Difference between revisions of "Fluorite" - New World Encyclopedia

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{{Infobox mineral
 
{{Infobox mineral
| name       = Fluorite
+
| name   = Fluorite
| category   =  
+
| category =  
| boxwidth   =  
+
| boxwidth =  
| boxbgcolor =  
+
| boxbgcolor =  
| image       = Fluorite China.jpg
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| image   = Fluorite China.jpg
| caption     = Cubic fluorite crystals from China
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| caption   = Cubic fluorite crystals from China
| formula     = [[calcium]] [[fluoride]] CaF<sub>2</sub>
+
| formula   = [[calcium]] [[fluoride]] CaF<sub>2</sub>
| molweight   =  
+
| molweight =  
| color       = White or colorless, purple, blue, blue-green, green, yellow, brownish-yellow, pink, or red
+
| color   = White or colorless, purple, blue, blue-green, green, yellow, brownish-yellow, pink, or red
| habit       = Occurs as well-formed coarse sized crystals also massive - granular
+
| habit   = Occurs as well-formed coarse sized crystals also massive - granular
| system     = [[Cubic (crystal system)|Isometric]] 4/m bar 3 2/m
+
| system   = [[Cubic (crystal system)|Isometric]] 4/m bar 3 2/m
| twinning   =  
+
| twinning =  
| cleavage   = [111] Perfect, [111] Perfect, [111] Perfect
+
| cleavage = [111] Perfect, [111] Perfect, [111] Perfect
| fracture   = Uneven
+
| fracture = Uneven
| mohs       = 4
+
| mohs   = 4
| luster     =  
+
| luster   =  
| refractive = 1.433-1.435
+
| refractive = 1.433-1.435
 
| opticalprop =  
 
| opticalprop =  
 
| birefringence =  
 
| birefringence =  
 
| pleochroism =  
 
| pleochroism =  
| streak     = White
+
| streak   = White
| gravity     = 3.18
+
| gravity   = 3.18
| melt       =  
+
| density  =
| fusibility = 3
+
| melt   =  
| diagnostic =  
+
| fusibility = 3
| solubility = Slightly in water
+
| diagnostic =  
 +
| solubility = Slightly in water
 
| diaphaneity =  
 
| diaphaneity =  
| other       = sometimes [[phosphorescence|phosphoresces]] when heated or scratched. Other varieties [[fluorescence|fluoresce]] beautifully
+
| other   = sometimes [[phosphorescence|phosphoresces]] when heated or scratched. Other varieties [[fluorescence|fluoresce]] beautifully
 
}}
 
}}
  
'''Fluorite''' (also called '''fluorspar''') is a [[mineral]] found in large deposits in many parts of the world. Chemically, it is composed of [[calcium fluoride]] (chemical formula CaF<sub>2</sub>).
+
'''Fluorite''' (also called ''fluorspar'') is a [[mineral]] composed of [[calcium fluoride]] (chemical formula CaF<sub>2</sub>). It is present in large deposits in many parts of the world and occurs in a wide variety of colors, including blue, purple, red, yellow, green, and white. Fluorite gives its name to the property of [[fluorescence]], as many (but not all) samples of this mineral produce a strong glow when exposed to [[ultraviolet]] [[light]].
 
+
{{toc}}
The name fluorite is derived from the [[Latin]] word ''fluo'', meaning "flow," in reference to its use as a flux.
+
Historically, some varieties of fluorite have been used for ornamental purposes. Currently, it is used in manufacturing [[opalescence|opalescent]] [[glass]], [[vitreous enamel|enamels]], cooking utensils, and hydrofluoric [[acid]]. In addition, it is used instead of glass in some high-performance telescopes and [[camera lens]]es. It is also a [[Flux (metallurgy)|flux]] in the manufacture of [[steel]]. The name fluorite is derived from the [[Latin]] word ''fluo'', meaning "flow," in reference to its use as a flux.
  
