Transformation clay minerals

Mother G, Robert J-L (1986) Titanium in muscovites from two mica granites substitutional mechanisms and partition with coexisting biotite. N Jahrb Mineral Abh 153 147-161 Morandi N, Nannetti MC, Pirani R, Resmi U (1984) La mica verde delle rocce di contatto nelTarea Predazzo-Monzoni. Rend Soc It Mineral Petrol 39 677-693 Muller F, Drits VA, Plangon A. Besson G (2000b) Dehydration of Fe, Mg-rich dioctahedral micas. (I) Structural transformation. Clay Mineral 35 491-504... 

I) structural transformation. Clay Minerals 35 491-504 Muller F, Drits VA, Tsipursky SI, Plan on A (2000b) Dehydroxylation of F, Mg-rich dioctahedral micas (II) cation migration. Clay Mineral 35 505-514 Pavese A, Ferraris G, Prencipe M, Ibberson R (1997) Cation site ordering in phengite-3T from the Dora-Maira massif (western Alps) a variable-temperature neutron powder diffraction study. Eur J Mineral 9 1183-1190... 

Tomita, K. and Sudo, T. (1981) Transformation of sericite into an interstratified mineral. Clays Clay Minerals,... 

Metal oxides have a significant role in influencing physical, chemical, and biological properties of soils. They may exist as ciystalline minerals, as short-range ordered (SRO) mineral colloids, or as surface coatings on clay minerals and organic matter. Organic compounds influence the formation, transformation, and surface properties of these metal oxides. The SRO A1... 

Cruz M, Kaiser A, Rowxhat PG, et al. 1974. Absorption and transformation of HCN on the surface of copper and calcium montmorillonite. Clays Clay Mineral 22 417-425. 

Other examples of weathering reactions involving igneous silicates are provided in Table 14.1. In some cases, chemical weathering proceeds in a stepwise feshion in which one clay mineral can be transformed into another given fevorable environmental conditions. 

During this zone refining, the primary (igneous) rocks are transformed into secondary minerals. These include (1) clay minerals, such as phillipsite, chlorite, montmo-rillonite (smectite), saponite, celadonite, and zeolite (2) iron oxyhydroxides (3) pyrite (4) various carbonates and (5) quartz. These minerals form rapidly, within 0.015 and 0.12 million years after creation of the oceanic crust at the MOR. During these alteration... 

Cervini-Silva, J., Wu, J., Larson, R.A., and Stuck , J.W. Transformation of chloropicrin in the presence of iron-bearing clay minerals, Environ. Sci Technol, 34(5) 915-917, 2000. 

Primary minerals with low surface area (e.g., sihca minerals) and low reactivity mainly affect the physical transport of water, dissolved chemicals, colloids, immiscible (in water) liqnids, and vapors. Secondary minerals generally have high surface area (e.g., clay minerals) and high reactivity that affect the transport of chemicals, their retention and release onto and from the solid phase, and their surface-induced transformations. The sohd phase also can indirectly induce the degradation of chemical compounds, through its effects on the water-air ratio in the system and, thus, on microbiological activity. 

A heterogeneous natural system such as the subsurface contains a variety of solid surfaces and dissolved constituents that can catalyze transformation reactions of contaminants. In addition to catalytically induced oxidation of synthetic organic pollutants, which are enhanced mainly by the presence of clay minerals, transformation of metals and metalloids occurs with the presence of catalysts such as Mn-oxides and Fe-containing minerals. These species can alter transformation pathways and rates through phase partitioning and acid-base and metal catalysis. 

Surface-catalyzed degradation of pesticides has been examined in the context of research on contaminant-clay interactions. Such interactions were observed initially when clay minerals were used as carriers and diluents in the crop protection industry (Fowker et al. 1960). Later specific studies on the persistence of potential organic contaminants in the subsurface defined the mechanism of clay-induced transformation of organophosphate insecticides (Saltzman et al. 1974 Mingelgrin and Saltzman 1977) and s-triazine herbicides (Brown and White 1969). In both cases, contaminant degradation was attributed to the surface acidity of clay minerals, controlled by the hydration status of the system. 

Brown, J. M. Elliott, J. J. "The Quantitative Analysis of Minerals by Fourier Transform Infrared (FT-IR) Spectroscopy", from Workshop on Application of IR Methods to the Study of Clay Minerals, Clay Mineral Society, 20th Annual Meeting, October 1, 1983, Buffalo, NY. 

Fig.14.20 Effect of various clay minerals on the transformation of 2-line ferrihydrite to goethite and hematite at 25 °C and pH 5 after 16 yr as measured by the ratio of oxalate to dithionite soluble Fe (Feo/Fed) (Schwertmann et al.

Although many authors insist upon the sequential degradation of phyllosilicates, i.e., taking the same initial material and transforming it into the various types of expandable minerals in the weathering process, (Heaver and Jackson, notably) this is undoubtedly not the only mechanism by which these clay minerals are formed in soils and possibly not the dominant one. Studies on the weathering of granites and more basic rocks... 

DUNOYER DE SEGONZAC (D.), 1970. The transformation of clay minerals during diagenesis and low-grade metamorphism—a review. Sedimentology 15. 281-346. 

VELDE (B.) and BYSTROM-BRUZEVITZ (A.M.), 1972. Transformation of natural clay minerals at elevated temperatures and pressures. Geol. For. 

Birkel, U., Gerold, G., and Niemeyer, J. (2002). Abiotic reactions of organics on clay mineral surfaces. In Soil Mineral-Organic Matter-Microorganism Interactions and Ecosystem Health Dynamics, Mobility and Transformation of Pollutants and Nutrients. Violante, A., Huang, P. M., Bollag, J.-M. and Gianfreda, L., eds., Elsevier Science B.V., Amsterdam,The Netherlands, pp. 437 447. 

Wang, M. C., and Huang, P. M. (1989c). Pyrogallol transformations as catalyzed by nontronite, bentonite and kaolinite. Clays Clay Miner. 37, 525-531. 

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