Tag Archives: All That Glitters

All That Glitters, Experiment 6 and final

So, as just described, almost my first academic action of 2016 – for that is how far in the past we are for this post – was to head back to Birmingham, freshly remobilised, to pursue what was supposed to be the last run of experiments in the All That Glitters project of which I have now told you so much. Since the last one of those posts was only a short while ago, I’ll not reprise the project plan beyond saying it was to try and find out what was in Byzantine gold coins besides gold using X-ray fluorescence spectrometry and we were finding it difficult to get beyond what was on Byzantine gold coins. Now, read on!

Gold solidus of Emperor Constantine VI and Empress Eirini, Barber Institute of Fine Arts B4599

Gold solidus of Emperor Constantine VI and Empress Eirini, Barber Institute of Fine Arts B4599, in XRF analysis sample cup

Since we now more or less had a working method established, if it could be called that (since it didn’t really work), we had decided that our original research goal, of spotting changes in the trace elements in the centrally-minted gold coinage of the Byzantine Empire, was beyond the technology, and we needed to work out what else we could do with the remaining machine time. At first we’d thought we wouldn’t have enough, now we had more than we knew what to do with… But the most obvious thing seemed to be to broaden our sample as much as possible. So, we selected more of the Barber Institute’s coins, taken from imperial reigns we hadn’t covered, extra denominations from ones we had and sets from other mints than Constantinople that we could compare to coins of the same emperors there, and we took them all over to University of Birmingham’s School of Chemistry over a period of four days, where we were as usual excellently looked after as far as they could manage, and we subjected them to analysis. In all of this we were hampered by the fact that results were basically hard to reproduce; in fact, this became so frustrating that when it became clear that we still had a dribble of machine time budget left at the end of these experiments, we set up one more to address that problem specifically, and that will be the last of these posts when I get so far. But for this one I can basically give you only a very simplified set of findings, some of which might address real questions if only we could trust our results, and then gently suggest that even what we did get might justify some careful conclusions, though they might not really have justified the labour. So: some late antique numismatic questions, as answered by the S8TIGER in January 2016!

Bruker S8 TIGER XRF analyser open for business

Our tool of analysis, the S8TIGER WD-XRF machine, ready for action

Our first question in this set of tests was about fractional denominations. Though the primary imperial gold coin was the famous solidus, the “dollar of the Middle Ages”, there were also small numbers of halves (semisses) and thirds (tremisses) struck, with slightly different designs.1 Were these actually struck from the same metal as the solidi? Our results, shaky as they were, suggested that the answer was broadly ‘yes’, at least at Constantinople and, as far as we could test, Carthage. The only place where we picked up any reasonably substantial difference was Syracuse, in Sicily, but we’ll come back to that…

Gold solidus of Emperor Maurice struck at Ravenna 582-602, Barber Institute of Fine Arts B2390

Gold solidus of Emperor Maurice struck at Ravenna 582-602, Barber Institute of Fine Arts B2390

Gold tremissis of Emperor Maurice struck at Ravenna 582-602, Barber Institute of Fine Arts B2391

Gold tremissis of Emperor Maurice struck at Ravenna 582-602, Barber Institute of Fine Arts B2391; note the different design

The other thing we were hoping to establish in this set of tests was variations between mints. I admit that I was cynical about this; as I think I’ve said before, it had sort of become clear that almost all the elements were shared, and that this made sense in a world where imperial coin was being sucked into Constantinople in tax from right across the Mediterranean each year, melted down and then returned to the world as new coins; the recycling should have mixed everything together over time.2 So the only place we had a hope of seeing such variation was in places where that centralisation was breaking down, and in fact, from very early on it had become clear that late coins of Syracuse were gold-poorer than their Constantinpolitan contemporaries, to the extent where the one of us who hadn’t loaded a coin, so didn’t know what it was, could still tell if it was a Syracusan one from its results.

Graph of gold content over time for Byzantine mints of Constantinople and Syracuse

A very rough Excel-generated graph of coins’ gold content over time for the mints of Constantinople and Syracuse, by your humble author

Some of that impurity was visible by eye, indeed, but we could pick it up from before that. Indeed, there are one or two problem cases where mint attribution is uncertain for such coins, and for one of those at least, we were pretty sure we could now partly answer the question.3

Powerpoint slide showing three tremisses of Emperors Leo III and Constantine V from different mints

This is a slide I’ve grabbed from a presentation I will come to tell you more about in Princeton, and it’s the one on the right that’s the undecided case; but its metal content is much more Italian than Constantinopolitan, and we might get further yet

Why Syracuse was allowed to run its coins differently is a separate question, since as far as we know it was still paying tax to the centre and its coins must have been detectably poorer there too, but maybe what we’re seeing here is actually proof that it didn’t pay tax; its small change, too, seems to have been treated in such a way as to restrict its circulation, and Rebecca Darley (I can take no credit for this thought) wondered therefore if Sicily was persistent suffering a currency drain to the East that these measures were meant to stop by deprecating the exchangeability of Sicilian money.4 It might have helped!

