Known locally as Carraig Chrócháin or St Crohane's Cell, the opening is driven 55 degrees into a west-facing scarp along a quartz-sulphide vein, narrowing from 2.2 metres at the entrance to 1.2 metres near the back, and reaching only 4.8 metres in depth. What makes the interior remarkable is the condition of the walls: the surfaces are streaked with green malachite mineralisation, and their smooth, polished, concave profiles suggest the possible use of fire-setting, an ancient technique in which rock faces were heated with fire and then rapidly cooled to cause fracturing. The upper reaches of the Behaghane river run just to the west, and from the entrance the ground opens onto a view over Cove Harbour and Kenmare Bay.

The site layers several centuries of activity into a very confined space. The mine almost certainly saw prehistoric use, and later industrial workings, including shafts and degraded spoil-dumps further along the same quartz vein, point to nineteenth-century extraction. Some of those trials may be connected to the ventures of Sir William Petty and the Kenmare Colony, whose industrial activities in the region are documented from the seventeenth and eighteenth centuries. By 1808 the primitive working had been repurposed as a forge. The religious association runs deep as well: the site is dedicated to St Crohane, patron of the parish, and formed a station on the turas, the traditional penitential pilgrimage circuit, of the Kilcrohane pattern, a three-day observance that began at the holy well of Toberavilla on 29 July. The pattern is now defunct. Both the antiquarian Charles Smith and the traveller Richard Pococke noted, in the mid-eighteenth century, a further tradition linking the cave to St Kieran of Seir, who was said to have composed his monastic rule within it. Two short, slightly curving drystone walls extend from either side of the mine-face, and a small slab resting on the eastern wall bears a deeply scratched linear cross on its upper surface, suggesting continued devotional use into the later period.