Difference between revisions of "Fluorescent minerals"

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[[File:21.1213-CR2071-d1.jpg|thumb|]]
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[[File:Fluorescent-minerals.jpg|thumb|Fluorescent minerals]]
 
== Description ==
 
== Description ==
  
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A family of minerals composed of trisilicates with [[aluminum]], [[iron]], [[calcium]], [[magnesium]], [[manganese]], or [[chromium]]. Garnets are found in deposits around the world as transparent crystals embedded in igneous and metamorphic rocks. They have been used as gemstones since antiquity. The ruby red [[pyrope]] and the lighter red [[almandine]] were the most highly prized varieties. The pale rose-purple [[rhodolite]] is a mixture of pyrope and almandine. Garnets are also used as abrasives. The crushed, ground and cleaned garnet is sold as an abrasive powder, coated paper and coated cloth. Garnet particles have sharper cutting edges than aluminum oxide, but are expensive. To decrease costs, some commercially available garnet cloths are actually prepared with quartz. Sources of gem quality garnets include the Czech Republic, South Africa, Australia, China, India, Brazil, Sri Lanka, and the U.S (New York, Maine, Idaho).
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Minerals that have the unique physical property to absorb light and one wavelength and instantaneously release it at a different wavelength, resulting in a temporary color change to the eye of the human observer. Only about 15% of minerals are able to fluoresce. The fluorescence is usually due to a cation activator, such as: tungsten, molybdenum, lead, boron, titanium, manganese, uranium, and chromium, but some rare earth elements are also able to contribute to the phenomenon. Some trace elements, such as iron or copper, can quench the fluorscence. Most minerals fluoresce a single color, but some may have multiple colors; for example calcite can fluoresce red, blue, white, pink, green and orange.  Because of the potential for many varying factors, the fluorescence of mineral is not typically used for its identification.
  
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[[File:Garnetemr2.jpg|thumb|Garnet]]
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* '''Phosphorescence:'''
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While fluorescent minerals stop glowing when the light source is turned off, minerals that are phosphorescent continue to emit light.  Minerals that can sometimes exhibit phosphorescence are: calcite, celestite, colemanite, fluorite, sphalerite, and willemite.
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* '''Thermoluminescence:'''
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Heating a mineral to temperatures as low as 50-200 degrees Celsius may also produce the emission of light. Some minerals that exhibit thermoluminescence are: apatite, calcite, chlorophane, fluorite, lepidolite, scapolite, and some feldspars.
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* '''Triboluminescence:'''
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Additionally, some mineral may emit light due to a mechanical energy, such as striking, crushing, or scratching.  Potential triboluminescent minerals are: amblygonite, calcite, fluorite, lepidolite, pectolite, quartz, sphalerite, and some feldspars.
  
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== Synonyms and Related Terms ==
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== Examples ==
  
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pyrope (deep red to black); almandine (deep red to black); spessartine (red to brown); grossularite (green); grossular (colorless); carbuncle; andradite (wine red); uvarovite (emerald green); tsavorite (Green); rhodolite (pale red to purple); hessonite (golden); topazolite; demantoid; melanite; Uralian emeralds; Greek anthrax; Granat (Deut.); granate (Esp.); grenat (Fr.); granaat (Ned.); granada (Port.); granatus (Lat.)
 
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== Other Properties ==
 
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Isometric crystal system with dodecahedron and trapezohedron habits. 
 
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Luster = vitreous to resinous.  Fracture = conchoidal or uneven.  Streak = colorless to white
 
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Fluorescence = none (except green ones which may give weak yellow-orange colors)
 
  
 
{| class="wikitable"
 
{| class="wikitable"
 
|-
 
|-
 
! scope="row"| Mineral
 
! scope="row"| Mineral
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| Composition
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| '''Composition'''
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| Visible color
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| '''Visible color'''
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| Fluorescent color
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| '''Fluorescent color'''
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|-
 
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! scope="row"| Agate
 
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| PbCO3
 
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| colorless to white
 
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| yellowish
 
 
|-
 
|-
 
! scope="row"| Apatite
 
! scope="row"| Apatite
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| PbCO3
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| Ca5(PO4)3(F,Cl,OH)
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| colorless to white
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| pale green to purple
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| yellowish
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| pink, blue, greenish yellow
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|-
 
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! scope="row"| Barite
 
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| PbCO3
 
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| colorless to white
 
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| yellowish
 
 
|-
 
|-
 
! scope="row"| Calcite
 
! scope="row"| Calcite
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| PbCO3
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| CaCO3
 
| colorless to white
 
| colorless to white
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| yellowish
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| red, blue, pink, green, orange
 
|-
 
|-
 
! scope="row"| Cerrusite
 
! scope="row"| Cerrusite
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|-
 
|-
 
! scope="row"| Chalcedony
 
! scope="row"| Chalcedony
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| PbCO3
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| SiO2
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| colorless to white
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| white, blue, pink
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| yellowish
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| variable
 
