Thorianite is a rare

thorium Thorium is a chemical element; it has symbol Th and atomic number 90. Thorium is a weakly radioactive light silver metal which tarnishes olive grey when it is exposed to air, forming thorium dioxide; it is moderately soft, malleable, and ha ...

oxide mineral The oxide mineral class includes those minerals in which the oxide anion (O2−) is bonded to one or more metal alloys. The hydroxide-bearing minerals are typically included in the oxide class. Minerals with complex anion groups such as the sil ...

, ThO₂. It was originally described by

Ananda Coomaraswamy Ananda Kentish Muthu Coomaraswamy (, ''Āṉanta Kentiś Muthū Kumāracuvāmi''; ''Ānanda Kumārasvāmī''; 22 August 1877 − 9 September 1947) was a Ceylonese metaphysician, historian and a philosopher of Indian art who was an early inte ...

in 1904 as uraninite, but recognized as a new species by Wyndham R. Dunstan. It was so named by Dunstan on account of its high percentage of

; it also contains the oxides of

uranium Uranium is a chemical element; it has chemical symbol, symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Ura ...

lanthanum Lanthanum is a chemical element; it has symbol La and atomic number 57. It is a soft, ductile, silvery-white metal that tarnishes slowly when exposed to air. It is the eponym of the lanthanide series, a group of 15 similar elements bet ...

cerium Cerium is a chemical element; it has Chemical symbol, symbol Ce and atomic number 58. It is a hardness, soft, ductile, and silvery-white metal that tarnishes when exposed to air. Cerium is the second element in the lanthanide series, and while it ...

praseodymium Praseodymium is a chemical element; it has symbol Pr and atomic number 59. It is the third member of the lanthanide series and is considered one of the rare-earth metals. It is a soft, silvery, malleable and ductile metal, valued for its magnetic ...

and

neodymium Neodymium is a chemical element; it has Symbol (chemistry), symbol Nd and atomic number 60. It is the fourth member of the lanthanide series and is considered to be one of the rare-earth element, rare-earth metals. It is a hard (physics), hard, sli ...

Helium Helium (from ) is a chemical element; it has chemical symbol, symbol He and atomic number 2. It is a colorless, odorless, non-toxic, inert gas, inert, monatomic gas and the first in the noble gas group in the periodic table. Its boiling point is ...

is present, and the mineral is slightly less

radioactive Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is conside ...

than

pitchblende Uraninite, also known as pitchblende, is a radioactive, uranium-rich mineral and ore with a chemical composition that is largely UO2 but because of oxidation typically contains variable proportions of U3O8. Radioactive decay of the urani ...

, but is harder to shield due to its high energy gamma rays. It is common in the

alluvial Alluvium (, ) is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings. Alluvium is also sometimes called alluvial deposit. Alluvium is ...

gem-gravels of

Sri Lanka Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka, also known historically as Ceylon, is an island country in South Asia. It lies in the Indian Ocean, southwest of the Bay of Bengal, separated from the Indian subcontinent, ...

, 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 , have been reported from

Madagascar Madagascar, officially the Republic of Madagascar, is an island country that includes the island of Madagascar and numerous smaller peripheral islands. Lying off the southeastern coast of Africa, it is the world's List of islands by area, f ...

Chemistry

Based on color, specific gravity and composition three types of thorianite are distinguished: *α-thorianite *β-thorianite *γ-thorianite Thorianite and

uraninite Uraninite, also known as pitchblende, is a radioactive, uranium-rich mineral and ore with a chemical composition that is largely UO2 but because of oxidation typically contains variable proportions of U3O8. Radioactive decay of the uranium c ...

form a complete

solid solution A solid solution, a term popularly used for metals, is a homogeneous mixture of two compounds in solid state and having a single crystal structure. Many examples can be found in metallurgy, geology, and solid-state chemistry. The word "solutio ...

series in synthetic and natural material. 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%.

Rare earths The rare-earth elements (REE), also called the rare-earth metals or rare earths, and sometimes the lanthanides or lanthanoids (although scandium and yttrium, which do not belong to this series, are usually included as rare earths), are a set of ...

, chiefly

, substitute for thorium in amounts up to 8% by mass. Cerium is probably present as Ce⁴⁺. Complete series is known in synthetic material between CeO₂ - PrO₂ - ThO₂ - UO₂. Small amounts of Fe³⁺ and

zirconium Zirconium is a chemical element; it has Symbol (chemistry), symbol Zr and atomic number 40. First identified in 1789, isolated in impure form in 1824, and manufactured at scale by 1925, pure zirconium is a lustrous transition metal with a greyis ...

