Interesting supergene Pb-rich mineral association from the Rovnost mining field, Jáchymov (St. Joachimsthal), Czech Republic
2011; Czech Geological Society; Linguagem: Inglês
10.3190/jgeosci.100
ISSN1803-1943
AutoresJ. Sejkora, Jakub Plášil, Ivana Cı́sařová, Radek Škoda, Jan Hloušek, F. Veselovský, Ivana Jebavá,
Tópico(s)Clay minerals and soil interactions
ResumoRich supergene mineral association with prevalence of Pb was found in a shallow gallery of the Rovnost mine, the Jáchymov (St.Joachimsthal) ore district, western Bohemia (Czech Republic).Mimetite occurs as colourless transparent flexible fibres up to 1 mm in length and up to 10 μm in diameter.The fibres form greyish white aggregates (up to 1 cm 2 in area) grown on the surface of gangue strongly affected by supergene alteration.The results of the single crystal X-ray diffraction study of mimetite with R 1 = 0.0381 are fully consistent with data reported previously for this mineral phase.According to electron microprobe study, interesting are namely elevated contents of SiO 4 (up to 0.16 apfu).Among the supergene minerals, cerussite, anglesite, wulfenite, philipsbornite-segnitite minerals, pyromorphite and metazeunerite were determined based on powder X-ray diffraction and electron microprobe analyses.The presence of U (~ 4 wt.% UO 3 ) and As (up to 4 wt.% As 2 O 5 ) in wulfenite is particularly noteworthy.Characteristic of the studied mineral association are elevated and omnipresent contents of F -.This mineral assemblage is considered to be a result of a long-term in-situ weathering in near-surface conditions.
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