The history of coins dates back to the first millennium BCE, with notable examples including the Lydian Lion coins, Persian daric and siglos, Tong Bei, the dirham, and gold dinar. Coins are a major source of historical information and provide insight into the kingdom, language, administration, religion, economic conditions, and the ruler who minted the coins. The process of making
coins involved hitting a hammer over an anvil, with the Chinese producing primarily cast coinage, which spread to Southeast Asia and Japan. 
In 2016, archeologists discovered a small golden bead, the oldest processed gold artifact, which provides evidence that humans had metallurgical knowledge for thousands of years before striking coins. The question of whether the electrum used in early coins was naturally occurring or produced specifically for striking coins is still debated. However, in their book King Croesus’ Gold, Andrew Ramage and Paul Craddock argue that the discovery of the process of refining gold and silver alloys into pure metals before the first coins were struck refutes the assumption that natural alloys played a role in the origins of coinage. 
To determine whether the electrum used in a particular coin is naturally occurring or not, scientists use the technique of Prompt-Gamma Neutron Activation Analysis, a non-destructive method that measures the exact composition of an electrum coin. A French survey of electrum coins excavated at the mint at Sardis has led numismatists to conclude that all electrum coins were produced from non-natural alloys. However, it is unknown whether silver and copper were added to naturally occurring electrum or to previously processed gold. 
E.S.G. Robinson published a piece in the British Museum Quarterly in 1936 detailing two small gifts of electrum coins of Cyzicus, Phocaea, and Mytilene. Robinson discussed the varying percentages of gold and silver in the base alloys used to strike the coins, which provides further evidence that electrum was not naturally occurring. In conclusion, while there is still much debate on the origin of electrum used in early coins, the use of non-destructive techniques and further research may provide more insights into the history of coinage.
Source: archeologynews.com
