Mynydd y Waun is a small quarry marked on the 1816 Ordnance Survey drawing of 'Cader Idris', but disused by the time of the 1890 OS map. A quarry face is 15m long N-S and 10m high, which returns to the W at the N end for 6m. The exposed face is overgrown, whilst the quarry floor is part waterlogged and covered in reeds and heather.
Recorded as part of RCAHMW Uplands Initiative Project, W B Horton, H&H, 21/11/2012.
