The denomination (i.e., the Canadian five-cent piece) had been introduced in 1858 as a small, thin sterling silver coin, that was colloquially known as a "fish scale," not a nickel. The larger base metal version made of nickel, and called a "nickel," was introduced as a Canadian coin in 1922, originally as 99.9% nickel metal. These coins were magnetic, due to the high nickel content. Versions during World War II were minted in copper-zinc, then chrome and nickel-plated steel, and finally returned again to nickel, at the end of the war. A plated steel version was again made from 1951 to 1954 during the Korean War. Rising nickel prices eventually caused another switch to cupronickel in 1982 (an alloy similar to the US nickel), but more recently, Canadian nickels are minted in nickel-plated steel, containing a small amount of copper. Due to the aforementioned rise in nickel prices, since 1982, five-cent pieces composed of 99.9% nickel have been slowly removed from circulation to be melted by the Royal Canadian Mint. Only cupronickel and modern multi-ply plated steel five-cent pieces are considered "circulation coins". As a result, pre-1982 five cent pieces are often sought by collectors.