One hears about the iron age and the bronze age—eras in which people discovered metallurgy. But how did that happen? Was it like:
1. Look at rock
2. See shiny
3. Try to melt the shiny out of the rock
4. Profit?
Explain it to me!
In: 1643
It’s more of a natural evolution than I think you realize. Several “technology trees” lead to metal refining.
1. Need place to sleep, make little fort from branches and mud
2. Notice after a few days mud kinda dries out and gets hard
3. Try making little bricks and cups and and figurines and stuff, dry them out in the sun. Sorta works
4. Realize some dirts work better than others, figure out clay is great for this kind of thing
5. Figure out you can speed up the process by drying them near the fire
6. Figure out placing directly in the fire actually “fires” them, makes them really strong and hold water
7. Try placing other materials in fire to see what happens, notice some kinds of dirt make little shiny metal deposits at the bottom, collect lots and make the biggest glob you can
At the same time
1. Need food. Animals are hard to catch
2. Throwing rocks kinda works, but it’s hard to throw far enough
3. Throwing sticks kinda works, but they don’t do as much harm
4. Sharpen a big stick, Spear!
5. Attach a sharp rock or obsidian, Better Spear!
6. But the rocks are heavy, wood gets dull, and obsidian breaks to easily.
New resource, and an old problem. Just took one of the millions of people around to try to use the metal for a knife/spear, and the rest is history. Humans are naturally curious and whoever managed to make the first metal device would have had a huge leg up and their tribe would have refined the practice over a few decades. They would have been so successful that there would have been strong motivation to experiment more with the new tech which would have lead to some basic alloys, entering the bronze age.
We don’t really know for sure, because people really didn’t (or, probably, couldn’t) write things down back then.
What likely happened is that somebody would build a fire pit using rocks with copper or tin in them, and when they built a big fire, the copper and tin melted out of the rocks. People might then have checked out the metal and found that it was nice for things like jewelry, but not really hard enough for anything else.
Later, somebody might have used both kinds of rocks, and noticed that the metals combined to make something (bronze) that was hard enough to make tools, and that those tools were easier to make (and better) than most stone tools. That’s when the Bronze Age started, because people who had bronze tools were much better off than people who did not.
It was only a shot time (in terms of history) before somebody discovered how to work iron, which requires much hotter fires, and has to be worked hot instead of cold, like copper and tin.
There’s a step before the time you’ve imagined. There’s places where the metals one can find are so naturally pure that no metallurgy is required. For example, there’s a place on Lake Huron where the copper is pure enough that you can work it without any complex extraction.
It seems to me that step would be first. Then, once demand for metals spreads to where very pure raw materials are in short supply, that’s when you’d start experimenting with ways to make use of progressively inferior ore through more and more sophisticated refinement. But you’d start with the only slightly defective ore so you’d only need incremental advances in your refinement technology.
The podcast Interesting Things Explained Well did a piece on this:
All the easy to find copper nuggets that were on or near the surface were scooped up during the bronze age.
So, we have to use our imagination to speculate how copper nuggets got melted in a campfire.
Copper is shiney when rubbed and its eye-catching. It’s easy to see how it could have been used as a decoration at first.
If you hammer copper, it becomes harder at the place you hammer it, so it’s easy to speculate that working copper for a decoration would provide the “a-ha” moment when you could make a dagger or axe-head out of hammered copper, instead of stone.
Stone implements had to be made every time, and copper could be melted and re-cast into a shape in a sand mould, over and over.
It may have been a minor benefit over stone tools, but it was “better enough”, and I’m sure both materials lived side-by-side for quite a while.
There’s a long story as to the likely start to adding 15% tin to make bronze. That material has all the benefits of casting copper into sand-moulds, but it is much harder.
If you watch the Primitive Technology channel on youtube, a lot of videos show how firing different kinds of pottery and dirts produced small iron prills. It probably happened in a similar fashion over thousands of years.
I’m no expert, but I’m into this topic. So keep in mind, I’m not very well-sourced in my statements, just giving a general accumulation of knowledge that may or may not be entirely accurate.
First thing to know is, mankind has pretty much always been messing around with rocks. We have records of alchemy being practiced in ancient Greece, China, India, and Egypt, where they tinkered with different plants, minerals, and other materials in all sorts of ways. Some of the records we’ve found suggest that cultures have been doing this as far back as 10,000 BCE, with the implication that the practice went back even earlier than that, and we just don’t have the written records that we can read to confirm it. At some point, as has been said, we’re pretty confident that we started messing with rocks before we figured out writing. So it’s pretty hard to know exactly when it started.
