These two cost me $4.77 each. My second one is "sort of " similar to OP's, and still cost me less than $5 in pretty good condition.
@hotwheelsearl Sure, the one at vcoins is in better condition, although the legends are off-flan. I definitely wouldn't pay that for the vcoin, but to each his own It seems that the OP issue from Mediolanum is much less frequent to get than the ones of other mints.
I would recommend to check the coin regularly while you soak it. Maybe this site could be of interest: http://www.anythinganywhere.com/info/clean.htm and there are many treads on CT about cleaning ancient coins, using the "Search" option will help you find them.
Thank you, water and a soft brush exposed a little after 24 hours, will continue for up to 24 more. That site says ammonia is ok for copper and not brass. Now the question is what is that coin made of? I am leaning more toward copper based on the orangy tone, though i'll retake the pics tomorrow once i finish stage 1 of soaking in distilld water and a wooden kebob stick also.
Let us be sure to remember that there is a major difference in a price asked and a price received in actual sale. Mine is not an exact match but each will have to decide which price quote is closer to reasonable. Mine was $12.50 in 2011 but the coins is worth more. The VCoins example is a dream listing. That is a perfectly common business model. Quote high prices and hope someone buys it. What we pay depends on how bad we want a coin and how bad the seller wants a sale. There is no RedBook for ancients.
Your coin is an Antoninianus made of billon (less than 25% silver), a term for "not very silver but silver bearing" coins of silver mixed with much copper alloy or copper with a small alloy of silver. You can see the definition here: https://www.forumancientcoins.com/numiswiki/view.asp?key=Billon
Thank you cmezner, so if i still have most of the crud, the ammonia could work? What about alcohol? It removed crud well, as does Fantastic spray. Would love to know of any know issues from people who have tried?
Your coin is bronze, not billon. It would have been completely silvered when struck...it looks like a bit still remains. I would not use ammonia on it.
according to http://www.coinproject.com/coin_detail.php?coin=251542 it is billon and numismatics.org says silver http://numismatics.org/ocre/id/ric.5.aur.139