Recursos Minerais - RM
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- 3D predictive modelling using Artificial Neural Network Analysis in the Neves-Corvo deposits [Resumo]Publication . Batista, Maria Joao; Represas, Patricia; Carvalho, João; Araújo, Vítor; Marques, Fábio; Xavier Matos, João Manuel; Morais, Igor; Albardeiro, Luís; Inverno, Carlos; de Oliveira, Daniel Pipa Soares; Dias, P.ABSTRACT: This study focuses on mineral and lithological vectoring to target new VMS deposits in the Neves-Corvo district, Portugal. Neves-Corvo is a world-class deposit in the Iberian Pyrite Belt, discovered in 1977 by ground gravity survey and one of Europe’s important copper-zinc producers. The deposit is hosted in volcano-sedimentary sequences within a moderately folded and thrust-faulted setting. Previous studies show differences between massive sulphide ores and stockwork ores, especially in trace-element associations. These geochemical particularities, combined with decades of exploration data, make the area well suited for advanced statistical and multivariate analysis. This study will apply an Artificial Neural Network Analysis (ANNA) methodology to the geochemical data, interpolated from boreholes, and a 3D rock density model, obtained by a constrained inversion of gravity data, to identify patterns that other methods might overlook, thereby improving targeting for new VMS mineralization. ANNA can extract trends from complex datasets and perform non-parametric analysis that do not assume a-priori relationships between variables. Therefore, instead of relying on linear or quadratic regressions approaches, this study employs the so-called black box to determine a mathematical function that can adequately approximate the representation of dependent and independent variables. In this study, the number of variables is considerably smaller than the number of training cases available. The training progresses iteratively, using the previous outputs to carefully and progressively adjust the predictors in an iterative manner, allowing for a continuous validation (based in a set of data taken from the total data before training to monitor the performance of the training in each cycle or iteration) of the different scenarios. The geological model was produced, and the drill-hole density database was used to constrain the 3D gravity inversion. All information was laid in a 5mx5mx5m 3D mesh, eliminating the blocks with missing data. The formatted data was then inputted into in STATISTICA’s ANNA software. The variables considered for the first step of ANNA were Cu, Zn, rock density, gravity inversion and Cu/Zn ratio for the Lombador, Neves Graça, Corvo and Zambujal deposits. From the training and validation procedures, it was possible to conclude that using gravity inversion as target and Cu/Zn and rock density as input data produced the more accurate prediction map.
- Characterization and recovery of critical raw materials using innovative techniques – case study of the XTRACT project: São Domingos Mine, Portugal [Resumo]Publication . Morais, Igor; Solá, A. Rita; Albardeiro, Luís; Silva, Teresa; Hedrich, Sabrina; Vargas, Sergio Alejandro Camargo; Sáez Blázquez, Cristina; Almeida, Bruno; Kuusiniemi, Pasi; Arancibia, MarioABSTRACT: The Iberian Pyrite Belt (IPB) is one of the world’s most significant provinces of Volcanogenic Massive Sulfide (VMS) deposits, hosting both world class orebodies and medium sized systems such as the São Domingos Mine. This deposit consists of a steeply dipping, E–W elongated mass of cupriferous pyrite with associated zinc and lead sulfides, emplaced within a tectonically complex volcanic sequence overlain by thick turbidites and the allochthonous Phyllite Quartzite Group. Historical exploitation from the mid 19th to the 20th century, involving incineration, smelting, heap leaching and cementation, generated extensive waste dumps, slags and leaching piles. These materials remain enriched in potentially toxic elements (Zn, Pb, Sb, Cu, As, Hg, Cd), and ongoing sulfide oxidation and Fe hydrolysis promote acid mine drainage, enhancing metal mobility and creating persistent environmental contamination hotspots. Modern assessment of these legacy wastes requires advanced analytical and monitoring technologies. High resolution geochemical mapping, supported by drone based remote sensing, enables precise delineation of critical raw material enrichment zones and accurate estimation of waste volumes and tonnage. Emerging geophysical tools, including the Airborne Geophysical Electromagnetic System and integrated ground and air borne remote sensing platforms for tailings content assessment, provide detailed subsurface information on conductivity, internal heterogeneity and structural controls. Muon tomography offers unique density imaging capabilities for detecting cavities, collapse zones and remnant sulfide bodies in inaccessible areas. For sustainable metal recovery, bioleaching technologies represent an eco-efficient approach capable of mobilizing Cu, Zn, Co and other strategic elements from low grade materials. The integration of these state-of-the-art methodologies positions São Domingos as an exemplary natural laboratory for developing innovative strategies in mine waste valorization and environmental risk mitigation, directly supporting the overarching objective of the XTRACT project: establishing a sustainable ecosystem for innovative resource recovery and complex ore extraction within a low impact, circular economy mining paradigm.