 
== Occurrence ==
 
== Occurrence ==
  
Fluorite may occur as a vein deposit, especially with metallic minerals, where it often forms a part of the [[gangue]] (the worthless "host-rock" in which valuable minerals occur) and may be associated with [[galena]], [[sphalerite]], [[barite]], [[quartz]], and [[calcite]]. It is a common mineral in deposits of [[hydrothermal]] origin and has been noted as a primary mineral in [[granite]]s and other [[igneous rock]]s and as a common minor constituent of [[dolostone]] and [[limestone]].
+
Fluorite may occur as a vein deposit, especially with metallic minerals, where it often forms part of the [[gangue]].<ref>Gangue is the worthless "host-rock" in which valuable minerals occur.</ref> It may be found associated with minerals such as [[galena]], [[sphalerite]], [[barite]], [[quartz]], and [[calcite]]. It is a common mineral in deposits of [[hydrothermal]] origin and has been noted as a primary mineral in [[granite]]s and other [[igneous rock]]s. It is a common minor constituent of [[dolostone]] and [[limestone]].
  
Fluorite is widely distributed around the world. Notable deposits occur in [[Germany]], [[Austria]], [[Switzerland]], [[England]], [[Norway]], [[Mexico]], and [[Ontario]] in [[Canada]]. In the [[United States]], deposits are found in [[Missouri]], [[Oklahoma]], [[Illinois]], [[Kentucky]], [[Colorado]], [[New Mexico]], [[Arizona]], [[Ohio]], [[New Hampshire]], [[New York]], and [[Texas]].
+
Fluorite is widely distributed around the world. Notable deposits occur in [[Germany]], [[Austria]], [[Switzerland]], [[England]], [[Norway]], [[Mexico]], and [[Ontario]], [[Canada]]. In the [[United States]], deposits are found in [[Missouri]], [[Oklahoma]], [[Illinois]], [[Kentucky]], [[Colorado]], [[New Mexico]], [[Arizona]], [[Ohio]], [[New Hampshire]], [[New York]], and [[Texas]].
  
 
=== Illinois ===
 
=== Illinois ===
  
The State of Illinois has historically been the largest producer of fluorite in the United States. In 1965, the Illinois General Assembly passed a resolution declaring fluorite the official state mineral.<ref>D.L. Reinertsen and J.M. Masters. 2004. [http://www.isgs.uiuc.edu/servs/pubs/geobits-pub/geobit4/geobit4.htm Fluorite—Illinois' State Mineral.] ''Illinois State Geological Survey''. Retrieved April 9, 2007.</ref> Yet, 30 years later, the last of the mines in Illinois was closed down.
+
The State of Illinois has historically been the largest producer of fluorite in the United States. In 1965, the Illinois General Assembly passed a resolution declaring fluorite the official state mineral. Yet, 30 years later, the last of the mines in Illinois was closed down.
  
 
=== Blue John ===
 
=== Blue John ===
[[Image:Blue_John_Veins_in_the_Blue_John_Cavern.jpg|left|thumb|180px|Blue John veins in the Blue John Cavern, United Kingdom.]]
+
[[Image:Blue_John_Veins_in_the_Blue_John_Cavern.jpg|right|thumb|200px|Fluorite veins in the Blue John Cavern, United Kingdom.]]
  
One of the most famous sites for the excavation of fluorite has been the [[Blue John Cavern]] in [[Castleton]], [[Derbyshire]], [[England]]. This site has yielded beautiful, purple-blue fluorite, under the name '''Derbyshire Blue John''', which was used for ornamental purposes, especially in the nineteenth century. The name "Blue John" derives from the French words "''bleu et jaune''" (blue and yellow), characterizing its colors. This site is now depleted, and only a few hundred [[kilogram]]s (kg) are mined each year for ornamental and [[lapidary]] use. Recently, deposits in China have produced fluorite with similar coloring and banding to the classic Blue John stone.
+
One of the most famous sites for the excavation of fluorite has been the [[Blue John Cavern]] in [[Castleton]], [[Derbyshire]], [[England]]. This site has yielded beautiful, purple-blue fluorite, under the name ''Derbyshire Blue John'', which was used for ornamental purposes, especially in the nineteenth century. The name "Blue John" derives from the French words "''bleu et jaune''" (blue and yellow), characterizing its colors. This site is now depleted, and only a few hundred [[kilogram]]s (kg) are mined each year for ornamental and [[lapidary]] use. Recently, deposits in [[China]] have produced fluorite with similar coloring and banding to the classic Blue John stone.
  
