Advances and Opportunities in Ore Mineralogy

Cook, Nigel J.; Ciobanu, Cristiana L.; Ehrig, Kathy; Slattery, Ashley; Verdugo-Ihl, Max R.; Courtney‐Davies, Liam; Gao, Wenyuan

doi:10.3390/min7120233

Cited by 38 publications

(29 citation statements)

References 171 publications

(194 reference statements)

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“…Irrespectively of specific chemistry, in all layered chalcogenides, the building modules (anion-anion bonds) are separated from one another by van der Waals gaps [1,2,8,9] and thus cannot be reconciled with the sensu stricto definition of Bi-Pb-sulphosalts [25]. The five-atom atomic arrangement separated by gaps was confirmed by HAADF STEM imaging of natural tellurobismuthite [26] and its synthetic analogue [27][28][29][30]. High-resolution HAADF STEM images of such compounds has allowed further insight into the role played by atomic interfaces, (0001) basal twin boundaries, dislocations and Bi 3 Te 4 defects in Bi 2 Te 3 in controlling thermoelectric properties.…”

Section: Introductionmentioning

confidence: 99%

Polytypism and Polysomatism in Mixed-Layer Chalcogenides: Characterization of PbBi4Te4S3 and Inferences for Ordered Phases in the Aleksite Series

et al. 2019

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Bi-Pb-chalcogenides of the aleksite series represent homologous mixed-layer compounds derived from tetradymite (Bi2Te2S). Considering tetradymite as composed of five-atom (Bi2Te2S) layers, the named minerals of the aleksite homologous series, aleksite (PbBi2Te2S2) and saddlebackite, (Pb2Bi2Te2S3) have been considered as phases formed by regular stacking of longer seven- and nine-atom layers. High-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) imaging of thinned foils prepared in-situ on domains deemed homogeneous from electron probe microanalysis, STEM energy-dispersive X-ray spectrometry (EDS) element mapping and fast Fourier transforms (FFTs) from the images offer new insights into these structures. The hitherto-unnamed phase, PbBi4Te4S3, previously interpreted as regular intergrowths of five- and seven-atom layers, is characterized in terms of regular repeats of five- and seven-atom layers over distances of at least 350 nm, defining the (57), or 24H polytype. Imaging of other domains in the same lamella with identical composition at the electron microprobe scale reveals the presence of two additional polytypes: (5559), or 48H; and (557.559) or 72H. Unit cell dimensions for all three polytypes of PbBi4Te4S3 can be both measured and predicted from the HAADF STEM imaging and FFTs. STEM EDS mapping of each polytype confirm the internal structure of each layer. Lead and S occur within the centre of the layers, i.e., Te–Bi–S–Pb–S–Bi–Te in the seven-atom layer, Te–Bi–S–Pb–S–Pb–S–Bi–Te in the nine-atom layer, and so on. Polytypism is an intrinsic feature of the aleksite series, with each named mineral or unnamed phase, except the simple five-atom layer, defined by several alternative stacking sequences of different length, readily explaining the differing c values given in previous work. Homology is defined in terms of layer width and the stacking arrangement of those layers. Coherent structures of the same composition need not only be built of layers of adjacent size (i.e., five- and seven-atom layers) but, as exemplified by the (5559) polytype, may also contain non-adjacent layers, a finding not anticipated in previous work. New polysomes remain to be discovered in nature and each potentially exists as multiple polytypes. The present study further emphasizes the utility of HAADF STEM imaging and atomic-scale STEM EDS element mapping as an optimal tool for tracking stacking sequences and characterising structures in mixed-layer compounds.

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Section: Introductionmentioning

confidence: 99%

Polytypism and Polysomatism in Mixed-Layer Chalcogenides: Characterization of PbBi4Te4S3 and Inferences for Ordered Phases in the Aleksite Series

et al. 2019

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“…The main advantage is the determination of a large number of particles that are important for statistical results and reduction of human error [25]. However, the correct interpretation of automated mineralogy data requires a mineralogical understanding of the material [26], and must usually be used in conjunction with other mineralogical techniques, e.g., this technique does not distinguish between polymorph minerals. Another problem is the difficulty in obtaining a representative sample to analyze [27].…”

