From The Gemology Project
Jump to: navigation, search
Chemical composition CaF2

Calcium 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)
Fluorite with Barite and Galena
Elmwood Mine, Carthrage, Tennessee
Fluorite with Sphalerite and Barite
Elmwood Mine, Carthrage, Tennessee
Faceted purple fluorite

Green Fluorite
Westmoreland, New Hampshire
Faceted Green Fluorite; 229 carats

Yellow Fluorite Crystals
Clay Center, Ohio
Yellow Fluorite Faceted
847.4 carats and 84.7 carats
Yellowish Green Fluorite



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).