Roman Lead Mines

Dr Graham Osbourne writes of the Lead Mining industry in Roman Risca

by G. O. Osborne
In the recently-published first volume of the Gwent County History series there are three references to Roman lead mines at Risca (Gwent).’ On page198, in the chapter, `The Romans: Conquest and Army’, there is a reference to the work of Boon who suggested that `the lead mines at the Draethen and Risca, 12km. and 10km. W. of Isca lay within the territorium (of Isca)’.2
This is repeated on page 207 in the chapter on `The Romans in Gwent’ stating that `the territory must have included the lead mines at the Draethen and Risca, respectively, 12km. and l0km. to the west of Isca, with which a settlement in Lower Machen was connected’. Again, fig. 8.2 on page 181, which maps `The Roman Forts in Gwent’, includes Risca (along with the Draethen) as Roman lead mining sites.
It is clear that the origin of the idea of lead mines at Risca is, in this case, to be found in Boon’s work, where he mentions these lead mining sites at the Draethen and Risca, and goes on to mention the discovery of Roman remains in 1852 during the demolition of the old church of St. Michael at Risca;’ this was recorded by Wakeman in a publication of 1855.° Boon concluded that these Roman remains were `probably those of a military bath-house’, pointing out that Wakeman had reported that `Roman iron or lead mining operations had been carried out in the vicinity’.
Risca (Gwent) lies on the southern edge of the south Wales coalfield where underlying geological strata outcrop on the surrounding hills. On Mynydd Machen, to the south of the outcropping coal measures, lie Millstone Grit formations characterised by drifts of conglomerate rocks (i.e. `The Devil’s Apronful’). To the south again, there is a narrow belt of limestone, in which there is a large quarry at Lower Machen and a smaller, disused quarry on the opposite side of the mountain, above Pontymister. This latter, the so called `Dolomite Quarry’, was once used to provide hearth linings for use in the `open hearth process’ employed in the former steelworks at Pontymister. Beyond this limestone band lie the Old Red Sandstone measures, to the south of Pontymister. Lead ore (galena or lead sulphide) is found in these limestone formations. Even today, thin veins of galena can be found in the old Dolomite Quarry. The ground just above is pitted with a series of hollows and the site is marked on the first O.S. map as a `lead mine’. Moreover, during the construction of a by-pass road at Risca, below Craig-y-Neuadd, a massive cavern and tunnel network was discovered, obviously part of an old lead mine.`’ Little has been published concerning this and there are no references whatsoever in local documents. The discovery of wooden rails suggests that working took place here in the pre-tramroad era.’