The Denarius in the Second Century - Royal Numismatic Society

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The Beginning of the End? The Denarius in the Second Century

by

KEVIN BUTCHER and MATTHEW PONTING

THE DENARIUS IN THE SECOND CENTURY 63

The Beginning of the End? The Denarius in the Second Century

KEVIN BUTCHER and MATTHEW PONTING

THE SECOND century tends not to receive much notice in monetary histories of the Roman empire.1 After recognising the first century debasement of the denarius and reduction in weight of the aureus by Nero, followed by the raising of silver and gold standards under Domitian and the debasement under Trajan, general accounts tend to skip to the end of the Antonine age, before describing the debasements and changes of the third century.2 At most, the second century is acknowledged as a period of decline, provoked by a shortage of silver and excessive expenditure. It marks the start of the downward slide leading to the third century ‘collapse’ of the coinage.

Scholarly reluctance to engage with the detail is not particularly surprising: until recently, the only survey of the fineness of second century denarii was that of David Walker, and this seemed to show that the silver coinage was produced at variable

1 We are grateful to the Arts and Humanities Research Council, UK, for the funding that underpins the research for this paper (Grant No. 119434). The coins analysed for this article come almost exclusively from hoards: the Baeretswil hoard, Switzerland (see J. Diaz Tabernero, R.C. Ackermann, B. Zäch, C. Hauser Pult, B. Hedinger, ‘Der römische Münzhort von Bäretswil, Adetswil-Pulten 1993’, in Archäologie im Kanton Zürich, 1995-1996, Berichte der Kantonsarchäologie Zürich 14 (1998), pp. 73-136); the Brislington or Bristol (St. Anne’s) hoard (H. Mattingly, B.W. Pearce, ‘The Bristol hoard of denarii’, NC5 18 (1938), pp. 85-98); the Magiovinium or Bletchley (or Little Brickhill) hoard (M. Crawford, ‘Bletchley treasure trove of Roman imperial denarii’, NC7 9 (1969), pp. 113-22; T. Tuckett, ‘Bletchley, Buckinghamshire’, in R. Bland (ed.), The Chalfont Hoard and Other Roman Coin Hoards (London, 1992), pp. 50-64); the Prestwood A hoard (R. Abdy, ‘Prestwood A, Buckinghamshire’, CHRB 11 (2002), pp. 163-8); and the Shapwick Villa hoard (R. Abdy and S. Minnit, ‘Shapwick Villa, Somerset’, CHRB 11 (2002), pp. 169-233). A few other coins come from the collections of the British Museum, Manchester Museum, and the Münzkabinett und Antikensammlung der Stadt Winterthur. We are very grateful to the following for their support and assistance: Stephen Minnit (Somerset Museums); Gail Boyle (Bristol City Museum and Art Gallery); Brett Thorn (Buckinghamshire Museums); Benedikt Zäch and Ulrich Werz (Winterthur); Richard Abdy (British Museum); Keith Sugden (Manchester); and Chris Somerfield (University of Nottingham).

2 E.g. M. Crawford, ‘Ancient devaluations: a general theory’, in Les Dévaluations à Rome, I (Rome, 1975), pp. 147-158; J. Kent, ‘The monetary system’, in J. Wacher (ed.), The Roman World, Volume 2 (London, 1987), pp. 568-83, at p. 575; K. Verboven, ‘Demise and fall of the Augustan monetary system’, in O. Hekster, G. de Kleijn and D. Slootjes, Crises and the Roman Empire. Proceedings of the Seventh Workshop of the International Network, Impact of Empire (Nijmegen June 20-24, 2006) (Leiden, 2007), pp. 245-57, at p. 246; J. C. Martinez Oliva, ‘Monetary integration in the Roman empire,’ in P. L. Cottrell, G. Notaras, G. Tortella (eds), From the Athenian Tetradrachm to the Euro. Studies in European Monetary Integration (Aldershot, 2007), pp. 7-23, at p. 18; S. von Reden, Money in Classical Antiquity (Cambridge, 2010), p. 54; O.D. Hoover, ‘Coins and coinage’, in M. Gagarin (ed.), The Oxford Encyclopedia of Ancient Greece and Rome, Volume 1 (Oxford, 2010), pp. 238-48, at p. 244.

KEVIN BUTCHER and MATTHEW PONTING64

fineness, which was regarded as a sign of poor quality control.3 It looked as if some coins were struck at high fineness and others at low fineness, and at points everywhere in between. The variations were considerable: for example, under Antoninus Pius in AD 157-158, the silver content of the denarius apparently ranged from 71.5% to 93%.4 The average of the widely varying figures for each issue period was taken as a general index of silver content for that period, but in some cases it was almost impossible to suggest a believable average, so erratic were the results.

If a coherent impression can be said to have emerged from the averages presented in Walker’s analyses of second century denarii, it was one of a gradual and incremental deterioration in quality between the reign of Hadrian and the reign of Septimius Severus, rather than maintenance of uniform standards followed by sudden steps down to lower standards. In the second tome of his three-volume study, The Metrology of the Roman Silver Coinage, Walker reported that there was no change in the silver content of the denarius between the debasement under Trajan (which he dated to AD 1075) and a reduction in silver content of the denarius in AD 148, under Antoninus Pius.6 From AD 107 to 148 the denarius averaged between about 87% and 90% fine, but after AD 148 it seemed to average only 82% to 85% fine.7 In his later synthetic study at the end of the third volume of the Metrology, Walker tried to identify an episode of high expenditure that could have triggered the debasement.8 It was surely a sign of severe financial stress that this frugal and conservative emperor had been forced to debase his coinage. Noting that the date coincided with Pius’ decennalia, the games celebrating Rome’s 900th anniversary, and a liberalitas, Walker argued as follows:

If it is the case that the abnormally high expenditure in this period could only be met by debasement of the coinage, then it is an indication of the hand to mouth existence of the Imperial government, even at the period of the highest prosperity of the Empire. It may seem extraordinary, and cannot be said to be proved; but what followed the death of Antoninus Pius tends to suggest that it was indeed the case.

