Ixiolite: Properties and Occurrences

Ixiolite is an accessory oxide mineral found in granitic pegmatites. It is an oxide with the general chemical formula (Ta, Nb, Sn, Mn, Fe)4O8 or (Ta, Mn, Nb)O2. It is a monoclinic-prismatic mineral containing iron, manganese, niobium, oxygen, tantalum, and tin. It was originally reported as crystallizing in the monoclinic crystal system.

General Information

  • Category: Oxide minerals
  • Formula: (Ta,Nb,Sn,Mn,Fe)4O8 or (Ta,Mn,Nb)O2.
  • Crystal system: Orthorhombic, some varieties might be monoclinic
  • Crystal class: Dipyramidal (mmm)

Fig: Ixiolite

Properties

Scandium is present in many ixiolite samples with percentages up to 4.0 percent Sc2O3, but usually less than one percent scandium oxide. High scandium ixiolites, containing from 4 to 19% scandium oxide are typically also rich in tin and titanium. Trace elements include zirconium, hafnium, titanium, and tungsten.

  • Color: Steel-grey, black
  • Twinning: Uncommon on {013}
  • Fracture: Irregular/ uneven, sub-conchoidal
  • Tenacity: Brittle
  • Mohs scale hardness: 6 – 6 1⁄2
  • Luster: Sub-metallic
  • Diaphaneity: Opaque
  • Specific gravity: 7.03 – 7.23

Occurrence

It was first described in 1857 for an occurrence at Skogsböle, Kimito Island, Finland. The name is for Ixion, the Greek mythological character related to Tantalus, as the mineral contains tantalum.

Ixiolite is typically associated with feldspar, tapiolite, cassiterite, microlite, and rutile.

Economic importance

Ixiolite together with microlite, tantalite, tapiolite, wodginite are the most important minerals mined for the element tantalum. Ixiolite contains about 69 % tantalum oxide (Ta2O5) and is a common constituent of coltan ore.

 

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