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{{Infobox Country
http://wn.com/France -
Vienne () is a département of France, named after the river Vienne.
http://wn.com/Vienne
- aluminosilicate
- bentonite
- calcined
- cave
- Chlorite group
- Clay mineral
- cookeite
- cosmetics
- crystal
- desiccant
- Dispersion (soil)
- drilling mud
- Emulsion dispersion
- endellite
- Expansive clay
- France
- H-M symbol
- halloysite
- illite
- kaolinite
- landfills
- levee
- micelles
- micrometre
- moisture
- Monoclinic
- Montmorillon
- muscovite
- nucleotides
- octahedral
- palygorskite
- playing fields
- RNA
- Sand casting
- saponite
- Silicate mineral
- Silicate minerals
- smectite
- Sodification
- soil
- Space group
- tetrahedral
- Vesicle (biology)
- Vienne
- viscous
- volcanic ash
- water (molecule)
- water wells
- weathering
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- akadama
- aluminosilicate
- bentonite
- calcined
- cave
- Chlorite group
- Clay mineral
- cookeite
- cosmetics
- crystal
- desiccant
- Dispersion (soil)
- drilling mud
- Emulsion dispersion
- endellite
- Expansive clay
- France
- H-M symbol
- halloysite
- illite
- kaolinite
- landfills
- levee
- micelles
- micrometre
- moisture
- Monoclinic
- Montmorillon
- muscovite
- nucleotides
- octahedral
- palygorskite
- playing fields
- RNA
- Sand casting
- saponite
- Silicate mineral
- Silicate minerals
- smectite
- Sodification
- soil
- Space group
- tetrahedral
- Vesicle (biology)
- Vienne
- viscous
- volcanic ash
- water (molecule)
- water wells
- weathering
size: 8.3Kb
name | Montmorillonite |
---|---|
category | smectite, phyllosilicate |
formula | (Na,Ca)0.33(Al,Mg)2(Si4O10)(OH)2·nH2O |
symmetry | Monoclinic prismaticH-M symbol: 2/mSpace group: C2/m |
unit cell | a 5.17 Å, b 8.94 Å, c 9.95 Å; β 99.54°; Z 1 |
color | White, pale pink, blue, yellow, red, green |
habit | compact masses of lamellar or globular microcrystalline aggregates |
system | Monoclinic |
cleavage | [001] perfect |
fracture | Uneven |
mohs | 1-2 |
luster | Dull, earthy |
diaphaneity | Translucent |
gravity | 1.7-2 |
opticalprop | Biaxial (-) |
refractive | nα 1.485 - 1.535 nβ 1.504 - 1.550 nγ 1.505 - 1.550 |
birefringence | δ 0.020 |
2v | Measured: 5° to 30° |
references | }} |
Montmorillonite is a very soft phyllosilicate group of minerals that typically form in microscopic crystals, forming a clay. It is named after Montmorillon in France. Montmorillonite, a member of the smectite family, is a 2:1 clay, meaning that it has 2 tetrahedral sheets sandwiching a central octahedral sheet. The particles are plate-shaped with an average diameter of approximately one micrometre. Members of this group include saponite.
Montmorillonite is the main constituent of the volcanic ash weathering product, bentonite.
The water content of montmorillonite is variable and it increases greatly in volume when it absorbs water. Chemically it is hydrated sodium calcium aluminium magnesium silicate hydroxide (Na,Ca)0.33(Al,Mg)2(Si4O10)(OH)2·nH2O. Potassium, iron, and other cations are common substitutes, the exact ratio of cations varies with source. It often occurs intermixed with chlorite, muscovite, illite, cookeite, and kaolinite.
Cave conditions
Montmorillonite can be concentrated and transformed within cave environments. The natural weathering of the cave can leave behind concentrations of aluminosilicates which were contained within the bedrock. Montmorillonite can form slowly in solutions of aluminosilicates. High HCO3 concentrations and long periods of time can aid in the formation. Montmorillonite can then transform to palygorskite under dry conditions and to endellite in acidic conditions (pH 5 or lower). Endellite can further transform into halloysite by drying.
Uses
Montmorillonite is used in the oil drilling industry as a component of drilling mud, making the mud slurry viscous which helps in keeping the drill bit cool and removing drilled solids. It is also used as a soil additive to hold soil water in drought prone soils, to the construction of earthen dams and levees and to prevent the leakage of fluids. It is also used as a component of foundry sand and as a desiccant to remove moisture from air and gases.Similar to many other clays, montmorillonite swells with the addition of water. However, some montmorillonites expand considerably more than other clays due to water penetrating the interlayer molecular spaces and concomitant adsorption. The amount of expansion is due largely to the type of exchangeable cation contained in the sample. The presence of sodium as the predominant exchangeable cation can result in the clay swelling to several times its original volume. Hence, sodium montmorillonite has come to be used as the major constituent in non-explosive agents for splitting rock in natural stone quarries in order to limit the amount of waste, or for the demolition of concrete structures where the use of explosive charges is unacceptable.
This swelling property makes montmorillonite-containing bentonite useful also as an annular seal or plug for water wells and as a protective liner for landfills. Other uses include as an anti-caking agent in animal feed, in paper making to minimize deposit formation and as a retention and drainage aid component. Montmorillonite has also been used in cosmetics.
Sodium montmorillonite is also used as the base of some cat litter products, due to its adsorbent and clumping properties.
Calcined clay products
Montmorillonite can be (calcined) to produce arcillite, a porous, calcined clay sold as a soil conditioner for playing fields and other soil products such as for use as bonsai soil as an alternative to akadama.
Use in medicine and pharmacology
Montmorillonite clay is widely used in medicine and pharmacology.Montmorillonite is effective as an adsorptive of heavy metals, toxins, and hazardous chemicals.
For external use, montmorillonite has also shown its effectiveness.
Discovery
Montmorillonite was first described in 1847 for an occurrence in Montmorillon in the Vienne prefecture of France, more than 50 years before the discovery of bentonite in the US. It is found in many locations world wide and known by other names.
Lipid organization
Montmorillonite is also known to cause micelles (lipid spheres) to assemble together into vesicles. These are structures that resemble cell membranes on many cells. It can also help nucleotides to assemble into RNA which will end up inside the vesicles and, under the right conditions, will replicate themselves. This process may have led to the origin of life on Earth.
See also
References
Category:Smectite group Category:Magnesium minerals Category:Sodium minerals Category:Calcium minerals Category:Desiccants Category:Geotechnical engineering Category:Medicinal clay Category:Cave geology
ca:Montmorillonita cs:Montmorillonit de:Montmorillonit es:Montmorillonita fa:مونتموریونیت fr:Montmorillonite it:Montmorillonite he:×ž×•× ×˜×ž×•×¨×™×œ×•× ×™×˜ hu:Montmorillonit nl:Montmorilloniet ja:モンモリãƒãƒ³çŸ³ pl:Montmorillonit pt:Montmorillonita ru:Монтмориллонит sk:Montmorillonit sl:Montmorijonit uk:Монтморилоніт vi:MontmorillonitThis text is licensed under the Creative Commons CC-BY-SA License. This text was originally published on Wikipedia and was developed by the Wikipedia community.