Montmorillonite is a very soft phyllosilicate group of minerals that form when they precipitate from water solution as microscopic crystals, known as clay. It is named after Montmorillon in France. Montmorillonite, a member of the smectite group, is a 2:1 clay, meaning that it has two tetrahedral sheets of silica sandwiching a central octahedral sheet of alumina. The particles are plate-shaped with an average diameter around 1 μm and a thickness of 0.96 nm; magnification of about 25,000 times, using an electron microscope, is required to resolve individual clay particles. Members of this group include saponite, nontronite, beidellite, and hectorite.
Montmorillonite is a subclass of smectite, a 2:1 phyllosilicate mineral characterized as having greater than 50% octahedral charge; its cation exchange capacity is due to isomorphous substitution of Mg for Al in the central alumina plane. The substitution of lower valence cations in such instances leaves the nearby oxygen atoms with a net negative charge that can attract cations. In contrast, beidellite is smectite with greater than 50% tetrahedral charge originating from isomorphous substitution of Al for Si in the silica sheet.
The individual crystals of montmorillonite clay are not tightly bound hence water can intervene, causing the clay to swell, hence montmorillonite is a characteristic component of swelling soil. 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, and the exact ratio of cations varies with source. It often occurs intermixed with chlorite, muscovite, illite, cookeite, and kaolinite.
^"Mineralienatlas – Fossilienatlas". mineralienatlas.de. Archived from the original on 23 April 2018. Retrieved 23 April 2018.
^Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C., eds. (1995). "Montmorillonite" (PDF). Handbook of Mineralogy. Vol. II (Silica, Silicates). Chantilly, VA, USA: Mineralogical Society of America. ISBN 0962209716. OCLC 895497384. Archived (PDF) from the original on 2012-02-05. Retrieved 2017-06-22.
^Montmorillonite Archived 2012-05-24 at the Wayback Machine. Mindat.org
^Montmorillonite Archived 2011-06-07 at the Wayback Machine. Webmineral
Montmorillonite is a very soft phyllosilicate group of minerals that form when they precipitate from water solution as microscopic crystals, known as...
consisting mostly of montmorillonite (a type of smectite) which can either be Na-montmorillonite or Ca-montmorillonite. Na-montmorillonite has a considerably...
be found at marine environments. A study in the 1990s showed that montmorillonite clay can help create RNA chains of as many as 50 nucleotides joined...
warm water. In the field of geology, it is more commonly known as montmorillonite. Diosmectite is a contraction of "dioctahedral smectite". Its effectiveness...
between two tetrahedral sheets, and examples are talc, vermiculite, and montmorillonite. The layers in 1:1 clays are uncharged and are bonded by hydrogen bonds...
of montmorillonite, but can often contain secondary minerals such as quartz and calcite. In clay mineralogy, smectite is synonym of montmorillonite (also...
investigate the use of the mineral montmorillonite as a surface for ribonucleotide polymerization and other processes. Montmorillonite is formed by the accumulation...
ion-exchange resins (functionalized porous or gel polymer), zeolites, montmorillonite, clay, and soil humus. Ion exchangers are either cation exchangers...
lakes and marine basins. The main groups of clays include kaolinite, montmorillonite-smectite, and illite. Chlorite, vermiculite, talc, and pyrophyllite...
the quartz based bodies. Dunting also occurs in wares produced from montmorillonite clay bodies due to the volume expansion of cristobalite during its...
"Formation d'une phyllite du type kaolinique par traitement d'une montmorillonite". Comptes Rendus de l'Académie des Sciences de Paris. 224 (1): 53–55...
halloysite (from the proper name), saponite (soapstone),: 187 bentonite or montmorillonite (from the French: Montmorillon, toponym). The last mineral is a large...
other mudrocks. The clay minerals represented are largely kaolinite, montmorillonite and illite. Clay minerals of Late Tertiary mudstones are expandable...
commonly used are kaolin and the smectite clays such as bentonite, montmorillonite, and Fuller's earth. However, their use is declining, and modern evidence-based...
astronomical observatory in Arizona, USA MMt, one million metric tons Montmorillonite, a clay Magical Mystery Tour, a record by the English rock band the...
benzene to cyclohexane catalyzed by rhodium(I) complex supported on montmorillonite clay". Reaction Kinetics and Catalysis Letters. 48 (2): 547. Bibcode:1992RKCL...
within the liposomes than they would have outside. Some clays, notably montmorillonite, have properties that make them plausible accelerators for the emergence...
can be produced non-biologically in the wild. Some clays, notably montmorillonite, have properties that make them plausible accelerators for the emergence...
aluminium phyllosilicate generally impure clay consisting mostly of montmorillonite. There are a few types of bentonites and their names depend on the...
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