Siscia XXISIS nummus mintmark

[Heliodromus]

I just received this one, and quite pleased with it as a cheap $30 eBay pick-up.

RIC VI Siscia 110 S, c.300-301 AD

The main interest here is the XXISIS mintmark, and secondarily the L field mark. The type probably dates to late 301 AD, associated with Diocletian's currency revaluation, although the nominal RIC date is 300 AD.

Diocletian's Edict on Maximum Prices is well known, but unless you're an LRB geek you may not have heard of his associated currency revaluation that occurred just before. The two appear to have been planned together, nominally to reign in inflation, but perhaps primarily to reduce the cost of supplying the army and to boost treasury seigniorage!

The currency revaluation doubled the initial 294 AD face values of Diocletian's reformed silver and bronze currency (with the nummus now being worth 25 DC, and the PRR 4 DC), while the price edict attempted to convert those doubled values into doubled spending power by keeping prices fixed, since otherwise it would just have caused inflation. Since the coins themselves and material costs of coin production hadn't changed, the doubled face values also meant a huge boost to treasury profits.

We're used to seeing the ubiquitous XXI (20:1) marking on aureliani, but it's uncommon on Diocletian's nummi (which had a similar 20:1 bronze:silver composition), only occuring at Alexandria and Siscia, both at a date of c.300 AD. At Siscia this XXISIS mark immediately precedes the switch of reverse type from GENIO POPVLI ROMANI to MONETA AVGG ET CAESS NN featuring Moneta with scales, propagandistically touting the quality of Diocletian's coinage. Given the timing of this in conjunction with the currency revaluation and price edict, the message of the "XXI" at Siscia and Alexandria seems to be to emphasize the quality of the coinage and perhaps reassure that it hadn't changed. The revaluation had gone into effect in 9-301, and the price edict a few months later c. 11-301, so these XXI marks likely date to around that time too. It's quite common from Alexandria, but much less so from Siscia.

A second point of minor interest is the "L" field mark. Siscia used a variety of letters on these, perhaps issued in rapid succession if not at the whim of the engraver. The letters used were L, S, I and C, with RIC not offering any satisfying suggestion as to what they mean. One probably doesn't need to look too deep ... we later see Siscia using S and I as altar decorations on Constantine's VLPP type, and seeing S, I and C again here suggests they were just drawing from the letters of "siscia" (and had recently used a SISC mintmark). The "L" wouldn't fit into this pattern though. Perhaps L for "libra" indicating a weight standard (XX:I) being stated? Has anyone come across any other theories?

 

[Nerosmyfavorite68]

That's quite an interesting writeup.  I'm a bit lazy to look up the weights of the later Aurelianii, but let's say 3.3 grams (many were around that weight), for the sake of easy math.  If the late Antoninianus is 2 denarii at 3.3 grams and the reformed nummus is 25 denarii at 10 grams, that seems pretty inflationary to me.  The larger coin is 3.3 time heavier but is valued at c. 12 times the value of the Antoninianus.  That's assuming that the silver coatings of both type were commensurate, only varying by the surface area of the respective coins.

[Heliodromus]

17 hours ago, Nerosmyfavorite68 said:

That's quite an interesting writeup.  I'm a bit lazy to look up the weights of the later Aurelianii, but let's say 3.3 grams (many were around that weight), for the sake of easy math.  If the late Antoninianus is 2 denarii at 3.3 grams and the reformed nummus is 25 denarii at 10 grams, that seems pretty inflationary to me.  The larger coin is 3.3 time heavier but is valued at c. 12 times the value of the Antoninianus.  That's assuming that the silver coatings of both type were commensurate, only varying by the surface area of the respective coins.

It's not clear what face value the pre-reform radiates had, either after Diocletian's revaluation of 301 AD, or following his coinage reform of 294 AD. The best evidence of values after the revaluation seems to be the inscriptions discovered at Aphrodisias (western Turkey) in 1970, both a copy of the maximum prices, and the revaluation values... It's a very fragmented inscription though, and even the most complete restoration (see Karl Strobel reference below) has gaps.

The 301 AD post-revaluation values of Diocletian's new coin types seem to have been:

argenteus - 100 DC
nummus - 25 DC
PRR - 4 DC
PRL - 2 DC

Which had all been doubled from their initial 294 AD values of:

argenteus - 50 DC
nummus - 12.5 DC
PRR - 2 DC
PRL - 1 DC

The initial nummus value of 12.5 DC seems odd, but explains depictions of money bags marked 12,500 which would be 1000 nummi of 12.5 DC. Licinius would also later introduce a 12.5 DC base metal coin, so evidentially this "odd" value was not a problem.

There is ambiguity in the surviving Aphrodisias inscription fragments as to what the pre-reform radiate was then valued at, and whether that had changed (doubled) from before. Part of the inscription appears to refer to TWO coins of value 4 DC (post-reform radiate + pre-reform radiate?), but another appears to refer to a coin of value 5 DC which might be the pre-reform radiate. In any case the (entirely base metal) post-reform radiate (PRR) seems to have been 4 DC, both per the inscription and confirmed by the many prices at multiples of 4 DC in the price edict.

