Pyrite Framboid Formation Chemistry

2021 ◽  
pp. 191-221
Author(s):  
David Rickard
Keyword(s):  
Crystal Growth ◽  
Iron Sulfide ◽  
Solid Surfaces ◽  
Isotopic Tracers ◽  
Pyrite Crystal ◽  
Iron Mineral ◽  
Iron Sulfide Minerals ◽  
Pyrite Formation ◽  
Major Route ◽  
Framboid Formation

Pyrite forms mainly through two routes: (1) the reaction between FeS species and polysulfides, and (2) the reaction of FeS species and H2S. Both of these reactions produce framboidal pyrite, and the mechanisms have been confirmed both kinetically and through the use of isotopic tracers. Aqueous Fe2+ does not appear to react directly with aqueous polysulfide species to produce pyrite, and the S-S bond in aqueous S2(-II) is normally split by aqueous Fe2+ to produce aqueous FeS and sulfur. The FeS moiety involved in pyrite formation may be provided by aqueous FeS or =FeS groups on solid surfaces. The reaction with surface =FeS occurs with any iron mineral in a sulfidic environment, including the relatively scarce iron sulfide minerals, mackinawite and greigite, nanoparticulate FeS, and pyrite itself. The reaction with surface =FeS sites on pyrite is a major route for pyrite crystal growth. The extreme insolubility of pyrite is one of the fundamental reasons for its particular involvement in framboid formation as well as for the ubiquity of framboids.

A theoretical study of adsorption on iron sulfides towards nanoparticle modeling

2020 ◽  
Vol 22 (40) ◽  
pp. 23258-23267
Author(s):  
Miroslav Kolos ◽  
Daniel Tunega ◽  
František Karlický
Keyword(s):  
Iron Sulfide ◽  
Theoretical Study ◽  
Sulfide Minerals ◽  
Adsorption Properties ◽  
Zero Valent Iron ◽  
Polar Molecules ◽  
Iron Sulfides ◽  
Iron Sulfide Minerals

The adsorption properties of two iron sulfide minerals (mackinawite and pyrite) and zero-valent iron with respect to two small polar molecules (H2O and H2S) and trichloroethylene (TCE) were modeled.

Mercury removal from water by iron sulfide minerals. An electron spectroscopy for chemical analysis (ESCA) study

1979 ◽  
Vol 13 (9) ◽  
pp. 1142-1144 ◽  
Author(s):  
James R. Brown ◽  
G. Michael Bancroft ◽  
William S. Fyfe ◽  
Ronald A. N. McLean
Keyword(s):  
Chemical Analysis ◽  
Electron Spectroscopy ◽  
Iron Sulfide ◽  
Sulfide Minerals ◽  
Mercury Removal ◽  
Iron Sulfide Minerals

The X-Ray Analysis of Uranium Ores for Iron Sulfide Minerals

1981 ◽  
Vol 25 ◽  
pp. 113-115
Author(s):  
A. J. Durbetaki ◽  
R. H. Carlson ◽  
T. F. Quail
Keyword(s):  
Hydrogen Peroxide ◽  
Iron Sulfide ◽  
Sulfide Minerals ◽  
Ore Deposits ◽  
X Ray Diffraction ◽  
X Ray ◽  
Iron Sulfide Minerals ◽  
Xrd Method

Hydrogen peroxide is used to extract uranium by the in situ leaching of sandstone ore deposits containing uraninite (UO2). Since FeS2 minerals, marcasite and pyrite, also occur in these deposits and they consume hydrogen peroxide in their oxidation, it is important to determine their concentration.A quantitative X-ray diffraction (XRD) method was therefore developed in order to monitor the concentration of marcasite and pyrite in sandstone ores.