This vision of the High Roman Empire almost permanently on the edge of bankruptcy proved extremely powerful, and the results for the reigns of Marcus Aurelius and Commodus – or at least, the average fineness of the highly variable individual results – were considered to offer further proof of the effect that expenditure had on the silver coinage. From now on, manipulation of the silver coinage became the state’s preferred way of alleviating the mounting pressures of paying for wars

3 R. Duncan-Jones, Money and Government in the Roman Empire (Cambridge, 1994), p. 230. The relevant volumes by D.R. Walker are: The Metrology of the Roman Silver Coinage, Volume II. From Nerva to Commodus (Oxford, 1977) (hereafter Walker 1977); and Volume III. From Pertinax to Uranius Antoninus, (Oxford, 1978) (hereafter Walker 1978).

4 Walker 1977, p. 32.5 Walker 1977, pp. 55-7; 1978, p. 122.6 Walker 1977, p. 57-8, followed by K. Harl, Coinage in the Roman Economy (Baltimore, 1996), p.

94. However, Duncan-Jones regards this period as one of declining quality: op. cit., pp. 224-5. 7 Walker 1977, p. 60.8 Walker 1978, pp. 124-5.


and handouts. Somewhere among the debasements of the second century was the tipping point that led to the third century collapse of the currency.

Walker’s results for individual denarii of Marcus Aurelius appeared even more chaotic than that of Antoninus Pius, so much so that a standard was almost impossible to discern. However, very few of the coins analysed gave figures for silver above 90%, which was taken as a sign that there had been a debasement immediately after the accession of Marcus in AD 161, so that now the spread of individual results tended to fall between about 73% and 89.5%.9 There then seemed to be an improvement between AD 166 and 170, returning to the ‘standard of Antoninus (Pius)’.10 After 170 the averages became erratic again, although they were generally lower than those for the coinages for AD 166-170, suggesting that another debasement had taken place. This was taken as evidence that the strain was increasing, and the cycle of debasements was becoming more frequent as state finances became progressively weaker.11 In particular, the debasement at the accession of Marcus was regarded as evidence that even donatives by new emperors placed a major strain on finances. If this were the case, then the state must have been hovering on the brink of insolvency. Debasement was a way of raising urgently needed revenue. Here, surely, was the beginning of the collapse.12

The averages for each issue of coinage for Commodus appeared to show much less variation than that for Marcus Aurelius, as if the system of variable fineness had been more restricted. For this coinage an even lower overall standard of fineness of between 74% and 77% could be detected. This was introduced in AD 180 at the very beginning of his sole reign.13 Accompanying it was a reduction in the average weight of the denarius. Once again, this debasement on the accession of an emperor was attributed to ‘an acute shortage of cash to pay the necessary donatives’.14 A further debasement in 190, to about 72%-73%, was likewise attributed to excessive expenditure. Then, in AD 193, the year following Commodus’ death, there was a curious reversal of the cycle of debasement when Pertinax appeared to raise the silver content of the denarius to 87%.15 This was seen as a sign of the moral conservatism of the regime. However, the underlying evidence for this improvement is rather weak: the results for the coins of Pertinax ranged from 78% to 94%. Nor was there evidence for the higher fineness persisting, and under Pertinax’s successor, Didius Julianus, the fineness declined, falling to about 78% under Septimius Severus. Finally, the great debasement of AD 194/5 was seen as ‘a return to a more pragmatic and hand to mouth policy than that which Pertinax had briefly attempted to follow’.16

9 Walker 1977, p. 58.10 Walker 1977, p. 58; 1978, p. 126, Harl, op. cit., p. 95.11 Walker 1978, p. 125.12 Focus on Marcus Aurelius as the key instigator of debasement in the second century: Harl, op. cit.,

p. 95: ‘the most serious debasement since the Civil War of 68-69’; Verboven, op. cit. (n. 2), p. 246; B. Hitchner, ‘Coinage and metal supply’, in A. Bowman and A. Wilson (eds), Quantifying the Roman Economy (Oxford, 2009), pp. 281-6, at p. 282; C. Katsari, The Roman Monetary System (Cambridge, 2011), p. 78.

13 Walker 1977, p. 59; Harl, op. cit., p. 126.14 Walker 1978, p. 126.15 Walker 1978, p. 51; pp. 127-9. See also C. Howgego, Ancient History from Coins (London, 1995), p. 119.16 Walker 1978, p. 130.


A complex scheme emerged from the results, employing multiple standards of fineness but fairly consistent averages from AD 107 to 148; followed by continued variation and a lower average standard of fineness to 161. After this, some kind of debasement was thought to have occurred, with issues being struck at widely different average standards, until AD 180. Finally, Commodus struck coins at more consistent standards, and two debasements were detected, one at the beginning of the reign and a second in 190. However, anyone looking at the results for individual coins and standard deviations for issues could see very little convincing structure underlying the averages on which the narrative was based. With such uncertainty it is scarcely any surprise that accounts of Roman currency tend to treat the period with reserve.

