Ixiolite

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Ixiolite
Ixiolite-490369.jpg
Ixiolite found in Mozambique
General
CategoryOxide minerals
Formula
(repeating unit)		(Ta,Nb,Sn,Mn,Fe)4O8[1] or (Ta,Mn,Nb)O2[2]
Strunz classification4.DB.25
Crystal systemOrthorhombic, some varieties might be monoclinic[3][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][4][5][2]

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.

Structure[]

Ixiolite was originally reported as crystallizing in the monoclinic crystal system.[4] Detailed studies of the scandium, tin and titanium rich varieties indicate that they form crystals in the orthorhombic system whereas tungsten ixiolite is monoclinic.[3]

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.[4]

Substitution and varieties[]

Trace elements include zirconium, hafnium, titanium and tungsten.[4]

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.[3]

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.[3]

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.[6]

Further reading[]

  • Grice J D, Černý P, Ferguson R B (1972). "The Tanco pegmatite at Bernic Lake, Manitoba. II. Wodginite, tantalite, pseudo-ixiolite and related minerals" (PDF). The Canadian Mineralogist. 11: 609–642.CS1 maint: uses authors parameter (link)
  • Grice J D, Ferguson R B, Hawthorne F C (1976). "The crystal structures of tantalite, ixiolite and wodginite from Bernic Lake, Manitoba I. Tantalite and ixiolite" (PDF). The Canadian Mineralogist. 14: 540–549.CS1 maint: uses authors parameter (link)
  • The crystal structures of tantalite, ixiolite and wodginite from Bernic Lake, Manitoba; II, Wodginite

References[]

  1. ^ a b c d Mindat.org - Ixiolite
  2. ^ a b c d https://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Ixiolite Mineralienatlas
  3. ^ a b c d Wise, M.A., Černý, P., Falster, A.U. (1998). "Scandium substitution in columbite-group minerals and ixiolite" (PDF). Canadian Mineralogist. 36: 673–680.CS1 maint: uses authors parameter (link)
  4. ^ a b c d "Ixiolite" (PDF). Handbook of Mineralogy. Mineralogical Society of America. Retrieved 20 February 2013.
  5. ^ Ixiolite data on Webmineral
  6. ^ "Niobium-Tantalum". bgs.ac.uk. Retrieved 2 March 2013.
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