The nature of micro- and nanocrystalline weathering products of sulfidic ores rich in As and Sb

• Applicant: Professor Juraj Majzlan, Ph.D.
• Subject Area: Mineralogy, Petrology and Geochemistry
• Term: from 2014 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 265185880

Sulfidic ores rich in arsenic (As) and antimony (Sb) are commonly exploited and serve as a source of many important metals, metalloids, and raw materials. Mining waste, either historical, recent, or currently produced, represents a major environmental load, even though the mining and processing technologies are steadily improving. Upon contact with atmosphere and hydrosphere, the sulfidic ores and the associated mining wastes weather, transform, and may pollute the environment. Here I propose to study crystal structures and crystal chemistry of selected weathering products of ores rich in As and Sb. They are common and often control the mobility and bioavailability of the toxic metalloids and metals. Yet, their nature is not known. Within this proposal, we will target phases from the systems Fe(III)-As(V)-S(VI)-H2O and (Cu,Zn,Ag,Bi,Fe)-Sb(V)-As(V)-H2O. Namely, we will study the ferric arsenates kankite, zykaite, and a suite of previously unknown phases from Rotgülden (Austria). From the latter system, we will inspect weathering products of tetrahedrite-tennantite ores. In addition to detailed optical microscopy and electron microprobe work, the focus of the work is in the diffraction techniques: high-resolution powder X-ray diffraction and electron precession diffraction. The latter method, in particular, will be used to decipher the crystal structure of the nanosized mixtures of weathering products. This project will be a benchmark study of nanosized natural weathering products. Although transmission electron microscopy has been used commonly in environmental studies, the possibility to solve crystal structures of all phases in a complex nanomixture is truly a revolution. It will open the door to an exhaustive and complete characterization of the weathering products and their transformation sequences.

• DFG Programme: Research Grants