Roman Coins: Interpreting the Inscriptions

What Roman province was allowed to mint its own small-value coins without the portrait of the emperor?

Roman coins from Frome Hoard in England
Part of the hoard of more than 52,000 Roman coins found by Dave Crisp using a metal detector near Frome in Somerset, England

Coins are especially valuable in dating archeological sites because they can provide a definitive terminus post quem, a point in time after which a particular level in a dig was actively inhabited. While a layer might be much younger than the date of a coin found there, it can’t be older.

The availability of reasonably priced metal detectors has transformed the way promising dig sites are found. A large number of history buffs are willing to spend their free time sweeping the countryside of former Roman provinces, like Britannia where the Frome Hoard was found in 2010. They have located many sites that were inhabited in antiquity. The Roman coins help archeologists date different layers as they dig. Coins of the imperial period are especially useful since they include the portrait of the emperor and enough information about his titles and offices to provide a narrow range of possible dates for the minting of a specific coin.

The Obverse (Head) Side of a Roman Coin

During the Republic, the obverse of most Roman coins featured an image of a deity. At the end of the Republic, portraits of real humans appeared. The first may have been that of Pompey in 46 BC after his murder. Julius Caesar and other prominent generals were also illustrated. When Augustus became princeps civitatis (“first citizen” aka emperor) in 27 BC, he continued the tradition of having his profile on the “head” side of the coins.

It was customary to have the subject showing the right side of his face, but there were exceptions. Depending on the mint, the portrait might vary. That was especially true of coins from the eastern mints. The emperor might be shown with a laurel wreath (laureate), a crown of spikes like the sun’s rays (radiate), or a crown of jewels (diademed). While the portraits were fairly representative of the actual appearance of the early emperors, a more stylized portrait based on the Greek ideal became more common after the late 3rd century.

Each time there was a change of emperor, new coins were struck bearing the new emperor’s image. But the coins convey much more detailed information than the portrait and name of the emperor at the time of their minting. Roman coins bore inscriptions so lengthy that abbreviations were used to fit so much information onto a small piece of metal. The inscriptions might relate to the vows taken by an emperor when he began to rule and which he renewed every five years. They might also relate to the constitutional offices he held and other details of his reign.

The following table lists some of the common inscriptions. A number following the tribunicia potestas showed the number of years an emperor had reigned. After AD 350, the personalized details were replaced by general terms.

Imperial coin inscriptions

Roman Mints and Mint Marks

As with US coins today, the location of the mint where the Roman coins were struck was sometimes indicated on the coin. Until the end of the 2nd century AD, there was a central Roman mint. During the Republic, most coins were minted at the temple of Juno Moneta in Rome or at Capua. In the Late Republic and early Empire under Augustus, generals in the provinces and legates appointed by the Augustus to command legions sometimes minted coins for use in the provinces under their control. From 10 BC to AD 82, a mint was located at Lyon.

Roman coin denominations and composition

While gold (aureus) and silver (denarius) coins were minted by the emperor, the lower value coins of bronze (an alloy of copper and tin)  and brass (an alloy of copper and zinc) were officially issued by the Senate until the time of Aurelian (AD 270-275).  After Aurelian, the emperor issued all coinage.

The eastern provinces had their own mints for small bronze, brass, and copper coins. Before the Jewish Revolt of AD 66 to 73, the local coinage struck for use in Judaea did not include features, such as the emperor’s portrait and titles implying divinity, that would violate the Mosaic prohibitions on making images of idols and worshiping other gods. After the Bar Kochba Rebellion of AD 130 to 134, what was formerly Judaea was merged with the province of Syria and would no longer mint its special coinage. The situation between the two rebellions is not clear.

Provincial mints became more important after the civil wars of the late 2nd century. During the reign of Gallienus (AD 253-268), mint marks that identified a coin’s point of origin became common. During the reign of Diocletian (AD 284 to 305), the systematic use of mint marks was adopted.

For very early coins minted in or near Rome, the mint mark might be only the number assigned to the particular workshop (officina) where it was struck. During the Late Republic, the particular batch of coins or the particular die used to make it might be indicated by some symbol. As time passed, both an abbreviation of the location of the mint and the number of the workshop within the mint where it was struck were included.

Different forms of workshop abbreviations

Roman numeral: I, II, III, etc.
Officina + Roman numeral: OF I, OF II, etc.
The workshop number might be written out (PRIMA, SECVNDA, TERTIA) or abbreviated (P, S, T).
The number of the workshop might even be written in Greek.

Mint Marks from the Major Coin Mints

Roman coin mint marks


Adkins, Lesley and Roy A. Adkins. Handbook to Life in Ancient Rome. New York: Oxford University Press, 1998.

Korb, Scott. Life in Year One: What the World Was Like in First-Century Palestine. New York: Riverhead Books, 2010.

Coins from the Frome Hoard. Photo by Portable Antiquities Scheme from London, England (Close up of the coin hoard) [CC BY-SA 2.0 }, via Wikimedia Commons