Hectorite origin

Hectorite. Originally known as hector CLAY from its source near Hector, California, USA. It is a hydrous magnesium silicate related to montmorillonite and forming an end-member of the saponite series. 

Clays are aluminosilicates with a two-dimensional or layered structure including the common sheet 2 1 alumino- and magnesium- silicates (montmorillonite, hectorite, micas, vermiculites) (figure 7.4) and 1 1 minerals (kaolinites, chlorites). These materials swell in water and polar solvents, up to the point where there remains no mutual interaction between the clay sheets. After dehydration below 393 K, the clay can be restored in its original state, however dehydration at higher temperatures causes irreversible collapse of the structure in the sense that the clay platelets are electrostatically bonded by dehydrated cations and exhibit no adsorption. 

Hectorite is an aluminum-free mineral of the smectite type. Isomorphous substitution could occur at tetrahedral silicon sites as well as at the octahedral sites originally occupied by lithium and magnesium. Monitoring the x-ray powder diffraction patterns as a frmction of crystallization time, it was found that the hydrothermal crystallization was complete after 12h at 200°C, independent of the alumina content of the reaction mixture. However, NMR spectroscopy proves that some structural change still occurs after this time period. 

High temperature subsurface water leaches out ions and minerals from the rocks in its contact, and turns into a hot aqueous solution known as hydrothermal solution. It rises through cracks and fractures and picks up dissolved minerals and elements on its way, thus altering the original minerals of the rock to form new minerals. Generally the cations of the original minerals are partly leached out by the hydrothermal liquid, and water molecules enter their structures. Consequently cation-deficient hydrous minerals are formed, a sizeable portion of which are clay minerals. Examples include the formation of halloysite deposits by low temperature hydrothermal alteration of volcanic ash of Northland, New Zealand (Harvey and Murray, 1993) and formation of hectorite by hydrothermal alteration of Li -Mg rich basaltic ash (Harvey and Lagaly, 2006). 

The two end members of this group with mainly tetrahedral substitutions are beidellite and saponite, which are di- and trioctahedral smectites, respectively. The corresponding end members with mainly octahedral substitutions are mont-morillonite and hectorite. Another common smectite, nontronite, is an iron-rich mineral. Chemical compositions of various smectite samples are provided in Table 2. Montmorillonite is the most common mineral of this group it is named for its location in Montmorillon, France. Figures 3d and 3e provide SEM views of the textural morphology of two montmorillonites. A common industrial mineral is bentonite, which is actually a montmorillonite of volcanic ash origin that contains a significant amount of impurities, such as cristobalite (a-quartz), that is intimately mixed with the clay. 

The amount by which a roofing tile overlaps the course next but one below it. Laporite. Trade-name for synthetic hectorite (q.v.) (originally made by the Fuller s Earth Union, which became part of the Laporte Group.)... 

Recently, Wilhelm et modified glycerol-plasticized starch films by the addition of various layered compounds as filler, two being of natural origin (kaolinite, a natural mineral clay and hectorite, a cationic exchange mineral clay) and two synthetic (layered double hydroxide, LDH, an anionic exchanger, and brucite having a neutral structure). Glycerol-plasticized starch/layered compounds composite films were prepared from the respective aqueous... 

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