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Many minerals have the ability to fluoresce. They glow when observed under ultraviolet (UV) light. This enchanting phenomenon occurs due to electrons in atoms of a crystal matrix absorbing energy and then releasing it, emitting light. Many rockhounds use portable UV lights to hunt for fluorescent specimens in the field or to identify glowing specimens in their collection at home.
Using a portable UV light and a thick black plastic tarp while rockhounding in the day, one can identify fluorescent minerals by their glow. You can also search at night. More rocks glow under shortwave UV than longwave UV. Invest in a powerful light that filters out the visible light spectrum.
If the idea of being out rockhounding on a moonless night, with the stars overhead and a glowing pile of ember-like rocks at your feet appeals to you, then UV light rockhounding is the hobby for you! In this article, you will learn why some rocks glow under UV light, what equipment you need to get started, and which UV lights are the best in 2021.
If you are looking for the best UV light for rockhounding only, I and other members of the reputable Facebook group about rockhounding recommend buying Convoy 8+ UV light (Amazon link).
Rocks that Glow in UV Light
All rocks reflect light, but some have the fascinating ability to absorb certain wavelengths of light and then emit a different wavelength.
To the human eye, this temporary change in the light’s wavelength causes the rock to change color. This physical property is known as fluorescence.
The color change is most spectacularly visible as a bright glow when a UV light is used to illuminate the mineral in a dark space.
Which Minerals Fluoresce?
The following minerals all glow different colors under UV light:
- Andalusite – dark green or yellow-green
- Calcite – red
- Eucryptite – pink
- Fluorite or calcium fluoride – blue, green, white, yellow, or red
- Gypsum – blue
- Hyalite or opal – bright green
- Scapolite – yellow, orange, or red
- Scheelite or magnesium tungstate – blue
- Sodalite – orange yellow
- Willemite or zinc silicate – bright green
BTW: Do you want to know more about rock and mineral identification? The books listed below are the best ones you can find on the internet (Amazon links):
- Smithsonian Handbooks: Rocks & Minerals
- Gemstone & Crystal Properties (Quick Study Home)
- Ultimate Explorer Field Guide: Rocks and Minerals (National Geographic Kids)
Use a UV Light for Rockhounding
Take your rockhounding to the next level by taking a UV light along. Invest in a good quality UV light that is powerful, easy to carry, and has a UV filter or LEDs that emit UV light.
Using a UV light while hunting for specimens will add a whole new dimension of fun and intrigue to rockhounding. One can identify specimens in the field by looking at the colors that they glow.
Some experienced rockhounds can see glowing rocks without having to use a UV light – they know what other characteristics to look for. Those new to glow rock hunting should shine a UV light onto a wide variety of minerals to see which fluoresce.
Or simply collect rocks that look interesting to you, take them back home or to where you are camping, and crack them open to inspect them under UV light.
Equipment You Will Need
The equipment you need to start looking for glowing rocks is dependent on your collecting style – whether you collect during the day and at night, and where you inspect your specimens.
These are the basic requirements to get started:
- Portable UV light.
- Batteries.
- Flashlight.
- Geology pick, hammer, and chisel.
- Safety glasses with UV protection, and gloves.
- A black plastic tarp or heavy-duty BBQ cover.
- Fluorescent plastic tape.
- Backpack.
- Good hiking shoes.
TIP: Are you looking for tips on the best tools and equipment for rockhounding? I summarized all tools you need for rockhounding in the article below:
The Complete Guide: All Tools You Need for Rockhounding
What Type of UV Light is Best for Rockhounding?
Firstly, it is important to know that there are three different ranges of UV light:
- Shortwave or SW – 100 to 280nm wavelength
- Mid-wave or MW – 280 to 315nm wavelength
- Longwave or LW – 315 to 400nm wavelength
Some minerals fluoresce under LW UV light, while others only glow under SW UV light. Therefore, you will need a light that has a filter that emits either type of UV light. Mid-wave filters are not necessary.
Most fluorescent minerals glow under SW UV light, so it is great to buy a UV light that has an SW filter. However, these are very expensive – an entry-level one will set you back at least $80.
If you are new to hunting glow rocks it may be better to first buy an LW UV light or blacklight as these are cheaper and they cause plenty of minerals to glow.
You will of course miss a few, but if you are passionate about hunting for fluorescent rocks it is definitely worthwhile saving up for a good SW UV light.
