Billon

ビロン　—　Making

A low-fineness alloy of silver and copper. Used for provincial silver coins and medieval small-denomination coins.

Billon denier tournois (debased issue)1295–1303 Gold maravedí of Alfonso VIII1174–1217 (held to be struck at Toledo)

A low-fineness alloy of silver and copper. In Alexandria under Roman rule, billon tetradrachms with low silver content were struck for about 300 years. In medieval Spain, the maravedí, which began as a gold coin, was debased to billon, and after losing its physical form, it survived as a unit of account until the 19th century.

⚠ While the name remained that of a silver coin, the content increasingly approached that of copper. It is the alloy found at the final stage of debasement.