"Metals in any province were almost exclusively State property, and formed an important item in the provincial budget. In Britain, the principal metal product was lead, which sounds dull, until it is recalled that the only way of producing silver known to the ancient world was by cupellation from lead, and that the abundant British lead represents a by-product from silver extraction. In the Roman world silver was the most regular money of account, and the need for large quantities explains the rapid development of British lead resources, attested by the numerous date-stamped ingots, or pigs, of the metal. The Mendip mines were in production by A.D. 49, six years after the conquest, the Flintshire mines by A.D. 74, the mines of Nidderdale, Yorkshire, by A.D. 81. Ail these dated pigs, and most others, are from direct Imperial working, but some undated examples from Derbyshire, and one early but undated example from Flintshire, bear the stamps of lessees, ail Roman mercantile citizens. Rarer still, but again associated with the Derbyshire area, are the pigs of the Lutudarum Partners (socii Lutudarenses) which took the name from the principal centre in the mining district, perhaps Chesterfield, and dispatched pigs in large numbers by water to the Humber. The quantity of lead extracted from Britain was very great and the Romans were struck by the ease with which it could be mined. The elder Pliny refers to much open cast mining. But he adds a significant and curious fact, that production was restricted in favour of the Spanish market. This is one of the rare cases in which such artificial controls are known to have been applied, though similar action was taken to restrict vine-growing in Gaul.

Of working and organization very little is known. In the Mendips the principal centre was Charterhouse on Mendîp, where the remains of a mining settlement cover a considerable area and are graced by a small amphitheatre. An early pig from this area is countermarked by the Second Legion and this might suggest soldiers in charge of convict labour, for relegation to the mines was in the Roman world a form of penal servitude. But no evidence exists either way in the Mendips for the continuity of this practice, if it was in fact there applied. The Imperial stamped ingots continue until A.D. 164-9, though some are countersigned with private companies' marks, while another carries the name of G. Nipius Ascanius, a Roman freedman lessee, also known in Flintshire. After that they appear no more, and it may well be that the working of the mines was then delegated to the curiales or tribal council, or to private concessionaires. This at least became the practice in other important Roman mining areas. If so, it would certainly account for the abundance of late-Roman silver coinage in the Somersetshire area, since the curiales would be receiving a substantial percentage of the output, returned to them in the form of silver coinage. In the fourth century A.D. Britain was still famous for its metal output, and the quantity of pewter and lead objects belonging to the period bears witness to its copiousness.

In the earlier period of Imperial working there is some evidence for the export of Mendip lead. The pig countermarked by the Second Legion was found at St Valery-sur-Somme, while one occurs at Stockbridge (Hampshire) and two on the Solent. This suggests a traffic of consignments across the Channel and along the main arterial route to Southern Gaul or Italy. It is not likely, however, as the administrative fragmentation of the Empire developed, that this traffic continued brisk.

The earliest stamped pig associated with Flintshire is of A.D. 74 ; and, if the annexation of the area occurred in A.D. 61, there would be evidence for rapid exploitation, as in the Mendips. The Italian concessionaire, C. Nipius Ascanius, cannot be much later, since his countermark appears on a Mendip pig of A.D. 59. The centre of the actual mining seems to have been Halkyn Mountain, as today, while the mining settlement lay at Pentre Ffwrndan, one mile south-east of Flint, where pottery and coins suggest an occupation beginning about A.D. 70 and continuing until at least the close of the second century A.D. There is also some evidence, though it is not strong, for third-century exploitation at Meliden, at the northern tip of the Clwydian mountains, in the Talar Goch mine. It would be interesting to know whether this was the reason for the foundation of the adjacent military site at Prestatyn, on a then navigable coastal creek. The pigs from the Flintshire area are stamped Deceangl, for metallum Deceanglicum, the name surviving in the medieval district of Tegeingl and today in a deanery. This was the name of the tribe which the manuscript of Tacitus presents as Decangi, the metropolitan version of a name which must have seemed oddly barbarie to a Latin ear.

The next dated group of lead pigs is the small group from Yorkshire, which also carry the tribal name of the area, in the form Brig, for metallum Briganticum. They are found in the area between Nidderdale and Wharfe-dale, which was much exploited in later medieval times for lead also. The earliest dated example is of A.D. 81, exactly ten years after the Roman acquisition of the area. Another, of Trajan (A.D. 98-117), is imperfectly recorded from Pateley Bridge. It is probable that this was not the only lead-bearing area worked in Yorkshire. There is a good local tradition of Roman exploitation of the Swale-dale lead deposits, in particular the Hurst Mine; it is connected with a pig of Hadrian, unfortunately never recorded in detail.

