Solidus (coin)
Constantine the Great reintroduced the solidus for mass circulation in 324 or 325. This gold coin weighed about 4.5 grams and was struck at a rate of 72 to a Roman pound. Each coin contained roughly 189 milligrams of pure gold, though refining techniques meant actual purity reached 95.8 percent. The initial design featured the emperor with a spear over his shoulder, a portrait that remained conventional for over a century in the Eastern Roman Empire from 395 to 537. Before this reform, the aureus had been replaced by the new standard. By the time Constantine issued these coins, they were worth 275,000 increasingly debased denarii. Those older silver coins held just five percent of the silver value they possessed three and a half centuries earlier.
The mint at Constantinople produced most solidi from the fourth through the eleventh centuries. Branch mints operated in Trier, Rome, Milan, and Ravenna during the fourth century before Germanic invasions closed many facilities. By 410 only Rome, Ravenna, Constantinople, and Thessalonica continued striking gold solidi. Justinian I reopened several mints after reconquering territories like Carthage where great numbers of solidi were struck. In the early seventh century, the Carthage mint began producing small globular solidi about half the size of normal issues but much thicker. These unique coins circulated until Arab conquest in 698. The Syracuse mint grew significantly under Constans II when he briefly moved the empire's capital there. Syracuse solidi became lighter at roughly 3.8 grams and reached only 19 karats fine compared to imperial standards.
Michael IV the Paphlagonian assumed the imperial throne in 1034 and began slowly debasing both tetarteron nomisma and histamenon nomisma. The process accelerated rapidly over subsequent reigns. Constantine IX Monomachos reduced purity to 21 carats or 87.5 percent between 1042 and 1055. Constantine X Doukas lowered it further to 18 carats or 75 percent from 1059 to 1067. Romanos IV Diogenes pushed the standard down to 16 carats or 66.7 percent during his rule from 1068 to 1071. After losing the Battle of Manzikert, the empire's revenue generation deteriorated while coin purity continued falling. Michael VII Doukas reached 14 carats or 58 percent between 1071 and 1078. Nikephoros III Botaneiates dropped it to just 8 carats or 33 percent from 1078 to 1081. Alexios I Komnenos allowed purity to fluctuate between zero and eight carats during his first eleven years before abolishing the solidus entirely in 1092.
Imperial law forbade merchants from exporting solidi outside imperial territory yet enforcement remained loose. Many coins have been found in Russia, Central Europe, Georgia, and Syria despite restrictions. Lightweight solidi became especially popular for foreign trade with Europe and appeared frequently across those regions. In the seventh century they became desirable circulating currency within Arabian countries. Since these coins circulated outside the empire were not used to pay taxes to the emperor, they did not get reminted. Soft pure-gold coins quickly became worn through constant handling. Arabian copies known as dinars minted by caliph Abd al-Malik ibn Marwan began circulating in areas outside Byzantine control after the end of the seventh century. These dinars corresponded in weight to only twenty siliquae but matched lightweight solidi circulating in those same areas. The two coins circulated together for a time before the Umayyad Caliphate issued its own gold dinar starting in 697.
The word soldier ultimately derives from solidus referring to the gold coins with which soldiers were paid. In French language evolution solidus changed to soldus then solt then sol and finally sou. No gold solidi were minted after Carolingians adopted the silver standard. Thenceforward the solidus or sol became a paper accounting unit equivalent to one-twentieth of a pound of silver divided into twelve denarii or deniers. The monetary unit disappeared with decimalisation and introduction of the franc during the French Revolution in 1795. Today in French around the world solde means balance of an account invoice or sales seasonal rebate. It remains the specific name of a soldier's salary. To this day avoir des sous indicates being rich while être sans un sou signifies being poor. In Italian the verb soldare means hiring often soldiers or mercenaries deriving exactly from historical usage patterns.
French Canada uses cent and centime as terms for the Canadian cent though European French forms differ significantly. Quarter dollar coins in colloquial Quebec French sometimes called trente cents because of exchange rate changes making twenty-five cents equal fifteen halfpence. After British conquest of Canada in 1759 French coins gradually fell out of use. Spanish pesos and U.S. dollars circulated alongside local currency until 1841 when exchange rates fixed at four dollars equals one pound. The Peruvian sol was introduced at a rate of 5.25 per British Pound representing just under four shillings. The term soles de oro appeared in 1933 three years after Peru abandoned the gold standard. By 1985 the Peruvian sol replaced itself at one thousand to one by the inti sun god of Incas. A new sol emerged again in 1991 at a million to one ratio before stabilizing. Vietnamese borrowed the French term sou as xu meaning coin often used in compound forms like đồng xu or tiền xu.
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Common questions
When did Constantine the Great reintroduce the solidus for mass circulation?
Constantine the Great reintroduced the solidus for mass circulation in 324 or 325. This gold coin weighed about 4.5 grams and was struck at a rate of 72 to a Roman pound.
Which mints produced most solidi from the fourth through the eleventh centuries?
The mint at Constantinople produced most solidi from the fourth through the eleventh centuries. Branch mints operated in Trier, Rome, Milan, and Ravenna during the fourth century before Germanic invasions closed many facilities.
How much pure gold did each original solidus contain compared to its total weight?
Each coin contained roughly 189 milligrams of pure gold though actual purity reached 95.8 percent due to refining techniques. The initial design featured the emperor with a spear over his shoulder and remained conventional for over a century in the Eastern Roman Empire from 395 to 537.
What happened to the purity of the solidus under Alexios I Komnenos before it was abolished?
Alexios I Komnenos allowed purity to fluctuate between zero and eight carats during his first eleven years before abolishing the solidus entirely in 1092. Previous rulers like Michael VII Doukas had reduced purity to 14 carats or 58 percent between 1071 and 1078.
Why did the word soldier ultimately derive from solidus referring to gold coins?
The word soldier ultimately derives from solidus referring to the gold coins with which soldiers were paid. In French language evolution solidus changed to soldus then solt then sol and finally sou.