Hydrated magnesium-iron-aluminum silicate

Synonyms Hydrated magnesium aluminum iron silicate Definition Hydrated magnesium-iron-aluminum silicate a specific form of mica that exfoliates under heat into thin, lightweight flakes Properties Lt. brown platelet-type cryst. structure sol. in hot cone, sulfuric acid insol. in water and org. soivs. sp.gr. 2.25 bulking value 0.053 gal/lb... 

Tliese clays are hydrated magnesium aluminum silicates containing some iron and calcium. 

Bentonite is a native colloidal hydrated aluminum silicate consisting mainly of montmorillonite, Al203-4Si02-H20 it may also contain calcium, magnesium, and iron. The average chemical analysis is expressed as oxides, see Table I, in comparison with magnesium aluminum silicate. 

The PhEur 2005 describes bentonite as a natural clay containing a high proportion of montmorillonite, a native hydrated aluminum silicate in which some aluminum and silicon atoms may be replaced by other atoms such as magnesium and iron. 

Talc is a purified, hydrated, magnesium silicate, approximating to the formula Mgg(Si205)4(0H)4. It may contain small, variable amounts of aluminum silicate and iron. 

Bentonite, Wilkinite. A colloidal native hydrated aluminum silicate (clay) found in the midwest of the U.S A. and in Canada. Consists principally of montmori]Ionite. Alj034Si0,.Ha0. Usually contains some magnesium, iron, and calcium carbonate. Review J. Alexander Ind. Eng. Chem. 16, 1140 (1924). 

Inorganic colorants listed in 21CFR 178.3297 include aluminum, aluminum hydrate, potassium silicate, aluminum silicate, barium sulfate, bentonite, calcium carbonate, calcium silicate, calcium sulfate, carbon black (channel process, prepared by the impingement process from stripped natural gas), chromium oxide green Cr203, cobalt aluminate (with restrictions), diatomaceous earth, iron oxides, kaolin (modified for use in olefin polymers in amounts up to 40%), magnesium oxides, magnesium silicate (talc), sienna, silica, titanium dioxide, titanium dioxide-barium sulfate, ultramarines, zinc carbonate (limited use), zinc chromate (less than 10%), zinc oxide (limited use), and zinc sulfide (less than 10%). 

Hydrated alumina Hydrated aluminum oxide. See Aluminum hydroxide Hydrated aluminum silicate. See Pyrophyllite Kaolin Hydrated ferric oxide. See Iron oxide yellow monohydrate Hydrated magnesium aluminum iron silicate. See Vermiculite Hydrated silica. See Silica, hydrated... 

Hydrated magnesium aluminum iron silicate. See Vermiculite... 

Lithium hydroxide absorbent, carbon monoxide Copper chloride (ous) absorbent, chemical processes Iron (III) oxide hydrated absorbent, chemical specialties Magnesium aluminum silicate absorbent, CO2... 

Vermiculite is a naturally occurring group of hydrated aluminum-iron-magnesium silicates having a laminate structure. When subjected to direct heat in a furnace, the pulverized material exfoliates or expands in size, and then consists of a series of parallel plates with air spaces between. 

Vermiculite Concentrate (also raw or unexfoliated vermiculite)—The mineralogical name given to hydrated laminar magnesium-aluminum-iron silicate (Mg,Ca,K,Fe(II)3(Si,Al,Fe(III)40io(OH)204H20) minerals, which resemble mica in appearance. This mineral has the unusual property of exfoliating or expanding to a low density, bulky material when heated (see Vermiculite). 

Asbestos is a fibrous mineral mined from rock deposits. There are approximately 30 types of minerals in the asbestos group. Of the six that have commercial importance, only oneotile, a hydrated silicate of magnesium that contains small amounts of iron and aluminum, oxides, is used in fiber processing. 

Clays are layered, hydrated silicates of aluminum, iron, and magnesium.225 Most are crystalline inorganic polymers, but a few are amorphous. They consist of tetrahedral and octahedral layers as shown in Fig. 6.2. 

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