The hexahydrite and ranciéite have been found in travertine or calcareous tufa, respectively in the Vyšné Ružbachy locality. They were identified by the X-ray diffraction methods. Hexahydrite occurs in the thin layers of white colour covering the weathering rocks. Chemical weathering of carbonate rocks is considered to be source of magnesium ions and sulphate can be of Triassic origin. Intergranular sources of carbonates for the soluble magnesium salts are alternatively assumed. Ranciéite forms the iron grey to black substances in the cavern of calc-tufa. Its occurrence is probably linked with precipitation from the thermal waters together with bacterial participation.