Editing Fluorescence (section)

==== Gemology, mineralogy and geology ====
[[File:Aragonit - Fluorescence.gif|thumb|left|Fluorescence of [[aragonite]]]]
[[File:Rough diamonds - necklace in UV and normal light B - composite.jpg|thumb|left|Necklace of rough diamonds under [[Blacklight|UV light]] (top) and normal light (bottom)]]
In addition to the eponymous [[fluorspar]],<ref>Raman, C.V., (1962). [https://www.currentscience.ac.in/Volumes/31/09/0361.pdf "The luminescence of fluorspar"], Curr. Sci., 31, 361–365</ref> many
[[gemstone]]s and [[mineral]]s may have a distinctive fluorescence or may fluoresce differently under short-wave ultraviolet, long-wave ultraviolet, visible light, or [[X-ray]]s.

Many types of [[calcite]] and [[amber]] will fluoresce under shortwave UV, longwave UV and visible light. [[Ruby|Rubies]], [[emerald]]s, and [[diamond]]s exhibit red fluorescence under long-wave UV, blue and sometimes green light; diamonds also emit light under [[X-ray]] radiation.

Fluorescence in minerals is caused by a wide range of [[Activator (phosphor)|activators]]. In some cases, the concentration of the activator must be restricted to below a certain level, to prevent quenching of the fluorescent emission. Furthermore, the mineral must be free of impurities such as [[iron]] or [[copper]], to prevent quenching of possible fluorescence. Divalent [[manganese]], in concentrations of up to several percent, is responsible for the red or orange fluorescence of [[calcite]], the green fluorescence of [[willemite]], the yellow fluorescence of [[esperite]], and the orange fluorescence of [[wollastonite]] and [[clinohedrite]]. Hexavalent [[uranium]], in the form of the [[uranyl cation]] ({{chem|UO|2|2+}}), fluoresces at all concentrations in a yellow green, and is the cause of fluorescence of minerals such as [[autunite]] or [[andersonite]], and, at low concentration, is the cause of the fluorescence of such materials as some samples of [[hyalite]] [[opal]]. Trivalent [[chromium]] at low concentration is the source of the red fluorescence of [[ruby]]. Divalent [[europium]] is the source of the blue fluorescence, when seen in the mineral [[fluorite]]. Trivalent [[lanthanide]]s such as [[terbium]] and [[dysprosium]] are the principal activators of the creamy yellow fluorescence exhibited by the [[yttrofluorite]] variety of the mineral fluorite, and contribute to the orange fluorescence of [[zircon]]. [[Powellite]] ([[calcium molybdate]]) and [[scheelite]] (calcium tungstate) fluoresce intrinsically in yellow and blue, respectively. When present together in [[solid solution]], energy is transferred from the higher-energy [[tungsten]] to the lower-energy [[molybdenum]], such that fairly low levels of [[molybdenum]] are sufficient to cause a yellow emission for [[scheelite]], instead of blue. Low-iron [[sphalerite]] (zinc sulfide), fluoresces and phosphoresces in a range of colors, influenced by the presence of various trace impurities.

Crude oil ([[petroleum]]) fluoresces in a range of colors, from dull-brown for heavy oils and tars through to bright-yellowish and bluish-white for very light oils and condensates. This phenomenon is used in [[oil exploration]] drilling to identify very small amounts of oil in drill cuttings and core samples.

[[Humic acid]]s and [[fulvic acid]]s produced by the degradation of [[organic matter]] in soils ([[humus]]) may also fluoresce because of the presence of aromatic cycles in their complex [[molecular structure]]s.<ref name="Mobed_1966">{{Cite journal| doi = 10.1021/es960132l| issn = 0013-936X| volume = 30| issue = 10| pages = 3061–3065| last1 = Mobed| first1 = Jarafshan J.| last2 = Hemmingsen| first2 = Sherry L.| last3 = Autry| first3 = Jennifer L.| last4 = McGown| first4 = Linda B.| title = Fluorescence characterization of IHSS humic substances: Total luminescence spectra with absorbance correction| journal = Environmental Science & Technology| accessdate = 2021-08-29| date = 1996-09-01| bibcode = 1996EnST...30.3061M| url = https://doi.org/10.1021/es960132l| archive-date = 4 May 2022| archive-url = https://web.archive.org/web/20220504144922/https://pubs.acs.org/doi/10.1021/es960132l| url-status = live}}</ref> Humic substances dissolved in [[groundwater]] can be detected and characterized by [[spectrofluorimetry]].<ref name="Milori_2002">{{Cite journal| issn = 0038-075X| volume = 167| issue = 11| pages = 739–749| last1 = Milori| first1 = Débora MBP| last2 = Martin-Neto| first2 = Ladislau| last3 = Bayer| first3 = Cimélio| last4 = Mielniczuk| first4 = João| last5 = Bagnato| first5 = Vanderlei S| title = Humification degree of soil humic acids determined by fluorescence spectroscopy| journal = Soil Science| date = 2002| doi = 10.1097/00010694-200211000-00004| bibcode = 2002SoilS.167..739M| s2cid = 98552138}}</ref>
<ref name="Richard_2004">{{Cite journal| issn = 0013-936X| volume = 38| issue = 7| pages = 2052–2057| last1 = Richard| first1 = C| last2 = Trubetskaya| first2 = O| last3 = Trubetskoj| first3 = O| last4 = Reznikova| first4 = O| last5 = Afanas' Eva| first5 = G| last6 = Aguer| first6 = J-P| last7 = Guyot| first7 = G| title = Key role of the low molecular size fraction of soil humic acids for fluorescence and photoinductive activity| journal = Environmental Science & Technology| date = 2004| doi = 10.1021/es030049f| pmid = 15112806| bibcode = 2004EnST...38.2052R}}</ref>
<ref name="Sierra_2005">{{Cite journal| issn = 0045-6535| volume = 58| issue = 6| pages = 715–733| last1 = Sierra| first1 = MMD| last2 = Giovanela| first2 = M| last3 = Parlanti| first3 = E| last4 = Soriano-Sierra| first4 = EJ| title = Fluorescence fingerprint of fulvic and humic acids from varied origins as viewed by single-scan and excitation/emission matrix techniques| journal = Chemosphere| date = 2005| doi = 10.1016/j.chemosphere.2004.09.038| pmid = 15621185| bibcode = 2005Chmsp..58..715S}}</ref>