Pekovite

pekovite

sogdianite

turkestanite

tadzhikite

Images

Formula: SrB2Si2O8
Tectosilicate (framework silicate), strontium- and boron- bearing mineral
Crystal System: Orthorhombic
Specific gravity: 3.35 measured, 3.36 calculated
Hardness: 6½ to 7
Streak: White
Colour: White, colourless
Environments

Pegmatites

Pekovite 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, a glacier descends from the southern slope of the Igla Mountain, which is situated at the intersection of the Turkestan, Alai and Zeravshan mountain ranges, and fragments of alkaline rocks and pegmatites of the massif occur in the moraine of the glacier. The massif is known for very high contents of boron, hence a widespread and varied occurrence of boron minerals, including tienshanite, tadzhikite-(Ce), kapitsaite-(Y), maleevite and pekovite that were first described from this massif.
Pekovite was found in a block of quartz. The blocks are rounded and vary from 0.2 to 2.0 m across; they could be fragments of quartz cores of pegmatites or fragments of veins. They consist mainly of medium- to coarse- grained granulated quartz with disseminated large plates of polylithionite, crystals of microcline, pockets of pale yellow to pink reedmergnerite, randomly distributed, usually idiomorphic and almost black aegirine crystals, rare lenticular crystals of stillwellite-(Ce), grass-green crystals of leucosphenite, purple-pink plates of sogdianite, dark green elongate prismatic crystals of turkestanite with a high content of U4+ and H2O, and polymineralic pockets lined mainly by pectolite. Galena, calcite, kapitsaite-(Y), neptunite, sugilite, pyrochlore, eudialyte group minerals, tadzhikite-(Ce), baratovite, native bismuth, sphalerite, fluorite, fluorapatite, fluorapophyllite, zeravshanite and several unknown cesium-bearing minerals are less abundant in the quartz blocks. Pekovite occurs as anhedral equant grains from 0.05 to 0.2 mm, commonly intergrown with pectolite, quartz, highly strontian fluorite and aegirine (CM 42.1.107-119).
Pekovite from the Dara-i-Pioz Massif - Image

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