Gold had always been valuable because it is so rare. For thousands of years it has been used as money. Today we take money (coins and dollar bills) for granted. Until the 1930s, the United States was on the gold standard which meant that for every one dollar bill there was one dollar’s worth of gold in the U.S. Mint. A $20 gold coin could be melted and sold for $20. That is not true today as mass-produced coins are made of copper, nickel, and zinc.