Mineral description : Columbite - Tantalite

Columbite from Viitaniemi, Finland.

Columbite crystal from Kaatiala, Finland.

Columbite from Varuträsk.

Mineral class	Oxides : Perovskite - Pyrochlor - Columbite group.
Chemical formula	(Fe,Mn)(Nb,Ta)2O6
Crystal system	Orthorombic.
Habitus	Tabular or prismatic crystals, commonly twinned. Also as massive aggregates.
Cleavage	Distinct with a subconchoidal to uneven fracture.
Hardness	6
Density	5,3-8,1 (Tantalite 7,95-8,1)
Color	Black with sometimes iridiscent surfaces.
Streak	Dark red to black.
Luster	Submetallic to resinous, translucent to opaque.
Description
Occurance	Formed in granitic pegmatites.
Associates	With columbite : microcline. With tantalite : cleavelandite.
Notes	Heavier with more tantalum
Locations	Commonly in pegmatites. Tantalite : Finnbo quartz quarry, Falun. Utö iron mine, Stockholm archipelago. In pegmatite. Norrö quartz quarry, Stockholm archipelago. Varuträsk, Västerbotten. Columbite : Munkeby quartz quarry, Dragmark, Bohuslän. Timmerhult quartz quarry, Orust, Bohuslän. Högsbo quartz quarry, Göteborg. Norrö quartz quarry, Stockholm archipelago. Varuträsk, Västerbotten.

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