The recent weathering of uraninite from the Červená vein, Jáchymov (Czech Republic): a fingerprint of the primary mineralization geochemistry onto the alteration association
Abstrakt
Uraninite and the supergene minerals from the Červená hydrothermal uranium vein (Jáchymov ore district, Czech Republic) were studied. These supergene minerals represent alteration products of the joint weathering of uraninite and hypogene sulfide minerals, connected to the acid-mine drainage systems.
The weathering system is characterized by the high activity of Cu and REE, which control the composition of the resulting supergene minerals: commonly occurring are Cu-dominant uranyl sulfates of the zippeite group, Cu-dominant uranyl silicates or Y- and REE-containing uranyl-sulfates. The high ac tivity of Cu and REE is also reflected by the fact that both elements enter minerals, which are nominally Cu- or REE-free.
The alteration association was evaluated using the bond-valence approach, documenting distinct evolutionary trends during weathering.