Hey guys, picked up this coin because I thought it looked odd, I'm used to seeing these Gordians ant's in pretty good silver. Does anyone know the story on this coin which seems to be mostly AE?? The coin weighs 3.7g and 22mm
The style does not strike me as just quite normal so I would suspect it is an unofficial or barbarous issue. It would be better to hear the opinion from someone more specialized in Gordian. There are circumstances of burial that can do this to a low grade silver coin as used in this period so I could not completely rule out the coin looking silver when new.
It looks like a double Denarius, which is the only coin of his I know with that reverse, with the legend Roma Aeternae However, yours looks Ae rather than AR, so I'm stumped. The weight would also suggest double Denarius to me. Could be a limes Denarius? Or maybe the core of an ancient forgery? Sometimes with ancient forgeries the core is all that remains of the previously plated coin.
Possibly a fouree core or a bronze antoninianus of unofficial issue. There's no way of knowing whether it was meant to deceive, or officially sanctioned and produced in a Roman territory that had a dearth of official coinage. Doug points out that the style is a little off of normal, which is true, but I think it's clear that the engraver didn't just imitate the Roman style, but tried to copy it as faithfully as he could. In my experience, unofficial ants of Gordian III are pretty rare. There are many more to be had from earlier periods, like the Severan Dynasty. I don't see them very often from this period, so it's definitely an interesting find.
The details seem awfully crisp for a fouree core. Perhaps it's just heavily toned? I've seen ants of that color before. I agree that the style looks off, although I'm not familiar with his coins from Antioch; it's possible that it's from there. Size and weight seem okay.
A very interesting Gordian III you have. I recently bought a similar coin, supposed to be silver (to some extent) but not. It is an antoninianus of Volusian which I believe is RIC 237b, with the incorrect VDERITAS spelling (a common error for these, apparently), and four dots both obverse and reverse (Antioch mint). It appears to have no silver in it whatsoever, not a fourrée, not plated. I know the silver content on these are low to begin with, but this one appears to have no silver at all. It weighs 3.14 grams. I sent a query to this really terrific website called "Four Bad Years" with a wonderful run of coins, fully described, from 249-253. I highly recommend the site: http://sonic.net/~marius1/mysite/ I got an immediate & friendly response from the site's owner, Richard Beale, telling me that chemical processes or fire can leach away the silver in a low-silver coin. He also said he's seen these types mixed in with good coins in several instances and that he is confident mine is ancient. The problem is that Volusian ants are quite a bit lower in silver content than a typical Gordian III, so I am not sure my example is very useful. But it is still an interesting Gordo!
The story is that the Antoniniani were debased between 240 and 270 AD from 40% fineness to 5% silver fineness. The mints used a special heating and cooling down method to put the silver mostly on the surface and the copper mostly in the core. Probably didn't work out very well in all the various mints in the Roman empire. Looks near 100% silver , but actually no more then 40% fineness: This Volusian looks OK too, silver fineness 30%
There is a scientific study that sought to analyze the exact surface and interior composition of different Roman coins, and prepared blanks and used the different suggested techniques for how the Romans might have enriched the surface of coins to make debased coins look like good silver, to see which techniques could replicate the actual surface and interior structures of Roman coins. The study was titled "Silver surface enrichment of silver-copper alloys: a limitation of for the analysis of ancient silver coins by surface tehcniques," which was published in the Nuclear Instruments and Methods in Physical Research B226 (2004) 153-162. Their research shows that they could replicate the differing concentration of silver surface and internal layers of Roman coins using several theorized pre-production methods, and that post-production treatment of the flans was not necessary. The team examined the methods of enrichment proposed by L.H. Cope in the article "Methods of Chemical and Metallurgical Investigation of Ancient Coinage," RNS Special Publication No. 8, 1972, p.261. Cope proposed 5 steps, (1) casting a button of silver-copper alloy, (2) heating the button in air to form a layer of copper oxides, (3) acid-pickling the blank for removing the copper oxides and revealing the silver-phase, (4) hammering the blank for spreading silver-phase laterally, and (5) striking the blank. The results demonstrated that for coins of more than 15%-20% Ag in the silver-copper alloy, steps #2 and #4 were not necessary as the heating achieved during the casting of the original silver-copper alloy button was sufficient to create a substantial silver rich surface. However, for coins of lower Ag content, steps #2 and #4 were still valid. So basically, the Gordian and Volusian coinage would have been enriched by heating flans of silver-copper alloy, acid-pickling the flans, and subsequently striking the flans with the dies. That was all there was to it. As for the pickling mixture, I've read somewhere else, though I can't recall the source, that urine might have been used as it was an acid that was in ready supply to the Romans. As you all know, urine is mildly acidic. So yeah, there is a possibility that precious coin you are holding was soaking in a tub of Roman urine 1,800 years ago. Now, obviously once you get to really low silver content like 5%, no amount of heating, pickling, striking, etc, will make that puppy look like silver, so plating would have been used. How the Romans plated those coins, I've yet to examine. Maybe someone here has insight into that.
Sallent's post covered the matter well as I recall hea.ring it but we do need to remember one additional thing when looking at any coins. That is variability within a sample, an issue, a mint or even a coin. We see some coins that just do not appear to have been well mixed in the alloy so there will be blotches of color and texture. We will find coins that should be identical but are better or worse in terms of silver. Both of these could be variations in the original alloy or in the degree the pickling process (regular or hi-test urine?). When there were several mints in operation, we can not assume that each followed the same 'recipes' when making coins. Add to that the old fact that things like weight and alloy could be an overall average with little effort made to make every coin or every day's production match as long as they produced the full number of coins and used the proper amount of metal. I'd like to see more study put into whether mints tracked overall weight and fineness separately or if they measured the precious silver and mixed in copper or pot metals and varied weights so coins with lower grade silver might be expected to weigh more. I doubt many alloys were made using pure silver and pure copper. When old coins were being melted into the mix, tracking the results and keeping them consistent would be quite a job. There are collectors and students with specialist interest in metallurgy rather than types. One some of you might know is Robert Tye, author of the standard work Jitals. Gordian fans might like Minting of Antoniniani A. D. 238-249 and the Smyrna Hoard (Nuismatic Notes and Monographs, No. 156), Eddy, S. K. which comes in paper and electronic versions these days. I believe most of the NNM series are out there free somewhere but I did not do the research. I have a paper original (old fashion book). I have seen sharper transfers than this one but it is the book. https://www.scribd.com/document/255...238-249-and-the-Smyrna-hoard-by-Samuel-K-Eddy
Sallent's coin is a different issue from the OP, in that the obverse inscription is different. His is RIC 55, whereas the OP's is a later issue, RIC 70, and the bust style may therefore be different. There is an earlier one still, not represented in this thread, RIC 38, with the obverse inscription IMP CAES M ANT GORDIANVS AVG.
I guesse I'll add this one to the mystery pile, thx for all the great insight. I Have some reading to do. Very interesting on the techniques they used in this time period to make these Antoniniani seem like good silver. I had no idea they could have that low content and still appear AR.
