Comunicações Geológicas
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Percorrer Comunicações Geológicas por Domínios Científicos e Tecnológicos (FOS) "Ciências Naturais::Outras Ciências Naturais"
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- Gemological analysis of ruby origins: a case studyPublication . Oliveira, Isaac Gomes de; Cardoso, Jessica de Sousa; Franco, Julia; Santos, Breno Ravielly dos; Silva, Suely Andrade da; Santos, Lucilene; Mattos, Irani Clezar; Neri, Tereza Falcão de OliveiraABSTRACT: Gemstones are substances of natural, artificial or synthetic origin, which due to their hardness, rarity, uniqueness, diaphaneity and beauty are used as adornments. In the market, ruby is the second most expensive type of gemstone. Depending on its size, it can exceed the value of the diamond, besides being the most valuable colored gem in the market. It is a variety of the mineral corundum, just like sapphire, and it is a form of crystallized alumina (Al2O3) and the responsible for its red color is chromium. There are deposits in many different places around the world, being common the practice of speculating the origin of the ruby based on the shade of red. Provenance strongly impacts the commercial value of the gem. Several faceted rubies were donated to the Federal University of Ceará. This project aims to discover from what regions (countries) the donated rubies are coming, using gemological characteristics. To establish the origin of the specimen collection, the following methods and equipment were used: bibliographic research about rubies characteristics, refractometer to measure refractive indexes, dichroscope for pleochroism analysis, ultraviolet lamp (UV) for determination of fluorescence, and especially the gemological (stereoscopic) microscope to study the types of inclusions in transparent to translucent rubies. Using the methods cited, it was possible to produce, successfully, the gemological characterization of the specimens and deduce, based on strong evidence, what was the geographic origin of the studied specimens. Through microscopy it was deduced that all the faceted stones are natural and the whole collection include stones from the following countries: Burma, Thailand, Pakistan, Sri Lanka and Tanzania. Results are gathered systematizing bibliographic data and analytical results in order to identify the country of origin of the rubies.
- Magnetic characterization of non-geological materials: implications on human healthPublication . Diogo Sá; Cruz, Cláudia; Sant'Ovaia, HelenaABSTRACT: This study investigates the magnetic properties of commonly used non-geological materials and evaluates their potential implications for human health. The analyzed materials include tobacco and its by-products (filters and ashes), industrial paints, hair dyes and developer, garage dust, fuel soot and metal scarps. A multi-analytical approach combining optical microscopy, scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), X-ray fluorescence (XRF), and magnetic techniques (magnetic susceptibility, χ, isothermal remanent magnetization, IRM, and thermomagnetic curves, K/T) was applied to identify and characterize iron-bearing phases. Iron oxides were detected in several materials, particularly tobacco, ashes, used filters, fuel soot, garage dust and metal scraps. Tobacco ash and fuel soot samples contained ultrafine iron-rich particles (~2 μm), which are small enough to be inhaled, penetrate pulmonary alveoli, and potentially enter the bloodstream. In contrast, industrial paints and hair dyes displayed predominantly diamagnetic behavior, excluding significant iron oxide presence. The results demonstrate that everyday materials and combustion-derived residues may act as sources of ultrafine ferromagnetic particles with potential health implications. These findings highlight the importance of magnetic characterization as a complementary tool in environmental and biomedical studies aimed at assessing exposure to iron-rich particulate matter.
- Mapping the Pan-African inventory of Critical Raw Material deposits and processing capacitiesPublication . Fortes, Carla; de Oliveira, Daniel Pipa Soares; Guillaneau, Jean-Claude; Marques Prazeres, CátiaABSTRACT: The AfricaMaVal project (2022–2025) supported the European Union’s objective of securing responsible and sustainable access to Extended Critical Raw Materials (ECRM) through strengthened cooperation with African countries. This study presents the development of two harmonised pan-African inventories: an ECRM mineral deposit database and a database of existing ore processing and refining capacities. Using the Minerals4EU data model within an INSPIRE compliant framework, heterogeneous datasets were integrated and validated through commercial and consortium sources. The resulting inventories document more than 20.000 mineral occurrences and 219 processing facilities, classified as plants, smelters, refineries and concentrators. The analysis reveals a strong geographical concentration, with South Africa and the Democratic Republic of Congo hosting over half of all facilities, and processing activities largely centred on copper and cobalt. These findings highlight regional disparities and priority areas for investment. Overall, the inventories provide a robust knowledge base to support a resilient EU raw materials strategy and guide future EU–Africa partnerships.
- Opportunities and challenges in a world-class mining district, the Iberian Pyrite BeltPublication . Castelo Branco, José M.ABSTRACT: A summary is made on the exploration work carried out in the Iberian Pyrite Belt (IPB) and an attempt is made to describe the evolution of the exploration methods and strategies applied in the field which led to the discovery of the main deposits. Finally, a reference is made to the good potential for new discoveries in the IPB, giving clues about new exploration models to be pursued. Being undoubtedly a world-class metallogenic province, the IPB naturally deserves a special mention regarding the mining history and on the evolution of the exploration techniques, adjusted to the new paradigms, namely in the need to search at ever greater depths. The most recent cases of successful new discoveries in the IPB are described, largely resulting from the refining of geological, geophysical and geochemical prospecting methodologies, and clues that are expected to lead to the discovery of new concealed deposits are equated.