Iron ore Official Life is Feudal Wiki
You may turn it into Lumps of Iron, Iron Bars, and Iron Ingots. A conversion chart for the materials need to the items will be below. You can save durability on your furnace by always melting ore into ingots and afterwards reheat the ingots to 1500 degrees and smelt them into bars or lumps. it produces the same amout of materials with only 4 uses of the furnace instead of 80 when making lumps for example.