Details
| Original language | English |
|---|---|
| Article number | 122253 |
| Number of pages | 13 |
| Journal | Chemical geology |
| Volume | 662 |
| Early online date | 25 Jun 2024 |
| Publication status | Published - 5 Sept 2024 |
Abstract
In this work, we investigated the extent of antimony (Sb) isotopic fractionation during weathering of stibnite at supergene conditions. Antimony isotope data have been obtained from secondary Sb minerals collected from Pezinok, Dobšiná (both Slovakia) and Allchar (North Macedonia) deposits and mine tailings. The Sb isotope compositions of sulfides and secondary Sb minerals formed on the primary stibnite [Sb2S3] or in mine tailings grains were compared with each other. Furthermore, we experimentally investigated Sb isotope fractionation during stibnite leaching with different acids. Our study reveals a large isotopic range for δ123Sb (from −0.50 to +0.69 ‰) for secondary Sb minerals. They are either isotopically indistinguishable or isotopically lighter than the primary stibnite. Isotopically indistinguishable weathering products likely formed by quantitative Sb transfer from stibnite to the secondary minerals, such as brandholzite [Mg(H2O)6[Sb(OH)6]2] from Pezinok. Isotopic fractionation towards lighter δ123Sb was observed for adsorption of Sb onto iron oxides. Distinctly isotopically lighter δ123Sb was observed in secondary Sb minerals tripuhyite [FeSbO4], chapmanite [Fe3+2Sb3+(Si2O5)O3(OH)], hydroxyferroromeite [Fe2Sb2O6(OH)], and stibiconite [Sb3O6OH] that either replace stibnite or formed in mine tailings from the pore solutions. These secondary minerals were likely generated by partial precipitation of Sb from aqueous solutions produced by dissolution of stibnite. In the leaching experiments with HCl and oxalic acid, Sb was leached without significant isotope effects during the first 2–3 days, followed by a drop of the dissolved Sb concentration associated with Sb isotope fractionation towards high δ123Sb in the leachate (by up to 0.5 ‰) after 4–7 days. We interpret these observations to be related to the precipitation of secondary Sb oxides with low δ123Sb, resulting in an isotopically heavy dissolved Sb pool. These findings are in agreement with previous results of isotopically heavy groundwater and mine drainage water with δ123Sb > +0.36 ‰ that may suggest that the ‘truly’ dissolved (operationally defined as <0.45 μm) Sb fraction in general may be isotopically heavy.
Keywords
- Fractionation, Oxidative leaching, Sb isotopes, Secondary minerals, Stibnite, Weathering
ASJC Scopus subject areas
- Earth and Planetary Sciences(all)
- Geology
- Earth and Planetary Sciences(all)
- Geochemistry and Petrology
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In: Chemical geology, Vol. 662, 122253, 05.09.2024.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Weathering-induced Sb isotope fractionation during leaching of stibnite and formation of secondary Sb minerals
AU - Kaufmann, Andreas B.
