Platy minerals clays

De Sousa Santos, P., De Sousa Santos, H. and Brindley, G.W., 1966. Mineralogical studies of kaolinite-halloysite clays, 4. A platy mineral with structural swelling and shrinking characteristics. Am. Mineralogist, 51 1640-1648. 

Platy minerals such as clays and talcs, are useful for providing stiffness to hot, semi-processed rubber products. This is particularly useful for thin-walled extrusions, which emerge from the die at high temperatures. The stiffening effect is usually sufficient to prevent collapse under the product s own weight immediately prior to and during cure. 

Kaolinite. Kaolinite is a leaf-like or platy mineral and is the major constituent of kaolin or china clay. Kaolin is used in the manufacture of paper products, plastics, rubber, ceramics, and refractory materials, and as a filler in paints. It is also found in inks, adhesives, insecticides, medicines, food additives, bleach, absorbents, cements, fertilizers, cosmetics, crayons, pencils, detergents, paste, floor tiles, and textiles. 

J) The extreme fineness of iadividual clay particles, which may be of colloidal size ia at least one dimension. Clay minerals are usually platy ia shape, and less often lathlike and tubular or scroU shaped (13). Because of this fineness clays exhibit the surface chemical properties of coUoids (qv) (14). Some clays possess relatively open crystal lattices and show internal surface colloidal effects. Other minerals and rock particles, which are not hydrous aluminosihcates but which also show colloidal dimensions and characteristics, may occur intimately intermixed with the clay minerals and play an essential role. 

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. 

These clays have distinctive uses and properties not shown by platy clay minerals... 

Clay (mineral) A group of fine-grained and platy aluminum silicate minerals. Kaolinite (ALSiiOs/OH ), montmorillonite ((Al,Mg)g(Si40io)4(OH)8-12H20), and halloysite (Al2Si205(0H)4-2H20) are common clay minerals. 

Fissile The tendency of a sedimentary rock (especially shales) to break into platy fragments. Fissility is usually due to the alignment of platy clay minerals in the rock. 

Clay minerals are hydrous layer silicates of colloidal dimensions, with most if not all of the individual platy particles in the colloidal range of c. 1 nm-1 pm (van Olphen, 1976 Van Damme et al., 1985). The term phyllosilicate (phyllo = leaf like) is applied to the broad group of hydrous silicates with layer structures. The essentia] components of the phyllosilicate structure are two-dimensional tetrahedra and octahedra of oxygen atoms (or ions). The coordinating atoms (or cations) in the centre of the tetrahedra are for the most part Si, but Al3 or Fe3+ may also be present. The coordinating cations in the octahedra are usually Al3, Mg2+, Fe3 or Fe2. Some clay structures (e.g. hectorite) can be synthesized in a reproducible and relatively homogeneous form. 

Clay minerals are frequently platy and a high degree of preferred orientation is required when preparing sample mounts for XRD analysis. This is related to their layer lattice characteristics and atomic sequence normal to the surface of the clay plate. There are numerous ways of preparing orientated mounts, and these include precipitation onto glass slides (Brown, 1953), suction onto unglazed ceramic tiles (Gibbs, 1965 Rich, 1975 Rhoton et al., 1993) and suction onto membrane filters (McAlister and... 

The term clay refers to fine-grained aluminosilicates that have a platy habit and become plastic when mixed with water [11], Dozens of minerals fall under the classification of clays and a single clay deposit can contain a variety of individual clay minerals along with impurities. Clay minerals are classified as phyllosilicates because of their layered structure [12], The most common clay mineral is kaolinite, although others such as talc, montmorillonite, and vermiculite are also abundant. Each of the... 

All cl minerals belong to the phyllosilicate subclass, having thin layers composed of successive tetrahedral and octahedral sheets of atoms and ions. The layers are weakly bonded to one another and thus easily separable to very thin flakes. The platy or flaky nature of the clay particles, thus having large smface areas relative to grain-size, is very much suitable to be used as fillers. 

Talc is a hydrated magnesium silicate, which has a platy shape, similar to clays. Unlike clays, the mineral does not possess a significant level of surface hydroxyl groups, which is the primary reason for the application differences between the two minerals. Talcs have a surface that interacts poorly with rubber (it has a characteristic slippery feel), is basic in character, and is relatively hydrophobic. Good sources of talc are relatively scarce. This has ensured that the cost of talc is relatively high. 

Fig. 5.62 Optical micrographs show the size and shape of several minerals used as fillers for composites (A) mica flakes appear platy in shape with irregular boundaries, (B) talc particles have a much finer, platy texture and the particles exhibit a range of shapes from nearly fibrous to platy and (C) clay particles are very fine grained with no characteristic shape.

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