The phrase references a specific type of United States ten-cent coin, minted from 1916 to 1945. It derives its value from its composition, being made of 90% silver and 10% copper. It is also associated with a specific imagery, resembling mercury.
These coins hold significance for several reasons. Their intrinsic silver content makes them valuable as a precious metal investment. They are sought after by collectors due to their historical importance, design artistry, and relative scarcity, especially in higher grades. Their association with a Roman god gives them an aura of cultural significance.
