Zn-clay minerals in the Skorpion Zn nonsulfide deposit (Namibia): Identification and genetic clues revealed by HRTEM and AEM study

Balassone, Giuseppina; Nieto, Fernando; Arfè, Giuseppe; Boni, Maria; Mondillo, Nicola

doi:10.1016/j.clay.2017.09.034

Cited by 15 publications

(25 citation statements)

References 28 publications

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“…HAADF STEM enhances Z-scale contrast, enabling atomic-scale resolution with applicability to many minerals that are found within ore deposits, e.g., mixed-layer chalcogenide compounds of the tetradymite group [39], as shown in Figure 3. The atomic-scale resolution possible with contemporary state-of-the-art STEM instrumentation in HAADF STEM mode is particularly well-suited to visualise the structures of complex sulphosalts e.g., Pb-Bi-sulphosalts [23], Zn-bearing smectites [41,42], or disordered intergrowths among mixedlayer compounds, such as the REE-fluorocarbonates [43]. Atomic-scale HAADF STEM imaging is a more direct tool than high-resolution TEM since it provides a better control on the correlation between crystal structures and chemical variation.…”

Section: Haadf Stem Imaging and Stem-eds Mappingmentioning

confidence: 99%

Advances and Opportunities in Ore Mineralogy

et al. 2017

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Abstract:The study of ore minerals is rapidly transforming due to an explosion of new microand nano-analytical technologies. These advanced microbeam techniques can expose the physical and chemical character of ore minerals at ever-better spatial resolution and analytical precision. The insights that can be obtained from ten of today's most important, or emerging, techniques and methodologies are reviewed: laser-ablation inductively-coupled plasma mass spectrometry; focussed ion beam-scanning electron microscopy; high-angle annular dark field scanning transmission electron microscopy; electron back-scatter diffraction; synchrotron X-ray fluorescence mapping; automated mineral analysis (Quantitative Evaluation of Mineralogy via Scanning Electron Microscopy and Mineral Liberation Analysis); nanoscale secondary ion mass spectrometry; atom probe tomography; radioisotope geochronology using ore minerals; and, non-traditional stable isotopes. Many of these technical advances cut across conceptual boundaries between mineralogy and geochemistry and require an in-depth knowledge of the material that is being analysed. These technological advances are accompanied by changing approaches to ore mineralogy: the increased focus on trace element distributions; the challenges offered by nanoscale characterisation; and the recognition of the critical petrogenetic information in gangue minerals, and, thus the need to for a holistic approach to the characterization of mineral assemblages. Using original examples, with an emphasis on iron oxide-copper-gold deposits, we show how increased analytical capabilities, particularly imaging and chemical mapping at the nanoscale, offer the potential to resolve outstanding questions in ore mineralogy. Broad regional or deposit-scale genetic models can be validated or refuted by careful analysis at the smallest scales of observation. As the volume of information at different scales of observation expands, the level of complexity that is revealed will increase, in turn generating additional research questions. Topics that are likely to be a focus of breakthrough research over the coming decades include, understanding atomic-scale distributions of metals and the role of nanoparticles, as well how minerals adapt, at the lattice-scale, to changing physicochemical conditions. Most importantly, the complementary use of advanced microbeam techniques allows for information of different types and levels of quantification on the same materials to be correlated.

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Section: Haadf Stem Imaging and Stem-eds Mappingmentioning

confidence: 99%

Advances and Opportunities in Ore Mineralogy

et al. 2017

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“…The difference between 100% zinc dissolution efficiency and dissolution efficiencies obtained in NaOH and HCl solutions probably be caused by the presence of zinc, other than in smithsonite, in structures of minerals of ore sample having some resistance to dissolution both in alkaline and acid solutions, i.e. zinc containing dolomite, clay minerals, goethite and calcite, as also indicated in the related literature (Whittaker and Żabiński, 1981;Rosenberg and Champness, 1989;Borg et al, 2003;Boni et al, 2009a,b;Coppola et al, 2009;Mondillo et al, 2011;Boni et al, 2013;Mondillo et al, 2014;Santoro et al, 2014;Mondillo et al, 2015;Paradis et al, 2015;Choulet et al, 2016;Arfè et al, 2017;Balassone et al, 2017).…”

Section: Resultsmentioning

confidence: 70%

Dissolution Properties of a Dolomite Containing Zinc Ore in Sodium Hydroxide Solutions

