Mobilization of Tl-Hg-As-Sb-(Ag,Cu)-Pb sulfosalt melts during low-grade metamorphism in the Alpi Apuane (Tuscany, Italy)

Biagioni, Cristian; D’Orazio, Massimo; Vezzoni, Simone; Dini, Andréa; Orlandi, Paolo

doi:10.1130/g34211.1

Cited by 45 publications

(38 citation statements)

References 10 publications

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“…1a). A similar behavior was observed for Hg-bearing metamorphic pyrite, where Hg partitions into the low-temperature melt (<420 °C, greenschist facies) and recrystallizes as complex Tl-Hg-As-Sb-(Ag,Cu)-Pb sulfosalts in pyrite samples from Alpi Apuane (Biagioni et al 2013). These analyses also plot above the solubility limit (in the NPs field), close to Hg/As = 1 (Fig.…”

Section: Mercurymentioning

confidence: 66%

“…1b). Similarly to Hg, Tlbearing NPs in pyrite were observed in metamorphic settings, suggesting that metamorphism induced the mobilization of multimetallic melts (Biagioni et al 2013). These representative Tl-As analyses plot homogenously above the indicated Tl/As = 1, over range of As concentrations from tens to tenthousands of parts per million.…”

Section: Mercurymentioning

confidence: 99%

“…The identification of particulate Hg and Tl in pyrite in low-temperature metamorphic rocks by Biagioni et al (2013) demonstrates that lowtemperature recrystallization processes involving trace element-rich pyrite are one of the most important factors controlling the post-entrapment mobilization of these metals (Fig. 1).…”

Section: Role Of Fluid Composition and Temperaturementioning

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: Mercurymentioning

confidence: 66%

Section: Mercurymentioning

confidence: 99%

Section: Role Of Fluid Composition and Temperaturementioning

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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“…Recently, new occurrences of thallium minerals have been reported from China (e.g. Lanmuchang, Guizhou Province - Xiao, 2001; Xiangquan, Anhui Province - Zhou et al, 2005) and Italy (Vulcano island, Sicily - Campostrini et al, 2011; Monte Arsiccio mine, Tuscany - Biagioni et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Structure of Pb-rich chabournéite from Jas Roux, France

Biagioni

Moëlo

Favreau

et al. 2015

Acta Crystallogr Sect B

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The crystal structure of a specimen of `Pb-rich' chabournéite from Jas Roux, Hautes-Alpes, France, with the chemical formula obtained by electron microprobe analysis of Ag(0.04 (1))Tl(2.15 (2))Pb(0.64 (1))Sb(5.12 (1))As(5.05 (1))S(17.32 (5)), has been solved by X-ray single-crystal diffraction on the basis of 36,550 observed reflections (with F(o) > 4σF(o)) with a final R1 = 0.074. Pb-rich chabournéite is triclinic P1, with unit-cell parameters a = 8.5197 (4), b = 42.461 (2), c = 16.293 (8) Å, α = 83.351 (2), β = 90.958 (2), γ = 84.275 (2)°, V = 5823 (3) Å(3). Its structural formula is close to [Tl2(Pb(0.8)Tl(0.1)Sb(1.1))](Sb(4.1)As(4.9))S17, with Z = 8. Its crystal structure is formed by the alternation of two pairs of slabs along the b axis, deriving from the SnS and PbS archetypes, respectively. 104 independent cation sites and 136 S sites occur in the unit cell. Slab interfaces show the alternation, along c, of Tl sites, ninefold coordinated, with Pb, Sb or mixed/split (Pb,Sb) and (Pb,Tl) sites. Within the slabs, 72 independent M(3+) sites (M(3+) = As, Sb) occur. Considering M(3+)-S bond distances shorter than 2.70 Å, MS3 triangular pyramidal groups are condensed according to various M(m)S(n) chain fragments (`polymers'). The solution of the crystal structure of chabournéite allows its comparison with the closely related homeotypes protochabournéite and dalnegroite.

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“…commun., 1989) and dalnegroite (Nestola et al, 2009). Triangles: protochabournéite (A and B correspond to analyses given in Orlandi et al, 2013). Square: boscardinite (4977 and 4989 correspond to analyses of type boscardinite given in Orlandi et al, 2012; the remaining analyses are discussed in the text).…”

Section: Resultsmentioning

confidence: 99%

Lead-antimony sulfosalts from Tuscany (Italy). XVIII. New data on the crystal-chemistry of boscardinite

Biagioni

Moëlo

2017

Mineral. mag.

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Boscardinite, ideally TlPb4(Sb7As2)Σ9S18, has been described recently as a new homeotypic derivative of baumhauerite, found at Monte Arsiccio mine, Apuan Alps, Tuscany, Italy. New findings of boscardinite in different mineral associations of this deposit have allowed the collection of new crystal-chemical data. Electron-microprobe analysis of the crystal used for the single-crystal X-ray diffraction study gave (in wt.%): Ag 1.81(5), Tl 12.60(21), Pb 17.99(12), Hg 0.14(5), As 9.36(12), Sb 33.60(27), S 23.41(30), Cl 0.06(1), total 98.97(100). On the basis of ΣMe = 14 apfu, it corresponds to Ag0.42Tl1.52Pb2.14Hg0.02 (Sb6.82As3.08)Σ9.90S18.04Cl0.04. With respect to the type specimen, these new findings are characterized by a strong Pb depletion, coupled with higher Tl contents, and a significant As enrichment. The single crystal X-ray diffraction study of this (Tl,As)-enriched boscardinite confirms the structural features described for the type sample. The unit-cell parameters are a = 8.1017(4), b = 8.6597(4), c = 22.5574(10) Å, α = 90.666(2), β = 97.242(2), γ = 90.850(2)°, V = 1569.63(12) Å3, space group Pī. The crystal structure was refined down to R1 = 0.0285 on the basis of 6582 reflections with Fo > 4σ(Fo). Arsenic is dominant in three MeS3 sites, compared to one in type boscardinite. The main As-enrichment is observed in the sartorite-type sub-layer. Owing to this chemical peculiarity, (Tl,As)-rich boscardinite shows alternation, along b, of Sb-rich sites and As-rich sites; this feature represents the main factor controlling the 8 Å superstructure. The chemical variability of boscardinite is discussed; the Ag increase observed here gets closer to stoichiometric AgTl-Pb4(Sb14As6)Σ20S36 (Z = 1), against possible extension up to AgTl2Pb6(Sb15As4)Σ19S36 for type boscardinite

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Mobilization of Tl-Hg-As-Sb-(Ag,Cu)-Pb sulfosalt melts during low-grade metamorphism in the Alpi Apuane (Tuscany, Italy)

Cited by 45 publications

References 10 publications

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

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

Structure of Pb-rich chabournéite from Jas Roux, France

Lead-antimony sulfosalts from Tuscany (Italy). XVIII. New data on the crystal-chemistry of boscardinite

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