LED UV blacklights that emit wavelengths between 365-395nm are a decent entry-level option, generally costing around $15-20. Torches that emit UV light and visible light make it more difficult to see the fluorescence, so avoid buying these.
With weaker UV torches one will have to hold the light very close to the rock to see the glow, and it is recommended to work in complete darkness, so take a black plastic tarp along to hunt under.
The best type of UV light to use for rockhounding is one that has a glass UV filter that absorbs the visible light spectrum.
These torches are much better suited to rockhounding because they can cause rocks to glow from 2 meters (80 inches) away. They can do this because of the filter that concentrates the UV light.
The 3 Best UV Lights for Rockhounding
These are the top-performing UV lights you can find on the market. They all provide great value for money and are perfect for getting started with UV light rockhounding.
- BEST OPTION: Convoy 8+ 365nm UV LED Flashlight with Patented Glass Filter (Amazon link)
Rockhounds on the popular Facebook group that has over 38 000 members agree that when it comes to UV flashlights for glow rock hunting, this one is the best.
Although it is a lot more expensive than the other torches on our list, it is well worth the price. With its patented glass filter that cuts out visible light, maximizing the percentage of UV light, it can be used to find glowing rocks up to 2 meters away!
It has a tough construction and is waterproof, so it will be safe out in the field with you. Powered by two lithium-ion batteries (which are included when you buy the light), it is easy to keep this fully charged in the field.
Check out the latest prices for this amazing UV light here (Amazon link).
BUDGET OPTION: Karrong Rechargeable 1200 Lumen 395nm UV Flashlight (Amazon link)
This super bright 1200 lumen torch has a UV light setting, among its 7 different modes. It emits 395 nm wavelength UV light, making it ideal for seeing fluorescent rocks that emit LW UV light.
The full metal body is water, rust, and shock resistant, making it durable enough to take into the field. It weighs around 180g, so you will hardly notice the extra weight in your backpack.
This flashlight’s best feature is that it is powered by a rechargeable lithium-ion battery. It has a zoomable lens, to adjust the size and intensity of the light beam.
Check the latest prices for this great UV light here (Amazon link).
OPTION FOR INDOOR USAGE: Prime Upgraded Big Chip 396nm UV LED Light Lamp (Amazon link)
This portable light fixture has a clamp to attach it to a work surface, and a 10-inch long adjustable gooseneck that can rotate 360 degrees.
It has a 5V USB input and can be powered with a power bank or laptop when you are out rockhounding, or from a power outlet with a power supply adapter when you are at home.
The LED light emits 395 nm wavelength UV light, and the light source has 2 Watts of power. Hold rocks very close to the light to inspect them for fluorescence and work in complete darkness.
Check out the latest prices for this great UV light lamp here (Amazon link).
TIP: Are you able to take fluorescent rocks and minerals to the airplane? Find out everything you need to know about flying with rocks in the article below:
Are You Able To Bring Rocks On An Airplane? You Can But…
How to Use a UV Light for Rockhounding
Pack your backpack with all the necessary tools and equipment and head out on a UV light rockhounding adventure!
Find out if there are any abandoned mines with mine dumps or tailing piles in your area. Look for old riverbeds, rocky outcrops, or areas with exposed bedrock. These are reliable spots that offer good hunting.
Rockhounding with a UV light at night can be a lot of fun, but if you have never been to a place before, it is better to go there during the day first.
Mark rocks that you want to look at under UV light with fluorescent plastic tape so that you can easily return to their location in the dark.
There are remote spots where one can find many different types of fluorescent minerals. One such place is Greenland, but that is very far away and expensive to travel to.
Look no further than your own backyard or rock collection! Inspect the rocks that you already have under UV light to see if any of them are fluorescent.
Use a geology pick, or a hammer and chisel to break rocks in half to see the most vibrant luminescence. When rock is exposed to air it oxidizes and weathers, developing a “rind” that kills luminescence. Crack a rock to expose a fresh face. This will glow the brightest.
Indoor Usage of UV Lights
As a rockhound, you probably already have piles of rocks at home that you have collected. Find out if any of them are fluorescent by shining a UV light on them!
An advantage of inspecting fluorescence at home is that you can use a much more powerful light, as it does not have to be battery-operated or portable.
If you do not have a very powerful torch, start by darkening a room to work in, or work at night when it is very dark.
Set up your UV light, and before turning it on, put on a pair of UV-protected safety glasses and gloves. Switch on the UV light, hold it close to a mineral specimen, and see if it glows.
