was copper ever used as a currency?
History of copper currency in Sweden. An 8 daler piece of plate money (plÃ¥tmynt) in the British Museum. The Swedish Empire had the greatest and most numerous copper mines in Europe as it entered into its pre-eminence in the early 17th century as an emerging Great Power.
Sweden's large army of the time were paid entirely in copper currency, further issued in large numbers by Gustavus II to finance his war against Ferdinand II of Germany.