What is a cupronickel coin?

A cupronickel coin is a coin that is made of an alloy of copper and nickel. Current US dimes, quarters and half dollars have an outer cladding of cupronickel, while 5-cent pieces are solid cupronickel. Many British and Australian Coins are also struck in cupronickel.

A blend of 75% copper/25% nickel is frequently used for coins because its color resembles silver while the high copper content allows it to be easily struck in coin presses. Other percentages are sometimes used; for example British 20p coins are made in an 84/16 ratio of copper to nickel.