Columbite-(Mg)

columbite-(Mg)

ilmenorutile

cordierite

dravite

Images

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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