Scientific Investigations on Roman Silver Coins of the Emperor Trajan (AD 98–117)

The rule of the Roman emperor Trajan (AD 98–117) has always attracted specific interest among financial historians, since written sources provide us with several important pieces of information concerning the finances of the state during his reign. Therefore, the Trajanic period may be regarded as one of the key periods for the modern understanding of the economy of the Roman principate in general. In order to evaluate the financial policy of an ancient state, it is necessary to study the composition of the alloys of the precious metal coinages issued under the control of the state’s government. In the past, this has often been carried out using energy dispersive x-ray fluorescence analysis (ED–XRF) – also in the case of Trajan’s silver coins (Walker 1977). However, such investigations had to be performed on the surfaces of the coins, as the analyses had to be carried out on pieces of museums ’ collections. This means, however, that the results obtained are not reliable at all, since corrosion usually occurs on ancient excavated objects, as has already been documented repeatedly: e.g. Linke et al. 2002 and 2004. Because of this phenomenon the determination of the chemical composition of the coin’s core is essential, which means that either sample material has to be taken or the coin has to be cross-sectioned. In the few cases in which this has been done, n