Philoppopolis, Elagabalus--bronze and silver

[Charles M]

Here are 2 coins form my collection.  Both are Philoppopolis, Elagabalus, Varbanov 1787.  The coin on the left is bronze while the one on the right is silver (not silvered).  Now I know this occurs sometimes with imperial silver denarii but I've never seen it with a provincial coin before.  How often does this occur?

Left coin: 20 mm, 3.33 grams
Right coin: 18 mm, 4.47 grams

[Charles M]

It doesn't show well in the picture but in hand the coin on the right is very obviously silver.

[shanxi]

Very unusual. Only a few provincial cities were allowed to mint silver coins, and at least Varbanov shows no silver coins for Philippopolis. Also Varbanov 1787 is listed as bronze coin.

[Charles M]

So I wonder if this was an error?  Was it a trial run?  Since provincial cities were not allowed to mint silver coins, why would they have a silver flan?  It's the same size as a Roman denarius: I see no evidence of it but could it have been struck over a denarius?  Very strange.

Charles M.