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Updated: Sep 18, 2025
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Preparation of Authigenic Pyrite from Methane-bearing Sediments for In Situ Sulfur Isotope Analysis Using SIMS
Published on: August 31, 2017
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Sulfur microenvironments as hotspots for biogenic pyrite formation
Fatih Sekerci1, Stefan Fischer2, Prachi Joshi1
1Geomicrobiology, Department of Geosciences, University of Tuebingen, Tuebingen, Germany.
Scientific Reports
|June 20, 2025
Summary
Elemental sulfur and sulfur-reducing bacteria promote pyrite formation. Sulfur particles act as hotspots, creating polysulfide-rich environments for biogenic pyrite precipitation.
Area of Science:
- Geochemistry
- Microbiology
- Mineralogy
Background:
- Pyrite (FeS2) is a key mineral in sedimentary environments, typically formed by sulfate-reducing bacteria (SRB).
- Previous studies often yield metastable iron sulfides (e.g., mackinawite) when using SRB for biogenic pyrite formation.
- The role of elemental sulfur in microbial pyrite synthesis remains less understood.
Purpose of the Study:
- To investigate the influence of elemental sulfur (S0) and microbial sulfur reduction on pyrite formation.
- To explore the potential of sulfur-reducing bacteria as an alternative to SRB for biogenic pyrite synthesis.
- To understand the microenvironmental conditions favoring pyrite precipitation.
Main Methods:
- Cultivation of Geobacter sulfurreducens with ferrihydrite and elemental sulfur at different Fe/S ratios (4:1 and 1:4).
- Analysis of mineral products formed under varying conditions.
- Morphological examination of pyrite formation on elemental sulfur surfaces.
Main Results:
- Mackinawite (FeS) formed at a high Fe/S ratio (4:1).
- Greigite (Fe3S4) and pyrite (FeS2) formed at a low Fe/S ratio (1:4) via the polysulfide pathway.
- Spherulitic pyrite particles nucleated and grew on elemental sulfur surfaces, preserving sulfur morphology.
Conclusions:
- Sulfur-reducing bacteria can act as sulfide sources for pyrite formation, complementing or replacing SRB.
- Elemental sulfur particles serve as critical hotspots for biogenic pyrite formation.
- Polysulfide-rich microenvironments and templating effects of sulfur particles drive heterogeneous pyrite precipitation.
Keywords:
Geobacter sulfurreducensBiogenic pyrite formationMicroenvironmentPolysulfidePyrite spherulesSulfidic conditionsMore Related Videos
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