Thorianite

Thorianite
Thorianite
	Group of interpenetrating twinned thorianite crystals from Ambatofotsy, Madagascar (size: 1.6 x 1.4 x 1.3 cm)
General
Category	Oxide mineral
Formula; (repeating unit)	Thorium oxide,ThO2
IMA symbol	Tho
Strunz classification	4.DL.05
Crystal system	Isometric
Crystal class	Hexoctahedral (m3m); H-M symbol:(4/m32/m)
Space group	Fm3m
Unit cell	a = 5.595 Å; Z = 4
Identification
Color	Dark gray, brown-black
Crystal habit	Cubic crystals, usually rounded to some degree in detrital deposits
Twinning	Penetration twins on {111} common
Cleavage	Poor/Indistinct
Fracture	Irregular to uneven, sub-conchoidal
Mohs scalehardness	6.5 – 7
Luster	Resinous, sub-metallic
Streak	Grey, grey green to black
Diaphaneity	Opaque, translucent on thin edges
Specific gravity	9.7
Optical properties	Isotropic
Refractive index	n = 2.20 – 2.35
Other characteristics	Radioactive
References

Thorianiteis a rarethorium oxide mineral,ThO₂.^[5]It was originally described byAnanda Coomaraswamyin 1904 as uraninite,^[6]but recognized as a new species byWyndham R. Dunstan.^[7]It was so named by Dunstan on account of its high percentage ofthorium;it also contains the oxides ofuranium,lanthanum,cerium,praseodymiumandneodymium.Heliumis present, and the mineral is slightly lessradioactivethanpitchblende,^[8]but is harder to shield due to its high energy gamma rays. It is common in thealluvialgem-gravels ofSri Lanka,where it occurs mostly as water worn, small, heavy, black, cubic crystals. The largest crystals are usually near 1.5 cm. Larger crystals, up to 6 cm (2.4 in), have been reported fromMadagascar.

Chemistry

Based on color, specific gravity and composition three types of thorianite are distinguished:^[9]

α-thorianite
β-thorianite
γ-thorianite

Thorianite anduraniniteform a completesolid solutionseries in synthetic and natural material.^[10]The division between the two species is at Th:U = 1:1 with U possibly making up to 46.50% and Th ranging up to 87.88%.^[11]Rare earths,chiefly Ce, substitute for Th in amounts up to 8% by weight.^[10]^[12]Ce is probably present as Ce⁴⁺.Complete series is known in synthetic material between CeO₂- PrO₂- ThO₂- UO₂.Small amounts of Fe³⁺and Zr also may be isomorphous with Th. Pb present is probably radiogenic.

Varieties

Aldanite– a variety of thorianite containing 14.9% to 29.0% UO₂and 11.2% to 12.5% PbO.^[13]
Uranothorianite^[14]
Thorianite Cerian^[15]^[16]
Thorianite La bearing^[15]

Occurrence

Usually found in alluvial deposits, beach sands, heavy mineral placers, andpegmatites.

Sri Lanka – In stream gravels,Galledistrict, Southern Province;Balangodadistrict; nearKodrugala,SabaragamuwaProvince; and from a pegmatite inBambarabotuwaarea.
India– Reported from beach sands ofTravancore(Kerala).^[17]
Madagascar– Found in alluvial deposits ofBetrokaandAndolobe.^[18]Also as very large crystals fromFort Dauphin;atAndranondamboand other localities.
Russia– In black sands of a gold placer onBoshogoch River,Transbaikalia,Siberia;in theKovdor MassifbyKovdor,Kola Peninsula;in theYenisei Range,Siberia.
United States– reported fromEaston,Pennsylvania;black sands inMissouri River,nearHelena,Montana;Scott River,Siskiyou County,California;^[19]black sands inNixon ForkandWisemandistricts,Alaska.^[20]^[21]
Canada– Reported with uraninite in a pegmatite onCharlebois Lake,east ofLake Athabasca;^[22]Uranon variety reported frompegmatiteand metesomatized zones in crystalline limestones from many locations inQuebecandOntario.^[23]
South Africa– Occurs withbaddeleyiteas an accessory incarbonatiteatPhalaborwa,Eastern Transvaal.^[24]
Democratic Republic of Congo-Kasaï region^[25]