 
== Characteristics ==
 
== Characteristics ==
  
Fluorite is an [[Cubic (crystal system)|isometric]] mineral with a cubic habit, though octahedral and more complex isometric forms are not uncommon. [[Crystal twinning]] is common and adds complexity to the observed [[crystal]] habits.
+
Fluorite [[crystal]]s are [[Cubic (crystal system)|isometric]] with a cubic habit, though octahedral and more complex isometric forms are not uncommon. [[Crystal twinning]] is common and adds complexity to the observed crystal habits. Light dispersion through fluorite is very low, compared to dispersion through ordinary glass.
  
Light dispersion through fluorite is very low, compared to dispersion through ordinary glass.
+
This mineral is slightly [[solubility|soluble]] in water. It reacts with [[sulfuric acid]] to form hydrofluoric acid, which etches glass.
  
 
=== Fluorescence ===
 
=== Fluorescence ===
  
Fluorite gives its name to the property of [[fluorescence]], as many samples fluoresce strongly in [[ultraviolet]] light. The fluorescence may be due to impurities such as [[yttrium]] or organic matter in the crystal lattice.
+
Fluorite gives its name to the property of [[fluorescence]], as many samples fluoresce strongly when exposed to [[ultraviolet]] (UV) light. The fluorescence may be due to impurities such as [[yttrium]] or [[organic]] matter in the crystal lattice.
  
Yet, not all fluorites fluoresce, even from the same locality, so UV lighting is not a reliable tool for identification of specimens, or for quantifying the mineral in mixtures. For example, among British fluorites, those from Northumberland, Durham and Eastern Cumbria are the most consistently fluorescent. Those from Yorkshire, Derbyshire and Cornwall are generally either not fluorescent, or feebly fluorescent.
+
Yet, not all fluorites fluoresce, even if obtained from the same locality. For this reason, UV lighting is not a reliable tool for identifying specimens or quantifying the mineral in mixtures. For example, among British fluorites, those from Northumberland, Durham, and Eastern Cumbria are the most consistently fluorescent. Those from Yorkshire, Derbyshire, and Cornwall are generally either feebly fluorescent or not fluorescent at all.
  
Fluorite's fluorescence color is largely dependent on where the original specimen was located. Blue is the most common color but red, purple, yellow, green and white also occur. Fluorite also exhibits the property of [[thermoluminescence]].
+
The fluorescent color of fluorite is largely dependent on where the original specimen was located. Blue is the most common color, but red, purple, yellow, green and white also occur. Fluorite also exhibits the property of [[thermoluminescence]].
  
 
== Uses ==
 
== Uses ==
[[Image:Fluorite_galena09.jpg|thumb|right|250px|Deep purple cubes of fluorite with galena (gray) and calcite (white) from Illinois.]]
 
  
In addition to ornamental uses, fluorite is used in manufacturing [[opalescence|opalescent]] [[glass]], [[vitreous enamel|enamels]], cooking utensils, [[hydrofluoric acid]], and as a [[Flux (metallurgy)|flux]] in the manufacture of [[steel]]. Fluorite is also used instead of glass in some high-performance [[telescope]]s and [[camera lens]] elements. Exposure tools for the [[semiconductor]] industry make use of fluorite for the optics for 157 nm wavelength. This wavelength is created by an [[excimer laser]] with F<sub>2</sub> gas, and the fluorite is a unique material that has high transparency at this wavelength. Given the low dispersion of light through fluorite, this mineral is used in telescopes to produce crisp images of astronomical objects even at high power. Fluorite is slightly soluble in water, and reacts with [[sulfuric acid]] to form hydrofluoric acid, which etches glass.
+
As noted above, fluorite comes in various colors and has been used for ornamental purposes. In addition, it is used in manufacturing [[opalescence|opalescent]] [[glass]], [[vitreous enamel|enamels]], cooking utensils, [[hydrofluoric acid]], and as a [[Flux (metallurgy)|flux]] in the manufacture of [[steel]].
 +
 
