This study focuses on the investigation of three uncommon complex iron sulfates – clairite, metavoltine, and voltaite – using Raman spectroscopy. The investigated specimens were formed at the burning coal dump Anna I (Alsdorf, Germany) due to alteration processes connected with the subsurface thermal activity. The results demonstrate proliferation of Raman bands and extraordinary strong spectral features connected with the specific crystal structures of these minerals. These data obtained here can serve as the reference material for the investigation of sulfate encrustation of fumarolic sulfide-weathering origin as well as can be implemented into the mineral databases important for the geological and mineralogical exploration of other extraterrestrial bodies.

Košek F., Edwards, H.G.M, Jehlička J. (2019): Raman spectroscopic vibrational analysis of the complex iron sulfates clairite, metavoltine, and voltaite from the burning coaldump Anna I, Alsdorf, Germany. Journal of Raman Spectroscopy (in press) (DOI).