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Aluminium silicate

This article is about neutral chemical compounds composed solely of aluminium, silicon, and oxygen. For related charged compounds containing counterions, see Aluminosilicate.

Aluminium silicate

Identifiers
CAS Number	12141-46-7 Y
3D model (JSmol)	Interactive image
ChemSpider	8488719 N
ECHA InfoCard	100.032.036
E number	E559 (acidity regulators, ...)
PubChem CID	10313254
UNII	T1FAD4SS2M Y
CompTox Dashboard (EPA)	DTXSID2050451
InChI InChI=1S/2Al.O3Si.2O/c;;1-4(2)3;;/q2*+1;-2;; N Key: PZZYQPZGQPZBDN-UHFFFAOYSA-N N
SMILES O=[Al]O[Si](=O)O[Al]=O
Properties
Chemical formula	Al 2SiO 5
Molar mass	162.0456 g mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Aluminum silicate (oraluminium silicate) is a name commonly applied to chemical compounds which are derived from aluminium oxide, Al₂O₃ and silicon dioxide, SiO₂ which may be anhydrous or hydrated, naturally occurring as minerals or synthetic. Their chemical formulae are often expressed as xAl₂O₃·ySiO₂·zH₂O. It is known as E number E559.

Andalusite, kyanite, and sillimanite are the principal aluminium silicate minerals.^[2][3][4] The triple point of the three polymorphs is located at a temperature of 500 °C (932 °F) and a pressure of 0.4 GPa (58,000 psi). These three minerals are commonly used as index mineralsinmetamorphic rocks.

• Al₂SiO₅, (Al₂O₃·SiO₂), which occurs naturally as the minerals andalusite, kyanite and sillimanite which have distinct crystal structures.
• Al₂Si₂O₇, (Al₂O₃·2SiO₂), called metakaolinite, formed from kaolin by heating at 450 °C (842 °F).^[5]
• Al₆Si₂O₁₃, (3Al₂O₃·2SiO₂), the mineral mullite, the only thermodynamically stable intermediate phase in the Al₂O₃-SiO₂ system at atmospheric pressure.^[6] This also called '3:2 mullite' to distinguish it from 2Al₂O₃·SiO₂, Al₄SiO₈ '2:1 mullite'.
• 2Al₂O₃·SiO₂, Al₄SiO₈ '2:1 mullite'.^[6]

The above list mentions ternary materials (Si-Al-O). Kaolinite is a quaternary material (Si-Al-O-H). Also called aluminium silicate dihydrate, kaolinite occurs naturally as a mineral. Its formula is Al₂Si₂O₅(OH)₄, (Al₂O₃·2SiO₂·2H₂O).^[5]

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, SiO₂. Temperature resistance increases as the % alumina increases. These fibrous materials can be encountered as loose wool, blanket, felt, paper or boards.^[7]

• Aluminum silicates at the University of Waterloo, Canada