Scatter plot of silver content versus copper content of Italian-attributed Middle Byzantine coins

Scatter plot of silver content versus copper content of Italian-attributed Middle Byzantine coins, which is probably Maria Vrij’s work, though I don’t remember; it was certainly her idea to do it

But as it turned out, we could get one step further with such distinctions. One of the other enigmas about coinage in Byzantine Italy is that we’re not totally sure which issues belong at which mints. Syracuse’s particular characteristics become distinctive after a while, but there are a rook of issues which are tentatively attributed to Ravenna, Rome or just ‘Italy’ that no-one’s really sure about.5 We haven’t solved this problem, but we may have spotted something that will help with it. I say ‘we’, but just as I owed the previous point to Rebecca Darley, this one was thought of by Maria Vrij; I sometimes think my sole intellectual contribution to this project was mainly defeatism. Maria noticed that whereas the Syracuse coins were debased with both silver and copper, and thus maintained a ruddy gold colour even once quite poor-quality, the elemental profile we were getting from supposed Ravenna issues included nothing like as much copper. Instead, the Ravenna issues seem to have turned ‘pale’, being adulerated only with silver. In that respect, they were following the trend of the post-Roman West at large, but it also makes sense in its own terms: Ravenna issued silver coin, which Syracuse didn’t, so when they had to cut corners with the solidi it makes sense that it was the refined silver from the local coinage that went into the pot, while Syracuse was presumably using less processed metal with accompanying copper content.6 So that’s something that belongs to Maria to write up properly, but hopefully it won’t be as many years before that happens as it has already been since we found it out… I make no promises there, as we all have other priorities, but nonetheless, we did find stuff in these tests that people might want to be able to refer to, and I hope this write-up at least gives some basis to believe that!


1. If you want the basics on these coinages, you can do no better even now than consult Philip Grierson, Byzantine Coins (London 1982), where pp. 50-56 will cover you for these purposes. The catchphrase, though, comes from Robert Sabatino Lopez, “The Dollar of the Middle Ages” in Journal of Economic History Vol. 11 (Cambridge 1951), pp. 209–234, online at http://www.jstor.org/stable/2113933.

2. My picture of this process comes pretty much direct from M. F. Hendy, “Aspects of Coin Production and Fiscal Administration in the Late Roman and Early Byzantine Period” in Numismatic Chronicle 7th Series Vol. 12 (London 1972), pp. 117–139, which is clearer than his later treatment in Michael Hendy, Studies in the Byzantine Monetary Economy, c.300-1450 (Cambridge 1985), pp. 257-303.

3. The standard reference for such matters, Philip Grierson, Catalogue of the Byzantine Coins in the Dumbarton Oaks Collection and in the Whittemore Collection, volume three: Leo III to Nicephorus III, 717—1081 (Washington DC 1973), Part I, where the coins in question are listed under Leo III 18a.1 (the Barber’s specimen online here), 48 (the Barber’s specimen online here) and, maybe, 12, 13 or 42 depending on what the Barber’s specimen (online here) actually is; the metallurgy makes type 42 seem likely though!

4. On the relevant Sicilian small change see for basics Grierson, Byzantine Coins, pp. 166-168, but for a different view of what was going on with its currency see Cécile Morrisson, “Nouvelles recherches sur l’histoire monétaire byzantine : évolution comparée de la monnaie d’or à Constantinople et dans les provinces d’Afrique et de Sicile” in Jahrbuch der österreichischen Byzantinistik Vol. 33 (Wien 1983), pp. 267-286, repr. in Morrisson, Monnaie et finances à Byzance : Analyses et techniques, Collected Studies 461 (Aldershot 1994), chapter X.

5. Grierson, Byzantine Coins, pp. 168-171.

6. Ravenna’s silver is discussed ibid., p. 140, but for the bigger picture see Mark Blackburn, “Money and Coinage” in Paul Fouracre (ed.), The New Cambridge Medieval History volume I c. 500‒c. 700 (Cambridge 2005), pp. 660–674.

Chronicle III: January to March 2016

I’m sorry there was no blog last weekend. Frustratingly, the thing I spent that time on now isn’t going to work out, so I’m determined to make sure there is a post this weekend, and the post that is due is the next round-up of my academic life, which has now reached 2016. It has been five months since I posted the last of these three-month slices, and the only real consolation there is that it took me less time to get through those three months of blog content than it did the previous one, but we will hopefully still see further gains made as marking ebbs and the summer shapes up. Can but hope, eh? But meanwhile, here’s how it looked at the beginning of 2016 for your humble blogger.

