All circulating coins have a common side showing the denomination or value, and a map in the background.
The pieces remain the only US circulating coins with recessed designs.
The Chinese reckoned in weights of silver, which did not necessarily correspond to circulating coins.
Detractors comment that circulating coins are intended to showcase the culture of the country which issues them, and therefore have historical interest.
As Canada also has coloured circulating coins, Australia is now the second country to do so.
Its exchange for circulating coins was removed on 1 October 2011.
Due to the lack of known examples and documentary evidence, these coins are thought to be trials rather than circulating coins.
During this same period, silver gradually ceased to be used in circulating coins.
The association has circulated valuable coins during previous conventions, but none has ever been turned in.
Circulating coins, however, were not affected by this change.