Minecraft wiki entry for Things_not_to_do, associated text: Unlike cobblestone, stone and stone bricks cannot be used to make tools, should the need arise. In addition, having to mine stone out again after having smelted it leaves the player without cobblestone, and the player wastes any fuel used to smelt the stone unless it had been mined with a Silk Touch tool. It is always a good idea to keep a decent stock of cobblestone on hand.