Coinage metals

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Coins are made from one or more coinage metals.

Many coinage metals are from Group 11 of the Periodic table, however there are some exceptions. Precious metals are used in bullion coins and some collectable coins. Coins not intended for circulation or for intrinsic value, have also been made experimentally using an even larger variety of metals, in technical and artistic experiments.

Coins that are intended for circulation have some special requirements based on the conditions they will encounter. For example, a coin may be in circulation for up to 30 years, and so must have excellent wear resistance and anti-corrosion properties. Achieving this goal necessitates the use of base metal alloys.

A common alloy for everyday coinage is Cupro-Nickel (also cupronickel), with varying proportions of copper and nickel. Cupronickel has a silver colour, is hard wearing and has excellent striking properties, essential for the design of the coin to be pressed accurately and quickly during manufacture.

When minting coins, especially low denomination coins, there is a risk that the value of metal within a coin is greater than the face value. This leads to the possibility of smelters taking coins and melting them down for the scrap value of the metal. Pre-1992 British pennies were made of 97% copper, as of 2008, based on the price of copper, the value of a penny from this period is 1.5 pence. Modern pennies are now made of copper plated steel.