Copper is unique chemical element.
Steel. I think. The can be made of steel, aluminum, or copper.
A 10p coin in the UK is made of a combination of metals, primarily copper-plated steel. It consists of 75% copper and 25% nickel. The outer layer is made of copper and the inner core is made of steel.
Because
The Iraqi coins made for general use since 1960 are made of nickel, copper-nickel, stainless steel, copper plated steel and nickel plated steel.
lead, copper, steel
Irish (Eire) "copper" decimal coins issued from 1971 to 1988 were made from bronze consisting of about 97% copper, the remainder being tin and zinc. Irish (Eire) "copper" decimal coins issued from 1988 to 2001 were made from copper plated steel.
Copper is a better conductor of heat than steel.
American nickels are made of 75% copper and 25% nickel Canadian nickels used to be pure nickel but are now made out of steel.
A Mike is made of steel. A Steve, however, is made of copper.
Copper plates on a steel armature structure.
Steel , Brass, Bronze, Copper,
copper, steel and glass