Thorianite is a rare

thorium Thorium is a weakly radioactive metallic chemical element with the symbol Th and atomic number 90. Thorium is silvery and tarnishes black when it is exposed to air, forming thorium dioxide; it is moderately soft and malleable and has a high me ...

oxide mineral, ThO₂. It was originally described by

Ananda Coomaraswamy Ananda Kentish Muthu Coomaraswamy ( ta, ஆனந்த குமாரசுவாமி, ''Ānanda Kentiś Muthū Kumāraswāmī''; si, ආනන්ද කුමාරස්වාමි ''Ānanda Kumārasvāmī''; 22 August 1877 − 9 Septem ...

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 with the 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. Uranium is weak ...

lanthanum Lanthanum is a chemical element with the 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 between lant ...

cerium Cerium is a chemical element with the symbol Ce and atomic number 58. Cerium is a soft, ductile, and silvery-white metal that tarnishes when exposed to air. Cerium is the second element in the lanthanide series, and while it often shows the +3 ...

praseodymium Praseodymium is a chemical element with the symbol Pr and the atomic number 59. It is the third member of the lanthanide series and is considered to be one of the rare-earth metals. It is a soft, silvery, malleable and ductile metal, valued for i ...

and

neodymium Neodymium is a chemical element with the 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 metals. It is a hard, slightly malleable, silvery metal that quickly tarnishe ...

Helium Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. ...

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 consi ...

than

pitchblende Uraninite, formerly 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 causes t ...

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

alluvial Alluvium (from Latin ''alluvius'', from ''alluere'' 'to wash against') 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. Alluv ...

gem-gravels of

Sri Lanka Sri Lanka (, ; si, ශ්‍රී ලංකා, Śrī Laṅkā, translit-std=ISO (); ta, இலங்கை, Ilaṅkai, translit-std=ISO ()), formerly known as Ceylon and officially the Democratic Socialist Republic of Sri Lanka, is an ...

, 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 (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...

Chemistry

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

uraninite Uraninite, formerly 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 causes ...

form a complete

solid solution A solid solution, a term popularly used for metals, is a homogenous mixture of two different kinds of atoms in solid state and have a single crystal structure. Many examples can be found in metallurgy, geology, and solid-state chemistry. The wor ...

series in synthetic and natural material. 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%.

Rare earths The rare-earth elements (REE), also called the rare-earth metals or (in context) rare-earth oxides or sometimes the lanthanides (yttrium and scandium are usually included as rare earths), are a set of 17 nearly-indistinguishable lustrous silve ...

, chiefly Ce, substitute for Th in amounts up to 8% by weight. 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% 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 co ...

. *Sri Lanka – In stream gravels,

Galle Galle ( si, ගාල්ල, translit=Gālla; ta, காலி, translit=Kāli) (formerly Point de Galle) is a major city in Sri Lanka, situated on the southwestern tip, from Colombo. Galle is the provincial capital and largest city of Souther ...

district, Southern Province;

Balangoda Balangoda is a large 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 Sabaragamuw ...

district; near Kodrugala,

Sabaragamuwa The Sabaragamuwa Province ( si, සබරගමුව පළාත ''Sabaragamuwa Paḷāta'', ta, சபரகமுவ மாகாணம் ''Sabaragamuwa Mākāṇam'') is one of the nine provinces of Sri Lanka, the first level administrati ...

Province; and from a pegmatite in Bambarabotuwa area. *

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

– Reported from beach sands of

Travancore The Kingdom of Travancore ( /ˈtrævənkɔːr/), also known as the Kingdom of Thiruvithamkoor, was an Indian kingdom from c. 1729 until 1949. It was ruled by the Travancore Royal Family from Padmanabhapuram, and later Thiruvananthapuram. At ...

(

Kerala Kerala ( ; ) is a 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 regions of Cochin, Malabar, South ...

). *Madagascar – 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, Ihosy to Tolagnaro, at 118 km from Ihosy, 77 km from Isoanala and 203 km ...

and Andolobe. Also as very large crystals from Tôlanaro (Fort Dauphin); at Andranondambo and other localities. *

Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...

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

Transbaikalia Transbaikal, Trans-Baikal, Transbaikalia ( rus, Забайка́лье, r=Zabaykalye, p=zəbɐjˈkalʲjɪ), or Dauria (, ''Dauriya'') is a mountainous region to the east of or "beyond" (trans-) Lake Baikal in Far Eastern Russia. The steppe and ...

Siberia Siberia ( ; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive geographical region, constituting all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has been a part of ...

; in the Kovdor Massif by

Kovdor Kovdor (russian: Ковдор, fi, Koutero) is a 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 work settlement in the distr ...

Kola Peninsula sjd, Куэлнэгк нёа̄ррк , image_name= Kola peninsula.png , image_caption= Kola Peninsula as a part of Murmansk Oblast , image_size= 300px , image_alt= , map_image= Murmansk in Russia.svg , map_caption = Location of Murmansk Oblas ...

; in the

Yenisei Range The Yenisey Range (russian: Енисейский кряж) 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 ...

, Siberia. *

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

– reported from Easton,

Pennsylvania Pennsylvania (; ( Pennsylvania Dutch: )), officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. It borders Delaware to its southeast, ...

; black sands in Missouri River, near Helena,

Montana Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Columbi ...

;

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 in the northernmost part 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 Cascadia bioregion ...

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

; black sands in Nixon Fork and Wiseman districts,

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S., ...

. *

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

– Reported with uraninite in a pegmatite on Charlebois Lake, east of

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

; 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 com ...

and metesomatized zones in crystalline limestones from many locations in

Quebec Quebec ( ; )According to the Canadian government, ''Québec'' (with the acute accent) is the official name in Canadian French and ''Quebec'' (without the accent) is the province's official name in Canadian English is one of the thirtee ...

and

Ontario Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central Ca ...

. *

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...

– Occurs with baddeleyite as an accessory in

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

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. It is located near the confluence of the Ga-Se ...

Eastern Transvaal Mpumalanga () is a province of South Africa. The name means "East", or literally "The Place Where the Sun Rises" in the Swazi, Xhosa, Ndebele and Zulu languages. Mpumalanga lies in eastern South Africa, bordering Eswatini and Mozambique ...

. *

Democratic Republic of Congo The Democratic Republic of the Congo (french: République démocratique du Congo (RDC), colloquially "La RDC" ), informally Congo-Kinshasa, DR Congo, the DRC, the DROC, or the Congo, and formerly and also colloquially Zaire, is a country in ...

Kasaï region The Kasai region is a region in the central southern part of the Democratic Republic of the Congo. It shares its name with the Kasai River. After the independence of Congo in 1960, Kasai seceded for a while under influence of Belgium and became a ...

References

External links

{{Commons category
Uraniumminerals.com

Thorium minerals Oxide minerals Uranium minerals Lanthanide minerals Radioactive minerals Cubic minerals Minerals in space group 225

Chemistry

Varieties

Occurrence

See also

References

External links