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 small quarry probably dates to an early phase of working. It is a deep quarry oriented SW-NE, 10m square and with a depth of 8m to the main quarry floor. However, there is a further, cavernous pit cut into the floor, approx. 8 x 6m. At surface level there is also a linear cut into the bedrock 12m long ESE-WNW, 1.5m wide and 2-4m deep.
Recorded as part of RCAHMW Uplands Initiative Project, W B Horton, H&H, 19/12/2012.