Malachite (Cu2(OH)2CO3, copper basic carbonate) from Artés. Malachite eventually appears as a prismatic acicular crystals of the monolithic system or, often, as patinas, powdery coatings or reniform or globular masses. It has a beautiful, characteristic green color, green streak and 3,5 – 4 hardness degree. Malachite is a source of copper and, after its beauty, it is used in jewels. In the district of Bages, malachite is located mainly in Artés, in the so-called red-bed copper mineralization. The mineralization process consists first in the washing (lixiviation) of copper ions with water and then their precipitation as sulfides when suddenly a reductor level was reached. Finally, the carbonatation of the sulfides turns the copper mineral to malachite and azurite. The process of malachite formation is the real interesting thing in Artés, rather than the size of the crystals or the amount of the deposit. Malachite can be found in Cabrianes (Sallent), Santpedor and Ferrerons (Moià) as well.
[photo Joaquim Sanz / Museum of Geology Valentí Masachs]