Oxy-vanadium-dravite
Oxy-vanadium-dravite is an IMA-recognized mineral species in the silicate class, with the chemical formula NaV₃(V₄Mg₂)(Si₆O₁₈)(BO₃)₃(OH)₃O.
It crystallizes in the hexagonal crystal system (space group R3m). It is a member of the Tourmaline structural group.
Key properties: Mohs hardness 7.5; specific gravity 3.32; Yellowish brownish green streak; Resinous luster; optically uniaxial.
IMA symbol Ovdrv, IMA status: approved, named in 1999.
Found in Cr-V-bearing calcite-quartz-diopside metamorphic rocks (granulite facies).
It is found associated with Quartz, calcite, Cr-V-bearing diopside, tremolite, di- and trioctahedral micas, Mg-Fe-V-Cr spinels, uvarovite-goldmanite, escolaite-karelianite.
Formerly known as “vanadium-dravite”. As an oxy-dravite with dominant vanadium in the Y and Z sites and magnesium the dominant divalent cation in Z.