Soil chlorites

It is apparent that once alumina in solution reaches a high enough level, any expanding phase will become what is called a soil chlorite. The alumina becomes non-exchangeable in the interlayer position of the structure. It... 

In sum, one can say that 14 8 trioctahedral brucitic chlorite is largely unstable in most weathering environments, but aluminous soil chlorites are common under acid conditions. The bulk of chlorite found in sediments is certainly detrital in origin. 7 and 14 8 chlorites can be formed from 50°C upward in temperature until above 100°C where 14 8 chlorite becomes one of the most common minerals in sedimentary rocks. 

Most of the chlorite-like material formed in soils is dioctahedral rather than trioctahedral. In the process of weathering, illite and muscovite are stripped of their potassium and water enters between the layers. In these minerals and in montmoril-lonites and vermiculites, hydroxides are precipitated in the interlayer positions to form a chlorite-like mineral (Rich and Obenshain, 1955 Klages and White, 1957 Brydon et al., 1961 Jackson, 1963 Quigley and Martin, 1963 Rich, 1968). Al(OH)3 and Fe(OH)3 are likely to be precipitated in an acid to mildly basic environments and Mg(OH)2 in a basic environment. The gibbsite sheets in the soil chlorites are seldom complete and the material resembles a mixed-layer chlorite-vermiculite. The gibbsite may occur between some layers and not between others or may occur as islands separated by water molecules. 

An experiment was conducted using a soil called SI, an illitic clay containing chlorite from Michigan. Two sets of data showd the results of permeation of the regular soil, first with water and then with pure reagent grade heptane. The heptane caused the hydraulic conductivity of the regular compacted soil to skyrocket. About 8% cement was then added to the soil. 

Alteration assemblages may include primary chlorite, illite, smectites, and/or kaolinite, and various primary and secondary iron oxides, carbonates, and sulfides (Fig.1), any one of which may serve as indicators of fluid composition. Lithologic geochemical surveys rely on an understanding of these patterns to vector towards uranium deposits. The interpretation of hydromorphic geochemical surveys, including lake and stream sediment, and soil, depends on the mobility of uranium and associated elements in the surface and near surface environment. 

Like chlorine dioxide, chlorite is a very reactive compound. Since chlorite is an ion, it vrill not exist in air. In water, chlorite ions will be mobile and may move into groundwater. However, reaction with soils and sediments may reduce the concentration of chlorite ions capable of reaching groundwater. For additional information about what happens to chlorine dioxide and chlorite when they enter the environment, see Chapter 6. 

No Other information was found in the literature about the releases of chlorine dioxide and chlorite (ions or salts) to soils and sediment. 

Chlorine dioxide is a very reactive compound and may exist in the environment for only short periods of time (see Section 6.3.2). Chlorine dioxide is readily soluble as a dissolved gas. However, chlorine dioxide can be easily driven out of aqueous solutions with a strong stream of air. The partition coefficient between water and C102(g) is about 21.5 at 35 °C and 70.0 at 0 °C (Aieta and Berg 1986 Kaczur and Cawlfield 1993 Stevens 1982). Transport and partition of chlorine dioxide in soils and sediments will not be significant. Chlorine dioxide is expected to be reduced to chlorite ions in aqueous systems (see Section 6.3.2.2). 

Like chlorine dioxide, the chlorite ion is a strong oxidizer (Rav-Acha 1998). Since chlorite is an ionic species, it is not expected to volatilize and will not exist in the atmosphere in the vapor phase. Thus, volatilization of chlorite ions from moist soil and water surfaces or dry soil surfaces will not occur. 

Because chlorite is an anion, sorption of chlorite ions onto suspend particles, sediment, or clay surfaces is expected to be limited under enviromnental conditions. Thus, chlorite ions may be mobile in soils and leach into groundwater. However, chlorite (ions or salts) will undergo oxidation-reduction reactions with components in soils, suspend particles, and sediments (e.g., Fe, Mn ions see Section 6.3.2.2). Thus, oxidation-reduction reactions may reduce the concentration of chlorite ions capable of leaching into groundwater. 

No information was located in the literature on the transformation and degradation of chlorine dioxide or chlorite (ions or salts) in sediment and soils. However, chlorine dioxide and chlorite ions should degrade rapidly in soil in an analogous manner to the reactions described in water (see Section 6.3. 2.2). 

No information was located in the literature on the concentrations of chlorine dioxide or chlorite (ions or salts) in sediments and soil. 

JOHNSON (L.J.), 1964. Occurrence of regularly interstratifled chlorite-vermiculite as a weathering product of chlorite in a soil. Amer. 

Barnhisel, R. I., and Bertsch, P. M. (1989). Chlorites and hydroxyl-interlayered vermiculite and smectite. In Minerals in Soil Environments, Dixon, J. B., and Weed, S. B., eds., Soil Science Society of America, Madison, WI, pp. 729-788. 

Trioctahedral clay chlorite is an abundant constituent of soils formed by the weathering of basic volcanic pumice and tuffs in North Wales (Ball,1966). The adjusted chemical analysis (29.35% Si02, 16.82% A1203, 4.42% Fe203, 15.08% FeO, 0.25% MnO, 21.54% MgO, 12.00% H20+, 0.54% H20 ) produces the following structural formula ... 

The X-ray method affords a reasonable estimate of the structural formula based on chemical data. Using X-ray data, Ball calculated the structural formulas for twenty-six weathered soil and vein clay chlorites from North Wales. Tetrahedral Al ranged from 1.0 to 1.7 which is similar to the values for chlorites in shales. Octahedral Fe ranged from 0.8 to 2.4, with all but two values being less than 1.6 these values are much lower than those calculated (X-ray) for shale samples but almost identical to the shale values based on chemical determination of the Fe content. 

Not only can trioctahedral chlorites form in soils but there appears to be relatively little difference in composition between them and chlorites in sediments. This indicates that the trioctahedral chlorites in sediments can not automatically be assumed to be detrital. 

Although partially organized dioctahedral chlorites form readily in soils, there are relatively few reported in sedimentary rocks. (More dioctahedral chlorites probably exist than have been recognized.) Swindale and Fan in 1967 reported the alteration of gibbsite deposited in Waimea Bay off the coast of Kauai, Hawaii, to chlorite but no data were obtained on its composition. Dioctahedral chloritic clays have been reported forming in recent marine sediments however, the identification is indirect and the interlayer material is relatively sparse (Grim and Johns, 1954). 

Vermiculite and vermiculite layers interstratified with mica and chlorite layers are quite common in soils where weathering is not overly aggressive. (A few references are Walker, 1949 Brown, 1953 Van der Marel, 1954 Hathaway, 1955 Droste, 1956 Rich, 1958 Weaver, 1958 Gjems, 1963 Millot and Camez, 1963 Barshad and Kishk, 1969.) Most of these clays are formed by the removal of K from the biotite, muscovite and illite and the brucite sheet from chlorite. This is accompanied by the oxidation of much of the iron in the 2 1 layer. Walker (1949) has described a trioctahedral soil vermiculite from Scotland formed from biotite however, most of the described samples are dioctahedral. Biotite and chlorite with a relatively high iron content weather more easily than the related iron-poor dioctahedral 2 1 clays and under similar weathering conditions are more apt to alter to a 1 1 clay or possibly assume a dioctahedral structure. 

---