What makes the site particularly arresting is not the scale of what survives, which is fragmentary, but the oddity of what it contains: a small roofless magazine built to an unusual combination of forms, circular on the outside and rectangular within, with a pointed doorway facing south-east and walls nearly three-quarters of a metre thick. Magazines of this kind were used to store explosive materials away from the main working areas, and the battlemented parapet, decorative in appearance but also a practical safety feature designed to direct a blast upward in the event of an accident, gives the structure a curiously fortified look quite out of proportion to its modest dimensions.

The complex at Carrigacat and Milleen preserves several features typical of small-scale coastal mining from the 1800s. Adits, which are near-horizontal tunnels driven into a hillside or cliff to access ore or drain water from deeper workings, and vertical shafts punctuate the site alongside dividing walls and the accumulated spoil of extraction. A reservoir lies approximately 150 metres to the south, and near it stand the remains of two single-storey dwellings, likely housing for workers attached to the operation. What gives the site an additional layer of complexity is the presence, on its southern side, of the remains of a fish palace, a term used in Ireland for a shore-based facility where fish, typically pilchards or herring, were processed and pressed for oil and salted for export. The co-existence of mining infrastructure and fish processing on the same stretch of coastline speaks to the opportunistic, multi-industry character of 19th-century rural economies in this part of Cork, where communities drew on whatever the land and sea offered in combination.