A proposed new type of arsenian pyrite: Composition, nanostructure and geological significance

Deditius, Artur P.; Utsunomiya, Satoshi; Renock, Devon; Ewing, Rodney C.; Ramana, C. V.; Becker, Udo; Kesler, Stephen E.

doi:10.1016/j.gca.2008.03.014

Cited by 320 publications

(164 citation statements)

References 63 publications

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“…The other important factor that may regulate the amount of impurities in the pyrite structure is the size of the single crystals, which can be as small as 8 nm (Deditius et al 2008). Material science provides evidence for nanoparticulate semiconductors that experience self-purification resulting in the expulsion of the non-stoichiometric impurities/dopants toward the grain boundaries (Erwin et al 2005 and references therein).…”

Section: And References Therein) Substitution Of As For S In the Tetmentioning

confidence: 99%

“…While in synthetic systems the diffusion of the trace element (Mn) in semiconductors (CdSe) around temperature of 300 °C is negligible, 1-3 Å in short time (1 h) (Jamil and Shaw 1994), the equilibration and homogeneous distribution of the trace element within individual nanoparticles can be achieved over the geological time scale (Reich et al 2006;Deditius et al 2008;González-Jiménez et al 2015). Moreover, it was found that the formation of trace element-rich semiconducting NPswith homogeneously distributed doping element-is possible when the trace element is adsorbed on the growing surface of the nanocrystal (Erwin et al 2005).…”

Section: And References Therein) Substitution Of As For S In the Tetmentioning

confidence: 99%

“…Pyrite (FeS2) is the most common sulfide in the upper crust and can host from a few parts per million (ppm) up to weight percent (wt%) levels of heavy metals and metalloids such as As, Hg, Tl, and Cd (Rickard and Luther 2007;Deditius et al 2008;Lefticariu et al 2011;Keith et al 2016). Mineral processing of gold-bearing arsenian pyrite and combustion of pyrite-bearing coal result in the liberation of these toxic elements into the environment posing significant threats to the biosphere (Ikramuddin et al 1986;Wang et al 2010;Kolker 2012).…”

Section: Introductionmentioning

confidence: 99%

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Constraints on the solid solubility of Hg, Tl, and Cd in arsenian pyrite

Deditius

Reich²

2016

American Mineralogist

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Arsenic-rich (arsenian) pyrite can contain up to tens of thousands of parts per million (ppm) of toxic heavy metals such as Hg, Tl, and Cd, although few data are available on their solid solubility behavior. When a compilation of Hg, Tl, and Cd analyses from different environments are plotted along with As in a M(Hg, Tl, and Cd)-As log-log space, the resulting wedge-shaped distribution of data points suggests that the solid solubility of the aforementioned metals is strongly dependent on the As concentration of pyrite. The solid solubility limits of Hg in arsenian pyrite-i.e., the upper limit of the wedge-shaped zone in compositional space-are similar to the one previously defined for Au by ), whereas the solubility limit of Tl in arsenian pyrite is approximated by a ratio of Tl/As = 1. In contrast, and despite a wedge-shaped distribution of Cd-As data points for pyrite in Cd-As log-log space, the majority of Cd analyses reflect the presence of mineral particles of Cd-rich sphalerite and/or CdS. Based on these data, we show that arsenian pyrite with M/As ratios above the solubility limit of Hg and Tl contain nanoparticles of HgS, and multimetallic Tl-Hg mineral nanoparticles. These results indicate that the uptake of Hg and Tl in pyrite is strongly dependent on As contents, as it has been previously documented for metals such as Au and Cu. Cadmium, on the other hand, follows a different behavior and its incorporation into the pyrite structure is most likely limited by the precipitation of Cd-rich nanoparticulate sphalerite. The distribution of metal concentrations below the solubility limit suggests that hydrothermal fluids from which pyrite precipitate are dominantly undersaturated with respect to species of Hg and Tl, favoring the incorporation of these metals into the pyrite structure as solid solution. In contrast, the formation of metallic aggregates of Hg and Tl or mineral nanoparticles in the pyrite matrix occurs when Hg and Tl locally oversaturate with respect to their solid phases at constant temperature. This process can be kinetically enhanced by high-to-medium temperature metamorphism and thermal processing or combustion, which demonstrates a retrograde solubility for these metals in pyrite.

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Section: And References Therein) Substitution Of As For S In the Tetmentioning

confidence: 99%

Section: And References Therein) Substitution Of As For S In the Tetmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Constraints on the solid solubility of Hg, Tl, and Cd in arsenian pyrite

Deditius

Reich²

2016

American Mineralogist

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“…Figure 7 shows the typical elemental compositions of the Au-hosting arsenian pyrite and arsenopyrite. The data show no obvious relationship between Au and Fe in either the arsenian pyrite or the arsenopyrite (Figure 7(a)), but there is a negative correlation between As and S (Figure 7(b)) which suggests that the As in the structure of the arsenian pyrite has replaced S [10,11,47]. A similar negative correlation between As and S characterizes the arsenopyrite (Figure 7(b)).…”

Section: Arsenopyritementioning

confidence: 97%

The Au-Hosting Minerals and Process of Formation of the Carlin-Type Bojitian Deposit, Southwestern China

Pan

Cao

et al. 2017

Geofluids

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The recently discovered middle-sized Bojitian Carlin-type Au deposit is located in southwestern Guizhou Province, China, near the well-known Shuiyindong super-large-sized deposit. To improve the understanding on this deposit, here we investigate the minerals that host Au and the occurrence of Au in the deposit, using a combination of microscopic work and electron probe microanalysis (EPMA). Based on the results, the formation of the deposit was addressed. Results indicate that the dominant minerals that host Au include arsenian pyrite and arsenopyrite. Au in the cores of zoned pyrite exists mainly as natural nanoscale Au (Au 0 ), while Au in the rims exists mainly as solid solution Au (Au + ), but it likely also exists in the rims as natural nanoscale Au. The framboidal, coarsegrained, and banded pyrite types contain both natural nanoscale Au 0 and solid solution Au + . The arsenopyrite is of hydrothermal origin, and Au within the arsenopyrite exists as gold solution Au + . The Bojitian deposit was formed from As-bearing, H 2 S-rich, low-to-medium-temperature fluids that migrated along faults and other channels. Au that was already present in the strata or source beds migrated with the fluids in the form of Au(HS) − and ore-forming fluids were then formed in the reducing environment. The ore-forming fluids interacted with Fe-rich carbonates to form an abundance of Au-hosting arsenian sulfides.

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“…This deposit developed along near-vertical fracture zones in breccia and as stratiform bodies in acidleached pyroclastic rocks below a barren "steam-heated" granular silica cap (Longo 2000 ;Teal and Benavides 2010). Gold ore is hosted by quartz-rich alteration with pyrite, enargite, tennantite, covellite, minor amounts of Pb-sulfides, and native gold (Deditius et al 2008 ;Longo et al 2010 ;and references therein). Local zones with bonanza-grade gold ore host native gold in silica-oxide breccia and vuggy quartz intergrown with barite and limonite (Longo 2000 ).…”

Section: Aq5mentioning

confidence: 99%