Slate mill marked on the 1891 OS map, but shown as roofless on the revision of 1901. It is part of the earliest phase of working at Bwlch Cwmllan (401443). The building is of coursed slate rubble, 26m N-S x 15m. The walls stand up to 3m high but most are reduced; evidence for openings is visible in each wall. Against the S end is a wheelpit, 14m long and 5m deep. It is 1.4m wide, increasing to 2m wide at W (downhill) end. The tail-race is not visible. There is a blocked opening above, in the S wall of the mill. Abutting the N end of the mill is a former projection, probably open to the N side; its W wall is 2m long and 1.5m high, the E wall reduced to footings.
Recorded as part of RCAHMW Uplands Initiative Project. W.B. Horton, H&H, 16/9/2011.