Elemental Analysis of Piruz, the Sassanid King, Coins by Using PIXE Technique, A Case Study of Piruzgat Treasure Coins, Discovered in Tis Village, Chabahar

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 research questions are: What is the period of Piruz’s economic power with the coinage index? Given the elemental breakdown of these coins, he described the type of mines, how to extract the metal from the ore, and the coins’ grinding? 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 inadequacy of silver extraction as a result of not using copper in these coins, existence of lead, and elemental variety especially in the second and third periods.
  
Introduction
The period of Sassanid Piruz’s reign must be regarded as one of the busiest periods in history, Because of the drought, the prolonged wars, the occupation of Iran by two different factions and finally Iranian’s tribute to Heptalians. Because of this, much historical information was not available from that time, and everything that is short, sometimes scattered and without a turning point. So the coins of that era can be considered a valuable document and the best archaeological data Because they belong to the same time and, like other books, were not created for the purpose of re-reading, Therefore, elemental analysis of coins of this period was the main basis of this research.
The research questions are: What is the period of Piruz’s economic power with the coinage index? Giv-en the elemental breakdown of these coins, he described the type of mines, how to extract the metal from the ore, and the coins’ grinding?
In this study, Pixie technique was used to study coins because of its speed, high accuracy and non-destructiveness. This method is a common method for elemental analysis of homogeneous samples; in homogeneous samples its components are uniformly dispersed. And if samples are non-homogenous, other methods can be used, such as micro pixies, but coins are homogeneous.
The data in this article are the coins of the victorious treasure. This treasure contains 183 pieces of coins from the Sassanian victor (459-484 AD) Which in 2001. Near the ancient site of Pirouzgat (Pirouz Fortress) located in the village of Tis, Chabahar, were found by workers during road construction, and these coins are now kept in the Grand Museum of South East (Zahedan Museum) and the Chabahar Local Museum.
In general, Sassanid Piruz’s coins have been minted in four different ways in four different times during his reign, and coins of this treasure are not out of the circle.A total of 41 non-duplicate coins were se-lected from this collection (with an approach of each coin and a specimen from each mint).
The decomposition of the elements in these coins can provide valuable information on socio-economic conditions, to allow a better analysis of the conditions of that period. In this article, Pixi’s experiment is attempted to examine the four types of Sassanian victorious coins that have been minted in four differ-ent times.
 
Identified Traces
Contrary to the notion that the coinage of victorious coins should have been lowered by successive wars, droughts, and so on, it did not, and by pixel experiment, the Composition of these coins was, on average, always above average 96%.
The amount of gold in these coins has always been 1% on average, and since it was between 0.2 and 1.5%, it indicates the use of Cerussite mines in that period.؛ Only one coin (GOM 120) has a low gold value of 0.15% which could be the reason for the use of Galena mines in the fourth round of the victo-ry.
The amount of copper present in the first and fourth species is higher than 1.2% on average, but in the second and third species the average copper content is less than 1%. Given the amount of copper pre-sent in more than 1% of the coin, this indicates that the coin is alloyed for strength. It can be conclud-ed that in the first and fourth periods of the victorious rule, the quality of coinage was given more im-portance than the second and third coins. This may have been the result of political and economic ten-sions. Of course, copper alloys were generally subjected to spatial and temporal conditions during that period and were performed at any average interval.
Few of the second to fourth types of coins show less than 1% lead, which in addition to confirming the use of lead mines for silver extraction, in some ways indicates insufficient haste and inaccuracy in the extraction of silver.
Elemental variation in the second and third species is very high, which can be due to the use of differ-ent mines, the inaccessibility and inaccuracy of silver extraction. Or these metals come from the help of the Roman government in Iran. Although elemental variation is found on the fourth type of coins, it is not strongly the second and third species. This may be due to the relative improvement in political and economic conditions in the fourth period of Piruz’s rule.
 
Conclusion
The period of Sassanid Piruz’s reign must be regarded as one of the busiest periods in history,Because of the drought, the prolonged wars, the occupation of Iran by two different factionsand finally Iranian’s tribute to Heptalians. However, unlike the supposition that the coin's 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 inadequacy of silver extraction as a result of not using copper in these coins, existence of lead, and elemental variety especially in the sec-ond and third periods.