Parys Underground Group / Grwp Tanddaearol Parys

Open cast

Copper was rediscovered at Parys mountain in the 1750s. Initially it was the Mona mine which was worked.  However within a few years the Great Open cast at the Parys mine was also being worked. The copper was a low grade ore but was cheap to recover due to the nature of the open cast working.  Towards the end of the 18th century Parys mine was the largest copper mine in the world.


This photograph shows the windmill in the distance. The large lake in the bottom of the open cast had built up over many years.
The removal of water from the mountain for safety reasons in 2003 has meant that the water has now been drained.
In the bottom of the Great Open cast is that massive structure which has been identified as the remains of what was once an underwater volcano or "Black smoker". It was this volcanic action which enriched the surrounding rock with so much mineral.

In  a number of places within the great open cast a series of deep drilled holes can be seen. These are called rock cannon. It was a tradition within the mine to celebrate important occasions by filling the holes with black powder and setting fire to it.  The load explosions would echo around the Great Open cast and be heard for many miles around.