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Formula: MgNb2O6
Multiple oxide containing niobium,
columbite group
Specific gravity: 5.17
Hardness: 6½
Streak: Dark brown
Colour: Black to brownish black, in fine splinters translucent brownish red, in transmitted light brown to reddish
brown
Environments
Pegmatites
Metamorphic environments
Localities
At the type locality, the Muzeinaya pegmatite vein, Pyandzh River Valley, Gorno-Badakhshan, Tajikistan,
columbite-(Mg) occurs in the pegmatite, in
dolomitic marbles which have
been partly assimilated with the formation of cordierite,
dravite, spinel,
andalasite, kyanite and others.
The columbite-(Mg) occurs as acicular and tabular crystals 1 to 2 mm in size, with rough surfaces, and it is
commonly intergrown with ilmenorutile
(AM 48.1178-1184).
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