Singrig slate quarry was located on the south side of the road from Llanllyfni to Talysarn. A small open pit working it was possibly never mechanised. The tipping area extended across the road by a bridge. It was not rail connected though this was proposed at the turn of the nineteenth century. Successive editions of early mapping suggest the quarry was not in continuous use.
Remains (in 1991) include dressing sheds and the abutments of the road bridge.
Sources:
D.Gwyn, Welsh Slate: the Archaeology and History of an Industry (RCAHMW 2015), p.150.
Ordnance survey County Series maps: 25-inch sheet Caernarvonshire XXI.9, editions of 1889, 1900 & 1917; six-inch sheet XXI SW/SE.
RCAHMW air photo: 945127/51.
A.J.Richards, A Gazeteer of the Welsh Slate Industry (1991), p.55.

David Leighton & J.Wiles, RCAHMW, 9 March 2015.