Navegando por Assunto "Gemas (Mineralogia)"

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Acesso aberto (Open Access)
O estado da arte do setor de gemas e joias no município de Belém - Pará
(Universidade Federal do Pará, 2012-09-17) PINTO, Rosângela Gouvêa; MITSCHEIN, Thomas Adalbert; http://lattes.cnpq.br/7431424927108512
The purpose of this dissertation is to characterize the state of the art of the jeweler industry deployed in the State of Para, which is housed in the Area St. José Liberto, located in the city of Belém is administered by the Institute of Gems and Jewels of the State of Pará - IGAMA. The characterization is done through the analysis of agents that drive its development, considering the deployment of a government program started in 1998, focused on the verticalization of mineral industry, focusing on the prospect of installing a pole in the State of Pará jeweler this analysis are considered the economic, cultural, environmental and man himself as the subject of the installation process to a chain jeweler, in a state that does not have the tradition of great centers of jewelry production, concentrated in the Southeast, as in the states of São Paulo, Minas Gerais and Rio de Janeiro, which originates from a European production scenario, where the labor and craft originated throughout its history, with market development, migrated to the industrial mode of production without however, losing the characteristics of the jewel "handmade" in certain phases of the production process. The results of this research identified the main constraints, so that in fact this sector to consolidate and provide the State of Pará recognition of more genuinely a product of Para, where it uses raw materials, labor and cultural issues local allies the factors of competitiveness and quality for inclusion in the market. In taking the panorama of the sector, was used to search literature and documents in government programs for 1998 through 2011, institutional reports, periodicals and books. Concomitantly, the study of the methodology applied in the event of generation of new products in jewelry, through strategies for obtaining data as the research participant, photographic records and the application of qualitative and quantitative questionnaires.
Acesso aberto (Open Access)
Mineralogia e gemologia da opala laranja de Buriti dos Montes (Piauí, Brasil)
(Universidade Federal do Pará, 2002-02-28) GOMES, Érico Rodrigues; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302
Acesso aberto (Open Access)
Opalas gemológicas do Piauí: gênese revelada por microtermometria e minerais associados
(Universidade Federal do Pará, 2014-04-25) MARQUES, Gisele Tavares; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302
Opals from Pedro II and Buriti dos Montes, in the Piauí State, are the most important occurrences of this gemstone in Brazil, both in terms of volume and -gemological quality that is comparable to the famous Australian opals. However, informality in the extraction and marketing of these opals, as well as the lack of information about the genesis of these deposits do not permit prospecting for new deposits, and the establishment of a certificate of origin for Piauí opals, would allow their formal participation in the international gemological market. Some authors have been studied these opals, revealing strong evidences of their hydrothermal origin, but until now, no work discussed the physico-chemical characteristics of the fluids that would have originated these opals deposits. Thus, the main objective of this work was to understand the hydrothermal system responsible for the genesis of opals from Piauí, i.e., to characterize the fluids that originated the mineralization and show its relationship with the geological context of this region. Pedro II and Buriti dos Montes counties are located in the northeastern portion of the Piauí State, at approximately 230 km east of the capital Teresina. The opal occurrences are on the basis of the Parnaíba Basin, constituting veins and veinlets in the sandstones of the Serra Grande (Buriti dos Montes) and Canindé (Pedro II) groups, which are cut by diabase sills and dikes of the Sardinha Formation. They also occur in cementing breccias and as colluvial and paleochannel deposits. Associated to opals, locally there are veins of quartz, chalcedony, barite and hematite (or goethite). In general, opals from Pedro II present play-of-color, are mostly white or bluish with a milky appearance, semitranslucent to opaque, and have solid inclusions little bit apparent. In contrast, orange opals from Buriti dos Montes do not show play-of-color, their color ranges from light yellow to brownish red, they are semitransparent to translucent, and contain a large variety of solid inclusions. The obtained data reveal that the opals from Pedro II are typically of amorphous type (opal-A), while the opals from Buriti dos Montes range between amorphous and cristobalite-tridymite (opal-CT). In the precious opals, the typical play-of-color is caused by the regular arrangement of the silica spheres that constitute them. The absence of opaline cement among the spheres reinforces the beauty of this effect. On the other hand, the orange opals do not show play-of-color, but they have greater transparency due to the small size of the spheres. The solid inclusions also produce