sidérite et pyrite

Removal of dissolved selenium by siderite, pyrite, …

The rate of Se (IV) removal was pyrite > siderite > waste rock > sphalerite. The waste rock sample removed Se (IV) from solution in two stages: up to ~40% of the …

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Limonite

Several large and fairly rare Pyritohedral Limonite pseudomorphs after pyrite, a form well noted for this particular locality, and a highly prized find over the more commonly occuring cubic variety. Specimens from the Fruitville Pike Limonite Locality, just North of Lancaster, Lancaster Co., Pennsylvania (Dana locality). Acquired from the Jay ...

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Pyrite and siderite formation in brackish and …

Pyrite and siderite formation in brackish and freshwater swamp sediments Dieke Postma American Journal of Science Oct 1982, 282 (8) 1151-1183; DOI: 10.2475/ajs.282.8.1151

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Sphaerosiderites as sensitive recorders of …

Calcite and siderite have also been found together in ancient wetland deposits (Kantorowicz, 1985; Ufnar et al., 2004b; Weibel et al., 2016), and may reflect …

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Selenite reduction by mackinawite, magnetite and siderite…

Suboxic soils and sediments often contain the Fe(II)-bearing minerals mackinawite (FeS), siderite (FeCO3) or magnetite (FesO4), which should be able to reduce aqueous selenite, thereby forming solids of low solubility. While the reduction of selenate or selenite to Se(O) by green rust, pyrite and by …

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Ankerite

Ankerite cement occurs in 75% of the samples, with an average of 2.61%. Ferrocalcite cement is present in 21% of the samples, ranging from 0.2% to 15%. Both the ankerite (Fig. 12.7 A) and ferrocalcite cement (Fig. 12.7 C) occur predominately in filling pores.Since the Fe 2 + content is a proxy for burial cementation, carbonate cement with a significant …

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The microbially driven formation of siderite in salt marsh …

Nucleation of siderite during sedimentary diagenesis has been suggested to be a key pathway for formation of siderite in both modern (Vuillemin et al., 2019; Wittkopp, Teranes, Lubenow, ... The lack of pyrite and the presence of disseminated siderite in the incubated sediment suggest the heterogeneity of localized geochemistry within the ...

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Grain boundary widening controls siderite (FeCO3) …

Additionally, the molar volume change between dolomite (V Dol, 1CO3 = 32.17 cm 3 /mol, Robie et al. 15; V Ank, 1CO3, est = 32.86 cm 3 /mol, Anovitz and Essene 14) and siderite (V = 29.378 cm 3 ...

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Application of pyrite trace element chemistry to

The pyrite Se-Co-Sb-Ni contents are redox sensitive, and can be used as effective redox indicators (Maslennikov et al., 2009; Large et al., 2017, 2019; Feng et al., 2020). The increase of oxygen fugacity (ƒO2) would also increase the pyrite Se-Sb contents, but the effect is opposite on Co (Large et al., 2017, 2019; Mukherjee and …

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Electrochemical removal of pyrite scale using green formulations …

Previous studies have shown that Fe 3+ and dissolved oxygen are the essential oxidants involved in pyrite dissolution process 15,16,17; Li et al. 15,18 proposed the mechanism shown in Eqs. ( 2 ...

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Pyrite and siderite oxidation in swamp sediments

Pyrite oxidation leads to extreme soil acidification, with pH dropping to about 2, the release of large amounts of weathering products to the pore water, and the …

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Removal of dissolved selenium by siderite, pyrite, …

The sources of leachable Se in the coal waste rock dumps in the Elk Valley are the trace amounts of Se (-I) and Se (-II) incorporated into the primary sulfide minerals …

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An experimental study of the morphological evolution of pyrite …

1. Introduction. Pyrite is widely presented in hydrothermal gold deposits and is closely related to the time and space of gold mineralization (Müller and Groves, 1995; Christie and Brathwaite, 2003; Pirajno, 2009).Pyrite is a typical gold carrier in many hydrothermal gold deposits (Deditius et al., 2014; Yang et al., 2016; Vaughan and …

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Evidence from massive siderite beds for a CO

The absence of siderite in the pre-2.2-Gyr soils that were investigated by Rye et al. 1 and in many younger palaeosols was not because the atmospheric p CO 2 was <10-1.4 atm as they suggested, but ...

