The entrance is just two metres wide, and beyond it lies a flooded working that has never been excavated. When archaeologists probed it, they reached three metres before stopping; the spoil mound outside, a broad circular heap measuring roughly 22 metres by 15.5 metres and covering around 275 square metres, suggests the mine runs considerably deeper than that. Around the eroded eastern edge of that mound, fragments of stone mauls, the hand-held hammering tools used by Bronze Age miners, have begun to surface.

This is one of 31 prehistoric copper mines that make up the Mount Gabriel mining complex, a grouping that represents one of the most significant concentrations of Bronze Age mining activity in Europe. William O'Brien, whose research in 1987 and 1994 remains the primary study of the complex, catalogued this particular working as mine 22. The mines on and around Mount Gabriel are believed to date to the Bronze Age, a period when copper ore was extracted by lighting fires against rock faces to crack them, then breaking the loosened stone with stone mauls rather than metal tools. The spoil mounds left behind are the most visible evidence of that process today, low swells of shattered rock and debris that read as almost geological until you look closely at what is embedded in them.