Question on Postumus Coin...

[Othereal]

Quick question on a Postumus coin I have. This Antoninianus is listed as silver, but on the bust crown, there is a patch that appears to be copper or bronze although the rest of the coin appears to be silver. Is this a common occurance where poor bullon is used for the coin, or is this possibly a fake?

Hi
Some roman coins were made of brone then silvered on top , this looks like one of then its not a fake as far as I can tell

[mrichter]

This coin looks authentic to me. As already mentioned the coin could be bronze with a silver wash. However, it is more likely that the coin is Billon, an alloy of bronze and silver that was used instead purer silver.

Regards,

Matt

I agree, and remember that by the time Postumus was ruling, Roman coinage was significantly devalued so you don't get the same quality that earlier emperors used in their coins.

[Gunner]

I've seen this phenomenon on other lower quality billon coins. I believe what you see is the result of copper precipitating out of the coin over time...I think this phenomenom is one of the main reasons that late roman argentii and siliquae have flan cracks. If you will check my tantalus gallery I have a billon argenteus of Constantine the great that exhibits this precipitation characteristic.

[Othereal]

Thanks for all the replies. I only have a couple AR coins, so I don't have the experience with them that many of you have. It does look more like leaching than a silver wash, as it only appears in one spot on the coin. I appreciate the help.

I agree, and remember that by the time Postumus was ruling, Roman coinage was significantly devalued so you don't get the same quality that earlier emperors used in their coins.??