what karat of gold is in coins
Minted in 22-karat gold  Using the durable gold standard established for gold circulating coinage more than 300 years ago, each Gold Eagle coin is minted in 91.67% fine gold alloyed with a small amount of silver and copper added to harden and protect it against damage. Pure, 24-karat gold is actually quite soft. Adding alloy to pure gold makes it many times more durable than gold itself. Each Gold Eagle coin contains its specified weight (one-ounce, half-ounce, quarter-ounce, or tenth-ounce) in pure 24-karat gold. The alloy weight is extra. A one-ounce American Gold Eagle, for example, actually weighs 1.0909 troy ounces.