Aluminosilicates weathering

An example of aluminosilicate weathering is the reaction of the feldspar albite to a montmor-illonite-type mineral... 

Maurice P. A., McKnight D. M., Leif L., Fulghum J. E., and Gooseif M. (2002) Direct observations of aluminosilicate weathering in the hyporheic zone of an Antarctic dry valley stream. Geochim. Cosmochim. Acta 66, 1335-1347. 

It is then apparent that the characteristic feature of aluminosilicate weathering is the fixation of hydrogen ions in the place of cations that are released. The source of the hydrogen ions has been left unspecified and A may be... 

The formation of clay minerals in stony meteorites exposed to solar radiation on the ice fields of Antarctica is attributable to the episodic melting of ice and snow in contact with meteorite specimens that are warmed by sunlight. However, meteorites that were still embedded in the ice when they were collected also contained aluminosilicate weathering products (Gooding 1986b Gow and Cassidy 1989 Gow 1990). Harvey and Score (1991) suggested that meteorites that were weathered while they were stiU embedded in the ice could be... 

Overall, weathering controls the chemistry of material that is transported into the sediment and that which stays behind in the soil. As an example, consider a general weathering reaction for an aluminosilicate (Stumm and Morgan, 1995) ... 

Humus/SOM enter into a wide variety of physical and chemical interactions, including sorption, ion exchange, free radical reactions, and solubilization. The water holding capacity and buffering capacity of solid surfaces and the availability of nutrients to plants are controlled to a large extent by the amount of humus in the solids. Humus also interacts with solid minerals to aid in the weathering and decomposition of silicate and aluminosilicate minerals. It is also adsorbed by some minerals. 

Clay mineral A layered aluminosilicate, such as kaolinite, dUte, chlorite, and montmordlonite. Most are formed by chemical weathering of rocks on land. 

Isomorphic substitution The replacement of some of the aluminum and silicon in aluminosilicate minerals by cations of similar ionic charge and radius. This usually occurs as a result of chemical weathering. 

In Goulded RF, Equilibrium concepts in natural water systems. Adv Chem Ser 67 161-172 Stumm W, Furrer G, Wieland E, Zinder B (1985) The effects of complex-forming ligands on the dissolution of oxides and aluminosilicates In Drever JI (ed) The chemistry of weathering. Reidel, Dordrecht, pp 55-74... 

Clays are layer silicates (phyllosilicates) of particle size less than about 4 pm, produced by the weathering of aluminosilicate rocks. Clay minerals fall roughly into two structural classes the kaolinite type, based on paired sheets of tetrahedral (SiC>44-) and octahedral [A10n(0H) g " or... 

Silicates Many complex aluminosilicates or silicoaluminates are found in nature. Of these, clay in more or less pure fomi, pure day, kaolintte, kaolin, china clay TLSvA102G or Al203.2,Si02.2TT20 is of great importance. Clay is formed by the weathering of igneous rocks, and is used in the manufacture of bricks, pottery, procelain, and Portland cement. 

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