Leonite [K2Mg(SO4)2·4H2O], konyaite [Na2Mg(SO4)2·5H2O] and syngenite [K2Ca(SO4)2·H2O] fromTausoare Cave, Rodnei Mts, Romania | Mineralogical Magazine | Cambridge Core

Tausoare Cave is renowned in Romania for its gypsum and mirabilite speleothems. Of interest are the white crystalline speleothems formed on the floor of the ‘Sala de Mese’ (Dining Room) that were previously described as consisting of mirabilite. The samples we collected reveal crystals of two different habits. One shows the characteristic mirabilite fibrous crystals (cotton-like speleothem) while the other formed bladed and short prismatic crystals which comprise the delicate ‘cave flowers’. The mineral association was characterized by means of X-ray analysis, scanning electron microscopy and electron microprobe. Beside thenardite (dehydration product of mirabilite) we also identified three sulphate minerals: leonite [K2Mg(SO4)2·4H2O], syngenite [K2Ca(SO4)2·H2O] and konyaite [Na2Mg(SO4)2·5H2O]. Of these, leonite and konyaite have never been reported in a cave environment. This paper describes the mineralogy of this particular sulphate deposit and offers some viewpoints on the crystallogenesis.

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