Braich Slate Quarry is located on the lower south-west slopes of Moel Tryfan, to the south of Rhosgadfan. It was an open pit working, operated on a small scale from about the 1820s, with material probably being sent out via Cilgwyn (Nantlle). It was substantially developed in the 1870s when a mill was built, with water power for pumping, steam for pumping and haulage via a chain incline, locomotive working and a connection made to the head of the NWNGR Bryngwyn incline. Early attempts were made here to drill charge joles mechanically using a rotary drill in preference to hand drilling, in the 1850s. In 1882 output was 2614 tons when 124 men were employed. The quarry closed in 1911.

Sources:
A.J.Richards, A Gazeteer of the Welsh Slate Industry (1991), p.67-8.
D.Gwyn, Welsh Slate: the Archaeology and History of an Industry (RCAHMW 2015), 143 & 151.
Air photos: RCAHMW AP94-CS 1006 RCAHMW AP945129/50-1; 945130/60

David Leighton, RCAHMW, 12 January 2015