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 short inclined plane took slate from a quarry pit (nprn 527472) down to the level of the processing mill (nprn 527460). It is 25m long W to E, 3m wide and has some stones laid on edge visible in the surface, suggesting that it was once cobbled. The lower end is cut by a later tunnel (nprn 527462) which represents a later, deeper working of the same quarry pit.
Recorded as part of RCAHMW Uplands Initiative Project, W B Horton, H&H, 17/12/2012.