Tapiolite Fe, manganese">Mn)(niobium">Nb, tantalum">Ta)₂oxygen">O₆">iron.html" ;"title="iron">Fe, manganese">Mn)(niobium">Nb, tantalum">Ta)₂oxygen">O₆is 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.Mindat tapiolite group
/ref> Tapiolite-(Fe) is by far the more common of the two.
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/ref> The minerals have a submetallic luster and a high

specific gravity Relative density, also called specific gravity, is a dimensionless quantity defined as the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for solids and liquids is nea ...

with tapiolite-Fe having a higher specific gravity (7.90) 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,

Tavastia Proper Tavastia () or Tavastland may refer to: Regions * Häme (Swedish: ''Tavastland'', Latin: ''Tavastia'') * Tavastia (historical province) Tavastia (; ; ; also called ''Yam'' (Ямь) or ''Yem'' (Емь) in Russian sources) is a historical prov ...

Finland Finland, officially the Republic of Finland, is a Nordic country in Northern Europe. It borders Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of Bothnia to the west and the Gulf of Finland to the south, ...

. Tapiolite is very close to '' columbite'' and '' tantalite''. Those minerals have the same chemical composition, but different crystal symmetry

orthorhombic In crystallography, the orthorhombic crystal system is one of the 7 crystal systems. Orthorhombic Lattice (group), lattices result from stretching a cubic crystal system, cubic lattice along two of its orthogonal pairs by two different factors, res ...

for tantalite or columbite and

tetragonal In crystallography, the tetragonal crystal system is one of the 7 crystal systems. Tetragonal crystal lattices result from stretching a cubic lattice along one of its lattice vectors, so that the Cube (geometry), cube becomes a rectangular Pri ...

for tapiolite.P. Cerny et al. "The tantalite-tapiolite gap: natural assemblages versus experimental data" Canadian Mineralogist 30 (1992) 58
free download
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References

Tantalum minerals Niobium minerals Iron(II) minerals Manganese(II) minerals Oxide minerals Tetragonal minerals Minerals in space group 136 Minerals described in 1863 {{oxide-mineral-stub