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Formula: (K,Ba,Na)2(Ti,Nb)2(Si4O12)(OH,O)2.3H2O
Cyclosilicate (ring silicate), vuoriyarvite group,
labuntsovite supergroup,
barium-, titanium- and
niobium- bearing mineral
Crystal system: Monoclinic
Specific gravity: 2.88 measured, 2.97 calculated
Hardness: 5
Streak: White
Colour: Colourless
Common impurities: Ba,Na
Environments
Pegmatites
Hydrothermal environments
Tsepinite-K occurs in cavities formed by hydrothermal alteration of alkaline
pegmatites. Associated minerals include other
labunstovite group minerals,
aegirine,
manganoneptunite,
natrolite, chabazite-Ca,
yofortierite, nontronite
and kaolinite minerals; tsepinite-K forms
pseudomorphs after murmanite
(HOM).
Localities
At the type locality, Karnasurt Mountain, Lovozersky District, Murmansk Oblast, Russia, tsepinite-K occurs
in an alkaline pegmatite as short-prismatic colourless
crystals up to 0.4 mm in length and as pseudomorphs after
murmanite. Associated minerals include
aegirine, chabazite-Ca,
manganoneptunite and
natrolite
(Mindat).
Tsepinite-K from Karnasurt Mountain -
Image
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