Kirchhoffite

kirchhoffite

senkevichite

sokolovaite

stillwellite-(Ce)

Images

Formula: CsBSi2O6
Tectosilicate (framework silicate), zeolite group, cesium- and boron- bearing mineral
Crystal System: Tetragonal
Specific gravity: 3.622 measured, 3.639 calculated
Hardness: 6 to 6½
Streak: White
Colour: Colourless
Luminescence: Not fluorescent under UV
Environments

Pegmatites

Kitchhoffite was approved in 2009 but to date (April 2025) it has been reported only from the type locality.

Localities

The type locality, the Dara-i-Pioz Massif, Districts of Republican Subordination, Tajikistan, has a multiphase structure; the root is granite, and the central part of the massif is composed of aegirine quartz-bearing and quartz-free syenites. A small stock of cancrinite syenite occurs in the south western part of the massif. The massif contains a variety of hydrothermal rocks (albitites and fenites) and carbonatites. Abundant and varied mineralisation involving Cs, Li, B, Zr, REE, Ti, Ba is associated with the rocks of the massif. The cesium minerals include kirchhoffite, kupletskite-(Cs), telyushenkoite, sokolovaite, zeravshanite, senkevichite and mendeleevite-(Ce).
Kirchhoffite was found in a rock composed mainly of granular quartz with subordinate polylithionite, pectolite, fluorite, sogdianite, stillwellite-(Ce), leucosphenite, turkestanite, reedmergnerite, pyrochlore, microcline and kapitsaite-(Y).
Kirchhoffite occurs in pale brown polymineralic aggregates that reach up to 10 cm across. Those aggregates (which occur in quartz) consist mainly of pectolite, with subordinate quartz, fluorite, sokolovaite, baratovite, aegirine, polylithionite, stillwellite-(Ce), neptunite, pekovite, senkevichite and mendeleevite-(Ce). Kirchhoffite is generally intergrown with quartz and pectolite (CM 50.2.523-529).
Kirchhoffite from the Dara-i-Pioz Massif - Image

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