TAPIOLITE

    Class : Oxides and hydroxides
    Subclass : Oxides
    Crystal system : Tetragonal
    Chemistry : (Fe,Mn)(Ta,Nb)2O6
    Rarity : Fairly common


Tapiolite is a complex oxide of niobium, tantalum, iron and manganese, sometimes renamed "ferrotapiolite" to take into account the much rarer manganese pole, manganotapiolite. It is a mineral of albitized granitic pegmatites that is also well concentrated in alluvial placers. It was named after the god of the forest in Finnish mythology : Tapio or Tapiola. Tapiolite frequently forms beautiful automorphic crystals, short prismatic or equant, black to brownish-black in color. It is a very dense mineral (nearly 8). It is an accessory ore of niobium and tantalum.

Main photo : Tapiolite from Baixão da Laje mine, Parelhas, Rio Grande do Norte, Brazil © Terry Burtzlaff

Tapiolite in the World

The largest known crystals are specimens weighing up to 8 kg from the Muiâne pegmatite (Mozambique). Superb centimetre-sized crystals also come from the Angharf-nord pegmatite, near Tazenakht (Morocco). It is a common oxide in Australian (Greenbushes, Wodgina...), Brazilian (Praelhas, Conseilhero Pena), American (Custer, Paris, Topsham) and Finnish (Tammela, Kemiö) pegmatites in particular.

Right photo : Tapiolite from the Malpensata pegmatites, Italy © Angelo Brambilla

Tapiolite in France

In France, tapiolite is present in the pegmatites of Chanteloube, in the Ambazac mountains (Haute-Vienne), it is also reported in the pegmatites of Collioure (Pyrénées-Orientales).

Twinning

Twinning is very common on {013} and rarer on {101}.

Fakes and treatments

No fakes listed for this mineral species.



Hardness : 6 to 6.5
Density : 7.35 to 7.37
Fracture : Irregular
Streak : Brown-black


TP : Opaque
RI : -
Birefringence : -
Optical character : -
Pleochroism : None
Fluorescence : None


Solubility : -

Magnetism : NoneRadioactivity : Very low