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|-
 
! scope="row"| Corundum
 
! scope="row"| Corundum
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| PbCO3
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| Al2O3
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| colorless to white
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| red (ruby), blue (sapphire)
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| yellowish
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| red (ruby), none (sapphire)
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|-
 
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! scope="row"| Dolomite
 
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| PbCO3
 
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| colorless to white
 
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| yellowish
 
 
|-
 
|-
 
! scope="row"| Fluorite
 
! scope="row"| Fluorite
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| PbCO3
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| CaF2
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| colorless to white
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| colorless, white, pale blue, green
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| yellowish
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| blue-violet
 
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|-
 
! scope="row"| Quartz
 
! scope="row"| Quartz
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| SiO23
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| SiO2
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| colorless to white
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| colorless, purple
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| red
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| variable
 
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|-
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! scope="row"| Rhyolite
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! scope="row"| Scheelite
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| PbCO3
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| CaWO4
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| colorless to white
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| colorless, white, gray brown, yellow, orange, red, green
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| yellowish
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| bright blue, white, yellow
 
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|-
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! scope="row"| Scapolite
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! scope="row"| Sphalerite
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| PbCO3
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| (Zn,Fe)S
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| colorless to white
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| yellow, brown, gray, black
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| yellowish
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| lighter specimens = yellowish
 
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! scope="row"| Willemite
 
! scope="row"| Willemite
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| PbCO3
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| Zn2SiO4
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| colorless to white
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| colorless, white, gray, red, brown
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| green
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| strong white, green
 
|-  
 
|-  
 
|}
 
|}
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[[[SliderGallery rightalign|garnetgrossRS.jpg~Raman]]]
 
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== Additional Information ==
 
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J. Ogden, ''Jewelry of the Ancient World'', Rizzoli International Publications, New York, 1982.
 
  
 
== Comparisons ==
 
== Comparisons ==

Latest revision as of 11:06, 25 July 2022

Fluorescent minerals

Description

Minerals that have the unique physical property to absorb light and one wavelength and instantaneously release it at a different wavelength, resulting in a temporary color change to the eye of the human observer. Only about 15% of minerals are able to fluoresce. The fluorescence is usually due to a cation activator, such as: tungsten, molybdenum, lead, boron, titanium, manganese, uranium, and chromium, but some rare earth elements are also able to contribute to the phenomenon. Some trace elements, such as iron or copper, can quench the fluorscence. Most minerals fluoresce a single color, but some may have multiple colors; for example calcite can fluoresce red, blue, white, pink, green and orange. Because of the potential for many varying factors, the fluorescence of mineral is not typically used for its identification.

  • Phosphorescence:

While fluorescent minerals stop glowing when the light source is turned off, minerals that are phosphorescent continue to emit light. Minerals that can sometimes exhibit phosphorescence are: calcite, celestite, colemanite, fluorite, sphalerite, and willemite.

  • Thermoluminescence:

Heating a mineral to temperatures as low as 50-200 degrees Celsius may also produce the emission of light. Some minerals that exhibit thermoluminescence are: apatite, calcite, chlorophane, fluorite, lepidolite, scapolite, and some feldspars.

  • Triboluminescence:

Additionally, some mineral may emit light due to a mechanical energy, such as striking, crushing, or scratching. Potential triboluminescent minerals are: amblygonite, calcite, fluorite, lepidolite, pectolite, quartz, sphalerite, and some feldspars.

Examples

Mineral Composition Visible color Fluorescent color
Apatite Ca5(PO4)3(F,Cl,OH) pale green to purple pink, blue, greenish yellow
Calcite CaCO3 colorless to white red, blue, pink, green, orange
Cerrusite PbCO3 colorless to white yellowish
Chalcedony SiO2 white, blue, pink variable
Corundum Al2O3 red (ruby), blue (sapphire) red (ruby), none (sapphire)
Fluorite CaF2 colorless, white, pale blue, green blue-violet
Quartz SiO2 colorless, purple variable
Scheelite CaWO4 colorless, white, gray brown, yellow, orange, red, green bright blue, white, yellow
Sphalerite (Zn,Fe)S yellow, brown, gray, black lighter specimens = yellowish
Willemite Zn2SiO4 colorless, white, gray, red, brown strong white, green

Comparisons

Properties of Common Abrasives

Properties of Common Gemstones

Natural and Simulated Diamonds

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