All silicate minerals contain Si atoms bonded to four O atoms in a tetrahedral arrangement. The simplest involve the orthosilicate ion (SiO 4 4– ).

Each oxygen is bonded to only one Si and has a residual negative charge. Examples of orthosilicate minerals are zircon (ZrSiO 4 ) and forsterite (Mg 2 SiO 4 ).  

When an oxygen atom is shared by two Si atoms, the pyrosilicate anion (Si 2 O 7 6– ) is obtained. 

The Lewis structure shows single bonds, octets on each atom, and a tetrahedral geometry around the Si atom. Some pyrosilicate minerals are akermanite (Ca 2 MgSi 2 O 7 ), lawsonite (CaAl 2 Si 2 O 7 (OH)2 ), and hemimorphite (Zn 4 (OH)2 Si 2 O 7 ). 

The silicate units can continue to link through sharing oxygen atoms to form long single chains of the general formula SiO 3 2–

or long double chains having the formula Si 4 O 11 6– .

Examples of some of SiO 3 2– minerals are enstatite(MgSiO 3 ) and spodumene (LiAl(SiO 3 ) 2 ). Tremolite (Ca 2 Mg 5 Si 8 O 22 (OH)2 ) is an example of a mineral with double chains. SiO x tetrahedra can also link into two-dimensional planar sheets of atoms, where each Si atom shares oxygen atoms with three other silicons. These minerals have the general formula Si 4 O 10 4– and are called sheet silicates. Chrysolite (Mg 6 Si 4 O 10 (OH)8 ) is an example. In micas one Si is replaced by an Al, for example, muscovite (KAl 2 AlSi 3 O 10 (OH)2 ).

A logical extension of this build-up of tetrahedra is to have all four oxygens in a tetrahedral silicate unit shared by Si atoms in adjacent units. The result is quartz, with an empirical formula of SiO 2 . The quartz structure can be imagined by viewing the three-dimensional linked structure of diamond.  SiO 2 would have Si’s where each C is in the diamond structure; the oxygen atoms are then midway between each pair of Si atoms. 

The one-, two-, or three-dimensional links of SiO x units lead to their physical properties. Asbestos is mixed minerals of the long, double-chain type. Thus, they are needle-like, which may account for some of the damage they do to living tissue. Micas are slippery due to two-dimensional sheets of SiO x units that can slide over each other. Quartz has structural strength because of its three-dimensional covalent linking of SiO x units.