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
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