Fluorite 43589 220043829 2008-06-18T00:50:11Z Helikophis 4470074 fixed an internal link {{Infobox mineral | name = '''Fluorite''' | category = mineral | boxwidth = | boxbgcolor = | image = Flourite.jpg | caption = Fluorite crystals on display at the [[Cullen Hall of Gems and Minerals]] | formula = [[calcium]] [[fluoride]] CaF<sub>2</sub> | molweight = | color = Colorless, white, purple, blue, blue-green, green, yellow, brownish-yellow, pink or red | habit = Occurs as well-formed coarse sized crystals also massive - granular | system = [[Cubic (crystal system)|Isometric]] 4/m bar 3 2/m | twinning = | cleavage = [111] Perfect, [111] Perfect, [111] Perfect | fracture = Uneven | mohs = 4 | luster = Vitreous | refractive = 1.433–1.435 | opticalprop = | birefringence = | pleochroism = | streak = White | gravity = 3.18 | melt = | fusibility = 3 | diagnostic = | solubility = Slightly in water | diaphaneity = | other = sometimes [[phosphorescence|phosphoresces]] when heated or scratched. Other varieties [[fluorescence|fluoresce]] }} '''Fluorite''' (also called '''fluorspar''') is a [[mineral]] composed of [[calcium fluoride]], [[Calcium|Ca]][[Fluorine|F<sub>2</sub>]]. It is an [[Cubic (crystal system)|isometric]] mineral with a cubic habit, though octahedral and more complex isometric forms are not uncommon. Cubic crystals up to 20&nbsp;cm across have been found at Dalnegorsk, Russia.<ref>''The Complete Encyclopedia of Minerals'' by P. Korbel and M. Novak</ref> [[Crystal twinning]] is common and adds complexity to the observed [[crystal]] habits. The word ''fluorite'' is derived from the [[Latin]] root ''fluo'', meaning "to flow" because the mineral has a relatively low melting point and was used as an important [[Flux (metallurgy)|flux]] in smelting. Fluorite gave its name to its constitutive element [[fluorine]]. == 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 is a widely occurring mineral which is found in large deposits in many areas. Notable deposits occur in [[Germany]], [[Austria]], [[Switzerland]], [[England]], [[Norway]], [[Mexico]], and [[Ontario]] in [[Canada]]. Large deposits also occur in Kenya in the Kerio Valley area within the Great Rift Valley. In the [[United States]] deposits are found in [[Missouri]], [[Oklahoma]], [[Illinois]], [[Kentucky]], [[Colorado]], [[New Mexico]], [[Arizona]], [[Ohio]], [[New Hampshire]], [[New York]], [[Alaska]] and [[Texas]]. [[Illinois]] has historically been the largest producer of fluorite in the United States, however, the last of the mines closed in 1995. The Illinois general assembly passed a resolution in 1965 declaring fluorite as the official [[state mineral]]. === Blue John ===<!-- This section is linked from [[Peak District]] --> [[Image:Fluorite-Vein of Blue John Cavern.JPG|thumb|left|Vein of Blue John in Treak Cliff Cavern]] One of the most famous of the older-known localities of fluorite is [[Castleton, Derbyshire|Castleton]] in [[Derbyshire]], [[England]], where, under the name of '''Derbyshire Blue John''', purple-blue fluorite was extracted from several mines/caves, including the famous [[Blue John Cavern]]. During the 19th century, this attractive fluorite was mined for its ornamental value. The name derives from French "''bleu et jaune''" (blue and yellow) characterising its color. Blue John is now scarce, and only a few hundred [[kilogram]]s are mined each year for ornamental and [[lapidary]] use. Mining still takes place in the nearby Treak Cliff Cavern. Recent deposits in China have produced fluorite with coloring and banding similar to the classic Blue John stone. == Fluorescence == [[Image:Fluorite Macro 1.JPG|200px|thumb|left|Yellow fluorite (~ 4 cm in height)]] Many samples of fluorite [[fluorescence|fluoresce]] under [[ultra-violet]] light, a property that takes its name from fluorite. Many minerals, as well as other substances, fluoresce. [[Fluorescence]] involves the elevation of electron energy levels by quanta of [[ultra-violet]] light, followed by the progressive falling back of the electrons into their previous energy state, releasing quanta of visible light in the process. In fluorite, the visible light emitted is most commonly blue, but red, purple, yellow, green and white also occur. The [[fluorescence]] of fluorite may be due to impurities such as [[yttrium]] or organic matter in the crystal lattice. It is not surprising, therefore, that the color of visible light emitted when a sample of fluorite is fluorescing appears dependent on where the original specimen was collected, different impurities having been included in the crystal lattice in different places. Neither do all fluorites fluoresce equally brightly, even from the same locality. Therefore [[ultra-violet]] light is not a reliable tool for the identification of specimens, nor for quantifying the mineral in