Indigo Knight,
Digging deeper, the letters on the "SC" coin mean: C(aius) Plotius Rufus, magistrate in charge of preparing blanks and minting gold, silver and bronze coins / with the consent of the Senate ("SC"). Magistrate, in this case meant 'moneyer'; a private individual who is officially permitted to mint money.
In Latin, his title was: "tresviri auro argento aere flando feriundo" and that corresponds to the letters on the coin: VIRAAAFF.
Don....