Introduction
The reason why, after a century, Keynes’s question has not been answered satisfactorily – and the same applies to the related question whether base metals also ran short – is probably quite simple: we don’t have enough evidence, and without some kind of archaeological miracle we shall never have enough.
But the recent accumulation of relevant archaeological and scientific studies, together with sharp disagreements among historians, implies that a fresh overview may be useful. All the more so now that sustainability is more and more under discussion. But this can be no more than an overview: the subject is too complex to be covered thoroughly in an article or two. Simply to assess, for example, the historical significance of lead isotope analysis, with its potential for identifying the sources of metals, is a considerable task.Footnote 2
Places mentioned in the text. (Cartography by Gabriel Moss.)
Fig. 1. Long description
The map displays numerous ancient sites and locations marked with numbers. Key regions include the Atlantic Ocean, North Sea, Mediterranean Sea, Black Sea, and major rivers such as the Rhine, Danube, Tigris, and Euphrates. The map highlights specific locations like Jurassic Ridge, Dolaucothi, The Mendips, Camulodunum, The Weald, Cologne, Melle, Oulches, Alesia, Blessey, Lercoul, Les Martys, La Molina, Vipasca, Munigua, Vipasc, Riotinto, Elba, Rome, Pompeii, Syracuse, Carthage, Aquileia, Emona, Hüttenberg, Milan, Ravenna, Sarajevo, Crveni Potok, Stojnik, Viminacium, Kraku lu Jordan, Ratiaria, Rosia Montană, Ulpiana, Abritus, Adrianople, Byzantium, Athens, Sardis, Aphrodisias, Yassiada, Sagalassos, Anemurium, Caesarea, Bolkardağ, Antioch, Limni, Kourion, Edessa, Alexandria, Wadi Faynan, Dura Europos, and Ctesiphon. The map also includes regions such as Raetia, Noricum, Pannonia, Dalmatia, Dacia, Moesia, Thrace, Lydia, Pontus, and Cilicia.
Prior to the European expansion that began in the 15th c., there were two main chapters in the history (as distinct from the prehistory) of metal exploitation in the European and Mediterranean worlds, a Graeco-Punic-Roman chapter and an Islamic/medieval chapter. These two chapters are intimately connected to each other – which is itself a serious challenge. We cannot expect to reach convincing conclusions about the late-Roman world unless we take some heed of later conditions and conditions on the other side of the frontiers.
“Later conditions” offer in fact a crucial clue: the reason why medieval peoples were able in a number of cases to make use of metal ores that had been abandoned by the Romans/Byzantines was not – or at any rate not principally – that their technology had improved or that they were better supplied with labor but that woodlands and forests had recovered from the Roman/Byzantine onslaught.Footnote 3 This was an “organic” economy in which the enormous fuel demands of metallurgical production eventually tended to outstrip the rational timber production that was one of the most impressive aspects of the high-imperial Roman economy.Footnote 4
Gold, silver, iron, copper, lead, tin, and also (though not in an isolated form) zinc and mercury, these are our subject.Footnote 5 The chief alloys in question were bronze (copper and tin), brass (copper and zinc), billon (copper with a small amount of silver), and pewter (tin and lead), all of which could in practice contain other elements.Footnote 6
The various properties of these substances do not need to be described here, but it is at least worth noting that bronze is harder and more durable than copper: hence the considerable importance of tin in everyday life. Harder still are iron and steel (it is now agreed that Romans sometimes did manage to produce steel). It was of course iron that was really indispensable in Roman warfare.
The high Roman Empire was in fact a vast, sometimes profligate, consumer of metals – that is beyond dispute.Footnote 7 Any attempt to quantify such consumption with anything remotely like precision is probably futile, but we have some solid and striking facts. Some 350,000 high-imperial soldiers were partly paid in coins and were reasonably well supplied not only with weapons and armor, but with all the equipment that went with Roman encampments and with military transport and engineering. Estimates of the quantity of iron required by a high-imperial legion have varied widely; 300 tons may be too high an estimate, but not by much.Footnote 8 The most famous single exhibit is the deposit of iron nails from Inchtuthil in Perthshire: roughly one million iron nails, weighing nearly 10 tons, buried when the Roman army retreated from the site in 86 or 87, a deposit left behind as if it were of scant value.Footnote 9
As for civilian life, some of the famous buildings in the capital are known to have required impressive quantities of metal artifacts.Footnote 10 But it is the material from Pompeii and Herculaneum – a sort of cross-section of Italian urban existence at the height of the Roman EmpireFootnote 11 – that makes the most vivid impression: the people of the Vesuvian towns were surrounded by metals. They possessed farm implements and craftsmen’s tools, fittings for furniture and vehicles and harnesses, jewellery and ornaments, mirrors and other toiletries, statues, medical instruments, locks, nails, water pipes, assorted architectural features, and of course great numbers of coins. The city block at Pompeii that includes the famous House of the Menander, which was excavated in the 1920s and 30s, yielded 2,416 metal or partly metal objects.Footnote 12 These towns were simply rife with metal artifacts, made of all the major metals.Footnote 13
Even in the high Empire, few provincial cities can perhaps have been quite as well provided for, but deeply provincial non-elite texts, such as the synoptic gospels, confirm up to a point the pervasiveness of metal.Footnote 14 A wealth of archaeological evidence from the Roman provinces points in the same direction, showing not that metal artifacts were as commonplace as they are in rich modern countries but that they were part of the daily lives of very large numbers of ordinary people as well as of the well-to-do. Many a provincial museum offers support: take Sarajevo, for instance, where the iron finds from Bosnia and Herzegovina (in Roman terms, sections of Dalmatia and Pannonia) have been efficiently published (Fig. 1).Footnote 15 Or (mainly civilian) Camulodunum (Colchester): in the database of the Colchester museum there are about 6,000 Roman metal objects (not counting coins).Footnote 16 At the other end of the Empire, in Egypt, the excavators have not been so fortunate, but at least we know that even settlements of moderate size were well supplied with a variety of metal-working craftsmen.Footnote 17 None of this, once again, means that many provincial communities were as well supplied as Pompeii; the evidence referred to is merely impressionistic.
