Studying Coin Pellet Mould

A short introduction to coin pellet mould by Mark Landon

Coin pellet mould has been found across Europe north of the Roman Empire, from Štaštín near Bratislava in Slovakia to Scotch Corner in North Yorkshire, England. It can best be characterised as trays of clay in which holes have been made. The holes range in diameter from 4mm to 20mm, and a tray will carry anywhere from 25 of the larger holes to 100 of the smaller. While it is undeniable that pellet mould was used in a process involving molten metal, it has been disputed that the pellets made in it were entirely, or even primarily, destined to be made into coin. Several writers, perturbed by the many finds of CPM in contexts generally considered ‘Early Roman’, have advanced claims that the main purpose of the mould was to produce pellets of similar weight and composition for use in general metal-working. At present, however, neither the physical evidence nor the theoretical basis is sufficient to support these ideas.

The current consensus is that unmelted metal fragments were placed in the holes: pre-mixed bronze, a much smaller fraction of silver, and occasionally an even smaller proportion of gold, so that alloying took place actually ‘in the cup’. The tray was then heated to cherry-red on top of the furnace, and then, by means of a tuyère, the contents of each hole brought very swiftly to the temperature at which fusion would occur. Because the pellets are essentially base metal, and because the clay has a significantly lower melting point than the metal, and despite the fact that a steady jet of oxygen-rich air must be played directly over the hole, if reducing conditions are not rigorously maintained the oxides that form on the surface of the molten pellets fuse irretrievably with the glassy phase of the clay mould. It is a tribute to the consummate skill of the Iron Age smiths that fewer than 10 trapped pellets have ever been found, a minute fraction when compared with the hundreds of thousands of successful pellets.

Landon Fig 1
Fig. 1 – Partial apex of a Verulamium-form 50 hole tray from the Puckeridge assemblage

Making a Mint is the product of the first major comparative study of coin mould as an artefact in itself. Previous studies had relied on very small samples and did not use a consistent recording protocol, meaning that detailed comparison even within a single study was not possible. Furthermore, the primary focus had been on testing for metal residues, seeing the moulds as adjuncts rather than as artefacts in themselves. In the course of the work leading up to the book, nearly 50kg. of coin mould was examined and recorded using an exceptionally detailed protocol, thus enabling assemblages from across England to be compared very closely, and the findings then compared with the results of several series of experiments in coin mould manufacture.

Landon Fig 2
Fig. 2 – Edge fragment from Bagendon with 7mm – 8 mm base diameter holes

Although pellet mould from different sites is superficially similar, close study reveals that variability is a salient characteristic. In fact, it is perhaps wise to think of the manufacture and use of pellet-mould as a family of closely-related techniques. This variability extends from the fabrics, through the methods used to make the trays to the way in which they were used. It has been assumed that it is possible to deduce pellet module from either the diameter or the volume of mould holes on a fragment, but an examination of more than 11,000 mould holes demonstrated conclusively that this is not so. Variation in these parameters, from site to site, from assemblage to assemblage, between fragments and between the holes on single fragments, show an absence of standardisation which means that the holes could not have been used to measure the metal they contained.

Landon Fig 3
Fig. 3 – 17mm base diameter holes from Ford Bridge, Braughing

A major aim of the study has been to discover more about the social and economic context for pellet manufacture. Hints have been found in several of the assemblages studied for the season in which the coin mould was made. Chance impressions, mostly on fragment bases, of grass seed-stalks and of cultivated grains, suggest that the minting process often began in late summer or early autumn. This is exactly what one might expect from an agrarian society, because it is after harvest that there is time available for activities not directly related to farming, and it is also at this time that such a society is at its wealthiest. This is particularly important at those sites, such as the Braughing/Puckeridge settlement complex, where there is evidence for more than one episode of minting, because it locates minting in the broader cycle of  life in these places.

