Minllyn is a slate and slab quarry (nprn 310049) begun in the C19, the most productive phase of which began after the Carlyle Slate & Slab Company was formed in 1872. Work ceased in 1924. The entrance to a slate mine is one of the earlier phases of working, which was superseded when the hill above was quarried out from the surface (nprn 527485). The mine entrance is 2.1m wide, but mainly buried under scree. Flanking and defining the entrance are drystone retaining walls, each up to 1m high. Outside the entrance, is a spoil tip (NPRN527499), the older part of which probably relates to this mine.
Recorded as part of RCAHMW Uplands Initiative Project, W B Horton, H&H, 20/12/2012.