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Castro Verde, Portugal

Pinto A.,University of Lisbon | Relvas J.M.R.S.,University of Lisbon | Carvalho J.R.S.,University of Lisbon | Liu Y.,University of Toronto | And 3 more authors.
Comunicacoes Geologicas | Year: 2014

The increasing consumption of indium and selenium has significantly stimulated their extraction output, adding economic interest to critical metal sources that a few years ago were either unknown, or unconsidered. In addition to Cu (Sn and Ag as byproducts), recent surface drill programs looking for further development of the Neves Corvo mine have defined, by the end of 2013, 113 Mt of zinc resources @ 5.3% Zn, which turned the deposit into one of the world’s largest undeveloped zinc resources. Promising by-products can possibly include some high-tech metals such as In and Se. In Neves Corvo there is a general positive correlation between In and Cu at the deposit scale, which contrasts with most other In-bearing VHMS deposits, where In typically follows Zn. At Neves Corvo, indium grades vary within the range 20 to 1100 ppm (1.1 kg/ton), whereas selenium grade commonly ranges between 20 and 40 ppm, although in some lead-rich domains selenium grades can reach up to 8000 ppm Se (avg. 500 ppm). Despite the general copper-indium coupling in the deposit, there is an obvious interest in evaluating the potential of the zinc-rich ores in terms of high-tech metals contents as these elements are widely acknowledged as adding value to the zinc concentrates, thus being payed by most zinc smelters. In this study, we present the most recent available data on the metal distribution and mineralogy of indium and selenium in the massive zinc and lead-zinc ores of the Neves Corvo deposit. This deposit may represent in the future a promising target for high-tech metals, such as indium and selenium. © 2014, LNEG – Laboratório Nacional de Geologia e Energia IP.

Relvas J.M.R.S.,University of Lisbon | Pinto A.,University of Lisbon | Carvalho J.R.S.,University of Lisbon | Rosa C.J.P.,EDM Empresa de Desenvolvimento Mineiro | And 3 more authors.
Comunicacoes Geologicas | Year: 2014

In the Neves Corvo deposit there is overwhelming evidence for silicate-sulfide replacement processes being largely responsible for the efficiency of the ore-forming system and huge size of the deposit. Textural evidences at all scales, coupled with a well-constrained mass-balance geochemical analysis, indicate that extensive replacement in the lava-dominated volcanic rocks of the footwall sequence, and disseminated replacement mineralization in the volcaniclastic and/or sedimentary units were major mechanisms of ore formation in this deposit. Shallow sub-seafloor metal deposition prior to fluid discharge is likely to play a major role either in fossil, or in active massive sulfide mineralization. This premise should be envisaged as critical in evaluating the economic potential of present-day seafloor resources. © 2014, LNEG – Laboratório Nacional de Geologia e Energia IP.

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