References

^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.
^"Handbook of Mineralogy"(PDF).Archived fromthe original(PDF)on 2016-03-03.Retrieved2011-12-10.
^Mindat.org
^Webmineral data
^Frondel, C. (1958).Systematic Mineralogy of Uranium and Thorium.United States Government Printing Office.
^Coomaraswamy, A.K. (1904). "Uraninite".Spolia Zeylanica.Pt. 6 (2): 57.
^Dunstan, Wyndham R. (1904-03-31)."The occurrence of Thorium in Ceylon".Nature.69(1796): 510–511.Bibcode:1904Natur..69..510D.doi:10.1038/069510d0.S2CID 4032255.
^One or more of the preceding sentences incorporates text from a publication now in thepublic domain:Chisholm, Hugh,ed. (1911). "Thorianite".Encyclopædia Britannica.Vol. 26 (11th ed.). Cambridge University Press. p. 878.
^Kobayashi, M. (1912). "On the composition of thorianite".Tohoku Imp. Univ. Sci. Repts.1(Ist Ser): 201–206.
^^a ^bPalache, C.; H. Berman; C. Frondel (1944).Dana's System of Mineralogy, Volume 1.John Wiley and Sons, New York. pp. 620–622.
^ Heinrich, E. W. (1958).Mineralogy and Geology of Radioactive Raw Materials.McGraw-Hill.
^Graham, A. R. (1955). "CERIANITE CeO₂:A NEW RARE-EARTH OXIDE MINERAL ".Am. Mineral.40.
^Bespalov, M.M. (1941). "On discovery of a new mineral of the thorianite group [in Russian]".Sovietskaya Geologiya.II(6): 105–107.
^"Uranothorianite mineral information and data".Retrieved2007-06-28.
^^a ^b"Minerals with crystal structure determined".Archived fromthe originalon 2007-09-27.Retrieved2007-06-27.
^"ICSD for WWW: Details (Thorianite Cerian)".Retrieved2007-06-27.^{[permanent dead link‍]}
^Viswanathan, P. (1953). "Thorianite in Travancore".Mineral. Mag.88:282.
^Lacroix, A. (1923).Minéralogie de Madagascar.Augustin Challamel, éditeur, Librairie maritime et coloniale.
^George, D'Arcy (1949). "Mineralogy of Uranium and Thorium Bearing Minerals".USAEC Technical Information Service, Oak Ridge, Tennessee.RMO-563: 198.
^White, M. G. (1952).Radioactivity of Selected Rocks and Placer Concentrates from Northeastern Alaska.GS-C-195, Geological Survey.
^White, M. G.; J. M. Stevens (1953). "Reconnaissance For Radioactive Deposits In The Ruby-Poorman District, Ruby Quadrangle, Central Alaska,1949".USGS Report.TEI-192, Geological Survey: 62.Bibcode:1953usgs.rept...62W.doi:10.3133/tei192.
^Lang, A. H.; J. W. Griffith; H. R. Steacy (1962).Canadian Deposits of Uranium and Thorium.Geological Survey of Canada.
^Robinson, S. C.; A. P. Sabina (1955). "Uraninite And Thorianite From Ontario And Quebec".Am. Mineral.40.
^Hiemstra, S. A. (1955). "Baddeleyite from Phalaborwa, Eastern Transvaal".American Mineralogist.40:275–282.
^Ledoux, A. "Les roches cristallines du Kasai".Soc. Geol. Belgique Annales.40:C177.

External links

[1] 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.

[HBM-2] "Handbook of Mineralogy"(PDF).Archived fromthe original(PDF)on 2016-03-03.Retrieved2011-12-10.

[Mindat-3] Mindat.org

[Webmin-4] Webmineral data

[5] Frondel, C. (1958).Systematic Mineralogy of Uranium and Thorium.United States Government Printing Office.

[6] Coomaraswamy, A.K. (1904). "Uraninite".Spolia Zeylanica.Pt. 6 (2): 57.

[7] Dunstan, Wyndham R. (1904-03-31)."The occurrence of Thorium in Ceylon".Nature.69(1796): 510–511.Bibcode:1904Natur..69..510D.doi:10.1038/069510d0.S2CID 4032255.

[EB1911-8] One or more of the preceding sentences incorporates text from a publication now in thepublic domain:Chisholm, Hugh,ed. (1911). "Thorianite".Encyclopædia Britannica.Vol. 26 (11th ed.). Cambridge University Press. p. 878.

[9] Kobayashi, M. (1912). "On the composition of thorianite".Tohoku Imp. Univ. Sci. Repts.1(Ist Ser): 201–206.

[Dana-10] Palache, C.; H. Berman; C. Frondel (1944).Dana's System of Mineralogy, Volume 1.John Wiley and Sons, New York. pp. 620–622.

[11] Heinrich, E. W. (1958).Mineralogy and Geology of Radioactive Raw Materials.McGraw-Hill.

[12] Graham, A. R. (1955). "CERIANITE CeO₂:A NEW RARE-EARTH OXIDE MINERAL ".Am. Mineral.40.

[13] Bespalov, M.M. (1941). "On discovery of a new mineral of the thorianite group [in Russian]".Sovietskaya Geologiya.II(6): 105–107.

[14] "Uranothorianite mineral information and data".Retrieved2007-06-28.

[var-15] "Minerals with crystal structure determined".Archived fromthe originalon 2007-09-27.Retrieved2007-06-27.

[16] "ICSD for WWW: Details (Thorianite Cerian)".Retrieved2007-06-27.^{[permanent dead link‍]}

[17] Viswanathan, P. (1953). "Thorianite in Travancore".Mineral. Mag.88:282.

[18] Lacroix, A. (1923).Minéralogie de Madagascar.Augustin Challamel, éditeur, Librairie maritime et coloniale.

[19] George, D'Arcy (1949). "Mineralogy of Uranium and Thorium Bearing Minerals".USAEC Technical Information Service, Oak Ridge, Tennessee.RMO-563: 198.

[20] White, M. G. (1952).Radioactivity of Selected Rocks and Placer Concentrates from Northeastern Alaska.GS-C-195, Geological Survey.

[21] White, M. G.; J. M. Stevens (1953). "Reconnaissance For Radioactive Deposits In The Ruby-Poorman District, Ruby Quadrangle, Central Alaska,1949".USGS Report.TEI-192, Geological Survey: 62.Bibcode:1953usgs.rept...62W.doi:10.3133/tei192.

[22] Lang, A. H.; J. W. Griffith; H. R. Steacy (1962).Canadian Deposits of Uranium and Thorium.Geological Survey of Canada.

[23] Robinson, S. C.; A. P. Sabina (1955). "Uraninite And Thorianite From Ontario And Quebec".Am. Mineral.40.

[24] Hiemstra, S. A. (1955). "Baddeleyite from Phalaborwa, Eastern Transvaal".American Mineralogist.40:275–282.

[25] Ledoux, A. "Les roches cristallines du Kasai".Soc. Geol. Belgique Annales.40:C177.

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Thorianite

Contents

Chemistry

Varieties

Occurrence

See also

References

External links