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. A line of piers mounted on a low retaining wall, alongside a former tramway (NPRN527465), is said to have carried compressed air pipes for powering machinery in the adjacent mill (nprn 527460). The alignment is approximately 20m long SW-NE, comprising 6 piers, each approx. 0.8m square and 0.7m high, the retaining wall beneath, 0.5m high.
A.J. Richards, Gazetteer of Slate Quarrying in Wales, 2007, p 250.
Recorded as part of RCAHMW Uplands Initiative Project, W B Horton, H&H, 14/12/2012.