These malachite specimens come from works those were carried out in the railroad called "Basque Y". During these works, some rocks containing this mineral were extracted. They show prismatic radial aggregates of deep green malachite with an exceptional brilliance. Crystals are flattened due to its growth in fissures. Some transparency could be observed. Its origin is due to alteration of the original chalcopyrite matrix, present as small but brilliant granules, accompanied by hematite. The fibrous shape, color and luster make them very aesthetic.