Repositório do LNEG
Repositório Científico do Laboratório Nacional de Energia e Geologia
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Atlas of European ornamental stone resources
Publication . Heldal, Tom; Carvalho, Jorge; Dedić, Željko; Laskarides, Kostas
ABSTRACT: Ornamental stone is today a raw material produced with great skills all over Europe, SME's and larger enterprises exploiting the vast diversity of European ornamental stone resources. Today's European stone industry is not only large and important but also highly dispersed throughout Europe, making a backbone industry for particularly rural areas. In Italy alone, there are more than 1000 stone quarrying enterprises and the sector in total employed more than 50 000 in 2011.
Ornamental stone has contributed significantly in shaping our rural and urban landscapes, through its use in our built heritage from different historical periods. Yet, the actual use of local and regional stone resources in Europe is under threat due to sterilization of resources by urbanisation, infrastructure development and other land uses. Consequently, important resources are “unknowingly” lost for future production, and so are vital geological knowledge and skills for producing them. Loss of such resources will not only make it more difficult to maintain and restore our architectural heritage, but also prevent the use of traditional materials in the future.
Sustainable exploitation of ornamental limestones in Maciço Calcário Estremenho, Portugal
Publication . Carvalho, Jorge; Lisboa, Jose
ABSTRACT: The Maciço Calcário Estremenho, in Portugal, is a limestone massif where an intense extraction activity of limestone blocks for ornamental purposes takes place in five main quarry clusters. A large extent of this massif, including the exploitation centers, is covered by the Natura 2000 Network PTCON0015 site, which simultaneously corresponds to the Portuguese Natural Park of Serras de Aire e Candeeiros. As a result of the restrictive measures imposed by the regulations for the protection of nature, conflicts with the extractive industry have persisted for decades. The present case-study demonstrates that through the dialogue between the extractive industry and the public entities responsible for nature conservation and spatial planning, it is possible to find compatibility solutions that consider the territory’s aptitude for the exploitation of mineral deposits and the need to preserve relevant environmental values. For that purpose, an unprecedented partnership between the environmental authority and an association representative of the extractive sector carried out detailed geological and environmental studies that resulted in a land-use planning proposal for each of the quarrying areas.
These proposals make it possible to reconcile extraction with the protection of outstanding biological values and geological heritage.
Preliminary Ornamental Classification of Biotitic Granites from Cubal (SW of Angola)
Publication . Lisboa, Jose; Caessa, Paulo; Lopes, R.; Oliveira, Álvaro; Silva, Paulo Bravo; Fernández, J.; Rodrigues, José Feliciano; Manuel, José
ABSTRACT: In the Cubal region between Benguela and Huambo (SW of Angola), grey biotite granites of middle Paleoproterozoic age occur on a planation surface as residual reliefs, either of inselberg or inselgbirge type. The objective of this work is to carry out the preliminary classification of the grey granites of the Cubal region (SW of Angola), ranking the areas in relation to their potential in granites as ornamental rocks. Six granite lithotypes were identified, which can be grouped into 3 sets according to their textural characteristics. The petrographic analysis reveals that from a mineralogical point of view, granitic lithotypes are very similar with a significant content of plagioclase. The samples chemical analysis shows a homogeneous acidic composition in the granite composition range. Tests were carried out to determine real and apparent density, total and open porosity, water absorption at atmospheric pressure, compressive strength, and bending strength. The results show that the Cubal granites have the characteristics of quality ornamental stones, which in general can be used in all types of applications, in interior and exterior environments. Based on a set of variables, an empirical classification of the ornamental potential of the granites was made, where 4 levels of increasing potential in the study area are established.
Maps of Industrial Rocks and Minerals of Angola: CARMINA Project. Products obtained and main results
Publication . Fernández, J.; Lisboa, Jose; Iglesias-Martínez, Mario; Gumiel, J.C.; Feria, María Carmen; Francés, Alain Pascal; Merino-Martinez, Enrique; Manuel, José; Garcia-Lobon, Jose Luis
ABSTRACT: Recognizing the pivotal role of the sector in the socioeconomic development of the nation, the Government of the Republic of Angola has actively endorsed the establishment of a geological-mining cartography. This initiative, employing modern methodologies, is a fundamental tool for strategically planning mineral resource exploitation. The outcomes of this initiative underscore the remarkable diversity of substances and the considerable significance of the studied deposits. In the domain of Industrial Rocks and Minerals, specifically within the CARMINA subprogram, a comprehensive compilation of 30 geological-mining maps has been generated. These maps delineate Areas of Mining Potential, and are accompanied by corresponding reports that encapsulate the research findings and technical-analytical outcomes of the investigated regions. The undertaken efforts have unveiled the substantial potential for Natural Stone, featuring novel varieties of granites, marbles, and “exotic” rocks such as amazonites, sodalites, pegmatites, and carbonatites. The last refered rock types are particulary interesting since they serve as sources for industrial rocks and minerals, encompassing valuable resources like lithium and Rare Earths. Thus, these resources exhibit promising prospects in the context of the energy transition. Additionally, noteworthy deposits include high-purity quartz in Equimina region, feldspars in Giraúl area, kaolins and clays within the Cunene Anorthositic Complex. The systematic creation of mineral resource maps, along with the associated research, contributes to the provision of up-to-date information regarding the geological-mining potential of the studied territory.
The historical archive of LNEG slides collection of national scientific value - LAMINOTECA 1.0
Publication . Pereira, Zélia; Quental, Lídia; Jorge, Micael; Teixeira, Rui; Patinha, Pedro; Xavier Matos, João Manuel; Mesquita Soares, Sofia; Silva Mendes, Márcia Cristina; Pereira, Aurete; de Oliveira, Daniel Pipa Soares; Matos, Maria Luísa; Carvalho, Cristina Isabel Paulo; Dias, Ruben
ABSTRACT: The historical archive of the Laboratório Nacional de Energia e Geologia (LNEG) encompasses nearly 180 years of geological and mining activity, constituting an exceptional scientific repository and a national geological treasure. Among LNEG’s core missions is the preservation, processing, and dissemination of this unique heritage. The collection is recognised as part of the national scientific heritage, holding both historical and strategic importance for research and possessing considerable economic value. However, the existing collections must be properly organized and digitized to ensure their online accessibility through the LNEG GEOPORTAL platform. Achieving this goal requires the creation and development of a digital data centre that will facilitate and promote the consultation of the existing information. One of the archives in greatest need of urgent organization is the collection of rock thin sections and polished surfaces, which includes thousands of specimens preserved at LNEG. These materials are the result of decades of petrographic studies of rocks, fossils, and ores conducted across Portugal and its former overseas territories (now CPLP countries). The slides and polished surfaces are essential for rock characterisation, and their petrographic analysis provides invaluable support across multiple LNEG mission areas.