Caracterização mineralógica de azulejos de Salvador e Belém dos séculos XVI, XVII e XIX

Abstract

O presente artigo trata da caracterização da composição mineralógica de azulejos antigos pertencentes aos séculos XVI, XVII e XIX, coletados em Salvador e Belém, visando à identificação da sua provável matéria-prima e a possível temperatura de queima. Quartzo foi identificado em todas as amostras. As demais fases cristalinas encontradas foram: mullita, cristobalita, calcita, anortita, hematita, gehlenita, diopsídio e wollastonita. Foi possível dividir as amostras em três grupos, em função da possível matéria-prima e temperatura de queima: grupo 1 - caulinita e quartzo, T entre 1200º e 1728º C; grupo 2 - quartzo, caulinita, calcita e/ou dolomita e óxido ou hidróxido de ferro, T entre 900º e 1200ºC; grupo 3 - quartzo, argilominerais (provavelmente caulinita), calcita e/ou dolomita e hidróxido ou óxido de ferro, T entre 1200º e 1565º C.<br>The present article is a study about the mineralogical composition of ancient tiles from centuries XVI, XVII and XIX, found in Belém and Salvador, in order to interpret the possible raw material and burning temperature. Quartz was identified in all samples. Other crystalline phases found are mullite, cristobalite, calcite, anorthite, hematite, gehlenite, diopside and wollastonite. Based on the probable raw material and probable burning temperature it was possible to organize the samples into three groups: group 1 - kaolinite and quartz, T between 1200º and 1728º C; group 2 - kaolinite, calcite and/or dolomite and iron oxide or hydroxide, T between 900º e 1200ºC; group 3 - quartz, clay minerals (probably kaolinite), calcite and/or dolomite, iron oxide or hydroxide, and T between 1200º e 1565º C

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

“…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). …”

“…• Re-carbonation of un-reacted CaO present in the core of the ceramic tile with CO2 coming from air (Ramos et al, 2002;Sanjad et al, 2004;Coroado and Gomes, 2011;Pereira et al, 2011). (Ramos et al, 2002;Sanjad et al, 2004;Coroado and Gomes, 2011;Pereira et al, 2011).…”

“…(Ramos et al, 2002;Sanjad et al, 2004;Coroado and Gomes, 2011;Pereira et al, 2011). Based on the XRD results and the content of primary oxides (CaO, SiO 2 and Al 2 O 3 ) detected in the chemical analysis, the approximate composition of the tiles can be recalculated, as shown in the CaOAl 2 O 3 -SiO 2 ternary equilibrium phase diagram illustrated in Figure 4.…”

The historical glazed tiles from Nossa Senhora da Soledade Cemetery, Northern Brazil: microstructural, physical and mineralogical characterization

“…These defects can even be caused by retraction fissures or presence of organic matter in the paste, which also release CO 2 during firing [4]. The relation between the volume of voids and the total volume of the sample in the ceramic material, verified by the results of the absorption test, indicate an average porosity if compared with the results obtained in another study with 20 tiles produced in the sixteenth, seventeenth and nineteenth centuries showing variations from 9.32 to 42.30% [18]. There is a higher percentage of voids in samples AZ.B25, AZ.I14, AZ.18, AZ.N33, AZ.P3 and the opposite in samples AZ.C11, AZ.F11, AZ.H7, AZ.M5.…”

“…Ceramic layer: the production of Portuguese tiles in the nineteenth century, in general, still used rudimentary techniques and raw materials, which directly affected the quality of the product, such as its porosity [15,16]. The result of this production process is observed in the heterogeneity of the ceramic layer of Soledade tiles.…”