You are now able to transform other metals into copper nuggets.
The first step is to throw down any Metal you have excess of into the Crucible, then follow with one food item. Then press the right mouse button (holding a wand) aimed directly at the crucible. Instant Copper Nuggets.
"Having mastered the transformation of base metals into gold, the next step would be to transform any and all metals into copper. You are now able to transform other metals into copper nuggets."
Research available after Basic Transmutation.