Kiaora

You’re welcome! Regarding purpose: Given the significant difference in size and weight between the the current coinage and the counter-marked coins, perhaps they had a non-monetary purpose, eg. some sort of ticket or pass token? (pure speculation - I’ve never read anything proposing this)

Great write up and here's another example that makes yours look positively FDC! I am not even sure which way up the obverse photo should go. As far as I can tell, the host coin, as is the OP, is a very worn pre-reform follis of either Justin I or Justinian I, with the eagle counter mark placed very carefully over the officina letter. I was intrigued by the progression of the theories. To expand a little on the original post (apologies for any duplication) these were: Bendall (1976) Simon Bendall published a short note in the 1976 Numismatic Chronicle (page 230), noting 3 specimens. While he highlighted that one had ‘long been known’ … ‘the exact design was unrecognised until the discovery of another, better preserved, specimen’. He believed that the countermarks must have been contemporaneous to the issuing of the original coins, I.e. c. 517-539, based on the observation that the the countermarks were as worn as the coins. While the potential for the countermarks to be dated to the reign of Heraclius (given that other countermarks of pre-reform coins use Heraclian monograms and so can firmly be associated with his reign), this was dismissed as unlikely on the basis that ‘the imperial monogram would surely be more prominent’. No conjecture was made as to place of issue or any potential local significance. Hahn (1978) In a subsequent Numismatic Chronicle article focused on 3-nummi and 1-nummus issues from Alexandria with an eagle on the obverse, Hahn argued that the countermarks were better associated with Heraclius. On the basis that these eagle countermarked coins and the 3-nummi pieces are closely associated, he noted that the form of the eagle was based on the scipio or consular sceptre surmounted by an eagle, with its wings raised. This adornment did not appear earlier than Tiberius II, thus ruling out a Justinianic dating for both the Alexandrian nummi, and by correlation, the countermark. Further, Hahn associated the nummi and the counter marked coins with Alexandria, and dated them to 613-17 thereby placing the eagle countermark as being concurrent with the Heraclius monogram countermarks. Goehring (1983) In a short note in the 1983 Numismatic Chronicle, Goehring highlighted 2 further examples of the eagle countermark, both found during archaeological excavations in Upper Egypt between 1975 and 1978. He noted that the find spot supported the idea of the countermark being ‘of a local Egyptian significance’, and that the well-preserved condition of one of the countermarks supports a Heraclian dating (per Hahn, and contra. Bendall). Schulze (2005 and 2009) In his second 2009 article, published in Israel Numismatic Research, Schulze expanded the list of known specimens to 25, which strengthened his tentative 2005 hypothesis that the place of striking was not Egypt, but Palestine. Of the coins with a known provenance, 3 were excavated or acquired in Egypt, compared to 17 from Palestine. Caesarea Marítima was proposed as the location of minting. He also published an example of the countermark on a follis of Maurice Tiberius, precluding once and for all a Justinianic dating and confirming the Heraclian dating in face of some residual doubts. He rejected Hahn’s dating of 613-17 on the basis that there ‘is no historical starting point for such a monetary measure’; after all from 610-630 Syria was occupied by the Persians who produced a dedicated coinage, and no contemporary Syrian countermarks are known. He therefore proposed 637-640, following the battle of Yarmouk in 636 after which Caesarea was under siege between 639 and 641. They were therefore issued during a period of shortage of coins and thus the need to revalue coins previously out of circulation. Woods (2015) Finally, in a paper in Greek, Roman, and Byzantine Studies 55 (2015), Woods published 2 further examples, and made the case for re-dating the issue to 610, ordered by Nicetas as he ‘advanced from Egypt into Palestine during the summer of 610 in order to signal the change of government from Phocas to the Heraclii as consuls’ - at the same as noting that ‘there is no easy and obvious answer to the question who it was that stamped the eagle countermark on the folles …, or why this authority did so’.

While there terms are often used interchangeably, here’s a good overview from a 2012 Forum Ancient Coins post by Heliodromus: Follis is certainly wrong - this was the Roman name for a *bag* of coins of value 12,5000 "denarii communes" (i.e. denarii at a time when it was just an accounting unit, no longer an actual coin denomination). I'm not sure who introduced the incorrect modern usage of this name.The name nummus is probably the best. There are contemporary references to this name being used for the bronze/billion coinage at the time of Diocletian's monetary reform, and the same name appears to have still been in use at least as late as c.321AD per reference to this coin's (nummus) value being halved, apparently in reference to a revaluation that occurred at the time Licinius introduced new coins marked "12 1/2" [denarii communes].The issue of denominations/naming is complicated by Constantine's coinage reform of c.318AD when (per modern testing) he significantly increased the silver content of the bronze/billion coinage (from 1-2% to 4-5%), and reintroduced older reverse types associated with a higher yet (20%) silver content. Presumably per the increased silver content (and intended value association), this coinage reform increased the value (tariffing) of the bronze/billion coinage, and the question then becomes whether the denomination name stayed the same (nummus), or changed.Given the apparently (c.321AD) post-reform use of the name nummus, it seems the safest guess is that the name nummus persisted after Constantine's c.318AD reform, but others have suggested that the denomination name changed and have equated this to the known "centenionalis" of this approximate time. The competing theory is that the "centenionalis" instead refers to a slightly later denomination introduced after Constantine's death.

Reference to type, not the actual coin I think despite the low resolution image

Size of the bust and relief are the (too subjective in my opinion!) distinction made by RIC

The first coin is Constantine II, from Trier The second coin is Constantius Gallus

Assuming these are all of Constantius as Augustus, I would concur with your assessment except for the last one which I would classify as rosette-diademed. Volume 8 has Constantius predominantly with pearl-diademed and laurel and rosette diademed, and only a couple of instances of rosette diademed Allan

Only if cheap for the Black Cabinet! It’s a fake - nonsense obverse legend, poor style -especially the eyes and mouth, and listed on Forum Ancient Coins https://www.forumancientcoins.com/fakes/displayimage.php?pid=231

That’s some excellent detective work!

It’s an obverse legend ‘break’ variety that doesn’t affect the RIC number in this case. RIC lists CONST-ANTINVS AVG, A-N, N-T, T-I and I-N as the range of legend breaks

My examples of Alexandria 17 and 18:

And an odd one, type generally as 179 but with reverse reading GLORIA AVG - LIB ROMANOR instead of VICTORIA AVG etc. Pure speculation, but perhaps indicates that 181 (emperor galloping) with legend GLORIA ROMANORVM was struck first and the die engraver realised halfway around that they had the wrong legend?

Examples of 177 and 179