This week we are starting a four-part look (I, II, III, IVa, IVb, addendum) at pre-modern iron and steel production. 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.
So this first post is going to focus on mining. Next week we’ll take a look at ore processing, smelting in more detail, along with the pressing issue of fuel. The week after that we’ll look at the basic principles behind forging. And finally in the last week, we’ll ask what one might do if they wanted steel instead of iron. As with the farming posts, there are likely to be some addendum (at least one, on Wootz steel, for sure). Throughout all of this, we are going to look not only at the processes by which these objects were produced, but also the people who did that production.
As with farming, there is a regional and chronological caveat necessary here: my research into metal production (and this, even more than farming, is core to my academic interests) is focused on the Roman world or – more broadly – on the broader Mediterranean and European tradition of metal-working. There are some points where it will be necessary to note different methods or techniques in other parts of the world (early cast iron in China, for instance, or Wootz steel in India). Likewise, I will do my best to capture changes in metal-working techniques in the medieval period. What I am not going to cover in detail is modern steel and iron-working (that is, post-industrial-revolution), though I will occasionally note how it is different (the largest difference, by far, is that modern steel-making approaches the carbon problem from the opposite direction, with processes to remove carbon, instead of processes to add carbon).
I should also note that this post is going to focus on iron-working (and steel-working). Copper and bronze, the other major tool-metals, are quite different (and may get their own series at some point)!
As always, if you like what you are reading here, please share it; if you really like it, you can support me on Patreon. And if you want updates whenever a new post appears, you can click below for email updates or follow me on twitter (@BretDevereaux) for updates as to new posts as well as my occasional ancient history, foreign policy or military history musings.
Bibliography Note at the Outset: For the sake of keeping these posts readable, especially since I don’t have a footnote function here, I am not going to laboriously cite everything at each point of reference, but instead I am going to include a bibliography up-front for the entire series. For the beginner looking to get a basic handle on the pre-modern iron-production process, I think D. Sim & I. Ridge, Iron for the Eagles: The Iron Industry of Roman Britain (2002) offers one of the best whole-process overviews. On technical details of the forging process, note A.W. Bealer, The Art of Blacksmithing (1969), though much of the same may be learned by conversing with traditional blacksmiths. H. Hodges, Artifacts: An Introduction to Early Materials and Technology (1989) is more diffuse, but still has some useful information on metal production.
There is a robust if somewhat aging literature on Roman mining and metallurgy. Of particular note are (in publication order) J.F. Healy, Mining and Metallurgy in the Greek and Roman World (1978); R.F. Tylecote, The Early History of Metallurgy in Europe (1987); R. Shepherd, Ancient Mining (1993); P. Craddock, Early Metal Mining and Production (1995); V.F. Buchwald, Iron and Steel in Ancient Times (2005). Each of these volumes has their own advantages. Healy and Shepherd are more narrowly focused on Greek and Roman antiquity; Healy has the better coverage of processes, Shepherd the better catalog of known metal mining and processing sites in antiquity. Both Tylecote and Craddock have a wider chronological reach; Craddock is in some ways an update of Tylecote, but the former has a stronger focus on artifacts than the latter. Buchwald is narrowly focused on iron (the others all consider at least bronze, if not also non-tool metals) and of course, the most recent. Finding any study on the condition of medieval mine-workers was difficult (being so far out of my field), but note J.U. Nef, “Mining and Metallurgy in medieval Civilisation” in The Cambridge Economic History of Europe, volume 2: Trade and Industry in the Middle Ages, 2nd. ed. (1987): 691-761.
For the particulars of how that iron might be turned into armor, note D. Sim and J. Kaminski, Roman Imperial Armour: The Production of Early Imperial Military Armour (2012) for the Roman period and A. Williams, The Knight and the Blast Furnace: A history of the metallurgy of armour in the Middle Ages & the early modern period (2003). For metallurgy as it fits into mobilization more generally, J. Landers, The Field and the Forge: Population, Production and Power in the Pre-Industrial West (2003) is a peerless starting point.
