Three years of excavation has led archaeologists to previously undiscovered parts of the Great Ormes mine which have not been penetrated since prehistoric times. The workings were found when flood water washed away rubble, which had been used by the prehistoric miners to back-fill the tunnels to save the effort of bringing the waste to the surface.
The prehistoric miners followed seams of malachite, a green copper-bearing mineral in the limestone, creating a honeycomb of tunnels, some so small that only a child could have crawled up them to scrape out the mineral. The entrance is almost entirely filled with rubble, covered with white calcite deposited by dripping water.
Tony Hammond, a mining engineer and managing director of Great Ormes mines, discovered the tunnels when he was asked by the local authority to advise on the safety of a car park on the site. Most archaeologists believed the Great Ormes mine was Roman, but Duncan James, a local amateur, obtained a piece of charcoal from the mine which was radiocarbon dated to 1000BC.
Frank Jowett, resident archaeologist at the Great Ormes mine, said: 'The great size of the workings here is radically changing our ideas about prehistoric Britain. It used to be thought that metal was imported into Britain in the Bronze Age. Now we believe that copper was mined very extensively in Britain probably by the Beaker people who we think came to Britain as prospectors. Evidence is now being found of 15 or more prehistoric mines in Wales. Prehistoric mines have also been found at Alderley Edge, at Coniston in the Lake District, and at least two places in Ireland. It seems that between 2000 BC and 600 BC there was an important metal industry round the edge of the Irish Sea which gives a completely new perspective to our knowledge of the this era.'
Mr Hammond said: 'The prehistoric miners broke the relatively soft malachite with hammers and scraped it off with bone tools. They worked very carefully, avoiding the hard rock, possibly producing only a few kilogrammes of ore a day. Prehistoric mines are very important for understanding human history, because it is metal which provided man with really effective tools and weapons - and it was metal weapons which enabled national states to emerge in prehistoric and early historic times.'