Khademite and rostite are rare orthorhombic minerals Al(SO4)F·5H2O and Al(SO4)OH·5H2O, respectively. Libušín is a type locality of rostite but recent studies have only confirmed the presence of khademite. New electron microprobe analyses of khademite from Libušín revealed a fluorine concentration of 8.12–8.18 wt.%, which is the highest ever found for khademite. Precise discrimination of structurally very similar sulfates is of high importance for geochemical studies and a combination of different analytical methods is preferred to reach this goal.
Košek F., Žáček V., Škoda R., Laufek F., Jehlička J. (2019): New mineralogical data for khademite (orthorhombic Al(SO4)F·5H2O) and the story of rostite (orthorhombic Al(SO4)OH·5H2O) from Libušín near Kladno, the Czech Republic. Journal of Molecular Structure 1175, 208-213. (DOI)