Such conditions did not last forever. A half century ago, a posthumously published book by a masterly Annales historian, Maurice Lombard, argued that shortages of metals, especially base metals that were needed for armaments, crucially weakened the late Roman Empire. In the late 6th c., the Byzantines, compelled now by their enemies’ fighting methods to rely more on cavalry, found themselves more and more short of iron for armor and weapons.Footnote 18 In 1972, the geochemist C. C. Patterson had argued, quite differently, that over-production of silver in the Roman Empire, necessitated by unavoidable coin loss, caused a shortage crisis by the 3rd c., and that this shortage was “intimately related to the decline of the Roman empire and the economic chaos of the Dark Ages in Europe.”Footnote 19 Not perhaps a very plausible argument. Long before that, in 1935, Oliver Davies, a scholar with a profound knowledge of Roman mines in Europe, had claimed that “the archaeological evidence suggests that the western empire became bankrupt mainly owing to the failure of its mines.”Footnote 20
Such theories no longer have much resonance in general histories of the late Roman world, if they ever did – with an important exception, dated 2001, to which I shall come in a moment. The second edition of the Cambridge Ancient History, for example, showed some interest in the matter with respect to the 3rd c., but volumes XIII and XIV, covering the years 337 to 600 CE, none, or extremely little.Footnote 21 And, for the most part, the experts on the metal artifacts of the Roman Empire have shown themselves quite uninterested in the historical changes involved in the production and availability of the artifacts in question.Footnote 22
Numismatists, meanwhile, have commented at length on the debasements and decreased weights of Roman coins in each of the three sub-periods under discussion in this article (for these sub-periods see below, p. 6), and have sometimes linked such changes to a depletion in metal resources.Footnote 23 Whether this is generally the best explanation of the phenomena, we shall see.
The most ambitious argumentation, however, is owed to Michael McCormick, who in his Origins of the European Economy (2001) maintained that one of the principal symptoms or causes (it is not clear which) of the decline of the late Roman economy was “lessening metal production,”Footnote 24 with respect to both precious and base metals. “The third century saw a steep decline” in Spain and Britain, “which cannot be explained by exhausted mineral lodes” (why not?).Footnote 25 All sorts of mines were operating in the late 4th c. in both Europe and Asia Minor, but “by around 400, things again began to look pretty dim” [sic].Footnote 26 The reason, supposedly, was declining demand, plus a probable labor shortage, aggravated by heavy taxation. How these assertions stand up to critical examination we shall consider period by period. Be it noted at once, however, that the dates indicated for “the last documented production” of metals at various places are often very misleading.Footnote 27 And this author has to recognize, somewhat inconsistently, that the 6th-c. eastern empire was by no means lacking in metal sources.Footnote 28
The ultimate aim then is to discover whether the depletion of metal resources and the ability of Romans to make use of them contributed to a significant degree to the decline of the imperial power between the 2nd c. and the 7th. And also, taking a cue from Bryan Ward-Perkins’s important book The Fall of Rome, to discover whether this depletion affected the material quality of everyday life.
Three other preliminary remarks. In the first place, while objects made of base metals, iron in particular, not being very valuable, may easily “disappear,” as building material, for example, or as broken weapons or discarded utensils, precious metals are looked after; they may disappear into private hands or across the frontier but they are much less likely to be forgotten.
Ore extractable from a mine or a mining area at tolerable cost eventually gives out, but the very concept of “exhaustion” needs parsing. Mine owners and their agents often had to decide whether it was worth working a particular mine: thus, for example, at Riotinto in southwest Spain “a heap of argentiferous jarosite ore, assaying at about 100 ppm of silver was found in a Roman gallery”; studies of the local slags “suggested that the Romans could not easily recover silver from ore below about 150 ppm.”Footnote 29 The slag that resulted from Roman lead mining in the Mendips still in the 19th c. had 20–26% of lead.Footnote 30 And a mine or set of mines might of course cease to be worked intensively when other mines could produce the same ores more profitably, as happened when, according Strabo, north Italian mines were partly supplanted by Iberian and Gallic ones.Footnote 31
It also has to be said that the existing scholarship concerning Late Antique metal production has been very seriously distorted by undue emphasis on the Roman Empire’s far west (Iberia) and far northwest (Britain), at the expense in particular of sources in Anatolia, the Middle East, and the Maghreb. Balkan production has been widely researched, and neither Anatolia nor the Middle East has been entirely neglected, but the imbalance is severe.Footnote 32 Yet we know, for instance, more than 800 silver/lead mines have been reported from the Bolkardağ region in the Taurus mountains.Footnote 33
Periodization
There has been a harmful tendency among those who have interested themselves in this topic to slide from one period to another within the history of the later Roman Empire.Footnote 34 We can usefully distinguish the following three periods without ignoring the intervals between them. These are the periods of greatest military stress, with the exception that the first of the three includes the era of the Tetrarchs and Constantine, when the currency system underwent a fundamental revision.
A first period to discuss can run from the reign of Commodus to that of Constantine (180 to 337). It appears to be an idée reçue that there was “a peak of Roman mining activity” in the first two centuries CE.Footnote 35 What did the subsequent decline amount to?
Later, during the Germanic and other invasions, say from the 360s down to the death of Attila in 453, the regions that had supplied the western Roman Empire with metals came, almost all of them, under the control of invaders or were in any case no longer under the control of what remained of the Roman government in Italy. From Iberia to Britain to Gaul to the western Balkans, mines ceased to function, or if they functioned it was mainly for the benefit of the newcomers.Footnote 36 Yet the consequences of these events, with respect to both the currency and armaments and civilian needs, are badly in need of clarification. Was it by now possible for the Roman Empire, whatever that term meant at any given date, to satisfy a large proportion of its appetite for metals by means of imports from the more secure regions or by means of recycling?
More than a century later still, the eastern Roman Empire experienced resource problems of its own. From late in the reign of Justinian (ob. 565) down to the great turning point in Eurasian history that came to pass in the last years of Heraclius (ob. 641) there was a pressing need for both precious and base metals, but the imperial forces were less and less able to defend the relevant territories. The failure of the Roman-Byzantines to defend their empire against the Persians and others, and in particular against the Arabs, is an intricate historical problem, and I do not intend to reduce it to a matter of metal resources, but the latter question deserves a better-balanced treatment than it has so far received. Historians of the 7th-c. Arab conquests have not yet paid sufficient attention to the vast mineral resources of the Arabian peninsula, now well-known to historians of Islam.Footnote 37
Evidentiary problems
(i) Problems in the archaeological evidence. The material evidence – mines and their associated settlements, metal artifacts of all kinds, evidence of pollution recovered from ice cores and peat bogs – is enormous in quantity but it is permeated by historical difficulties.
In the first place, ancient mining sites were commonly complex, many workings over whole districts, and in very many cases the evidence for ancient activities has been more or less thoroughly destroyed by modern industry. Furthermore, mining districts are “often… parts of an even larger unit,” the mining region, “that assembles different production and functional units on the larger scale of a landscape.”Footnote 38 Hence writing the history of any given mining region as a whole is extremely challenging.
