Copper and Silver could work very well together as money in an economic collapse. I don't think just silver or gold will be used in a situation as that. I think Gold, silver and copper will be used together. Silver bullion and copper bullion I believe would be used for common transactions. Both silver and copper are useful as trade units if pressed into coin form. If we entered into a hyperinflationary enviroment the countries that hold dollar reserves would be looking for something to trade the dollar for and I believe it will be copper, oil etc. Copper is priced in dollars so as our dollar is debased the price of copper will rise as well. A dollar collapse would cause prices of all commodities to sky rocket. Food riots, hoarding etc. Preppers should prepare for every scenario and copper bullion can't hurt.