Before 1800 digging small reaching only surface based ore was the only technique available to the miners. In the 19th century mining changed and more than 20 adits enabled the workers to reach calamine up to 105 m below the surface. During this time the Schlangenberg-area was perforated like a Swiss cheese. More than 700 miners worked at the mining shafts. During this time calamine was spread in the whole area and the poisonous metals zinc and lead contaminated large areas.