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