Secondary minerals

SECONDARY MINERALS (EN: secondary minerals; DE: Sekundarminerale; FR: mineraux d'alteration, mineraux secondaires; ES: minerales secundarios; RU: вторичные минералы) are the minerals, which have been formed as the result of the chemical weathering, or of the replacement of the minerals, which have been isolated earlier.

The secondary minerals may be encountered often, especially within the superficial zones of the Earth's crust, where they are formed during the processes of the hypergenesis. The transition of the primary minerals into the secondary minerals is accompanied by the removal and exchange of the substance with the environment, and so on. The examples: the transition of the chalcopyrite CuFeS2 into the secondary bornite Cu5FeS4, the forming of the covellite Cu2SCuS, malachite Cu2[CO3](OH)2, and atacamite CuCl2•3Cu(OH)2 over the chalcopyrite, of the kaolin over the feldspar and mica, and so on.

The secondary minerals may also be formed in case of the single only physical change of the crystalline structure of the substance, with the preservation of its chemical composition (the cubic chalcocite transitions into the rhombic type, the cubic high-temperature leucite transitions into the rhombic low-temperature type, and so on). The secondary minerals form the powdery, flowstone, earthy, and other masses, the crystals, smears, and so on, or the pseudomorphs over the primary minerals. Many secondary minerals (especially within the zones of the oxidation, and within the iron hats of the ore deposits) have the important practical significance.