Then there is the question of chronology. Dating the period during which an ancient mine or group of mines was active is always (not just in some cases) very difficult,Footnote 39 more difficult indeed than scholars have sometimes realized. The Oxford Roman Economy Project’s database of mines listed 551 sites when last consulted, but it provides virtually no useful chronological information (it offers innumerable chronological question marks), claiming, however, that mines in Dacia were not worked before the Roman conquest – which would make Trajan’s aggression unintelligible – or after the loss of the province ca. 271.Footnote 40
Sometimes it is possible to specify a significant terminus ante quem for the time when a mine came into use or a terminus post quem for when a mine ceased to be exploited, but it is never possible to say on archaeological (or any other) grounds when a particular ancient mine or group of mines ceased to be exploited, even when the site has been explored by experienced scholars with the full range of contemporary technology and information. Alfred Hirt has described the difficulties succinctly.Footnote 41 And there is always the possibility that a mine was worked spasmodically, that is, for a few years and then again later for a few more, because of changing conditions with respect to demand, security, or labor.Footnote 42 Settlements associated with mines are of course easier to date, usually, however, within broad limits.
A few examples will suffice. Take for instance the gold, silver and lead mines near ancient Ulpiana in Kosovo, where careful investigation has left us with no firm chronology at all.Footnote 43 Or take the Dolaucothi gold mines in southwest Wales: according to one view they were exploited “until the early second century,” but some of the associated pottery goes down to the 3rd c. and the latest coins date from the reign of Gratian.Footnote 44 At the well-known site of Vipasca (Aljustrel, south Portugal), which was mainly a source of silver, another site that is generally thought to have become less active in the course of the 3rd c., there was still some activity in the late 4th and early 5th c. – but how much?Footnote 45
Another evidentiary problem is obvious as soon as we turn our attention to the role of metal artifacts in the private lives of ordinary people. Without a Late Antique Pompeii, we are somewhat at a loss. The so-called Earthquake House at Kourion in Cyprus was destroyed suddenly at some date in the period 370–380. It was of substantial size, covering an area of 397 m2, occupied by “two, or possibly three, residential groups.” Its contents included 52 assorted metal objects (plus hundreds of coins) – some pitchers, but not much kitchenware. The impression is that though Cyprus had enjoyed a very long period of peace, this house was less well provided with metal artifacts than a Pompeian house of comparable size. But it is only an impression.Footnote 46
More than two centuries later, apparently in 616 or 617, the city of Sardis was effectively destroyed by the Persians.Footnote 47 A street of shops has been carefully excavated. “Large quantities of nails were found in all the Shops… Tools… and agricultural implements… frequently occur…. Iron locks occur… but copper alloy locks are far more common. Iron folding chairs lay in the upper story of E 7…. Copper alloy objects form by far the largest group of metal finds from the Shops. The principal objects recovered were censers…, over 100 locks…, steelyards…, and buckles.”Footnote 48 J. S. Crawford explicitly compared the site with Pompeii and Herculaneum with respect to metal finds, and as he said, “the differences seem surprisingly small.”Footnote 49 Aphrodisias too in the early 7th c. still seems to have been quite well supplied with base metals.Footnote 50 The material from Anemurium (coastal Cilicia) also suggests that private material life was holding up reasonably well in this region until approximately 600.Footnote 51
A quite different set of archaeological problems confronts us when we turn to the contested field of lead isotope analysis (LIA), which for 50 years has been setting out claims to tell us where the copper and lead came from that Greeks and Romans used. Yet the most persuasive recent account of the matter is disappointing for the historian of the ancient European and Mediterranean worlds: its authors argue that “in regions where most ore deposits are of similar geological age – as in the Andes, Europe and the circum-Mediterranean – provenance analysis with Pb isotopes is inherently difficult because geographically distant sources often exhibit similar isotopic ratios.”Footnote 52 And as recycling tended to increase, the question of provenance obviously becomes more difficult still.
(ii) A note on the textual sources. The only ancient text of the later empire that comments directly on the overall supply of any metal is owed to Cyprian, bishop of Carthage. Writing in 252 or 253, he includes in his account of the world’s supposed decay the supposedly declining production of gold and silver: “mines that have now been exhausted provide smaller supplies of silver and gold, and wretched veins are worked out in single days and shrink.”Footnote 53 This claim about mines has been rejected on altogether insufficient grounds.Footnote 54 Cyprian was not an unreliable fantasist like his fellow North African Christian, Tertullian, and his remark is very likely to have had some basis in reality at the time when he wrote. But, as will shortly become clear, his information was – not surprisingly – incomplete: it probably came, at least for the most part, from the Maghreb and from Spain.
Late Antique literary sources seldom, quite naturally, show any interest in such matters as the supply of metals. Military texts such as the anonymous De rebus bellicis (probably published between 366 and 370) and the Strategikon of the emperor Maurice (probably written not long after 592) are the most suggestive.Footnote 55 The law codes are sometimes useful. But no ancient writer provides us with an overview of any kind at any date.
(iii) Pollution. For 30 years now, environmental scholars and others have been making cheerful use of the evidence of metallic air pollution gathered from ice cores in Greenland, quite reckless of the fact, which was finally clarified in a pair of landmark papers published in 2017 and 2018, that the Greenland ice was affected vastly more by what happened in relatively close locations (the British Isles, to a lesser extent Iberia) and hardly at all by what happened much further away in the Middle East.Footnote 56 It had been widely assumed that the levels of pollution detectable in Greenland reflected the levels of lead and silver production in the Roman Empire as a whole.Footnote 57
Sometimes the pollution evidence fits evidence of other kinds and sometimes it does not; we need more interdisciplinary research. When, on the one hand, a team that investigated levels of lead in petrous bones recovered from the vicinity of Rome concluded that lead pollution there declined about 400 CE, that made sense.Footnote 58 When, on the other hand, another team concluded on the basis of evidence from a peat bog in western Serbia (Crveni Potok, in Roman Dalmatia) that lead pollution did not decline in the Late Antique Balkans but actually intensified between 400 CE and the early 7th c.,Footnote 59 something had apparently gone wrong. A less clear-cut case, based on data from central and western Europe, has claimed to detect decreases in lead pollution at about 200 and 425 CE, reasonably enough, but also claimed that the peak was reached in the time of Augustus, which is most implausible.Footnote 60 There will be more to say.
The state
Did the Roman state in fact run short of metals in any of the three periods described above?