Section: Introductionmentioning

confidence: 99%

Quantitative Mineralogical Comparison between HPGR and Ball Mill Products of a Sn-Ta Ore

et al. 2018

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Abstract:The mineralogy and liberation characteristics of the comminuted Penouta leucogranite host of the Sn-Ta ore were determined. Grinding developed by a combination of high-pressure grinding rolls (HPGR) followed by a ball mill (BM) was compared with a single ball mill process. The mineral characteristics of the grinding products were analyzed using a Tescan Integrated Mineralogical Analyzer (TIMA-X) and X-ray powder diffraction (XRD). The ore contains 103 ppm of Ta and is mainly composed of quartz, albite, microcline, muscovite, and kaolinite. Nb, Ta-rich minerals are columbite-(Mn) and tantalite-(Mn), as well as minor microlite and wodginite. The liberation in the product is high in the size fraction of less than 250 µm (51-52 wt % for columbite-group minerals (CGM) and 74-80 wt % for cassiterite) and reduced in larger particles (8.8-17 wt % for CGM and 28-37 wt % for cassiterite). The recovery in the −250 µm fraction was high, while in the larger fraction it is limited, remaining up to 80 ppm in some tailings. The combined use of HPGR and a BM reduces the particle size distribution of the product and, thus, increases the liberation of the ores. Smaller fractions can be treated directly using gravity methods; however, particles of a size greater than +250 µm should be ground more.

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“…Hematite is the most abundant gangue mineral in the deposit. Within this hematite, uranium and lead isotopes, both in solid solution and as nanoparticle inclusions [154] are in apparent secular equilibrium, indicating a closed system and providing a basis for U-Pb geochronology using hematite [152,155,156].…”

Section: Re-incorporation Of Radionuclides Into Parent Mineralsmentioning

confidence: 88%

210Pb and 210Po in Geological and Related Anthropogenic Materials: Implications for Their Mineralogical Distribution in Base Metal Ores

et al. 2018

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Abstract:The distributions of 210 Pb and 210 Po, short half-life products of 238 U decay, in geological and related anthropogenic materials are reviewed, with emphasis on their geochemical behaviours and likely mineral hosts. Concentrations of natural 210 Pb and 210 Po in igneous and related hydrothermal environments are governed by release from crustal reservoirs. 210 Po may undergo volatilisation, inducing disequilibrium in magmatic systems. In sedimentary environments (marine, lacustrine, deltaic and fluvial), as in soils, concentrations of 210 Pb and 210 Po are commonly derived from a combination of natural and anthropogenic sources. Enhanced concentrations of both radionuclides are reported in media from a variety of industrial operations, including uranium mill tailings, waste from phosphoric acid production, oil and gas exploitation and energy production from coals, as well as in residues from the mining and smelting of uranium-bearing copper ores. Although the mineral hosts of the two radionuclides in most solid media are readily defined as those containing parent 238 U and 226 Ra, their distributions in some hydrothermal U-bearing ores and the products of processing those ores are much less well constrained. Much of the present understanding of these radionuclides is based on indirect data rather than direct observation and potential hosts are likely to be diverse, with deportments depending on the local geochemical environment. Some predictions can nevertheless be made based on the geochemical properties of 210 Pb and 210 Po and those of the intermediate products of 238 U decay, including isotopes of Ra and Rn. Alongside all U-bearing minerals, the potential hosts of 210 Pb and 210 Po may include Pb-bearing chalcogenides such as galena, as well as a range of sulphates, carbonates, and Fe-oxides. 210 Pb and 210 Po are also likely to occur as nanoparticles adsorbed onto the surface of other minerals, such as clays, Fe-(hydr)oxides and possibly also carbonates. In rocks, unsupported 210 Pb-and/or 210 Po-bearing nanoparticles may also be present within micro-fractures in minerals and at the interfaces of mineral grains. Despite forming under very limited and special conditions, the local-scale isotopic disequilibrium they infer is highly relevant for understanding their distributions in mineralized rocks and processing products.

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Advances and Opportunities in Ore Mineralogy

Cited by 38 publications

References 171 publications

Polytypism and Polysomatism in Mixed-Layer Chalcogenides: Characterization of PbBi4Te4S3 and Inferences for Ordered Phases in the Aleksite Series

Polytypism and Polysomatism in Mixed-Layer Chalcogenides: Characterization of PbBi4Te4S3 and Inferences for Ordered Phases in the Aleksite Series

Quantitative Mineralogical Comparison between HPGR and Ball Mill Products of a Sn-Ta Ore

210Pb and 210Po in Geological and Related Anthropogenic Materials: Implications for Their Mineralogical Distribution in Base Metal Ores

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