There is no entrance portal, and almost no development of the hanging wall, the overhead rock face that typically defines the ceiling of a driven mine passage. The opening, barely a metre long and no more than about 1.9 metres wide at its broadest, was cut westward into a low outcrop along the upper edge of an east-facing escarpment. Drop off the southern or eastern side and you fall eight to ten metres. It is a tight, exposed, and oddly minimal piece of prehistoric industry.

Mount Gabriel carries one of the most significant concentrations of Bronze Age copper mines in Ireland, and this working, catalogued as mine 28 in William O'Brien's detailed study of the site, forms part of that larger picture. When surveyors examined it in 1984, draining the interior and clearing vegetation, they found no primary mine sediments remaining inside. What they did find was a spread of spoil material covering roughly 80 square metres on a relatively flat area immediately to the north-west of the opening, and along the south-western edge of that spread, stone mauls were exposed. Stone mauls are the rounded hammerstones used by Bronze Age miners to break and detach ore-bearing rock; their presence here confirms the working's prehistoric character even where the mine interior itself has been largely emptied or eroded over the millennia. O'Brien's research, published in full in his 1994 monograph on Bronze Age mining at Mount Gabriel, places this site within a broader pattern of small, shallow workings targeting copper ore deposits across the mountain's upper slopes, worked most likely during the second millennium BC.