The Derbyshire lead field is one of the largest and most productive in Britain. There is evidence for Imperial working under Hadrian, but in addition many undated pigs are stamped with the names of private lessees. The fact that these names have a first-century ring about them does not definitely exclude a later date. The Roman name of the field or its centre, was Lutudarum and appears also as qualifying the name of a private company, the socii Lutudarenses. At what stage, however, the socii occur or in what order they came in relation either to the individual lessees or the Imperial working, or whether, again, ail or any two were contemporary, is quite unknown. It may be observed, however, that the socii sent down their pigs in large numbers to Petuaria (Brough on Humber), either to their own warehouse or to local wholesalers. Yet another aspect of exploitation is the lead ore from stream deposits found in.the Roman fort at Navio (Brough on Noe), from which the district was in part policed. This implies a System of collection by natives for which the fort served as central depot. The whole picture in Derbyshire is thus a complicated one. The relationship of the varions elements is obscure ; the administrative centre of the field is not fixed, though it is named, and the duration of the exploitation is unknown. This makes the record tantalizing and leaves only an abiding impression of intensive activity in an area attractive to the Imperial agent and the commercial speculator alike. Hadrianic working of lead is also attested in south-west Shropshire, in the Shelve and Snailbeach areas. Here or in Flintshire the Twentieth Legion took some hand in organization of the mining, since it counter-marked at least one pig, found at Chalon-sur Saône and dated to A.D. 195. Beyond this, however, there is no evidence for later Imperial working, and it may be that the field was turned over to concessionaires or small lessees. It is, on the other hand, likely that the small but rich field on the eastern slopes of Plynlimon, under development during the second century A.D., was always worked by the military.

Military supervision was certainly exercised in the Alston lead-mines of south-west Northumberland, which were worked upon a smaller scale in the third century A.D. under the Second Cohort of Nervii. Stamped seals from consignments which reached Brough under Stainmore bear the name of the cohort and the legend 'metal(lum)'. It is likely that some of the produce also went north-eastwards to Corstopitum (Corbridge), where the mineral wax associated with the Alston veins has been found. The fort of Gaermote (Gumberland) seems to have been a collecting centre for lead from the adjacent fells. Another lead-mining settlement associated with the military is Machen (Glamorganshire), where a settlement and remains of workings have been observed. It need hardly be doubted that in the military areas there were other ven turcs of the kind, since the Imperial government came to develop local resources wherever possible. The pawky request of Nero's legionaries that 'commanders looking for silver should get their decorations in advance' would indeed have been out of date.

If the exploitation of lead may be regarded as of great importance both in itself and in relation to silver extraction, the copper workings of Britain were also of substantial value in themselves and in their relation to bronze, an alloy used in the Roman world for almost every hard-wearing purpose. The principal deposits of copper lay in the north-west, in northern Shropshire, Caernarvonshire, and Anglesey. The Shropshire deposit is centred at Llanymynech, where the cave from which the veins have been worked by galleries was apparently inhabited by the miners.

Similar conditions appear to have existed in the Caernarvonshire copper mines of Great Orme's Head, where inhabited caves have also been noted, and associated objects date the activity to the third and fourth centuries A.D. This cave dwelling again suggests labourers tied to the spot, whether they were slaves or convicts, but it seems that no smelting was donc on the spot, the ore being carried away for treatment elsewhere. The copper cakes found in Caernarvonshire are stamped with the names of at least two priva te companies; and this would support exploitation by slave labour, though it is not necessarily true for every mine or for every period. In Anglesey the picture is rather different. Here the principal mining area was Parys Mountain near Amlwch, though other activity is known, as at Aberffraw and Pengarnedd. But the copper cakes in the island are ail associated with native villages, as if the ore were gathered by native labour and smelted piecemeal in the villages for eventual collection at a central depôt. This would imply that the island, once the cuit centre of the Druids, was treated as a temple estate with a fixed tribute trans-ferred from the Druidical community to the Roman State. The mines will explain the continuing interest of the Romans in the fort at Caernarvon (Segontium) and the provision of a naval station in the harbour at Holy-head in order to protect the valuable raw material and its workers from pirates, or slave-raiders. It is significant that while there is no evidence for legionary occupation at Chester after A.D. 367, the Caernarvon fort was then re-occupied intensively, the occupation lasting until A.D. 383. Its cessation is connected in Welsh legend with not only the usurpation but the actual person of Magnus Maximus, in the guise of Maxen Wledig. Whatever the truth of the story, it at least coïncides with the archaeological facts and with the economie value of the copper deposits. It should be emphasized that these are the most northerly and the most important copper deposits exploited by the Romans in Britain. The Cheshire mines at Alderley Edge do not appear to have been worked in Roman times, though well known to prehistoric and medieval man. The yorkshire deposits at middleton tyas were too deep and too waterlogged and were only accessible after the advent of steam pumping-machinery".

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