Use of QEMSCAN® for the characterization of Ni-rich and Ni-poor goethite in laterite ores

Andersen, Jens C.Ø.; Rollinson, Gavyn; Snook, Ben; Herrington, Richard; Fairhurst, R.

doi:10.1016/j.mineng.2009.03.012

Cited by 63 publications

(28 citation statements)

References 5 publications

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“…Very fine grained material such as mixed 273 clays (less than 5 microns) may also be difficult to separate chemically due to the beam excitation 274 volume effects and only elements that are greater than approx. 3% in 275 concentration at each analysis point may be detected(Andersen et al, 2009). Total percentages for each 276 mineral group reported here, have been corrected to include soil organic carbon (SOC) as measured 277 during the Tellus survey, as SOC is not quantified by QEMSCAN ® analysis.…”

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confidence: 99%

Mineralogical characterisation to improve understanding of oral bioaccessibility of Cr and Ni in basaltic soils in Northern Ireland

Cox

Rollinson

McKinley

2017

Journal of Geochemical Exploration

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18Underlying bedrock is often the source of elevated levels of potentially toxic elements (PTEs) (including 19 Ni and Cr) in soils, which can be at concentrations exceeding regulatory guidelines for the protection of 20 human health. However geogenic contaminants are often not significantly bioavailable to humans as 21 they are bound tightly within the soil matrix. Therefore oral bioaccessibility testing can be used to 22 Highlights 42  Ni and Cr analysis of Basaltic soils overlying Antrim Basalts of Northern Ireland 43  Combined chemical and mineralogical data for improved understanding 44  High resolution analysis of samples, consistent across analytical methods 45  Bioaccessible Ni in precursor clay minerals, secondary Fe-oxides and carbonates 46  Low Cr bioaccessibility as Cr predominantly in chrome spinel and primary Fe-oxides 47 mineralogy of soils overlying the Antrim Basalts is characterised using both quantitative XRD and 127 QEMSCAN ® analyses combined with detailed geochemical data; 2) detailed elemental and mineralogical 128 mapping are compared to determine which minerals host total Ni and Cr; and 3) this information is 129 related to results of previous bioaccessibility testing (Barsby et al., 2012) and non-specific sequential 130 extractions (Cox et al., 2013) to elucidate how the oral bioaccessibility of both Ni and Cr is affected by 131 soil composition. 132 133

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confidence: 99%

Mineralogical characterisation to improve understanding of oral bioaccessibility of Cr and Ni in basaltic soils in Northern Ireland

Cox

Rollinson

McKinley

2017

Journal of Geochemical Exploration

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“…A scan was performed on a carbon-coated (25 nm thickness) 30 × 20 mm polished block of the sulphide-bearing black phase. Standard measurement settings were applied; a 25 kV, 5 nA beam with a width of approximately 600 nm, a working distance of approximately 22 mm and a 1000 count X-ray spectra (for more details see [40,41]). The whole sample area was analysed at a pixel resolution, i.e., a beam step size of 10 µm (46× magnification with field size of 1500 µm), and a smaller selective area was also measured at a pixel resolution, i.e., beam step size of 1 µm (238× magnification with field size of 300 µm).…”

Section: Methodsmentioning

confidence: 99%

Characterisation of Mineralised Material from the Loki’s Castle Hydrothermal Vent on the Mohn’s Ridge

et al. 2018

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Loki's Castle on the Arctic Mid-Ocean Ridge (AMOR) is an area of possible seafloor massive sulphide (SMS)-style mineralisation under Norwegian jurisdiction, which, due to mounting social pressure, may be a strategic future source of base and precious metals. The purpose of this study is to characterise mineralised material from a hydrothermal vent system on the AMOR in detail for the first time, and to discuss the suitability of methods used; reflected light microscopy, X-ray diffraction (XRD), whole rock geochemistry, electron probe micro-analysis (EPMA), and QEMSCAN. The primary sulphide phases, identifiable by microscopy, are pyrite and marcasite with minor pyrrhotite and galena, but multiple samples from the Loki's Castle contain economically interesting quantities of copper (hosted in isocubanite and chalcopyrite) and zinc (hosted in sphalerite), as well as silver and gold. This reinforces the notion that slow spreading ridges may host significant base metal deposits. Micro-textures (chalcopyrite inclusions and exsolutions in sphalerite and isocubanite respectively) are typically undefinable by QEMSCAN, and require quantitative measurement by EPMA. QEMSCAN can be used to efficiently generate average grain size and mineral association data, as well as composition data, and is likely to be a powerful tool in assessing the effectiveness of SMS mineral processing.

