Montmorillonite: Difference between revisions
medicinal uses for Montmorillonite - relevant info |
|||
| Line 69: | Line 69: | ||
Similar to many other clays, montmorillonite [[Expansive clay|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. |
Similar to many other clays, montmorillonite [[Expansive clay|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 |
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]]. Montmorillonite is known for its adsorbent qualities and has been used successfully in scientific trials to eliminate [[atrazine]] from water.<ref>http://www3.interscience.wiley.com/cgi-bin/abstract/72503084/ABSTRACT?CRETRY=1&SRETRY=0</ref> |
||
===Calcined clay products=== |
===Calcined clay products=== |
||
Revision as of 23:27, 8 August 2009
| Montmorillonite | |
|---|---|
 A sample of montmorillonite (unknown scale) | |
| General | |
| Category | smectite, phyllosilicate |
| Formula (repeating unit) | (Na,Ca)0.33(Al,Mg)2(Si4O10)(OH)2·nH2O |
| Crystal system | monoclinic 2/m - Prismatic |
| Identification | |
| Color | White, pale pink, bu, yellow, red, green |
| Crystal habit | compact masses of lamellar or globular microcrystalline aggregates |
| Cleavage | [001] perfect |
| Fracture | Uneven |
| Mohs scale hardness | 1-2 |
| Luster | Dull, earthy |
| Diaphaneity | Translucent |
| Specific gravity | 1.7-2 |
| Optical properties | Biaxial (-) 2V: Measured: 5° to 30° |
| Refractive index | nα = 1.485 - 1.535 nβ = 1.504 - 1.550 nγ = 1.505 - 1.550 |
| Birefringence | δ = 0.020 |
| Other characteristics | VIII / H.19-20, cell a = 5.17, b = 8.94, c = 9.95 |
| References | [1][2] |
| Structure | |
|---|---|
| C 2/m | |
a = 5.17, b = 8.94, c = 9.95
| |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
| |
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.
It 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.
Uses
It 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. Montmorillonite is known for its adsorbent qualities and has been used successfully in scientific trials to eliminate atrazine from water.[3]
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.
Discovery
Montmorillonite was discovered in 1847 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.[4] This process may have led to the origin of life on Earth. [5]
See also
References
- ^ http://rruff.geo.arizona.edu/doclib/hom/montmorillonite.pdf Mineral Data Publishing
- ^ http://www.mindat.org/min-2821.html Mindat
- ^ http://www3.interscience.wiley.com/cgi-bin/abstract/72503084/ABSTRACT?CRETRY=1&SRETRY=0
- ^ Clays May Have Aided Formation of Primordial Cells
- ^ Clay's matchmaking could have sparked life
- Papke, Keith G. Montmorillonite, Bentonite and Fuller’s Earth Deposits in Nevada, Nevada Bureau of Mines Bulletin 76, Mackay School of Mines, University of Nevada-Reno, 1970.
- Mineral Galleries
- Mineral web
