Mineralogical transformations of calcareous rich clays with firing: A comparative study between calcite and dolomite rich clays from Algarve, Portugal

Trindade, M.J.; Dias, María Isabel; Coroado, João; Rocha, Fernando

doi:10.1016/j.clay.2008.02.008

Cited by 274 publications

(168 citation statements)

References 17 publications

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“…The absence of illite and the presence of gehlenite, wollastonite and, in a lower extent, anorthite and diopside in the samples is a consequence of the reactions occurring when calcium or magnesium-rich clays are fired above 900ºC. 27,42,43,45,47 Because gehlenite starts to be developed from 800ºC, 48 its coexistence with illite, micas and calcite on both Tarraconensian sherds (Fig. 4e-f), suggests firing temperatures of around 800ºC.…”

Section: X-ray Diffraction (Xrd)mentioning

confidence: 99%

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Archaeological ceramic amphorae from underwater marine environments: Influence of firing temperature on salt crystallization decay

López-Arce

Zornoza-Indart

Gomez-Villalba

et al. 2013

Journal of the European Ceramic Society

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Non-desalinated and desalinated fragments of Iberian, Italic and Tarraconensian amphorae sherds, found in different underwater marine environments, were compared to determine both their state of conservation and the decay caused by salt crystallization. Polarizing light and fluorescence optical microscopy, scanning electron microscopy coupled to energy dispersive X-ray spectroscopy, X-ray diffraction, ion chromatography and mercury intrusion porosimetry tests were conducted on the samples. Non-desalinated samples or samples in which desalination was not wholly effective exhibit a variety of signs of degradation, especially in those samples fired at lower firing temperature. Sherds fired at higher temperatures have lower surface area and less connected porosity, which entail a lower absorption of soluble salts containing water and eventually less decay. The composition and texture reached with the firing temperature is a key factor on salt crystallization decay and hence on the durability of these artifacts. This should be taken into account during desalination procedures that have to be optimized in order to be successful.

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Section: X-ray Diffraction (Xrd)mentioning

confidence: 99%

“…These findings may be indicative of a firing temperature of over 900ºC. 27,[40][41][42] The presence of micas (biotite and muscovite), illite and some calcite in A-Ibe-31 (Fig. 4b), in turn, would denote much lower firing temperatures, under 800ºC 5,27,43 .…”

Section: X-ray Diffraction (Xrd)mentioning

confidence: 99%

Archaeological ceramic amphorae from underwater marine environments: Influence of firing temperature on salt crystallization decay

López-Arce

Zornoza-Indart

Gomez-Villalba

et al. 2013

Journal of the European Ceramic Society

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“…However, the identified phases (gehlenite-quartz-wollastonite) correspond to non-equilibrium phases, indicating that the heat treatment time and/or temperature were insufficient to reach equilibrium. These results are (Peters & Iberg, 1978;Kreimeyer, 1987;González García et al, 1988;Sanjad et al, 2004;Trindade et al, 2009). …”

Section: Resultsmentioning

confidence: 49%

Chemical and mineralogical characterization of portuguese ceramic tiles in the historic center of São Luís do Maranhão (Brazil): an approximation of the mineralogy and firing temperature of the raw materials

Mercury

Pereira²,

Vasconcelos

et al. 2013

Rem: Rev. Esc. Minas

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Nesse trabalho, foram caracterizados, pela primeira vez, azulejos históricos portugueses do Centro Histórico de São Luís (CHSL) do Maranhão. A caracterização foi realizada através dos ensaios de microscopia ótica, difração de raios X (DRX) e análise química, visando ao uso dessa informação para a determinação das possíveis matérias-primas utilizadas na sua fabricação, bem como a provável temperatura de queima desses materiais. Os resultados mostraram que a microestrutura desses materiais é constituída por poros de tamanhos variados, apresentando incrustações de calcita e grãos de quartzo de tamanhos inferiores a 500 µm, distribuídos numa matriz de cor rosa-amarelo, onde foram identificadas, por DRX, as fases minerais calcita, gelhenita, wollastonita, quartzo e amorfo. A partir da informação obtida, é possível inferir que as matérias-primas originais estiveram constituídas, provavelmente, por mistura de argilas caoliníticas (Al 2 O 3 ·2SiO 2 ·2H 2 O), ricas em carbonatos de cálcio e quartzo ou misturas de argilas caoliniticas, quartzo e calcita. Essas matérias-primas originais não atingiram a temperatura de cocção de 950ºC. Palavras-chave: Romulo Simões Angélica

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“…Consequently, most of the mineral constituents are instable with increasing temperature and suffer gradual transformations due to laboratory heating. The major reactions, which occur can be grouped in the following way: (a) loss of hydrated water; (b) dehydroxilation of clay minerals; (c) oxidation and solid state transformations of Fe-bearing minerals; (d) decomposition of CaCO 3 ; (e) high-temperature destruction of clays and formation of new phases (Rowland, 1955;Plante et al, 2009;Trindade et al, 2009). All these processes superimpose in the response of different physical properties of soils with increasing temperature.…”

Section: Discussion Thermomagnetic Analysis Of Magnetic Susceptibilitmentioning

confidence: 99%

Thermomagnetic Behavior of Magnetic Susceptibility—Heating Rate and Sample Size Effects

Jordanova

2016

Front. Earth Sci.

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Thermomagnetic analysis of magnetic susceptibility k(T) was carried out for a number of natural powder materials from soils, baked clay and anthropogenic dust samples using fast (11 • C/min) and slow (6.5 • C/min) heating rates available in the furnace of Kappabridge KLY2 (Agico). Based on the additional data for mineralogy, grain size and magnetic properties of the studied samples, behavior of k(T) cycles and the observed differences in the curves for fast and slow heating rate are interpreted in terms of mineralogical transformations and Curie temperatures. The effect of different sample size is also explored, using large volume and small volume of powder material. It is found that soil samples show enhanced information on mineralogical transformations and appearance of new strongly magnetic phases when using fast heating rate and large sample size. This approach moves the transformation at higher temperature, but enhances the amplitude of the signal of newly created phase. Large sample size gives prevalence of the local micro-environment, created by evolving gases, released during transformations. The example from archeological brick reveals the effect of different sample sizes on the observed Curie temperatures on heating and cooling curves, when the magnetic carrier is substituted magnetite (Mn0.2Fe2.70O4). Large sample size leads to bigger differences in Tcs on heating and cooling, while small sample size results in similar Tcs for both heating rates.

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Mineralogical transformations of calcareous rich clays with firing: A comparative study between calcite and dolomite rich clays from Algarve, Portugal

Cited by 274 publications

References 17 publications

Archaeological ceramic amphorae from underwater marine environments: Influence of firing temperature on salt crystallization decay

Archaeological ceramic amphorae from underwater marine environments: Influence of firing temperature on salt crystallization decay

Chemical and mineralogical characterization of portuguese ceramic tiles in the historic center of São Luís do Maranhão (Brazil): an approximation of the mineralogy and firing temperature of the raw materials

Thermomagnetic Behavior of Magnetic Susceptibility—Heating Rate and Sample Size Effects

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