Fluor-dravite

fluor-dravite

tourmaline

fluor-uvite

beryl

Images

Formula: NaMg₃Al₆(Si₆O₁₈)(BO₃)₃(OH)₃F
Borosilicate, tourmaline group, forms a series with fluor-uvite
Crystal System: Trigonal
Specific gravity: 3.120 calculated
Hardness: 7
Streak: Pale brown
Colour: Blackish brown
Luminescence: Not fluorescent under UV
Common impurities: Ca,Fe,Mn,Li
Environments

Pegmatites

Localities

At the type locality, the Crabtree mine, Spruce Pine, Mitchell county, North Carolina, USA, blackish-brown fluor-dravite occurs at the boundary of the pegmatite and the country rock, in association with K-feldspar, plagioclase, quartz, beryl, muscovite, garnet, biotite and fluorite. Crystals of fluor-dravite are anhedral, up to a few mm across, and occur as isolated grains (CM 49.57-62).

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