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. *''Uranothorianite'' *''Thorianite Cerian'' *''Thorianite La bearing''

Occurrence

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

pegmatites A pegmatite is an igneous rock showing a very coarse texture, with large interlocking crystals usually greater in size than and sometimes greater than . Most pegmatites are composed of quartz, feldspar, and mica, having a similar silicic com ...

. *Sri Lanka – In stream gravels,

Galle Galle (, ; , ) (formerly ) is a major city on the southwestern tip of Sri Lanka, south of Colombo. Galle is the provincial capital and largest city of Southern Province, Sri Lanka and is the capital of Galle District. Galle was known as ''Gi ...

district, Southern Province;

Balangoda Balangoda is a town in Ratnapura District, Sabaragamuwa Province, Sri Lanka, governed by an urban council located away from Colombo and from Ratnapura on Colombo - Batticaloa Highway(A4). It is one of the largest towns of the Sabaragamuwa Pro ...

district; near Kodrugala,

Sabaragamuwa The Sabaragamuwa Province (, , ) is one of the nine provinces of Sri Lanka. Ratnapura is the capital of the province. History The provinces of Sri Lanka were created by the British in the 19th century, but did not have any legal status until 198 ...

Province; and from a pegmatite in Bambarabotuwa area. *

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

– Reported from beach sands of

Travancore The kingdom of Travancore (), also known as the kingdom of Thiruvithamkoor () or later as Travancore State, was a kingdom that lasted from until 1949. It was ruled by the Travancore Royal Family from Padmanabhapuram, and later Thiruvanan ...

(

Kerala Kerala ( , ) is a States and union territories of India, state on the Malabar Coast of India. It was formed on 1 November 1956, following the passage of the States Reorganisation Act, by combining Malayalam-speaking regions of the erstwhile ...

). *

– Found in alluvial deposits of

Betroka Betroka is a hilly city (commune urbaine) in the Anosy Region in southern Madagascar, and is the source of the Onilahy River. It is situated at the Route nationale 13 (Madagascar), Route nationale 13, Ihosy to Tolagnaro, at 118 km from Ihosy, ...

and Andolobe. Also as very large crystals from

Fort Dauphin Fort Dauphin may refer to: ;Canada * Fort Dauphin (Manitoba), in Manitoba * Fort Dauphin (Nova Scotia), in Nova Scotia ;Haiti * Fort-Liberté Fort-Liberté (; ) is a List of communes of Haiti, commune and administrative capital of the Nord-Est ...

; at Andranondambo and other localities. *

Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...

– In black sands of a gold placer on Boshogoch River,

Transbaikalia Transbaikal, Trans-Baikal, Transbaikalia ( rus, Забайка́лье, r=Zabaykal'ye, p=zəbɐjˈkalʲjɪ), or Dauria (, ''Dauriya'') is a mountainous region to the east of or "beyond" (trans-) Lake Baikal at the south side of the eastern Si ...

Siberia Siberia ( ; , ) is an extensive geographical region comprising all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has formed a part of the sovereign territory of Russia and its predecessor states ...

; in the Kovdor Massif by

Kovdor Kovdor (, ) is a types of inhabited localities in Russia, town and the administrative center of Kovdorsky District of Murmansk Oblast, Russia, mostly known for its mining industry. Population: History By 1965, Kovdor was a urban-type settlemen ...

Kola Peninsula The Kola Peninsula (; ) is a peninsula in the extreme northwest of Russia, and one of the largest peninsulas of Europe. Constituting the bulk of the territory of Murmansk Oblast, it lies almost completely inside the Arctic Circle and is border ...

; in the

Yenisei Range The Yenisey Range () is a range of mountains in Siberia. Administratively the range is part of the Krasnoyarsk Krai of the Russian Federation. The nearest town is Severo-Yeniseysk. The mountains have granite intrusions that are associated with g ...

, Siberia. *

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

– reported from Easton,

Pennsylvania Pennsylvania, officially the Commonwealth of Pennsylvania, is a U.S. state, state spanning the Mid-Atlantic (United States), Mid-Atlantic, Northeastern United States, Northeastern, Appalachian, and Great Lakes region, Great Lakes regions o ...

