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Title: Reactions forming pyrite and marcasite from solution: 1. Nucleation of FeS sub 2 below 100C

Abstract

Reaction paths for nucleation and growth of pyrite and marcasite from solution have been investigated experimentally. Conditions were chosen to avoid the precipitation of metastable Fe-S phases which can act as precursors for FeS{sub 2} formation. The experiments indicate that FeS{sub 2} nucleation is extremely slow below 100C. Instead of FeS{sub 2} nuclei, the reaction of ferrous ions and polysulfide ions produces initially amorphous FeS. Although the nucleation of FeS{sub 2} is inhibited below 100C, pyrite and marcasite can grow from solutions devoid of polysulfides and undersaturated with respect to possible Fe-S precursor phases. The inability of pyrite to rapidly nucleate explains high supersaturation with respect to pyrite and marcasite in anoxic environments. Although pyrite is the stable Fe-S phase in these environments, it will not control the Fe{sup 2+} and H{sub 2}S (or HS{sup {minus}}) concentrations until its growth rate exceeds the dissolution rate of far more soluble, metastable FeS precursor phases.

Authors:
;  [1]
  1. (Pennsylvania State Univ., University Park (United States))
Publication Date:
OSTI Identifier:
6005696
Resource Type:
Journal Article
Journal Name:
Geochimica et Cosmochimica Acta; (United States)
Additional Journal Information:
Journal Volume: 55:6; Journal ID: ISSN 0016-7037
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; MARCASITE; NUCLEATION; PRECIPITATION; PYRITE; AQUEOUS SOLUTIONS; CHEMICAL REACTION KINETICS; CRYSTAL GROWTH; DISPERSIONS; KINETICS; MINERALS; MIXTURES; REACTION KINETICS; SEPARATION PROCESSES; SOLUTIONS; SULFIDE MINERALS; 580000* - Geosciences

Citation Formats

Schoonen, M.A.A., and Barnes, H.L. Reactions forming pyrite and marcasite from solution: 1. Nucleation of FeS sub 2 below 100C. United States: N. p., 1991. Web. doi:10.1016/0016-7037(91)90122-L.
Schoonen, M.A.A., & Barnes, H.L. Reactions forming pyrite and marcasite from solution: 1. Nucleation of FeS sub 2 below 100C. United States. doi:10.1016/0016-7037(91)90122-L.
Schoonen, M.A.A., and Barnes, H.L. Sat . "Reactions forming pyrite and marcasite from solution: 1. Nucleation of FeS sub 2 below 100C". United States. doi:10.1016/0016-7037(91)90122-L.
@article{osti_6005696,
title = {Reactions forming pyrite and marcasite from solution: 1. Nucleation of FeS sub 2 below 100C},
author = {Schoonen, M.A.A. and Barnes, H.L.},
abstractNote = {Reaction paths for nucleation and growth of pyrite and marcasite from solution have been investigated experimentally. Conditions were chosen to avoid the precipitation of metastable Fe-S phases which can act as precursors for FeS{sub 2} formation. The experiments indicate that FeS{sub 2} nucleation is extremely slow below 100C. Instead of FeS{sub 2} nuclei, the reaction of ferrous ions and polysulfide ions produces initially amorphous FeS. Although the nucleation of FeS{sub 2} is inhibited below 100C, pyrite and marcasite can grow from solutions devoid of polysulfides and undersaturated with respect to possible Fe-S precursor phases. The inability of pyrite to rapidly nucleate explains high supersaturation with respect to pyrite and marcasite in anoxic environments. Although pyrite is the stable Fe-S phase in these environments, it will not control the Fe{sup 2+} and H{sub 2}S (or HS{sup {minus}}) concentrations until its growth rate exceeds the dissolution rate of far more soluble, metastable FeS precursor phases.},
doi = {10.1016/0016-7037(91)90122-L},
journal = {Geochimica et Cosmochimica Acta; (United States)},
issn = {0016-7037},
number = ,
volume = 55:6,
place = {United States},
year = {1991},
month = {6}
}