Tapiolite

Tapiolite is a black mineral series that is an ore of niobium and tantalum. The tapiolite group includes tapiolite- or ferrotapiolite and tapiolite- or manganotapiolite. Tapiolite- is by far the more common of the two.
The minerals have a submetallic luster and a high specific gravity with tapiolite-Fe having a higher specific gravity versus 7.72 for tapiolite-Mn.
The mineral was named in 1863 after the forest god Tapio of Finnish mythology, and the original tapiolite material came from Sukula, Tammela, Kanta-Häme, Finland.
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.