 +
Given the low dispersion of light through fluorite, this mineral is used instead of glass in high-performance telescopes to produce crisp images of [[astronomy|astronomical]] objects even at high power. Likewise, it is used in [[camera lens]] elements. Exposure tools for the [[semiconductor]] industry make use of fluorite for optics at the wavelength of 157 nanometers (nm).<ref>The wavelength of 157 nm is created by an [[excimer laser]] with F<sub>2</sub> gas.</ref> Fluorite is a unique material in that it has high transparency at this wavelength.
  
 
==See also==
 
==See also==
Line 75: Line 77:
 
* [[Mineral]]
 
* [[Mineral]]
 
* [[Quartz]]
 
* [[Quartz]]
 +
 +
==Gallery==
 +
<gallery>
 +
Image:pig.fluorite.750pix.jpg|Pig carved in fluorite, 5 cm (2 inches) long
 +
Image:USDA Mineral Flourite 93c3962.jpg|Mineral fluorite
 +
Image:Fluorite USA.jpg|Octahedral fluorite crystals from New Mexico, USA
 +
image:Fluorite_crystals_270x444.jpg|Cleaved fluorite octahedra
 +
Image:Fluorite-unit-cell-3D.png|The unit cell of fluorite's crystal structure
 +
</gallery>
  
 
== Notes ==
 
== Notes ==
Line 81: Line 92:
 
==References==
 
==References==
  
* Farndon, John. 2006. ''The Practical Encyclopedia of Rocks & Minerals: How to Find, Identify, Collect and Maintain the World's best Specimens, with over 1000 Photographs and Artworks''. London: Lorenz Books. ISBN 0754815412 and ISBN 978-0754815419.
+
* Farndon, John. ''The Practical Encyclopedia of Rocks & Minerals: How to Find, Identify, Collect and Maintain the World's best Specimens, with over 1000 Photographs and Artworks''. London: Lorenz Books, 2006. ISBN 0754815412
 
+
* Klein, Cornelis, and Barbara Dutrow. ''Manual of Mineral Science''. 23rd ed. New York: John Wiley, 2007. ISBN 0471721573
* Klein, Cornelis, and Barbara Dutrow. 2007. ''Manual of Mineral Science''. 23rd ed. New York: John Wiley. ISBN 0471721573 and ISBN 978-0471721574.
+
* Pellant, Chris. ''Rocks and Minerals''. Smithsonian Handbooks. New York: Dorling Kindersley, 2002. ISBN 0789491060
 
+
* Shaffer, Paul R., Herbert S. Zim, and Raymond Perlman. ''Rocks, Gems and Minerals''. Rev. ed. New York: St. Martin's Press, 2001. ISBN 1582381321
* Pellant, Chris. 2002. ''Rocks and Minerals''. Smithsonian Handbooks. New York: Dorling Kindersley. ISBN 0789491060 and ISBN 978-0789491060.
+
* Mindat.org. [http://www.mindat.org/min-1576.html Fluorite.] ''Mindat.org''. 2007. Retrieved September 4, 2022.
 
 
* Shaffer, Paul R., Herbert S. Zim, and Raymond Perlman. 2001. ''Rocks, Gems and Minerals''. Rev. ed. New York: St. Martin's Press. ISBN 1582381321 and ISBN 978-1582381329.
 
 
 
* Mineral Gallery. 2006. [http://mineral.galleries.com/minerals/halides/fluorite/fluorite.htm Fluorite, 'The Most Colorful Mineral in the World'.] ''Amethyst Galleries''. Retrieved April 9, 2007.
 