Nevertheless, Walker’s discovery that excessive spending was matched by debasement was one of the most influential features of The Metrology of the Roman Silver Coinage.17 As a result, the argument that financial pressures in the Antonine period forced the Roman state to manipulate the coinage now seems uncontroversial, and it is a credit to the strength of the case made by Walker. His results for the second century denarii give the impression that fineness habitually fell at the beginning of reigns, a symptom of financial pressures brought about by the need to make donatives combined with an inadequate supply of silver.18 Wars and other expenditures also contributed to a gradual fall in silver content, leaving one to conclude that the state was unable to balance income against expenditure, and that manipulation of the coinage was preferable to increased taxation.19

Aside from the decline in fineness, there also appeared to be a decline in the weight of the denarius, which further contributed to the falling silver content. This weight change seemed to be particularly apparent for the denarii of Commodus. Using data from hoards, Duncan-Jones argued for continued use of the Neronian weight standard from Trajan to Marcus Aurelius, followed by two stages of reduction under Commodus.20 This impression may be correct, though more studies of the metrology of the denarius are needed. What is not often appreciated is the complex behaviour of the binary silver/copper alloys from which Roman imperial denarii were made, and the role that corrosion has played in reducing the weights of Roman silver coins as we have them today. Those with a higher degree of copper are particularly susceptible. Thus, as the copper content of the denarii increases, the weights of individual denarii become increasingly unreliable as an indication of the original weight, because a proportion of their copper content has been preferentially leached out during centuries of burial, and the process of cleaning after recovery from the

17 See the remarks by Howgego, op. cit., pp. 118-19; Duncan-Jones, op. cit., pp. 238-240; and Katsari, op. cit., p. 78.

18 Howgego, op. cit., p. 119; Harl, op. cit., p. 95.19 The idea of debasement being preferable to taxation was expressed by A.H.M. Jones (see his The

Roman Economy. Studies in Ancient Economic and Administrative History (Oxford, 1974), pp. 189-90), followed by Walker 1978, pp. 109, 111, 125. Despite these arguments, the distinction between debasement and taxation is rather strained, since debasement is a form of increased taxation.

20 Duncan-Jones, op. cit., pp. 225-9.


ground.21 This corrosion is not always apparent from simple visual inspection, and can only be confirmed by microscopic examination of a cut section of each coin.22 Such a method is scarcely practical for large-scale metrological studies, and so we must admit that we do not have particularly reliable data with which to form a precise understanding of the metrology of alloyed denarii. Few of the coins will survive at their original weight. In addition, changes in production technology could also make the finished coins more or less susceptible to corrosion, giving the false impression of a sudden change in weight standard.

The potential extent of the problem can be demonstrated by examining the weights of a random sample of denarii of Commodus that exhibit well-preserved, unworn surfaces. The sample of 56 coins of the period AD 187-192 was taken from the web site of Classical Numismatic Group, Inc., and the coins come for a wide variety of sources. The period 187-192 was deliberately chosen, because it is the period suspected to be the one when the weight of the denarius was at its lowest.23 The average weight, the median value, and the mode for this sample are remarkably consistent, suggesting a target weight of 3.06g-3.07g, which is considerably lower than the weight of earlier denarii (table 1). Currently our data for the metrology of denarii extend no later than Trajan, under whom the average weight is 3.40g, which is almost identical to the value we have obtained for Nero. Duncan-Jones has a very similar figure of 3.36g for Trajan, and he sees this continuing until the end of Marcus Aurelius’ reign. The results tabulated in our table 1 suggest that by the latter part of the reign of Commodus the weight of the denarius had been reduced significantly. However, if one plots the distribution of the weights (fig. 1), the results look very different. The distribution is not at all smooth. There are two peaks: one centred on the 3.30g-3.39g interval, and a larger one centred on 2.90g-3.09g. This could be taken as an indication that two weight standards were in use, and that, by grouping all coins of AD 187-192 together, we have missed an important change in weight. Alternatively, it could be taken to indicate that denarii of AD 187-192 were struck at two different weight standards concurrently. A third possibility is that the coins of AD 187-192 were issued at a single standard of about 3.4g (the same as earlier denarii), and that the underlying metallurgy of the flans tends to result in an average loss of about 0.3g of copper due to corrosion and leaching over time. Given our poor understanding of the metrology of the coinage of this period it would be premature to choose from among the three alternatives posited above, especially when the results derive from a relatively small sample (a fourth interpretation being that the data are simply too few to form a representative sample). A fall in weight under Commodus is entirely possible, but the appearance of a peak of about 3.30g-3.39g in fig. 1,

21 This is neatly demonstrated in Duncan-Jones, op. cit., pp. 242-3, where there is an inverse correlation between weight and fineness of denarii of this period. The explanation for this inverse correlation is clear enough: those with a higher copper content remaining are closer to their original weight; whereas those with a higher silver content have lost more of their copper and consequently lie much further below their original weight.

22 See B.E. Woytek, K. Uhlir, M. Alram, M. Schreiner, M. Griesser, ‘The denarius under Trajan: new metallurgical analyses’, NC 167 (2007), pp. 147-63.

23 Duncan-Jones, op. cit., p. 225, table 15.5.


close to the ‘normal’ weight for denarii, illustrates how careful one needs to be when studying the weights of surviving coins as evidence for changes in standards.

Mean Median Mode Standard deviation3.07g 3.06g 3.06g 0.33

Table 1. Average weight of denarii of Commodus, AD 187-192.

Fig. 1. Distribution plot of weights of denarii of Commodus, AD 187-192.

With so much uncertainty about the weight and fineness of second century denarii, can we really take them as indicators of the underlying financial weakness of the Roman empire at its height? Both sets of data are in urgent need of correction. It has been apparent for some years now that Walker’s data for fineness are faulty, because he failed to appreciate the nature of the binary silver/copper alloys used for Roman silver coinage.24 On the other hand, the role of those alloys in altering weight data is not acknowledged at all. The following results derive from a new set of analyses undertaken by the authors as part of a wider project studying the composition of Roman imperial denarii. It reports on the composition of the coins only. A study of the other key factor in determining silver content, the metrology of the coins, is reserved for a future study. Here we deal only with those denarii of each reign that can be easily dated, so as to form an overview of the chronology of changes in fineness. Many other second century denarii have been analysed for the project, but these are omitted from the discussions below.

