Botallack Arsenic Labyrinths

The mine buildings on Botallack Cliffs are protected by the National Trust. Opposite the Botallack Mine counting house are two arsenic works. Also at the top of the cliffs are the remains of one of the mine's arsenic refining works.
Arsenic compounds were an undesirable contaminant in the tin ore, which interfered with the smelting process. The solution was to heat the ore to drive off the arsenic in the form of fumes. In the early days of mining this caused severe pollution of the surrounding countryside. However, the arsenic itself proved to be a saleable by-product, so the arsenic-containing fumes were piped through a maze of adits where they condensed on the tunnel walls. The maze of adits has partially collapsed. Halfway through the maze the tunnel passes over an arch to cross one of the entrances to the mine. At the end of the maze the remaining fumes rose up the tall chimney.

An interesting insight into Cornwall’s industrial past