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. An inclined plane transported slate from a large quarry pit (nprn 527485) down to the level of the processing mill (nprn 527460). It is 5m wide and partly embanked, 220m long WSW-ENE, with a vertical descent of 58m. The surface is covered in thin turf, with a half-buried steel cable visible.
Recorded as part of RCAHMW Uplands Initiative Project, W B Horton, H&H, 18/12/2012.