- Chemical and Mineralogical Characterization ofWaste from Abandoned Copper and Manganese Mines in the Iberian Pyrite Belt, Portugal: A First Step Towards the Waste-to-Value Recycling ProcessPublication . de Oliveira, Daniel Pipa Soares; Silva, Teresa; Morais, Igor; Fernandes, JoãoABSTRACT: This study examines the chemical and mineralogical composition of waste materials from abandoned copper and manganese mines in the Iberian Pyrite Belt, Portugal, as a first step toward their potential recycling for critical and strategic raw materials (CRM and SRM). Using portable X-ray fluorescence (pXRF) and other analytical techniques, this research highlights the presence of valuable elements, including copper, manganese, and rare earth elements, in concentrations significantly above their crustal abundance. The findings underscore the dual potential of these wastes: as sources of secondary raw materials and for mitigating environmental hazards such as acid mine drainage (AMD). Recovered materials include chalcopyrite, pyrolusite, and rhodochrosite, with critical elements like cobalt, lithium, and tungsten identified. pXRF proved to be a reliable, cost effective tool for rapid field and laboratory analyses, demonstrating high precision and good correlation with standard laboratory methods. The study emphasizes the importance of characterizing historical mining waste to support a circular economy, reduce reliance on foreign material imports, and address environmental challenges. This approach aligns with the European Union’s Critical Raw Materials Act, promoting sustainable resource use and the recovery of strategic resources from historical mining sites.
- Geochemical and mineralogical characterization of manganese deposits in the Iberian Pyrite Belt - preliminary study [Resumo]Publication . Morais, Igor; Albardeiro, Luís; Silva, Teresa; de Oliveira, Daniel Pipa SoaresABSTRACT: The Iberian Pyrite Belt (IPB), traditionally recognized for its extensive volcanogenic massive sulfide deposits, also hosts a diverse set of manganese (Mn) occurrences whose genesis remains comparatively less explored. These deposits, distributed across distinct stratigraphic and structural contexts, represent an important record of the paleoenvironmental evolution and metallogenetic processes that shaped the region. In this preliminary study, several typologies of Mn deposits were sampled and analyzed, including stratiform levels interbedded within volcano sedimentary sequences, hydrothermal alteration zones peripheral to VMS systems, and horizons enriched through supergene processes associated with intense sulfide weathering. This diversity of geological settings allowed the assessment of internal variability within the deposits and the identification of the main geological controls governing Mn concentration. Mineralogical characterization revealed the presence of multiple primary and secondary phases, including oxides, hydroxides, carbonates, silicates and amorphous Mn–Fe–rich materials, as well as alteration products formed under oxidizing conditions. This mineralogical complexity indicates that Mn deposits in the IPB do not result from a single process, but rather from the interaction between hydrothermal, sedimentary and supergene mechanisms. From a geochemical perspective, the samples exhibit high Mn contents accompanied by significant concentrations of Fe, Ba and Si, in addition to trace elements that act as sensitive indicators of paleoenvironmental conditions. The observed geochemical relationships point to depositional environments influenced by low temperature hydrothermal circulation, accumulation in restricted basins under reducing conditions, and subsequent enrichment through oxidation and supergene leaching. These patterns are consistent with hybrid metallogenetic models characteristic of Mn enriched VMS systems. Overall, the results highlight the substantial typological variability and the mineralogical and geochemical complexity of Mn deposits in the IPB, reinforcing both their scientific relevance and their economic potential in the context of the energy transition. Future work should integrate isotopic analyses and high-resolution textural investigations to further elucidate the evolution of these deposits and their potential for resource development.