AU - Lazarov, Marina
AU - Horn, Ingo
AU - Števko, Martin
AU - Ðorđević, Tamara
AU - Kiefer, Stefan
AU - Weyer, Stefan
AU - Majzlan, Juraj
N1 - Publisher Copyright: © 2024 The Authors
PY - 2024/9/5
Y1 - 2024/9/5
N2 - In this work, we investigated the extent of antimony (Sb) isotopic fractionation during weathering of stibnite at supergene conditions. Antimony isotope data have been obtained from secondary Sb minerals collected from Pezinok, Dobšiná (both Slovakia) and Allchar (North Macedonia) deposits and mine tailings. The Sb isotope compositions of sulfides and secondary Sb minerals formed on the primary stibnite [Sb2S3] or in mine tailings grains were compared with each other. Furthermore, we experimentally investigated Sb isotope fractionation during stibnite leaching with different acids. Our study reveals a large isotopic range for δ123Sb (from −0.50 to +0.69 ‰) for secondary Sb minerals. They are either isotopically indistinguishable or isotopically lighter than the primary stibnite. Isotopically indistinguishable weathering products likely formed by quantitative Sb transfer from stibnite to the secondary minerals, such as brandholzite [Mg(H2O)6[Sb(OH)6]2] from Pezinok. Isotopic fractionation towards lighter δ123Sb was observed for adsorption of Sb onto iron oxides. Distinctly isotopically lighter δ123Sb was observed in secondary Sb minerals tripuhyite [FeSbO4], chapmanite [Fe3+2Sb3+(Si2O5)O3(OH)], hydroxyferroromeite [Fe2Sb2O6(OH)], and stibiconite [Sb3O6OH] that either replace stibnite or formed in mine tailings from the pore solutions. These secondary minerals were likely generated by partial precipitation of Sb from aqueous solutions produced by dissolution of stibnite. In the leaching experiments with HCl and oxalic acid, Sb was leached without significant isotope effects during the first 2–3 days, followed by a drop of the dissolved Sb concentration associated with Sb isotope fractionation towards high δ123Sb in the leachate (by up to 0.5 ‰) after 4–7 days. We interpret these observations to be related to the precipitation of secondary Sb oxides with low δ123Sb, resulting in an isotopically heavy dissolved Sb pool. These findings are in agreement with previous results of isotopically heavy groundwater and mine drainage water with δ123Sb > +0.36 ‰ that may suggest that the ‘truly’ dissolved (operationally defined as <0.45 μm) Sb fraction in general may be isotopically heavy.
AB - In this work, we investigated the extent of antimony (Sb) isotopic fractionation during weathering of stibnite at supergene conditions. Antimony isotope data have been obtained from secondary Sb minerals collected from Pezinok, Dobšiná (both Slovakia) and Allchar (North Macedonia) deposits and mine tailings. The Sb isotope compositions of sulfides and secondary Sb minerals formed on the primary stibnite [Sb2S3] or in mine tailings grains were compared with each other. Furthermore, we experimentally investigated Sb isotope fractionation during stibnite leaching with different acids. Our study reveals a large isotopic range for δ123Sb (from −0.50 to +0.69 ‰) for secondary Sb minerals. They are either isotopically indistinguishable or isotopically lighter than the primary stibnite. Isotopically indistinguishable weathering products likely formed by quantitative Sb transfer from stibnite to the secondary minerals, such as brandholzite [Mg(H2O)6[Sb(OH)6]2] from Pezinok. Isotopic fractionation towards lighter δ123Sb was observed for adsorption of Sb onto iron oxides. Distinctly isotopically lighter δ123Sb was observed in secondary Sb minerals tripuhyite [FeSbO4], chapmanite [Fe3+2Sb3+(Si2O5)O3(OH)], hydroxyferroromeite [Fe2Sb2O6(OH)], and stibiconite [Sb3O6OH] that either replace stibnite or formed in mine tailings from the pore solutions. These secondary minerals were likely generated by partial precipitation of Sb from aqueous solutions produced by dissolution of stibnite. In the leaching experiments with HCl and oxalic acid, Sb was leached without significant isotope effects during the first 2–3 days, followed by a drop of the dissolved Sb concentration associated with Sb isotope fractionation towards high δ123Sb in the leachate (by up to 0.5 ‰) after 4–7 days. We interpret these observations to be related to the precipitation of secondary Sb oxides with low δ123Sb, resulting in an isotopically heavy dissolved Sb pool. These findings are in agreement with previous results of isotopically heavy groundwater and mine drainage water with δ123Sb > +0.36 ‰ that may suggest that the ‘truly’ dissolved (operationally defined as <0.45 μm) Sb fraction in general may be isotopically heavy.
KW - Fractionation
KW - Oxidative leaching
KW - Sb isotopes
KW - Secondary minerals
KW - Stibnite
KW - Weathering
UR - http://www.scopus.com/inward/record.url?scp=85197097791&partnerID=8YFLogxK
U2 - 10.1016/j.chemgeo.2024.122253
DO - 10.1016/j.chemgeo.2024.122253
M3 - Article
AN - SCOPUS:85197097791
VL - 662
JO - Chemical geology
JF - Chemical geology
SN - 0009-2541
M1 - 122253
ER -