Measuring roughly a metre in length, 1.65 metres wide, and half a metre high, it is easy to dismiss as a natural feature of the hillside. But the evidence points to something far older and more deliberate: a copper mine worked not with iron tools but with fire.

The technique visible here is known as fire-setting, one of the earliest methods used to extract ore from hard rock. Miners would build a fire against the rock face, allow the heat to fracture the stone, then dislodge the loosened material. The worked face at this site, driven at roughly 270 degrees into the scarp, bears the characteristic marks of that process. What makes it unusual is the absence of the debris one might expect alongside such workings: no spoil sediments and no stone mauls, the rounded hammerstones typically used in Bronze Age mining to pound away at ore-bearing rock. This suggests either a very limited episode of extraction, or that material was cleared away at some point. The site sits approximately ten metres south of a related mine on the same hillside, and was catalogued by archaeologist William O'Brien in 1987 as part of a broader survey of the Mountgabriel complex, which is recognised as one of the most significant concentrations of early Bronze Age copper mining in Ireland. The wider Mountgabriel workings are thought to date to somewhere in the region of 2400 to 1800 BC, placing this small, scorched hollow at the very beginnings of metallurgy on the island.