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 large quarry pit is approximately 60m N-S by 30m and a maximum of 20m deep. Quarrying was on 2 levels, with extensive sheer sides. Slate was removed from the lower level by tramway tunnel (NPRN527462), and and from the earlier, upper level by a short tunnel (NPRN527473) and incline (NPRN527474).
Across the top of the quarry are iron rods of a former safety fence.
Recorded as part of RCAHMW Uplands Initiative Project, W B Horton, H&H, 17/12/2012.