On the value and trade in metals in the ancient world, of particular note are M. Treister, The Role of Metals in Ancient Greek History (1996) and L. Bray, “‘Horrible, Speculative, Nasty, Dangerous’: Assessing the Value of Roman Iron,” Britannia 41 (2010): 175-185. Both of these have valuable price-data from the ancient world.
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. We’ll get to the major problems with iron-working in subsequent weeks (they are in the processing, not the mining), but in brief the problems iron has is that it has a much higher melting point and that cast iron is functionally useless. But let’s get back to those sources of iron.
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.
Instead, basically all iron was smelted from iron ores which required considerable processing to produce a pure metal. There are quite a lot of ores of iron, but not all of them could be usefully processed with ancient or medieval technology. The most commonly used iron ore was hematite (Fe2O3), with goethite (HFeO2) and limonite (FeO(OH)·nH2O) close behind. Rarer, but still used was magnetite (Fe3O4) and siderite (FeCO3). All of these can occur in big rock deposits, but may also occur as ‘bog iron‘ where oxidation occurs in acidic environments (in swamps and bogs) leading to the formation of small clumps of iron-rich material. Many of these ores can be spotted visually by someone who knows what they are doing; hematite can be blackish to reddish-brown but leaves tell-tale red streaks (of rust); goethite’s black-brown color is also fairly recognizable, as is limonite with its burnt yellow-orange hue. We’ll come back to these ores a few times both this week and next, because while they can all yield iron, some of them yield that iron easier than others.
One distinction here is between bog iron and iron in ore deposits. Bog iron is formed when ground-water picks up iron from iron-ore deposits, where that iron is then oxidized under acidic conditions to form chunks of iron minerals (goethite, magnetite, hematite, etc.), typically in smallish chunks. Bog iron is much easier to smelt because it contains fewer impurities than iron ore in rock deposits, but the quantity of iron available from bog iron is relatively low (although actually renewable, unlike mines; a bog can be harvested for iron again after a few decades as the processes which produce the bog iron continue). Because of its low output, bog iron tends to be an important part of the iron supply only when production is relatively low, such as during the Pre-Roman Iron Age in Europe, or the early medieval period.
But what I want to stress here at the outset is that while the local variety of iron may vary based on conditions, iron ores are sufficiently common that prior to the industrial revolution, it wasn’t generally necessary to trade or transport them over long distances because most areas have deposits. There are some exceptions (Japan is notoriously mineral poor – my limited geological understanding is that this is common in volcanic land formations – and while it does have some iron deposits, they are few and relatively small), but for the most part, getting iron ore was not hard. As we’ll see, timber availability was actually often a more pressing limitation on iron exploitation than the ore itself, but that’s a topic for next week.
First, we have to get all of these ores out of the ground. Finding ore in the pre-modern period was generally a matter of visual prospecting, looking for ore outcrops or looking for bits of ore in stream-beds where the stream could then be followed back to the primary mineral vein. It’s also clear that superstition and divination often played a role; as late as 1556, Georgius Agricola feels the need to include dowsing in his description of ore prospecting techniques, though he has the good sense to reject it.
As with many ancient technologies, there is a triumph of practice over understanding in all of this; the workers have mastered the how but not the why. Lacking an understanding of geology, for instance, meant that pre-modern miners, if the ore vein hit a fault line (which might displace the vein, making it impossible to follow directly) had to resort to sinking shafts and exploratory mining an an effort to ‘find’ it again. In many cases ancient miners seem to have simply abandoned the works when the vein had moved only a short distance because they couldn’t manage to find it again. Likewise, there was a common belief (e.g. Plin. 34.49) that ore deposits, if just left alone for a period of years (often thirty) would replenish themselves, a belief that continues to appear in works on mining as late as the 18th century (and lest anyone be confused, they clearly believe this about underground deposits; they don’t mean bog iron). And so like many pre-modern industries, this was often a matter of knowing how without knowing why.
