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Formula: K(AlSi3O8)
Tectosilicate (framework silicate), feldspar group,
paramorph
of liebermannite, sanidine,
microcline and
orthoclase
Specific gravity: 2.45 calculated
Environments
Kokchetavite is the metastable high-pressure paramorph, found within
a multiphase inclusion in clinopyroxene and
garnet
(Mindat).
Localities
At the type locality, the Lake Kumdikol diamond deposit, Lake Kumdikol, Prirechnoye, Zerendy, Akmola Region, Kazakhstan,
kokchetavite occurs as plates and prisms, 3 to 7 μm in size, within
clinopyroxene and
garnet in ultrahigh-pressure rocks. These rocks occur within ultrahigh-grade
granitic and biotite
gneiss. The peak metamorphic conditions for this complex are estimated to
be 5.8 to 6.5 GPa and 900 to 1100oC. Microdiamonds have been found
as inclusions in garnet, zircon and
clinopyroxene in many of the rocks of this complex. The sample containing
kokchetavite was collected from an underground microdiamond mine.
Kokchetavite is associated with zircon,
phlogopite, löllingite,
diopside, grossular-rich
garnet, phengite,
K-feldspar,
pyrrhotite, quartz,
titanite, K-cymrite,
cristobalite, clinopyroxene,
calcite and talc. It is thought to form
metastably from infiltrated melts, or from the dehydration of K-cymrite, which
was a high-pressure precipitate from infiltrated melts
(AM 90.1228-1229, Mindat).
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