Fluorescence

Fluorescence is the propriety of a mineral to emit light when is illuminated with ultraviolet light.
Fluorescence happen when an electron of an atom is hit by a high energy photon and its orbit jumps to a higher orbit absorbing the photon. After that, the electron will jump back to its orbit but the energy accumulated will be released by heat and another photon.
On phosphorescence, the electrons jump more orbits higher and will fall slowly each orbit until its gets to the original orbit, releasing light over time.
Fluorescence happens (the drop of the electron to its original orbit) typically in just 10 nanoseconds but phosphorescence can last seconds to minutes or even more.
When higher energy light hits a mineral, if that minerals contains some specific activators (impurities), then it will convert some of the incoming light to another, less energetic light.
Ultraviolet light is usually the best way to show this effect.
Ultraviolet light has a wavelength from 10 to 400 nm and is sometimes called black light, UV light.
It is categorized in three types:
LW UVA Long wavelength, from 315 to 400 nm, it is not dangerous but care should be taken.
MW UVB Mid wavelength, from 280 to 315 nm, it is dangerous and can cause skin burns and eye problems so care should be taken.
SW UVC Short wavelength, from 100 to 280 nm, it very dangerous and is used for sterilization in medicine.

Over 500 minerals show fluorescence when exposed to UV light.

Higher temperature can stop fluorescence, making the conversion of light to happen faster and even surpres it; some minerals can amplify the fluorescence effect by heating or cooling.

Fluorescence at cold temperatures: minerals like Scapolite and some feldspars can fluorescence lighter when they are cooled.

Just 15% of all minerals present fluorescence visible for humans.

Types of luminescence:

• Fluorescence is the conversion of high energy light to low energy light.
  An mineral illuminated with UV light can glow with a specific color but when the source of light is turned off, the glow will also be terminated.
  Minerals: Agate and many more, see the list down.

• Phosphorescence is the delay of conversion of light, when a mineral is hit with high energy light, the electrons will drop slowly from their orbitals thus glowing for more time even after the source of light was turned off.
  Phosphorescence minerals: Calcite, Celestine, Colemanite, Fluorite, Sphalerite, Willemite.

Calcite showing green phosphorescence after the UV light was turned off, it lasts for seconds.

• Polarized fluorescence, an effect observed in Calcite.
  Illuminating the mineral with UV light, will emit two polarized light with each having different wave rotation, one 90 degree of the other.
  This effect can be observed as double refraction in transparent Calcite.

• Thermoluminoscence: is a characteristic of emitting light when heated.
  The effect can appear from 50 degree Celsius up to 200 degree Celsius. (122 Fahrenheit to 392 Fahrenheit)
  Minerals with thermoluminoscence: Apatite, Calcite, Chlorophane, Fluorite, Lepidolite, Scapolite, Feldspars

• Triboluminoscence: minerals emitting light when crush or scratch or even rubbed.
  These minerals contains elements that emits light when kinetic force is detected.
  Minerals: Calcite, Fluorite, Lepidolite, Pectolite, Quartz, Sphalerite, Feldspars, Amblygonite, Micas.
• Tenebrescence or photochromacity, is an effect of changing color or darkening a mineral's color after it was exposed to UV light, the efect will be temporaly and last a bit even after the UV light was turned off.
  The efects happen with natural light too, when an alexandrite crystal is exposed to natural light will have a different color than exposed to artificial light.
  The effect will be destroyed by heating and cannot be repeated more after.
  Some chemicals that change colors are neodymium fluoride, neodymium chloride and glass with neodymium oxide.
  Minerals are: Tugtupite, Hackmanite, Sodalite, Spodumene, Alexandrite
• Different from fluorescence but interestingly enough, Incandescence is when a material glows and emits light after it is heated.
  Almost any material will glow when is heated over 500 degree Celsius

Fluorescence is caused by activators, which are impurities that cause fluorescence and are not present on any mineral from the same species. Fluorite usually has fluorescence but is not a must.
Some activators may need a second one for the effect to work.

Fluorescence is not limited to UV or visible light, some minerals can absorb light and convert it as infrared light, also x-ray can act as higher energy than fluorescence.
Synthetic minerals have more powerful effect because of the controlled way of including the precise activators.

