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Formula: (Ca,K,Na)2-x(Ti,Nb)2(Si4O12)(OH,O)2.4H2O
Cyclosilicate (ring silicate), vuoriyarvite group,
labuntsovite supergroup,
titanium- and niobium- bearing
mineral
Crystal system: Monoclinic
Specific gravity: 2.73 measured, 2.72 calculated
Hardness: 5
Streak: White
Colour: White, colourless, pale brownish
Luminescence: Not fluorescent under UV
Common impurities: K,Na
Environments
Pegmatites
Hydrothermal environments
Localities
At the type locality, the Lovchorrite Mine, Hackman Valley, Yukspor Mt, Khibiny Massif, Murmansk Oblast, Russia,
tsepinite-Ca was found in the abandoned mine. It occurs in the hydrothermally altered zone of a large
aegirine - nepheline -
K-feldspar
pegmatite, and is associated mainly with
microcline, aegirine,
natrolite, kentbrooksite,
kupletskite, manganese-rich
lamprophyllite,
fluorapatite, catapleiite,
ancylite-(Ce),
ancylite-(La),
fluorapophyllite,
leucophanite and
chabazite-Ca. The tsepinite-Ca is late hydrothermal and occurs
in cavities after leaching of rinkite, the probable source of Ti, Nb and Ca.
Tsepinite-Ca forms coarse long-prismatic to needle-shaped and usually split crystals which are transparent,
colourless to white and pale brownish, up to 0.2 x 0.6 x 5 mm3 in size and form aggregates up to 1 cm
across
(Neues Jahrbuch für Mineralogie - Monatshefte, 2003 (10) 461-480).
Tsepinite-Ca from the Lovchorrite Mine -
Image
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