"Trade silver" was a term used to describe small pieces of jewelry brought by the Europeans to trade for furs. The Native Americans did not have the ability to do this kind of intricate metal work, and so it was valuable to them. Most of the goods traded were indeed silver, although metals such as brass were also used. The Spanish flooded the market with silver when they discovered it in South America. Trade silver was probably one of the first items used in global commerce. Welcome to the global economy!