Having a currency defined in terms of two different metals is called bimetallism. Such a system may experience instability as the price of gold and silver on the world market changes, and this took place in the first decades after 1792, as the relative values of gold and silver in Europe changed. At that time, gold or silver U.S. coins were rarely seen in the nation, as they were heavily exported because of such shifts—most pieces in circulation were foreign in origin.[1][2]