The coinage reform of Augustus refers to the reform of

Roman currency Roman currency for most of Roman history consisted of gold, silver, bronze, orichalcum and copper coinage. From its introduction to the Republic, during the third century BC, well into Imperial times, Roman currency saw many changes in form, denomi ...

undertaken by

Augustus Caesar Augustus (born Gaius Octavius; 23 September 63 BC – 19 August AD 14), also known as Octavian, was the first Roman emperor; he reigned from 27 BC until his death in AD 14. He is known for being the founder of the Roman Pri ...

in 23 BC.

The reform

Augustus brought the minting of

gold Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile met ...

and

silver Silver is a chemical element with the Symbol (chemistry), symbol Ag (from the Latin ', derived from the Proto-Indo-European wikt:Reconstruction:Proto-Indo-European/h₂erǵ-, ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, whi ...

coins, the ''

aureus The ''aureus'' ( ''aurei'', 'golden', used as a noun) was a gold coin of ancient Rome originally valued at 25 pure silver ''denarii'' (sin. denarius). The ''aureus'' was regularly issued from the 1st century BC to the beginning of the 4th cen ...

'' and

denarius The denarius (, dēnāriī ) was the standard Roman silver coin from its introduction in the Second Punic War to the reign of Gordian III (AD 238–244), when it was gradually replaced by the antoninianus. It continued to be minted in very ...

, under his personal control without changing their weight or

fineness The fineness of a precious metal object (coin, bar, jewelry, etc.) represents the weight of ''fine metal'' therein, in proportion to the total weight which includes alloying base metals and any impurities. Alloy metals are added to increase hardne ...

. The gold ''aureus'', weighing about one-quarter

ounce The ounce () is any of several different units of mass, weight or volume and is derived almost unchanged from the , an Ancient Roman units of measurement, Ancient Roman unit of measurement. The #International avoirdupois ounce, avoirdupois ounce ...

, was worth twenty-five silver denarii, weighing about one-eighth of a troy ounce. Augustus more comprehensively reformed denominations below the denarius. New ratios were fixed among the currencies: the

sestertius The ''sestertius'' (plural ''sestertii''), or sesterce (plural sesterces), was an Ancient Rome, ancient Roman Roman currency, coin. During the Roman Republic it was a small, silver coin issued only on rare occasions. During the Roman Empire it w ...

was now minted from about an ounce of

orichalcum Orichalcum or aurichalcum is a metal mentioned in several ancient writings, including the story of Atlantis in the '' Critias'' of Plato. Within the dialogue, Critias (460–403 BC) claims that orichalcum had been considered second only to g ...

, an alloy of

copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...

and

zinc Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...

, rather than silver, and fixed at a quarter of a

. The

dupondius The ''dupondius'' (Latin ''two-pounder'') was a brass coin used during the Roman Republic and Roman Empire valued at 2 asses (4/5 of a sestertius or 1/5 of a denarius during the Republic and 1/2 of a sestertius or 1/8 of a denarius during the time ...

, formerly a two- pound

bronze Bronze is an alloy consisting primarily of copper, commonly with about 12–12.5% tin and often with the addition of other metals (including aluminium, manganese, nickel, or zinc) and sometimes non-metals, such as phosphorus, or metalloids such ...

coin, was now

, valued at half a sestertius and weighing half as much. The half-ounce '' as'', worth half a dupondius, the

semis The semis, literally meaning half, was a small Roman bronze coin that was valued at half an as. During the Roman Republic, the semis was distinguished by an 'S' (indicating semis) or 6 dots (indicating a theoretical weight of 6 uncia). Some o ...

, worth half an ''as'', and the

quadrans The quadrans (literally meaning "a quarter") or teruncius ("three unciae") was a low-value Roman bronze coin worth one quarter of an as. The quadrans was issued from the beginning of cast bronze coins during the Roman Republic with three p ...

, worth half a semis, were the first pure copper coins minted in Rome since 84 BC.

References

Coins of ancient Rome Augustus {{AncientRome-stub