003 groups of two or more base-metal prehistoric objects also count as Treasure.

Treasure items are offered to the British Museum and other museums to acquire and the finder and landowner are rewarded with their full market value. An item that is reported as potential Treasure under the Treasure Act often goes through a long process here at the Museum from its discovery to being acquired. But other items which do not count as treasure in this legal sense are also important in revealing our history.

The creation of the Portable Antiquities Scheme, and the creation of a network of finds liaison officers, in 1997 has allowed us to record these finds in a systematic way that adds to our understanding of the past.

Every find is an opportunity not only to examine a particular object, but also to add to our knowledge of the people and societies who made and used it. In spring 2004, as a British Museum curator was investigating a hoard found with a metal-detector on farmland near Oxford. He found an extremely rare third century coin bearing evidence of a previously unrecognised rebel Roman ‘emperor’, Domitianus, who was so little known that some scholars even doubted his existence.

A large team of people, from curators to scientists and conservators, is needed to study each treasure find. A quick and non-destructive way of working out an object's gold or silver content is by using X-ray fluorescence. This process determines the proportions of different types of metal and other elements the object contains.

Analysing an ancient object in this way is not just important for legal reasons. Discovering what it is made of can help us work out when and where it was made. Other techniques, such as examining an object under a scanning electron microscope (SEM) or with X-radiography can also provide information about how it was made.

The type of information provided by these scientific techniques is very important. Indeed, in some cases, the scientific analysis of a new discovery has provided the most important evidence for telling that discovery's story.

Conservators, trained to study and preserve ancient objects, also have a role to play in investigating new treasure finds. Objects need careful cleaning or they might deteriorate if they are not treated. This has to be done with great care and in the right way, or an object might be damaged or even destroyed.