Glow in the Dark Crystals

Electromagnetic radiation and photons are the same thing. When we use UV lights, we are bombarding minerals with electromagnetic radiation within the Ultraviolet range. There are three different lights we use in the mineral world UVA, UVB and UVC. UVA is safe for humans and penetrates tempered glass displays. You will notice your teeth, finger nails, eyes and sometimes socks glowing as they react to it. UVB and UVC are halted by tempered glass- which is a good thing since they are dangerous to humans and so too are the progressive wavelengths of electromagnetic radiation as the frequencies become shorter- reaching what movie characters would refer to as “critical radiation levels!”.

As the molecules of our minerals become excited due to the excess energy provided by the UV lights, they give off their own photons hence the term “Fluorescence”. Just like how water molecules, when excited, give off heat, The stone molecules must balance the extra energy input from the UV lamps. They do this by emitting their own photons within the visible spectrum, and in doing so- adhering to the first law of thermodynamics. Thus, in a dark room, the only light source you’ll see is coming from the rocks themselves- which are glowing.

UV light is not visible to humans, however the bulbs we use are not perfect. In addition to emitting UV light, they are often emitting some light within the visible spectrum. Low value lamps will for this reason “pollute” a display with visible light. Whereas, the higher value lamps will have special filters installed in the fixture that refine the light output to a desired spectrum- such as 254nm for UVC.

The Spectrum

Radio Waves

+100 kilometers to 1 millimeter

Radio and television broadcasting, communication, radar.

SCALE: Building/Human


1 meter to 1 millimeter

Cooking, radar, telephone, and other signals.

SCALE: Bumble Bee


1 mm (millimeter) to 0.001 mm
(0.001 mm = 1000 nm (nanometer)

Thermal imaging, remote controls, heat lamps, infrared photography.

SCALE: Pinpoint

Near Infrared

1000 to 750 nm (nanometers)

Remote sensing, agriculture, food analysis, medical diagnostics, optical fiber communication.

Visible Light

750 nanomaters (nm) to 400 nm

Human vision, photography, optical communication.

SCALE: Bacteria


UVA Long Wave 400 - 315 nm
UVB Medium Wave 315 - 280 nm
UVC Short Wave 280 - 200 nm

Absorbed by the skin, used in fluorescent tubes.

SCALE: Molecule


10 nanometers (nm) to 0.01 nm

Medical imaging, airport security scanners, materials testing.


Gamma Rays

Less than 0.01 nanometers

Medical imaging, radiation therapy, astrophysics.

SCALE: Atomic Nuclei



While causing minimal genetic damage to tissues, UVA radiation can also lead to sunburn through its shorter wavelengths. Roughly 95% of the sun’s UVA rays reach Earth, making exposure to a UVA lamp almost equivalent to being outdoors.

Penetrates tempered glass.
Blocked by 0P3 Acrylic.


While only 5% of the sun’s UVB rays breach the ozone layer and reach the Earth, UVB is the primary culprit for sunburn and skin cancers. Sunburn is a sign of short-term overexposure, while premature aging and skin cancer are side effects of prolonged UV exposure. Avoid looking directly at a UVB light source to avoid sunburning your eyes.

Blocked by tempered glass and OP3 Acrylic.


UVC radiation can cause severe burns of the skin and eye injuries (photokeratitis). Avoid direct skin exposure to UVC radiation and never look directly into a UVC light source, even briefly. Skin burns and eye injuries from UVC exposure usually resolve within a week with no known long-term damage. Due to UVC’s shallow penetration, the chances of skin cancer, cataracts, or permanent vision loss are considered low. UVC-related eye injuries (welder’s flash) result in intense pain and a gritty sensation, potentially affecting vision for 1-2 days, even after brief exposure.

Blocked by tempered glass and OP3 Acrylic. *Damage from UV exposure is cumulative. The degree of damage depends on the intensity of UV rays and the length of time your skin has been exposed without protection.

Flourescence vs Phosphorescence

Fluorescence and phosphorescence are captivating behaviors exhibited by certain minerals when exposed to light. In fluorescence, these minerals swiftly absorb ultraviolet or visible light and promptly emit it, often in a different colour. It’s a vivid response to a temporary burst of energy. This effect, seen in minerals like fluorite and calcite, creates a striking glow under specific lighting conditions. Fluorescence typically ceases nanoseconds to microseconds once the light source is removed.

