Fluorite

Fluorite is a very popular mineral and can occur natural in any color, being one of the most variate mineral on earth.
Pure Fluorite is colorless, any Fluorite which present colors are from impurities.
Sometimes colors are caused by hydrocarbonates and can be removed by heating the mineral.

Fluorite is the first mineral to present fluorescent, having a blue glow when is illuminated with ultraviolet light.
Many fluorite specimens are strong enough to show a observable glow as such that if we too the fluorite outside to the sun light and then we observe it under shadow, we will see a change in color.
The fluorescence in fluorite is caused by the presence of yttrium, europium, samarium or other organic matter and activators.
Fluorite's fluorescence is mostly blue but can also be red, violet, yellow, green or white.

Chemical formula CaF2
Composition: 51,33% calcium; 48,67% fluorine
Density: 3,01-3,25; average 3,13
Color: colorless (crystal clear), white, purple, violet, blue, red, pink, green, brown, gray or black and can have multicolored bands
Streak - white
Hardness 4 Mohs
Crystal system: isometric, looks like cubic system
Crystal forms: octahedral and cubic; crystals can make combinations of octahedral and cubic with dodecahedral in complex and interesting forms
Cleavage 1, all sides
Transparent to translucid
Fracture concoidal
Type of rocks: igneous, sedimentary, metamorphic

Special characteristics:
-can have a variety of fluorescence colors
-can present phosphorescence
-presents thermoluminocence when the mineral is heated to 100 Celsius / 212 Fahrenheit
-can show triboluminocence

Tests:
Hardness: 4 Mohs, has white streak
Fluorescence blue, violet, green, yellow, white, red
Red and green fluorite can become phosphorescent when heated at more then 100 Celsius / 212 Fahrenheit
Thermoluminocence
Triboluminocence

Varieties of Fluorite:
Antozonite - a variety of fluorite which have uncombined ions, when is fractured, has an specific odor.
Blue John - lines of purple and white or purple and yellow, a variety of fluorite
Chlorophane - a variety of fluorite which shows thermoluminocence, emanating powerful green light when is heated
Yttrocerite - a variety of fluorite in which elements like cerium or yttrium partially replace the calcium in it's chemical structure, showing the next formula: (Ca, Ce, Y)F2
Yttrofluorite - a variety of fluorite in which element yttrium partially replace the calcium in it's chemical structure, having the formula (Ca, Y)F2

Asociated minerals:
Calcite, quartz, barite, galena, pyrite, chalcopyrite

Distinguishing similar minerals:
Calcite - a little softer, 3 Mohs and have different crystal forms
Quartz - a lot harder, 7 Mohs, has no cleavage
Apatite - a little harder, 5 Mohs, has different crystal forms
Halite - a lot softer, 2-2,5 Mohs, has salt taste

A pyramid of fluorite:

A piece of fluorite

Luminescence of fluorite:
UV types:
 Long wave (365 nm) in general blue, others: white blue, white yellow, yellow, brown, red, green, white pale green, purple, white blue, blue-purple, yellow-pink
Mid wave (320 nm) in general blue, others:  green
Short wave (254 nm) in general blue, others: white blue, white yellow, yellow, brown, red, green, white pale green, purple, white blue, blue-purple, yellow-pink

Phosphorescence: in long wave UV, white-green, with strong intensity but rare in crystals
Presents triboluminoscence and thermoluminoscence.

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 n red and other colors (in longwave UV)

Activators: the most common: Eu
Others: organic impurities, Sm, Eu, Dy, Ho, Er, Tb, Nd
Spectrum:
Eu replace Ca: 423-425 nm (purple)
Sm replace Ca: 707, 733 nm
Ub replace Ca: 550 nm
Dy: 468, 478, 575, 654, 658, 663, 671, 685 nm
Tb: 482, 484, 486, 492, 539, 543, 544, 546, 588 nm
Er: 519, 522, 528, 551, 554 nm
Sm: 561 nm
Eu: 574, 595, 618, 622, 700 nm
Nd: 920
2F+Na+: 720-745 nm
Spectre: http://www.fluomin.org/galeriespectre/spectre.php?lg=fr&name=FLUORITE

Sources:
https://www.minerals.net/mineral/fluorite.aspx
https://www.mindat.org/min-1576.html
http://webmineral.com/data/Fluorite.shtml#.XaiOw-gzbvM
http://www.fluomin.org/uk/fiche.php?id=29&name=FLUORITE

Other names: fluor , fluorspar , fluorit , fluorina fluorite