Fibrous clay minerals

Fibrous zeolites (natrolite, scolecite, thomsonite, edingtonite) Fibrous clay minerals (attapulgite sepiolite)... 

The mineralogy that comprises the clay component of the soil is also critical to contamination of soils by biological and chemical threat agents. For example, ricin was sorbed to four different clay minerals as described above (Figure 4.2). Kaolinite, a 1 1 clay mineral, sorbed very little ricin. Sepiolite, a fibrous clay mineral, sorbed much more ricin. Illite, a tetrahedrally substituted 2 1 clay mineral, sorbed similar amounts of ricin as the sepiolite. The octahedrally substituted clay mineral, montmorillonite, sorbed much greater quantities than all of the other clay minerals. Even with this clay mineral, the cation that was dominantly sorbed to the clay made a difference. The Na-saturated montmorillonite sorbed more than the Ca-saturated montmorillonite. This is thought to be due to the swelling of the interlayers of the clays. Na-saturated clays swell more so than do Ca-saturated ones. Similar results are shown with aflatoxin Bj (Jaynes et al. 2007). 

Ruiz-Hitzky E, Aranda P, Darder M, Fernandes FM (2013) Fibrous clay mineral-polymer nanocomposites. In Bergaya F, Lagaly G (eds) Handbook of clay science. Part A fundamentals, 2nd edn. Elsevier, Amsterdam, pp 721-741... 

Silicate minerals that usually occur as spherulitic aggregates of fibers have formed as a result of the alteration of the many minerals subsumed within the category of biopyriboles. Alteration of the micas under hydrothermal conditions produces compositional variants on recrystallization such as hydrous muscovite. Some of these samples have been labeled asbestiform, probably because they are found in veins that criss-cross rock masses. Fibrous micaceous minerals also occur as discrete disseminated particles, although few detailed analyses of crystallites from the disperse occurrences have been made. Fibrous mica found in veins usually grades (composition-ally) into members of the serpentine mineral group, the clays or the chlorites. 

Clays are silicate minerals that may be platy or fibrous and are usually of exceedingly fine grain size, ranging from colloidal, a few nanometers in diameter, to a maximum of about a tenth of a micrometer. Similarly to other aluminosilicates, clays show considerable range in chemical composition with concomitant structural modifications (Fig. 2.13). A few of the clay minerals described as fibrous are briefly mentioned here. 

One of the four compositional groups of clay minerals, the kandites include the minerals kaolinite, dickite, halloysite, and metahalloysite all have virtually the same composition. The first two minerals are common and widely used in the production of ceramics the latter two occur in tubular fibrous form. 

DcSousa Santos, P., Brindley, G.W. and De Sousa Santos, H., 1965. Mineralogical studies of kaolinite-halloysite clays, 3. A fibrous kaolin mineral from Piedade, Sao Paulo, BrasiL Am Mineralogist, 50 619—628. 

Hydrotalcite (HT) is a clay mineral which on crushing becomes a fine powder, similar to talc. It is a hy-droxycarbonate of Mg and A1, of the general formula Mg6Al2(0H)i6C03 - 4H20, and occurs in nature in foliated and controlled plates and/or fibrous masses. Anionic clays of the HT type have been of importance in catalysis since 1970. Their interesting properties for catalytic applications are ... 

Isomorphic substitution is especially significant in the case of clay minerals (hydrous aluminum silicates), which are formed by the weathering of the primary silicates of igneous rocks. Most of the clay minerals belong to the phyllosilicates, but there are some that are of fibrous and amorphous structure. 

Authigenic clay minerals identified by SEM/EDS include minor amounts of kaolinite, chlorite, illite and mixed-layer illite/smectite, which form grain coatings, platelets or fibrous cements. 

Palygorskite and sepiolite Authigenic clay minerals (<2pm particle size) in the deep-sea include the fibrous minerals palygorskite and sepiolite and the smectite family of expandable phyllosilicates. Both palygorskite and sepiolite are rare in recent marine... 

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