chromium

Let's face it. Gold is one of the LEAST used variant of metal than wood! I think a new metal should be added in for tools and armor. No im not saying get rid of gold because it still has SOME uses but something else that is better than gold for tools and armor would be better suited in the line up. 
The spot to replace gold for tools and armor should go to...

chromium
Not only is this metal better and would probably last longer than gold It's common too! it could also be slightly better than iron but i dont know the metal too much myself.