Caracterizações petrográfica e química de horizontes calcissilicáticos e ocorrências de scheelita na região de Arapeí, leste do Estado de São Paulo

• Ano de defesa: 2022
• Autor(a) principal: Sousa, Luis Diego Moraes
• Orientador(a): Salomão, Marcelo dos Santos
• Banca de defesa: Nummer, Alexis Rosa, Geraldes, Mauro, Palermo, Nely
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade do Estado do Rio de Janeiro
• Programa de Pós-Graduação: Programa de Pós-Graduação em Geociências
• Departamento: Centro de Tecnologia e Ciências::Faculdade de Geologia
• País: Brasil
• Palavras-chave em Português: Tungstênio; Scheelita; Calcissilicática; MEV-EDS; Geoquímica
• Palavras-chave em Inglês: Tungsten; Scheelite; Calcissilicate; SEM-EDS; Geochemistry
• Área do conhecimento CNPq: CIENCIAS EXATAS E DA TERRA::GEOCIENCIAS::GEOLOGIA
• Link de acesso: http://www.bdtd.uerj.br/handle/1/19756

In the eastern portion of the State of São Paulo (SE Brazil), specifically in the region of the municipality of Arapeí, occurrences of the mineral scheelite associated with calcsilicate rocks from the Beleza Unit, belonging to the central segment of the Ribeira Belt, specifically, to the Klippe Paraíba do Sul, were studied In the Beleza Unity there are metric to centimetric lenses of calcsilicate rocks (banded and massive) and calcitic-dolomitic marble. Scheelite - calcium tungstanate (CaWO3) - is a mineral of important economic interest because it is rich in the element W (tungsten). Tungsten is a metallic chemical element belonging to the transition metals class, it is the metal with the highest melting point (3,422 °C), the lowest vapor pressure and the highest tensile strength, with a boiling point of 5,700 °C. Its physicochemical characteristics give the metal a wide applicability within the national and international market. Its applications range from making filaments of incandescent lamps and electrodes, cathodes and anti-cathodes of X-ray equipment to surgical precision blades and industrial components war and aerospace. The world's largest producer of W is China, which holds approximately 65% of the world's reserves. In Brazil, the main producing state of W is Rio Grande do Norte, where the largest historical production of scheelite occurred (region of Seridó), especially in the municipalities of Currais Novos, São Tome and Acari. In the Arapeí region, where the present work was carried out, according to Pereira and Avila (2008), the scheelite found in the Arapeí and Piquete areas is associated with interstratified calc-silicate rocks in sets represented by biotite gneiss and hornblende- biotite gneiss, quartzites and marbles. The samples of pan concentrate taken from the river beds, which cross the Beleza Unit, proved the occurrence of the mineral, with SEM-EDS results showing a very high W content, characteristic of the scheelite mineral. The low concentration of W in the geochemical analysis of calc-silicate rocks and the presence of scheelite in the pan concentrates indicate that the mineral is dispersed and in low concentration in the lenses of calc-silicate rocks present in the region. The studies of lithological units related to these strips can contribute to an expansion of mineral research in medium to high metamorphic grade terrains in the state of Rio de Janeiro, pointing to a new focus and potential in these, based on the strategic and economic importance of the W for the industry.