beautiful effects in the studied opals, mainly in the orange variety that is more transparent. Besides this, the solid inclusions set reveals intrinsic characteristics to hydrothermal processes that originated the studied opals. Botryoidal, dendritic and nodular aggregates are examples of inclusions formed by fragments of the host sandstones, which were carried by the hydrothermal fluids that generated the opals. In the opals from Buriti dos Montes, the red, orange and yellow hues are produced by the partial dissolution of the Fe oxy-hydroxides inclusions. Similarly, the green color in the precious opals is related to Co-pentlandite microcrystals included in them. The set of minerals associated to opals leads to a mineralogical-geochemical signature marked by high contents of Fe and Al in opals with hematite/goethite and kaolinite inclusions, such as the considerable increase in the rare earth elements contents, in the opals that have kaolinite and apatite inclusions. Among the trace elements, Ba is the most abundant, and it probably was incorporated to hydrothermal fluid, considering that veins of barite are frequently found in this region of Parnaíba Basin. Some features such as flow structures in the opals, corrosion and partial dissolution in the hyaline quartz crystals and mineralogical inclusions, hydrothermal quartz veinlets that overgrew to detrital grains, and zoning in the quartz crystals, confirm that these opals have hydrothermal origin. The Gondwana rupture would have caused a wide fissural basic magmatism, which was the responsible for the heat supply that generated the first convective cells of hot fluids. The water contained in the sandstones certainly filled the system and enriched in silica through partial or total dissolution of the quartz grains of sandstones. This hydrothermal fluid was subsequently hosted and cooled in the fracture systems, precipitating the opal and associated minerals.
Acesso aberto (Open Access)
Orange opals from Buriti dos Montes, Piauí: solid inclusions as genetic guides
(2015-03) MARQUES, Gisele Tavares; COSTA, Marcondes Lima da; GOMES, Érico Rodrigues
Orange opals from Buriti dos Montes (Piauí, northeastern Brazil) have gemological properties that favor their use as jewelry; these characteristics include their colors, transparency, relatively high stability and hardness. The exotic content of solid inclusions provides greater beauty to the opals of this region. These opals originated from hydrothermal processes and are found mainly as veinlets and veins in the sandstones of the Serra Grande Group, sectioned by diabase dikes and sills of the Sardinha Formation. Solid inclusions, such as bubbles, botryoidal aggregates, dendrites, and nodules, among others, consist mainly of kaolinite, hematite/goethite and quartz and influence the chemical composition of opals. Intense zoning of quartz crystals and high values of Ba and Fe suggest that opal deposits were formed in a hydrothermal environment. Diabase dykes could have been responsible for heating the hydrothermal fluids. Sandstones, rich in aqueous solutions, also contributed to the available silica for the saturation of these solutions, and fractures enabled the migration and entrapment of hydrothermal fluids, resulting in the mineralized veins.
Acesso aberto (Open Access)
Políticas públicas e as pequenas empresas no cenário da mineração: o setor de gemas e jóias de Belém
(Universidade Federal do Pará, 2015-04-30) CHAVES, Débora Almeida; MATHIS, Armin; http://lattes.cnpq.br/8365078023155571
This study has as its object the state intervention through public policies, for one of the sectors of mineral Pará state economy. Taking as empiric cutting gems and jewelry sector that develops in Bethlehem, because of present with the best organization and structure for the research. Thus was formulated as a problem: How State intervention, through their public policies, impact on gems and jewelry Bethlehem and how this rebate in favor of endogenous regional development sector? Since it would fall to this sector contribute to changes as the scenario of the state's mineral economy through vertical integration of production of precious metals and gems found in Pará underground. As a general objective was to analyze how and how public policies (developed and implemented by the state) approach to development of the Gems and Jewellery sector of Belém. To reach that goal this methodology based from a systemic approach, as this approach provides operationalize the research problem situations and forms of interventions to improve such situations. Also guided on the methodology from the perspective of Social Systems Theory of Niklas Luhmann, emphasizing a) autorrefenciados / autopoietic systems; b) observer 2nd order. As for the method it has been qualitative, with research strategy adopted was a case study. (Intrinsic case study), also employed to search and Document Analysis. And as data collection technique: semi structured interviews and questionnaire (with contingent questions). The results show that even the state of Pará featuring a sectoral public policy for the promotion of development of the gems and jewelry sector, such still can not realize the seminal idea of verticalization of mineral production and that public policy is presented as a vicious cycle not being able also to generate effectiveness of its actions