The cover photo shows the Minera mines at the height of their production in about 1890. The mined ore was brought to the surface and processed at what are known as the "Dressing Floors" where the ores were treated to remove as much lead and zinc. The lead ore was sold to smelting companies for further treatment and a lot of the zinc was processed in the Zinc Smelter - the long low buildings - centre left of the photo. The waste from the dressing floors was tipped onto adjoining land and shows up as white and grey in the photo. Being in limestone the ore veins contained a lot of calcite, a mineral which gives the tips their white appearance. The waste tips still contained a lot of heavy metal lead, zinc and cadmium, and these metals were actively being leached out into the land and rivers. It was the risk of pollution from these heavy metals that led to the reclamation works being undertaken. The waste from the tips was buried and covered with an inert capping and then planted with trees shrubs and grassland.