This is the largest of the North Wales copper mines where mining appears to have been carried out over a long period though the visible remains date largely from the eighteenth century onwards. The site is dominated by two large opencast pits (the Parys (NPRN 300166) and Mona (NPRN 300167) pits) created initially through the collapse of underground workings accessed by shafts and levels. These pits, however, represent only a small proportion of the total workings. Shafts to extant underground tunnels have been capped. The windmill (NPRN 306041) on the summit and the Cornish engine house (NPRN 33670) are well-known landmarks though the commonest visible feature remaining (aside from spoil tips) are precipitation pits (e.g. NPRN 33753). Other structures visible on the mountain include the Mona mine yard, remains of cobbing floors, reservoirs, leats, whimseys and engine houses.
Copper ingots with Roman inscriptions have long been known from the vicinity of Parys Mountain, and a Carbon14 date from charcoal from the excavation of a spoil tip (in the 1980s) has led to claims for an Early Bronze Age origin for these workings.
D.K.Leighton, RCAHMW, 8 September 2004.