Aluminosilicate mineral

Mineral

A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...

s are minerals composed of aluminium

Aluminium

Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

, silicon

Silicon

Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...

, and oxygen

Oxygen

Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

, plus countercations. They are a major component of kaolin and other clay minerals.

Andalusite

Andalusite

Andalusite is an aluminium nesosilicate mineral with the chemical formula Al2SiO5.The variety chiastolite commonly contains dark inclusions of carbon or clay which form a checker-board pattern when shown in cross-section....

, kyanite

Kyanite

Kyanite, whose name derives from the Greek word kuanos sometimes referred to as "kyanos", meaning deep blue, is a typically blue silicate mineral, commonly found in aluminium-rich metamorphic pegmatites and/or sedimentary rock. Kyanite in metamorphic rocks generally indicates pressures higher than...

, and sillimanite

Sillimanite

Sillimanite is an alumino-silicate mineral with the chemical formula Al2SiO5. Sillimanite is named after the American chemist Benjamin Silliman . It was first described in 1824 for an occurrence in Chester, Middlesex County, Connecticut, USA....

 are naturally occurring aluminosilicate minerals that have the composition Al

Aluminium

Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

₂Si

Silicon

Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...

O

Oxygen

Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

₅. The triple point

Triple point

In thermodynamics, the triple point of a substance is the temperature and pressure at which the three phases of that substance coexist in thermodynamic equilibrium...

 of the three polymorphs

Polymorphism (materials science)

Polymorphism in materials science is the ability of a solid material to exist in more than one form or crystal structure. Polymorphism can potentially be found in any crystalline material including polymers, minerals, and metals, and is related to allotropy, which refers to chemical elements...

 is located at a temperature of 500 °C and a pressure of 0.4 GPa. These three minerals are commonly used as index mineral

Index mineral

An index mineral is used in geology to determine the degree of metamorphism a rock has experienced. Depending on the original composition of and the pressure and temperature experienced by the protolith , chemical reactions between minerals in the solid state produce new minerals...

s in metamorphic rock

Metamorphic rock

Metamorphic rock is the transformation of an existing rock type, the protolith, in a process called metamorphism, which means "change in form". The protolith is subjected to heat and pressure causing profound physical and/or chemical change...

s.

Hydrated aluminosilicate minerals are referred to as zeolite

Zeolite

Zeolites are microporous, aluminosilicate minerals commonly used as commercial adsorbents. The term zeolite was originally coined in 1756 by Swedish mineralogist Axel Fredrik Cronstedt, who observed that upon rapidly heating the material stilbite, it produced large amounts of steam from water that...

s and are porous structures that are naturally occurring materials.

The catalyst silica-alumina

Amorphous silica-alumina

Amorphous silica alumina is a synthetic substance that is used as a catalyst or catalyst support. It can be prepared in a number of ways for example:* Precipitation of hydrous alumina onto amorphous silica hydrogel* Reacting a silica sol with an alumina sol...

 is an amorphous substance which is not an aluminosilicate compound.

See also

• Aluminium silicate
  Aluminium silicate
  Aluminium silicate has the chemical formula 2SiO3. It has a density of 2.8 to 2.9 g/cm³, a vitreous lustre, a refractive index of 1.56, a Mohs hardness of 4.5-7.5 , and can have orthorhombic crystallography...
  
  
• Silicate minerals
  Silicate minerals
  The silicate minerals make up the largest and most important class of rock-forming minerals, constituting approximately 90 percent of the crust of the Earth. They are classified based on the structure of their silicate group...
  
  
• Calcium aluminosilicate
  Calcium aluminosilicate
  Calcium aluminosilicate, an aluminosilicate compound with calcium cations, most typically has formula CaAl2Si2O8.As a food additive, it is sometimes designated "E556"....
  
  
• Sodium aluminosilicate