Elemental Analysis of Piruz, the Sassanid King, Coins by Using PIXE Technique, A case study of Piruzgat Treasure coins, discovered in Tis Village, Chabahar

Abstract The ruling era of Piruz, the Sassanid king, must be considered one of the most challenging historical periods. The reasons of political-economic tensions could be traced in drought, successive and long wars, the capture of Iran from two different directions, and, ultimately, the tribute paid by Iranians to Hephthalites. Generally speaking, the coins belonging to Piruz ruling era were minted in four different forms throughout four different periods of time in various places; therefore, the elemental analysis of the metal used in these coins provides us with valuable information about the economic-political conditions, the type of mines, and the minting process of the coins. Hence, to conduct an elemental analysis of these coins, the non-destructive PIXE test was employed. The data of the present study is extracted from 41 non-repetitive coins out of 183 coins belonging to Piruzgat Treasure discovered in Tis, Chabahar, in 1380. However, unlike the supposition that the coins alloy must have been low due to the political tensions of that era, PIXE proved that the alloy has always been above 96 percent on the average. The amount of gold in these coins has always been at an average of one percent. Since this value ranged from 0.2 to 1.5 percent, the use of Cerussite mines in that period is proved which is also confirmed by the presence of lead in some coins. Only one type of coin (120,GOM) had a low amount of gold (0.15 percent) which could be the sign of using Galena mines in the 4th period of the ruling era. But the low amount of copper could signify a hurry in minting and inadequecy of silver extraction as a result of not using copper in these coins, existence of lead, and elemental variety especilly in the second and third periods. Keywords: PIXE; Numismatics; Piruz, the Sassanid King; Piruzgat; Sassanian.