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Formula: K2Mg[(UO2)(SO4)2]2.8H2O
Hydrated sulphate, uranyl mineral,
svornostite subgroup,
svornostite group
Crystal system: Orthorhombic
Specific gravity: 3.268 calculated
Hardness: 2
Streak: Pale yellow
Colour: Light yellow
Luminescence: Strong yellowish green fluorescence under both long wave and short wave UV
RADIOACTIVE
Environments
Svornostite-(K) is a relatively new mineral, approved in 2014 and to date (May 2025) reported only from the
type locality.
Localities
At the type locality, the Geschieber vein, Svornost Mine, Jáchymov, Karlovy Vary District, Karlovy Vary Region,
Czech Republic, svornostite-(K) occurs as weathering products from the post-mining alteration of
uraninite and sulphides in the Ag-Bi-Co-Ni-U bearing hydrothermal vein
deposit. It is a low-temperature, supergene mineral.
Associated minerals include geschieberite,
adolfpateraite, gypsum and
mathesiusite
(HOM, Mindat).
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