24 Walker did not fully appreciate the effects of ‘surface enrichment’ of silver, and did not know that the copper portion of the alloy had been deliberately depleted at the surface of the flans before minting in order to give the impression that the denarii were made of fine silver. He tried to overcome the problem of enrichment by scraping the edges of the coins before sampling, but in most cases he failed to penetrate the deeply enriched surfaces effectively. Our sampling technique involves drilling into the cylindrical edge of the coin, discarding the first millimetre or so of turnings (which contain the enriched surface material) and analysing only the heart metal of the coin, where the effects of copper depletion are at a minimum. On the problems with Walker’s data, see K. Schmitt-Korte and M. Cowell, ‘Nabatean coinage – Part I: the silver content measured by x-ray fluorescence analysis’, NC 149 (1989), pp. 33-58; K. Butcher and M. Ponting, ‘Rome and the East: production of Roman provincial silver coinage for Caesarea in Cappadocia under Vespasian, AD 69-79’, Oxford Journal of Archaeology 14.1 (1995), pp. 63-77; and K. Butcher and M. Ponting, ‘Atomic absorption spectrometry and Roman silver coins’, in A. Oddy and M. Cowell (eds), Metallurgy in Numismatics, Vol. 4 (London 1998), pp. 308-34.


The denarius in the first centuryThe results for the coinages of the first century have been presented elsewhere, but a brief summary is necessary here.25 From Tiberius to Nero the denarius was made of pure silver bullion, although its weight declined during this period. Then, in about AD 64, Nero reduced its weight and issued it at about 80% fine. In AD 68 he raised the silver content to 90%, but continued to use the same reduced weight of about 3.45g. The following year, during his conflict with Vitellius, Otho lowered the fineness back to 80%, where it stayed until AD 82, when Domitian again issued denarii made of pure silver bullion. In AD 85 Domitian reduced it back to the revised Neronian standard of 90%, where it stayed until AD 99. In this year, Trajan lowered the fineness back to the first Neronian standard of 80%. It remained at this fineness for the rest of Trajan’s reign.

Trajan (AD 98-117)An account of the fineness of the denarius coinage of Trajan has been provided by Woytek et al.26 Following the reduction in AD 99, the fineness remained at the first Neronian standard for the rest of the reign. Our results concur with this observation and, in order to illustrate that point, we include the last group of Trajanic denarii here. Five coins of the period AD 116-117 have an average fineness of 80% (fig. 2).

Fig. 2. Dot plot of silver bullion contents of Trajan’s denarii of AD 116-117 and the Rome denarii of Hadrian.

25 K. Butcher and M. Ponting, ‘The Roman denarius under the Julio-Claudian emperors: mints, metallurgy and technology’, Oxford Journal of Archaeology 24.2 (2005), pp. 163-97; ‘The denarius in the first century’, in N. Holmes (ed.), Proceedings of the XIV International Numismatic Congress, Glasgow 2009 (Glasgow, 2011), pp. 557-68.

26 Woytek et al., op. cit.


Hadrian (AD 117-138)The reign of Hadrian is generally regarded as a period without changes to the coinage, with the denarius remaining at the Trajanic standard, or else falling very slightly below it.27 Consequently Hadrian’s reign figures little, if at all, in accounts of the Roman monetary system. This view, which treats Hadrian’s denarius coinage as merely a continuation of the first Neronian standard, appears mistaken. There were changes under Hadrian, but these did not result in decreased fineness by the end of the reign. Instead, the fineness oscillates between the first Neronian standard and a lower fineness of just above 70%.

Group Weight % silver bullion (Ag+Au+Bi+Pb)Mean Standard

DeviationNumber

AD 116-117 (Trajan) 79.6 2.2 5

AD 117 76.3 1.2 2AD 118 71.4 1.8 9Class A 75.4 1.9 16Class B 73.3 2.2 18Class E 76.8 2.4 5Class C 76.0 1.9 3Class D 78.9 1.6 29

Table 2. Silver bullion contents of Hadrian’s Rome denarii and those of the last issue of Trajan.

The chronology of Hadrian’s denarius coinage is difficult to establish because of a lack of diagnostic titulature that would help to divide it into discrete periods. That said, the issues of the first two years, AD 117 and 118, are readily identifiable.

AD 117: IMP CAES TRAIAN HADRIAN(O) OPT AVG GER DAC / PARTHIC DIVI TRAIAN AVG F P M TR P COS P P2 coins analysed

AD 118: IMP CAESAR TRAIAN HADRIANVS AVG / P M TR P COS II 9 coins analysed

It is evident from fig. 2 and table 2 that the issue of AD 117 was close to the standard of Trajan, though possibly a little below it – it is difficult to be certain on the basis of the results for just two specimens. However, the issue of AD 118 was certainly of lower fineness. Hadrian reduced the silver content of the denarius shortly after his accession. If this was the result of financial difficulties early in the reign, the expedient of debasing the coinage may have helped relieve them, because the next issue reverts to a higher standard.28

27 Duncan-Jones, op. cit., pp. 101, 224, 227.28 SHA Hadrian 6.5 on the problems of the aerarium on Hadrian’s accession. Hadrian famously

remitted tax liabilities in AD 117-118: Dio 69.8.1; SHA Hadrian 7.6; Duncan-Jones, op. cit., p. 59; commemorated on coins, RIC II, nos. 590-5. Perhaps the temporary reduction in fineness helped offset the emperor’s generosity?


For the rest of the reign there are very few chronological indicators. Hadrian held his third and last consulship in AD 119, meaning that the frequent use of the iteration COS III is of no help in dating most of his coinage. In AD 128 he adopted the title pater patriae, which appears on coins; presumably all those bearing it belong to the second half of the reign, AD 128-138. The coins, however, exhibit a number of different legends that can be placed in a relative sequence. More refined, absolute dates seem to rest on the assumption that Hadrian’s absence from Italy would have left the legends immobilised and his return from his travels would immediately usher in a change of legend.

