Tapiolite

Tapiolite
General
Category Mineral
Formula
(repeating unit)		 (Fe, Mn)(Nb, Ta)2O6

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.[1][2][3] Tapiolite-(Fe) is by far the more common of the two.[4][5]

The minerals have a submetallic luster and a high specific gravity with tapiolite-Fe having a higher specific gravity (7.90)[4] versus 7.72 for tapiolite-Mn.[5]

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.[1][6]

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.[7]

Crystal structure of tapiolite. 

References

  1. ↑ 1.0 1.1 Mindat tapiolite group
  2. ↑ Ferrotapiolite in the Handbook of Mineralogy
  3. ↑ Manganotapiolite in the Handbook of Mineralogy
  4. ↑ 4.0 4.1 Tapiolite-Fe on Mindat
  5. ↑ 5.0 5.1 Tapiolite-Mn on Mindat
  6. ↑ webmineral Tapiolite
  7. ↑ P. Cerny et al. "The tantalite-tapiolite gap: natural assemblages versus experimental data" Canadian Mineralogist 30 (1992) 587 free download