Tantalite

oxide

columbite

Formula:
Tantalite-(Fe): Fe2+Ta2O6
Tantalite-(Mg): MgTa2O6
Tantalite-(Mn): Mn2+Ta2O6
These are multiple oxides containing tantalum, and members of the columbite group
Specific gravity:
Tantalite-(Fe): 8.2
Tantalite-(Mg): 6.7
Tantalite-(Mn): 8.1
Hardness:
Tantalite-(Fe): 6 - 6½
Tantalite-(Mg): 5½
Tantalite-(Mn): 6 - 6½
Streak:
Tantalite-(Fe): black-brown
Tantalite-(Mg): brown-red
Tantalite-(Mn): brown
Colour:
Tantalite-(Fe): Brownish black, black
Tantalite-(Mg): Black
Tantalite-(Mn): Black, brown
Solubility: Insoluble in hydrochloric and nitric acid; slightly soluble in sulphuric acid
Environments:

Pegmatites

Tantalite occurs in granitic rocks and pegmatites, associated with quartz, feldspar, mica, tourmaline, beryl, spodumene, cassiterite, hübnerite-ferberite, microlite and monazite.
Tantalite-(Fe) is an accessory mineral in granite pegmatites.
Tantalite-(Mg) occurs intergrown with tantalite-(Fe) and columbite-(Fe) as replacement rims on tantalite-(Mg) crystals in granite pegmatites.
Tantalite-(Mn) occurs in pegmatites and alluvial deposits.
Tantalite also may be found in granite.

Back to Minerals