Various sources estimate the current-day value of a sestertius, or one quarter of a denarius, at between $10 and $12, although estimates vary greatly. This would have meant that a share in the Vipasca mines might have cost $40,000-$50,000 in modern-day terms. In Roman terms, $4,000 sesterces would have been a significant sum; remember that equestrians had to possess a minimum of $400,000 sesterces, and senators over a million.

These conversion figures are very inexact, however, and the precise value of one sestertius at the time of the bronzes' writing remains one of my primary lingering questions.