Once the ore was located, mining tended to follow the ore, assuming whatever shape the ore-formation was in. For ore deposits in veins, that typically means diggings shafts and galleries (or trenches, if the deposit was shallow) that follow the often irregular, curving patterns of the veins themselves. For ‘bedded‘ ore (where the ore isn’t in a vein, but instead an entire layer, typically created by erosion and sedimentation), this might mean ‘bell pitting’ where a shaft was dug down to the ore layer, which was then extracted out in a cylinder until the roof became unstable, at which point the works were back-filled or collapsed and the process begun again nearby.
All of this digging had to be done by hand, of course. Iron-age mining tools (picks, chisels, hammers) fairly strongly resemble their modern counterparts and work the same way (interestingly, in contrast to things like bronze-age picks which were bronze sheaths around a wooden core, instead of a metal pick on a wooden haft).
For rock that was too tough for simple muscle-power and iron tools to remove, the typical expedient was ‘fire-setting,’ which remained a standard technique for removing tough rocks until the introduction of explosives in the modern period. Fire-setting involves constructing a fuel-pile (typically wood) up against the exposed rock and then letting it burn (typically overnight); the heat splinters, cracks and softens the rock. The problem of course is that the fire is going to consume all of the oxygen and let out a ton of smoke, preventing work close to an active fire (or even in the mine at all while it was happening). Note that this is all about the cracking and splintering effect, along with chemical changes from roasting, not melting the rock – by the time the air-quality had improved to the point where the fire-set rock could be worked, it would be quite cool. Ancient sources regularly recommend dousing these fires with vinegar, not water, and there seems to be some evidence that this would, in fact, render the rock easier to extract afterwards.
By the beginning of the iron age in Europe (which varies by place, but tends to start between c. 1000 and c. 600 BC), the level of mining sophistication that we see in preserved mines is actually quite considerable. While Bronze Age mines tend to stay above the water-table, iron-age mines often run much deeper, which raises all sorts of exciting engineering problems in ventilation and drainage. Deep mines could be drained using simple bucket-lines, but we also see more sophisticated methods of drainage, from the Roman use of screw-pumps and water-wheels to Chinese use of chain-pumps from at least the Song Dynasty. Ventilation was also crucial to prevent the air becoming foul; ventilation shafts were often dug, with the use of either cloth fans or lit fires at the exits to force circulation. So mining could get very sophisticated when there was a reason to delve deep. Water might also be used to aid in mining, by leading water over a deposit and into a sluice box where the minerals were then separated out. This seems to have been done mostly for mining gold and tin.
But I don’t want to get too deep into this, because almost none of this fancy complexity was used in iron mining. Remember iron? This is a post about iron. As you will recall, iron’s great advantage is that iron ores are relatively abundant, which meant that it was rarely necessary or worthwhile to construct complex mining works to extract it. Only very rich ores would induce pre-modern miners into engaging in deep underground mining for iron; for the most part, it simply wasn’t worth the effort. One of these days, we might talk about the production chain for gold or silver or copper, which were worth the kind of effort to set up complex drainage and ventilation systems.
Instead, iron was generally mined in simple open-pit mines or trenches (if following a shallow vein), using a mix of fire-setting and iron hand-tools. There are some instances of more complex works chasing veins of particularly rich iron ores; my understanding is that there was Roman underground mining of iron in Noricum, for instance, after c. 15 B.C. or so. But the primary iron-mining site for Roman Italy, Elba (which has been estimated to produce a truly staggering 10,000,000 tons per year of ore for several centuries during the Republic; Diodorus (5.13.1) reports that the fires of the smelters were so continuous that the island ended up known as ‘the smokey island’ – Aethaleia – because it was always wreathed in smoke) was, as Healy notes (91) entirely opencast save for one small gallery. As far as I can tell, the bulk of pre-modern iron mining in all periods was done in open-pit (or ‘opencast’) mines. That makes simple all sorts of otherwise complicated problems with ventilation, drainage or ore extraction. Large iron mines of this sort could have several thousands of workers doing this, but smaller operations were also common; there doesn’t seem to really have been a standard size for an iron-mine.
