Tapiolite

Tapiolite [(Fe, Mn)(Nb, Ta)2O6] is a black mineral series that is an ore of niobium and tantalum. The tapiolite group includes tapiolite-(Fe) or ferrotapiolite and tapiolite-(Mn) or manganotapiolite.[2][3][4] Tapiolite-(Fe) is by far the more common of the two.[5][6]

Tapiolite
General
CategoryMineral
Formula
(repeating unit)		(Fe, Mn)(Nb, Ta)2O6
Crystal systemTetragonal
Crystal classDitetragonal dipyramidal (4/mmm)
H-M symbol: (4/m 2/m 2/m)
Space groupP42/mnm
Identification
References[1]

The minerals have a submetallic luster and a high specific gravity with tapiolite-Fe having a higher specific gravity (7.90)[5] versus 7.72 for tapiolite-Mn.[6]

The mineral was named in 1863 after the forest god Tapio of Finnish mythology, and the original tapiolite material came from Sukula, Tammela, Tavastia Proper, Finland.[2][7]

Tapiolite is very close to columbite and tantalite. Those minerals have the same chemical composition, but different crystal symmetry orthorhombic for tantalite or columbite and tetragonal for tapiolite.[8]

  • Crystal structure of tapiolite.

References
  1. Mineralienatlas
  2. Mindat tapiolite group
  3. Ferrotapiolite in the Handbook of Mineralogy
  4. Manganotapiolite in the Handbook of Mineralogy
  5. Tapiolite-Fe on Mindat
  6. Tapiolite-Mn on Mindat
  7. webmineral Tapiolite
  8. P. Cerny et al. "The tantalite-tapiolite gap: natural assemblages versus experimental data" Canadian Mineralogist 30 (1992) 587 free download


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