Journal of
GEOsciences
  (Formerly Journal of the Czech Geological Society)

Original Paper

Supergene mineralization of the Medvědín uranium deposit, Krkonoše Mountains, Czech Republic

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Abstract:
Supergene mineralization of the hydrothermal vein uranium deposit MedvÄ›dín (KrkonoÅ¡e Mts., northern Bohemia) is rather varied both in number of the mineral phases and their chemical variation. The supergene minerals agardite-(Y), autunite/metaautunite, dewindtite, churchite-(Y), kasolite, new unnamed phase Pb(Ce,REE)₃(PO4)₃(OH)₂ . nH₂O, parsonsite, phosphuranylite, plumbogummite, pseudomalachite, pyromorphite, saléeite, torbernite/metatorbernite and uranophane were studied using powder XRD, EPMA, IR-spectroscopic and thermal analysis, contributing significantly to the clarification of their crystal chemistry. The alteration mineral assemblage consisting mostly of uranyl phosphates and silicates exhibits relatively high contents of REE and Pb. Minerals with a composition corresponding to pure mineral end-members have not been observed; instead most of the studied phases represent members of isomorphic series. Studied mineral assemblage is a stable association in surface conditions resulting apparently from a long-term alteration of the primary uranium mineralization.
Dedicated to everlasting memory of outstanding mineralogist Ing. Zdeněk Mrázek, CSc. (1952-1984)