Fig. 1 This denarius of Augustus is about 98% pure silver
Fig. 2 This denarius of Claudius is also about 98% pure silver
For the first ninety years of the Roman Empire, when members of the Julio-Claudian family reigned, the purity of Rome's silver coinage was unassailable: a solid 98% pure or higher. That standard was maintained by the emperors Augustus, Tiberius (14 to 37), Caligula (37 to 41) and Claudius (41 to 54), and even Nero (54 to 68), who didn't change it for the first decade of his reign. (Fig. 1, Fig. 2)
However, the great fire in Rome in 64 marked the start of a debasement that would require about two centuries to unfold, eventually bringing Rome's silver coinage to an unfathomable low.
The cost of rebuilding the razed areas of the capital was extraordinary. Nero chose the quickest and most efficient pathway to raising funds - re-coining old money into new money of lesser intrinsic value, with Nero's treasury pocketing the difference.
At the Rome mint, he decreased the purity of silver denarii by 5%, dropping it from about 98% to about 93%. (Fig. 3, Fig. 4) Simultaneously, he reduced the weight of the denarius by about 12.5%, which further reduced the actual silver weight of the coin.
Fig. 3 A pre-reform denarius of Nero, about 98% pure silver
Fig. 4 A post-reform denarius of Nero, about 93% pure silver
Nero also reduced the weight of his gold aurei, and was even more aggressive in his intrinsic reductions of two major provincial coinages, the silver tetradrachms of Antioch and the billon tetradrachms of Alexandria.
Nero was overthrown in 68, giving rise to a terrifying civil war that raged into 69, the infamous 'year of four emperors'. In the aftermath of the war, a new emperor, Vespasian (69 to 79), came to power. Not surprisingly, there was a catastrophic need for funds, so he reduced the purity of the denarius further still, from Nero's post-reform 93% to about 89%. (Fig. 5)
Fig. 5 A Vespasian denarius, perhaps 89% pure silver
The denarius remained at about 89% pure (though sometimes it dipped to as low as 80%) until the year 82, when Vespasian's second son, Domitian (81 to 96) was emperor. He took the bold measure of restoring the purity of the denarius to the lofty Augustan standard of about 98%. (Fig. 6)
Fig. 6 A denarius of Domitian issued in 84, during the brief high-purity period
This was a fortunate circumstance, but did not last long: just three years later, in 85, Domitian dropped the purity the denarius down to Nero's post-reform standard of about 93%, where it more or less remained for more than twenty years.
Then, in 107 the emperor Trajan (98 to 117) reduced the purity of the denarius by a further 3 or 4 percent, bring it down to 89% to 90% silver. From there the purity slid gently until 148, when the emperor Antoninus Pius (138 to 161) removed about another 5%, bringing the denarius to about 84% or 83% pure. (Fig. 7)
Fig. 7 This Antoninus Pius denarius is perhaps 84% or 83% pure silver
From there, the denarius continued its gentle slide, reaching a low-ebb of about 71% near the end of the troubled reign of Commodus (177 to 192). After that emperor's murder on New Year's Eve of 192, the denarius made a slight recovery under Pertinax and Didius Julianus, two emperors who ruled very briefly in 193 during the civil war that followed.
Before that chaotic year had ended, control in Rome was taken by the frontier general Septimius Severus (193 to 211). Under his otherwise-successful watch, the purity of the denarius dropped to about 57%. (Fig. 8)
Fig. 8 This denarius of Septimius Severus is just slightly more than half silver
Equally damaging to the long-term health of Rome's silver coinage was the introduction in late 214 or in 215 of the double-denarius (commonly called an 'antoninianus'. Fig. 9, Fig. 10) by Severus' eldest son, the emperor Caracalla (198 to 217).
Fig. 9 Caracalla denarius struck in 215
Fig. 10 Caracalla double-denarius, also struck in 215
Though apparently tariffed at twice the value of a denarius, the double-denarius only weighed about 1.5 times more than a denarius. This made it an inflationary instrument by nature, for it had less than 70% of the silver contained in two denarius coins that theoretically had the same circulation value.
The double-denarius and denarius were struck concurrently up through 219, after which the double-denarius was abandoned until the civil war of 238. Thereafter, the double-denarius was struck regularly until it ended up supplanting the denarius late in the reign of Gordian III (238 to 244). (Fig. 11, Fig. 12) From that point onward, silver denarii were rarely produced, and then only as ceremonial coins.
Fig. 11 Gordian III denarius struck in 241
Fig. 12 Gordian III double-denarius of 241
To complicate matters in the study of debasement, there often were differences in purity from one mint to another. For example, in the period 242 to 244, Gordian III's mint at Rome was striking double-denarii that were about 37% pure, whereas at his mint in Antioch was striking them at an average silver fineness of 43.5%.
Over the next four decades, the purity of imperial silver coinage continued to slide, dropping steadily until it had reached about 41% purity under Trajan Decius (249 to 251). Soon afterward, under Trebonianus Gallus (251 to 253) and Aemilian (253), it sank to about 35% pure. (Fig. 13)
 |
Fig. 13 This Aemilian double-denarius, struck in 253, is seemingly is about 35% pure
The slide picked up momentum as Rome's economic and military fortunes faded dramatically under the co-emperors Valerian I (253 to 260) and his son Gallienus (253 to 268). By the tragic year of 260, when Valerian I was captured by the Persians, the purity of the double-denarius had fallen to as low as 15%.
However, the worst was yet to come. As crises erupted on all fronts, Gallienus struggled to keep his empire intact. By the time he was murdered in a coup in 268, the double-denarius had slid to a silver content of 5% or less in some cases dropping to about 2.5%. (Fig. 14)
Fig. 14 This double-denarius of Gallienus, struck in 267 or 268, may contain only about 2.5% silver
As we've seen, the saga of Roman Imperial silver from 27 B.C. to A.D. 268 was one of a steady, inexorable decline. In part two of this study which will appear next month, we'll examine what happened to silver coins during the remaining 200+ years of the Roman Empire.
