The dollar coin is a United States coin worth one United States dollar. It is the second largest American coin currently minted in terms of physical size, with a diameter of 1.043 inches (26.5 mm) and a thickness of .079 inches (2 mm), coming second to the half dollar. Dollar coins have been minted in the United States in gold, silver, and base metal versions. The term silver dollar is often used for any large white metal coin issued by the United States with a face value of one dollar, whether or not it contains some of that metal. The Sacagawea and Presidential dollars are sometimes referred to as golden dollars. Silver dollars, the first dollar coin issue, were minted beginning in 1794. Gold dollars and gold-colored dollars have also been produced by the United States.