Structural Classification of Silicates

The structural classification of silicates is based on the polymerization of silicon tetrahedra (Si04) and on the proportion of silicon-to-oxygen atoms (Si 0) as follows ... 

Structural Classification of Silicates Found in Glass-Ceramics ... 

In order to study in more detail the clay minerals, it is first helpful to review briefly the basic structural classification of the silicates in general. Although ultimately complicated, the general progression is logical, and is based on the degree of polymerization of the basic structural unit which is the Si04 tetrahedron (see below). The sequence runs as follows ... 

The chemical classification of silicates is based on their multiplicity and type of structural arrangement. It partly differs from the classification commonly adopted in mineralogy (table 5.2). 

Liebau, F. (1985). Structural Chemistry of Silicates. Structure, Bonding and Classification. Berlin Springer. 

F. Liebau, Structural Chemistry of Silicates Structure, Bonding, and Classification, Springer-Verlag, Berlin, 1985. 

TABLE 3E. Classification of Silicate Minerals Based on Structural Arrangements in Silicate Crystal Lattices... 

The silicate minerals are, of course, characterized by the presence of the tetrahedral Si04 cluster unit and the crystal chemistry and classification of silicates dominated by the structures built up by the linking together... 

The structural classification of sulphates on the basis of this concept proves that the variability of mixed complexes in sulphates (Raszvetaieva Pushcharovsky, 1989) is comparable with the diversity of the anionic tetrahedron complexes in silicates (Figure 4). 

F Liebau. Structural chemistry of silicates. Stmctures, bonding and classification. Berlin Springer Verlag, 1985. 

Polyhedra in crystal structures (see Section 10.3) can be used as elements of simpler networks formed by common comers, edges or even faces. Many structures can now be classified into island, chain, sheet and framework stmctures (see Figure 4), Very impressive examples are the classification of silicates, of oxides and oxysalts, or of metals and alloys. ... 

Figure 3.3 The structural classification of the silicate minerals. Note that, with the exception of the tektosilicate structure, these are idealized models.

A. Determination of silica in a soluble silicate Discussion. Most of the silicates which come within the classification of soluble silicates are the orthosilicates formed from SiO units in combination with just one or two cations. More highly condensed silicate structures give rise to the insoluble silicates. 

We have already learnt that the building unit of the silicates is the Si04 pyramid. By linking these pyramids in various ways the different kinds of silicate anions are formed. The classification of the silicates is based on these kinds of ions. The silicate anions of clay minerals have a layered structure, the top view of which is again represented in figure 8.5. 

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