Bi-metallic coin dated 2006 (minted at Noida). Since 1996, Canada has also produced bi-metallic $2 coins (nicknamed "toonies"). Great Britain has issued a bi-metallic 2-pound coin since 1997; and Singapore has issued a bi-metallic 1-dollar coin since 2013. The first ever tri-metallic circulating coins were 20-francs coins introduced in France and Monaco in 1992. These were similar to the corresponding bi-metallic 10-francs coins, but had two rings instead of one. As well as circulating coins, where they are generally restricted to high-denomination coins, bi-metallic coins are often used in commemorative issues, often made of precious metals. For example, the only bi-metallic coin
Dollar coin (United States) was the smallest denomination of gold currency ever produced by the United States federal government. When the U.S. system of coinage was originally designed there had been no plans for a gold dollar coin, but in the late 1840s, two gold rushes later, Congress was looking to expand the use of gold in the country’s currency. The gold dollar was authorized by the Act of March 3, 1849, and the Liberty Head type began circulating soon afterward. Because of the high value of gold, the gold dollar is the smallest coin in the history of U.S. coinage. The trade dollar