Ancient silver coinage formed the backbone of state finance in antiquity. The fineness of a coinage is often taken by historians to be a comment on the fiscal health of the issuing state, yet until now very little has really been known about its fineness and chemical composition. Many previous analyses were inadequate to answer key questions, because the samples for analysis were taken from the surfaces, or from just beneath the surfaces, of silver coins, and these are not representative of the original alloys used. The RACOM Project adopted a sampling method to overcome this problem, resulting in a large dataset of reliable analytical results for the composition of these coinages.
The historical period covered by the RACOM Project, from c. 150 BCE to 64 CE, is important in the economic development of the Mediterranean world. It witnessed a major increase in long distance trade and probably also economic growth and a rise in per capita income. Flows of precious metals to Rome and other important centres of power helped finance Roman expansion. It is generally thought that greater monetary integration of the Mediterranean accompanied Roman conquests; however, the continuation of local and regional silver coinages of traditional type challenges the idea of the spread of Roman coinage as an instrument of imperialism.
The objective has been to examine financial and monetary strategies during that time through detailed analyses of the chemical composition of all major silver coinages of the period, taking samples from deep within the coins (where the original 'recipe' used for the coinage alloy is preserved). The samples are then analysed by two complementary, well-established techniques (microwave-plasma atomic emission spectrometry; and inductively-coupled plasma mass spectrometry).
Taking drilled samples from museum coins is not always possible, and the project has also evaluated two new, minimally destructive, or non-destructive, techniques to see how they compare with established protocols: muon x-ray emission spectroscopy; and laser ablation inductively-coupled mass spectrometry.