It has been demonstrated very well by Haselgrove and others that European Late Iron Age coin had value over and above the purely monetary, so it is perhaps no surprise that the study found clear evidence that coin pellet mould also had significance on more than one level. The majority of deposits of coin mould in England are very small, ten fragments or fewer, and they are often accompanied by fragments of expensive pottery and the remains of feasting. This is mirrored by the undeniable fact that the larger assemblages show clear signs of the preferential removal of parts of trays. Although trays were often manufactured without a great deal of care, after use it would seem that they took on some of the numen of the coin they helped to produce. There is evidence that some , at least, of the larger assemblages were exposed to the elements for some time before finally being deposited in pits or ditches, raising the possibility that they may have been displayed in the open as symbols of wealth and prestige.

This blending of the practical with the mystical is perhaps adumbrated by the three tray sizes so far attested in England: 25 holes, 50 holes and 100 holes. The capacity of the tray seems to have been dictated by the diameter of hole to be accommodated, the largest holes being found on trays with the smallest capacity. There is a good, practical reason for this: the larger the tray, the more flimsy and susceptible to breakage it becomes.

Landon Fig 4
Fig. 4 – Reconstruction of a Verulamium form tray

However, the way in which holes are laid out on the two known types of 50-hole tray, as 7 rows of 7 holes, plus a single hole above the top row to make 50, appears to show that to the makers and the users of the trays, square numbers had a significance above and beyond the purely practical. It is possible to demonstrate that the portion of the pentagonal 50-hole Verulamium form tray proportionately most likely to be selected for removal from a larger assemblage was the apex of the pediment, with its single hole.

Landon Fig 5
Fig. 5 – Verulamium-form pedimental apex from Ford Bridge, Braughing, showing incised line

That the pedimental apex hole is often separated from the body of 7 x7 holes by a line adds to the idea that it was regarded as ‘special’, although we can never know whether it was regarded as ‘lucky’, or as ‘dangerous’. The picture that emerges is of a process made deliberately complex, taking place within a society which had a very complex and multiform view of value, where an object could unite utility, kudos in display and spiritual worth.

Since Making a Mint was written, another three major assemblages have been examined – Blackfriars, Leicester; Scotch Corner, North Yorks; BRR16, from Braughing in Hertfordshire.

This last assemblage is still in the process of being examined, but it is already clear that it is of the greatest significance. The Braughing/Puckeridge settlement complex has now yielded around 70Kg. of coin pellet mould in total, and it is clear from stray surface finds that more assemblages remain to be uncovered in the vicinity. Braughing/Puckeridge is therefore one of the most significant sites of pellet-mould deposition in Europe, and in conjunction with Jake Morley-Stone of the Liverpool University Archaeomaterials Department – with funding from Historic England – this new material will be subjected to the most comprehensive programme of analysis yet undertaken.

Landon Fig 6
Fig. 6 – BRR16: Coin mould pavement

In all, 28kg of coin mould was retrieved as a single deposit, and preliminary examination has revealed new tray forms and new methods of tray manufacture. While none of the major conclusions of Making a Mint has been challenged, the BRR16 coin mould does seem to make necessary the modification of some of the positions adopted. Furthermore, given the sheer variety of types in the assemblage, the different fabrics, tray forms and techniques,  it is difficult not to consider the intriguing possibility that coin mould is being brought together at Braughing from many different places in an echo of the Folly Lane burial mound, where each turf can be shown to have come from a different location. Some of the BRR16 coin mould shows strong similarities with an assemblage found at Bavay, Département du Nord, France, and only further research will be able to demonstrate whether this resemblance is significant or merely fortuitous.

Landon Fig 7
Fig. 7 – Coin mould with square holes from the BRR16 trench, Braughing

All of these matters – and many others, including the recent discovery of a structured deposit which includes coin mould – will receive thorough treatment in the book The Mints of Braughing by Jake Morley-Stone and Mark Landon (forthcoming, Archaeopress).

9781784914080Mark Landon’s Making a Mint is available now in paperback (£34) and PDF eBook (from £16 + VAT) from Archaeopress. Order online at at the special price of £27 (20% discount) until 31/05/2017.

Making a Mint Comparative Studies in Late Iron Age Coin Mould by Mark Landon. Printed ISBN 9781784914080. Epublication ISBN 9781784914073. Book contents page

xii+198 pages; illustrated throughout in black & white.