2019-6-26 · A nickel, in American usage, is a five-cent coin struck by the United States Mint. Composed of 75% copper and 25% nickel, the piece has been issued since 1866. Its diameter is .835 inches (21.21 mm) and its thickness is .077 inches (1.95 mm). Due to inflation, the purchasing power of the nickel continues to drop and currently the coin ...