β-Uranophane from Zálesí

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Created on Saturday, 28 July 2012 10:17

Last Updated on Saturday, 28 July 2012 11:49

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β-Uranophane from Zálesí

Zálesí belongs to Czech best localities of uranium minerals. It became a target of some liquidation companies thanks to it in last 10 years. This companies liquidated again and again entry of the mine adit until today, when is all undergound inaccessable. We could thanks for it to our Polish "colleagues" too, who are publishing information about Czech opened mines on their web pages. Our best specimens of β-uranophane came out from the uranium mine in Zálesí. This mineral has composition Ca(UO₂)₂(HSiO₄)₂.5H₂O.

Uranophane is most common in Czech republic from the uranyl silicate company especially. Uranophane and β-uranophane are monoclinic and have the same chemical composition, but they have different structure. Type locality of β-uranophane is Jáchymov, where occurred very rare only. Its specimens of the highest quality came out from the locality Zálesí, where it was found on the 4th vein in the adit No. 2 especially. It occured here as a deep yellow prismatic crystals up to several mm size, which filled rarely cavities in quartz veinlets. Specimens are characterized by high esthetic quality. It often asociates with uranophane, which occurres on this locality as a fine needles of a pale yellow colour and it is easily possible to distinguish it from β-uranophane. The most reliable method to distuinguish this two minerals is by help of RTG diffraction methods. Both minerals are presented on the photography.

Uranophane in form of fine needle crystals in association with β-uranophane deep yellow crystals. Zálesí, adit No. 2. FOV 4 mm.