Aureus

The aureus (pl. aurei, 'golden') was the main gold coin of ancient Rome from the 1st century BC to the early 4th century AD, when it was replaced by the solidus. This type of coin was sporadically issued during the Republic and standardized during the Empire, originally valued at 25 silver denarii and 100 sestertii. It was about the same size as the denarius, but heavier than the denarius since gold is denser than silver.