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Formula: KCr2(AlSi3O10)(OH)2
Phyllosilicate (sheet silicate),
dioctahedral mica subgroup,
mica group,
chromium-bearing mineral
Crystal System: Monoclinic
Specific gravity: 2.88 measured, 2.86 calculated
Hardness: 3
Streak: Whitish green
Colour: Emerald green
Environments
Localities
At Outokumpu, North Karelia, Finland, chromium-rich micas
including chromphyllite are formed by metamorphism at about 3.5 kbar pressure and 600oC
(DHZ).
At the type locality, Kaber's pit, Pokhabikha River Valley, Slyudyanka, Lake Baikal area, Irkutsk Oblast, Russia, chromphyllite,
which forms a solid solution series with muscovite, occurs as 0.3 to 0.4 mm plates and flakes,
commonly rich in chromite and eskolaite inclusions.
The chromphyllite occurs in the metamorphic complex, with
granulite facies metamorphism, in
chromium-enriched layers in quartzite. Associated
minerals include muscovite,
biotite-phlogopite,
uvarovite, chromium-bearing
dravite,
chromite-zincochromite,
eskolaite and, rarely, titanite and
rutile
(AM 83.652-653, DHZ).
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