Teaching

It’s not just tradition but also a reflection of the real state of life that the first item on the bill is always teaching. Actually, in the first half of 2016 I had a lower teaching load than I have had since or likely ever will at Leeds, given what they need me to cover; I was running one module, albeit a big one, and contributing bits to a couple of others. That said, the beginning of the semester was still a fairly steep learning curve, as the module I was running was an inherited first-year course called Empire and Aftermath: The Mediterranean World from the Second to the Eighth Centuries, and even my undergraduate study experience only previously went back to AD 284; I’d never done the second or third centuries before in any context, let alone one where I needed to show expertise. Thankfully I had the help of two postgraduates who’d taught the module before and that made everything easier, although I did also have to second-mark and observe those postgraduates so they were not solely a labour relief. It was all a fair bit of work, and it coincided with the early part of the excellent but intensive Palaeography: Reading Medieval Manuscripts that we put our MA students through, which has continuous assessment. Furthermore, Leeds has examinations on the first semester’s modules as soon as the students get back in January, so I was reading up for the new stuff and choosing manuscript images for palæography at the same time as marking these exam scripts, and by the time I was done with those the first palæography assignments were in, and they were only just back to the students by the time the first-years’ formative essays came in, alongside the second palæography assignments… and in general it seemed a long time before the marking stopped.

Wolfenbüttel MS Codex Guelfybertiani 13, fo. 6v

One that was set; can you read this? Come to Leeds and we’ll teach you! But if you want to know more independently, it is Wolfenbüttel MS Codex Guelfybertiani 13, folio 6 verso, and you can find out more via the link through the image

In between these I fitted a couple of workshops for an Institute for Medieval Studies module, Medieval Narratives on the Modern World, on European national origin myths and on the so-called Reconquista, but those were fun and much less work. And there were also personal tutorials to be fitted in, to which only half the students turn up but of course you must book the time anyway, and feedback meetings, and also joint care of a visiting Chinese Ph. D. student. I felt fairly busy. Still, looking back, I was not carrying very much and the next year would have been much harder if I hadn’t had this run-up.

Extra Labours

That must also be how I had time for the other things I was doing. In particular, having found out that there was this coin collection in the bottom of the Library, I had resolved to make it part of my teaching, and so one of the few changes I did make to Empire and Aftermath was to turn one of the seminars into a coin-handling session to try and get people excited about the reality of the period in their hands. I’m not sure how well that worked, though commendably both my postgrad assistants leapt at the chance to be able to say they’d taught with coins and did some crash-course Roman numismatics with me, which made me feel useful. More prosaically, in the state of the collection there wasn’t really a way to find out what there was to teach with except to inventory it, so I put aside my Friday afternoons for most of this period to inventory the medieval, Byzantine and late Roman coins and got through a fair few. Some day soon I will get round to sorting out the photographs I took of the cool ones…

Copper-alloy 40-nummi of Emperor Constans II overstruck at Constantinople in 641-642 on a coin of Emperor Heraclius, DOC II Constans II 59c, Leeds, Brotherton Library, uncatalogued

Here is one that perhaps only I could think is cool, a horribly-made copper-alloy 40-nummi of Emperor Constans II overstruck at Constantinople in 641-642 on a coin of Emperor Heraclius, DOC II Constans II 59c, Leeds, Brotherton Library, uncatalogued

There was also other stuff involving coins. Back at the Barber Institute the process of replacing me had unfortunately crossed with their normal exhibition schedule, so my humble effort, Inheriting Rome, was extended for a few months to give the new curator a chance. I got to see my thus-prolonged exhibition again because there were still two more sessions of the now-legendary All That Glitters project to do, about which I will tell you shortly, and of course back at Leeds this was also the time in which I started the wheels turning on the project that would become Unlocking the Winchester Cabinet. My head of department was actually concerned that I was going to spend all my time doing late antique numismatics and not the research on whose basis I’d been hired, which I didn’t see as a serious worry because, at this point, there was still time and I used it on stuff that was interesting and useful for others as well as for me.

Other people’s work

I was also at this point still managing to travel for seminars a bit, and I have a lot of notes from this period that I’m not really going to say much more about. The itinerary looked like this, though:

