Formula: Na8[(UO2)(CO3)3](SO4)2.3H2O
Sulphate, uranyl mineral
Crystal System: Hexagonal
Specific gravity: 2.966 calculated
Hardness: 2
Streak: Very pale yellow
Colour: Light yellow to sulphuric yellow
RADIOACTIVE
Environments
Ježekite is a supergene, low-temperature mineral formed by
hydration-oxidation
weathering of uraninite associated with post-mining processes
(Mindat).
Localities
To date (October 2020) ježekite is known only from the type locality, the Geschieber vein, Svornost Mine, Jáchymov, Karlovy
Vary District, Karlovy Vary Region, Czech Republic, as a crystalline crust of thin, bladed prismatic crystals of
yellow to sulphuric yellow colour, associated with schröckingerite,
gypsum, čejkaite and
andersonite
(Mindat, https://hal.archives-ouvertes.fr/hal-01575308). Ježekite was approved in 2014. It is a
supergene, low-temperature mineral formed by hydration-oxidation weathering of
uraninite
associated with post-mining processes. It exhibits a bright greenish white fluorescence under both long-wave and short-wave UV
(https://hal.archives-ouvertes.fr/hal-01575308).
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