The Fluorescent Mineral Hobby
Collecting Fluorescent Minerals is an exciting and very satisfying hobby that combines the appreciation of minerals and their unique optical properties.
What Are Fluorescent Minerals?
Fluorescent minerals are those that react to UV, emitting visible light when exposed to ultraviolet (UV) light. This hobby involves collecting, studying, and displaying these fluorescent specimens.
Fluorescent minerals can be found almost anywhere and are often there just for the taking. A spot picked over by daylight mineral rockhounds can be filled with glow rocks at night - the last person never knowing what was left behind.
But there’s more to the hobby than just collecting. We all like to show off our finds. With white light minerals, you just put ‘em on a shelf and shine a light on them. But fluorescent minerals require special setups.
A dark spot, special lights, eye protection, filters, custom cabinets, etc. - the list goes on. But, pay attention to these details and your mineral hobby will be as interesting to others as it is to you.
The Science of Fluorescence in Minerals:
From the Oxford Dictionaries:
"Fluorescence is the visible or invisible radiation produced from certain substances as a result of incident radiation of a shorter wavelength such as X-rays or ultraviolet light."
Fluorescence became known by the middle of the nineteenth century. A British scientist by the name of Sir George G. Stokes first observed fluorescence while examining a piece of fluorspar under ultraviolet light. You will hear about the term “Stokes shift” which describes the difference in wavelength at which a molecule emits light. Fluorescing light has longer wavelengths than the excitation light.
In other words, fluorescence occurs when electrons relax to their ground state (lower energy) after being excited to a higher state by UV light. When they fall back to this lower state, they emit energy as light.
With phosphorescent minerals, the electrons are real slow to fall back into their low energy state, and continue to give off visible light over some period of time after the UV light is turned off.
Fluorescent minerals can emit a range of colors under UV light, including bright yellows, greens, blues, pinks, and oranges. The diverse colors are a result of specific chemical elements or impurities present within the mineral's structure. Some minerals may even exhibit multiple colors under different UV wavelengths. Read more about a mineral’s impurities or “activators” below, where we dive more into detail about this topic.
UV Light Sources:
To observe the fluorescence of minerals, collectors utilize specialized UV light sources, commonly known as "UV lamps" or "UV lights." These lamps emit UV light at specific wavelengths, such as shortwave (254nm), midwave (302nm), or longwave (365nm). The choice of UV light source depends on the minerals being studied or collected.
Displaying Fluorescent Minerals:
Displaying fluorescent minerals is an integral part of the hobby. Collectors often create dedicated displays or showcases that incorporate UV lighting. These displays showcase the minerals in their natural state, as well as their stunning fluorescence when exposed to UV light. The UV illumination brings the minerals to life, creating a captivating and visually striking presentation.
All you need are a bunch of good fluorescent rocks, a piece of furniture that can be turned into a display cabinet, and a reasonably powerful display light. Displays can be shortwave, longwave, midwave, or any combination.
Educational and Scientific Value:
The fluorescent mineral hobby extends beyond aesthetics. It also has educational and scientific value. Fluorescence in minerals can provide insights into their chemical compositions and geological formations. The study of fluorescent minerals contributes to our understanding of mineralogy and can even play a part in the identification of unknown minerals.
Community and Events:
The fluorescent mineral hobby has a vibrant community of enthusiasts who share their knowledge, experiences, and collections. Online forums, websites, and social media groups provide platforms for collectors to connect, discuss, and showcase their finds. There’s a very active and large FaceBook group, Subreddit group and noncommercial website: www.naturesrainbows.com
Additionally, mineral shows and exhibitions often feature fluorescent mineral displays and provide opportunities for collectors to exchange specimens and expand their collections.
The fluorescent mineral hobby offers a unique way to appreciate and explore the beauty and diversity of the mineral kingdom. It combines scientific curiosity, artistic appreciation, and the thrill of discovery. Whether you are a seasoned collector or a newcomer to the hobby, the world of fluorescent minerals offers an exciting journey into a mesmerizing realm of colors and luminescence.
