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Formula: (Na,◻)2(Ti4+,Fe3+)4(Si2O6)2(Si3AlO10)(OH)4.H2O
Inosilicate (chain silicate), single chains, titanium-bearing mineral
Crystal System: Triclinic
Specific gravity: 2.77 measured, 2.76 calculated
Hardness: 5
Streak: White
Colour: Colourless to white
Luminescence: Weak yellow-green fluorescence under 240-400 nm short-wave UV
Solubility: Not reactive in 1:1 hydrochloric and nitric acid at room or higher temperature
Environments
Pegmatites
Hydrothermal environments
Paravinogradovite is a secondary mineral formed from
vinogradovite. It was approved in 2002 but to date (April 2025) it has
been reported only from the type locality.
Localities
At the type locality, the Northeast slope, Kukisvumchorr Mt, Khibiny Massif, Murmansk Oblast, Russia, specimens of
paravinogradovite were collected from a pegmatite
emplaced at the contact between a xenolith of corundum-bearing
hornfels and the enclosing
foyaite. The lenticular
pegmatite is asymmetrically zoned. There are four zones from
the contact with hornfels toward the contact with
foyaites:
(1) coarse-grained aegirine –
diopside – orthoclase rock with
altered nepheline and abundant disseminated
pyrochlore,
(2) a blocky K-feldspar zone,
(3) a rounded nepheline core with disseminated
ilmenite and pyrochlore and
(4) a banded medium- to coarse- grained biotite –
aegirine – diopside –
nepheline – feldspar rock.
In the pegmatite, there are two types of superimposed
alteration, occurring primarily within the nepheline zone. The earlier
albite-type alteration resulted in aggregates of tabular
albite with miarolitic cavities and disseminated bipyramidal
zircon. The later zeolite-type
alteration consists of aggregates of
analcime–natrolite. Both types of
alteration seem to involve late-stage hydrothermal infilling.
Paravinogradovite occurs in miarolitic cavities associated with the
albite-type alteration, growing directly on
albite. Carbonate-rich
fluorapatite, ancylite-(Ce),
natrolite and aegirine are closely
associated with paravinogradovite. Usually, aegirine and
paravinogradovite form radial aggregates. All miarolitic minerals are encrusted with fine flakes of a
glauconite-like mineral, which occasionally completely fills the miarolitic
cavity. Other associated species include nordstrandite,
anatase, fluorite,
galena and cerussite as a
pseudomorph after galena.
Paravinogradovite crystals contain very small inclusions of
vinogradovite.
Paravinogradovite forms fan-shaped aggregates of colourless to white columnar and acicular crystals up to
1.0 cm long
(CM 41.4.989-1002).
Paravinogradovite from Kukisvumchorr Mt -
Image
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