Ixiolite

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.

Ixiolite
Ixiolite found in Mozambique
General
CategoryOxide minerals
Formula
(repeating unit)		(Ta,Nb,Sn,Mn,Fe)4O8[1] or (Ta,Mn,Nb)O2[2]
IMA symbolIx[3]
Strunz classification4.DB.25
Crystal systemOrthorhombic, some varieties might be monoclinic[4][1]
Crystal classDipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
Space groupPbcn[2]
Unit cella = 4.785, b = 5.758
c = 5.16 [Å]; Z = 4[2]
Identification
ColorSteel-grey, black
Crystal habitIrregular granular or inclusions, also as prismatic crystals; some varieties might be pseudoorthorhombic
TwinningUncommon on {013}
FractureIrregular/ uneven, sub-conchoidal
TenacityBrittle
Mohs scale hardness6 - 6+1⁄2
LusterSub-metallic
DiaphaneityOpaque
Specific gravity7.03 - 7.23
References[1][5][6][2]

Structure

Ixiolite was originally reported as crystallizing in the monoclinic crystal system.[5] Detailed studies of the scandium, tin and titanium rich varieties indicate that they form crystals in the orthorhombic system whereas tungsten ixiolite is monoclinic.[4]

Discovery and 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.[1]

Ixiolite is typically associated with feldspar, tapiolite, cassiterite, microlite, and rutile.[5]

Substitution and varieties

Trace elements include zirconium, hafnium, titanium and tungsten.[5]

As with other tantalum and niobium bearing minerals considerable substitution and a number of varieties exist. Substitutions in the formula are common and the varieties stannian ixiolite (tin), titanian ixiolite (titanium) and wolframian ixiolite (tungsten) have been reported.[4]

Scandium is present in many ixiolite sample 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.[4]

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.[7]

Further reading
  • Grice JD, Černý P, Ferguson RB (1972). "The Tanco pegmatite at Bernic Lake, Manitoba. II. Wodginite, tantalite, pseudo-ixiolite and related minerals" (PDF). The Canadian Mineralogist. 11: 609–642.
  • Grice JD, Ferguson RB, Hawthorne FC (1976). "The crystal structures of tantalite, ixiolite and wodginite from Bernic Lake, Manitoba I. Tantalite and ixiolite" (PDF). The Canadian Mineralogist. 14: 540–549.
  • The crystal structures of tantalite, ixiolite and wodginite from Bernic Lake, Manitoba; II, Wodginite

References
  1. Mindat.org - Ixiolite
  2. https://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Ixiolite Mineralienatlas
  3. Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  4. Wise, M.A.; Černý, P.; Falster, A.U. (1998). "Scandium substitution in columbite-group minerals and ixiolite" (PDF). Canadian Mineralogist. 36: 673–680.
  5. "Ixiolite" (PDF). Handbook of Mineralogy. Mineralogical Society of America. Archived from the original (PDF) on 10 October 2012. Retrieved 20 February 2013.
  6. Ixiolite data on Webmineral
  7. "Niobium-Tantalum". bgs.ac.uk. Retrieved 2 March 2013.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.