The Lead Mining Process
by Tim Clarke
Finding lead-bearing rock
In the Ullswater Valley, minerals are found in veins running through Borrowdale Volcanic rocks at the head of the valley. The most important veins are of galena, a form of lead sulphide. Galena is often associated with other minerals, such as silver and zinc.
The first challenge for anyone wanting to remove a valuable mineral from a rock vein is to find the vein. Sometimes the vein is visible from the surface but if it is overlain by other materials these have to be removed. Sometimes, early miners used a ‘hushing’ technique, directing water held in storage ponds to flood over the veins and wash away the surface clay and alluvial material, making the ore-bearing veins accessible. In other places, 'leats' or channels were constructed to bring water to the veins. Sometimes the leats could be up to a mile from the vein itself.
Where the vein lies deep within the surrounding rock various techniques were used to reach it. The most common was to drive an ‘adit’ (tunnel) horizontally at different levels into the mountain side with the intention of ultimately hitting the vein and extracting the minerals from it. This could be a perilous and physically demanding task. Before you start digging, you have no idea how thick the vein will be. Many mining sites show evidence of miners driving tunnels into solid rock for 100 to 200 metres, only to reach a blind end, unable to find the vein.