"Potin (also known as billon) is a base metal silver-like alloy used in coins. It is typically a mixture of copper, tin and lead (in varying ...
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proportions) and it is debated whether any actual silver needs to be present. While the term billon is more commonly applied to ancient Roman coinage, potin is usually used for Greek or Celtic coinage." - (en.wikipedia.org 15.12.2019)
