this mod adds a couple of ores and alloys
there's tin, copper, bronze, and steel
the main thing is that you can only make tools and armor from bronze and steel, but you can't get them in the mine. bronze is made from a mix of copper and tin, and steel is made from pieces of steel that are obtained from remelting iron, they can make armor and tools, like steel is better than diamond, but worse than niserite and bronze is a kind of substitute for iron