Biotite-vermiculite

Kriegman-King MR, Reinhard M. 1991. Reduction of hexachloroethane and carbon tetrachloride at surfaces of biotite, vermiculite, pyrite, marcasite. In Organic substances and sediments in water, volume 2. Lewis Publishers, Inc. 349-364. 

Mixed-layer illite-montmorillonite is by far the most abundant (in the vicinity 90%) mixed-layer clay. The two layers occur in all possible proportions from 9 1 to 1 9. Many of those with a 9 1 or even 8 2 ratio are called illites or glauconites (according to Hower, 1961, all glauconites have some interlayered montmorillonite) and those which have ratios of 1 9 and 2 8 are usually called montmorillonite. This practice is not desirable and js definitely misleading. Other random mixed-layer clays are chlorite-montmorillonite, biotite-vermiculite, chlorite-vermiculite, illite-chlorite-montmorillonite, talc-saponite, and serpentine-chlorite. Most commonly one of the layers is the expanded type and the other is non-expanded. 

Much of the derived expanded clay, even that which resembles montmorillonite (holds two layers of ethylene glycol), will contract to 10 A when exposed to a potassium solution. Weaver (1958) has shown that these clays can obtain sufficient potassium from sea water and readily contract to 10 A. Vermiculite and mixed-layer biotite-vermiculites are rare in marine sedimentary rocks. Weaver (1958) was unable to find any expandable clays in marine sediments that would contract to 10 A when treated with potassium. A few continental shales contained expanded clays that would contract to 10A when saturated with potassium. Most vermiculites derived from micas and illites have high enough charge so that when deposited in sea water they extract potassium and eventually revert to micas and illites. Some layers may be weathered to such an extent that they do not have sufficient charge to afford contraction and mixed-layer illite-montmorillonites form. 

Bobrov, B. S., Yu. E. Gorbatyi, I. G. Zhigun, and M. B. Epel baum, 1966. Hydromicas in the series biotite-vermiculite and phlogopite-vermiculite. Issled. Prir. Tekh. Mineraloobrazov, Mater. Soveshch., 7th Lvov 1964, 279. 

Regularly interstratified (1 1) chlorite and vermiculite has been attributed to the mineral corrensite [12173-14-7] (141). Chlorite mixed layers have been documented with talc, vermicuhte, smectite, iUite, biotite, kaolinite, serpentine, and muscovite. The mixed-layer mineral is named after the components, eg, talc—chlorite. The eadier Hterature, however, has reference to specific minerals such as kulkeite [77113-95-2] (talc—chlorite and tosudite... 

Silicates with layer. structures include some of the most familiar and important minerals known to man, partieularly the clay minerals [such as kaolinite (china clay), montmorillonite (bentonite, fuller s earth), and vermiculite], the micas (e.g. muscovite, phlogopite, and biotite), and others such as chrysotile (white asbestos). 

Hexachloroethane is also relatively resistant to degradation in the aquatic environment. No hydrolysis of hexachloroethane in water was observed after 11 days at 85 C at 3 pH levels (3, 7, and 11) (Ellington et al. 1987). However, hexachloroethane may be reduced in aquatic systems in the presence of sulfide and ferrous ions (Kriegman-King and Reinhard 1991). The transformation rate of hexachloroethane to tetrachloroethylene under simulated groundwater conditions at 50 C was evaluated without ferrous or sulfide ions, with minerals (biotite and vermiculite) providing ferrous ions, and with minerals and sulfide ions. Reported half-lives for hexachloroethane were 365 days for hexachloroethane alone, 57-190 days with minerals present, and 0.45-0.65 days in the presence of both minerals and sulfide. 

Carbon tetrachloride slowly reacts with hydrogen sulfide in aqueous solution yielding carbon dioxide via the intermediate carbon disulfide. However, in the presence of two micaceous minerals (biotite and vermiculite) and amorphous silica, the rate transformation increases. At 25 °C and a hydrogen sulfide concentration of 0.001 M, the half-lives of carbon tetrachloride were calculated to be 2,600, 160, and 50 d for the silica, vermiculite, and biotite studies, respectively. In all three studies, the major transformation pathway is the formation of carbon disulfide. This compound is... 

Kriegman-King, M.R. and Reinhard, M. Transformation of carbon tetrachloride in the presence of sulfide, biotite. and vermiculite. Environ. Sci. TechnoL, 26(ll) 2198-2206, 1992. 

MgOn(OH)j -] units (Fig. 7.5), and the illite type in which the octahedral sheet is sandwiched between two layers of tetrahedra (cf. micas such as muscovite, Fig. 7.4). Many important clay minerals such as vermiculite, biotite, and smectites (notably montmorillonite and beidellite, the princi-... 

BOETTCHER (A.L.), 1966. Vermiculite, hydrobiotite and biotite in the Rainy Creek igneous complex near Libby, Montana. Clay Min., 6, ... 

Trioctahedral illites have been reported by Walker (1950) and Weiss et al.(1956). Walker s analysis, which he considers only a rough approximation, is given in Table XI. The clay biotite occurs in a Scottish soil and is believed to be authigenic however, it weathers so easily to vermiculite that unweathered material is difficult to find. Due to its instability, it is not likely that much clay-sized biotite exists although trioctahedral biotite-like layers may occur interlayered with dioctahedral illite layers. Such interlayering has been reported by Bassett (1959). 

Most of the vermiculites listed by Foster apparently were formed by the leaching of K from biotite. Biotite has a negative layer charge near 1.00 per Oi0(OH)2 units. Foster s vermiculites have charges from 1.08 to 0.38 with only five of 25 values... 

High-iron biotites are not likely to alter to vermiculite. When the ferrous iron content is sufficiently high, oxidation will result in a positive layer charge and the extension of the octahedral sheet to such an extent that the basic layer would be unstable and break up quite rapidly. 

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. 

Barshad, I. 1954. Cation exchange in micaceous minerals. II. Replaceability of ammonium and potassium from vermiculite, biotite, and montmorillonite. Soil Sci. 78 57-76. 

Figure 4 Age of moraines in the Wind River Mountains, Wyoming, on which soils of a chronosequence have formed (with the names of the glacial advances labeled) versus the Sr/ Sr of the B-horizon soil exchangeable fraction (circles) and C-horizon total soil digests (open squares). Also plotted are analyses of mineral separates from the granitoid bedrock in the area (filled symbols). The elevated Sr/ Sr in the younger soils was attributed to the release of radiogenic Sr as biotite is altered to form hydrobiotite and vermiculite (source Blum and Erel, 1997).

Forster (1961, 1963) reported a similar release and uptake of K by the mycelium of A. niger and a variety of other soil fungi when incubated with orthoclase and oligoclase. Weed et al. (1969) demonstrated that fungi weathered biotite, muscovite and phlogopite to vermiculite by acting as a sink for the K released from these minerals. Wheat plants apparently function in this manner during the alteration of biotite to vermiculite (Mortland etal., 1956). 

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