Definition: A clad coin is one that has multiple layers of metal in it; most current U.S. clad coins consist of an inner core of copper, with outer layers of a silver-colored nickel-copper alloy. Examples of this type of clad coin are the U.S. Dime, Quarter, and Half Dollar.
The golden dollar coins, including the Sacagawea Dollar and the Presidential Dollars, are also clad. They have a copper core with clad layers made from a zinc, manganese, and nickel combination.
The golden dollar coins, including the Sacagawea Dollar and the Presidential Dollars, are also clad. They have a copper core with clad layers made from a zinc, manganese, and nickel combination.
Examples:
On most U.S. clad coins, if you look at the edge of the coin, you can see the copper core sandwiched between the outer layers of metal.

