Columbite-(Mg)

columbite-(Mg)

ilmenorutile

cordierite

dravite

Images

Formula: MgNb₂O₆
Multiple oxide containing niobium, columbite group
Crystal System: Orthorhombic
Specific gravity: 5.17 measured, 5.23 calculated
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, andalusite, 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).

Back to Minerals