Thorite: Difference between revisions
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'''Thorite''', (Th,U)SiO<sub>4</sub>, is a rare [[Silicate minerals|nesosilicate]] of [[thorium]] that [[crystal]]lizes in the tetragonal system and is isomorphous with [[zircon]]. It is the most common [[mineral]] of [[thorium]] and is nearly always strongly [[Radioactivity|radioactive]]. It was named in 1829 to reflect its [[thorium]] content. |
'''Thorite''', (Th,U)SiO<sub>4</sub>, is a rare [[Silicate minerals|nesosilicate]] of [[thorium]] that [[crystal]]lizes in the tetragonal system and is isomorphous with [[zircon]]. It is the most common [[mineral]] of [[thorium]] and is nearly always strongly [[Radioactivity|radioactive]]. It was named in 1829 to reflect its [[thorium]] content. Thorite was discovered in 1828 on the island of Løvø, Norway, by the vicar and mineralogist, [[Morten Thrane Esmark|Hans Morten Thrane Esmark]], who sent the first specimens of this black mineral to his father, [[Jens Esmark]], who was a professor of geology. |
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[[File:Thorit 1.jpg|thumb|300px|Thorite in Prague national museum]] |
[[File:Thorit 1.jpg|thumb|300px|Thorite in Prague national museum]] |
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Specimens of thorite generally come from [[igneous rock|igneous]] [[pegmatite]]s and [[volcanic]] extrusive rocks, hydrothermal veins and contact [[metamorphic rock]]s. It is also known to occur as small grains in detrital sands. Crystals are rare, but when found can produce nicely shaped short prismatic crystals with pyramidal terminations. |
Specimens of thorite generally come from [[igneous rock|igneous]] [[pegmatite]]s and [[volcanic]] extrusive rocks, hydrothermal veins and contact [[metamorphic rock]]s. It is also known to occur as small grains in detrital sands. Crystals are rare, but when found can produce nicely shaped short prismatic crystals with pyramidal terminations. |
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Revision as of 21:11, 31 October 2010
Thorite, (Th,U)SiO4, is a rare nesosilicate of thorium that crystallizes in the tetragonal system and is isomorphous with zircon. It is the most common mineral of thorium and is nearly always strongly radioactive. It was named in 1829 to reflect its thorium content. Thorite was discovered in 1828 on the island of Løvø, Norway, by the vicar and mineralogist, Hans Morten Thrane Esmark, who sent the first specimens of this black mineral to his father, Jens Esmark, who was a professor of geology.
Specimens of thorite generally come from igneous pegmatites and volcanic extrusive rocks, hydrothermal veins and contact metamorphic rocks. It is also known to occur as small grains in detrital sands. Crystals are rare, but when found can produce nicely shaped short prismatic crystals with pyramidal terminations.
Thorite is currently an important ore of uranium. A variety of thorite, often called "uranothorite", is particularly rich in uranium and has been a viable uranium ore at Bancroft in Ontario, Canada. Other varieties of thorite include "orangite", an orange variety, and "calciothorite", an impure variety with trace amounts of calcium.
Thorite is commonly metamict and hydrated, making it optically isotropic and amorphous. Owing to differences in composition, the specific gravity varies from 4.4 to 6.6 g/cm3. Hardness is 4.5 and the luster is vitreous or resinous. The color is normally black, but also brownish black, orange, yellowish-orange and dark green.
Because thorite is highly radioactive, specimens are often metamict. This is a condition found in radioactive minerals that results from the destructive effects of its own radiation on its crystal lattice. The effect can destroy a crystal lattice completely while leaving the outward appearance unchanged.
References
 | This article about a specific silicate mineral is a stub. You can help Wikipedia by expanding it. |
Chisholm, Hugh, ed. (1911). Encyclopædia Britannica (11th ed.). Cambridge University Press. {{cite encyclopedia}}: Missing or empty |title= (help)This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). Encyclopædia Britannica (11th ed.). Cambridge University Press. {{cite encyclopedia}}: Missing or empty |title= (help)
