As with our series on farming, we are going to follow the train of iron production from the mine to a finished object, be that a tool, a piece of armor, a simple nail, a weapon or some other object. And I want to stress that broad framing: iron was made into more things than just swords (although swords are cool). If you are here wondering how you go from iron-bearing rocks to a sword, these posts will tell you, but they will equally get you from those same rocks to a nail, or a workman’s hammer, or a sawblade, or a pot, or a decorative iron spiral, or a belt-buckle, or any other of a multitude of things that might be produced in iron.
Iron production is a unique topic in one key way. If the problem with farmers is that the popular understanding of the past (either historical or fantastical) renders them effectively invisible – as indeed, it tends to render most ancient forms of production invisible – iron-working is tremendously visible, but in a series of motifs that are almost completely wrong. Iron is treated as rare when it is common, melted in societies that almost certainly lack the furnaces to do so; swords are cast when they should be forged, quenched in ways that would ruin them and the work of the iron-worker is represented as a solitary activity when every stage of iron-working, when done at any kind of scale, was a team job (many modern traditional blacksmiths work alone, often as a hobby; ancient smiths generally did not). The popular depiction is so consistently wrong that it doesn’t really even provide a firm basis for correction. We are going to have to start over, from the beginning.
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In most video games, if you are looking to produce some iron things, the first problem you invariably have is finding some iron ores. Often iron is some sort of semi-rare strategic resource available in only certain parts of the map, something that factions might fight over. Actually finding some iron might be a serious problem.
Well, I have good news for historical you as compared to video game you: iron is the fourth most common element in earth’s crust, making up around 5% of the total mass of the part of the earth we can actually mine. Modern industry produces – and I mean this very literally – a billion tons (and change) of iron per year. Iron is about the exact opposite of rare; almost all of the major ores of iron are dirt common. And that’s the point.
One of the reasons that the change from using bronze (or copper) as tool metals to using iron was so important historically is that iron is just so damn abundant. Of course iron can be used to make better tools and weapons as well, but only with proper treatment: initially, the advantage in iron was that it was cheap. Now, as we’ll see, while the abundance of iron makes it cheap, the difficulty in working it poses technological problems; that’s why the far rarer and also generally inferior (to proper, work-hardened, heat-treated iron or steel; bronze will often exceed the performance of unalloyed iron) copper and bronze were used first: harder to find, easier to work. […]
Very small amounts of iron occur on earth as pure “native” metal; the term for this, “meteoric iron” is an accurate description of where it comes from (there is also one known deposit of native “telluric iron“); in practice, the sum total of these iron sources is effectively a rounding error on the amount of iron an iron-age society is going to need and so “pure” iron may be disregarded as a meaningful source of iron.
Bret Devereaux, “Iron, How Did They Make It? Part I, Mining”, A Collection of Unmitigated Pedantry, 2020-09-18.
