Cupronickel
Cupronickel is an alloy. It is made of copper and nickel. It is used in nickels, the US coins. It does not corrode. It is silvery in color. It has 75% copper and 25% nickel.
Cupronickel Media
Two stacks of Half dollars. The coins in the stack on the right are composed of copper with cupronickel cladding, and can be distinguished from the silver half dollars on the left by their visible copper cores.
Five Indian rupees, commemorating ILO
A Cupro-nickel coin of king Euthydemus II, c. 185–180 BC. Notice the coin looks more corroded than the usual silver coins.