Halkyn was one of the largest and most important lead producers in Britain, producing over 21,000 tonnes of ore at the peak of production in 1934. Beneath the mountain, lies a vast network of shafts and over 62 miles of tunnels. Felt hats, candles and wooden buckets as well as more modern equipment and machinery remain underground, untouched for many years.
Surface veins were easy to exploit with just a few hand tools but, as the demand for lead increased, so did the efforts made to extract the ore, following the veins deeper underground. Fire was used to crack the rock until after 1700 when gunpowder was introduced. This enabled faster tunnelling but also increased danger. From 1878 it was replaced by ‘high explosive’ dynamite, which was more efficient and safer.
As the mines went deeper, flooding became a serious problem. During the 1800s Cornish pumping engines were used to force water to the surface but even these mighty machines had their limitations. Mining would probably have stopped on Halkyn if it hadn’t been close to the sea, allowing the driving of deep drainage tunnels. In 1875, The Halkyn Tunnel was driven from Flint under the mountain from a point 180 feet above sea level and used to drain many mines, allowing them to re-open and get back into production.
The deeper Milwr Tunnel was the ultimate solution, driven in from sea level, it enabled profitable mining to carry on despite the 1957 slump in lead prices. However, the continuing cheap lead imports took their toll and the last mine closed in 1987, ending almost 2000 years of mining on Halkyn.