Rhos Quarry is located to the south-east of Capel Curig, just inside enclosed land on the south side of the Llugwy valley above Pont Cyfyng. A large pit working which made extensive use of water power, it opened in the 1860s. In the beginning material was trammed out of the working via a short tunnel - which was later opened out as a cutting - to the nearby mill area. As work progressed downwards a water-powered haulage system was used employing a 30 ft wheel which may also have pumped. Additionally there was an 18 ft wheel at the mill which might have supplemented the larger wheel when the mill was extended to twice its original size. The later cutting of a drainage tunnel allowed the use of a water balance and provided a ready exit for waste. This was consolidated into a platform incorporating a wheelpit, the intention being to build a mill at a lower level to avoid uphaulage. In 1935 the railed water balance was replaced with a chain incline, powered by a water wheel (inserted into the main mill wheel supply) and which was reported as appearing more primitive than those installed eighty years earlier; the last plant driven by a water wheel to be installed. The mill contained at one time 22 Greaves saws, a planer and some mechanical dressers in the gwaliau. Locomotive power was used in the mill area, a De Winton operating from the 1880s to about 1930. Output in 1882 was 1285 tons with 45 men. In 1937-8 52 men were employed. The quarry finally closed in the 1950s.
Impressive remains of the quarry and associated buildings have survived. Also, the mill building and associated structures, and remains of the water balance structure, though the incline has been quarriedaway. The reservoirs in 1991 still held water.

Sources:
D.Gwyn, Welsh Slate: the Archaeology and History of an Industry (RCAHMW 2015), pp.77-8, 111 (Fig.96) & 150,
Ordnance Survey County series six-inch map: sheet Caernarvonshire XXIII NW, editions of 1891, 190a, 1916 & 1953.
RCAHMW air photos: 94-CS 0918-22; 945122/50-4.
A.J.Richards, A Gazeteer of the Welsh Slate Industry (1991), pp.79-80.

David Leighton, RCAHMW, 4 March 2015