FMF - Friends of Minerals Forum, discussion and message board

[cascaillou]

A brief overview of what would be possible with fluorite:

TREATMENTS:

As for any mineral specimens, one might consider the possibility of specimen repairs or even fabrications (i.e. crystals glued on non-original matrix), as well as surface polishing, acid etching, or even carving of the crystals (as an example, those carved fluorite "loops", let's also mention that those loose fluorite octahedrons often seen for sale are obtained by cleavage).

As for any commercially successful stone, one might consider the possibility of surface coatings or fracture filling with either colorless or coloured materials such as dyes, varnish, oils, or polymer resin (with the purpose of improving luster and transparency and/or of improving or modifying the color).

Such treatments can be detected.

Now, in regard of heat and irradiation treatments of fluorite:
-Lightening the color through gentle heating (for instance excessively dark blue to lighter blue, or purple to a more pink shade). Excessive heating would turn the fluorite colorless (which would then be reversible by irradiation).
-Creating a kind of red from heating some blue fluorites (this was reported but unconfirmed).
-Darkening the color through irradiation (for instance light blue to stronger blue).
-Creating blue, purple, green, or other colors from colorless or pale coloured (for instance pale green or pale yellow) fluorite through irradiation (obtained color as well as the stability of the color in time will depend on starting material). Also reported, obtaining a blue color with color-change effect (purple in incandescent light).

Heat treatment and irradiation treatment are impossible to prove or disprove, even with lab analysis (although in a case of overheating, maybe microscopic examination of solid and fluid inclusions could possibly reveal it?)

SYNTHETICS:

Synthetic fluorite is being produced, and it can be produced in various colors (either through dopants, or through subsequent irradiation treatment).

Synthetic fluorite is mostly grown for optical applications. Currently, this is usually done through Czochralski pulling, Bridgman-Stockbarger, and gradient solidification methods, which are melt processes yielding cylindrical crystals (thus not looking anything like natural fluorite crystals). Although, it would still be possible to obtain an octahedron through cleavage, or to cut a cube (and then make it appear a bit more natural by carving or acid etching its surface).

SIMULANTS:

There would be a variety of possible imitations for massive and banded fluorite (i.e. plastic and resins, glass and ceramics, dyed aragonite/calcite/marble, dyed alabaster, dyed quartzite, dyed quartz, etc.).
Visually, massive fluorite could possibly be confused with massive amethyst or apatite.
Visually again, coloured artificial crystals of salt or alums (of K, Cr, Fe, etc.) could vaguely imitate fluorite crystals (note that these compounds are water soluble and have taste).
Faceted/cabbed fluorite could possibly be imitated with plastic, glass, ceramics, glass-ceramics, or synthetic lithium fluoride (as well as any of the dyed materials mentioned previously).
For faceted or cabbed stones, as always, composite stones (i.e. doublets or triplets) are also a possibility.