So to recap, our iron tool begins its life as a vein or bed of iron-rich ore. Our miners, detecting this ore probably by where it outcrops to the surface, have most likely constructed an open-pit mine to extract it. Bit by bit, using shovels for the soil and then picks, hammers and chisels for the rock underneath, the non-metal-bearing rock is cleared away to expose to the ore itself. The ore is then cleared in much the same manner. Where it is stubborn, the miners set fires over the rock or against the sides of their pits to shatter the stone for easier removal. Apart from this fire-setting, all of the energy to hew our bit of hematite or limonite or what have you out of the ground is provided by human muscle. Once extracted, the ore is loaded into baskets (probably wicker-work, but the exact basket depends on where we are) and manually hauled out of the pit to the surface.
What about the fellows who did all of this work? As always, it depends a fair bit on the period and the place. Essentially the problem that miners faced was that while mining could be a complex and technical job, the vast majority of the labor involved was largely unskilled manual labor in difficult conditions. Since the technical aspects could be handled by overseers, this left the miners in a situation where their working conditions depended very heavily on the degree to which their labor was scarce.
In the ancient Mediterranean, the clear testimony of the sources is that mining was a low-status occupation, one for enslaved people, criminals and the truly desperate. Being ‘sent to the mines’ is presented, alongside being sent to work in the mills, as a standard terrible punishment for enslaved people who didn’t obey their owners and it is fairly clear in many cases that being sent to the mines was effectively a delayed death sentence. Diodorus Siculus describes mining labor in the goldmines of Egypt this way, in a passage that is fairly representative of the ancient sources on mining labor more generally (3.13.3, trans Oldfather (1935)):
For no leniency or respite of any kind is given to any man who is sick, or maimed, or aged, or in the case of a woman for her weakness, but all without exception are compelled by blows to persevere in their labours, until through ill-treatment they die in the midst of their tortures. Consequently the poor unfortunates believe, because their punishment is so excessively severe, that the future will always be more terrible than the present and therefore look forward to death as more to be desired than life.
It is clear that conditions in Greek and Roman mines were not much better. Examples of chains and fetters – and sometimes human remains still so chained – occur in numerous Greek and Roman mines. Unfortunately our sources are mostly concerned with precious metal mines and those mines also seem to have been the worst sorts of mines to work in, since the long underground shafts and galleries exposed the miners to greater dangers from bad air to mine-collapses. That said, it is hard to imagine working an open-pit iron mine by hand, while perhaps somewhat safer, was any less back-breaking, miserable toil, even if it might have been marginally safer.
Conditions were not always so bad though, particularly for free miners (being paid a wage) who tended to be treated better, especially where their labor was sorely needed. For instance, a set of rules for the Roman mines at Vipasca, Spain provided for contractors to supply various amenities, including public baths maintained year-round. The labor force at Vipasca was clearly free and these amenities seem to have been a concession to the need to make the life of the workers livable in order to get a sufficient number of them in a relatively sparsely populated part of Spain.
The conditions for miners in medieval Europe seems to have been somewhat better. We see mining communities often setting up their own institutions and occasionally even having their own guilds (for instance, there was a coal-workers guild in Liege in the 13th century) or internal regulations. These mining communities, which in large mining operations might become small towns in their own right, seem to have often had some degree of legal privileges when compared to the general rural population (though it should be noted that, as the mines were typically owned by the local lord or state, exemption from taxes was essentially illusory as the lord or king’s cut of the mine’s profits was the taxes). It does seem notable that while conditions in medieval mines were never quite so bad as those in the ancient world, the rapid expansion of mining activity beginning in the 15th century seems to have coincided with a loss of the special status and privileges of earlier medieval European miners and the status associated with the labor declined back down to effectively the bottom of the social spectrum.
