The denarius was a small silver coin. It was made by the Roman Empire and Roman Republic a very, very long time ago (about 2000 years to be precise). The denarius weighed about 3 to 4.5 grams. It was the main coin of Ancient Rome. During the Empire the front side usually had a picture of the emperor on it. The coin was sometimes made of copper and painted silver in color. It was shiny but is less shiny now.