Difference between revisions of "Fluorite" - New World Encyclopedia
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− | '''Fluorite''' (also called '''fluorspar''') is a [[mineral]] | + | '''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. |
The name fluorite is derived from the [[Latin]] word ''fluo'', meaning "flow," in reference to its use as a flux. | The name fluorite is derived from the [[Latin]] word ''fluo'', meaning "flow," in reference to its use as a flux. | ||
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== Occurrence == | == Occurrence == | ||
− | Fluorite may occur as a vein deposit, especially with metallic minerals, where it often forms | + | Fluorite may occur as a vein deposit, especially with metallic minerals, where it often forms part of the [[gangue]] (the worthless "host-rock" in which valuable minerals occur). 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]] | + | 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 | + | 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. |
=== Blue John === | === Blue John === | ||
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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. | ||
+ | |||
+ | Fluorite is slightly soluble in water and reacts with [[sulfuric acid]] to form hydrofluoric acid, which etches glass. | ||
=== Fluorescence === | === Fluorescence === | ||
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[[Image:Fluorite_galena09.jpg|thumb|right|250px|Deep purple cubes of fluorite with galena (gray) and calcite (white) from Illinois.]] | [[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 | + | 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 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. 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. |
==See also== | ==See also== | ||
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* [http://www.ukminingventures.com/WeardaleMines.htm Important Specimen Producing Mines in and Around Weardale.] 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 | + | * [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.museum.state.il.us/exhibits/symbols/mineral.html State Symbol: Illinois State Mineral — Fluorite] Retrieved April 9, 2007. |
Revision as of 03:47, 10 April 2007
Fluorite | |
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Cubic fluorite crystals from China |
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General | |
Category | Mineral |
Chemical formula | calcium fluoride CaF2 |
Identification | |
Color | White or colorless, purple, blue, blue-green, green, yellow, brownish-yellow, pink, or red |
Crystal habit | Occurs as well-formed coarse sized crystals also massive - granular |
Crystal system | Isometric 4/m bar 3 2/m |
Cleavage | [111] Perfect, [111] Perfect, [111] Perfect |
Fracture | Uneven |
Mohs Scale hardness | 4 |
Refractive index | 1.433-1.435 |
Streak | White |
Specific gravity | 3.18 |
{{{density}}} | |
Fusibility | 3 |
Solubility | Slightly in water |
Other Characteristics | sometimes 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.
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 (the worthless "host-rock" in which valuable minerals occur). 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.[1] Yet, 30 years later, the last of the mines in Illinois was closed down.
Blue John
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 is an 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.
Light dispersion through fluorite is very low, compared to dispersion through ordinary glass.
Fluorite is slightly soluble in water and 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 in ultraviolet 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.
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.
Uses
In addition to ornamental uses, fluorite is used in manufacturing opalescent glass, enamels, cooking utensils, hydrofluoric acid, and as a flux in the manufacture of steel. Fluorite is also used instead of glass in some high-performance telescopes and camera lens elements. Exposure tools for the semiconductor industry make use of fluorite for the optics at the wavelength of 157 nanometers (nm).[2] Fluorite is a unique material in that it 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.
See also
Notes
- ↑ D.L. Reinertsen and J.M. Masters. 2004. Fluorite—Illinois' State Mineral. Illinois State Geological Survey. Retrieved April 9, 2007.
- ↑ The wavelength of 157 nm is created by an excimer laser with F2 gas.
ReferencesISBN links support NWE through referral fees
- 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.
- Klein, Cornelis, and Barbara Dutrow. 2007. Manual of Mineral Science. 23rd ed. New York: John Wiley. ISBN 0471721573 and ISBN 978-0471721574.
- Pellant, Chris. 2002. Rocks and Minerals. Smithsonian Handbooks. New York: Dorling Kindersley. ISBN 0789491060 and ISBN 978-0789491060.
- 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. Fluorite, 'The Most Colorful Mineral in the World'. Amethyst Galleries. Retrieved April 9, 2007.
- Mindat.org. 2007. Fluorite. Mindat.org. Retrieved April 9, 2007.
External links
- Fluorite. Retrieved April 9, 2007.
- Important Specimen Producing Mines in and Around Weardale. Retrieved April 9, 2007.
- Fluorite—Illinois' State Mineral. Retrieved April 9, 2007.
- State Symbol: Illinois State Mineral — Fluorite Retrieved April 9, 2007.
- Spanish Fluorite. Retrieved April 9, 2007.
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