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 winding house oriented E-W is at the top of an inclined plane (NPRN527475). It measures, 5.5m E-W x 4.5m. It has N and S walls of dry-built rubble stone standing up to 1.5m high. Linking them is a low wall on the uphill (W) side, 0.5m wide. The E end of the structure is battered and of rock-faced stone. The drum would have been set within an opening 2.9m wide, but all the parts have been removed. At the E end of the N wall, is a wall 3.5m long and up to 0.7m high running N, perhaps the remains of a workmen's hut. The structure is shown as roofed on the 1901 OS map.
Recorded as part of RCAHMW Uplands Initiative Project, W B Horton, H&H, 18/12/2012.