Pentanummium: 5-Nummi Byzantine Monogram Coins

Illustrated Specimen Details: Bronze Pentanummium

Example Specimen: Pentanummium, 565-578 (Byzantine Empire)

Authority & Identification: This bronze coin was issued by the Byzantine Empire (Eastern Roman Empire) during the reign of Emperor Justin II (565-578). The obverse displays the monogram of Emperor Justin II. The reverse features the large Greek letter "Є", which indicates the denomination of the coin as 5 nummi or a pentanummium. Below the denomination indicator, the letter "K" marks the Cyzicus Mint (Ancient Greek "Κύζικος"), an ancient Greek town in Mysia (Anatolia) located within the current Balıkesir Province of Turkey.

1. BYZANTINE EMPIRE (5th-7th centuries): pentanummium = 5 nummus

PENTANUMMIUM as coin name. Pentanummium (Greek "πενтаνούμμιον") was a small copper or bronze coin of Byzantium of low production quality, equivalent in value to 5 nummi (singular: nummus). The name of the coin literally means "five" (Greek "πέντε") "nummi". They were produced mostly during the 6th century. During the 5th-8th centuries, the Byzantine Empire used several similar denominations in monetary circulation, each of which bore a corresponding letter designation on the reverse to indicate its value. For example: "Є" represented the pentanummium (5 nummi), "I" stood for the decanummium (10 nummi), "K" denoted the semifollis (20 nummi), and "M" signified the follis (40 nummi). Pentanummia were issued by several Byzantine mints: Constantinople, Antioch, Nicomedia, Ravenna, and Chersonesus. A typical layout for the coin features a monogram or portrait of the ruler on the obverse, and the designation of the denomination on the reverse ("Є" = 5).

History and Evolution of the Pentanummium

Origins and Monetary System

The pentanummium became prominent following the broad monetary reforms enacted by Emperor Anastasius I (491-518) in AD 498. These historic reforms reorganized Byzantine bronze coinage and introduced clearly denominated multiples of the nummus, which was the smallest Byzantine accounting unit. Like the decanummium and the follis, the denomination was named directly according to its numeric value. In the Byzantine monetary system, 1 pentanummium was equal to 5 nummi. Consequently, 2 pentanummia equaled 1 decanummium (10 nummi), 4 pentanummia made 1 semifollis (20 nummi in the earliest system, later 40 nummi), and 8 pentanummia made 1 follis of 40 nummi.

Physical Characteristics and Mints

Pentanummia were usually minted in bronze or copper. Because they represented the lowest circulating denominations, they were small, thick, and often crudely struck. Common designs featured imperial busts, Christian symbols, crosses, and royal monograms. Pentanummia were struck at major Byzantine manufacturing centers, including Constantinople, Antioch, Alexandria, Nicomedia, Carthage, Thessalonica, Ravenna, and Chersonesus. The weight of these coins was typically close to 2-3 grams. The standard layout included an imperial image or monogram on the obverse and the Greek numeral "Є" (representing 5) on the reverse.

Economic Role and Numismatic Value

The pentanummium served as a petty circulation currency, market coinage, and small change for daily transactions throughout the Byzantine Empire. It was particularly useful for minor food purchases, local trade, and urban commerce where larger silver or gold denominations were impractical. Because of their small size and generally low production quality, combined with extensive circulation wear, it is extremely difficult to find pentanummia in perfect condition in modern numismatic collections. Today, monogram types are especially popular among collectors, who particularly value early Anastasius I issues, Justinian I examples, and rare provincial mint varieties from rulers like Justin I (518-527), Justin II (565-578), Tiberius II Constantine (578-582), Maurice (582-602), and Heraclius (610-641).