Authentication of some coins related to Achaemenid era based on archaeometallurgical studies

Despite the brilliant history of Iran, as one of the first promoters of coinage and the worthy collections of coins remained from ancient times, the cognitive study as an independent kind of science or as the historian supplement studies, was at less attention in Iran. Because of the metal resistance of the coins, they will be less affected by the environmental degradation factors comparing to the other historic and ancient artifacts; and in many cases, they remain in almost good quality. This advantage sometimes causes bugs in authenticity of some collections which were not obtained from the scientific archaeological excavations. In this research, 10 samples of silver coins related to the Achaemenian dynasty, were selected from a bigger collection of 57 pieces, which is kept in Pars Museum of Shiraz. This collection were recorded from the thieves of cultural relics in Marvdasht of Fars province in 2009, and was used for the elemental analysis at this study. As these coins are precious museum objects, sampling is very restricted, and the analytical method must be as non-destructive as possible. In different laboratories around the world, extensive methods of analysis are used in order to quantitative analysis of the elements, including particle induced X-ray emission spectroscopy (PIXE). This facility is available in Iran, so due to limitations in sampling and in using the other destructive methods in this study, PIXE analytical method was selected to be used in the analyzing process. Since the amount of metal elements plays an important role in determining the authentication of the Achaemenid coins, the percent of following elements were measured in the coin samples: Aluminum (Al), Sulfur (S), Chlorine (Cl), Calcium (Ca), Titanium (Ti), Manganese (Mn), Iron (Fe), Copper (Cu), Zinc (Zn), Silver (Ag), Lead (Pb), and, Gold (Au). This assessment was based on the assumption that the trace elements present in the sample could be considered as an indicator of the authenticity of the coins.