  • Katherine Cross, Dominic Dalglish and Robert Bracey, “Images, Relics and Altars: comparing material religion on the first millennium”, Earlier Middle Ages Seminar, Institute of Historical Research, University of London, 20th January 2016, to which I went mainly because Robert is an All That Glitters collaborator, but at this stage he was also busy with a project called Empires of Faith, which was doing the kind of cross-cultural comparison implied by their title here, with Katy Cross bringing early English Christian monuments like the Gosforth Cross to the table, Dominic Dalglish coming from the ancient Mediterranean world and Robert from Kushan India, but here talking as much about what made for valid comparison in this set-up as the actual objects. This was interesting but the results of the project can now be investigated on the web, so I’ll leave this one aside and move on to…
  • Hugh Kennedy, “ISIS and the Early Caliphate”, Centre for the Study of the Middle Ages Annual Public Lecture, University of Birmingham, 27th January 2016, to which I travelled down and which I thoroughly enjoyed, but which needs treatment together with…
  • Julia McClure, “A New Politics of the Middle Ages: a global Middle Ages for a global modernity”, Medieval History Seminar, University of Leeds, 3rd February 2016, also substantially about the way people were reading the Middle Ages into the situation in the Middle East at that time, but approaching it from a very different direction. So I’ll do a post about those two together.
  • I also made it down to London for Alex Rodríguez Suárez, “The Komnenian Emperors: a Latinophone dynasty”, Earlier Middle Ages Seminar, Institute of Historical Research, University of London, 11th February 2016, about the extent of the changes brought about in Byzantine court ceremonial under, especially, Manuel I Komnenos that would be attributed to Latin influence, which Dr Rodríguez wanted, I think rightly, to read as appropriation of ways to assert dominance over the new Latin lords in the Middle East, not an aping of their flashy chivalric habits as they have often carelessly been read. That seemed convincing to me but I don’t have much more to say about it, so on to a clutch of things back at Leeds, as follows:
  • Pat Cullum, “‘Looking the Part’: presentation and representation of clerical masculinity in late medieval England”, Medieval History Seminar, University of Leeds, 24th February 2016;
  • Esther Eidinow, “Seeing into the Future? Oracles and the Ancient Greeks”, Classics Seminar, University of Leeds, 25th February 2016, about ancient Greek stories in which oracles were tested before being consulted for real, pushing at the edges of our categories of rational and irrational, interesting and my first step in a plan to make friends with my counterparts in Classics and Ancient History;
  • Natalie Anderson, “Tournament Trappings: Textiles and Armour Working Together in the Late Medieval Joust”, Medieval Group Seminar, University of Leeds, 7th March 2016, the culminating presentation by one of our Ph.D. students then about to finish and very much a mature piece of work about the ways in which combatants in late medieval tournaments displayed and distinguished themselves, which was as much or more a matter of fabric as the armour that more often now remains to us.
  • Then, back to London again to see a big name, Philippe Buc, “Eschatology, War and Peace: of Christ’s Armies, Antichrist and the End of Times between ca. 1095 and ca. 1170″, Earlier Middle Ages Seminar, Institute of Historical Research, University of London, 10th March 2016, arguing for a change in the way that medieval people thought about the oncoming end of the world that occurred with Crusading, in which it becoming OK to kill for God was itself a sign of the end times, but one that could last for quite a long while, setting up the fight that would now go on until everyone was Christian and the End finally came. I remember this being fun and extremely erudite, but looking back over my notes I’m not sure what I have to add to that summary, so it’s back to Leeds for two more to close the season, the relevant items being:
  • Travelling the World: from Apuleius to the Icelandic Sagas, from the picaresque novel to travel literature, a more substantial seminar in Classics whose separate components were:
    • Regine May, “Travelling to the Land of Witches: Apuleius’s Golden Ass“, about Thessaly’s Classical reputation as a hotbed of magic and sorcery and how travel might thus lead you out of the known world in several dimensions, and
    • Ros Brown-Grant, “Encounters between the East and West in Fifteenth-Century Manuscript Cultures”, on pictures of Westerners meeting Easterners either in West of East as imagined by Western manuscript artists, usually for tales of betrayal where Greeks were concerned or conversion where Muslims were, sort of inevitably.
  • and finally, Ross Balzaretti, “Early Medieval Charters as Evidence for Land Management Practices”, Medieval History Seminar, University of Leeds, 16th March 2016, to which I would have gone even had it been further afield since Ross has been a supporter of mine for a long time and I am very interested in his work, but precisely because it’s quite similar to my own, I’m not going to do a detailed write-up here because it would look a lot like, “Ross’s charters say things like mine do!” It was good, but you can already read the same sort of thing here.

My Own Research?

So that brings us to the end of the timespan, and I have only promised three extra posts out of it this time, though actually there are also one news and two tourism posts that should also be fitted in there. But what is as ever missing is my own research. What was I working on in this period, looking back? Well, for one thing I was finishing revisions on the conference paper that nearly wasn’t, “A Problem of Concavity”; the final version of that was fired off into what became a suspicious silence in the middle of February 2016. After that I seem to have turned to the reading to support the revision of my venerable paper on early medieval crop yields, of which I’d done the bulk while still at Birmingham, and I had a new draft of that done in March, although, it would seem, not one I thought submissible; that was still a way off, and I now don’t recall why. But beyond that it’s hard to see what I was doing, and the conclusion has to be, I think, that despite the apparently light load I was struggling. I would build up academic muscle from here, and reluctantly trim back a lot of the activity above to make other things possible, but at this stage I was still enjoying being an established academic as I’d imagined it and seen it done by others, as well as reading a lot for teaching, and perhaps not getting that balance entirely right, in retrospect. I think, also, I still hadn’t actually worked out how to schedule research in a job that finally actually included that as a duty, but had structured time only for other activities. Actually accepting that it was a legitimate use of my employers’ time to read a book, after years governed by the next deadline, was still proving weirdly hard for me… Of course, I still was governed by the next deadline, functionally, but I was only letting others set them, wherein a mistake with future complications. Anyway, this story will be continued! But for now there’s enough queued up to write about, and this has already been a long post, so I’ll wrap it here and thank you for reading.

