Tatoo Train and Potrerillos Foundry: Awesome trip between Montandon and Potrerillos metric gauge line, in Diego de Almagro city (North of Chile). FERRONOR train loaded with copper concentrate from Llanta, with a maximum slope of 3.9% in this section, confronting the abyss and the danger, already soon get to Potrerillos foundry, and with its characteristic and complete black color seems a tattoo on the wall of the mountain.