Tapiolite

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

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.[3][4][5] Tapiolite-(Fe) is by far the more common of the two.[6][7]

The minerals have a submetallic luster and a high specific gravity with tapiolite-Fe having a higher specific gravity (7.90)[6] versus 7.72 for tapiolite-Mn.[7]

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.[3][8]

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.[9]

  • Crystal structure of tapiolite
    Crystal structure of tapiolite
  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ Mineralienatlas
  3. ^ a b Mindat tapiolite group
  4. ^ Ferrotapiolite in the Handbook of Mineralogy
  5. ^ Manganotapiolite in the Handbook of Mineralogy
  6. ^ a b Tapiolite-Fe on Mindat
  7. ^ a b Tapiolite-Mn on Mindat
  8. ^ webmineral Tapiolite
  9. ^ P. Cerny et al. "The tantalite-tapiolite gap: natural assemblages versus experimental data" Canadian Mineralogist 30 (1992) 587 free download