ISSN

print 2570-7337
online 2570-7345

The occurrence of boltwoodite at the uranium deposit Kladská (Czech Republic)


Volume 24, issue 2 (2016), pages 298-303

Keywords

Abstract

Rare uranyl mineral boltwoodite, was found in the mine dump material of the abandoned uranium deposit Kladská, Slavkovský les Mountains, western Bohemia, Czech Republic. It occurs there as yellow to yellowish orange crystalline aggregates, veinlets and coatings in hydrothermally altered porphyric granite in association with uranophane. Its aggregates are usually composed from very thin acicular crystals. Well-formed boltwoodite crystals up to 2 mm in length in tiny cavities of crystalline aggregates of boltwoodite were observed only rarely. It is monoclinic, space group P21/m, the unit-cell parameters refined from X-ray powder diffraction data are: a 7.072(7), b 7.060(4), c 6.654(6) Å, β 105.06(7)° and V 320.8(5) Å3. Chemical analyses of boltwoodite correspond to the empirical formula (K0.62Pb0.04)Σ0.66(UO2)0.96(SiO3OH)1.00 . 1.5H2O on the basis of Si = 1 apfu. The Raman spectrum of boltwoodite and its tentative interpretation are given. The origin of boltwoodite at Kladská is interpreted as product of late hydrothermal fluids which altered uraninite and granitic rocks.

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