Aureus
The aureus (pl. aurei — "golden") was a gold coin of ancient Rome originally valued at 25 pure silver denarii. The aureus was regularly issued from the 1st century BC to the beginning of the 4th century AD, when it was replaced by the solidus. The aureus was about the same size as the denarius, but heavier due to the higher density of gold (as opposed to that of silver.)
Before the time of Julius Caesar the aureus was struck infrequently, usually to make large payments from captured booty. Caesar struck the coin more often, and standardized the weight at of a Roman pound (about 8 grams). Augustus (r. 29 BC – 14 AD) tariffed the value of the sestertius as of an aureus.
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