Aluminium silicate (or aluminum silicate) is a name commonly applied to chemical compounds which are derived from aluminium oxide, Al₂O₃ and

silicon dioxide Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one ...

, SiO₂ which may be

anhydrous A substance is anhydrous if it contains no water. Many processes in chemistry can be impeded by the presence of water; therefore, it is important that water-free reagents and techniques are used. In practice, however, it is very difficult to achi ...

or hydrated, naturally occurring as

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2 ...

s or synthetic. Their chemical formulae are often expressed as xAl₂O₃·ySiO₂·zH₂O. It is known as

E number E numbers ("E" stands for "Europe") are codes for substances used as food additives, including those found naturally in many foods such as vitamin C, for use within the European Union (EU) and European Free Trade Association (EFTA). Commonly ...

E559.

Examples

* Al₂SiO₅, (Al₂O₃·SiO₂), which occurs naturally as the minerals

andalusite Andalusite is an aluminium nesosilicate mineral with the chemical formula Al2SiO5. This mineral was called andalousite by Delamétehrie, who thought it came from Andalusia, Spain. It soon became clear that it was a locality error, and that the spe ...

kyanite Kyanite is a typically blue aluminosilicate mineral, found in aluminium-rich metamorphic pegmatites and sedimentary rock. It is the high pressure polymorph of andalusite and sillimanite, and the presence of kyanite in metamorphic rocks gener ...

and

sillimanite Sillimanite is an aluminosilicate mineral with the chemical formula Al2SiO5. Sillimanite is named after the American chemist Benjamin Silliman (1779–1864). It was first described in 1824 for an occurrence in Chester, Connecticut. Occurrence ...

which have different crystal structures. * Al₂Si₂O₅(OH)₄, (Al₂O₃·2SiO₂·2H₂O), which occurs naturally as the mineral

kaolinite Kaolinite ( ) is a clay mineral, with the chemical composition Al2 Si2 O5( OH)4. It is an important industrial mineral. It is a layered silicate mineral, with one tetrahedral sheet of silica () linked through oxygen atoms to one octahed ...

and is also called aluminium silicate dihydrate.Handbook of Inorganic Compounds, Dale L. Perry, Taylor & Francis, 2011, It is a fine white powder and is used as a filler in paper and rubber and also used in paints. * Al₂Si₂O₇, (Al₂O₃·2SiO₂), called metakaolinite, formed from kaolin by heating at . * Al₆Si₂O₁₃, (3Al₂O₃·2SiO₂), the mineral

mullite Mullite or porcelainite is a rare silicate mineral formed during contact metamorphism of clay minerals. It can form two stoichiometric forms: 3 Al2 O32 SiO2 or 2Al2O3 SiO2. Unusually, mullite has no charge-balancing cations present. As a result, th ...

, the only thermodynamically stable intermediate phase in the Al₂O₃-SiO₂ system at atmospheric pressure.Ceramic and Glass Materials: Structure, Properties and Processing, James F. Shackelford, R. H. Doremus, Springer, 2008, This also called '3:2 mullite' to distinguish it from 2Al₂O₃·SiO₂, Al₄SiO₈ '2:1 mullite'. * 2Al₂O₃·SiO₂, Al₄SiO₈ '2:1 mullite'.

Aluminium silicate composite materials, fibres

Aluminium silicate is a type of fibrous material made of aluminium oxide and silicon dioxide, (such materials are also called aluminosilicate fibres). These are glassy solid solutions rather than chemical compounds. The compositions are often described in terms of % weight of alumina, Al₂O₃ and

silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is ...

, SiO₂. Temperature resistance increases as the % alumina increases. These fibrous materials can be encountered as loose wool, blanket, felt, paper or boards.Concise Encyclopedia of Composite Materials, ed. Anthony Kelly, MIT Press, 1989,

References

External links

Aluminum silicates
at the University of Waterloo, Canada {{Authority control

Silicates In chemistry, a silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula , where . The family includes orthosilicate (), metasilicate (), and pyrosilicate (, ). The name ...

Silicates Orthorhombic minerals E-number additives