But before we got to metals, we were making tools out of stone. We figured out that, while stones are really hard, they can be broken down. In some areas, people ground the stones against each other, filing away bits from the outer surface of both rocks, until they formed a rough shape that could be used. But the lucky places had minerals like flint and obsidian: those could be broken, chipping away big shards from the rocks. This is good for tools, because it could create really sharp edges that were awesome at cutting. And with some practice, you could control the angle that you broke bits off from, and shape the flint into specific tools.
Our first records of metallurgy (that is, extracting and shaping metal from rocks) go back to the 9th millenia BCE in the general area of the Middle East. We’ve found shaped metal objects, primarily tools, that we dated to get that origin time. Probably the first metal to be worked in this way was lead, with copper, silver, gold, tin, and eventually iron following behind.
One of the processes used in metallurgy is smelting, or melting the rocks until the metals can be separated from the rest of the stone they’re found in. This was likely figured out by accident, because lead and tin actually melt at temperatures that could be reached by a regular campfire. We figured out that, if we separate the metals from the rocks and throw the rocks away, the metals left behind are much stronger and easier to work with. From there we figured out casting (melting the metal, and pouring it into a shaped container, so that the metal cools into that shape), and forging (shaping the metal with tools, often while it’s hot and more flexible).
Lead and tin are dense, but not very hard (lead being more so). So they weren’t very good as weapon or tool materials. But lead bullets, which could be fired from slings, have been found. Metals like silver, gold, and tin, being relatively soft, were often used for ornamental items, like jewelry, cups, and other objects that weren’t expected to take a lot of force in their use.
Copper was slightly harder to work out, because it melts at a higher temperature than those metals. The current theories are that ancient peoples used something like a pottery kiln, which was also in use around the time, and which could produce hotter temperatures. But before we figured that out, we were already working copper cold (that is, just beating it into shape with no heat added). Because copper is pretty soft, as far as metals go, it can be worked in that way. But despite being that malleable, it can still be worked into weapons and tools with sharp edges. Thus, we got copper weapons that worked better than stone ones. And it was such a big deal, we named a whole age after it.
Bronze was the next big development, around 4,200 BCE. Someone combined tin (or arsenic) and copper (in what might have been a chocolate/peanut butter kind of accident), and discovered alloys: combinations of minerals and metals. The resulting alloy, bronze, was still workable with the technology mankind had figured out at the time, but when cooled it was much harder than copper. So we turned it into the main material for weapons, armor, and tools. And it was such a big deal, we named a whole age after it.
Then there was iron. Iron is a lot harder than any of those metals, and it needed to be heated to even higher temperatures to work with, so it took longer for us to get to that. But we have examples of worked iron from as far back as Ancient Egypt. The theory was that, instead of getting impure iron from the ground, the earliest iron items we found were made from meteoric iron: large chunks of relatively pure iron that came from space. Meteors were also easy to reach, since they land on the Earth’s surface, compared to digging large veins of iron from the ground. But because there was only so much workable iron available, it wasn’t put into common use by anybody yet.
The process for smelting iron ores was eventually figured out around 1,200 BCE. It’s credited to the Hittites of the Middle East, but was likely figured out by other peoples separately as well. Things like charcoal (which reached higher temperatures than regular wood), and bellows (which blew air into the fire and made it burn hotter for a time) were used to help this process. The process involved constructing bigger and badder furnaces, such as bloomeries, which created controlled temperatures that could separate the iron from most of the rock, but wasn’t hot enough to actually melt the iron. The iron “bloom” then had to be reheated and folded over and over, to separate the slag and impurities from the metal.
But true iron-working was figured out in the 5th century BCE in the area of China. They built furnaces that were finally hot enough to melt iron, and thus the metal could be cast and worked. The resulting metal was *pig iron*, which had a lot of carbon in it, and other impurities like silica. While it was hard, it was also quite brittle. Much later, in the 13th Century CE, people figured out processes to refine the iron, melting it back down again in a process designed to oxidize some of the carbon and impurities, and give us an iron that’s stronger and easier to work with. We finally had iron that we could work reliably. And it was such a big deal, we named a whole age after it.
Maybe not a full answer for you, but I think good supporting information. There’s a YouTube channel “Primitive Technology” where he genuinely refines his own low quality iron using only mud and home built (mud built) techniques. Turn on captions for more details or enjoy the wild soundtrack for what it is. Excellent channel, and really informative about what a single guy can do in a plot of land without modern materials.
Bc if you give men fire, the first thing they will do is try to burn everything they can find.
I have no sources on this.
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