Also found in: Dictionary.
Related to Aluminosilicates: zeolite



aluminum-silicon saltlike compounds, which in nature make up a group of widely distributed minerals. In the crystalline structure, aluminum-like silicon has a coordination number 4—that is, it is in the center of a tetrahedron surrounded by four oxygen atoms. Aluminum can replace silicon structurally as well as chemically. This means that alumina is similar (but not identical) to silica in its chemical nature. Aluminum can enter into the composition of silicates but still have, like magnesium and other typical base metals, a coordination number 6 (octahedron). In this case the corresponding compounds are aluminosilicates—for instance, mineral topaz, pyrophyllite, and others. Sometimes the silicic anhydride (Si04)4- is replaced by (AlO4)5” in the structural anionic complex of a silicate. This gives rise to an additional negative charge which is compensated by addition of cations, usually K, Na, or bivalent Ca and Ba with large ionic radii.

Silica-type minerals are always aluminosilicates, including aluminosilicates of potassium such as orthoclase and microcline (KAlSi3O8), aluminosilicates of sodium such as albite (NaAlSi3O8), aluminosilicates of calcium such as anorthite (CaAl2Si2O8), and others. Possibility of replacement of the NaSi group by CaAl permits the formation of several compounds of the solid solution type with unlimited solubility, called plagioclases. Aluminosilicates also make up nepheline KNa3[AlSiO4] 4, 4 leucite K[AlSi2Oe], the scapolite group, zeolite, and others. Aluminosilicates are also found quite often among the silicates of sheet structure. To this group belong minerals of the mica family such as muscovite KAl2[AlSI3O10](OH)2, the family of brittle micas such as margante CaAl2[Al2Si2O10](OH)2, the family of chlorites such as amezite (Mg, Fe)4Al2[Al2Si2O10](OH)8, and others. Aluminosilicates are seldom found in other chemicostructural types of silicates. Rare examples of these are hornblende (belt structure), augite (chain structure), and cordierite (ring structure). On disintegration on the earth’s surface aluminosilicates form clay minerals or less often hydrated mica bauxites. The term aliumosilikat was introduced into mineralogy by academician V. I. Vernadskii. He

Table 1. Basic properties of the most widely used aluminosilicate refractory products in the USSR
 Semiacid productsFireclay productsHigh alumina-content products
 Class AClass BClass AClass BVGO-62VGU-62VGO-72
1 MN/m2 ≈ 10 kgf/cm2
Lowest fire resistance ( C) ..................1710167017301670180018001800
Highest apparent porosity (%)...............27303030241724
Lowest limit of durability under pressure (meganewtons per square meter)1 ..........101512.512.5256030
Slag resistance ............................moderatemoderategoodgoodgoodexcellentexcellent
Thermal resistance .........................goodmoderategoodgoodgoodmoderategood

first showed the similar role played by Al and Si in geochemical processes and in the composition of natural compounds. This became a foundation for his aluminum acid theory of silicate structure.


Vernadskii, V. I., and S. M. Kurbátov. Zemnye silikaty, aliumosilikaty i ikh analogi, 4th ed. Moscow-Leningrad, 1937.
Povarennykh, A. S. Kristallokhimicheskaia klassifikatsiia mineral’nykh vidov. Kiev, 1966.


Artificial aluminosilicates are produced by synthesis. The most important are artificial aluminosilicates of the natural mineral zeolite type, the so-called molecular sieves and permutites. Methods of synthesis of aluminosilicates are actually imitations of natural geochemical processes, taking place in overheated water solutions under pressure. Molecular sieves are created in autoclaves at 60° −450°C. A solution of sodium aluminate Na[Al(OH)4] and a water suspension of silicic acid nSiO2 x mH20 with some alkali addition are used as raw materials. Obtained from this mixture, aluminosilicate gel is washed and dried at a temperature of about 100°C. Molecular sieves can also be formed through recrystallization of some minerals in concentrated salt solutions. Permutites can be produced by sintering kaolin Al4[Si4O10](OH)8 or feldspar KAlSi3O8 with quartz α-SiO 2 and soda Na2Co3 at 1,000°C and by other methods. Artificial aluminosilicates are used in chemical and other industries. Especially widely used are molecular sieves. They are used for drying, cleaning, and gas separation in chromatographical analysis of gases and liquids. Permutites are mainly used to decrease hardness of water.


References in periodicals archive ?
The active ingredient of Myco AD (Hydrated sodium calcium aluminosilicate, HSCAS) and Vitamin E and selenium were found as better detoxifying agent among the toxin binders used in this study.
Pb sulphide is dispersed in aggregates of aluminosilicates (illite, kaolinite, muscovite and chlorite), and accompanying gypsum crystals (Fig.
Diminution of aflatoxicosis in growing chicken by dietary addition of hydrated sodium calcium aluminosilicates.
Dander was primarily in the 20-100 [micro]m range, and aluminosilicates were in the 5-20 [micro]m range.
Formation of the aluminosilicate zeolite gismondine is also observed.
2] pigment coated with 18% porous aluminosilicate (82% [TiO.
The strong positive interrelationships amongst the various trace elements and major insoluble residues (Figure 10) underline the relevance of the minor aluminosilicate phase in controlling the distribution of both insoluble components and most trace elements.
Most clays and zeolites are hydrated and composed of mainly aluminum and silica and belong to the group of aluminosilicates.
In the last few years, most studies related to the alleviation of mycotoxicosis by the use of adsorbents are focused on aluminosilicates (mainly zeolites, hydrated sodium calcium aluminosilicates (HSCAS), and aluminosilicate-containing clays), and esterified glucomannan (EGM) derived from cell wall of Saccharomyces cerevisiae1026.
Key words: alkali-activated materials, alkaline activation, aluminosilicates, fly-ash
In the context of these known sources, the results for Al, and a cluster of elements associated with aluminosilicates, are unusual.