Chronicle II: October to December 2015

Somewhat to my surprise, I have now reached the second of the what-was-going-in-my-life round-ups I was promising to use as the anchor of the new blogging programme here at A Corner of Tenth-Century Europe, back in, er, February. It wasn’t supposed to take eight months to record what had happened in three, but as you’ll have observed there was a fair bit of hiatus and strife in there, and I hope that we can pick things up a bit now. There’s only one way to find out, anyway, and thus we now reach the point where I try and give some impression of my first semester employed at the University of Leeds. The first thing that needs to be said about that is that my new colleagues were absolutely lovely, and guided me through new offices and routines with cheerful generosity; it all unrolled a great deal more easily than it could so easily have done while I found my feet. To try and explain what I was actually up to, however, probably needs breaking down into headings, and the obvious ones would be teaching, what we might generally class as extra labours, seminars and similar, research work and, lastly, life more widely; I’ll say the least about the last, but it holds the rest together. So here we go. Continue reading

An awful lot of numismatists in Sicily, II

So, after that bit of numismatic self-congratulation, let me take you back for the last time to September 2015 and the town of Taormina in Sicily, where I was then one of many gathered for the 15th International Numismatic Congress. You’ve seen some of the local antiquities, heard about the first two-and-a-half days of papers and visited a local castle, now it’s time to return to the thick of the academic fray. But first, a party!

Party in the coutryard of the Palazzo dei Duchi di Santo Stefano, Taormina, Sicily

Party in the coutryard of the Palazzo dei Duchi di Santo Stefano

Indeed, the first thing on our calendar after descending from Castelmola and eating was not an academic session but a party put on by the Medieval European Coinage project, to celebrate its resurgence into activity since the previous INC in the form of the publication of the series’ volume on the Iberian Peninsula and the near-completion of that on Northern Italy (which, much though I often doubted it, has in fact now also emerged, something I should probably announce separately too).1 By now you may well not remember that I am a part of that project still, but I am, so I was there to share in the glory. There were speeches, there was a strictly limited quantity of free wine, but mainly there was a superb setting.

Medieval European Coinage authors by the Cambridge University Press stand at a party in the Palazzo dei Duchi di Santo Stefano, Taormina, Sicily

MEC authors Bill Day Jr and Martin Allen looking very relaxed by the Cambridge University Press stand inside the Palazzo

It was a good way to wrap up the day. The next day was the last day of papers, however, and with certain obligations among them, and so for once I was up and ready right at the beginning. Here’s how it all unrolled. Continue reading

All That Glitters, Phase 4

The times continue strange in UK higher education, as you may have seen. Many of us are on strike for what is now the third week, more of us than ever now, and the employers’ representatives appear to be refusing to negotiate in person and then changing their mind by Twitter overnight. I don’t know what may happen in the next 48 hours and of course in case classes happen, they all have got to be got ready on the few days when we’re not on strike, in case something is resolved that means we go back to work. But, what this does mean is that my conscience is pretty clear about blogging. Having taken my first steps down a new road in the previous post, it thus behoves me to look around myself and say, ‘What was I doing in July to September 2015 that I haven’t already told you about?’, and the answer to that is not limited to but certainly includes, ‘zapping gold coins with X-rays some more’. So this is about our fourth set of tests.

Jonathan Jarrett and a gold solidus with XRF machinery in the Department of Chemistry, University of Birmingham

Posed, obviously; I may look intrepid, but you have no idea how tightly I was holding that coin. It rolling under the machine would have spoiled several people’s day quite badly…

If you remember, where we were with this is that having got money to evaluate techniques by which we might be able to use X-ray fluorescence spectroscopy to measure the metal content of Byantine coins, with an especial eye on trace elements that might betray metal sources, we had fairly quickly established that the kind of portable machinery which we could bring to the coins in their museum wouldn’t tell us what we needed to know. So the working set-up for these experiments was now that, after having checked our insurance quite carefully, as soon as I could get into the Barber’s coin room of a morning I would remove from it about 100 g of high-purity gold in the form of 20-odd Byzantine and other coins, then University security would turn up (in theory) and transport me to the School of Chemistry (in theory). We would then do as much zapping as could be done, with at least two people present where the coins were at all times, before Security turned up again (in theory) in time to get me and the coins back into the Barber before it closed. And this time we did this for four days running. I won’t tell you how many ways this process could go wrong, but I haven’t flagged them all. But Chemistry were lovely and very generous both with expertise and with biscuits, and though we never had quite the same team there two days together it was all quite a good group exercise anyway. So, what were we doing this time and how did it go? The answer is a long one, so I’ll put it behind a cut, but do read on! Continue reading

All That Glitters, Experiment 2

Somehow my posts about me and my work—and that may not be what you’re here for but, you know, I like it—have got behind my seminar reports in such a way that they’re into February 2015 and I’m still in December 2014. Let me resolve some of that disparity by giving you a short report on the second day of experiments in the collaborative project I’m in for analysing Byzantine gold coinage by X-ray fluorescence, which was 14th December. (If you need background I announced this project ages ago here and dealt with some of our starting questions and the first day’s experiment here.)