More About Fluorescent Mineral “Activators”
There are around 4,000 different types of minerals – the group consensus is that around 15% of them are known to fluoresce (although with the recent introduction of high power UV lights many new discoveries are being made). Impurities in the mineral (usually) cause this fluorescence - very few “pure” minerals are known to fluoresce. These impurities - “activators” - are the reason for different colors. But the presence of an activator does not mean the mineral will fluoresce - different minerals with the same activator may even fluoresce different colors. Some activators require another “coactivator” to cause fluorescence, and some impurities will quench (prevent) fluorescence. The bottom line - a piece of fluorite from one location may fluoresce brightly while one from another location may not fluoresce at all, or in a very different color.
Known activators include: Manganese, Chromium, Iron, Titanium, Copper, Lead, Europium, Cerium, Uranyl, Tungstate, Molybdate, Sulfur, Nitrogen, and various Organic activators.
The few minerals that fluoresce when pure are called ‘self-activated’ minerals. These include Scheelite, Powellite, and many Uranium minerals. Two of these minerals are perhaps the primary reason the Fluorescent Mineral hobby exists today. Both Scheelite and Uranium were important minerals during WWII. Prospectors used ultraviolet lights to discover deposits of both minerals.
A Sampling Of Fluorescence Caused By Major Activators
Scheelite - a major ore of tungsten, usually is recognized by its brilliant sky-blue fluorescence. Molybdenum as a coactivator modifies the color to white or yellow.
Several secondary uranium minerals, such as autunite, characteristically fluoresce a bright yellowish green. Caused by the uranyl ion, this ion is so prone to fluorescence that trace amounts of it cause yellowish-green fluorescence in a very large number of minerals, including adamite, apophyllite, aragonite, calcite, quartz, and opal.
Willemite - a zinc mineral, usually fluoresces a bright green. This is due to traces of manganese.
Calcite – calcite fluoresces in most all colors due to different activators. Red and pink fluorescent calcites can be activated by lead and manganese. Green fluorescence is due to uranyl ion traces. Calcite from the mercury mines at Terlingua, Texas fluoresces pink under longwave UV and bright blue under shortwave UV. It also has a bright blue phosphorescence after the UV lamp is removed.
Fluorite - fluoresce a blue-violet color due to traces of europium; this is usually best under longwave UV. Fluorite also fluoresces green, yellow, red, and white. Some will fluoresce one color under short-wave, a second color under longwave, and even a third phosphorescence. Other activators in Fluorite include Yttrium, Samarium, and some organic impurities.
Scapolite (or Wernerite) - from Quebec, Canada, fluoresces a vivid yellow color under longwave UV, while short-wave UV causes a bright phosphorescence.
Tugtupite - from Ilimaussaq, Greenland is a rare but beautiful mineral only found in a few places in the world. Under longwave UV light it fluoresces a salmon red color and a deep cherry-red under Short-wave.
Famous Fluorescent Mineral Localities
Franklin, New Jersey - often referred to as the Fluorescent Mineral Capital of the World. Specimens from here are perhaps the brightest and multicolor. Willemite and calcite (red/green) is perhaps the most ubiquitous fluorescent mineral from this locality, known by every glow rock collector.
Ilimaussaq Complex, Greenland - a very new locality first extensively explored for fluorescent minerals in the early 2000's. It has since become a world-class locality. Tugtupite, sodalite (and many hackmanite varieties), chkalovite, and numerous other rare, highly sought after minerals are found here.
Langban, Sweden - similar to Franklin geology, offers spectacular examples of rare minerals. Calcite, svabite, johnbaumite, margarosanite, and many others can be found here and the surrounding area.
The above localities offer great access and easy hunting concentrated in relatively small areas. But fluorescent minerals can be found almost any place you look. Old mine tailings in the western states, along the shores of the great lakes, in the mountains of Peru, mines of Mexico, or maybe even along your local railroad tracks. Did I mention one of my favorites - roadcuts? All you need is a light and darkness.