I am not a specialist in fluorescent minerals. But in my years as a rock dealer I have seen many fantastic dark room displays of rocks glowing in all colors of the rainbow! Many times when the UV light (Ultaviolet) is switched off and the regular lights switched on, the minerals are very unexciting and not colorful at all.
I do have a UV light and I like to check out some minerals now and then (as well as the scorpionsaround here!).
Often I am asked if one of the minerals I sell on ebay will fluoresce. The truth is-I don't usually know. But I thought it would be fun to privide some basic information for the beginner collector.
Fluorescence is caused by the incorporation of small metal impurities in the mineral. These impurities often affect the color of the mineral. Copper can make a mineral green or blue, magnese can make them purple or pink, etc. Some of the trace minerals that fluoresce are chromium, maganese, cobalt, nickel, tungsten, etc. Because each mineral may contain a variety of these metals, not all minerals that are the same, will fluoresce the same. Fluoresce can help indentify a mineral, but is actually more reliable in determining a origin as many deposits have very distinct fluorescence. If iron is is present in any amount-it will prevent fluorescence!
The word "fluorescence" comes from the mineral fluorite, which was the mineral on which this light phenomenon was first discovered. Of course, strangely enough, only a little of fluorite responds to UV light! Minerals are displayed under a UV light with both long waves and short waves, as some will only fluoresce under one type of wave. The strength of the glow and the colors vary greatly. Sometimes the glow will persist even after the UV light has been turned off. This effect is called phosphorescence.
Scheelite, or calcium tungsten, is one of the few rare minerals that always fluoresces, no matter where it came from. This is why tungsten wire is used in light bulubs.
Here is a partial list of fluorescent minerals and their common reactions:
Agate-can be strong, usually yellow or blue-white
Amazonite-weak, usually olive green
Amethyst-weak, usually greenish
Calcite-can be red, pink, orange, white, or yellow-white
Fluorite-usually strong, blue to violet
Lapis Lazuli-strong, white
Rose Quartz-weak, dark violet
Scheelite-blue,whitish, or yellow
Sphalerite-usually yellow to orange, sometimes red
Tourmaline-can be colorless to weak, or many other colors
Turquoise-weak, greenish-yellow, light blue
Thank you for your interest. Please visit my ebay store to see lots of Mineral Specimens and Rocks! If you want to know if something fluoresces-just ask!