Cover of J. O. Jeppson, The Second Experiment

Our results have so far not been this dramatic, but then, I’m guessing that our first experiment wasn’t quite as adventurous as this must have been

To recap, we had established that if our experiments were to tell us anything much about elements other than gold, silver, copper and maybe one or two other pre-determined elements, we were going to need not the energy-dispersive machinery we’d been using on the first day but the bigger, more expensive and, most importantly, immobile wavelength-dispersive machinery in the Department of Chemistry in the University of Birmingham, a machine called the S8 TIGER. I am only just able to describe the difference between these two analytic methods: in so far as I can, it’s to do with what is being used to pick up the energy given off by the things you’re bombarding with x-rays. The WD machinery includes crystal collimators that are sensitive to certain wavelenths of that energy, which therefore get picked up better, where the ED machines, which measure only in terms of intensity of signal, simply wouldn’t see such things among the massive gold return, as we had surmised. The WD machine also scans its samples in a vacuum, which eliminates interference from the air.

Bruker S8 TIGER XRF analyser open for business

The mouth of the TIGER yawning wide, with five sample cups waiting and one under analysis

On the other hand there are also problems with the WD machinery that don’t exist with the ED kit. For us the first of those was simply access; it’s nothing to do with the actual machinery except in so far as it’s immovable, but because we had to take the coins to the kit rather than vice versa, that meant arranging transport and insurance even on campus, and the transport repeatedly went wrong, which cut into our experimental time a lot. But, also, the ED kit works with narrow beams focussed on points; the WD machine scans its samples in masks such as the one below, of which the two sizes relevant to us were 5 mm and 8 mm, and those were therefore the only area sizes that we could analyse. Importantly, this also precluded examining coins at their edges or over piercings, because the sample has to fill the exposed area completely. This also highlights a problem with both ED and WD methods: non-homogeneity. If for some reason your coin had an odd tiny lump of platinum on its surface, say, the ED machinery would either miss it (in which case you’d never know) or find it and report a massive platinum signal (which would be misleading for the coin’s overall composition). The WD machinery, however, would factor it into the average, so that you wouldn’t necessarily realise that it was a coherent inclusion rather than a component of the main alloy. So there was plenty to worry about even if the machine worked perfectly.

Emperor Heraclius just visible on one of his solidi of Constantinople loaded behind an 8 mm mask for analysis in the Bruker S8 TIGER

Emperor Heraclius just visible on one of his solidi of Constantinople loaded behind an 8 mm mask for analysis

Anyway, we had our goals clear for this test. The first was to get our hands on the machinery and find out what the operational considerations in any further planning were, the results of which you sort of see in the musings above. Here I have to acknowledge the tremendous help and general goodwill of Dr Jackie Deans, official keeper of the TIGER, and Dr Adrian Wright, who had first let us involve the Department of Chemistry in the project and had helpful things to say whenever he dropped in. Our second priority was to run the same ten coins around which we’d built our first experiment on the S8 TIGER and see how the results differed from those on the ED kit. And as it turned out, our third one was to determine how we wanted to use the S8 TIGER, because as Jackie explained to us, it could analyse at three levels, a 2-minute cycle that would probably get us no more data than the ED machinery had, an 8-minute one which should do the job, and an 18-minute one which was the very most data it could gather. Adding 10 minutes to each analysis was obviously going to limit the number of coins we could actually analyse in any given timeframe, so we really rather needed to know whether or not it was worthwhile.

Gold solidus of Empress Eirini at Constantinople set up for analysis in a Bruker S8 TIGER XRF analyser

The rather different visage in gold of the Empress Eirini, likewise cruelly cut down to 8 mm of glaring royalty

And so what did we find? Well, this machine certainly had more to tell us. We were now getting returns in terms of many elements, at concentrations of down to parts per thousand or even less. This ineluctably meant a decrease in gold concentration reported, because there was now simply more data to fit into the percentages, but the overall picture of lots of gold, not much silver and less copper was still very apparent in the reported figures. What we hadn’t expected, and had now to deal with, was that copper wasn’t usually the third most detected element, and sometimes silver not the second: instead, we were seeing lots of calcium, silicon and sometimes aluminium beating them out. It seemed a priori unlikely that these were original metallic components of the coins in these quantities. That in turn implied that these elements had got into, or much more likely onto, the coins since striking, be that from use, preservation or anything else that might have happened to them. But, whatever they were, they also seemed to be more consistently detected on the long cycle than the medium-length one, meaning that we were going to need to use the long analysis to have any chance of consistent findings. So now we had two difficult questions to answer in setting up Experiment 3: firstly, what could we get done with less than half the scans that we might have hoped to do in any given day of experiments, but secondly, when we did, could we determine whether these results were merely contamination or do anything about that if they were? And these were things which we attempted to address in the New Year, so I’ll stop here for now.

