A Novel Route for the Synthesis of Mesoporous and Low-Thermal Stability Materials by Coupled Dissolution-Reprecipitation Reactions: Mimicking Hydrothermal Mineral Formation

Abstract

Replacement reactions ('pseudomorphism') commonly occur in Nature under a large range of conditions (T 25 to >600 ˚C; P 1 to >5 kbar). Whilst mineral replacement reactions are often assumed to proceed by solid-state diffusion of the metal ions through the mineral, many actually proceed via a coupled dissolution and reprecipitation (CDR) mechanism. In such cases, a starting mineral is dissolved into a fluid and this dissolution is coupled with the precipitation of a replacement phase across the reaction front. In cases where there are close relationships between the crystal structures of the parent and newly formed minerals, the replacement can be topotactic (interface-coupled dissolution and reprecipitation). The kinetics and chemistry of the CDR route are fundamentally different from solid-state diffusion and can be exploited i) for the synthesis of materials that are often difficult to synthesise via traditional methods and ii) to obtain materials with unique properties. This review highlights recent research into the use of CDR for such synthetic challenges. Emphasis has been given to i) the use of CDR to synthesise compounds with relatively low thermal stability such as the thiospinel mineral violarite ((Ni,Fe) 3 S 4 ), ii) preliminary work into use of CDR for the production of roquesite (CuInS 2 ), a potentially important photovoltaic component and, iii) examples where the textures resulting from CDR reactions are controlled by the nature and texture of the parent phase and the reaction conditions; these being the formation of micro-porous gold and three-dimensional ordered arrays of nanozeolite of uniform size and crystallographic orientation.

Bi-melt formation and gold scavenging from hydrothermal fluids: An experimental study

“…The textures of the replacement of pyrrhotite by magnetite show the characteristic features of interface-coupled dissolution-reprecipitation reactions (ICDRR; Brugger et al, 2010;Putnis, 2009;Xia et al, 2009a), including a sharp reaction front and porous magnetite product. In this case, the replacement is pseudomorphic and preserves (at least locally) the crystallographic orientation of the parent pyrrhotite.…”

Metal remobilization and ore-fluid perturbation during episodic replacement of auriferous pyrite from an epizonal orogenic gold deposit

“…Such replacement occurs when an externally-derived hydrothermal fluid comes into contact with pre-existing auriferous sulfide and sulfarsenide minerals with which they are undersaturated. These minerals begin to dissolve and form an interfacial layer of fluids at the mineral surfaces that is supersaturated with respect to a more stable product phase (Putnis, 2002(Putnis, , 2009Brugger et al, 2010;Qian et al, 2010Qian et al, , 2011Harlov et al, 2011;Altree-Williams et al, 2015). Comprehensive studies of replacement of auriferous iron sulfides and sulfarsenides are therefore crucial to decipher redistribution and reenrichment of gold (e.g., visible gold) plus other trace metals, and to monitor fluctuations in ore fluid fluxes and compositions, especially in the formation of giant and high-grade ore shoots (e.g., Tomkins and Mavrogenes, 2001;Tomkins et al, 2007;Morey et al, 2008;Cook et al, 2009Cook et al, , 2013Sung et al, 2009;Thomas et al, 2011;Rottier et al, 2016;Fougerouse et al, 2016Fougerouse et al, , 2017.…”

Experimental study of the formation of chalcopyrite and bornite via the sulfidation of hematite: Mineral replacements with a large volume increase

“…Recently we have used dissolution-reprecipitation reactions to synthesize, and study the formation of, a range of important sulfide ore minerals including pyrite (Qian et al 2010(Qian et al , 2013, violarite (Tenailleau et al 2006;Xia et al 2008Xia et al , 2009aBrugger et al 2010), and marcasite (Qian et al 2011). Chalcopyrite is principally a hydrothermal mineral, and forms in some cases in open cavities (veins), and in other cases as a replacement of preexisting minerals.…”