Because iron one is too hard to be crushed, the rock is milled with a drop hammer - pestle of several hammers - or a mallet while water flows over it at the same time to drive the dough obtained in a gutter. Because it is heavier than other minerals, the ore settles in the bottom of the container by sedimentation. After drying, the extracted nuggets are put in the low furnace: when it is heated, the iron absorbs the wood carbon and turns into steel. After smelting, the material is immediately hammered to be compacted into an ingot.