Some elements can cancel the fluorescence caused by activators.
And if the activator is in hight quantities, it can lower or stop the fluorescence effect.
Thus for a mineral to present fluorescence, it has to have a specific and balanced quantity of an activator.

Activators in generals are: tungsten, molybdenum, lead, boron, titanium, manganese, uranium and chrome.
There are others but these are the generals one.
More rare activators are Europium, Terbium, dysprosium and yttrium.
Organic impurities can usually cause fluorescence.

Duo activators: manganese produce red fluorescence but only when lead is present; lead's electrons absorbs the UV light and transfers it to the manganese which emits visible light.

The fluorescence of minerals:

• Calcite, Willemite, Wollastonite, Esperite, Clinohedrite:
  Manganese in concentrations of several procents, is responsible of red or orange fluorescence in calcite, green in willemite, yellow in esperite, orange in wollastonite and chlinohedrite.
  Calcite has a rainbow of colors when fluorescence in all long, mid and shortwave UV.
  Calcite can also have a green phosphorescence.
  Willemite is a zinc silicate and known for extremely bright green fluorescence and can also have other colors and yellow or white in shortwave.
  Wollastonite, many specimens are fluorescent and vary in colors from deep yellow in short wave to magenta or mustar (orange) under long or mid wave UV.

• Ruby, Corundum, Sapphires:
  Ruby has a red fluorescence because of small quantities of chromium.
  If a ruby has iron, it will absorbs the UV light and emits it as heat and vibrations instead of light.
  Rubbies are largely found in masses of both fuchsite and zoisite.

• Zoisite - calcium aluminium hydroxy sorosilicate from epidote group, can have orange fluorescence in long wave
• Phosgenite - a soft mineral with bright orange fluorescence
• Fluorite
  The general source of fluorescence is Europium, having a blue glow.
  Many fluorite specimens does not emit fluorescence.
  Other causes for fluorescence in Fluorite is yttrium, europium, samarium or organic material.
  Florite can rarely fluoresence in red and other colors (in longwave UV)

• Vaterite - poliform of calcite, can have white-blue fluorescence
• Yttrofluorite
  Lanthanides, terbium and dysprosium are the primary activators for yellow fluorescence in yttrofluorite, a variety of fluorite.

• Powellite (calcium molybdate) and Scheelite (calcium tungstate) have yellow and blue fluorescence.
  When they are pressed together in a solid solution, the energy is transferred from tungsten with high energy to low energy molybdenum, and thus low levels of molybdenum are sufficient to cause yellow glow for scheelite instead of blue.

• Sphalerite:
  Some minerals can emit different colors under UV, blue in short wave and red in long wave.
  A zinc sulfite, usualy comes with pyrite covering it and giving a red fluorescence to it.
  Mostly orange fluorescence but can have a rainbow of colors.
  Can also be triboluminescent.
• Emerald, Morganite and Beryl - can have none to weak fluorescence
• Tourmaline - can have weak fluorescence
• Spodumene:
  Can have different colors from blue in shortwave to red in long wave.
• Oceanic jasper:
  Can have may colors from blue to dark red, yellow and green and can differ from dark red under long UV to yellow under short UV and the green ones under short UV to pale green under long wave UV.
• Apatite:
  It is composed of several minerals from the group of phosphates, including fluorapatite, hydroxylapatite and chlorapatite.
  Fluorapatite is the most common variety and can be found in both prismatic crystal and massive habits, with a various colors, will have mostly dark yellow or violet in UV.
• Aragonite:
  A very common carbonate mineral, similar to calcite, often formed through precipitation in both salt and fresh water environments.
  Has a yellow, white or bluish fluorescence with a white or greenish phosphorescence in long and short UV.

