Dupondius

Moneta Historical Research by Tom Schroer

The "dupondius", like most other Roman Imperial bronzes of the first three centuries AD, had its origin in the Roman Republican coinage system. The first Roman bronze coins (aes grave) were produced in the early third century BC at weights literally corresponding to the Roman weight system, from the "as" (Roman pound of about 327.45 grams) to the semuncia (half-ounce of 13.6 grams). In the second half of the third century BC, multiples of the "as" began to be struck, among them the dupondius, or double "as". The word "dupondius" is derived from the Latin "duo pondo" which literally means two pounds.

The very first dupondii (pl.) were issued at about 600 grams and bore the mark of value "II" on both sides. The "I" was the mark of value of the "as", and hence the dupondius was marked as a "two-as" piece.  Shortly thereafter the bronze began a steep decline in weight, but no dupondii were issued after about the middle of the second century BC until the moneyer C. Clodius revived them about 45 BC on behalf of Julius Caesar. By that time the "semuncial" weight standard had been imposed by the "lex Plautia Papiria" of 90 BC which fixed the weight of the "as" to one-half of an uncia, or about 13.6 grams, with the other denominations ratioed to that. Hence the revived dupondius was theoretically to be struck at about 27 grams of copper, but in practice it was struck at only about half of that since it was made of orichalcum instead of copper. Mark Antony also struck dupondii from about 37 BC.

When Augustus struck the dupondius he continued with orichalcum, producing dupondii at between 10.5 and 13.5 grams. The only difference between the "as" and dupondius under Augustus was the metal (the "as" was copper), since they were of approximately the same weight and both displayed either bare or laureate busts. The radiate bust which has come to be associated with a "double" denomination was not in fact introduced until late in Nero's reign, and even then its use was not exclusive. Galba and Vitellius ignored the radiate bust type and issued dupondii with either bare or laureate busts. Not until the reign of Vespasian did the radiate bust become dominant on dupondii, and soon thereafter it became the rule.

The weight of the dupondius did not vary greatly for the nearly three centuries in which it formed part of the coinage of Imperial Rome. For most of its existence the weight was between 10.5 and 13.5 grams, and its diameter about 26 to 30 millimeters. As stated above, it was composed of orichalcum, a brass alloy which in the first century was comprised of about 80% copper and 20% zinc. In the second century the alloy was still about 80% copper, but the zinc content fell to only about 5%, with the rest being composed of tin and lead.  The last known dupondii were struck under Probus (270-276), and like all other early Roman Imperial bronzes they were virtually driven out of circulation shortly after the middle of the third century by the nearly total debasement of the antoninianus, which was tariffed at two denarii, as opposed to the 8 denarii which were the equal of the dupondius.

The dupondius is sometimes referred to in older literature as a "second bronze", while its orichalcum double, the sestertius, is referred to as a "first bronze".


Dictionary of Roman Coins


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DUPONDIUS, a weight of two pounds; -- also a piece of Roman money, valued at two asses, and which preserved the same name, notwithstanding the diminution of the as, which was reduced below the pound. -- See AS and its parts.


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