Two groups, dubbed classes A and B by Mattingly, lack the title pater patriae, and are dated to AD 119-128. Class A is placed first because the reverse legend appears to be a continuation of the issues of AD 118, with COS III substituted for COS II, and because the obverse legend repeats the form used in AD 118. While there is general agreement that class A begins in AD 119, the date when it ended remains unclear. In RIC II Mattingly preferred AD 122; in BMCRE III he proposed AD 124 or 125.29 Strack preferred AD 123.30 For our purposes the absolute date matters less than the relative chronology of the different classes. Class B has the simple obverse legend HADRIANVS AVGVSTVS. Strack saw in this legend a resonance with the coinage of Augustus and proposed that it began in AD 123, marking the hundred and fiftieth anniversary of Octavian’s adoption of the title Augustus; Mattingly associated it with Hadrian’s return to Rome in AD 125. The issue of class B coins presumably continued until AD 128, when they were replaced by issues bearing the title pater patriae.

CLASS A: IMP CAESAR TRAIAN HADRIANVS AVG / P M TR P COS III (AD 119 – AD 123 or 125)16 coins analysed

CLASS B: HADRIANVS AVGVSTVS / COS III on reverse (AD 123 or 125 – early AD 12818 coins analysed

The class A coins are on the same standard of fineness as the coins of AD 117. Whatever had caused the debasement of AD 118, the following year the debasement was abandoned. However, the class B coinage, with the obverse legend HADRIANVS AVGVSTVS, appears to have reverted to a slightly lower fineness that resembles the one employed in AD 118.

The remaining classes of coin all bear the title pater patriae, and must belong to AD128 or after. The first of these is thought to be Mattingly’s class E, which he originally assigned to a later period, suggesting they were posthumous issues struck under Antoninus Pius. But hoard evidence indicates that class E is earlier, and follows class B.31 The end date of the issue seems far from certain; the date of

29 BMCRE III, pp. cxv-cxvi.30 P.L. Strack, Untersuchungen zur Römischen Reichsprägung des zweiten Jahrhunderts, Teil II. Die

Reichsprägung zur Zeit des Hadrian (Stuttgart, 1933).31 See comments in BMCRE III, pp. cxvi-cxvii.


AD 132 assigned by Mattingly, marking Hadrian’s return from his second round of travels, seems somewhat arbitrary; Strack preferred a much shorter window of issue, AD 128-129. This class was followed by the classes C and D coinage. Mattingly assigned class C to AD 132 – 134/5 (the latter date marking another return of Hadrian) and D to AD 134/5 – 138, whereas Strack proposed that class D came first, AD 130-138, and was accompanied in its later phase by class C (dated AD 134-138).

CLASS E: HADRIANVS AVGVSTVS P P / COS III5 coins analysed

CLASS C: HADRIANVS AVGVSTVS / COS III P P or P P COS III3 coins analysed

CLASS D: with obverses reading HADRIANVS AVG COS III P P29 coins analysed

All coins marked with the title pater patriae are on or close to the first Neronian standard. It would appear that Hadrian reverted to this level of fineness for the last decade of his reign.

To summarise: Hadrian’s first issues appear to be on the same standard as Trajan’s coinage, or very slightly lower. In AD 118 the coinage was debased, but in 119 it returned to a higher standard. It remained at this level of fineness for about four years, and then for about six years reverted to the lower standard. In AD 128 the fineness was raised, and returned to the level it had held under Trajan. Far from being uniform and devoid of interest, silver standards under Hadrian show some interesting changes.

However, it should be stressed that the debasements under Hadrian were relatively minor, no more than 6%-7%, and they would have been extremely difficult for the public to detect, particularly given the fact that individual coins on the different standards overlap to some degree and that old and new issues of denarii circulated together. While the debasements could point to financial difficulties, the fact that the debasements were minor and relatively short-lived could indicate no more than an occasional desire to squeeze a little more profit out of the coinage.

Antoninus Pius (AD 138-161)The coinage of Antoninus Pius can be fairly closely dated, especially after AD 146/7, when most of the denarii begin to bear dates according to Antoninus’ tribunician power. This enables us to date any changes very accurately.

As noted above, Walker detected a debasement in AD 148. However, our results show no change in that year (fig. 3 and table 3). From his accession (AD 138) to the issues of TR P XIX (AD 155-156) the coinage of Antoninus Pius was issued on the first Neronian standard of fineness, the same as Trajan’s denarii from AD 99-117, and Hadrian’s denarii from 128-138.


Fig. 3. Dot plot of the silver bullion contents of the Rome denarii of Antoninus Pius.

Date Weight % silver bullion (Ag+Au+Bi+Pb)Mean Standard

DeviationNumber

138 78.2 1.0 4139 81.0 5.3 7140-143 78.6 3.2 9143-144 77.5 1.3 4144 77.8 3.1 3147-148 76.7 3.3 3148-149 78.5 2.4 12149-150 78.7 2.0 2150-151 78.1 2.6 4151-152 76.8 1.0 6152-153 77.3 1.3 10153-154 74.5 6.8 10154-155 77.8 4.0 9155-156 74.9 4.4 19156-157 70.9 1.8 18157-158 71.2 2.6 16158-159 70.3 6.6 9159-160 72.7 2.3 4160-161 70.0 1.6 3

Table 3. Silver bullion contents of the Rome denarii of Antoninus Pius


In AD 155-156 the fineness decreased to about 74%, and in the following year, 156-157, to 70%, where it stayed for the rest of the reign.32 It therefore looks as if this debasement proceeded in two stages, with an initial reduction in 155-6, and a second in 156-7. The debasement of 155-157 is much more significant than the temporary ones under Hadrian, and set the standard for the coinages that followed.

Marcus Aurelius (AD 161-180)The denarii of Marcus Aurelius were struck at the same standard as Antoninus Pius for most of the reign (fig. 4 and table 4). There are hints that there may have been an attempt to return to the first Neronian standard between about AD 164 and 166, but the number of specimens analysed is quite small and it would be useful to have more samples in order to confirm this impression. There is no indication of a ‘dramatic’ debasement at the beginning of the reign,33 nor any indication of financial troubles c. AD 169-170.34 The tight cluster at about 67% fine in Marcus’ final year may indicate a very slight decline (or poor control of the standard), but this decline cannot have endured since it is not very evident in the succeeding coinage of Commodus.

