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Formula: Na2Cs4Zr3Si18O45.2H2O
Phyllosilicate (sheet silicate), cesium- and
zirconium- bearing mineral
Crystal System: Monoclinic
Specific gravity: 3.09 measured, 3.17 calculated
Hardness: 6
Streak: White
Colour: Colourless
Luminescence: No luminescence under short wave or long wave UV
Environments
Zeravshanite was approved in 2003 but to date (April 2025) it has been reported only from the type locality.
Localities
At the type locality, the Dara-i-Pioz Massif, Districts of Republican Subordination, Tajikistan, glaciers cover
significant areas of the massif, and most observations were made on rocks in the moraine of the Dara-i-Pioz glacier.
A feature of the massif is the presence of cesium minerals, including
kupletskite-(Cs),
telyushenkoite and zeravshanite.
Zeravshanite was found in rock composed mainly of quartz with
subordinate aegirine,
polylithionite,
reedmergnerite, pectolite
and other accessory minerals. This rock may be remnants of quartz cores of
pegmatites, or possibly fragments of veined bodies.
Well shaped black tabular crystals of aegirine up to 5 cm in size, large
lamellae of polylithionite up to 20 cm in size, semi-transparent
grass-green crystals of leucosphenite, lentil-shaped crystals of
stillwellite-(Ce), nests of coarse-grained
reedmergnerite, single crystals and intergrowths of white
microcline, pink to violet tabular segregations of
sogdianite-sugilite series
minerals up to 20 cm in size, and columnar to needle-shaped crystals of dark green hydrated
uranium-rich turkestanite are
sporadically impregnated in the quartz. Rarely
pyrochlore, neptunite,
galena, calcite,
kapitsaite-(Y),
berezanskite, tienshanite,
darapiosite, dusmatovite,
tadzhikite-(Ce),
baratovite, native bismuth,
sphalerite, fluorite,
fluorapatite and
fluorapophyllite are noted in this rock. Brown polymineral
aggregates, up to 25 cm in size, also occur in this rock and are composed predominantly of
pectolite with subordinate
aegirine, fluorite,
quartz, polylithionite,
neptunite, and very rarely by
pekovite and the cesium analogue of
polylithionite.
Zeravshanite was found very rarely in the edge zone of a pectolite
aggregate at the border with quartz in the form of grains, 0.02 to 0.1 mm in
size, and intergrowths or tabular individuals up to 0.2 mm in size
(New Data on Minerals, 39. Moscow. 21-25).
Zeravshanite from the Dar-i-Pioz Massif -
Image
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