Beautiful green-blue stained rocks are frequently found in stone walls at Bunmahon in southern Ireland. The small village was at one time home to a successful copper mining industry. The copper is thought to have formed 354 million years ago at the beginning of the Carboniferous Period but possibly even earlier. The village is now the centre of the Copper Coast GeoPark and has a lovely roadside rock garden illustrating the geological history of the area. The copper mineral chalcopyrite (copper-iron sulphide) occurs as veins in white crystalline quartz and alters to copper carbonate forms such as green malachite and blue azurite. Weathered stones show these colourful blue-green variants of the mineral, with the rusty patches representing the iron component. Stones of this composition are found in walls all around the area.