(i) The state’s effective power. In all periods, it is likely that most mines belonged to the emperor while some did not.Footnote 61 A more important question for us is the extent of the state’s effective power, including its efficiency in exacting taxes. But hard facts are very few. On the one hand, conditions of civil war sometimes affected the most important metal-producing territories, in all three periods described above; on the other hand, it may be assumed that the central power always took a real interest in the exploitation of mines, especially those that produced precious metals – an interest that is attested in an imperial panegyric of 389.Footnote 62 It is obvious enough that while some emperors were effective at recovering metals from their subjects, Diocletian and Constantine for instance,Footnote 63 others were less so – they suffered from what has been called “fiscal inadequacy.”Footnote 64 The contrast is sharp between, on the one hand, the imperial government, sometimes worried, as we shall see, about the supply of gold, and, on the other hand, the vast quantities of gold sometimes possessed by the wealthiest landowners, most conspicuously in the last years of the 4th c. and the first years of the 5th.Footnote 65
Furthermore, the operations that brought metals from the rock face (or the placer mine) to the imperial treasury and the private market were complex and delicate, and easily upset. A constitution of 386 (CTh 1.32.5) claimed that in Macedonia, Dacia Mediterranea, Moesia, and Dardania – a large and crucial region – the tax-gathering procurators of the local metalla had failed in their duty because “they pretended to be afraid of the enemy.” It was all very well to say that in Milan; on the ground, the fears may have been real. It is likely enough that miners were often disaffected, as when in 378, Thracian gold miners sided with the Goths because of the burden of taxation (Ammianus 31.6.6). I will consider later the wider question of labor.
(ii) Invasions. Foreign invasions were much more harmful than civil wars; usurpers, after all, had no interest in interfering with mining activity. A full catalogue of relevant wars would require a whole volume, and here it is enough to recite the most important developments.
In the first of our periods, the most vulnerable mining regions were Transdanubian Dacia and the area of Upper Moesia between Viminacium and Ratiaria (a source of gold, silver, lead, copper, and iron). The latter seems to have been invaded periodically in the 250s and 60s (the sources are exceedingly poor).Footnote 66 From the late 240s, Dacia was under frequent pressure until it had to be abandoned ca. 271. It has also been hypothesized that Goths captured the entire Roman treasury at the Battle of Abritus (Lower Moesia) in 251,Footnote 67 and the Roman side certainly lost a lot on that occasion. The decreased purity of the aureus comes right after this. Thrace and Macedonia also suffered in 267.
That in the first decades of the 5th c. the important mining districts in Iberia, Gaul, and Britain passed permanently out of Roman control needs no immediate commentary. Rome’s loss of control in the Balkans is a more complicated matter, not least because it affected eastern as well as western Rome. The most important stages were probably the little-known operations of the Goths in Macedonia and Pannonia after their major victory at Adrianople in 378; then, after the death of Theodosius I in 395, the Roman situation rapidly deteriorated again:Footnote 68 that same year Alaric led Visigoths from Lower Moesia into Thrace, Macedonia, and Greece. His operations had the effect of removing most of Upper Moesia and Thrace, and some of both Pannonia and Macedonia, from Roman control (the geographical details are often obscure).Footnote 69 In 395, too, Huns from across the Caucasus attacked “Armenia and the Eastern provinces” (Sozomen 8.1, supposedly on a large scaleFootnote 70 ). In 398 (probably), the emperor Arcadius essentially surrendered a large portion of the western Balkans by awarding Alaric the title comes Magister militum per Illyricum. Vandal and Alan raids afflicted Noricum, always a rich source of metals, in the winter of 401/2. The last Roman official who exercised any real power in the western Balkans may have been Generidus in 409.Footnote 71 After a brief period during which east Rome was in command of the middle Danube lands, the whole large area fell to Attila in 441.
The forces of Justinian recovered much of North Africa and Italy and a part of Spain for the Roman Empire. But with the bulk of his quite limited forces committed in the West he was sometimes unable to protect the heartlands of the empire, and in particular the mining resources in the Balkans. Here I will start with the occasion in 559 when Slavs and Huns reached the outskirts of Constantinople. In 578–581, large numbers of Slavs invaded Thrace, Macedonia, and Greece, and in 585 and again in 588, Slav forces once more reached the outskirts of the capital. In the 590s the Byzantines did somewhat better in this region,Footnote 72 but it is hard to believe that many mines still functioned. In the early years of Heraclius, from 614, Moesia and Thrace passed definitively out of Byzantine hands. As to the eastern frontier, the Sasanian ruler Chosroes was at or near Caesarea in Cappadocia in 575, but it was only under Phocas that the Byzantines lost metallically important Armenia.Footnote 73 In 613, Cilicia fell to the Persians, and the following year the whole of Asia Minor was at their mercy. In 618–619, they conquered Egypt. The Byzantine recovery under Heraclius (622–630) was short-lived indeed.
Much has been written about Roman payments to external powers.Footnote 74 Some have argued that they were not a heavy burden,Footnote 75 but on occasion and in the end they probably were. What was bearable under Justinian was not bearable under Maurice or his successors. Since the 1st c. CE it had certainly been a normal and, one may say, rational policy to subsidize foreign states in order to protect the frontiers. Even relatively strong emperors sometimes did this: Diocletian, for instance, subsidized the Blemmyes in Upper Egypt (Procopius, Wars 1.19.32–33). The question here is whether such payments, which were largely in precious metals, strained Roman resources.Footnote 76 Since we cannot in my view calculate the state’s income or expenditure in any of our periods, we have to depend on indirect testimony. A statement that Ammianus attributes to Julian (24.3.4), to the effect that such payments were the reason why the state was impoverished (egentissima), must be given its proper weight. Later we hear of dramatic effects brought on by such payments in Priscus’ contemporary account of the payments to the Huns between 430 and 450.Footnote 77 The government raised extra taxes “so that formerly wealthy men offered their wives’ jewellery and their furniture in the marketplace,” and some committed suicide.Footnote 78
It is inconceivable that that Maurice would twice have reduced the cash wages paid to the soldiers (by one-quarter in 587/588, and by an unstated amount in 594)Footnote 79 except under financial duress, which is not to say that foreign subsidies were the only reason for his financial difficulties. The earlier reluctance of Justin II to make such payments may well have been a sign of trouble in this respect.Footnote 80 There can be little doubt that by the 590s the government was seriously short of precious metals. Phocas and Heraclius were in even greater difficulties. In 622, the emperor, “having taken the money of the holy churches as a loan…, seized the candelabra of the Great Church as well as other serviceable equipment and minted large numbers of gold and silver coins.”Footnote 81 The following year he had to pay the Avars a heavy tribute of 200,000 solidi and send along valuable hostages who later had to be ransomed.Footnote 82 In the 630s, Heraclius twice overruled subordinates who were paying gold to the Arabs to keep them at bay (out of Egypt and out of Osrhoene); the results were disastrous but possibly unavoidable.Footnote 83
(iii) The numismatic evidence. It often leaves open the question whether the authorities were short of precious metal or merely using it with sensible parsimony. These two possibilities should be distinguished: (1) The government debased the coinage and caused weight standards to decline because it could not obtain enough precious metals, via taxation, expropriation or mining, to meet its monetary needs.Footnote 84 Another possibility (2) is that the government debased the silver coinage and lightened the weight of gold and other coins quite voluntarily in order to save metal and spend extravagantly – as Nero certainly did; Trajan too. When Trajan obtained rich new supplies of silver from Dacia, he did not waste them on improving the fineness of his silver coins. A study of the brass coinage issued under the emperors Nero to Lucius Verus has suggested that its components were sometimes manipulated with intent to economize.Footnote 85
The second possibility can only be excluded when it can be shown that the government is likely to have run serious risks by implementing such policies. With regard to gold coins, that moment is likely to have arrived under Caracalla, when the aureus was reduced in weight after a long period of stability.Footnote 86 Under Gordian III, there was an even more drastic shrinkage,Footnote 87 and from 250 to 274, no definite standard at all. Furthermore the aureus was debased from the 250s till 294, though not by a huge percentage.Footnote 88 During the same period, roughly, more of the gold coinage seems to have been made of recycled gold,Footnote 89 not surprisingly. The reduced weight under Gordian III may be due to mere disorder, and the same applies to the later debasement; the reduced weight under Caracalla, however, was probably due to a temporary hiatus in the supply of metal. The fact that Diocletian and Constantine decided in effect to base the coinage system on gold indicates, however, that they did not anticipate any grave shortage of raw material.
