Uncia (coin) - Definition and Overview

The uncia (Latin ounce, plural unciae) was an ancient Roman bronze coin valued at one-twelfth of an as produced during the Roman Republic. The uncia had a theoretical weight of about 27 grams under the libral standard and was produced occasionally towards the beginning of Roman cast bronze coinage. Obverse types of the uncia include a knucklebone (ca. 289-245 BC), a barleycorn (ca. 280-245 BC), and the helmeted bust of Roma (from ca. 240 BC).

In the imperial times the uncia was briefly revived by Trajan (98-117) and Hadrian (117-138). The coin was about 11-14 mm in diameter and weighed about 0.8-1.2 grams. It featured the bust of the emperor on the obverse with no inscription and "SC" (Senatus Consulto) in a wreath on the reverse. If this issue belonged to the imperial system, meaning it was not a provincial piece, it would be an uncia. This issue may have been made only for circulation in the East.

See also: Roman currency, Roman Republican coinage.