Copper shows on just about every high point on both sides. I assume (but do not know) this to be a contemporary counterfeit.
From the very beginning of precious metal coinage a certain number of coins were made with a precious metal 'skin' over a base metal core. These 'plated' or 'fourree' (also seen spelled with one 'r' or 'e') pieces were intended to look like their solid counterparts and circulated until the core broke through betraying their nasty little secret. When late Roman silver coinage deteriorated to the point that the alloy was no longer silver in color, official mints applied a thin silver wash to serve as a reminder that there was some silver in the alloy. These are not considered 'fourree' since their purpose was not to deceive (much in the same sense as the current U.S. clad coinage). When currency reforms returned a good silver coin to circulation, production of plated pieces resumed. This process was used long after the end of ancient era. Most plated coins are silver over copper but gold over copper and gold over silver coins exist. There are even a few coins of bronze over iron!
Slver foil technique - Possibly regular mint product?
|A most important point to remember when discussing plated coins is that what is proven true for one does not necessarily hold true for another. This applies both to the techniques of manufacture and to their reasons for issue. While many advanced students of numismatics disagree, I maintain that SOME fourrees were produced at SOME official mints. MOST, however, were unofficial at least to some degree. Coins could be produced by mint workers 'moonlighting', by persons using retired or stolen dies, by local authorities creating a 'money of necessity', by barbaric people making an 'imitative' coinage and, finally, by out and out counterfeiters. Unfortunately, it is not always possible to determine which of these categories applies to any particular coin. Our best educated guesses will remain just that: guesses.|
Otho - 69 AD - Fourree denarius - SECVRITAS PR
| Of the plated coins in my collection, the most exceptional is this denarius of Hadrian.
Individually, fourree coins and brockages are rather common. This coin is unusual in that it combines both of these 'varieties'. I have seen two other examples of this combination.
The lower inset magnification of a small area from the reverse shows a pit in the silver that passes through a (white in the photo) region of silver copper alloy which bonds the relatively pure silver on the surface to the copper core. This alloy, the 'eutechtic', is the mixture of 72% silver and 28% copper and has the lowest melting point of any combination of these two metals. This material is used as silver solder. Fourrees were produced by wrapping the copper core with silver foil. This sandwich was heated and struck with dies. If the heating and the force of striking were sufficient the two layers would adhere producing a thin layer of eutechtic at the bond. Some workshops strengthened this bond with a powdered eutechtic sprinkled between the layers. It is not always easy to tell which method was used on any particular coin but the thickness seen in this photo suggests that this coin was produced with this 'added eutechtic' technique.
For more technical information on fourree production techniques and great cross section photos, see:
On the following pages, I have posted a discussion of fourree coins with many photos. Persons interested are welcome to visit:
Republican/Imperatorial Plated Coins
Roman Imperial Plated Coins
Greek Plated Coins
© 1997 Doug Smith