All That Glitters, Experiment 1

Almost the last academic thing I did last year before breaking for Christmas was the first two sessions of a project that is now nearly finished, All That Glitters, announced here so long ago. It was so long ago that it might be worth reintroducing. Basically, by great happenstance one of my predecessors in taking care of the coin collection at the Barber Institute had run into two people at a conference who were presenting about the ability of the X-ray fluorescence (XRF) equipment their company, Bruker Industries Ltd., produced to do metal analyses. That predecessor, Rebecca Darley, also knew Robert Bracey at the British Museum, who had done work with XRF on the coinage of the Kushan Empire, and now I was in charge of the Barber’s coins. None of us are archæometallurgists and our knowledge of archæology and numismatics didn’t necessarily combine with the metals analysis expertise upon which we could call so as to somehow make a composite archæometallurgist out of us all, but Robert could borrow the British Museum’s handheld XRF scanner, Bruker had a new machine they wanted to test against real problems, the Barber is on the same campus as several much larger and more expensive machines also supplied by Bruker some of whose host departments proved happy to let us use them and to tell us about them; a project seemed obviously to exist in potentio and our task was to work out how to make it tell us something useful.

Bruker Industries Tracer IV handheld XRF analysis system

I’m not sure if this is the exact machine we were using but its resemblance to a phaser seems impressively reminiscent

It’s too early to say whether we achieved that, pending actual publication of our results and conclusions which we are even now working on writing up, but right from the beginning it was clear to us that before we could have any historical conclusions we would have to have methodological ones. This is because there are so many potential problems with XRF analysis, problems which not all publications using it consider, and when they do, consider most often for silver alloys rather than the high-purity gold we would be testing, that the first priority had to be not to find things out, but rather to find out what we could find out.1 Accordingly, our pilot experiments were designed to evaluate the machinery more than the coinage, and we started on the 3rd December 2014 when Robert brought the British Museum’s handheld scanner up from the British Museum, along with its calibration standard, and Mike Dobby and Colin Slater from Bruker brought in their new M1ORA energy-dispersive scanner and we put some coins through their x-rays.

A gold solidus of Emperor Anastasius I struck at Constantinople (in the Eta <i>officina</i>) between 492 and 507, Barber Institute of Fine Arts B0005

The first coin to go under, a gold solidus of Emperor Anastasius I struck at Constantinople (in the Eta officina) between 492 and 507, Barber Institute of Fine Arts B0005

We had chosen a test set of ten coins running from Anastasius I (491-518) to Constantine VI (785-797), with two coins for each ruler from the same mint and if possible, the same workshop of the mint (if that’s what officinae were), hoping that whatever results we might obtain would thus be internally secure against outlier coins from a bad day at the mint or similar.2 All of those got zapped on both sides with both handheld and the microwave-like M1ORA. Both of these use a spot beam, but with the M1ORA it’s possible to target it precisely, so we aimed for flat surfaces wherever possible.

Bruker Industries M1ORA XRF analyser at work in the Coin Study Room of the Barber Institute of Fine Arts, University of Birmingham

The M1ORA at work in the Barber’s Coin Study Room, with team members in eager attendance

The initial results of this made the handheld device look like much the poorer sibling, as its readings were extremely variable. Robert worked out, however, that this was related to how much of its expected sample it had been able to observe—this in turn probably down to surface relief but already we were into unknowns—and when the figures were all normalised to a notional 100% of sample they came out much more like what the M1ORA was seeing. The M1ORA was able to dump its readings straight into a laptop equipped with suitable software, and did this levelling-up in that software, so made things immediately clearer for us by automating that step, solely an issue of configuration but we still needed to be aware of it. I keep stressing variables and difficulties because I don’t want to imply that we were getting actual true results, but that said, once they were both talking to us in the same framework the message of the machines was pretty consistent: all these coins were being analysed as very high-purity gold, 97% or more, which is astonishingly high for any pre-modern metallurgy. However, other than silver and copper, which occurred in about the proportions one would expect (i. e. not very much and even less), the only other element that was consistently detectable was iron. That was in part a factor of what we had asked Mike and Colin to make the machinery look for but if you have to do that at all, there is obviously a restriction inherent in your question-setting…

A gold dinar of Sindh imitating a Persian dinar of Shah Shapur II (309-379), struck at an unknown mint and date, Barber Institute of Fine Arts S0073

So then for something rather different, a gold dinar of Sindh imitating a Persian dinar of Shah Shapur II (309-379), struck at an unknown mint and date, Barber Institute of Fine Arts S0073

The very high fineness was sort of what we might have expected, anyway, as it is roughly what earlier analyses of Byzantine gold coins by a number of methods have suggested.3 It still made me uncomfortable for its lack of variety, however, and so since we had run-time left in the day I started hauling other things out of the cabinets. These included two Persian gold dinars, of Shahs Shapur II (309-379) and Varhran IV (388-399), and the above piece which is pretending to be something like the former, as well as an Arab-Byzantine solidus from Carthage and some more Byzantine pieces. Mainly I just wanted to be sure that the machinery actually would report lower gold finenesses, and so it duly did, with the Persian pieces both lower (but not by the same amount) and the Sindh piece even less fine (which, to be honest, was already apparent in its colour, but that was why I’d chosen it). The Byzantine stuff, and the coins imitating that, remained high in the machinery’s estimation.

