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Formula: Na8(Al6Si6)O24(SO4).2H2O
Tectosilicate (framework silicate), cancrinite group. A solid
solution is known to exist between cancrinite and vishnevite
with the principal substitutions being (CO3)2- by (SO4)2- and Ca for Na
(MM 81.5.1261–1277).
Crystal System: Hexagonal
Specific gravity: 2.42 to 2.42 measured, 2.37 calculated
Hardness: 5 to 6
Streak: White
Colour: Colourless, light blue, orange-yellow, white
Common impurities: Sr
Environments
Plutonic igneous environments
Pegmatites
Hydrothermal environments
Vishnevite occurs in poikilitic (a texture due to the presence of crystals enclosing inclusions of numerous
smaller crystals of a different mineral - (SS)
aegirine - nepheline -
sodalite
syenite and associated
pegmatites. Associated minerals include
aegirine, nepheline,
cancrinite, sodalite and
scolecite (HOM). It occurs as a
primary mineral and also as an alteration product of
nepheline
(Dana).
Localities
There are two co-type Localities, the Ilmen Nature Reserve and Kurochkin Log, Vishnevye Mountains, both at
Chelyabinsk Oblast, Russia,
At Kurochkin Log, Vishnevye Mountains, Chelyabinsk Oblast, Russia, vishnevite occurs in
pegmatites as an alteration and replacement of
nepheline, associated with
scolecite
and gibbsite
(AM 17.252 as wischnewite).
At the Ilmen Nature Reserve, Chelyabinsk Oblast, Russia, vishnevite occurs in
pegmatites as an alteration and replacement of
nepheline, associated with
natrolite
and cancrinite
(AM 17.252 as wischnewite).
At the Karnasurt Mountain and the Alluaiv Mountain, both in the Lovozersky District, Murmansk Oblast, Russia,
vishnevite occurs in poikilitic (a texture due to the presence of crystals enclosing inclusions of numerous
smaller crystals of a different mineral - (SS))
aegirine - nepheline -
sodalite
syenite and associated
pegmatites. It is found as veinlets 1 to 3 cm thick, as
prismatic
crystals in cavities, and as irregular granular aggregates that locally are replacements of
sodalite
(AM 73: 927-928).
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