Calcite passivation by gypsum: the role of the cooperative effect
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In this paper, the overgrowth of gypsum (CaSO4·2H2O) on calcite (CaCO3), used as a substrate, has been obtained in order to verify the hypothesis of a crystallographic fit between the two phases.Abstract:
The overgrowth of gypsum (CaSO4·2H2O) on calcite (CaCO3), used as a substrate, has been obtained in order to verify the hypothesis of a crystallographic fit between the two phases. Lattice coincidences show that many orientations of gypsum with respect to calcite can occur. Experimentally, only two among these are fulfilled during the early stages of growth, the selection criterion reasonably being the adhesion energy. Moreover, it has been shown that the presence of calcium carbonate as a specific surface impurity in solution modifies the growth habit of gypsum acting on the growth rate and surface morphology of some gypsum forms. At high concentration, the calcium carbonate in solution promotes the twinning of gypsum according to the Montmartre law.read more
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Calcium Carbonate Polymorphs Growing in the Presence of Sericin: A New Composite Mimicking the Hierarchic Structure of Nacre
Linda Pastero,Dino Aquilano +1 more
TL;DR: In this article, the effect of sericin on calcite and aragonite growth morphology has been studied experimentally, emphasizing the morphological effects of the sericins on calcites.
Journal ArticleDOI
Potential effects of the shape of gypsum aggregates on the early sulfation of marble and travertine
TL;DR: In this paper, the effects of the initial growth of gypsum crusts on calcareous substrates are studied by simulating acid attacks on marble and travertine test specimens, evaluating the potential mechanical actions exerted by the shape of newly grown aggregates.
Journal ArticleDOI
Epitaxies of Ca-sulfates on calcite (CaCO3). I. Gypsum {010} on calcite {10.4} form: epi-twins of gypsum induced by the calcite substrate
TL;DR: In this paper , the 3D-epitaxy of the {010} pinacoid of deposited gypsum (CaSO4·2H2O) on the substrate of a calcite rhombohedron is described, in order to give a theoretical background to the replacement of calcite by...
References
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Journal ArticleDOI
A refinement of the crystal structure of gypsum CaSO4.2H2O
W. F. Cole,C. J. Lancucki +1 more
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Gypsum Overgrowths Passivate Calcite to Acid Attack
TL;DR: Exposure of calcite to sulfuric acid is shown to lead to the rapid formation of an overlayer of calcium sulfate (gypsum) which completely passivates the surface against further reaction and dissolution.
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The Inhibition of Calcite Dissolution/Precipitation: Mg2+ Cations
TL;DR: In this paper, the dissolution of calcite under conditions of high pH (8.0--9.0) is shown to be strongly inhibited by the presence of magnesium (Mg[sup 2+]) cations.
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The dissolution of calcite in aqueous solution at pH < 4: kinetics and mechanism
TL;DR: In this paper, the dissolution kinetics of calcium carbonate in acidic aqueous solution were investigated using a calcite crystal in one wall of a rectangular duct, through which reactant flows under laminar conditions, and positioning either an amperometric or potentiometric detector electrode immediately adjacent to and downstream of the crystal.
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Structural morphology of gypsum (CaSO4·2H2O), brushite (CaHPO4·2H2O) and pharmacolite (CaHAsO4·2H2O)
W.M.M. Heijnen,P. Hartman +1 more
TL;DR: In this article, a uniform description of the crystal structures of gypsum, brushite and pharmacolite is presented from a PBC analysis leading to the following F forms: {020, {011, {⦶1}11, 120, and ⦶ 1}22.