Tapiolite

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Tapiolite
Tapiolite-121701.jpg
General
Category Mineral
Formula
(repeating unit)
(Fe, Mn)(Nb, Ta)2O6
Crystal system Tetragonal
Crystal class Ditetragonal dipyramidal (4/mmm)
H-M symbol: (4/m 2/m 2/m)
Space group P42/mnm
Identification
References [1]

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]

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[edit]

  1. ^ Mineralienatlas
  2. ^ a b Mindat tapiolite group
  3. ^ Ferrotapiolite in the Handbook of Mineralogy
  4. ^ Manganotapiolite in the Handbook of Mineralogy
  5. ^ a b Tapiolite-Fe on Mindat
  6. ^ a b 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