The main objective of this work was to contribute to the knowledge of the geological resources of... more The main objective of this work was to contribute to the knowledge of the geological resources of Trás-os-Montes and Alto Douro (TMAD) region, in particular of its “Xisto” (Portuguese word for “schist”, lato sensum), considering its economic and social impact. The target area is characterized by the abundant occurrence of different types of “schist”, belonging to the Variscan basement. This work is a contribution to improve the knowledge about mineralogy, fabric, chemistry and technology of the “schist”, in order to promote its exploitation and use as a natural stone. It was possible to identify the main factors that have an influence on the characteristics of all types of “schist”, conditioning its use as natural stone.
Metaquartzite from Serra da Garraia and Zebras were studied. These rocks belong to the "Uppe... more Metaquartzite from Serra da Garraia and Zebras were studied. These rocks belong to the "Upper Quartzite Formation" of the “Parautochthonous Complex”. They are light grey and present, sometimes, a brownish patina. The quarries range from 2 to 10m high and 25 to 40m long. This study consists on the petrographic, chemical and physical-mechanical characterization of these rocks, aiming the determination of their potential as natural stone. The petrographic studies revealed that the rocks are formed by quartz and white mica and accessory opaque minerals (titanomagnetite, magnetite, and hematite) and zircon. The petrographic studies and SiO2 and Al2O3 values revealed a different evolution for Garraia and Zebras in terms of textural maturity and mineralogical differentiation. The studies allowed the distinction between quartzites and quartz phyllites. The physical-mechanical analyses attest that all the studied rocks can be used as natural stones.
The main purpose of this work was to increase the knowledge about the geological resources of Trá... more The main purpose of this work was to increase the knowledge about the geological resources of Trás-os-Montes and Alto Douro region (TMAD), particularly about their “schists” (slate, phyllite and schist), due to the economic and social effects that their mining and processing can have, not only on the local economy, but also on a national level. This work presents the results of the study conducted on “schists” from TMAD, aiming for their use as natural stone. Special emphasis is given on the results obtained from the following physical and mechanical tests: compressive strength, flexural strength, apparent density, open porosity, water absorption, abrasion resistance and resistance to ageing by thermal shock. These tests were determinant to define the most suitable applications for each schistose stone that was studied, taking into account the existing groups of natural stone products. For defining the recommended applications for each “schist”, European standards for natural stone ...
The main objective of this work was to contribute to the knowledge of the geological resources of... more The main objective of this work was to contribute to the knowledge of the geological resources of Trás-os-Montes and Alto Douro (TMAD) region, in particular of its “Xisto” (Portuguese word for “schist”, lato sensum), considering its economic and social impact. The target area is characterized by the abundant occurrence of different types of “schist”, belonging to the Variscan basement. This work is a contribution to improve the knowledge about mineralogy, fabric, chemistry and technology of the “schist”, in order to promote its exploitation and use as a natural stone. It was possible to identify the main factors that have an influence on the characteristics of all types of “schist”, conditioning its use as natural stone.
Metaquartzite from Serra da Garraia and Zebras were studied. These rocks belong to the "Uppe... more Metaquartzite from Serra da Garraia and Zebras were studied. These rocks belong to the "Upper Quartzite Formation" of the “Parautochthonous Complex”. They are light grey and present, sometimes, a brownish patina. The quarries range from 2 to 10m high and 25 to 40m long. This study consists on the petrographic, chemical and physical-mechanical characterization of these rocks, aiming the determination of their potential as natural stone. The petrographic studies revealed that the rocks are formed by quartz and white mica and accessory opaque minerals (titanomagnetite, magnetite, and hematite) and zircon. The petrographic studies and SiO2 and Al2O3 values revealed a different evolution for Garraia and Zebras in terms of textural maturity and mineralogical differentiation. The studies allowed the distinction between quartzites and quartz phyllites. The physical-mechanical analyses attest that all the studied rocks can be used as natural stones.
The main purpose of this work was to increase the knowledge about the geological resources of Trá... more The main purpose of this work was to increase the knowledge about the geological resources of Trás-os-Montes and Alto Douro region (TMAD), particularly about their “schists” (slate, phyllite and schist), due to the economic and social effects that their mining and processing can have, not only on the local economy, but also on a national level. This work presents the results of the study conducted on “schists” from TMAD, aiming for their use as natural stone. Special emphasis is given on the results obtained from the following physical and mechanical tests: compressive strength, flexural strength, apparent density, open porosity, water absorption, abrasion resistance and resistance to ageing by thermal shock. These tests were determinant to define the most suitable applications for each schistose stone that was studied, taking into account the existing groups of natural stone products. For defining the recommended applications for each “schist”, European standards for natural stone ...
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