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Geosciences LibreTexts

16.36: Fluorite

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Fluorite
Chemical composition CaF2alcium fluoride
Crystal system Cubic
Habit Octahedral, cubes, interpenetrant twins
Cleavage Perfect, octahedral
Fracture Conchoidal
Hardness 4
Optic nature Isotropic
Refractive index 1.434
Birefringence Isotropic
Dispersion Very low, 0.007
Specific gravity 3.18
Lustre Poor vitreous
Fluorescence Bluish-white, purple (LW)

File:Fluorite barite galena.jpg

Figure \(\PageIndex{1}\): Fluorite with Barite and Galena
Elmwood Mine, Carthage, Tennessee

File:Fluorite sphalerite barite.jpg

Figure \(\PageIndex{2}\): Fluorite with Sphalerite and Barite
Elmwood Mine, Carthage, Tennessee

File:Faceted fluorite.jpg

Figure 16.36.3: Faceted purple fluorite

File:Green fluorite massive.jpg

Figure 16.36.4: Green Fluorite
Westmoreland, New Hampshire

Figure 16.36.5: Faceted Green Fluorite; 229 carats

Figure 16.36.6: Fluorite

File:Yellow fluorite.jpg

Figure 16.36.7: Yellow Fluorite Crystals
Clay Center, Ohio

Figure 16.36.8: Yellow Fluorite Faceted
847.4 carats and 84.7 carats

File:Green fluor facet.jpg

Figure 16.36.9: Yellowish Green Fluorite

Diagnostics

Thermoluminescence

Fluorite may luminesce when heated. The stored energy from UV radiation is released if heated to a certain temperature and the effect depends on the amount of stored energy.
One can see this when a small amount of fluorite is placed on a teaspoon and heated over a candle for a few minutes (in a dark room).
Material from Telemark, Norway will show a blue-green thermoluminescence.

Optical phenomena

Color change

Color change fluorite has been reported with a change from blue to purple (much like some color change garnet).


This page titled 16.36: Fluorite is shared under a CC BY-NC-SA 2.5 license and was authored, remixed, and/or curated by gemology via source content that was edited to the style and standards of the LibreTexts platform.

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