In heraldry, copper is the tincture of metallic copper. Copper has been introduced in Canadian heraldry. It is considered a metal along with Argent (silver) and Or (gold) and should be depicted as bright, new copper metal.
While not commonly used, it features prominently in the arms of the City of Whitehorse, Yukon.
References
Copper (heraldry) Wikipedia(Text) CC BY-SA