Die Entstehungsprozesse der Sulfidminerale und Goldspeziation in diesen Mineralen

• Antragsteller: Professor Juraj Majzlan, Ph.D.
• Fachliche Zuordnung: Mineralogie, Petrologie und Geochemie
• Förderung: Förderung von 2012 bis 2015
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 230745457

Mesothermal gold deposits comprise quartz veins with the refractory sulfides pyrite and arsenopyrite, and visible or invisible gold and they are an important source of gold for today's society. The formation processes, chemical composition, and elemental speciation of and within these veins has been studied extensively but gaps in the knowledge remain. In the proposed work, we intend to focus on two aspects of formation and speciation in such veins. Both of them are novel and highly promising of interesting and exciting insights into the processes that lead to ore formation deep within the Earth's crust. One of them is the study of crystal size distribution (CSD) of the ores. Using this approach, one may determine the saturation state of the fluids (i.e., qualitatively assess its deviation from equilibrium) during nucleation and crystallization. Conclusions about coupling or decoupling of the fluids with the source or host rocks may be drawn. Information can be gained about ripening of the crystals during the action of the fluids and therefore, albeit only qualitatively, about the duration of the hydrothermal pulses. Such information is of great interest, not only for mineralogists, but also for geologists and geophysists. The other aspect is the chemical speciation of the invisible gold in the refractory sulfides, especially in arsenopyrite. In addition to the previously used techniques, advances in instrumentation allow us to use X-ray absorption spectroscopy to determine the nearest neighbors of Au embedded in the refractory-sulfide matrix. We will work with a hypothesis that this gold forms nanoparticles and the multitude of results reported in the literature can be simply explained by variations in the size of such nanoparticles. Understanding of the gold speciation in the refractory sulfides may lead to an improvement of the existing technologies which are used to extract this gold.

• DFG-Verfahren: Sachbeihilfen