- Geochemistry of historical smelting slags from S. Domingos (Iberian Pyrite Belt) and implications for metal recovery [Resumo]Publication . Silva, Teresa; Morais, Igor; Albardeiro, Luís; Solá, A. Rita; de Oliveira, Daniel Pipa SoaresABSTRACT: The historical mining area of S. Domingos, located in the Iberian Pyrite Belt (IPB), southwestern Portugal, hosts significant accumulations of mining wastes including, smelting slags, iron oxides, milled blocks of pyrite and other residues resulting from centuries of processing Cu-rich massive sulfide ores. Polymetallic sulfide exploitation in this region dates to pre-Roman times and continued until 1966. These slags represent an important record of historical metallurgical practices and a potential secondary resource for critical and strategic raw materials (CRM/SRM) and other valuable metals. This study investigates the geochemical composition and mineralogical characteristics of historical smelting slags, to access not only their potential to metal recovery, but also their associated environmental risks. The slags are heterogeneous and chemically unstable waste products, typically Fe-rich, and dominated by fayalite, Fe2+2SiO4 (the iron-rich member of the olivine mineral group) together with glassy matrices. Fayalite is the result of the reaction of iron oxide with silica at high temperatures and host a range of metals including As, Ba, Co, Cu, Sn, Pb, Sr and Zn. Weathering processes promote metal mobilization of these elements, contributing to local contamination and to the development of acid mine drainage (AMD) products in the surrounding areas. Geochemical assessment indicates that significant quantities of valuable metals remain trapped within these historical slags due to inefficient recovery during earlier smelting technologies. Studies across the IPB suggest that mining wastes may contain significant valuable reserves of metals such as Fe, Zn, Cu and Pb, as well as CRM and other important trace metals. Consequently, these residues represent potentially promising targets for reprocessing using advanced metallurgical or hydrometallurgical technologies. Detailed geochemical characterization provides insights supporting the development of sustainable recovery strategies within a circular economy framework for historic mining districts of the Iberian Pyrite Belt. The results underscore the dual importance of recovering the S. Domingos slags as potential secondary mineral resources, while also mitigating the environmental impact associated with AMD.
- Mapping critical raw materials in Portugal [Resumo]Publication . de Oliveira, Daniel Pipa Soares; Gonçalves, Pedro; Filipe, Augusto; Santos, Sara; Albardeiro, Luís; Morais, Igor; Xavier Matos, João Manuel; Salgueiro, RuteABSTRACT: Reliable and secure access to Critical and Strategic Raw Materials (CRM/SRM) is a strategic requirement for the European Union, underpinning industrial competitiveness, technological innovation, and the transition toward a climate-neutral economy. In response to increasing supply risks, high import dependency, and growing demand driven by renewable energy systems and e-mobility, this work presents the second Critical Raw Materials Deposits Map of mainland Portugal, compiled at a scale of 1:700000. The map integrates geological, spatial, and mineral resource data derived primarily from the SIORMINP database (Information System of Portuguese Occurrences and Mineral Resources), developed and maintained by LNEG. This database currently contains over 2453 documented mineral occurrences, including 1214 strategic and critical mineral occurrences associated with EU-defined critical raw materials, which were systematically identified and evaluated. Key commodities represented include tungsten, lithium, antimony, titanium, rare earth elements, cobalt, tantalum-niobium, feldspar, nickel, and copper, among others. The systematic integration of these datasets provides a robust framework for national and European-scale mineral intelligence. A comprehensive scientific and cartographic methodology was applied, combining official geological mapping, the tectonostratigraphic domains of the Iberian Massif, and shaded-relief terrain visualization. The mineral occurrences were classified according to deposit type, size, structural orientation, and mineralization source, allowing visualization of both spatial distribution and metallogenic context. Cartographic design followed established visual variables theory to convey multidimensional geological information while maintaining clarity at the chosen scale. The resulting map represents a significant advance in national mineral intelligence, supporting mineral exploration targeting, resource assessment, land-use planning, and evidence-based policy decision-making. It also contributes to pan-European datasets, promoting data harmonization and international comparability. Conceived as a dynamic product, the map is designed to be periodically updated in line with revisions to the EU Critical Raw Materials list. Overall, this work demonstrates the value of integrated geological and cartographic approaches in strengthening raw material supply knowledge at both national and European scales.
