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 [1][2]
Manganotantalite from Alto do Giz, RN, Brazil

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).[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.[3]

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

Occurrence

Tantalite occurs in granitic pegmatites that are rich in rare-earth elements, and in placer deposits derived from such rocks.[4] 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%).[5] In 2006, 75% of world tantalite production came from Australia.[5]

Sustainability

The mining of tantalite causes many environmental and social problems in Democratic Republic of Congo.[6][7]

See also

Coltan mining and ethics

References

  1. ↑ "TANTALITE (Iron Manganese Tantalum Niobium Oxide)". Galleries.com. Retrieved 2011-10-25.
  2. 1 2 Tantalite. Mindat.org (2011-09-07). Retrieved on 2011-10-30.
  3. ↑ P. Cerny; et al. (1992). "The tantalite-tapiolite gap: natural assemblages versus experimental data" (PDF). Canadian Mineralogist. 30: 587.
  4. ↑ Melcher, Frank; et. al. (June 2008). "Fingerprinting of conflict minerals: columbite-tantalite ("coltan") ores" (PDF). SGA News (23): 1. Retrieved 10 August 2016.
  5. 1 2 Papp, John F. (2006). "2006 Minerals Yearbook Nb & Ta". US Geological Survey. Retrieved 2008-06-03.
  6. ↑ Coltan, Gorillas and cellphones. Cellular-news.com (2001-04-03). Retrieved on 2011-10-30.
  7. ↑ The Coltan Scandal. Geology.about.com (2010-07-04). Retrieved on 2011-10-30.
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