An L-shaped range of six quarry buildings within Chwarel Cefn Du quarry (NPRN 400667). The buildings are mostly ruinous but some walls survive to up to 1m high and the overall area measures 33m long by 13m wide. The buildings were probably miners shelters. Two further buildings located to the south of the L-shaped range are better preserved. The easternmost stands to 2m high, and is 4m by 4m in size with an entrance to the south and a blocked window to the west. A fireplace and niche are within the south wall and there is evidence of a pitched slate roof supported on reused narrow gauge rails. The second building is 4m by 6m in area and also has a fireplace and niche to the south wall with a large blocked window in the east wall. Its gable ends remain largely intact. Marked on the OS 1st Edition mapping. P.J. Schofield, OANorth, 27th June 2007
