Conservationists have completed a painstaking 200-hour clean-up operation at the Giant's Causeway, a UNESCO World Heritage Site in Northern Ireland, after tourists hammered approximately 10,000 coins into the natural basalt columns. More than 20 kilograms (44.1 pounds) of currency were removed from the crevices, which visitors are believed to have wedged in for luck or love.
The metallic coins corrode rapidly in the damp, salty environment, expanding and exerting pressure on the delicate stone structures. Specialist stonemason Nathan Morrow was employed to extract the coins, a process that proved time-consuming, with some taking over 20 minutes each to remove. Pliers were used for coins near the surface, while a grouting tool was needed for those lodged deeper within the rock formations.
Dr. Cliff Henry, National Trust nature engagement officer, noted that the coins' corrosive nature quickly makes it impossible to determine their origin or date. While some coins dated back to 1999, they may have been inserted much later. Approximately 95% of the extracted coins were either sterling or euros, with U.S. currency being the next most frequent. Unusually, an O2 top-up card was also found.
Despite the extensive clean-up, officials estimate that several thousand coins remain trapped within the joints of the basalt columns. Some are too deeply embedded to be reached, while others have rusted so severely that attempting removal could cause significant damage to the stones. Dr. Henry compared the accumulation to a "Penny Falls" arcade game, where new coins push older ones further into the gaps.
The main removal project concluded in June, but tourists have already begun inserting new coins. Dr. Henry reported removing an additional 42 coins recently, and regular checks and removals will continue. The National Trust initiated the removal project in May of the previous year, following a report from the Geological Survey of Northern Ireland that highlighted the physical and chemical impact of the coins on the rocks.
Modern UK coins, made with steel cores or nickel-plated steel, corrode at different rates, leading to expansion that can split the rock. Saltwater spray accelerates this process. The National Trust had previously warned that the removal effort could cost upwards of £30,000 and has since installed new signage and utilized social media to discourage visitors from inserting coins.
The National Trust is considering how the extracted coins might be used in an exhibition to educate the public about the damage they cause. The Giant's Causeway, composed of over 40,000 basalt columns, was formed by volcanic activity approximately 60 million years ago.