 
 
* Mindat.org. 2007. [http://www.mindat.org/min-1576.html Fluorite.] ''Mindat.org''. Retrieved April 9, 2007.
 
  
 
==External links==
 
==External links==
 +
All links retrieved April 17, 2017.
 +
* [http://webmineral.com/data/Fluorite.shtml Fluorite]
 +
* [http://www.museum.state.il.us/exhibits/symbols/mineral.html State Symbol: Illinois State Mineral—Fluorite]
 +
*[http://www.fabreminerals.com/specimens/RSSFL-spanish-fluorite-notable-specimens.php Spanish Fluorite]
  
* [http://webmineral.com/data/Fluorite.shtml Fluorite.] Retrieved April 9, 2007.
 
 
* [http://www.ukminingventures.com/WeardaleMines.htm Important Specimen Producing Mines in and Around Weardale.] Retrieved April 9, 2007.
 
 
* [http://www.isgs.uiuc.edu/servs/pubs/geobits-pub/geobit4/geobit4.htm Fluorite—Illinois' State Mineral.] Retrieved April 9, 2007.
 
 
* [http://www.museum.state.il.us/exhibits/symbols/mineral.html State Symbol: Illinois State Mineral — Fluorite] Retrieved April 9, 2007.
 
 
*[http://www.fabreminerals.com/specimens/RSSFL-spanish-fluorite-notable-specimens.php Spanish Fluorite.] Retrieved April 9, 2007.
 
 
==Gallery==
 
<gallery>
 
Image:pig.fluorite.750pix.jpg|Pig carved in fluorite, 5 cm (2 inches) long
 
Image:USDA Mineral Flourite 93c3962.jpg|Mineral fluorite
 
Image:Fluorite USA.jpg|Octahedral fluorite crystals from New Mexico, USA
 
image:Fluorite_crystals_270x444.jpg|Cleaved fluorite octahedra
 
Image:Fluorite-unit-cell-3D.png|The unit cell of fluorite's crystal structure
 
</gallery>
 
  
 
[[Category:Physical sciences]]
 
[[Category:Physical sciences]]

Revision as of 04:42, 4 September 2022

Fluorite
Fluorite China.jpg
Cubic fluorite crystals from China
General
CategoryMineral
Chemical formulacalcium fluoride CaF2
Identification
ColorWhite or colorless, purple, blue, blue-green, green, yellow, brownish-yellow, pink, or red
Crystal habitOccurs as well-formed coarse sized crystals also massive - granular
Crystal systemIsometric 4/m bar 3 2/m
Cleavage[111] Perfect, [111] Perfect, [111] Perfect
FractureUneven
Mohs Scale hardness4
Refractive index1.433-1.435
StreakWhite
Specific gravity3.18
Fusibility3
SolubilitySlightly in water
Other Characteristicssometimes phosphoresces when heated or scratched. Other varieties fluoresce beautifully

Fluorite (also called fluorspar) is a mineral composed of calcium fluoride (chemical formula CaF2). It is present in large deposits in many parts of the world and occurs in a wide variety of colors, including blue, purple, red, yellow, green, and white. Fluorite gives its name to the property of fluorescence, as many (but not all) samples of this mineral produce a strong glow when exposed to ultraviolet light.

Historically, some varieties of fluorite have been used for ornamental purposes. Currently, it is used in manufacturing opalescent glass, enamels, cooking utensils, and hydrofluoric acid. In addition, it is used instead of glass in some high-performance telescopes and camera lenses. It is also a flux in the manufacture of steel. The name fluorite is derived from the Latin word fluo, meaning "flow," in reference to its use as a flux.

Occurrence

Fluorite may occur as a vein deposit, especially with metallic minerals, where it often forms part of the gangue.[1] It may be found associated with minerals such as galena, sphalerite, barite, quartz, and calcite. It is a common mineral in deposits of hydrothermal origin and has been noted as a primary mineral in granites and other igneous rocks. It is a common minor constituent of dolostone and limestone.

