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Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust. [1] [2] [3] In mineralogy, silica (silicon dioxide, SiO 2) is usually considered a silicate mineral rather than an oxide mineral. Silica is found in nature as ...
The silica cycle plays an important role in long term global climate regulation. The global silica cycle also has large effects on the global carbon cycle through the carbonate-silicate cycle. [43] The process of silicate mineral weathering transfers atmospheric CO 2 to the hydrologic cycle through the chemical reaction displayed above. [4]
[1] [2] [3] Carbon dioxide is removed from the atmosphere during burial of weathered minerals and returned to the atmosphere through volcanism. On million-year time scales, the carbonate-silicate cycle is a key factor in controlling Earth's climate because it regulates carbon dioxide levels and therefore global temperature. [3]
The carbonate that dissolved is therefore pulled out from the system while the silica precipitated recrystallizes into various silicate minerals, depending on the silica phase. [17] The solubility of silica strongly depends on the temperature and pH value of the environment [ 3 ] where pH9 is the controlling value. [ 1 ]
Silicate, or silicic acid (H 4 SiO 4), is an important nutrient in the ocean. Unlike the other major nutrients such as phosphate, nitrate, or ammonium, which are needed by almost all marine plankton, silicate is an essential chemical requirement for very specific biota, including diatoms, radiolaria, silicoflagellates, and siliceous sponges.
Permineralization is a process of fossilization of bones and tissues in which mineral deposits form internal casts of organisms. Carried by water, these minerals fill the spaces within organic tissue. Because of the nature of the casts, permineralization is particularly useful in studies of the internal structures of organisms, usually of ...
Equilibria involving hydrolysis of silicate minerals are difficult to study. The chief challenge is the very low solubility of SiO 4 4-and its various protonated forms. Such equilibria are relevant to the processes occurring on geological time scales. [7] [8] Some plants excrete ligands that dissolve silicates, a step in biomineralization.
Silicate carbonate minerals can be formed in limestone metamorphosed by heating from igneous intrusions. [1] Scawtite forms where the activity of calcium is high compared to H +. Spurrite forms in a limited range of calcium activity and high silica activity. [2] In magma, a carbonate rich melt is imiscible with a silicate melt. [3]