As for the silver coinage, which had long been largely fiduciary in nature, its debasement (much harder for people to detect than the debasement of gold) was largely unproblematic, so it seems, until 260.Footnote 90 If Claudius II and Aurelian had been more provident, they would not have debased the silver coinage still further; the new, less-debased silver coins of 275 and later contained only a little more silver, which suggests at least that less of it could now be mined. A major change in monetary policy ensued, but it was a slow one, still going on in the mid-4th c. An attractive hypothesis aimed at explaining the enormous price increases that occurred in 353/4 suggests that they resulted from the government’s elaborate attempt to recover a very large amount of silver from the billon coins in circulation.Footnote 91 The fact that from the early years of the 5th c. down to Heraclius very little silver was coined can best be explained by a perceived shortage of the metal (no other plausible explanation has been offered).
The coinage of the emperors from Maurice to Heraclius presents an apparent paradox. As we have seen, there are strong reasons to suppose that all three emperors concerned were hard-pressed financially, and Heraclius’ new reliance, from 615, on the silver hexagramFootnote 92 confirms this.Footnote 93 But there is suggestive evidence, in the form of die-stamps, that Heraclius actually minted gold in much greater quantities than his predecessors. The explanation is likely to be that Heraclius centralized the gathering and expenditure of tax revenue, which had in part been controlled by regional officials employing existing coins.Footnote 94
With regard to bronze, Justin II had already reduced the weight of the follis from 16/17 gr to 12/13 gr. In 615/616 it fell from about 11 gr to between 8 and 9 gr, and in 624/625 it fell further to a little over 5 gr, to stay there, apart from a brief period during the years of victory over Persia, for the rest of the reign of Heraclius.Footnote 95 This shrinkage was presumably caused by a shortage of copper and/or tin – in government hands.
(iv) Military effects. Did a shortage of metals dangerously restrict the size or effectiveness of Rome’s military forces? There can be no definite answers, not least because the actual number of Roman troops, from the late 4th c. onwards, is disputed over a very large range. By the 370s, at the latest, the army was in my view probably tending to shrink quite seriously,Footnote 96 and a principal reason is likely to have been financial. It is also thought that the increasing employment of outsiders (“barbarians”) as soldiersFootnote 97 meant more payments in cash, mainly gold.Footnote 98
We have no reliable numbers for the Byzantine armies of our third period.Footnote 99 The claim of the Armenian historian Pseudo-Sebeos, who aggrandizes Heraclius, that in 624 the latter led an expeditionary force of 120,000 across northern Asia Minor (p. 124 Abgaryan = p. 81 Thomson) was pure fantasy.Footnote 100 Those scholars who have considered the matter most carefully have generally concluded that the field army of Heraclius is unlikely to have exceeded 20 to 24,000 men. Contrast the 65,000 men whom Julian took to Mesopotamia in 363. It was primarily a shortage of money that kept the crisis-period armies quite small, so I have argued elsewhere.Footnote 101 And their cost was all the greater because of the increased reliance on cavalry that was imposed by the cavalry strength of most of Rome’s enemies.Footnote 102
Whether Roman armies of this period were reasonably well equipped is another question in need of further research.Footnote 103
(v) Transport. The main sources of metal ores were more or less far away from the great centers of population. Thus with respect to the transport of metals from mining areas to the market place one would ideally like to be able to estimate the state’s effective interest. At least we know that Roman roads, and therefore land transport, which was especially important for the transport of precious metals, deteriorated by fits and starts in each of the three periods under discussion.Footnote 104 In the high Roman Empire a significant quantity of iron and copper had also been transported by sea,Footnote 105 and it would be relevant to assess whether late-Roman harbors could effectively support such activity.
(vi) Statements about policy. It so happens that the second of our three periods provides us with some informed Roman policy advice about the supply and use of metals. Thus the courtier Themistius advised the emperor Julian to prohibit the use of gold and silver for making “furniture and utensils,” apparently in order to save these metals for making coins.Footnote 106 Another text of just these years (De rebus bellicis praef.10, of 366–370) sees the doubling of the gold and silver in government hands as a primary objective (sine dantium poena duplicetur).
(vii) Restricting exports. Periodically, starting as far as we know in the 3rd c., Rome attempted to prevent the export of certain metals.Footnote 107 Constantine allowed iron to be exported to hostile Persia in 337, when Sapor II asked for it (Libanius, Or. 59.67), but by mid-century there seems to have been a law against selling aeramen (bronze or copper) or iron to “enemies.”Footnote 108 Decades later Valens banned the export of gold, and even encouraged Romans to try to trick the “barbarians” into parting with it (CJ 4.63.2 of 374),Footnote 109 which suggests something close to panic; and this law remained in force under Justinian. In Procopius’ time the export of iron was a capital offence, at least on the eastern frontier (Wars 1.19.24–26; CJ 4.41.2). Objects made of copper and copper alloys, on the other hand, seem to have been exported quite openly and in considerable quantity in the last of our three periods.Footnote 110 Which may perhaps suggest that it was fiscal inadequacy not depletion of resources that led to the shrinkage of the follis.
