Tantalite

Tantalite
Tantalite, Pilbara district, Australia
General
Category	Oxide minerals
Formula (repeating unit)	(Fe,Mn)Ta2O6
Strunz classification	4.DB.35
Crystal system	Orthorhombic
Crystal class	Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m)
Identification
Color	Dark black, iron-black to dark brown, reddish brown
Cleavage	Good in one direction
Fracture	Subconchoidal
Mohs scale hardness	6-6.5
Luster	Submetallic to almost resinous
Streak	Brownish-red to black
Specific gravity	8.0+
References

The mineral group tantalite [(Fe, Mn)Ta₂O₆] is the primary source of the chemical element tantalum. It is chemically similar to columbite, and the two are often grouped together as a semi-singular mineral called coltan or "columbite-tantalite" in many mineral guides. However, tantalite has a much greater specific gravity than columbite (8.0+ compared to columbite's 5.2). Iron-rich tantalite is the mineral tantalite-(Fe) or ferrotantalite and manganese-rich is tantalite-(Mn) or manganotantalite.

Tantalite is also very close to tapiolite. Those minerals have same chemical composition, but different crystal symmetry orthorhombic for tantalite and tetragonal for tapiolite.

Tantalite is black to brown in both color and streak. Manganese-rich tantalites can be brown and translucent.

Tantalite occurs in granitic pegmatites that are rich in rare-earth elements, and in placer deposits derived from such rocks. It has been found in Australia, Brazil, Canada, Colombia (Guainía and Vichada), Egypt, northern Europe, Madagascar, Namibia, Nigeria, Rwanda, the United States (California, Colorado, Maine, and Virginia), and Zimbabwe. Brazil has the world's largest reserve of tantalite (52.1%). In 2006, 75% of world tantalite production came from Australia.