Augustus (27 BC-AD 14) based the coinage on the aureus
of 1/42 of a pound of gold, equivalent to 25 denarii,
each of 1/84 of a pound of silver, the metals being
struck almost pure. The denarius was valued at 16 asses.
Token coinage consisted henceforth of brass sesterces and
dupondii (equal to four and two asses, respectively),
with copper asses, halves, and quarters, the as being the
most common. Nero in AD 64 lightened aureus and denarius
to 1/45 and 1/96, respectively, but debasement of silver
subsequently took place. Under Septimius Severus it
reached 40 percent, and Caracalla issued a debased double
denarius of the weight of only 1 1/2 denarii. Gallienus'
double denarius of copper and silver, leached to give a
more silver-rich surface, marked a monetary breakdown,
only partially cured when Diocletian and Constantine
again made gold the firm basis for supplementary pure
silver and abundant copper coinage.
Augustus' earliest gold and silver were coined chiefly
in the east - e.g., at Ephesus and Pergamum - and more
briefly at Emerita in Spain. Bronze also was mainly
eastern, though some was struck at Nemausus (Nîmes). The
Rome mint was reopened c. 20 BC for gold and silver and
remained open for this purpose until c. 12 BC; its bronze
continued irregularly. From 12 BC, Lugdunum (Lyon), with
other mints of uncertain identity, undertook the main
western coinages in gold, silver, and bronze. After 64
Rome was once more the chief mint for all metals.
Official mintages were supplemented by a mass of regional
or local coinages, while official coinages from eastern
mints provided necessary currency for local Roman
The bronze of Rome was marked S(enatus) C(onsulto) and
continued to bear the names of the tresviri
monetales - masters of the mint, now reduced to their
traditional number - until
4 BC. But S C also appeared on bronze from Lyon and
Antioch in imperial provinces, showing that whatever
nominal senatorial rights of coinage still lingered
on - the
tresviri are known until the 3rd century - the emperor
wielded effective control over all metals everywhere.
This was logical, since his economic powers were equally
comprehensive. In fact, the old senatorial mint was
transferred from the temple of Juno Moneta on Rome's
Capitoline Hill and merged, probably after the fire of 64,
with an imperial mint for gold and silver elsewhere in
the capital. Henceforth, it worked in sections - six were
normal later - controlled immediately by an imperial
procurator and staffed by slaves or freedmen.