Structural relationship between pyrite and marcasite

Dódony, István; Pósfai, Mihály; Buseck, Peter R.

doi:10.2138/am-1996-1-215

Cited by 58 publications

(49 citation statements)

References 12 publications

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“…Abundant stacking faults from marcasite lamellae have been observed in pyrite grains in other studies, but these faults do not appear to be directly correlated with As substitution (DoÂ dony et al, 1996;PoÂ sfai and Buseck, 1997). Although the HR-TEM images of Clio-2 pyrite appear perfectly ordered and indicate As solid solution in pyrite, the presence of weak forbidden re¯ections was observed in selected area electron diffraction (SAED) patterns (arrows on right inset in Fig.…”

Section: High-resolution Transmission Electron Microsopymentioning

confidence: 87%

“…Mineral identi®cation of weathering product samples was conducted by X-ray diraction at Stanford University (see footnote c of Table 5). Imaging by high-resolution transmission electron microscopy (HR-TEM) was conducted at Arizona State University using techniques described by DoÂ dony et al (1996).…”

Section: Bulk Sample Characterizationmentioning

confidence: 99%

“…Defects associated with layers of an``arsenopyrite-like'' structure might produce faults such as those observed on {001} planes of arsenian pyrite by Fleet et al (1989). DoÂ dony et al (1996) also observed planar defect faults, but found them oriented perpendicular to one of the [001] axes in individual crystals. The TEM results do not appear to support the monolayer cluster model since defect faults are not observed, implying larger clusters with lower average As content.…”

Section: Arsenian Pyrite In Source Rocksmentioning

confidence: 99%

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Arsenic speciation in pyrite and secondary weathering phases, Mother Lode Gold District, Tuolumne County, California

Savage

Tingle

O’Day

et al. 2000

Applied Geochemistry

381

126

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Arsenian pyrite, formed during Cretaceous gold mineralization, is the primary source of As along the Melones fault zone in the southern Mother Lode Gold District of California. Mine tailings and associated weathering products from partially submerged inactive gold mines at Don Pedro Reservoir, on the Tuolumne River, contain H20±1300 ppm As. The highest concentrations are in weathering crusts from the Clio mine and nearby outcrops which contain goethite or jarosite. As is concentrated up to 2150 ppm in the ®ne-grained (<63 mm) fraction of these Fe-rich weathering products.Individual pyrite grains in albite-chlorite schists of the Clio mine tailings contain an average of 1.2 wt.% As. Pyrite grains are coarsely zoned, with local As concentrations ranging from H0 to 5 wt.%. Electron microprobe, transmission electron microscope, and extended X-ray absorption ®ne-structure spectroscopy (EXAFS) analyses indicate that As substitutes for S in pyrite and is not present as inclusions of arsenopyrite or other As-bearing phases. Comparison with simulated EXAFS spectra demonstrates that As atoms are locally clustered in the pyrite lattice and that the unit cell of arsenian pyrite is expanded by H2.6% relative to pure pyrite. During weathering, clustered substitution of As into pyrite may be responsible for accelerating oxidation, hydrolysis, and dissolution of arsenian pyrite relative to pure pyrite in weathered tailings. Arsenic K-edge EXAFS analysis of the ®ne-grained Ferich weathering products are consistent with corner-sharing between As(V) tetrahedra and Fe(III)-octahedra. Determinations of nearest-neighbor distances and atomic identities, generated from least-squares ®tting algorithms to spectral data, indicate that arsenate tetrahedra are sorbed on goethite mineral surfaces but substitute for SO 4 in jarosite. Erosional transport of As-bearing goethite and jarosite to Don Pedro Reservoir increases the potential for As mobility and bioavailability by desorption or dissolution. Both the substrate minerals and dissolved As species are expected to respond to seasonal changes in lake chemistry caused by thermal strati®cation and turnover within the monomictic Don Pedro Reservoir. Arsenic is predicted to be most bioavailable and toxic in the reservoir's summer hypolimnion. 7

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Section: High-resolution Transmission Electron Microsopymentioning

confidence: 87%

Section: Bulk Sample Characterizationmentioning

confidence: 99%

Section: Arsenian Pyrite In Source Rocksmentioning

confidence: 99%

See 1 more Smart Citation

Arsenic speciation in pyrite and secondary weathering phases, Mother Lode Gold District, Tuolumne County, California

Savage

Tingle

O’Day

et al. 2000

Applied Geochemistry

381

126

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“…Pyrite has a cubic crystal structure rather than an orthorhombic crystal structure found in marcasite. 33 In contrast, pyrrhotite has a relatively weak redox signal for sulfur. This could be due to it being predominantly S 2− rather than S 2 2− which could be why the cathodic signal at −0.1 V is so weak.…”

Section: Uv-vis Spectroscopymentioning

confidence: 99%

Dissolution of pyrite and other Fe–S–As minerals using deep eutectic solvents

et al. 2017

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a Processing sulfur containing minerals is one of the biggest sources of acute anthropogenic pollution particularly in the form of acid mine drainage. This study attempts to show an innovative method for processing sulfide-based minerals. It is shown that pyrite can be solubilised by both electrochemical oxidation and reduction in a deep eutectic solvent (DES) Ethaline, a mixture of choline chloride and ethylene glycol.A novel method is demonstrated to investigate the redox properties of minerals using a paste made from the mineral powder in a DES. The first bulk electrochemical dissolution of pyrite is shown without the formation of H 2 S or SO 2 . It is also shown that the soluble species, including elements such as arsenic, can be recovered electrochemically which could potentially decrease acid mine drainage. The electrochemical properties of other iron-sulfur and iron-arsenic minerals are also presented and compared to those of pyrite.

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“…The structure of marcasite is similar to that of arsenopyrite, and Brostigen and Kjekshus (1970b) and Tossell et al (1981) anticipated an extensive isomorphic substitution Asb = NS along the join. The structural relations between pyrite and marcasite have also been examined by Dódony et al (1996) who used the HRTEM technique. They found shear zones in pyrite and documented finescale intergrowths of micro-domains of pyrite and marcasite, on the scale of several planes of atoms.…”

Section: Crystal Structuresmentioning

confidence: 99%