Chemistry:Tantalite

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Tantalite
Tantalite.jpg
Tantalite, Pilbara district, Australia
General
CategoryOxide minerals
Formula
(repeating unit)
(Fe,Mn)Ta2O6
Strunz classification4.DB.35
Crystal systemOrthorhombic
Crystal classDipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
Space groupPbcn (no. 60)
Identification
ColorDark black, iron-black to dark brown, reddish brown
CleavageGood in one direction
FractureSubconchoidal
Mohs scale hardness6-6.5
|re|er}}Submetallic to almost resinous
StreakBrownish-red to black
Specific gravity8.0+
References[1][2]

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

Manganotantalite from Alto do Giz, RN, Brazil

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 Democratic Republic of Congo, the United States (California , Colorado, Maine, and Virginia), and Zimbabwe. Brazil has the world's largest reserve of tantalite (52.1%).[5]

Sustainability

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

See also

References

  1. "TANTALITE (Iron Manganese Tantalum Niobium Oxide)". Galleries.com. http://www.galleries.com/Tantalite. 
  2. 2.0 2.1 Tantalite. Mindat.org (2011-09-07). Retrieved on 2011-10-30.
  3. P. Cerny (1992). "The tantalite-tapiolite gap: natural assemblages versus experimental data". Canadian Mineralogist 30: 587. http://rruff.geo.arizona.edu/doclib/cm/vol30/CM30_587.pdf. 
  4. Melcher, Frank (June 2008). "Fingerprinting of conflict minerals: columbite-tantalite ("coltan") ores". SGA News (23): 1. https://www.researchgate.net/publication/228401189. Retrieved 10 August 2016. 
  5. Papp, John F. (2006). "2006 Minerals Yearbook Nb & Ta". US Geological Survey. http://minerals.usgs.gov/minerals/pubs/commodity/niobium/#pubs. 
  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.

External links

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