Silicate

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In chemistry, a silicate is a compound consisting of silicon and oxygen (Si_xO_y), one or more metals, and possibly hydrogen. It is also used to denote the salts of silica or of one of the silicic acids.

In common conditions, the most stable form is silicon dioxide, SiO₂, often called quartz, and similar species. This always has, in equilibrium, a minute amount of silicic acid, H₄SiO₄. Chemists consider quartz as insoluble, but it moves around at longer timescales. Also, in basic conditions, we find H₂SiO₄²⁻.Most silicates are insoluble.

Silicate minerals are noted for their tetrahedral form. Sometimes the tetrahedra are joined in chains, double chains, sheets, and three-dimensional frameworks. They are subclassified into groups based on the degree of polymerization of the tetrahedra, such as nesosilicates, cyclosilicates, and so forth.

In geology and astronomy, the term silicate is used to denote a type of rock that consists of silicon and oxygen (usually as SiO₂ or SiO₄), one or more metals, and possibly hydrogen. Such rocks range from granite to gabbro. Most of the Earth's crust is made up of silicate rocks, as are the crusts of other terrestrial planets.

Mineralogically, silicate minerals are divided according to their molecular structure into the following groups:

• Olivine (single tetrahedron) - Nesosilicates
• Epidote (double tetrahedra) - Sorosilicates
• Tourmaline (rings of tetrahedra) - Cyclosilicates
• Pyroxene (single chain) - Inosilicates
• Amphibole (double chain) - Inosilicates
• Micas and clays (sheet) - Phyllosilicates
• Feldspars (framework) - Tectosilicates
• Quartz (SiO₂ framework)

See also

• Sand
• Silicate dihydroxide

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Silicates are also the number one producer of diatoms in water.

als:Silikat ca:Silicat de:Silikate et:Silikaadid es:Silicato fr:Silicate nl:Silicaat pl:Krzemiany pt:Silicato ru:Силикат sr:Силикати fi:Silikaatti (yhdiste)