Fig. 4. Dot-plot of silver bullion contents of the Rome denarii of Marcus Aurelius.

32 The average fineness of 74.9% for AD 155-156 is caused by one anomalously high reading, no doubt caused by a coin that had suffered severe depletion of copper at its core. When this is removed, the average fineness is 73.9% and the standard deviation drops from 4.4% to 1.1%. Note also two coins, both from the Shapwick hoard, that have low finenesses (both under 60%) and span the debasement of AD 155-6. These are presumably irregular issues.

33 So Walker 1977, p. 58.34 Walker 1978, p. 126.



DeviationNumber

161 68.4 1.1 3161-162 69.2 1.4 4162-163 68.8 2.6 4163-164 71.1 1.9 7164-165 76.9 5.1 2165 82.1 6.8 3165-166 76.9 1.8 3166 75.5 1.9 2166-167 74.7 4.3 4167-168 70.4 . 1167-178 71.6 . 1168 74.1 .8 3168-169 72.4 3.7 2169-170 70.7 .2 2170-171 71.1 3.3 2171-172 70.2 1.2 2172-173 70.7 3.5 2173-174 71.9 1.6 2174 71.1 . 1174-175 72.0 . 1175 78.8 4.6 2175-176 75.0 6.5 3176-177 74.1 8.2 4177 72.7 . 1177-178 80.2 14.4 2178-179 66.6 .8 4

Table 4. Silver bullion contents of the Rome denarii of Marcus Aurelius.

Commodus (AD 180-192)There is very little variation in the coinage of Commodus (fig. 5 and table 5).35 The averages are very slightly reduced from the averages found under Antoninus Pius after AD 156-157, but one should not take the difference as particularly significant, because the majority of coins fall in the same range as the later coins of Antoninus Pius and those of Marcus Aurelius. If a reduction in fineness occurred under Commodus, it was in the order of 2%. The weight reduction, assuming that it did indeed occur (see above), was more significant. The only noticeable difference is at the end of the reign, in the coinage of AD 192, where two denarii fall significantly below the normal standard. This is perhaps a sign of poor control of the established standard rather than a fall in overall fineness.

35 Two coins of Commodus, both from the Shapwick hoard, have very low finenesses of less than 50% and are presumably irregular.


Fig. 5. Dot-plot showing the silver bullion contents of the Rome denarii of Commodus


DeviationNumber

180 67.1 . 1181 69.3 1.8 4181-182 69.7 1.5 6183 67.5 1.4 4183-184 66.8 .8 3184 65.7 . 1184-185 66.8 3.3 4186 72.0 7.4 8186-187 69.9 4.4 6187-188 65.6 10.3 7188-189 65.2 9.4 7189 70.3 2.9 6190 68.7 2.0 5190-191 67.8 2.5 9191 63.4 . 1192 65.2 5.6 10

Table 5. Silver bullion contents of the denarii of Commodus

Pertinax (AD 193)The denarii of Pertinax appear to be on the same standard of fineness as those of Commodus (average 68%, with a standard deviation of 6%, for seven coins). Two further coins of Pertinax, omitted from the calculations, measure 80% and


91% respectively. Should this be regarded as evidence that Pertinax improved the coinage? It seems unlikely. The two coins, both specimens of RIC 13, come from museum collections. In one case we know that the coin is likely to have been harshly cleaned at some point in the past, stripping it of its copper content and artificially raising its silver content, because other coins in the same collection exhibit the same tendency for anomalously high silver readings. A similar case may be posited for the other specimen, which is also from an old collection. Two further specimens of RIC 13 from the Shapwick hoard both have a fineness of 66%, comparable to other denarii of Pertinax. It seems highly unlikely that the same type would have been issued at two or even three different standards of fineness. The ‘reform’ of Pertinax can be safely dismissed as a phantom.

Didius Julianus (AD 193)The fineness of denarii of Didius Julianus shows no change from those of Commodus or Pertinax (average 68%, with a standard deviation of 3.5%, for five coins).

Septimius Severus (AD 193-211)An important debasement took place in the early years of Septimius Severus. In their monograph on the coinage of Septimius Severus, Gitler and Ponting analysed two denarii of Rome issued prior to the debasement in c. AD 194. These show that the fineness remained the same as it had been under the previous rulers.36 Afterwards the denarius was reduced in fineness to about 46%.37

The debasement of AD 194 marks the end of this survey of fineness, and marks a decisive move away from the Neronian standards of purity. It seems, however, that Severus retained the Neronian weight standard, which implies an attempt to create a sense of continuity with the earlier coinages, despite the change in silver content.38 And, as we noted in our 1997 paper, the coinage produced by Clodius Albinus in Gaul in c.195-197 was issued at the first Neronian standard of fineness (80%).39 These post-194 coinages, however, lie outside the scope of the present paper.

Minor and trace elementsThe two trace elements most strongly associated with the source of the silver, gold and bismuth, exhibit a gradual yet significant change over time. The denarii of Hadrian mostly form a tight group characterised by low gold (<0.25% scaled to silver) and low bismuth (<0.25% scaled to silver; fig. 6a), and these are quite different from the denarii of Trajan, whose coinage has a gold/bismuth pattern that more closely resembles that of the period from Nero’s reform to Nerva. The low gold and low bismuth signature of most of Hadrian’s denarii is unusual and not commonly encountered in earlier denarii, being limited to the issues of Tiberius, Caligula and Claudius. It appears again, briefly, under Domitian, but does not occur under Nerva or Trajan.40 This may represent either the use of a previously untapped

36 H. Gitler, M. Ponting, The Silver Coinage of Septimius Severus and his Family (193-211 AD) (Milan, 2003), pp. 55 and 63-64, nos 1 (69.5%) and 7 (68.4%).