mixtures. For example, among British fluorites, those from [[Northumberland]], [[County Durham]] and Eastern [[Cumbria]] are the most consistently fluorescent, whereas fluorites from [[Yorkshire]], [[Derbyshire]] and [[Cornwall]], if they fluoresce at all, are generally only feebly fluorescent. Fluorite also exhibits the property of [[thermoluminescence]]. == Uses == [[Image:Fluorite Galena.jpg|thumb|right|250px|Deep purple cubes of fluorite with galena (gray) and calcite (white) from Illinois, USA]] There are three principal types of industrial use for fluorite, corresponding to different grades of purity. Metallurgical grade fluorite, the lowest of the three grades, has traditionally been used as a [[Flux (metallurgy)|flux]] to lower the melting point of raw materials in [[steel]] production to aid the removal of impurities, and later in the production of [[aluminium]]. Ceramic (intermediate) grade fluorite is used in the manufacture of [[opalescence|opalescent]] [[glass]], [[vitreous enamel|enamels]] and cooking utensils. The highest grade, acid grade fluorite, is used to make [[hydrofluoric acid]] by decomposing the fluorite with [[sulfuric acid]]. Hydrofluoric acid is the primary feedstock for the manufacture of virtually all organic and inorganic fluorine-containing compounds, including [[fluoropolymer]]s and [[perfluorocarbon]]s, and is also used to etch glass. Fluorite is used instead of glass in some high performance [[Optical telescope|telescope]]s and [[camera lens]] elements. Exposure tools for the [[semiconductor]] industry make use of fluorite optical elements for [[ultraviolet light]] at 157 nm [[wavelength]]. Fluorite has a uniquely high transparency at this wavelength. Fluorite has a very low [[dispersion (optics)|dispersion]] so lenses made from it exhibit less [[chromatic aberration]] than those made of ordinary glass. In telescopes it allows crisp images of astronomical objects even at high [[optical power|power]]. Fluorite also has ornamental and [[lapidary]] uses. The Canon camera company produces synthetic fluorite crystals which are used in their more expensive telephoto lenses. ==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-ionic.png|The unit cell of fluorite's crystal structure Image:Fluorite China.jpg Image:Fluorite_with_Iron_Pyrite.jpg|Fluorite with Iron Pyrite and Calcite blooms </gallery> ==See also== * [[List of minerals]] ==References== {{Commonscat|Fluorite}} *Hurlbut, Cornelius S.; Klein, Cornelis, 1985, ''Manual of Mineralogy'', pp. 324 - 325, 20th ed., ISBN 0-471-80580-7 *[http://mineral.galleries.com/minerals/halides/fluorite/fluorite.htm Mineral Galleries] *[http://webmineral.com/data/Fluorite.shtml Webmineral] *[http://www.mindat.org/min-1576.html Mindat.org] *[http://minerals.usgs.gov/minerals/pubs/commodity/fluorspar/280499.pdf Fluorspar] <references/> ==External links== *[http://www.ukminingventures.com/WeardaleMines.htm an educational tour of Weardale Fluorite] *[http://www.isgs.uiuc.edu/servs/pubs/geobits-pub/geobit4/geobit4.htm Illinois State Geologic Survey] *[http://www.museum.state.il.us/exhibits/symbols/mineral.html Illinois state mineral] *[http://www.thebritishmuseum.ac.uk/compass/ixbin/hixclient.exe?_IXDB_=compass&_IXSR_=by6&_IXSS_=_IXFPFX_=graphical%2ffull%2f&_IXNOMATCHES_=graphical%2fno_matches%2ehtml&%24+%28with+v2_searchable_index%29+sort=%2e&_IXDB_=compass&%7bUPPER%7d%3av2_free_text_tindex=Fluorspar&_IXsearchterm=Fluorspar&_IXFIRST_=1&_IXMAXHITS_=1&_IXSPFX_=graphical/full/&_IXsearchterm=Fluorspar&submit-button=summary Barber Cup] and [http://www.thebritishmuseum.ac.uk/compass/ixbin/hixclient.exe?_IXDB_=compass&_IXSR_=by6&_IXSS_=_IXFPFX_=graphical%2ffull%2f&_IXNOMATCHES_=graphical%2fno_matches%2ehtml&%24+%28with+v2_searchable_index%29+sort=%2e&_IXDB_=compass&%7bUPPER%7d%3av2_free_text_tindex=Fluorspar&_IXsearchterm=Fluorspar&_IXFIRST_=2&_IXMAXHITS_=1&_IXSPFX_=graphical/full/&_IXsearchterm=Fluorspar&submit-button=summary Crawford Cup], related Roman cups at [[British Museum]]. *[http://wikis.lib.ncsu.edu/index.php/Fluorite/Antifluorite Fluorites and antifluorites at NCSU] *[http://www.fabreminerals.com/specimens/RSSFL-spanish-fluorite-notable-specimens.php Spanish Fluorite] [[Category:Calcium minerals]] [[Category:Halide minerals]] [[Category:Fluorine compounds]] [[ar:فلورايت]] [[ast:Fluorita]] [[be:Флюарыт]] [[bs:Fluorit]] [[br:Fluorit]] [[bg:Флуорит]] [[ca:Fluorita]] [[cs:Fluorit]] [[de:Fluorit]] [[et:Fluoriit]] [[es:Fluorita]] [[eu:Fluorita]] [[fr:Fluorine]] [[gl:Fluorita]] [[hr:Fluorit]] [[it:Fluorite]] [[he:פלואוריט]] [[lv:Fluorīts]] [[lt:Fluoritas]] [[hu:Fluorit]] [[nl:Vloeispaat]] [[ja:蛍石]] [[oc:Fluorita]] [[nds:Fluorit]] [[pl:Fluoryt]] [[pt:Fluorita]] [[ro:Fluorină]] [[ru:Флюорит]] [[sk:Fluorit]] [[sl:Fluorit]] [[fi:Fluoriitti]] [[sv:Fluorit]] [[uk:Флюорит]] [[zh-yue:螢石]] [[zh:萤石]]