One copy of the price edict (i.e. 301 AD prices) includes bullion prices which were then 6000 DC/lb for silver and 50-70 DC/lb for various grades of "copper". So, a 100:1 silver:coppper ratio, with silver at 18.24 DC/g and copper at 0.18 DC/g. We can see that even at only 5% silver (XX:I) the bullion/metallic value of the nummus and pre-reform radiate were dominated by the silver content.

e.g. For the 1/32 lb (10.24g) nummus at 5% silver, 95% copper (ignoring tin/etc)

Silver content value = 0.05 * 10.24 * 18.24 = 9.34 DC
Copper content value = 0.95 * 10.24 *  0.18 = 1.75 DC

Clearly there was a big intrinsic value difference between a 5% silver billion coin such as the pre-reform radiate and a pure base metal one such as the post-reform radiate! Given a 294 AD value of 2 DC (way above intrinsc value!!) for the PRR, the 5% silver pre-reform radiate should have had a value at least double - so perhaps 4 DC or 5 DC (in either case unchanged by the revaluation), which would be more in line with the 10g nummus of same composition at 12.5 DC.

In either case after the revaluation the face vs intrinsic value ratios of the nummus vs pre-reform radiate were completely out of line and the pre-reform radiate would have rapidly disappeared.

I'm not very familiar with pre-tetrarchic coinage, so not sure when the pre-reform radiate had changed from it's "double denarius" value, but it seems pretty certain it no longer had that value after Diocletian's reform of 294 AD.

***

Karl Strobel - Die Aufwertung des Jahres 301 n. Chr. und ihre epigraphische Dokumentation in Aphrodisias (Karien)
Tyche vol 30 (2015)
https://tyche.univie.ac.at/index.php/tyche/article/view/5003

You can download the PDF (German), then use Google translate.

A more accessible source for english speakers is:

Antony Kropff - Diocletian’s currency system after 1 September 301: an inquiry into values
2017, Revue Belge de Numismatique et de Sigillographie (RBN)
https://www.academia.edu/39459045/Diocletian_s_currency_system_after_1_September_301_an_inquiry_into_values

 

Edited August 13, 2023 by Heliodromus

[Nerosmyfavorite68]

Most interesting!

[Nerosmyfavorite68]

If they had gone back to the original Augustan system, only making the silver denarius a pure, but lighter coin, pretty much like the siliqua, would that have worked better?

 

[Al Kowsky]

[Heliodromus]

I don't know if they had enough silver for that, and it certainly wouldn't have been as profitable for the treasury -  a much higher profit margin in a nummus than an argenteus. I think a large part of the problem was that government expenditures had increased a lot, especially due to the size of the army under Diocletian.

It's difficult to fully understand though. To modern eyes the price edict and (+ revaluation) were an inevitable failure since they didn't stop inflation, but not everyone agrees that was necessarily the main goal, even if it was the stated one.

 

[Nerosmyfavorite68]

How did the Sasanian realm manage to retain an unbroken line of silver coinage?  They had a lot of wars with Rome, as well as their share of nomad invasions.

[Heliodromus]

4 hours ago, Nerosmyfavorite68 said:

How did the Sasanian realm manage to retain an unbroken line of silver coinage?  They had a lot of wars with Rome, as well as their share of nomad invasions.

I don't know - good question!

Sasanian bronze seems to have been very scarce. I have this interesting fire-altar AE of Shapur II overstruck by Constantine (as an Antioch anepigraphic), but have never been able to even find a photo of the unadulterated coin!

Edited August 13, 2023 by Heliodromus

[Al Kowsky]

4 hours ago, Heliodromus said:

I don't know if they had enough silver for that, and it certainly wouldn't have been as profitable for the treasury -  a much higher profit margin in a nummus than an argenteus. I think a large part of the problem was that government expenditures had increased a lot, especially due to the size of the army under Diocletian.

It's difficult to fully understand though. To modern eyes the price edict and (+ revaluation) were an inevitable failure since they didn't stop inflation, but not everyone agrees that was necessarily the main goal, even if it was the stated one.

 

I think the minting of argentei was more for political propaganda & to help sell the idea of the new nummus. Argentei are very scarce compared to the nummi & very few argentei show serious wear, so they were probably stored & used more for backing the nummi. 

[Al Kowsky]

4 hours ago, Nerosmyfavorite68 said:

How did the Sasanian realm manage to retain an unbroken line of silver coinage?  They had a lot of wars with Rome, as well as their share of nomad invasions.

After Gordian III died Philip I was eager to conclude a hasty peace with Shapur I. Part of the peace treaty gave Armenia back to the Persians, & the Romans were forced to pay a huge indemnity of silver equal to 500,000 denarii. I'm sure much of that silver was converted to silver drachma 😏.