Nero Tetradrachm Question

Sorry AlRashid, but just looking at the fabric leads me to think it has been cast - too much chatter in the fields, washed out details in 'protected' areas, like the panel of dots on the bust's neck, or in the feathers of the eagle. It could be environmental damage, which would make sense if it is billon. That being said, I was not able to find a die match. How's the edge?

In this case, I'd say it is a positive thing for him to have more like that. They probably come from the same source. The encrustations are a good sign; potentially, the surfaces are the result of the removal of the original patina, revealing corroded surfaces, with these black marks not being removed in the process (but would also reveal porous surfaces). Bad surfaces are especially common in later tetradrachms. The sunken retrograde Z and the OP on the second coin is an effect that is quite commonly seen on sestertii, a curious side effect sometimes seen from regular corrosion, but wouldn't occur in the casting process unless tooling was applied. I couldn't find die matches for either of them, which is also a good sign.

The silver content is much too high for the series, unfortunately. It seems to me like you have a coin cast in sterling silver (925). Per this paper (https://warwick.ac.uk/fac/arts/clas..._article.pdf), this series of Nero tetradrachms from Antioch have a consistent silver content of around 70%, with a gold content of closer to 0.2-0.5%.

Well, a lot of coins were reconstituted over time. Most commonly orichalcum coinage as the mines had run dry. But it seems the metallurgists were quite serious about silver content in Antioch, given the consistency seen compared to the early empire days. It seems to be suggested that old issues were withdrawn to provide consistency when the second phase of Nero tetradrachms (like yours) were released. It should also be considered that they wouldnt melt down a single coin; they would have to do the coins in batches. Your coin is dated 109, so the second year of the second phase, by which time earlier tetradrachms were already withdrawn. The only Claudius coin they examined was a didrachm and reportedly these are very rare (probably low issuance, given their silver content, or perhaps the withdrawal process was much more stringent for these). I expect that all the second phase Nero tetradrachms were produced in 700 silver by design - including more silver in a coin would of course cost the mint money.

The conclusion of the paper is very interesting because it gives an idea of why a new series was issued at this time in a higher fineness than earlier imperial tetradrachms. Tyre still used its old high quality tetradrachms which had 4/3rds the silver content of the new imperial tetradrachms. The author suggests that the old imperials coins would have therefore been tariffed at 3 drachms, but by raising the silver content slightly and simultaneously withdrawing the Tyrian tetradrachms, new Nero tetradrachms could be tariffed at 4 drachms, even though they contain much less silver than the Tyrian coinage.

Good thinking - could be the case. 'Leaching' copper out of coins to make them appear to be finer silver is a common practice and would also enrich the gold content (you'd expect they'd remove the gold from modern silver, but I don't know about that). Strong acid would also cause this sort of surface. I think the only way to be sure would be to make a test cut...

I think you are probably right. It would also be interesting to see if old sterling is devoid of gold - theres still loads of old sterling cutlery getting melted down. That being said, I sincerely doubt that would affect this case.

What is interesting is that people who make fake ancient statues have been known to melt down old coins to make them - that would take an awful lot of grots to achieve.

Interesting. Presumably, their coinage was all authentic, so I wonder why the numbers are so off? Or maybe all the numbers are fine and you simply have higher silver content at the surface of your coin.

Do you have any low silver billon coins around? I'd be interested to see how low the silver content can go before it stops looking silver.

Ben, I am thinking that maybe my coins were cleaned and that chemical used to clean them causes some leaching and enriched the surface silver to be higher as you can see both Caligula and Nero coin have close reading on silver and on the gold content and also both coins surface looks porous . I attached the XRF for Nero for comparison