(That said, it seems necessary to note that precious metal-mining done by non-free Native American laborers at the order of European colonial states appears to have been every bit as cruel and deadly as mining in the ancient world.)
Georgius Agricola, describing mining in the 16th centuries, gives a sense of the hours miners worked and the pay they received, noting that in many cases miners were forced to pull multiple consecutive 7-hour shifts just to survive, with the mine itself being worked around the clock when necessary:
Since I have mentioned the shifts, I will briefly explain how these are carried on. The twenty-four hours of a day and night are divided into three shifts, and each shift consists of seven hours. The three remaining hours are intermediate between the shifts, and form an interval during which the workmen enter and leave the mines. The first shift begins at the fourth hour in the morning and lasts till the eleventh hour; the second begins at the twelfth and is finished at the seventh; these two are day shifts in the morning and afternoon. The third is the night shift, and commences at the eighth hour in the evening and finishes at the third in the morning. The Bergmeister does not allow this third shift to be imposed upon the workmen unless necessity demands it. In that case, whether they draw water from the shafts or mine the ore, they keep their vigil by the night lamps, and to prevent themselves falling asleep from the late hours or from fatigue, they lighten their long and arduous labours by singing, which is neither wholly untrained nor unpleasing. In some places one miner is not allowed to undertake two shifts in succession, because it often happens that he either falls asleep in the mine, overcome by exhaustion from too much labour, or arrives too late for his shift, or leaves sooner than he ought. Elsewhere he is allowed to do so, because he cannot subsist on the pay of one shift, especially if provisions grow dearer. [emphasis mine]
Agricola’s mine-workers (note that the translation I linked to uses the word ‘miner’ to mean essentially ‘mine-owner’ whereas ‘workman’ is the word used when Agricola means actual mine-laborers) live in a barracks next to the shift house. While Agricola insists that mining is not so perilous as often believed, it is impossible not to note the sheer number of references to accidents which might befall workmen, from cave-ins to falling down ladders to drowning in undrained water, to death by poisonous fumes or bad air, to a note that mine workmen are peculiarly subject to disease.
One might wonder, even with amenities or small legal privileges, why anyone would sign up for this kind of work. Obviously, non-free miners sent to the mines either as enslaved or convict labor had no choice, but as noted even in the ancient world, there seem to have been a significant number of free miners as well. The supply of desperate people willing to work in such a dangerous job becomes more understandable when we think about the structure of the agricultural economy around these mines: opportunities for wage labor were few, so for individuals who found themselves without any land of their own, economic options to survive were limited. The rural or urban poor were mostly not in a position to acquire the skills necessary to work as craftsmen (such skills were generally passed down through apprenticeship systems and often restricted by professional societies like guilds or collegia). Indeed, the tendency of cities to accumulate unemployable laborers seems to have been a major motivator for many of the large-scale state building projects (like those of Pericles, or Augustus), effectively as ‘jobs programs’ at state expense; that such projects seem to have always found large and ready labor forces is telling. This inefficiency, an economy not well organized to effectively employ surplus labor, is a common feature of pre-modern economies, creating a ready supply of people desperate enough to do things like work in the mines merely to eat.
Meanwhile, mines were effectively never owned or operated by the miners themselves. While we occasionally see periods where private ownership of mines is common (there seems to have been a fair bit of this in the Roman Republic) in practice, mining seems to have been a state-dominated enterprise in both the ancient and medieval world. Typically, the ruler (king, lord, emperor, etc) owned the mine itself and appointed an administrator to oversee it for him. The Athenian state seems to have owned and controlled the silver mines at Laurium; oversight, operations and contracting were supervised by a board of poletai appointed from the citizenry. Mines in the Hellenistic kingdoms seem to have generally been the property of the king personally and mining in pre-Roman Gaul was apparently owned by the Gallic nobility. Roman mines during the imperial period were almost all part of the fiscus (the personal property of the emperor which functioned as a sort of second treasury). Actual on-the-ground administration of the mines varied, sometimes run by conductores or procuratores appointed by the state, sometimes contracted out to private government contractors, the publicani (this more commonly in the Republic).
