Difference between revisions of "Fluorite"
From The Gemology Project
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[[image:Green_fluorite_massive.jpg|left|thumb|220px|Green Fluorite<br /> Westmoreland, New Hampshire]] | [[image:Green_fluorite_massive.jpg|left|thumb|220px|Green Fluorite<br /> Westmoreland, New Hampshire]] | ||
[[image:Fluorite_green_facet.jpg|left|thumb|120px|Faceted Green Fluorite; 229 carats]] | [[image:Fluorite_green_facet.jpg|left|thumb|120px|Faceted Green Fluorite; 229 carats]] | ||
− | [[Image:fluorite.JPG|left|framed|Fluorite]]<br clear="left" /> | + | [[Image:fluorite.JPG |left|framed|Fluorite]]<br clear="left" /> |
<br clear="all" /> | <br clear="all" /> | ||
[[image:Yellow_fluorite.jpg|left|thumb|200px|Yellow Fluorite Crystals <br /> Clay Center, Ohio]] | [[image:Yellow_fluorite.jpg|left|thumb|200px|Yellow Fluorite Crystals <br /> Clay Center, Ohio]] | ||
− | [[image:Yellow_faceted_fluorite.jpg|left|200px|Yellow Fluorite]] | + | [[image:Yellow_faceted_fluorite.jpg|left|thumb|200px|Yellow Fluorite Faceted <br /> 847.4 carats and 84.7 carats ]] |
+ | [[image:Green_fluor_facet.jpg |left|thumb|150px| Yellowish Green Fluorite]] | ||
<br clear="all" /> | <br clear="all" /> | ||
==Diagnostics== | ==Diagnostics== |
Latest revision as of 14:16, 26 September 2010
Fluorite | |
---|---|
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) |
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).