DeviantArt by Raudan Valmistus, where you'll need to go to really see this image at the right size. The post follows his project from mining the local iron ore from the bottom of a lake, through refining that ore, and finally to a steel knife. Steel? He writes:
Analysis was made for another blade I made at same time, from same iron. Its carbon content is about 0,531%The American Iron and Steel Institute defines carbon steel as having a carbon content of 0.12 to 2.0 %. The carbon in this process seems to be absorbed from the charcoal used to work the iron. It's one of the most profound and serendipitous "accidents" of the way the universe is put together that the way to make elemental iron more useful is add the element most likely to be added by the simplest ways of melting it: a wood or charcoal fire. It guarantees that steel, arguably the backbone of civilization, would be discovered as soon as man learned how to control fire, blow air across it to make it hotter and allow us to melt elemental iron.
But that sounds like the universe was intelligently designed and didn't just happen from an un-namable number of random interactions, and we know intelligent people can't hold that idea, right?