Dirty old money: Researchers reveal Iron Age silver forgery

"It is likely they used money that was already in the area from previous periods, to which they added the copper from the Timna area."

Silver pieces from Tel Megiddo (photo credit: CLARA AMIT ISRAELI ANTIQUITIES AUTHORITY)
Silver pieces from Tel Megiddo
Ancient counterfeiting is the subject of a joint study by the University of Haifa and the Hebrew University of Jerusalem that will be published in the upcoming issue of the Journal of Archaeological Science. The study found evidence of a severe shortage of silver in the Levant during the first Iron Age (between 1200-950 BCE), the period when the tribes of Israel settled in Canaan, which led to the creation of silver made with a high percentage of copper.
“The small percentage of silver in the pieces of silver, which were mixed with other substances such as arsenic that made them appear silver in color... reinforces the hypothesis that at least for part of the period, it was a deliberate forgery,” the researchers said.
The current study is part of the doctoral dissertation of Tzilla Eshel under the supervision of Prof. Ayelet Gilboa, both from the University of Haifa, as well as Prof. Yigal Erel and Dr. Naama Yahalom-Mack from the Hebrew University. It examines data from sites in Beit She’an, Megiddo and Ashkelon dating to that period, and posits that the silver shortage and instability could be one of the reasons for the migration of the tribes of Israel from the Haran area to Canaan.
According to the researchers, at that time no coins had yet been minted, and trading was done using silver pieces that were not uniform, so the amount of silver in each piece was important.
As part of Eshel’s doctoral dissertation and other previous studies, it has been established that silver earrings from the area from earlier periods (starting from 1900 BCE) were made of almost 100% silver, as were those from later periods. However, when the researchers examined the chemical composition of these Iron Age caches, they found that they were made of an alloy composed mainly of copper, with the copper content as high as 80% in certain pieces.
The researchers also found that substances such as arsenic were also added to these alloys, in order to give the ingot a silver color. While the researchers said there was no conclusive evidence that this was a forgery, they feel that there was a deliberate attempt to simulate the silver color of these metal pieces.
“In addition to the fact that there was a deliberate attempt to paint the metal silver, we found that in the ancient caches the percentage of copper was higher and the amounts of arsenic were very similar from piece to piece,” they wrote.
In light of the historical knowledge of the situation in the area and these new findings, the researchers estimate that the period 1200-950 BCE in the southern Levant was a time when residents of the area could not obtain genuine silver metal. But because they needed silver for trade, they created these counterfeit pieces.  
The researchers actually tried to test whether they could identify the source of the silver that was in these ingots, to gauge how small the amount of real silver actually was. A common process to do this is to perform an isotope test for lead that is in the money, a procedure that makes it possible to identify the source and the period from which it comes. Such an examination conducted by other researchers of silver production from the period led them to conclude that the source of the money is from the area of Spain.
In this study, however, the researchers found that because it is such a “dirty” alloy, the normal isotope test could not be performed. Instead, they estimate that based on a model they performed, the copper in the alloy comes from the same period from mines in the Timna area.
“It is likely that they used money that was already in the area from previous periods, to which they added the copper from the Timna area,” they said.
Eshel writes that: ”In the book of Ezekiel in Chapter 22, the prophet prophesies that he is angry with God over the children of Israel and says: ‘Son of man, the people of Israel have become dross to me; all of them are the copper, tin, iron and lead left inside a furnace.’
“The sentence itself is of course a metaphor for the relationship between God and the children of Israel,” she concludes. “But in practice, it is quite possible that it describes a reality that was familiar at the time: A silver ingot was mixed with various metals such as tin, iron and ore.”