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Modes of occurrence of elements in coal: A critical evaluation

Coal, containing all the elements that are present in nature and more than 200 minerals, has a complex chemical structure, making it one of the most c…

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Frontiers | Genetic Mechanism and Environment …

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PNAS

The rise of oxygen and siderite oxidation during the …

WebA key remaining question is the mechanism by which the carbon produced by siderite and pyrite oxidation was directed to organic productivity. Increased carbon …

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THERMAL DECOMPOSITION OF SIDERITE–PYRITE …

conditions under which pyrite crystals trapped in the Opx (and glass) matrix experience in ALH84001, i.e., S vapor pressure builds up in the Opx matrix around the pyrite crystal and prevents thermal decomposition to pyrrhotite. Starting materials of siderite + pyrite in the open system yielded magnetite and pyrrhotite. The grains of

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Sidérite

Sidérite cristaux bruts avec quartz et chalcopyrite. Localité : St Pierre de Mésage, Isère, France. Dimension : 6.7 x 4.6 x 3 cm. 40,00 EUR. En Stock. Détails Acheter.

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Pyrite and siderite oxidation in swamp sediments

First published: March 1983 https://doi/10.1111/j.1365-2389.1983.tb00821.x Citations: 42 PDF Tools Share Summary Differences in the processes of pyrite and siderite …

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siderite et pyrite

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Pyrite formation from FeS and H

Using inorganic experimental systems, abiotic pyrite formation has been observed at temperatures of 25 °C to 125 °C (e.g., refs. 1 and 3).However, already, trace amounts of organic compounds containing aldehyde groups were reported to inhibit pyrite formation in such experiments (1, 4).Absence of stringent control for such compounds …

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Minerals | Free Full-Text | Genesis of Pyrite Concretions: Constraints

The occurrence of pyrite concretions in the Permian Longtan Formation sheds light on the paragenesis, formation conditions and regional paleoenvironment. We analyzed the mineral and geochemical characteristics of pyrite concretions using scanning electron microscopy-energy dispersive spectrometer (SEM-EDS), X-ray diffraction (XRD) …

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Siderite

Riverine sediments from the deepest past contain minerals (e.g., uraninite, pyrite, and siderite) that decompose rapidly under oxic conditions whereas such minerals are absent from more recent sediments (Kirkham and Roscoe, 1993; Ramdohr, 1958; Rasmussen and Buick, 1999; Robb et al., 1992).

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US4334882A

Thus, when pyrite and siderite are present in water and hydrocarbon bearing zones a combination of density and resistivity logs cannot accurately identify water/oil content. SUMMARY OF THE INVENTION The present invention discloses a method for the determination of pyrite and siderite content of core material to permit correction of …

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File : Sidérite, quartz, pyrite et pyrrhotite (Mexique).jpg

From Wikimedia Commons, the free media repository. Jump to navigation Jump to search. File; File history; File usage on Commons; Metadata

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(PDF) Selenium in pyrite ores

Selenium is con- centrated in the main sulfides, mainly in pyrite (73 g/t), chalcopyrite 49 g/t, pyrrhotite 48 g/t; in sphalerite usually <10 g/t. High Se content (up to 1–3 wt.%) occurs in the ...

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Figure 16. Pyrite and siderite coexisted in SGT1-11, SEM...

Syngenetic siderite, although not often, may co-exist with syngenetic pyrite in coal (e.g., Smyth, 1966;Kortenski, 1992;Ward, 2002; Zheng et al., 2017b). The co-existing pyrite and siderite in ...

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Estimated and measured iron content of siderite, pyrite, and …

In addition, the results could be biased by Iron-bearing minerals such as pyrite and siderite in the shale (Keating and Knight, 2010; Jin et al., 2021). The MDS method provides nanoscale ...

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The rise of oxygen and siderite oxidation during the Lomagundi Event

A key remaining question is the mechanism by which the carbon produced by siderite and pyrite oxidation was directed to organic productivity. Increased carbon input is a necessary, ... KO Konhauser, et al., Aerobic bacterial pyrite oxidation and acid rock drainage during the Great Oxidation Event. Nature 478, 369–373 (2011). Crossref.

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Removal of dissolved selenium by siderite, pyrite, and …

The sample collection procedure is presented in Hendry et al. (2015) whereas the mineralogy of the sample (number 30385a) is presented in Deen et al. (2018). The siderite content of the waste rock sample (by weight) was determined to be 1% using X-ray Diffraction (XRD) (Deen et al., 2018) and the pyrite and sphalerite contents were …

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