The entrance is barely wide enough to crouch through, the tunnel extends only a couple of metres before widening slightly at the back wall, and the whole thing looks, at first glance, like a natural fissure. It is not. This is a Bronze Age copper mine, one of 31 such workings that together form the Mount Gabriel Prehistoric Mining Complex, a site that represents organised, repeated human effort to extract copper from the Irish landscape perhaps four thousand years ago.

What makes this particular mine notable, even within that remarkable group, is its unusual profile. Most fire-set mines, where prehistoric miners lit fires against the rock face to crack it through thermal stress and then worked the loosened material free with stone hammers, tend to follow a fairly consistent shape. Here, a local structural disturbance in the rock has produced something more irregular. The smooth, concave sidewalls are still visible and immediately recognisable as the signature of the fire-setting technique, but the overall form sits at an odd angle to expectations. When the mine was examined, the interior was dry and held a substantial undisturbed floor deposit, which had not been excavated. Outside the entrance, a much eroded spoil dump yielded fragments of stone mauls, the heavy cobble tools used to pound and grind the loosened ore. Three large slabs set along the approach path may have served as a deliberate revetment, a low retaining structure to stabilise the ground. William O'Brien, whose detailed fieldwork in the 1980s and 1990s produced the definitive study of the complex, catalogued this working as mine 25 in his monograph on Bronze Age mining at Mount Gabriel.

The mine sits on a prominent rock scarp north of the Schull reservoir, accessible on foot across open hillside. The spoil heap outside the entrance, though heavily eroded, is still visible, and the stone maul fragments recovered there connect the ground directly to the people who once worked it, quietly and without ceremony, into the mountain.