Sokolovaite

sokolovaite

stillwellite-(Ce)

turkestanite

zeravshanite

Images

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

Pegmatites

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 quartzspodumene 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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