How does a mine work? Processing Perhaps the best way to understand Dalradian’s project is to compare it to a hi-tech, highly regulated, precision-led quarry – only one that is based underground with some processing on the surface. There are six stages to Dalradian’s approach. The second is ‘processing’. Unlocking Tyrone’s Precious Metals Once the narrow veins or seams which contain Curraghinalt’s gold, copper and silver have been mined underground, the next step is to separate the valuable minerals from the extracted rock. This ‘processing’ begins underground before moving to the surface. One of the project’s guiding principles is to retain or return as much mined barren rock underground as possible. This is environmental good practice, uses less energy, strengthens the mine development and reduces the amount of rock that is stored above ground.