Editing Silicate (section)

==Structural principles==
In most silicates, a silicon atom occupies the center of an idealized [[tetrahedron]] whose corners are four oxygen atoms, connected to it by single [[covalent bond]]s according to the [[octet rule]].<ref name=green>{{Greenwood&Earnshaw2nd}}</ref> The oxygen atoms, which bears some negative charge, link to other cations (M<sup>n+</sup>).  This Si-O-M-O-Si linkage is strong and rigid, which properties are manifested in the rock-like silicates.<ref>{{Cite book |title=The 23rd edition of the manual of mineral science. Buch |date=2008 |publisher=Wiley |isbn=978-0-471-72157-4 |location=Hoboken, N.J}}</ref>{{rp|435}}  The silicates can be classified according to the length and crosslinking of the silicate anions.

===Isolated silicates===
Isolated [[orthosilicate]] anions have the formula {{chem|SiO|4|4−}}. A common mineral in this group is [[olivine]] ({{chem2|(Mg,Fe)2SiO4}}).

Two or more silicon atoms can share oxygen atoms in various ways, to form more complex anions, such as [[pyrosilicate]] {{chem|Si|2|O|7|6−}}.

===Chains===
[[File:Silicate-single-chain-plan-view-2D.png|thumb|Depiction of a metasilicate chain, emphasizing the tetrahedral silicate subunits.]]
[[File:Na2SiO3idealized.png|thumb|right|220 px|Alternative depiction of a metasilicate chain emphasizing the Si-O bonds.]]
With two shared oxides bound to each silicon, cyclic or polymeric structures can result.  The cyclic [[metasilicate]] ring {{chem|Si|6|O|18|12−}} is a [[hexamer]] of SiO<sub>3</sub><sup>2-</sup>.  [[Polymer]]ic silicate anions of can exist also as long chains.

In single-chain silicates, which are a type of [[inosilicate]], tetrahedra link to form a chain by sharing two oxygen atoms each. A common mineral in this group is [[pyroxene]].

[[File:Silicate-double-chain-plan-view-2D.png|thumb|alt=Double chain tetrahedra.|Double chain tetrahedra.]]
Double-chain silicates, the other category of inosilicates, occur when tetrahedra form a double chain (not always but mostly) by sharing two or three oxygen atoms each. Common minerals for this group are [[amphiboles]].

=== Sheets ===
[[File:Silicate-sheet-3D-polyhedra.png|thumb|alt=Sheet Silicates.|Sheet silicates.]]
In this group, known as [[phyllosilicates]], tetrahedra all share three oxygen atoms each and in turn link to form two-dimensional sheets. This structure does lead to minerals in this group having one strong cleavage plane. [[Micas]] fall into this group. Both [[muscovite]] and [[biotite]] have very weak layers that can be peeled off in sheets.

=== Framework ===

In a framework silicate, known as a [[tectosilicate]], each tetrahedron shares all 4 oxygen atoms with its neighbours, forming a 3D structure. [[Quartz]] and [[feldspar]]s are in this group.