Phosphorescence, in contrast, extends the drama. When certain minerals absorb light, they hold onto that energy, releasing it more gradually over time. This lingering luminosity, observed in minerals such as willemite and sphalerite, is akin to a gentle afterglow. Phosphorescent materials store energy and release it at a leisurely pace. Phosphorescence persists seconds, minutes or even hours after initial excitation.

When you hold a phosphorescent stone such as the Red River selenites from Manitoba, charge them and then remove the light, it will feel like you are holding a ball of energy. The delayed emissions appear paradoxical and the stuff of science fiction—much like holding an illuminated lightbulb that is not plugged in.

Glow-in-the-dark materials are often phosphorescent. The materials absorb light and then release it slowly over time, making them visible in the dark.

Why is it Called A “Black” Light

The color we perceive as black is fundamentally the absence of any light frequencies of the visible spectrum. Although black lights emit light, ultraviolet light is not visible to human eyes, so the light is "black" as far as your eyes are concerned. A light that only gives off ultraviolet light would leave a room in apparent total darkness.

How Many Rocks Glow

There are just over 5000 known mineral varieties. Fluorescence or phosphorescence can be detected with scientific equipment in about 700 of those. The number of “interesting" reactive minerals is far fewer. A fluorescent mineral display’s beauty comes from the magnificent show of colours, and there are many that can glow vividly. There are also many that do not. Their glow reaction to the UV light will be dull in either emission of photons or colour saturation.

The most common minerals on the global market that fluoresce are aragonites, calcites, chalcedonies, fluorites, hackmanites, hyalite opals, rubies, and sodalites. Next are the region- specific minerals such as ones from the township of Franklin, New Jersey (USA) and Greenland. There are still other obscure mineral varieties that aren’t commonly seen nor readily available at gem shows and rock shops.

Trace Elements

These elements can interact with the crystal lattice of minerals or compounds, leading to energy transitions that result in fluorescence. Keep in mind that the specific fluorescent properties can vary widely depending on chemical composition, crystal structure, and impurities present in the material.

Various trace elements from the periodic table can cause phosphorescence or fluorescence. The presence of certain elements as impurities in materials can lead to phosphorescent behavior.

F = Fluorescence

P = Phosphorescence

S Sulfur
U Uranium
Sn Tin
Th Thorium
Zn Zinc
Cu Copper
Cr Chromium
Pb Lead
Mn Manganese
Fe Iron
Ag Silver
Bi Bismuth
Co Colbalt
Ln Lanthides
Alkali Metals
Earth Metals

Applications in the World Today

The ability of materials to fluoresce has a broad range of applications across various fields. Here’s a list of some scientific, industrial, and artistic purposes for harnessing fluorescence.

Decorative and Artistic Applications

Fluorescent materials are used in artistic creations, such as paintings, sculptures, and installations, to enhance visual impact.

Environmental Monitoring

Fluorescent compounds can be used to detect and quantify pollutants and contaminants in air, water, and soil.

Fluorescent Lighting

Fluorescent lighting is widely used for energy-efficient lighting in various settings.


Fluorescent materials can highlight ancient artifacts and help decipher historical clues.

Fluorescence Spectroscopy

This technique is used to analyze the composition of materials based on their fluorescence properties, aiding in chemical and material analysis.

Security Features

Fluorescent inks and pigments are used in currency, official documents, and products to incorporate hidden security elements.

Biomedical Imaging

Fluorescent dyes and markers are used In microscopy, helping visualize cellular structures and biological processes.

Educational Tools

Fluorescent demonstrations help explain scientific concepts, engaging students and enhancing learning experiences.

Material Testing

Fluorescence can indicate material defects, stress points, and structural changes, aiding in quality control and testing.

Photography and Cinematography

Fluorescent materials can be used to create special effects, props, and costumes in visual arts.

Mineralogy and Geology

Fluorescence helps identify and differentiate minerals, aiding mineralogists and geologists in specimen analysis and exploration.

Food and Beverage Industry

Fluorescence can be used to detect contaminants or quality issues in food and beverages.

Optical Filters and Sensors

Fluorescent materials are used in optical filters and sensors for various applications, including those used in environmental monitoring and medical devices.


Fluorescence in gemstones can influence their appearance, value, and identification in the field of gemology.

Forensic Analysis

Fluorescent substances are used to enhance the visibility of latent fingerprints and trace evidence.

Medical Diagnostics

Fluorescent probes can be designed to target specific molecules or cells, facilitating disease detection and diagnosis.

Pharmaceutical Research

Fluorescent labeling is used in drug discovery and research to study molecular interactions and cellular processes.

Environmental Studies

Fluorescence is used to study marine and aquatic life, as well as monitor changes in ecosystems.