- Mineralogical and Geochemical Characterization of Geological Materials, 2nd EditionPublication . Silva, Teresa; de Oliveira, Daniel Pipa Soares; Veiga, João PedroABSTRACT: This Special Issue reinforces the strategic role of mineralogical and geochemical characterization in tackling key scientific challenges associated with mineral resources, providing essential insights into ore genesis, mineral processing, environmental performance, and the sustainable supply of raw materials. The topics demonstrate how advanced analytical techniques and multidisciplinary approaches are improving knowledge of geological materials and Earth processes while supporting sustainable resource management, environmental protection, and cultural heritage conservation. Studies on lithium-bearing pegmatites, mining waste, and abandoned mine sites showcase the manner in which detailed mineralogical and geochemical research is able to uncover new resource opportunities, promote circular economy practices, and support responsible resource recovery. Contributions also explore applications in geoheritage and heritage conservation, including the use of geopolymers as sustainable restoration materials and the assessment of natural stones for monument preservation. Furthermore, environmental studies address soil geochemistry, environmental monitoring, and occupational health through innovative mineral and particle characterization methods. Several papers showcase cutting-edge analytical tools, including Raman spectroscopy, SEM-EDS, LA-ICP-MS, and ToF-SIMS, highlighting advances in analytical accuracy, efficiency, and data interpretation. This reprint provides an important reference resource for researchers working across Earth and materials sciences.
- New Contributions to Mineralogical and Geochemical Knowledge of Old Preguiça Mine, Beja, PortugalPublication . Silva, Teresa; Morais, Igor; Mesquita Soares, Sofia; Rodrigues, Ivo; de Oliveira, Daniel Pipa Soares; Mirao, JoseABSTRACT: Abandoned mining areas provide valuable opportunities to investigate ore-forming processes, supergene mineral transformations, and the geochemical behaviour of metals. In this sense, the old Preguiça mine (Beja, Portugal), exploited for Fe–Zn–Pb, was studied providing new mineralogical and geochemical data aimed at improving the understanding of the secondary mineral assemblages of this deposit. A total of 70 samples collected from three accessible underground levels (first, second and third) and mine waste, complemented by 16 samples from a deeper level (fourth) previously collected, were analysed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and a portable X-ray fluorescence (pXRF) equipment. Mineralogical phases are dominated by a wide range of secondary oxides, carbonates, arsenates, vanadates, silicates, phosphates and sulphates, but remnants of primary sulphides were also found. The following minerals can be emphasised: goethite, hematite, calcite, dolomite, descloizite, willemite, mimetite, cerussite, smithsonite and fraipontite. The presence of massicot in the Preguiça mine, is described for the first time. Bulk geochemical analyses show high concentrations of Fe, Ca, Zn and Pb, consistent with the observed mineralogy. The presence of vanadium- and arsenic-bearing minerals highlights the occurrence of critical raw materials, supporting the importance of reassessing other abandoned mining areas in the context of sustainable resource management and strategic raw-material planning.
- Preliminary Integrated Analysis of Magnetic Susceptibility, Geochemistry, and Mineralogy in the Neves Corvo VMS District (MAQSIMAL Project)Publication . Represas, Patricia; Batista, Maria Joao; Albardeiro, Luís; Marques, Fábio; Silva, Teresa; Carvalho, João; Xavier Matos, João ManuelABSTRACT: The MAQSIMAL project develops a multimodal airborne quantum-sensor prototype that simultaneously measures the 3D magnetic field, magnetic-field gradients and electromagnetic responses to improve sustainable mineral exploration. The Neves–Corvo mining district (Iberian Pyrite Belt, Portugal), a largely concealed volcanogenic massive sulphide (VMS) system, was selected as a test site to compare prototype data with existing geological and drilling information. This extended abstract reports initial surface-sample characterisation integrating magnetic susceptibility (KT-10; ∼150 outcrops), XRD mineralogy and portable XRF geochemistry (20 samples). Susceptibility values are strongly right-skewed (0–5.81×10−3 SI) and vary systematically with lithology: mafic volcanic rocks show the highest and most variable responses, whereas felsic volcanic, sedimentary and strongly sericitic/argillic rocks are consistently magnetically weak, consistent with magnetite destruction and/or dilution during alteration. XRD identifies alteration minerals (chlorite, sericite, kaolinite) and pXRF data differentiate mafic versus metasedimentary compositions and show a moderate sample-scale correlation between susceptibility and total Fe (r≈0.49). The combined datasets provide an internally consistent basis for early sensor calibration and motivate expanded paired sampling and spatial mapping to better link surface signatures with subsurface VMS-related lithologies and alteration.