; black sands in

Missouri River The Missouri River is a river in the Central United States, Central and Mountain states, Mountain West regions of the United States. The nation's longest, it rises in the eastern Centennial Mountains of the Bitterroot Range of the Rocky Moun ...

, near

Helena Helena may refer to: People *Helena (given name), a given name (including a list of people and characters with the name) *Katri Helena (born 1945), Finnish singer * Saint Helena (disambiguation), this includes places Places Greece * Helena ...

Montana Montana ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States. It is bordered by Idaho to the west, North Dakota to the east, South Dakota to the southeast, Wyoming to the south, an ...

;

Scott River The Scott River is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map accessed March 9, 2011 river in Siskiyou County, California, United States. It is a tributary of the Klamath River, one of the ...

Siskiyou County Siskiyou County ( ) is a county located in the northwestern portion of the U.S. state of California. As of the 2020 census, the population was 44,076. Its county seat is Yreka and its highest point is Mount Shasta. It falls within the Casca ...

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

; black sands in Nixon Fork and Wiseman districts,

Alaska Alaska ( ) is a non-contiguous U.S. state on the northwest extremity of North America. Part of the Western United States region, it is one of the two non-contiguous U.S. states, alongside Hawaii. Alaska is also considered to be the north ...

. *

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

– Reported with uraninite in a pegmatite on

Charlebois Lake Charlebois can refer to: People * Bob Charlebois (1944), Canadian ice hockey player * Lucie Charlebois, (1959), Canadian politician * Robert Charlebois (1944), Canadian author, actor, composer, and singer * Sylvain Charlebois (1970), Canadian rese ...

, east of

Lake Athabasca Lake Athabasca ( ; French: ''lac Athabasca''; from Woods Cree: , " herethere are plants one after another") is in the north-west corner of Saskatchewan and the north-east corner of Alberta between 58° and 60° N in Canada. The lake is ...

; Uranon variety reported from

pegmatite A pegmatite is an igneous rock showing a very coarse texture, with large interlocking crystals usually greater in size than and sometimes greater than . Most pegmatites are composed of quartz, feldspar, and mica, having a similar silicic c ...

and metesomatized zones in crystalline limestones from many locations in

Quebec Quebec is Canada's List of Canadian provinces and territories by area, largest province by area. Located in Central Canada, the province shares borders with the provinces of Ontario to the west, Newfoundland and Labrador to the northeast, ...

and

Ontario Ontario is the southernmost Provinces and territories of Canada, province of Canada. Located in Central Canada, Ontario is the Population of Canada by province and territory, country's most populous province. As of the 2021 Canadian census, it ...

. *

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

– Occurs with

baddeleyite Baddeleyite is a rare zirconium oxide mineral (ZrO2 or zirconia), occurring in a variety of monoclinic prismatic crystal forms. It is transparent to translucent, has high Index of refraction, indices of refraction, and ranges from colorless to yel ...

as an accessory in

carbonatite Carbonatite () is a type of intrusive rock, intrusive or extrusive rock, extrusive igneous rock defined by mineralogic composition consisting of greater than 50% carbonate minerals. Carbonatites may be confused with marble and may require geoche ...

Phalaborwa Phalaborwa (translated to English as ''better than the south; phala'' means ''better than and borwa'' means ''south'') is a town in the Mopani District Municipality, Limpopo province, South Africa. Name The place was called "Phalaborwa" by the S ...

Eastern Transvaal Mpumalanga () is one of the nine provinces of South Africa. The name means "East", or literally "The Place Where the Sun Rises" in the Nguni languages. Mpumalanga lies in eastern South Africa, bordering Eswatini and Mozambique. It shares bor ...

. *

Democratic Republic of Congo The Democratic Republic of the Congo (DRC), also known as the DR Congo, Congo-Kinshasa, or simply the Congo (the last ambiguously also referring to the neighbouring Republic of the Congo), is a country in Central Africa. By land area, it is t ...

Kasaï region The Kasaï region (also referred to as the Greater Kasaï region, Greater Kasaï, Grand Kasaï, or simply Kasaï) is a geographic and cultural region in south-central Democratic Republic of the Congo. Once a single province, it now comprises the ...

References

External links

{{Commons category
Uraniumminerals.com

Thorium minerals Oxide minerals Minerals described in 1904 Radioactive minerals Cubic minerals Minerals in space group 225

Chemistry

Varieties

Occurrence

See also

References

External links