37 Gitler and Ponting, op. cit.; K. Butcher, M. Ponting, ‘A study of the chemical composition of Roman silver coinage, AD 196-197’, AJN 9 (1997), pp. 17-36.

38 Duncan-Jones, op. cit., p. 222.39 Butcher and Ponting, op. cit. (n. 37).40 Butcher and Ponting, The Metallurgy of Roman Silver Coinage, forthcoming.


silver source or the heavy recycling of specific earlier issues. Note that there is also a small group of high gold/low bismuth coins of Hadrian in fig. 6a that probably represents recycled Neronian/Flavian denarii, since these issues have identical gold and bismuth contents.


Figs 6a-c. Scatterplots for gold and bismuth scaled to silver for Antonine denarii

During the reigns of Antoninus Pius and Marcus Aurelius the composition changes, with a slight increase in the gold content and a larger increase in the bismuth content (up to 1%, fig. 6b). This metal remains quite different from that used for earlier denarii; the gold content remains lower than the 0.5 to 1% usually encountered in denarii issued in the first century, and the bismuth content continues to increase, now well above the 0.1% upper limit that characterised the earlier coinages.41

The same trends continue into the reign of Commodus, with bismuth contents reaching 2% (fig. 6c). Gold contents only occasionally reach Julio-Claudian or Flavian levels, where they no doubt represent the occasional recycling of the earlier coins, probably of the period from Nero to Trajan.

Such a shift in the gold and bismuth contents must mean a shift in silver source or sources.42 If Hadrian’s denarii were made of metal from a particular source, as might be inferred from the tight group that the coins form, then the gradually increasing bismuth (and, to a lesser extent, gold) contents seen in the denarii of Antoninus Pius and Marcus Aurelius may suggest the dilution of this metal with silver containing higher levels of bismuth and gold. The increase in gold could easily be accounted for by the addition of recycled earlier coin, while the higher bismuth must indicate the inclusion of a further source not previously tapped.

41 Butcher and Ponting, The Metallurgy of Roman Silver Coinage, forthcoming.42 For an overview of the use of gold and bismuth contents see M. Ponting, ‘The substance of coinage’,

in W. Metcalf (ed.) The Oxford Handbook of Greek and Roman Coinage (Oxford, 2011), pp. 12-30.


Obviously some of the trace elements measured in alloys of silver and copper will have come into the alloy with the copper rather than the silver. Generally, it is assumed that gold, bismuth and lead relate to the silver, while elements such as arsenic, nickel, antimony, cobalt, iron, manganese, tin, zinc and chromium will have originated in the copper. There are some exceptions, of course, such as the significant levels of nickel and cobalt found in some native silver or rich-ore sources,43 which urge caution in applying this assumption without close scrutiny. A principal components analysis (PCA) of these copper-related elements indicated a great homogeneity of composition across most of the denarii analysed. The denarii of Commodus and some of the denarii of Marcus Aurelius, however, cluster towards one corner of the plot characterised by increased levels of arsenic, antimony and manganese. A scatterplot of the arsenic and manganese contents (fig. 7) clearly shows how the denarii of Commodus stand out due to their higher antimony and manganese levels. Some denarii of Marcus Aurelius also have high manganese.

Manganese is a frequent component of copper ores, but does not usually pass through the smelting system into the copper metal, remaining behind to help form the slag.44 Thus it is most likely that the enhanced levels of manganese in Commodus’ denarii come from the silver rather than the copper. Indeed, manganese has an unusually high level of solubility in silver and would tend to partition towards the silver in a high temperature system.45

Fig. 7. Scatterplot of antimony against manganese for Antonine denarii.

43 J. Dayton, The Discovery of Glass: Experiments in the Smelting of Rich, Dry Silver Ores, and the Reproduction of Bronze Age-type Cobalt Blue Glass as a Slag (Cambridge, MA, 1993).

44 P. Craddock, Early Metal Mining and Production, Edinburgh, 1995, p. 200.45 A. Butts and C. Coxe, Silver: Economics, Metallurgy and Use (Princeton, 1967), p. 260.


Thus some denarii of Marcus Aurelius and most denarii of Commodus were produced from silver that is different not only in having high levels of bismuth, but also in having high levels of manganese. The origin of such a composition is most probably the source of the silver, but tracing such a source is highly problematic. There is archaeological evidence that indicates a relocation of imperial silver mining interests from the western provinces to south central Europe during the second century, notably deposits in what is now the central Balkans. Recent survey and excavation has revealed extensive lead/silver mines in the Mount Kosmaj region of Serbia46 and silver/gold mines in the Rosia Montana region of Romania.47 At Rosia Montana, ores containing electrum of varying composition mean that both gold and silver would have been produced, necessitating the separation of the gold from the silver by the ‘parting’ process,48 followed by the mixing of the silver-rich waste with lead, and the extraction of the silver by cupellation.49 An analysis of the ores at Rosia Montana shows that they are characterised by the presence of manganese and antimony minerals.50 Whether this indicates the source of the silver used for later Antonine denarii will require further work, but these results clearly suggest that it is a distinct possibility.

ConclusionsIt is hard to see any evidence of pressure on the denarius due to specific episodes of expenditure during this period. The debasement at the beginning of the reign of Marcus Aurelius, signposted by Walker as the beginning of the decline of the Roman empire, appears to be a ghost, formed by the somewhat random nature of his erratic analytical results.51 Nor did the presumed debasement later in his reign occur in reality; and if debasements occurred under Commodus, they took the form of weight reductions, but even these need to be verified.

The pivotal point of the period is the debasement of AD 155-157 under Antoninus Pius, when the fineness was reduced, in two steps, from about 78%-80% (the first Neronian standard) to about 70%. There is evidence of Hadrian experimenting with reduced standards in AD 118, and again between c. AD 123/5 and AD 128, which some may wish to view as evidence of financial pressures, but in both cases the debasements were reversed, and from AD 128 to 155-156 the denarius was stable at the first Neronian standard. There is also evidence after the debasement

46 J. Merkel, ‘Imperial Roman production of lead and silver in the northern part of Upper Moesia (Mt. Kosmaj area)’ Journal of the Serbian Archaeological Society 23 (2007), pp. 39-78.

