The mining heritage of Avoca is of significant geological importance. These mines are considered the most important mines in Ireland. Avoca was once the largest open-pit mine in the world, where rocks and minerals were dug and removed from a large open hole in the ground. The mining complex itself includes a tramway arch that is unique in Ireland. It was built from stones taken from the surrounding area. Mining here peaked during the 1700s, although it is possible that it occurred here as early as pre-Christian times.
The copper found in Avoca arrives at the surface due to a combination of processes. Hot liquids rich in minerals rise from cracks in the earth’s crust under the oceans. Contact with the ocean’s water causes these minerals to cool, harden and combine to form a copper mineral deposit on the seabed. Over time this builds into a copper layer. After many thousands of years other movements of the Earth’s crust push these deposits closer to the surface.
Glaciers played an important role in uncovering copper deposits. Before the last ice age, this area was covered by thick layers of soils and rocks. The movement of the heavy ice across this landscape removed these layers. This left much of the rock, and the copper deposits within them, exposed making the copper easy to see and mine.
The remains of Avoca’s mining heritage can still be seen in the spoil heaps, engine houses, ore bins, sealed tunnels, open pits, and unique tramway arch.