The copper pickaxe can mine redstone and gold ores.

The Stone Pickaxe can only mine coal, iron, copper, and lapis lazuli, while the Iron Pickaxe can mine gold, redstone, diamond, and emerald. Now, the Copper Pickaxe may be able to mine redstone and gold ore, as gold is a very soft mineral, and redstone ore may be a brittle stone similar to lapis lazuli, but slightly less fragile.