Demand and supply
The demand factors that affected late-ancient metals have already been mentioned, albeit briefly. A fuller account would enlarge on the needs of the civilian economy, agricultural and artisanal, including construction, and it would extend to household goods of all kinds, and to trade beyond the frontiers,Footnote 111 all of which needs were subject to demographic fluctuations.
Another important topic is the demand, in the second and third of our periods, for religious equipment and adornment of all kinds. By the 5th c., if not earlier, very considerable quantities of gold and silver, but chiefly silver, were going out of circulation in churches.Footnote 112 Yet it remains hard to say whether the use of gold and silver to equip and decorate churches had a significant effect on other uses. The quantities in question are sometimes striking, but it may be that the government suffered no more than marginally.Footnote 113
Then there is the question of coin loss – the percentage of the coinage that for one reason or another went out of circulation each year, as happens all the time in all coinage systems.Footnote 114 But there is no way of showing that this phenomenon caused any particular event, such as Caracalla’s lighter aureus.
Now for a list of the supply factors (we have already discussed security); here we reach the center of the discussion.
(i) Depletion of metal ores. As already noted, what counts as depletion depends on the available extractive technology. Quite apart from the fact that the most accessible deposits can in general be assumed to have been depleted first,Footnote 115 the most useful ores may well have tended to become significantly rarer. With respect to the copper used in coins, for example, sulfide ores are said to have replaced oxide ores, which are much easier to work and require less in the way of investment; this change is said to have begun slowly ca. 116.Footnote 116
(ii) Fuel. Smelting and metal-working required vast quantities of wood fuel in the form of charcoal, and this was I suspect a gradually more and more vital factor. The normal pattern of Roman metal production seems to have been, quite naturally, that the ore was processed to produce metal as close as possible to the mine site;Footnote 117 then ingots were transported to the population centers where demand was concentrated. That meant that every considerable community, all over the Roman world, required fuel for the actual manufacturing processes. In spite of recent work, however, we are not yet able to write a satisfactory empire-wide history of deforestation.Footnote 118 We know that it was possible to mine and manufacture metals even in Egypt, where the felling of trees was carefully controlled and much timber was imported.Footnote 119 But maintaining an adequate timber supply required expertise and planning, and it may be doubted that there was enough of either in the empire of our period III.
The chief difficulties here are not to know how much charcoal was needed to produce given quantities of metal or metal artefacts, though that is complicated enough.Footnote 120 What is more difficult still is to know (a) the likely annual production of metals at any given period, and (b) the quality of woodland management (which should not be treated as a constant). It is sometimes said that the high Roman Empire produced annually some 82,500 tons of iron – a figure that derives, via very dubious reasoning, from an unpublished MA thesis of long ago.Footnote 121 I calculate that the annual production of 82,500 tons of iron would have required all the wood that could be taken from very approximately 27,000 km2 of coppiced woodland,Footnote 122 and in reasonably convenient places (because of the high cost of land transport). (For comparison, the entirety of Sicily comes to 25,832 km2.) According to the careful calculations of J. E. Rehder, production of iron on this scale would have required some 12.375 million tons of biomass every year.Footnote 123 That would have required an even larger area of woodland. Consider furthermore the need for fuel to produce other metals – probably at least as much again – and, in addition, the fuel needed to make bricks and pottery. Yet the ubiquity of heated baths in the high Roman Empire shows that there was no severe shortage.Footnote 124
The other great iron-producing culture in ancient times was China. No expert scholar now seems willing to estimate Chinese production prior to the Song dynasty (960–1279), at which time, according to one calculation, the province of Sichuan (Szechuan), one of a number of iron-producing provinces, turned out 1.2 kg per capita a year, generally agreed to be a major increase over earlier times.Footnote 125 That encourages one to doubt that the Roman Empire ever consistently produced as much as 82,500 tons of iron a year, least of all in our Period III. But it is also to suppose that the order of magnitude is probably correct, and the constant pressure on timber resources, especially perhaps in periods of large-scale warfare, should not be in doubt.Footnote 126
As for the quality of woodland management, the only way of measuring it is probably by studying pollen deposits, but we would need a number of such studies. In an earlier study I hypothesized a decline of this kind in Period III, but none of the areas that provided the evidence (in Libya and Spain) were still under Roman control when the decline took place.Footnote 127
(iii) Technological progress. It may be presumed that since the most easily worked deposits tended to be worked first, the real costs of ancient mining must always have tended to rise,Footnote 128 unless, that is to say, there was counter-balancing technological progress. Barring such improvements, prices would rise and consumption decline.Footnote 129 It is apparently impossible, as far as existing knowledge goes, to isolate any significant improvement in Roman mining or metallurgical technology that occurred after the 1st c. CE.Footnote 130 But that is not the end of the matter: it is the application of known technology that matters, and the history of this process has still to be written.
(iv) Investment. Placer mining for gold required a minimal investment, but that was an exception. The investment required to make a mine productive must always have been considerable, involving labor of several kinds, engineering works, transport, and whole settlements.Footnote 131
(v) Prospecting. Texts tell us very little about this.Footnote 132 An older view supposed that “the ancients” were severely deficient in this respect,Footnote 133 and this will not surprise anyone who has read about gold and silver prospecting in the 19th c.,Footnote 134 or about modern methods.Footnote 135 Recent opinion, however, has been much more favorable, and it has been said that the Romans discovered almost all the metal deposits that they could make use of.Footnote 136 In the entire Roman Empire there seems to be only one important metal-producing area that was exploited in the Middle Ages and not much if at all by Romans, namely Melle in northwest France, an important source of silver under the Carolingians.Footnote 137 In short, there was not a great deal left to find without radical new developments in geology.
(vi) Labor. In the first place it is important to realize that mining and metallurgy depended not only on miners but on highly skilled engineers, managers, equipment makers, and the experts who processed each of the metals in question.Footnote 138 If for any reason the expert workers in mining, smelting and forging die or flee or fail to train successors, a serious though not necessarily permanent breakdown occurs.
Some scholars have maintained that a very large proportion of Roman miners were free persons.Footnote 139 That may have been true about gold miners,Footnote 140 but is unlikely to have been the case with those who produced base metals, most of whom were, in all likelihood, slaves, convicts, or persons subjected to corvée labor; in Late Antiquity some will also have been what are commonly called coloni, people tied to the occupations of their fathers.Footnote 141 Hence a full discussion would involve the complex history of slavery and the colonate over all our periods. Some mine-workers will always have been women and children.Footnote 142
It is not to be supposed that there was a serious shortage of convict labor in any of our periods.Footnote 143 The sheer range of offences for which one could be sent to the metalla would astonish anyone unfamiliar with the brutality of Roman criminal law in later antiquity.Footnote 144 As for slave miners, there is no clear evidence. Pope Gregory (r. 590–604) still bought and sold slaves as a matter of course,Footnote 145 and warfare and other practices always replenished the slave population – more or less. The concentration of legal rulings concerning gold miners from 365 to 424 suggests, plausibly enough, that the rulers were worried about the supply of that substance and the number of miners (but our lack of later evidence does not mean that they were no longer worried).Footnote 146 Alas, that tells us nothing about the supply of labor in silver or base-metal mines.
