Uncia (coin)

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.