During colonial times, coins were composed of gold, silver and copper. The U.S. Mint produced gold coins until 1933, during the Great Depression. The silver in quarters and dimes was replaced in 1966. Today, nickels, dimes, quarters, and half-dollars are composed of copper and nickel. They have a copper core and an outer layer composed of a 75 percent copper, 25 percent nickel alloy. Pennies, once copper coins, are now composed of copper-plated zinc.