Gold deposition on pyrite and the common sulfide minerals: An STM/STS and SR-XPS study of surface reactions and Au nanoparticles

Reduction of gold(III) chloride to gold(0) on silicate surfaces

“…In addition, it is been reported that precipitated metallic gold nanoparticles tend to aggregate, forming larger particles [15], which can cause additional problems in detection by spot analysis methods. Fig.…”

“…However, literature on the interaction of gold with mineral surfaces is generally concentrated on sulfide minerals [15], while studies of silicates are limited in number and have largely proven inconclusive [14,[16][17][18][19][20][21][22][23]. Several mechanisms for the interaction between gold complexes and silica have been proposed, but there remains a controversy regarding whether the complex ion forms a chemical bond on the silicate surface, or whether sorption occurs simply as a result of electrostatic interaction.…”

“…A good deal of attention has been paid to the interaction between gold and sulfide minerals; see [15] and references cited therein. More recent investigations have coupled electrochemical investigations, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) (both laboratory and synchrotron-based), and also quantum chemistry calculations and have successfully revealed the mechanisms of gold deposition on sulfide minerals [24,25].…”

“Invisible” silver and gold in supergene digenite (Cu1.8S)

“…Recent scanning tunneling microscopy (STM) and synchrotron X-ray photoelectron spectroscopy (SR-XPS) studies have confirmed surface electrochemical potential effects for the accumulation of "invisible" Au and Ag in Cu-Fe-As-S sulfides under hydrothermal conditions (Mikhlin and Romanchenko, 2007). Ab-initio calculations by Reich et al (2003Reich et al ( , 2004 suggested that the defect energy of replacing an Fe atom by a Au atom in pyrite is lowered by $1 eV if two or more As atoms are in the vicinity.…”

Arsenopyrite weathering under conditions of simulated calcareous soil

“…4a) Nesbitt and Muir 1998;Schaufuss et al 2000). The highenergy tail rising at~709 eV probably reflects the presence of minor Fe(II)-O and/or Fe(III)-AsS and Fe(III)-O contributions, which have been observed for vacuum-fractured surfaces (Schaufuss et al 1998b;Mikhlin and Romanchenko 2007). The Fe2p 3/2 spectrum of the weathered sample exhibits suggested contributions from different iron surface species (Fig.…”