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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
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 -
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