Organic-Inorganic Nanocomposites Based on Iron Containing Clusters and Biomolecules

1995 ◽  
Vol 48 (4) ◽  
pp. 783 ◽  
Author(s):  
P Chan ◽  
W Chuaanusorn ◽  
M Nesterova ◽  
P Sipos ◽  
TG Stpierre ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Chondroitin Sulfate ◽  
Iron Sulfide ◽  
Nucleation And Growth ◽  
Protein Cage ◽  
Structural Order ◽  
Nucleation Sites ◽  
Inorganic Nanocomposites ◽  
Higher Temperature ◽  
Inorganic Clusters

Biopolymers, such as the protein ferritin and the polysaccharides chondroitin sulfate and chitosan, have been used to control the nucleation and growth of nanoscale iron(III) hydroxide clusters. The biopolymers can provide nucleation sites, that in some cases are spatially defined by the shape of the polymer, and/or defined volumes within which crystal growth of the iron(III) hydroxide can proceed. The product inorganic clusters are bound to the organic polymers which both keep them in solution and prevent aggregation. The morphology of the clusters (spheres or rods) and the uniformity of their dimensions are determined by the biopolymer chosen. The temperature of formation is shown to have an effect on the structure of the clusters, a higher temperature resulting in larger inorganic clusters with a higher degree of structural order. Iron(III) hydroxide clusters in ferritin cages can be partially transformed to iron sulfide by reaction with H2S gas while remaining in the protein cage.

Evidence for the involvement of betaproteobacterial Thiobacilli in the nitrate-dependent oxidation of iron sulfide minerals

2006 ◽  
Vol 58 (3) ◽  
pp. 439-448 ◽  
Author(s):  
Suzanne C.M. Haaijer ◽  
Marlies E.W. Van der Welle ◽  
Markus C. Schmid ◽  
Leon P.M. Lamers ◽  
Mike S.M. Jetten ◽  
...  
Keyword(s):  
Iron Sulfide ◽  
Sulfide Minerals ◽  
Iron Sulfide Minerals

scholarly journals Bistability in the redox chemistry of sediments and oceans

2020 ◽  
Vol 117 (52) ◽  
pp. 33043-33050
Author(s):  
Sebastiaan J. van de Velde ◽  
Christopher T. Reinhard ◽  
Andy Ridgwell ◽  
Filip J. R. Meysman
Keyword(s):  
Iron Sulfide ◽  
Redox Chemistry ◽  
Small Perturbations ◽  
Evolutionary Transitions ◽  
Positive Feedbacks ◽  
Iron Sulfur ◽  
Iron Sulfide Minerals ◽  
History Of ◽  
Redox Transitions ◽  
Marine Productivity

For most of Earth’s history, the ocean’s interior was pervasively anoxic and showed occasional shifts in ocean redox chemistry between iron-buffered and sulfide-buffered states. These redox transitions are most often explained by large changes in external inputs, such as a strongly altered delivery of iron and sulfate to the ocean, or major shifts in marine productivity. Here, we propose that redox shifts can also arise from small perturbations that are amplified by nonlinear positive feedbacks within the internal iron and sulfur cycling of the ocean. Combining observational evidence with biogeochemical modeling, we show that both sedimentary and aquatic systems display intrinsic iron–sulfur bistability, which is tightly linked to the formation of reduced iron–sulfide minerals. The possibility of tipping points in the redox state of sediments and oceans, which allow large and nonreversible geochemical shifts to arise from relatively small changes in organic carbon input, has important implications for the interpretation of the geological rock record and the causes and consequences of major evolutionary transitions in the history of Earth’s biosphere.

Nucleation of Framboids

2021 ◽  
pp. 222-234
Author(s):  
David Rickard
Keyword(s):  
Growth Phase ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Lag Phase ◽  
Surface Energies ◽  
Diffusion Limited ◽  
Critical Supersaturation ◽  
Unlimited Growth ◽  
Major Route ◽  
Framboid Formation

Framboid microcrystals, which are intrinsically similar in size and habit within any individual framboid, must have all nucleated and grown at the same time. The formation of many thousands of equidimensional and equimorphic microcrystals in framboids is the fundamental evidence for burst nucleation. This is conventionally described by the LaMer model, which is characterized by (1) a lag phase before nucleation becomes significant; (2) burst nucleation where the rate of nucleation increases exponentially and may be completed in seconds; and (3) a short growth phase where nucleation becomes again insignificant. The growth phase is limited by the diffusion of Fe and S in stagnant, diffusion limited environments. By contrast, individual pyrite crystals evidence isolated nucleation and unlimited growth in advecting systems. The reaction with surface =FeS provided by sulfidized iron oxyhydroxides may a major route for producing individual pyrite crystals, rather than framboids, especially in sediments. Framboid formation by the nucleation of pyrite in solution can be described by classical nucleation theory (CNT), which leads to results consistent with observed critical supersaturation ranges, critical nucleus radius, and surface energies.

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