Cristina Carvalho

Evaluation of the Portuguese Ornamental Stone Resources

Portugal produces a great diversity of ornamental stones. Besides the internationally known white and pink marbles, also light cream limestones are produced, as well as grey, yellow and pink granites, and dark grey slates. A first exercise is presented on the evaluation of the available resources of ornamental stones in the whole Portuguese territory. The results show a total availability of 410 million cubic meters, of which 274 million refer to granite, 76 million to limestone, 51 million to marble, and 9 million to slate.

Schist from Trás-os-Montes and Alto Douro (NE of Portugal): Potential Use as Natural Stone

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 products were considered, as well as technical specifications that exist in some European countries, which were the basis for the establishment of a proposal of technical specifications for Portugal, already published by one of the authors of this work.

Characterization of "Xisto" as a Way to Promote its Use as Natural Stone

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.