Fluorite is widely distributed around the world. Notable deposits occur in Germany, Austria, Switzerland, England, Norway, Mexico, and Ontario, Canada. In the United States, deposits are found in Missouri, Oklahoma, Illinois, Kentucky, Colorado, New Mexico, Arizona, Ohio, New Hampshire, New York, and Texas.

Illinois

The State of Illinois has historically been the largest producer of fluorite in the United States. In 1965, the Illinois General Assembly passed a resolution declaring fluorite the official state mineral. Yet, 30 years later, the last of the mines in Illinois was closed down.

Blue John

Fluorite veins in the Blue John Cavern, United Kingdom.

One of the most famous sites for the excavation of fluorite has been the Blue John Cavern in Castleton, Derbyshire, England. This site has yielded beautiful, purple-blue fluorite, under the name Derbyshire Blue John, which was used for ornamental purposes, especially in the nineteenth century. The name "Blue John" derives from the French words "bleu et jaune" (blue and yellow), characterizing its colors. This site is now depleted, and only a few hundred kilograms (kg) are mined each year for ornamental and lapidary use. Recently, deposits in China have produced fluorite with similar coloring and banding to the classic Blue John stone.

Characteristics

Fluorite crystals are isometric with a cubic habit, though octahedral and more complex isometric forms are not uncommon. Crystal twinning is common and adds complexity to the observed crystal habits. Light dispersion through fluorite is very low, compared to dispersion through ordinary glass.

This mineral is slightly soluble in water. It reacts with sulfuric acid to form hydrofluoric acid, which etches glass.

Fluorescence

Fluorite gives its name to the property of fluorescence, as many samples fluoresce strongly when exposed to ultraviolet (UV) light. The fluorescence may be due to impurities such as yttrium or organic matter in the crystal lattice.

Yet, not all fluorites fluoresce, even if obtained from the same locality. For this reason, UV lighting is not a reliable tool for identifying specimens or quantifying the mineral in mixtures. For example, among British fluorites, those from Northumberland, Durham, and Eastern Cumbria are the most consistently fluorescent. Those from Yorkshire, Derbyshire, and Cornwall are generally either feebly fluorescent or not fluorescent at all.

The fluorescent color of fluorite is largely dependent on where the original specimen was located. Blue is the most common color, but red, purple, yellow, green and white also occur. Fluorite also exhibits the property of thermoluminescence.

Uses

As noted above, fluorite comes in various colors and has been used for ornamental purposes. In addition, it is used in manufacturing opalescent glass, enamels, cooking utensils, hydrofluoric acid, and as a flux in the manufacture of steel.

Given the low dispersion of light through fluorite, this mineral is used instead of glass in high-performance telescopes to produce crisp images of astronomical objects even at high power. Likewise, it is used in camera lens elements. Exposure tools for the semiconductor industry make use of fluorite for optics at the wavelength of 157 nanometers (nm).[2] Fluorite is a unique material in that it has high transparency at this wavelength.

See also

Gallery

Notes

  1. Gangue is the worthless "host-rock" in which valuable minerals occur.
  2. The wavelength of 157 nm is created by an excimer laser with F2 gas.

References
ISBN links support NWE through referral fees

  • Farndon, John. The Practical Encyclopedia of Rocks & Minerals: How to Find, Identify, Collect and Maintain the World's best Specimens, with over 1000 Photographs and Artworks. London: Lorenz Books, 2006. ISBN 0754815412
  • Klein, Cornelis, and Barbara Dutrow. Manual of Mineral Science. 23rd ed. New York: John Wiley, 2007. ISBN 0471721573
  • Pellant, Chris. Rocks and Minerals. Smithsonian Handbooks. New York: Dorling Kindersley, 2002. ISBN 0789491060
  • Shaffer, Paul R., Herbert S. Zim, and Raymond Perlman. Rocks, Gems and Minerals. Rev. ed. New York: St. Martin's Press, 2001. ISBN 1582381321
  • Mindat.org. Fluorite. Mindat.org. 2007. Retrieved September 4, 2022.

External links

All links retrieved April 17, 2017.

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