All Dressed Up
Once our ore reaches the surface (or is removed from its open pit) it is not immediately ready for smelting, but has to go through a series of preparatory steps collectively referred to as ‘dressing’ to get the ore ready for its date with the smelter (note: it seems to me that roasting is sometimes included in ore dressing and sometimes not; we’ll talk about it next week).
Ore removed from the mine would need to be crushed, with the larger stones pulled out of the mines smashed with heavy hammers (against a rock surface) in order to break them down to a manageable size. The exact size of the ore chunks desired varies based on the metal one is seeking and the quality of the local ore. Ores of precious metals, it seems, were often ground down to powder, but for iron ore it seems like somewhat larger chunks were acceptable. I’ve seen modern experiments with bloomeries (which we’ll get to next week) getting pretty good results from ore chunks about half the size of a fist. Interestingly, Craddock notes that ore-crushing activity at mines was sufficiently intense that archaeologists can spot the tell-tale depressions where the rock surface that provided the ‘floor’ against which the ore was crushed have been worn by repeated use.
Ore might also be washed, that is passed through water to liberate and wash away any lighter waste material. Washing is attested in the ancient world for gold and silver ores (and by Georgius Agricola for the medieval period for the same), but might be used for other ores depending on the country rock to wash away impurities. The simple method of this, sometimes called jigging, consisted of putting the ore in a sieve and shaking it while water passed through, although more complex sluicing systems are known, for instance at the Athenian silver mines at Laurium (note esp. Healy, 144-8 for diagrams); the sluices for washing are sometimes called buddles. Throughout these processes, the ore would also probably be hand-sorted in an effort to separate high-grade ore from low-grade ore.
It’s clear that this mechanical ore preparation was much more intensive for higher-value metals where making sure to be as efficient as possible was a significant concern; gold and silver ores might be crushed, sorted, washed and rewashed before being ground into a powder for the final smelting process. Craddock presents a postulated processing set for copper ore for the Bronze Age Timna mines that goes through a primary crushing, hand-sorted division into three grades, secondary crushing, grinding, a winnowing step for the low-grade ore (either air winnowing or washing) before being blended into the final smelter ‘charge.’
As far as I can tell, such extensive processing for iron was much less common; in many cases it seems it is hard to be certain because the sources remain so focused on precious metal mining and the later stages of iron-working. Diodorus describes the iron ore on Elba as merely being crushed, roasted and then bloomed (5.13.1) but the description is so brief it is possible that he is leaving out steps (but also, Elba’s iron ore was sufficiently rich that further processing may not have been necessary). In many cases, iron was probably just crushed, sorted and then moved straight to roasting, which we will cover next week.
Conclusion: From Large Rock to Slightly Smaller Rock
I realize the reader may be a bit disappointed that we have spent all of this time to get our iron ore from being in the ground in a very large rock, to hewn out of the ground into a slightly smaller, but still large rock, to smashed (and possibly washed) into a small rock, which still doesn’t get us very close to any kind of metal. One assumes ancient miners were also disappointed at just how much effort it took to force the earth to give up its bounty.
And we are not, in most cases, about the leave the mining site either. Iron ore, even crushed, is terribly heavy and bulk and as we’ll see next week, the ratio of metal to useless rock really favors useless rock. Consequently, if you could do the entire smelting process at the mine, you did, rather than transport so much of that useless rock far away only to have it turned into slag there.
But there’s a larger shift that’s going to happen in our processing next week, because we’re going to begin applying heat. And that means we’re going to need fuel. Lots of fuel, it turns out. Lots and lots of fuel. So, next week: roasting and smelting. We’re going to let a thousand iron flowers bloom (a pun so bad it could make you, like Diodorus’ miners, wish for death).