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Chemistry

Based on color, specific gravity and composition three types of thorianite are distinguished:⁵

• α-thorianite
• β-thorianite
• γ-thorianite

Thorianite and uraninite form a complete solid solution series in synthetic and natural material.⁶ The division between the two species is at Th:U = 1:1 with uranium possibly making up to 46.50% and thorium ranging up to 87.88%.⁷ Rare earths, chiefly cerium, substitute for thorium in amounts up to 8% by mass.⁸⁹ Cerium is probably present as Ce4+. Complete series is known in synthetic material between CeO2 - PrO2 - ThO2 - UO2. Small amounts of Fe3+ and zirconium also may be isomorphous with thorium. Lead present is probably radiogenic.

Varieties

• Aldanite – a variety of thorianite containing 14.9% to 29.0% UO2 and 11.2% to 12.5% PbO.¹⁰
• Uranothorianite¹¹
• Thorianite Cerian¹²¹³
• Thorianite La bearing¹⁴

Occurrence

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

• Sri Lanka – In stream gravels, Galle district, Southern Province; Balangoda district; near Kodrugala, Sabaragamuwa Province; and from a pegmatite in Bambarabotuwa area.
• India – Reported from beach sands of Travancore (Kerala).¹⁵
• Madagascar – Found in alluvial deposits of Betroka and Andolobe.¹⁶ Also as very large crystals from Fort Dauphin; at Andranondambo and other localities.
• Russia – In black sands of a gold placer on Boshogoch River, Transbaikalia, Siberia; in the Kovdor Massif by Kovdor, Kola Peninsula; in the Yenisei Range, Siberia.
• United States – reported from Easton, Pennsylvania; black sands in Missouri River, near Helena, Montana; Scott River, Siskiyou County, California;¹⁷ black sands in Nixon Fork and Wiseman districts, Alaska.¹⁸¹⁹
• Canada – Reported with uraninite in a pegmatite on Charlebois Lake, east of Lake Athabasca;²⁰ Uranon variety reported from pegmatite and metesomatized zones in crystalline limestones from many locations in Quebec and Ontario.²¹
• South Africa – Occurs with baddeleyite as an accessory in carbonatite at Phalaborwa, Eastern Transvaal.²²
• Democratic Republic of Congo - Kasaï region²³

See also

• Earth sciences portal

• Uraninite
• Thorite
• Classification of minerals
• List of minerals

External links

• Uraniumminerals.com
• Mindat.org

References

1. Frondel, C. (1958). Systematic Mineralogy of Uranium and Thorium. United States Government Printing Office. ↩

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

3. 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. https://zenodo.org/record/1429437 ↩

4. One or more of the preceding sentences incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Thorianite". Encyclopædia Britannica. Vol. 26 (11th ed.). Cambridge University Press. p. 878. /wiki/Public_domain ↩

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

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

7. Heinrich, E. W. (1958). Mineralogy and Geology of Radioactive Raw Materials. McGraw-Hill. ↩

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

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

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

11. "Uranothorianite mineral information and data". Retrieved 2007-06-28. http://www.mindat.org/min-4114.html ↩

12. "Minerals with crystal structure determined". Archived from the original on 2007-09-27. Retrieved 2007-06-27. https://web.archive.org/web/20070927022021/http://sdpd.univ-lemans.fr/minknown.html#T ↩

13. "ICSD for WWW : Details (Thorianite Cerian)". Retrieved 2007-06-27.[permanent dead link] http://icsdweb.fiz-karlsruhe.de/details.php?id%5B%5D=24439&PHPSESSID=734118bb8 ↩

14. "Minerals with crystal structure determined". Archived from the original on 2007-09-27. Retrieved 2007-06-27. https://web.archive.org/web/20070927022021/http://sdpd.univ-lemans.fr/minknown.html#T ↩

15. Viswanathan, P. (1953). "Thorianite in Travancore". Mineral. Mag. 88: 282. ↩

16. Lacroix, A. (1923). Minéralogie de Madagascar. Augustin Challamel, éditeur, Librairie maritime et coloniale. https://archive.org/details/MineralogieDeMadagascarTome3 ↩

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

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

19. White, M. G.; J. M. Stevens (1953). "Reconnaissance For Radioactive Deposits In The Ruby-Poorman District, Ruby Quadrangle, Central Alaska,1949" (PDF). USGS Report. TEI-192, Geological Survey: 62. Bibcode:1953usgs.rept...62W. doi:10.3133/tei192. https://digital.library.unt.edu/ark:/67531/metadc1050378/m2/1/high_res_d/report.pdf ↩

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

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

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

23. Ledoux, A. "Les roches cristallines du Kasai". Soc. Geol. Belgique Annales. 40: C177. ↩