Geotrail around Parys Mountain

Fully illustrated PDF

Welsh version

Explore the brooding multicoloured hill that was one of the world's largest copper mines. Dr John Conway and Dr Margaret Wood, GeoMon / Anglesey Geopark

Pictures: J. Conway, unless stated otherwise

Length: 2 miles

Time: 2-3 hours

Difficulty: moderate, crosses rough and hazardous ground; wear strong shoes and keep to obvious paths; avoid pools of contaminated acidic water.

Parking: Parys Mountain car park, [SH 436 905].

Starting point: The walk starts from the car park [1][SH 43722 90501] and follows the track through multicoloured mounds of mine waste passing stone-lined ponds. Copper ore was extracted by shaft mining originally and many of the mounds surround old shafts which are particularly dangerous; later the ore was excavated from two large opencast pits. The ore was roasted on site, hence the multitude of shades of red and orange from oxidised iron. Water leached copper from the mounds into the precipitation pits where scrap iron was thrown in to start the chemical process.

Walk towards the rock outcrop and viewing platform [2][SH 43896 90272]. The rock here is a silica rich volcanic rock, reminding us that the original geological structure was an under water volcano whose heat generated high temperature fluids which permeated the sea bed sediments and volcanic ash and impregnated them with silica and metals such as copper, lead, zinc, iron as well as a little silver. The viewing platform overlooks the 'Great Opencast' of Parys mine — further on we shall see the smaller pit of the Mona mine, Along the right hand side, one can see sedimentary rocks with very little signs of mineralisation.

Follow the path around toward ruined buildings [3][SH 44127 90161], offices and storehouses; note that the only real vegetation is around such areas where lime mortar keeps the soil pH high enough for plants to grow. Just imagine the hustle and bustle at the height of mining, with explosions in the pit, ore and waste being hauled up tracks or wound up by windlasses on wooden platforms overhanging the side of the pit, tools stored or sharpened in these storehouses, perhaps even a 'cabin' or snackbar for the workers.

The path [or several interweaving paths] head along the side of the Opencast — one winds down into the pit but is steep and slippery, take great care if you choose to descend. The best view of mineralised rock is seen on the big rock in the middle of the pit.

Following the path one comes to complexes of carefully built stone-lined pits [4][SH 44566 90376] & [5][SH 44912 90541] into which drainage water was channelled and metallic copper precipitated by a chemical reaction when scrap iron is dropped in. There are some amazing bacteria growing in what is really sulphuric acid — take care not to step in any of these pools.

Continuing around the hill a tall ruined building [6][SH 44836 90780] comes into view — the remains of a Cornish beam engine house built to pump water from Pearl Shaft, sadly the chimney fell down a few years ago. From this point you could leave this walk and follow the mine road down to Porth Amlwch, the route taken by the copper ore.

The path then climbs to the top of the "mountain" and another tall building [7][SH 44540 90641], this time a windmill powering the pumping machine at Cairns Shaft, believed to be unique in mining history. It was near here that the copper deposit was first discovered in 1768.

The path winds back down to the car park, giving excellent views out over the north of the island, and particular towards the most recent mining activity, a shaft sunk in 1988 by Anglesey Mining Company; old mines never really die, there is always hope and jobs would be invaluable in this area... or maybe it's just a dream, some would say a nightmare.

Whatever your views, Parys Mountain is an important part of the island's heritage and former economy, once controlling the world price of copper, and some would say winning the battle of Trafalgar by "copper bottoming" Nelson's fleet. Visit the Geopark Centre and Heritage Museum in Forth Amlwch for more information.

Figures

See PDF

Route map. Geotrail around Parys Mountain.

Silica rich volcanic rocks.

View of workings at Parys Mountain.

Pearl Engine House, sadly in need of restoration [6].

Close view of the rock surface.

Ponds for the precipitation of metallic copper from mine water [4].

View to the "new" shaft sunk in 1988 showing the mine is not dead yet! [1]

The great Opencast seen from the viewing platform [2].

View of workings at Parys Mountain.