The remains of Cook and Ddol Slate Quarry lie above and to the west of Llanberis. Extraction was by pit workings which operated intermittently from the early nineteenth century. It was one of the few in the immediate area to have a mill. Material was carted from the west of the site until the building of the Ffrdd incline (NPRNs 505740). Output is unlikely to have exceeded 1000 tons per annum; 631 tons were produced by 26 men in 1882. In 1898, 67 men were employed. The quarry closed in the early twentieth century.
Surviving remains include, reservoir (505734; 505752), remains of the tramways, incline and associated structures (40556, 505736, 505748, 505753), and ruined buildings (505735, 505741, 505747).
Sources include:
Ordnance Survey County series 25-inch maps: sheet Caernarvonshire XVI.7; editions of 1889, 1900 & 1914)
A.J.Richards, A Gazeteer of the Welsh Slate Industry (1991), 33-4.
