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Formula: NaMg(SO4)F.2H2O
Hydrated sulphate
Crystal System: Monoclinic
Specific gravity: 2.42 measured, 2.414 calculated
Colour: Colourless
Solubility: Practically insoluble in cold water, dissolves in cold, weak hydrochloric acid
Environments
Sedimentary environments
Hydrothermal environments
Uklonskovite may be a product of supergene alteration of
kononovite
(Mindat).
Localities
At Le Cetine di Cotorniano Mine, Chiusdino, Siena Province, Tuscany, Italy, mineralisation in
brecciated dolomitic
limestone developed in Triassic (252 to 201 million years ago)
evaporitic deposits, which have been silicified by hydrothermal fluids circulating in the fault system; these fluids
deposited the stibnite mineralisation for which the mine is famous
(Mindat).
Minerals associated with uklonskovite include jurbanite,
rostite, tamarugite,
ferrinatrite and
sideronatrite
(HOM).
At the type locality, the Kushkanatau salt deposit, Lower Amu Darya River, Karakalpakstan, Uzbekistan,
uklonskovite occurs at a depth of 80 m in cavities in clays covering
a saline layer in Neogene (from about 26 million years ago to the present) rocks, associated with
polyhalite and glauberite; the
saline layers also contain blödite and
halite, and minor mirabilite,
thenardite, espomite,
hexahydrite and gypsum
(AM 50.520-521).
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