The issue of plated coins was sometimes practised by the ancient Greeks, as is known from some extremely rare examples in electrum of the earliest period of coinage, and from the not uncommon occurrence of plated silver money. A famous example in silver is the Stater of Themistocles, the Athenian, issued at Magnesia, Ionia, circa B.C. 465-449 (Brit. Museum). This is not regarded as an official issue, but a private forgery, for the Paris specimen is not plated and is from different dies. The practice was not general, and as a state measure was rare. However, one finds plated silver coins among Greek issues, and sometimes from identical dies with the official pure speciments, so that they can scarcely be regarded as of private origin. The Romans, on the contrary, struck plated silver coins as legal state issues for profit. The earliest are said to be those struck in B.C. 91 during the war with Hannibal. In B.C. 84 these plated pieces were recalled. But Sulla cancelled this measure, and plated coins were issued in certain quantities until Augustus' reform in B.C. 15. Plated coins continued to be issued under the Empire for exportation. One must distinguish between the Roman silver pieces of careful style and those of barbarous execution, the latter being doubtless the product of false moneyers. Plated coins were designated by the Romans Nummi mixti, Subaerati, or Pelliculati, terms which refer only to such pieces as had a core of base metal, e.g., copper, lead, etc., covered with a thin plate, usually of silver, though plated gold coins are found among the Roman imperial issues.
The French equivalent is Monnaies Fourrees, and the German is Subaerati, or Gefutterte Munzen, but these terms never refer to coins of debased metal.
See Also: Plated Coins
Source: Frey's Dictionary (American Journal of Numismatics, Vol. 50, 1916)