Chlorophane & Fluorapatite from Franklin, shown under SW UV
Fluorite {CaF2} (variety "chlorophane") - FL teal, SW
Fluorapatite {Ca5(PO4)3F}- FL peach-orange, SW
Willemite {Zn2SiO4}- FL green, SW

"Chlorophane" is the variety of Franklin fluorite that gives an eerie, greenish-blue or teal  luminescence under UV. When you turn off the UV lamps the chlorophane still glows for quite a while. The material is brown to sherry-red in daylight; usually the fresh stuff is more of a sherry color, fading to a dull brown on exposure to sunlight.

Chlorophane will "burn out" or lose its fluorescence if it's exposed to sunlight. This happens rather quickly. A piece of chlorophane sitting on the dump surface can become non-fluorescent within just a few hours of sun exposure-- maybe faster. Therefore, when you break open a rock and find this material inside, it is best to get it out of the light as soon as possible. Some collectors keep this material wrapped in a couple layers of aluminum foil. Then they take the specimens out only once in a while to show people. Don't leave a piece of chlorophane sitting on permanent display under a UV lamp or this, too, will make the fluorescence "burn out". Because its fluorescence is so eerily beautiful, it is still a sought-after mineral by collectors.

This is a newer photograph of one of my chlorophane specimens, showing more true-to-life FL color than I was able to capture before. Even this photo is not a perfect representation-- the real-life response of a fresh chlorophane specimen is really something to behold.

The blue you see in the photograph is just reflected visible light from the UV lamp; the teal color is the actual fluorescence of the chlorophane (fluorite).

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