Clay Minerals

(redirected from Clay Mineralogy)

Clay Minerals


a group of hydrous silicates comprising the majority of clays and determining their physicochemical, mechanical, and other properties. Clay minerals are predominantly the product of weathering of aluminosilicates and silicates of magmatic and metamorphic rocks at the surface. In the process of weathering the clay minerals undergo sequential transformations of their structure and chemical composition, depending on the changes in the physicochemical conditions in the weathering and sedimentation medium. The particle size of clay minerals in clays rarely exceeds 0.01 mm. According to their crystalline structure, clay minerals belong to the schistous or pseudoschistous silicates. The crystal lattices of typical clay minerals consist of alternating networks of silicon-oxygen tetrahedrons (silicon ions in tetracoordinate configuration) and of hydroxyl octahedrons surrounding atoms of aluminum, iron, or magnesium. In this case, divalent magnesium is present in every octahedron (trioctahedral silicates), whereas trivalent aluminum is present in two out of three octahedrons (dioctahedral silicates).

Clay minerals with two-level structures consist of tetrahedral and octahedral networks, such as the kaolinite group—for example, kaolinite, dickite, nacrite, and halloysite. Clay minerals with three-level structures consist of two outer tetrahedral networks and an inner octahedral network. Members of this category are the hydromica group, for example, hydromuscovite and glauconite (potassium atoms are located in the spaces between layers); the montmorillonite group, for example, Al-montmorillonite and Fe-montmorillonite, or nontronite (water and exchange cations are located in the spaces between layers); and the chlorite group, with alternating three-level layers and spaces between the layers (octahedral networks) in the structure. Clay minerals of more complex structures are also known.

Definite differences in the chemical composition of the clay minerals correspond to the crystallochemical differences in their structure. As a result of this property, the clay minerals differ sharply from one another. Thus, for example, montmorillonitic minerals have very high exchange capacities and adsorption properties, but these properties are weakly developed in kaolinitic materials. The clay minerals belonging to the hydromica group increase greatly in volume upon heating. Structural determinations on clay minerals are performed by infrared spectroscopy and by chemical, X-ray, electron-diffraction, electron-microscope, and thermal methods.


Ginzburg, I. I., and I. A. Rukavishnikova. Mineraly drevnei kory vyvetrivaniia Urala. Moscow, 1951.
Rentgenovskie metody izucheniia i struktura glinistykh mineralov. Moscow, 1965. (Translated from English.)


References in periodicals archive ?
The objectives of this study were: (i) to determine the content, forms, and distribution of K in cultivated soils and adjoining virgin lands in relation to clay mineralogy composition and other properties; (ii) to group the soil series based on availability of their exchangeable K status; and (iii) to investigate the long-term effects of cultivation on the K status of sugar beet-growing calcareous soils.
Accordingly, clay mineralogy can be used as a proxy to characterise the evolution of the local environmental conditions in response to global climatic changes (Frouin et al.
There are not many works dealing with dislocation clay mineralogy at faults disrupting the rock series at the Prague territory.
Jock Churchman from the University of Adelaide provided advice on clay mineralogy. Exchangeable calcium in 1984 was determined by the Chemistry Branch, Biological and Chemical Research Institute, Rydalmere, New South Wales.
Major part of B horizon is strongly acidic Sampling point SP1 (BC) SP2 (BC) SP3 (BC) Clay (%) 25.5 45.4 28.8 Silt (%) 19.2 25.3 31.4 Sand (%) 55.3 29.3 39.8 Clay mineralogy Kaolinite, some smectite in lower B horizon, increasing down through the soil profile with 8% Smectite at SP3 pH 6.1 4.7 4.8 EC (dS/m) 0.17 0.13 0.07 OM (%) 20.5 7.9 4.7 CEC (cmol/kg) 3.2 6.0 51.2 ECEC (cmol/kg) 3.6 4.8 7.7 Exc Ca (cmol/kg) 1.08 0.18 0.13 Exc Mg (cmol/kg) 2.18 4.22 6.82 Exc Na (cmol/kg) 0.13 0.35 0.54 Exc K (cmol/kg) 0.15 0.04 0.09 ESP (%) 4.0 7.3 7.0 Ca: Mg 0.5 0.04 0.02 Parameter Column 2 Soil Classification Red Ferrosol (Isbell 2002) Soil Taxonomy Oxisols (NRCS 1999) Soil profile Soils with B horizon with free iron oxide content >5% Fe in fine earth fraction (<2mm).
Excursion guide (Second Conference on Clay Mineralogy and Petrography, Prague).
Mamedov AI, Wagner LE, Huang C, Norton DL, Levy GJ (2010) Polyacrylamide effects on aggregate and structure stability of soils with different clay mineralogy. Soil Science Society of America Journal 74, 1720-1732.
Clay mineralogy was determined on 26 soil samples (table 27 of Geeves et al.
The XVIIth Conference on Clay Mineralogy and Petrology was organized by the Czech National Clay Group together with Institute of Rock Structure and Mechanics of Academy of Sciences CR and Institute of Geology of Academy of Sciences CR and in cooperation with Faculty of Sciences Charles University and other institutions.
Clay mineralogy was characterised by X-ray diffraction (XRD) on the initial samples for all six soils.
In addition to particle size analysis, other basic properties including soil bulk density, pH, organic carbon, cation exchange capacity, electrical conductivity, and clay mineralogy were determined using standard physical and mineralogical methods (Klute 1986a) and presented in Table 1.
Bayhan E., Hasdigen S.: Clay Mineralogy of the Lower Tertiary Sequence in the Burdur-Isparta Region (SW Turkey): Origin and Provenance