For nearly five hundred years after the foundation of the city the Romans coined no metal except copper. If any gold or silver pieces were in circulation, they must have been of foreign stamp.
The ordinary copper coins of the Republic were six in number, each being distinguished by a particular device, which is preserved with almost perfect uniformity. The names of these coins were:
on the obverse a head of
1. As Janus
2. Semis, the half As Jupiter
3. Triens, one third of the As Minerva
4. Quadrans, quarter As Hercules
5. Sextans, the half Triens Mercury
6. Uncia, one twelfth of the As Minerva
The device on the reverse is the same in all, being a rude representation of the prow of a ship. On the As we find the numeral I, on the Semis the letter S, while on the rest round dots indicate the number of Unciae; thus the Triens is marked oooo, the Quadrans ooo, the Sextans oo, and the Uncia o.
Many of them have the word ROMA, and it gradually became common for the magistrate under whose inspection they were struck to add his name.
According to Pliny, silver was first coined at Rome in 269 B.C., five years before the commencement of the Punic War, in pieces of three denominations:
1. The Denarius, equivalent to 10 Asses.
2. The Quinarius 5 Asses.
3. The Sestertius 2 1/2 Asses.
But when the weight of the As was reduced in 217 B.C. to one ounce, it was ordained at the same time that
The Denarius should be equivalent to 16 Asses
The Quinarius 8 Asses
The Sestertius 4 Asses
and this relation subsisted ever after between the silver coins bearing the above names and the As.
The Denarius and the Quinarius continued to be the ordinary silver currency down to the age of Septimius Severus and his sons, by whom pieces composed of a base alloy were introduced, and for several reigns entirely superseded the pure metal.
Pliny asserts that gold was first coined in 207 B.C., and a few pieces are still extant which correspond with his description, but they are now generally regarded as having been struck in Magna Graecia. The number of Gold coins, undoubtedly Roman, belonging to the Republican period is so small that the best numismatists are of the opinion that this metal did not form part of the ordinary and regular currency until the age of Julius Caesar, the want having been supplied by Greek Philippi. The principal gold coin of the empire was the Denarius Aureus, which is generally termed simply Aureus, but by Pliny uniformly Denarius. The Denarius Aureus always passed for 25 silver Denarii. Half Aurei were also minted, but these are comparatively rare.
unit name metric grams oz. grams
1 Uncia 27.288 0 430.83
1 1/2 Sesuncia 40.932 1 203.75
2 Sextans 54.576 1 404.16
3 Quadrans/Teruncius 81.864 2 168.75
4 Triens 109.152 3 270.83
5 Quincunx 136.440 4 354.16
6 Semis 163.728 5 337.5
7 Septunx 191.016 6 320.33
8 Bes 218.304 7 104.16
9 Dodrans 245.592 8 277.5
10 Dextans 272.880 9 270.83
11 Deunx 300.168 10 260.83
12 As or Libra 327.456 11 237.5