47 S. Baron, C. Tamas, B. Cauuet, and M. Munoz, ‘Lead isotope analysis of gold-silver ores from Rosia Montana (Romania): a first step of a metal provenance study of Roman mining activity in Alburnus Maior (Roman Dacia)’, Journal of Archaeological Science 38 (2011), pp. 1090-1100.

48 Craddock, op. cit., pp. 116-19.49 Ibid., pp. 221-31.50 D. Stan, B. Constantinescu, C. Pauna, A. Vasilescu, F. Constantin, Gh. Popescu, and A. Neasucu,

‘Some applications of x-ray based elemental analysis methods for Romanian gold mineral studies’, Proceedings of the 7th Conference on Nuclear and Particle Physics, 11-15 Nov. 2009, Sharm El-Sheikh, Egypt, pp. 635-43.

51 Walker 1978, p. 125: ‘If a date must be given for the beginning of the decline of the Roman Empire then it should not be that of the death of Marcus Aurelius but his accession.’ Of all the debasements detected by Walker, this phantom one is most often cited in accounts of monetary change during the second century (above, n. 12).


of AD 155-157 of a possible, very slight decline under Commodus, perhaps due to lax standards at the mint more than financial woes, but otherwise the period 156-157 to 194 is one of extreme stability. There may have been an attempt to revert to the first Neronian standard of fineness in AD 165-166 under Marcus Aurelius, as there certainly was under Clodius Albinus in 195-197, but there was no improvement under Pertinax in AD 193. Such improvements in fineness had been a feature of the first century, when Nero and Domitian both reversed earlier debasements, possibly in response to public dissatisfaction with the debased coins. The oscillations under Hadrian may represent a similar phenomenon. The rarity of reversals after 155-157 could be seen as evidence for continued financial pressure or a scarcity of silver. On the other hand, it could also be viewed as evidence that the debasement under Antoninus Pius did not lead to widespread public dissatisfaction or monetary instability (such as widespread hoarding of earlier, ‘better’ coin, or its export outside the empire), meaning that a correction was not necessary.

The debasement of AD 155-157 established a new standard of fineness for the denarius, which persisted for nearly forty years. It was the first notable departure from the standard introduced by Nero in c. AD 64, though it was not as bold as that introduced under Septimius Severus. The date, AD 155-157, does not coincide with any of Antoninus’ many liberalitates (liberalitas VII fell between 151/2-153/4 and VIII in 157/852), which Walker regarded as the sort of excessive expenditure likely to induce debasement.53 The reduction does coincide broadly with a revolt in northern Dacia and problems in Britain and perhaps Judaea, but disturbances in the provinces were hardly infrequent and attributing the change to expenditure on any of these conflicts seems capricious. In fact, we would question whether excessive expenditure has any role to play in explaining this debasement. Previously, it was possible to treat the debasement under Antoninus Pius (wrongly dated to AD 148) as the first episode in a vicious cycle of over-expenditure followed by coinage manipulation to compensate for supposed fiscal inadequacy. That is no longer possible. Now that the debasements accompanying the accession donatives of Marcus Aurelius and Commodus have been shown to be phantoms, the most convincing link between debasement and specific episodes of expenditure has been broken. The context of Antoninus Pius’ debasement is a period of considerable stability, not one of rapid cycles of debasement imagined by Walker. If a fiscal motive is to be discerned, perhaps it should be seen as one of Antoninus’ economies that allowed him to bequeath a treasury surplus to his successors, and a proactive measure designed to increase income without substantially altering silver content, rather than a reactive measure responding to immediate financial hardship.54

Furthermore, if the Roman empire was running short of new sources of silver, we might have expected the trace element data to highlight evidence of increased use of earlier denarii and other materials as a resource. While earlier denarii are likely to

52 BMCRE IV, pp. xlvi-xlvii.53 Walker 1978, p. 124.54 Dio 74.8, where a sum equivalent to 675 million denarii is mentioned. This is in contrast to a sum

equivalent to 250,000 denarii left by Commodus.


have been responsible for some of the points we find at the peripheries of our plots, they do not appear to have been used for the bulk of the coinage. Instead we find evidence for the exploitation of other sources, apparently distinct and discrete, which do not produce the sort of pattern we would expect for a coinage produced from heavily recycled materials. Far from running out of silver, it looks as if the Romans had discovered new sources of supply in the second century, which proved adequate for the huge coinages of the period. Whether these were sustainable in the longer term is another matter, and perhaps data for third century denarii will reveal the onset of a silver shortage. For the time being, however, the supposed link between second century debasement and scarcity of metal does not look particularly viable.

The picture that emerges from our new analyses for the second century bears superficial comparison with that of Walker, inasmuch as there is a difference between the fineness of the denarius under Trajan and its fineness at the start of Septimius Severus’ reign, and it may be thought that these new results do not thereby alter his overall account of the decline of the denarius. In its crucial details, however, it is quite different. No debasements occurred at the beginning of the reigns of either Marcus or Commodus, and consequently there is no clear case to be made for a causative link between donatives on the one hand and reductions in silver content on the other. Continuous decline from one reign to another is replaced by general stability. There were essentially two main standards used in the period from Trajan to Septimius Severus, divided by the debasement under Antoninus Pius. The motivation for the debasement of AD 155-157 is unclear, but it does not have the hallmarks of the first stage in the slide towards disaster that has been attributed to second century debasements, and the pace of debasements did not accelerate afterwards. If a case is to be made for the finances of the High Roman Empire suffering a hand to mouth existence, it will require evidence independent of the coinage.

The Denarius in the Second Century - Royal Numismatic Society

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