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Formula: CsLi2AlSi4O10F2
Phyllosilicate (sheet silicate), trioctahedral mica group,
mica group, cesium- and
lithium- bearing mineral
Crystal System: Monoclinic
Specific gravity: 3.25 measured, 3.234 calculated
Hardness: 3
Streak: White
Colour: Colourless, white
Environments
Localities
At the Lac Moblan pegmatite, Baie-James, Jamésie, Nord-du-Québec, Québec, Canada, the main
pegmatite body of the Eastern block comprises a near-vertical
dyke that is simply zoned, with an aplitic border surrounding an
extensive zone of quartz–spodumene
pegmatite. Within this extensive unit, irregular
quartz- and lepidolite-
rich pods are developed that contain a rim of sokolovaite on compositionally zoned grains of
rubidium-bearing lepidolite.
Although not as common, sokolovaite is also observed as discrete, zoned grains inside fractures cutting through
granular masses of lepidolite. Minerals associated with sokolovaite
include rubidium-bearing
lepidolite, albite,
quartz and pollucite
(CM 47.2.337–349).
At the type locality, the Dara-i-Pioz Massif, Districts of Republican Subordination, Tajikistan, one of the
characteristic features of the massif is the wide variety of mica minerals
present, including
muscovite, annite,
tainiolite, polylithionite,
sokolovaite and orlovite.
(New Data on Minerals, 46. Moscow. 13-19).
Sokolovaite occurs as lamellar grains, more rarely fan-shaped and tree-like aggregates (from 0.02 to 2 mm) and
vein-like segregations. Associated minerals include aegirine,
baratovite, bismuth,
calcite, eudialyte,
fluorapatite, fluorite,
galena, leucosphenite,
microcline, neptunite,
pectolite, pekovite,
polylithionite,
pyrochlore group minerals,
sogdianite, sphalerite,
stillwellite-(Ce),
turkestanite and
zeravshanite.
The alkaline massif has boron-rich
granitoids intruding into
schists, crossed by
metasomatite and
pegmatite veins. The
pegmatites resulted from the differentiation of a silicic
melt to the point where saturation in boron is attained at T = 450 to 500°C,
and P less than 2 kbar.
Note: This locality is in a very remote area with hostile actors in the area. Recent access has been by helicopter
(Mindat).
Sokolovaite from the Dara-i-Poz Massif -
Image
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