Crystal Chemistry of Silicates

Layered aluminosilicates are the most important secondary minerals in the clay fraction of soils. When layer silicate minerals are clay or colloidal size ( 2 gm effective diameter), their large surface area greatly influences soil properties. Most of the important clay minerals have similar silicate structures. Inasmuch as clay minerals are such important clay components, and as different clay minerals can change sail properties greatly, an understanding of soil properties begins with an understanding of silicate structures. 

WTien atoms combine, the bond between them changes the electron distribution from that of the atomic state. The type of bond depends on the electronic structure of the combining atoms. Ionic or electrostatic bonding occurs between oppositely charged ions such as Na+ and Cl-. Such ions are formed by the complete loss or gain of electrons to form positive or negative ions having an electron structure like an inert gas. The formation of Na+ and Cl- from Na and Cl atoms is, for example, 

Ionic bonding is strong, and ionic-bonded compounds tend to be hard solids and have high melting points. Ionic bonding is also undirected—exerted uniformly in all 

Covalent bonding (shared electron pairs) is common between identical atoms or atoms having similar electrical properties, such as in H2O, F2, CH4, and C (diamond). In covalent bonding the electrons are shared between atoms so that each atom attains the inert gas electronic structure. For example, 

Covalent bonding is strong, but directional. Bond angles in covalently bonded structures are determined by the geometric positions of the electron orbitals (orbits) involved. Covalently bonded molecules have little tendency to ionize. Bonding within ionic radicals, or complex ions, such as SO2-, is frequently covalent. 

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Cameron M. and Papike 1 1 (1982). Crystal chemistry of silicate pyroxenes. In Reviews in Mineralogy, vol. 7, 2d ed., P. H. Ribbe (series ed.), Mineralogical Society of America. 

Novak G. A. and Gibbs G. V. (1971). The crystal chemistry of silicate garnets. Amer. Mineral, 56 791-825. 

Papike, J., and M. E. Cameron (1976). Crystal chemistry of silicate minerals of geophysical interest. Rev. Geophys. Space Phys. 14 37-80. 

A. N. Lazarev and A. A. Levin, Quantum Chemistry of Molecular Systems and Crystal Chemistry of Silicates, Nauka, Leningradskoe Otd., Leningrad, 1988. 

The characterization of the structure of these compovinds is of considerable interest for the crystal chemistry of silicates. In most of the silicate structures the silicon-oxygen anion is joined to cations by sufficiently strong bonds. Because of this the size of cation plays the decisive role in the determination of the structure type due to the great capability of the configuration of the silicon-oxygen anion to adapt itself to cationic polyhedra. These... 

Structure of silicates see E. Gorlich Silicate Chemistry , Geological Ed. Warsaw 1957 (in Polish), M. Handke Crystal Chemistry of Silicates , Krakdw 2005, (in Polish). 

For a long time the stmctures of silicates were described as frameworks of close-packed anions, with smaller cations occupying the gaps. In 1959 Belov [292] opened a new era of crystal chemistry of silicates by proving that the basic motif of the... 

Felsche J (1973) The Crystal Chemistry of the Rare-Earth Silicates. 13 99-197 Ferreira R (1976) Paradoxial Violations of Koopmans Theorem, with Special Reference to the 3d Transition Elements and the Lanthanides. 31 1-21 Fichtinger-Schepman AMJ, see Reedijk J (1987) 67 53-89... 

Felsche, J. The Crystal Chemistry of the Rare-Earth Silicates. Vol. 13, pp. 99-197. 

It is well known that, as previously mentioned, close structural relationships exist between phosphates and silicates, as the crystal chemistry of both families is based upon similar X04 tetrahedral networks. The introduction of nitrogen within the P04 tetrahedra further increases the similarities when the cross-substitution is considered ... 

Chapman, D.M., and Roe, A.L. (1990) Synthesis, characterization and crystal chemistry of microporous titanium-silicate materials. Zeolites, 10, 730. 

Since silicates and aluminosilicates are by far the predominant rock-forming minerals, the crystal structures of most species have been determined. Liebau (1980) presents an overview of the structures of silicate and aluminosilicate minerals, and one can consult Berry, Mason, and Dietrich (1983, especially pp. 382-389) or other mineralogy texts for an introduction to the subject. The multivolume work of Eitel (1965) provides a general treatment of the crystal chemistry of all types of silicate materials. 

Bates, T. F. (1959). Morphology and crystal chemistry of 1 1 layer lattice silicates. Amer. Min. 44 78-92. 

Belov, N. V., Crystal Chemistry of Large-Cation Silicates, pp. 34-36, Consultants Bureau, N. Y., Academy of Science Press, Moscow, 1961. 

The crystal chemistry of many transition metal compounds, including several minerals, display unusual periodic features which can be elegantly explained by crystal field theory. These features relate to the sizes of cations, distortions of coordination sites and distributions of transition elements within the crystal structures. This chapter discusses interatomic distances in transition metal-bearing minerals, origins and consequences of distortions of cation coordination sites, and factors influencing site occupancies and cation ordering of transition metals in oxide and silicate structures, which include crystal field stabilization energies... 

Chapter 6 describes how crystal field stabilization energies influence the crystal chemistry of minerals containing the transition elements. Site occupancies of the cations in oxide and silicate structures are also discussed. 

Bums, R. G. (1968) Enrichments of transition metal ions in silicate structures. In Symposium on the Origin and Distribution of Elements. Section V. Terrestrial Abundances. (L. H. Ahrens, ed. Pergamon Press, Oxford), pp. 1151-64. Hawthorne, F. C. (1983) The crystal chemistry of the amphiboles. Canad. Mineral., 21, 173-480. 

Huggins, F. E., Virgo, D. Huckenholtz, H. G. (1977) Titanium-containing silicate garnets, n. The crystal chemistry of melanites and schorlomites. Amer. Mineral., 62,646-65. 

Schmetzer, K. (1978) Der Alexandrit-Effekt in Festkorpem. Naturwiss., 65, 592. Schmetzer, K. (1982) Absorption spectroscopy and colour of V3+-bearing natural oxides and silicates - a contribution to die crystal chemistry of vanadium. Neues Jahrb. Mineral. Abh., 144,73-126. 

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