In the left is a sphere of aragonite showing phosphorescence after the UV light was turned off;

In the middle is a yellow jasp and in the left is a non-phosphorescent yellow calcite

• Baryte / Barite:
  Is a barium sulfate mineral that typically can be found as tubular crystals.
  Has a yellow fluorescence and may phosphorescence strongly greenish-white in long wave UV.
• Celestine - a strontium sulfate, from baryte group
• Diamonds:
  Fluorescence in diamonds decreases its value because that means it has impurities.
  Diamonds will have sometimes blue or pink fluorescence.
• Cerussite:
  Is a lead carbonate and often has fluorescence with yellow color in long wave UV.
• Chalcedony:
  A variety of quartz, consists of microscopic crystals of quartz and sometimes moganite.
  Sometimes has a green fluorescence, rarely yellow or white, in short wave UV.
• Esperite:
  Found only in two locations, Esperite is a rare and often associated with willemite, calcite and hardystonite.
  Has a yellow fluorescence in shortwave UV
• Hardystonite:
  Is a calcium zinc silicate minerale, very rare with a deep blue fluorescence.
• Hyalite:
  It is known as water-clean opal, is a clean form of opal and is extremely fluorescent, glowing very bright green. Some of the brightest specimens are from North Carolina, Hungary and Namibia, hyalite from Zacatecas, Mexico was found to be fluorescent in sunlight.
• Hydrozincite:
  A zinc carbonate formed typically as an oxidation of zinc ores.
  Has a bluish white fluorescent in short wave UV
• Opal:
  A common form of oppal that doesnt show any fire or iridescence, glow typicaly bright green with the activator being uranyl ions.
  Rarely can glow yellow
• Pyromorphite:
  Some specimens may have a powerfull orange fluorescence or mustar yellow under mid wave UV
• Scapolite:
  It is a group of aluminosilicate minerals that includes meionite and marialite or wernerite and mizzonite.
  Can have yellor or red fluorescence
• Scheelite:
  Is a calcium tungstate, it is an important source of tungsten,
  Has a bluish white, rarely red in mid and short wave UV
• Selenite:
  Is a crystalized form of gypsum.
  Can have a bluish white under UV and can also have phosphorescence for seconds.
• Smithsonite:
  A zinc carbonate, common associations includes willemite, hemimorphite, cerusssite and fluorapatite.
  Has a red fluorescence.
• Sodalite:
  A variety of sodalite called hackmanite exhibits tenebrescence, an effect that makes the crystal darker after is exposed to UV light, the effect will stay after the UV light is turned off and is a temporary effect.
  Can have an orange glow under UV.
• Tremolite:
  Manganocummingtonite (Tirodite), anthophyllite and tremolite are indistinguishable and all members of the amphibole group of silicates.
  Has a red to yellow fluorescence in short wave UV
• Tugtupite:
  Is a rare beryllium aluminum tectosilicate and is bright under UV light.
  Has red in shortwave and orange in longwave UV
  Exhibits tenebrescence.
• Caliche:
  It is not a mineral but a mineral deposit, a natural cement of calcium carbonate and can have alot of colors under UV from orange to grayish white and multicolored.
  Can have phosphorescence
• Autunite:
  Light green fluorescence, Autunite is radioactive.
• Uranocircite:
  Light green fluorescence but very radioactive.

Phosphorescence
Materials used for phosphorescence in toys or industrial, includes zinc sulfide and strontium aluminate.
Zinc sulfide in nature is found as Sphalerite but is added activators for the effect (typically 0,0005% copper ions activator Cu+) with a green phosphorescence.
Adding a second activator to that, Cobalt Co+, will double the glow time.
Strontium aluminate is the most used in makeup and trafic lights and has brighter effect and longer duration and many colors like orange, green, red, blue, turquoise, dark blue.
Strontium aluminate is activated with silver activator.
Activator can lose its power over time because of oxidation effect.
In old watches, radium was used together with phosphorescence to get a permanent glow for several years without exposure to light.
The glow was lost over time not because of the decay being finished but because the radiation alters the composition of the phosphor composition.
Other uses of phosphor and its composition:
https://en.wikipedia.org/wiki/Phosphor

Florescent liquids:
Fluorescein - light green fluorescence
Rhodamine B - dark red fluorescence
Other fluorescence materials: white cloth, detergents, safety vests, transparent lego peaces, plastics, paper etc.
Screens also uses fluorescent material like Terbium (green fluorescence) and Europium (red-pink fluorescence).
CRT TVs also have fluorescence material on the screen.

Colors in wavelength
https://simple.wikipedia.org/wiki/Visible_spectrum
http://pages.cs.wisc.edu/~yetkin/code/wavelength_to_rgb/wavelength.html
Sources:
http://www.fluomin.org/uk/listIMA.php?liste=1