(vii) Recycling.Footnote 147 That imperial Romans commonly recycled base metal artifacts is generally accepted and unsurprising.Footnote 148 But did the practice intensify in any of our three periods? At Emona (Slovenia) there appears to have been an increase in recycling in the 4th c.Footnote 149 Robin Fleming has pointed out that some smiths in late 4th-c. Britain turned increasingly to scrap,Footnote 150 but we cannot (yet) tell how widespread that phenomenon was in any period.
(viii) Imports. Metals were certainly imported from Britain into the Roman Empire prior to the conquest, and there were in all periods significant resources beyond the imperial frontiers. In the Periplous of the Red Sea (1st c.), the Roman Empire is an exporter of metals not an importer, but the casual and minimal evidence we have for the import of metals in our latest period suggests that the balance had shifted. It would be surprising if none of the gold acquired by the Axumites in east Africa made its way into Egypt.Footnote 151 An often quoted story in the life of John the Almsgiver (who died about 620) mentions a ship that was supposed to bring tin from (southwest) Britain to Alexandria (ch. 8);Footnote 152 but tin was rarer around the Mediterranean than any of our other metals.
Thus we may say that a supply crisis might be caused by a depletion of resources, but also by wartime conditions in the area(s) in question, by a lack of investment, or by a shortage of wood fuel (these two factors go together), or (less probably) by a shortage of labor.
Overview
In the future it should be possible, in spite of the chronological problems mentioned earlier, to calculate the correlation between the date when mining districts began to be heavily exploited and their distance from major centers of demand (their distance in terms of cost per kilogram/kilometer for the carriage of smelted ore). Take for example the iron production of Lercoul in the French Pyrenees: it was heavily worked from the 3rd or 4th c. onwards (opinions differ), but it is hard to get to now, and transport down the valleys must have been quite costly in antiquity.Footnote 153 A clear sign therefore that the cost of iron for the consumer in Gallia Narbonensis was on the rise. But that leaves open the question whether Lercoul was necessary because of the depletion of ores in more convenient places or for some other reason such as the depletion of wood fuel.
Period I (180–337). As far as gold is concerned, three facts overshadow all others, Caracalla’s reduction of the weight of the aureus, the loss of Dacia, and the dominance of the solidus that began with Diocletian and Constantine. The reduction in 215 presumably means that there was a crisis of supply, probably centered in Spain,Footnote 154 and not easy to explain except as a result of depletion in that region. But there were many other sources, in Italy, Noricum, Thrace, Britain, Upper Moesia, Dacia, and Asia Minor, and once the aureus had been lightened there was no reason to make it heavier again. The decision of Diocletian and Constantine to base the coinage system on the solidus shows that they did not foresee any grave problem of gold supply. It is quite curious that the loss of Dacia did not have a greater effect; the probable reason is that its production declined in stages, first after the Marcomannic war, then again after the Severi.Footnote 155
The supply of Iberian silver was under strain by late-Severan times, as the evidence for diminishing pollution seems to show, but production at some important sites in the peninsula continued,Footnote 156 and alternative sources were, as Pliny had indicated, quite numerous.Footnote 157 By the 250s, however, the numismatic evidence accords with the evidence of Bishop Cyprian to suggest that supplies in the empire as a whole were insufficient. That might be seen as a result of war conditions in mid-century, but the decisions of Diocletian and Constantine to put gold at the center of the currency system points to a lack of confidence in the supply of silver (scarcely surprising after more than 500 years of heavy Mediterranean-wide exploitation).Footnote 158 Nothing in the later history of Roman silver contradicts this notion.
As to base metals in this period, some iron mines apparently went out of use, most notably in the Gallic provinces (a highly disturbed region from time to time in the 250s and 270s),Footnote 159 and there may have been regional dislocations, but there is no evidence of a general crisis.Footnote 160 That is not merely an argument from silence: in Egypt (which had little iron of its own), nail prices show that there was no new shortage of iron there in the 3rd c.Footnote 161 As to copper, the most interesting numismatic phenomenon of this period is the cessation of civic bronze over the course of the century, a process virtually completed by the 260s; but this is probably to be explained by an urge towards centralization rather than by a shortage of raw material.Footnote 162
Period II. By the time of Julian, however, the government was apparently suffering from a certain shortage of gold and silver, as we have seen.Footnote 163 That was probably due in large part to the exhaustion of easily workable deposits. Later, especially after the death of Theodosius I in 395, the emperors lost control to a significant degree of the relevant territories in the west and in the Balkans.Footnote 164 We have noticed Theodosius II’s payments to the Huns. There is also some evidence that the price of gold, in terms of other metals, had risen by 384 and again by 422.Footnote 165 Theodosius II had apparently leased Armenian gold mines to the Persians prior to 421, but when they refused to give them back he went to war.Footnote 166 Yet the composition of the solidi shows that there was a significant new source of gold put to use from the 350s onwards (its whereabouts is obscure), and we should diagnose a shortage of moderate severity caused in part by a certain depletion of raw material.Footnote 167
With regard to silver, it is apparent that its diminished use in 4th-c. coinage and its virtual disappearance from the coinage of the subsequent two centuries are plausibly to be attributed to a drastic decline in mining productivity.Footnote 168 The late 4th c. is of course the apparent heyday of silver plate, the time when all or most of the components of the Kaiseraugst, Esquiline, Seuso, Trier, Mildenhall, Hoxne, and Vinkovci treasures were made, also the Traprain Law Hacksilber.Footnote 169 Eleven sites for making silver plate are known, from Cologne to Antioch and there were certainly more.Footnote 170 All this was no doubt made easier by the fact that the state no longer had much use for this substance.