Kumaş

Ehsani

Obut

2020

Bilimsel Madencilik Dergisi

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In this work, the dissolution properties of a dolomite containing zinc carbonate (smithsonite) ore sample having 24.22% ZnO were determined in sodium hydroxide solutions using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), thermal (TG/DTA) and chemical analyses methods. It was observed that the dissolution efficiency value of zinc continuously increased with the increase of sodium hydroxide concentration from 1 to 4 M and the highest zinc dissolution efficiency of 70.7% was reached after dissolution in 4 M NaOH solution at temperature of 298 K. The XRD, FT-IR, TG/DTA and chemical analyses of undissolved solids obtained after dissolution of ore sample in 4 M NaOH solution at 298 K revealed that the smithsonite phase in the sample completely dissolved whereas the main gangue mineral dolomite remained practically unaffected, showing the selectivity of sodium hydroxide solution considering zinc dissolution. Although the smithsonite phase in the sample totally dissolved, hundred percent zinc dissolution efficiency could not be reached, which may indicate the presence of zinc in the gangue components, i.e. dolomite, clay minerals etc., of the studied ore sample. ÖZBu çalışmada, dolomit içeren bir çinko karbonat (simitsonit) cevher numunesinin (%24,22 ZnO) sodyum hidroksit çözeltilerindeki çözünme özellikleri X-ışını kırınımı (XRD), Fourier dönüşümlü kızılötesi spektroskopisi (FT-IR), ısıl (TG/DTA) ve kimyasal analiz yöntemleri kullanılarak belirlenmiştir. Sodyum hidroksit derişiminin 1'den 4 M'ye artırılmasıyla çinko çözünme verimi değerinin sürekli olarak arttığı gözlenmiş ve %70,7'lik en yüksek çinko çözünme verimine 298 K sıcaklıktaki 4 M NaOH çözeltisinde yapılan çözme işlemi sonrasında ulaşılmıştır. Cevher numunesinin 298 K'deki 4 M NaOH çözeltisinde çözündürülmesi sonrasında elde edilen çözünmemiş katıların XRD, FT-IR, TG/DTA ve kimyasal analizleri, numune içindeki simitsonit fazının tamamen çözündüğü halde ana gang minerali dolomitin büyük ölçüde çözünmeden kaldığını ortaya çıkarmakta, bu durum da çinko çözünmesi dikkate alındığında sodyum hidroksit çözeltisinin seçiciliğini göstermektedir. Numunedeki simitsonit fazının tümünün çözünmesine rağmen yüzde yüz çinko çözünme verimine ulaşılamaması, çalışılan cevher numunesi içinde bulunan dolomit, kil mineralleri vb. gibi gang bileşenlerindeki muhtemel çinko varlığını işaret etmektedir.

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“…Textural observations would suggest that the original illite or I/S mixed layers were of detrital or sedimentary origin (e.g., I/S mixed layers show Reichweite values "R" > 1, which are commonly produced by diagenetic processes [55]. Looking at the existing literature [29,31], Zn incorporation in these phyllosilicates could be related either to the same hydrothermal processes that are responsible for the emplacement of sulfides [34,35], or to supergene alteration, which allowed for the formation of nonsulfide ores. In both cases, Zn incorporation into the I/S also produced an increase of the smectite (i.e., sauconite) component in the mixed layer.…”

Section: Discussionmentioning

confidence: 99%

“…In both cases, Zn incorporation into the I/S also produced an increase of the smectite (i.e., sauconite) component in the mixed layer. However, we cannot exclude that part of the detected sauconite that overgrows the I/S grains, instead of being incorporated into the mixed layers, using the I/S lamellae as a template on which smectite crystallizes directly from fluids, as already observed in other deposits [29,31].…”

Section: Discussionmentioning

confidence: 99%

Identification of Zn-Bearing Micas and Clays from the Cristal and Mina Grande Zinc Deposits (Bongará Province, Amazonas Region, Northern Peru)

et al. 2017

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Zn-bearing phyllosilicates are common minerals in nonsulfide Zn deposits, but they seldom represent the prevailing economic species. However, even though the presence of Zn-bearing clays is considered as a disadvantage in mineral processing, their characteristics can give crucial information on the genesis of the oxidized mineralization. This research has been carried out on the Mina Grande and Cristal Zn-sulfide/nonsulfide deposits, which occur in the Bongará district (Northern Peru). In both of the deposits, Zn-bearing micas and clays occur as an accessory to the ore minerals. The XRD analyses and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) investigations revealed that the Zn-bearing micas that are occurring in both deposits mostly consist of I/S mixed layers of detrital origin, which have been partly altered or overprinted by sauconite during the supergene alteration of sulfides. Sporadic hendricksite was also identified in the Cristal nonsulfide mineral assemblage, whereas at Mina Grande, the fraipontite-zaccagnaite (3R-polytype) association was detected. The identified zaccagnaite polytype suggests that both fraipontite and zaccagnaite are genetically related to weathering processes. The hendricksite detected at Cristal is a product of hydrothermal alteration, which is formed during the emplacement of sulfides. The complex nature of the identified phyllosilicates may be considered as evidence of the multiple processes (hydrothermal and supergene) that occurred in the Bongará district.

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Zn-clay minerals in the Skorpion Zn nonsulfide deposit (Namibia): Identification and genetic clues revealed by HRTEM and AEM study

Cited by 15 publications

References 28 publications

Advances and Opportunities in Ore Mineralogy

Advances and Opportunities in Ore Mineralogy

Dissolution Properties of a Dolomite Containing Zinc Ore in Sodium Hydroxide Solutions

Identification of Zn-Bearing Micas and Clays from the Cristal and Mina Grande Zinc Deposits (Bongará Province, Amazonas Region, Northern Peru)

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