I am not really into exotic rules for minted coins. Gold is gold and silver is silver. Copper and iron,.. are worth less. A ‘piece’ is set to be a standard weight and encumbrance is based on that. Bringing in a whole side story of mints and bankers should be just a side story. Enough restrictions are put on availability of goods in the ACKs rule set, not to be further complicated by whether or not i can buy +1 nipple rings with Canadian silver.