The entrance is only about a metre high and five metres wide, forcing anyone entering to crouch, and the passage narrows further as it goes in, eventually reaching a width of around two and a half metres and a height of just eighty centimetres. What the ceiling reveals inside is particularly striking: smooth, concave surfaces on the hanging wall, the upper face of the excavated rock, which archaeologists associate with fire-setting, a technique in which fire was lit against the rock face to crack it with heat before the loosened material was hammered away. The floor inside holds a substantial rubble deposit, and when the mine was inspected in 1984, flooding had accumulated near the back wall, which remained unexposed to a depth of around five metres.

This mine is one of 31 that together form the Mount Gabriel Prehistoric Mining Complex, currently the most significant group of Bronze Age copper mines known in Ireland. The complex was studied in detail by archaeologist William O'Brien, whose 1994 monograph brought the full scale of the site to wider scholarly attention. This particular working, catalogued as mine 30 in O'Brien's system, was first recorded by a surveyor named Duffy in 1929, though it was subsequently missed in a later survey by Jackson in 1968. Access into the mine was arranged from the east side of the entrance, where thin stone slabs had been set upright, possibly as a threshold or lining. Outside, two spoil dumps survive, one just above the entrance brow and a larger one to the north, where the extracted material was deposited. Immediately downslope to the east, a stone maul was found, one of the rounded hammerstones used by Bronze Age miners to break ore-bearing rock, a tool type recovered at prehistoric mining sites across Europe.