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“…QEMSCAN ® analyses were carried out at the conventional 1000 total X-ray counts per spectrum acquired, with an analytical time of ~3 h per sample. This analytical setting has suffi cient precision to discriminate mineral phases containing element abundances >~3 wt% (Andersen et al, 2009). The analyses were done using an accelerating voltage of 25 kV and a current of 5 nA.…”

Section: Methodsmentioning

confidence: 99%

A cold supergene zinc deposit in Alaska: The Reef Ridge case

Santoro

Boni

Mondillo

et al. 2015

Geological Society of America Bulletin

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The Reef Ridge deposit is a typical supergene "nonsulfi de" zinc mineralization, located in the Yukon-Koyukuk region of west-central Alaska (USA). It is hosted in sedimentary rocks of the Farewell terrane, a continental fragment sandwiched between the Siberian and Laurentian cratons during the early Paleozoic. The mineralization occurs in Lower-Middle Devonian shallowwater dolomite of a Paleozoic carbonate platform succession belonging to the Nixon Fork tectonic unit. The mineralization consists of oxidized minerals associated with minor remaining sulfi des (pyrite/marcasite and sphalerite). In the oxidation zone, smithsonite is the predominant mineral, mixed with Fe-(hydr)oxides (goethite and hematite).A complete petrographic and mineralogical study was performed. Samples were analyzed by X-ray diffraction, inductively coupled plasma-mass spectrometry and emission spectrometry, energy dispersive scanning electron microscopy, and QEMSCAN ® (quantitative evaluation of minerals by scanning electron microscopy). The most abundant mineral in the nonsulfi de ore is smithsonite. Similar to other nonsulfi de Zn deposits worldwide, the fi rst generation of smithsonite has replaced both primary sphalerite and the host carbonates. A second smithsonite generation precipitated as cement in vugs, cavities, and fractures. Minor zinc amounts also occur in the Fe-(hydr) oxides , and zinc traces have been identifi ed in clay minerals.The carbon and oxygen isotope values of smithsonite at Reef Ridge vary from -0.7 to 2.1‰ relative to Vienna Peedee belemnite (VPDB) and 19.1‰ to 21.9‰ relative to Vienna standard mean ocean water (VSMOW ). The δ 13 C values are similar to those of the host rock, suggesting that the predominant carbon source for smithsonite was the host carbonates, with only a limited contribution from organic carbon. The oxygen isotope ratios of Reef Ridge smithsonite are more depleted in 18 O compared to supergene nonsulfi des from other parts of the world formed under warm-humid, temperate, or semiarid climates. The oxygen isotope fractionation between water and smithsonite, which relates the δ 18 O value of the mineralizing solution, the formation temperature of smithsonite, and its δ 18 O composition, indicates that the δ 18 O composition of Reef Ridge smithsonite is related to very low formation temperatures (~10 °C), and strong depletion in 18 O of the precipitating waters.The δ 18 O smithsonite composition, the strong 18 O depletion, and the relationship of the formation of the Reef Ridge nonsulfi de deposit with the development of the Sleetmute upland surface (which started in the Late Tertiary and continues to the present) indicate that the formation of the Reef Ridge nonsulfi de deposit is probably related to cold/humid weathering episodes during a period comprised between Late Tertiary and Holocene.The "traditional" interpretation on the genesis of Zn nonsulfi de deposits in warmhumid, temperate, or semiarid conditions should be questioned where other climate zones are indicated.

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Use of QEMSCAN® for the characterization of Ni-rich and Ni-poor goethite in laterite ores

Cited by 63 publications

References 5 publications

Mineralogical characterisation to improve understanding of oral bioaccessibility of Cr and Ni in basaltic soils in Northern Ireland

Mineralogical characterisation to improve understanding of oral bioaccessibility of Cr and Ni in basaltic soils in Northern Ireland

Characterisation of Mineralised Material from the Loki’s Castle Hydrothermal Vent on the Mohn’s Ridge

A cold supergene zinc deposit in Alaska: The Reef Ridge case

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