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Qualitative and quantitative analysis of clay soils
Šašek, Petr ; Viani, Alberto ; Ševčík, Radek ; Fabeš, Roman ; Řehoř, M.
Clay minerals are a group of aluminum silicates with a layered structure, which is formed by tetrahedrally and octahedrally arranged molecules with cations of potassium, magnesium, sodium and others. By combining layers of octahedra and tetrahedra several types of layered structures may be produced, which can form various types of clay minerals in nature. Clay minerals are divided into three main groups: kaolinite, smectite and illite. The aim of the study was to qualitatively and quantitatively analyse the clay minerals in soil samples; the main objective was to determine the phase transition on the boundary of smectite and illite phases. For this purpose XRD analysis with Rietveld refinement was employed.
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Thermal behaviour of organically modified clays
Plevová, Eva ; Vaculíková, Lenka ; Vítámvásová, E. ; Šugárková, Věra ; Martynková, G.S.
The clay minerals were modified by two alkylammonium cations under sorption procedure. T X-ray powder diffraction and FT-IR spectroscopy were used to evaluate the intercalation process of organic cations int the clay structure. The organo - montmorillonites exhibited IR spectra giving evidence about sorption or intercalation of the alkylammonium cations. The enhancement of the basal spacing obtained by X-ray diffraction confirmed the intercalation process of cations into montmorillonite and vermiculite samples. Thermal behaviour of the modified clay minerals was investigated by simultaneous thermogravimetry and differential thermal analysis. The organically modified montmorillonites exhibited the higher values of temperatures related to the total melting. Also the temperatures of exotherm effects connected to recrystallization and transformation increased with the concentration of alkylammonium salts. The temperatures of dehydratation and dehydroxilation decreased with concentration of alkylammonium cations. Vermilulite samples showed generally reducing of their thermal stability.
Fulltext: content.csg -  PDF
Plný tet: UGN-0393204 - PDF
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Limitations of spectroscopic methods in the study of earthy pigments
Košařová, V. ; Hradil, David ; Kanický, V.
Nowadays, the spectroscopic methods, above all Infrared Spectroscopy (IR), are the most frequently used analytical methods in the research of cultural heritage, which is mainly caused by easy use and non-invasiveness of these methods and a broad range of their application, which comprises both organic and inorganic substances. Nevertheless, each analytical technique has its detection limits, and the fact that a particular method is suitable for one type of a sample does not automatically mean that it will be appropriate for the identification of another sample. Therefore, the aim of the study is to demonstrate the limitations of both Raman Spectroscopy (RS) and infrared spectroscopy in the study of earthy materials.
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Limitations of spectroscopic methods in the study of earthy pigments
Košařová, V. ; Hradil, David ; Kanický, V.
Nowadays, the spectroscopic methods, above all infrared spectroscopy (IR), are the most frequently used analytical methods in the research of cultural beritage, whitch is mainly cause by easy use and noninvasiveness of these metods and a broad range of thein application, which comprises both organic and inorganic substances. Therefore, the aim of the study is to demonstrate the limitations of both Raman Spectroscopy (RS) and infrared spectroscopy in the study of earthy materials.
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New kriteria for classification and differentiation between clay and iron oxide pigment sof various origins
Hradil, David ; Hradilová, J. ; Bezdička, Petr
Pigments containing iron, although they form a very large group, have never been considered very suitable for datation of color layers and identification of the origin of the painting, due to their abundant occurrence in nature, good availability and widespread use in all historical and pre-historical periods of time. In this paper we have verified that mineralogical composition of clay minerals in earthy pigments is a suitable tool for more detailed specification of material provenance and, in the case of ground layers, also the provenance of the artwork as such. It was obviously convenient to preferably use raw materials from a close and thus also cheaper source. For the purposes of statistical comparison we evaluated elemental composition of earthy grounds on 70 paintings from the 16(th)-18(th) centuries from Czech collections. We performed detailed mineralogical analyses for a selected representative number of grounds on 35 samples in total. We discerned 6 types of material in total 2 types of boles, 3 types of other earths, and one type representing iron-rich red from oxidized zones of hydrothermal ore deposits. We were able to distinguish between earthy pigments of Central European origin (coming from Czech and Bavarian locations) and those coming from North-Italian sources. Thus we were able to assign anonymous paintings to an appropriate place of origin.
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New kriteria for classification and differentiation between clay and iron oxide pigment sof various origins
Hradil, David ; Hradilová, J. ; Bezdička, Petr
Pigments containing iron, although they form a very large group, have never been considered very suitable for datation of color layers and identification of the origin of the painting, due to their abundant occurrence in nature, good availability and widespread use in all historical and pre-historical periods of time. In this paper we have verified that mineralogical composition of clay minerals in earthy pigments is a suitable tool for more detailed specification of material provenance and, in the case of ground layers, also the provenance of the artwork as such. It was obviously convenient to preferably use raw materials from a close and thus also cheaper source. For the purposes of statistical comparison we evaluated elemental composition of earthy grounds on 70 paintings from the 16(th)-18(th) centuries from Czech collections. We performed detailed mineralogical analyses for a selected representative number of grounds on 35 samples in total. We discerned 6 types of material in total 2 types of boles, 3 types of other earths, and one type representing iron-rich red from oxidized zones of hydrothermal ore deposits. We were able to distinguish between earthy pigments of Central European origin (coming from Czech and Bavarian locations) and those coming from North-Italian sources. Thus we were able to assign anonymous paintings to an appropriate place of origin.
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Pedogenesis of the Territory of Prague Affected by Human Activity
Žigová, Anna ; Šťastný, Martin
Soil cover affected by human activity in Prague is found generally in areas with loess deposits. Sites with different types of anthropogenic load, about 6 km apart, were selected for the study of pedogenesis. Soil profile of the first characteristic sequence was buried beneath a landfill layer 2,5 m thick. In the second sequence, the top part of the soil profile was affected by human activity. Characteristics of pedogenesis were determined using grain-size distribution, pH values, contents of CaCO3, Cox, Nt, cation exchange capacity and clay mineral contents. The character of pedogenetic processes was affected by anthropogenic factor to a variable degree. Lower influence on pedogenesis was encountered in the sequence with soil profile buried beneath a landfill layer.
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Soil cover of Přední Kobyla site (Bohemian Karst) genesis: role of clay minerals
Žigová, Anna ; Šťastný, Martin
Soil cover of Přední Kobyla site (Bohemian Karst) is represented by relict soils. Přední Kobyla site is covered by illimerized brown earthifield terra fusca with slight sings of pseudogleization. Fractions 0.01 mm and 0.001 mm from the soil profile are charakterized mainly by kaolinite, illite and quartz. Stage and distribution of plagioclase and feldspar in soil reflect the strong weathering process. In association with clay minerals kaolinite is dominant.
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