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Formula: NaMg3Cr6(Si6O18)(BO3)3(OH)3(OH)
Cyclosilicate (ring silicate), borosilicate,
tourmaline group
Crystal System: Trigonal
Specific gravity: 3.4
Hardness: 7 to 7½
Streak: Greyish green
Colour: Dark emerald-green to greenish black
Common impurities: Mn,Ti,V,Al,V,Ca
Environments
Localities
At the first recorded locality, the Velikaya Guba Deposit, Zaonezhie peninsula, Medvezhyegorsky District,
Republic of Karelia, Russia, chromium-dravite occurs in micaceous
metasomatites, associated with
chromium-bearing phengite,
tainiolite,
vanadium-bearing muscovite,
quartz and dolomite
(AM 69.210).
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