From a military point of view, iron was crucial. Restrictions on exporting itFootnote 171 were probably outward-looking rather than inward-looking.Footnote 172 What is frustratingly difficult to know is whether the cessation of activity at certain iron-producing sites prior to the invasions of this period were typical and consequential. Some mines ceased activity,Footnote 173 but it is seldom if ever clear why, and in significant regions such as Asia Minor and the Maghreb, evidence is minimal. A typically frustrating site is Maslovare in the Japra valley in Bosnia (in Roman Dalmatia), where iron-working expanded considerably in the 3rd c. but seems to have collapsed gradually in the 5th, partly no doubt because of barbarian invasions, partly perhaps for other reasons.Footnote 174
Similar evidentiary problems make it impossible to follow the history of copper and bronze in this period. It is evident that copper production at Wadi Faynan in Jordan slowed down drastically by the end of this period, but other sites may have picked up the slack.Footnote 175 The Roman world’s principal source of tin, southwest Britain, ceased to produce on a large scale about the time when Roman power withdrew.Footnote 176
Period III. Tiberius (II) still seems to have disposed initially of adequate supplies of gold, since the emperor gave away large sums, much to the dismay of his adoptive mother Sophia.Footnote 177 Under his successor Maurice, even when the state had had time to recover from this generosity, there were unmistakable signs of a severe shortage of gold in government hands, as we have already seen. In the territories that were still more or less firmly under the control of Phocas and Heraclius prior to the Persian invasions during the reign of the latter, gold can only have been produced in notable quantities in Lydia, Pontus, and Egypt,Footnote 178 but our only useful evidence comes from Egypt. It is probably symptomatic that the low-yield gold mines at Bir Umm Fawakhir in the eastern desert were still considered worth working.Footnote 179 All this of course leaves it quite unknown how much gold was in private or ecclesiastical possession; the biographer of John the Almsgiver claims that when he became bishop of Alexandria in 606 he found that his predecessor possessed as much as 8,000 lbs of gold – which is startling but possible.Footnote 180
Since very little silver had been coined for more than two centuries and very large quantities of silver were now in ecclesiastical hands all over the empire,Footnote 181 it was relatively easy for Heraclius to introduce the hexagram (see above), which he proceeded to issue “in considerable quantities.”Footnote 182 Chosroes II was supposedly able to exact 120,000 lbs of silver (approximately 39 metric tons) from the churches and people of Edessa ca. 624.Footnote 183 The volume of hexagrams “trailed off” in the 680s,Footnote 184 but by then the Byzantine state was a fraction of its former self.
With regard to iron, we can see that production at various sites declined or ceased ca. 600, and sometimes, as in the previously mentioned case of the Japra valley in Bosnia (p. 25), this was evidently because of invaders.Footnote 185 In the case of Sagalassos in Pisidia (southwest Turkey) – a site that has been investigated in detail – while iron production is said to be documented “until the mid 7th century AD,”Footnote 186 the place was in evident decline from the mid-6th c. onwardsFootnote 187 – for debatable reasons that may well have included a certain depletion of usable iron ore.
In the case of copper, the diminished weight of the follis (above, p. 15) suggests that as early as the reign of Justin II and later down to that of Heraclius, it was in short supply. That runs counter to the current consensus concerning copper production in Cyprus, according to which “it is now generally accepted that it extends until the end of the 7th c. CE and perhaps well into the 8th c. CE.”Footnote 188 According to another account, “there was a real boom in the copper industry [in Cyprus] in the period between the 4th and 7th centuries AD. Indeed during this period production was of truly industrial scale.”Footnote 189 But the evidence that this was still true after 600 is fragile and needs further discussion.Footnote 190 At Wadi Faynan, production seems to have shrunk or practically ceased after about 450.Footnote 191 Meanwhile, under Phocas, at least nine mints, from Ravenna to Antioch, were in need of copper in order to produce folles;Footnote 192 it is hard not to suspect that the metal itself was in short supply, at least in some parts of the empire.
A final enigma may prepare the reader for the tentative quality of my conclusions. Yassıada A is one of the best known Late Antique shipwrecks. It sank in or shortly after 625 off the coast of Caria. A vessel of roughly 60 tons burden,Footnote 193 it carried about 900 amphorae, no weapons (apparently), but 11 iron anchors and a remarkable number of other metal artifacts;Footnote 194 in fact it reminds one of the Sardis shops mentioned earlier (p. 9).
The medieval future
That bronze, not to mention other metals, continued to be in short supply in the dramatically reduced Roman-Byzantine empire of the late 7th c. is nicely illustrated by the fact that in 663 Constans II (in reality a petty ruler based in Syracuse), visited Rome for 12 days and “pulled down everything that in ancient times had been made of bronze (aere) for ornament of the city, to such an extent that he even stripped off the roof the church of the blessed Mary which at one time was called the Pantheon… and he took away from there the bronze tiles and sent them with all the other ornaments to Constantinople” (Paul the Deacon, Hist. Lomb. 5.11) (this material failed to reach its destination however).Footnote 195
But the most striking medieval development is that, in diverse regions, mines, or at least mining areas, that are known to have ceased to function in Late Antiquity came to life again. Lombard already pointed out that the Arabs found ample sources of iron in Spain;Footnote 196 it is not entirely clear to me, however, that there was a hiatus in silver production there between late-Roman times and the undoubted production under the Visigoths and the Arabs.Footnote 197 Elba on the other hand is a clear case: iron mining collapsed in the 1st c. BCE or CE but picked up again in the 11th c.Footnote 198 The only possible reason why this could occur is that wood resources, there or nearby, were now once more sufficient. This was in fact part of a revival of metal production in northern Tuscany that had started in the previous century.Footnote 199 Similarly in the Weald (southeast Britain): iron production had ceased to be important in the late 3rd c.,Footnote 200 long before the Roman army left the island, but it started again 10 centuries later;Footnote 201 the most likely reason for the hiatus is that the ample wood resources needed were no longer available within a tolerable distance.
Tentative conclusions
Lombard and McCormick, so it seems, were on the track of real economic and military developments, but these did not take the shape that they supposed.Footnote 202 A more nuanced investigation, while it has to leave many questions unanswered, chiefly suggests the following: (1) a serious shortage of silver in government hands in the 3rd and 4th c., probably caused at least in part by a depletion of ore deposits; (2) a variable shortage of gold in government hands throughout our period II, caused in part by a depletion of resources; (3) a serious shortage of gold in government hands from the reign of Maurice onwards, caused once again, at least in part, by a depletion of resources; (4) a shortage of copper, of uncertain origin, from the reign of Justin II onwards. On the other hand, we have not found strong evidence of a generalized shortage of iron in any of our three periods. Lastly, it is to be supposed, subject to further investigation, that a shortage of fuel gravely interfered with metal production in the last of our periods, and perhaps earlier.
Acknowledgments
I wish to dedicate this article to the memory of my extraordinary friend Ronald Findlay (1935–2021), for many years a professor of economics at Columbia. Quite a number of scholars and scientists have very kindly helped me along the way with information and learned advice: I especially wish to thank Isabel Barton, Gregor Borg, George Green, Anne Hunnell Chen, Michael Kulikowski, Paolo Malanima, Gaspard Pagès and Ernst Pernicka – but above all Andrew Wilson.
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