A gold solidus of the second reign of Emperor Justinian II, struck at Constantinople between 705 and 711, Barber Institute of Fine Arts B4464

Another part of the starting sample, a gold solidus of the second reign of Emperor Justinian II, struck at Constantinople between 705 and 711, Barber Institute of Fine Arts B4464

This bit was fairly unsystematic sampling, but it did give us some reason to believe that the machinery was observing something consistent with our expectations, and which therefore fitted into existing understandings of the early Byzantine gold coinage. That is circular, though, obviously! This and the likely effect on the readings of differences between the surface of the coins and their cores, because of both manufacturing factors and subsequent environmental exposure, meant that we weren’t willing (and still aren’t) to say that these figures are actually how fine those coins were. We also weren’t seeing a range of trace elements which we had expected on the basis of older work, and which might have suggested things about changes in metal supply and treatment that would potentially be historical evidence.4 So, while these machines might serve other people’s purposes, we ourselves were going to need some bigger kit. And that would be Experiment 2, about which I shall write in a couple of posts’ time. In the meantime, however, here is some shiny metallic blogging for the Christmas season and I wish you all a happy holiday!


1. Part of our problem was that so much of the literature about these problems was old enough to relate, potentially, only to a much more primitive incarnation of the technique. Nonetheless, Michael F. Hendy & J. A. Charles, “The Production Techniques, Silver Content and Circulation History of the Twelfth-Century Byzantine Silver Trachy” in Archaeometry Vol. 12 (Oxford 1970), pp. 13-21, William A. Oddy, “The Analysis of Gold Coins—A Comparison of Results Obtained by Non-Destructive Methods”, ibid. Vol. 14 (1972), pp. 109-117 and J. Tate, “Some Problems in Analysing Museum Material by Nondestructive Surface Sensitive Techniques” in Nuclear Instruments and Methods in Physics Research Part B Vol. 14 (Amsterdam 1986), pp. 20-23, all suggest that differences should be observable between surfaces and cores of coins and between methods that measure only the surface and those that measure total composition, and L. Beck, S. Bosonnet, S. Réveillon, D. Eliot & F. Pilon, “Silver surface enrichment of silver–copper alloys: a limitation for the analysis of ancient silver coins by surface techniques”, ibid. Part B Vol. 226 (2004), pp. 153-162, DOI: 10.1016/j.nimb.2004.06.044 and Vasiliki Kantarelou, Francisco José Ager, Despoina Eugenidou, Francisca Chaves, Alexandros Andreou, Elena Kontou, Niki Katsikosta, Miguel Angel Respaldiza, Patrizia Serafin, Dimosthenis Sokaras, Charalambos Zarkadas, Kyriaki Polikreti & Andreas Germanos Karydas, “X-ray Fluorescence analytical criteria to assess the fineness of ancient silver coins: application on Ptolemaic coinage” in Spectrochimica Acta Part B Vol. 66 (Amsterdam 2011), pp. 681-690, DOI: 10.1016/j.sab.2011.08.001, give some explanations of why that should be so. (I have to thank Dr Eleanor Blakelock for some of these and several other useful references.) All of these except Oddy and Tate were working with silver alloyed with base metal, however, and so another of the problems we have is in knowing how far the same applies to gold and if it does, whether if alloyed with base metals only or also with noble metals such as we expected to see. And the mess only gets worse from there…

2. Barber Institute of Fine Arts B0005 & B0006 (Anastasius I, Constantinople, officinae Eta and Iota), B2761 & B2762 (Heraclius, Constantinople, both officina Eta), B4384 & B4385 (first reign of Justinian II, Constantinople, former marked Theta), B4464 & B4465 (second reign of Justinian II, Constantinople, no control marks), B4598 & B4599 (Constantine VI and Eirini, Constantinople, no control marks).

3. Those earlier analyses being principally those gathered and conducted in Cécile Morrisson, Jean-Noël Barrandon & Jacques Poirier, “La monnaie d’or byzantine à Constantinople : purification et modes d’altérations (491-1354)” in Morrisson, Claude Brenot, Jean-Pierre Callu, Barrandon, Poirier & Robert Halleux, L’or monnayé I : purification et altérations de Rome à Byzance, Cahiers Ernest Babelon 2 (Paris 1985), pp. 113-187.

4. The kind of conclusions, indeed, that were coming out of ibid. and another study there, Jean-Pierre Callu, Claude Brenot, Jean-Noël Barrandon and Jacques Poirier, ‘”Aureus obryziacus”‘, ibid. pp. 81-111, albeit with a rather more variable sample of evidence!