Outdoor Usage of UV Lights
Hunting for glow rocks is pretty similar to hunting for other rocks, except that it requires darkness. You can either go rockhounding at night, or you can carry a thick black plastic tarp or a heavy-duty BBQ cover with you to create artificial darkness in the field. The material needs to be thick to be able to block out bright sunlight.
Remember to wear UV-protected glasses, gloves, and sunblock during the day and at night if you are using a powerful UV light!
Visit a good hunting spot during the day and look for interesting features you want to return to at night. Mark them with some fluorescent plastic tape so that they are easy to find in the dark. Shine a UV light onto a mineral from a short distance away and see if it glows.
Alternatively, crouch down on the ground with the mineral specimen in front of you. Throw a thick black plastic tarp or BBQ cover over yourself to create a dark little tent. Inside, shine the UV light onto the rock in front of you and see if it glows.
TIP: Fluorite is one of the fluorescent minerals. But you can find a lot of fake fluorites on the internet. To avoid missunderstandings when buying fluorites, read the article below and find out the main differences between real and fake fluorites:
Real vs. Fake Fluorite: Focus on These 5 Differences
Safety Considerations When Using UV Light
Rockhounds that are new to hunting with UV lights may be unaware of some of the dangers of UV light. Just as UV rays from the sun can burn our skin, UV rays from shortwave or longwave UV light can burn our eyes. They are powerful, concentrated sources of UV rays.
It is crucial never to look directly into a UV light. Wear long sleeves, gloves, and sunblock when working with UV light. Wear safety glasses that have UV protection.
If you do not take the necessary precautions, your eyes will feel like there is sand in them. Supervise young Rock Pups and teach them to be careful with UV lights.
It is also important to remember that some fluorescent rocks glow because they contain uranyl atoms, and therefore are radioactive. Treat these minerals with respect and handle them with care.
Wear good hiking shoes and use a quality head torch, especially when rockhounding at night. Many great places to look for glowing rock specimens are difficult to navigate in the dark, and rock piles, cliffs, and tailings can make for slippery terrain.
Good Locations to Hunt for Glow Rocks
Finding a good spot is usually the biggest challenge. First start looking for rocks that fluoresce in places you have been to and know is good for rock hunting. Look for places where there is exposed bedrock, like in creeks or dry riverbeds.
Abandoned mines, mine dumps, and tailing piles are always good starting points. Try to find out from local people what type of mine it was. Apatite, barite, calcite, fluorite, selenite, and scheelite mines usually have amazing glowing rocks.
Join a local geology club to get more information about good places in your area for rock collecting. There is a large and active community of fluorescent rock collectors on the internet. If there is not a club in your area, join one online.
There are many Facebook groups, like the Fluorescent Mineral Group, where rockhounds from around the world help each other find collecting spots, share glow rock hunting tips, and review UV lights.
TIP: Creeks or rivers are great places for finding glow rocks. Do you know what the most common rocks you can find there are? Check out the articles below:
Seven Most Common Types of Rocks Found in Creeks
Ten Most Common Types of Rocks You Can Find In Rivers
Best Locations in the World to Find Glowing Rocks
One of the best places for rockhounds to hunt for fluorescent specimens is the Ilimaussaq Complex in Greenland. It is world-renowned for having a diversity of glowing rocks.
The Buckwheat Dump in Franklin, New Jersey, and the mines in Arizona are famous for almost every rock being fluorescent. There are also mine dumps in Langban, Sweden where almost every rock you find is fluorescent.
Conclusion
Rockhounding with a UV light enables you to find fluorescent rocks that glow a different color when exposed to UV light. Collecting fluorescent rocks is an easy yet exciting hobby.
Powerful SW UV lights are rather expensive, so if you are just getting into this as a new hobby, consider buying an LW UV light.
There are high-quality LED UV flashlights on the market that emit wavelengths between 365-395nm. These work well on freshly cracked rocks, in a dark environment with the light close to the specimen.
Hunting for glowing rocks can be done during the day or at night. During the day, you need to create a dark tent, so carry a thick black plastic tarp or heavy-duty BBQ cover with you to work under.
So if you are interested in buying the best UV light for rockhounding, my 3 picks are (Amazon links):
- BEST OPTION: Convoy 8+ 365nm UV LED Flashlight with Patented Glass Filter
- BUDGET OPTION: Karrong Rechargeable 1200 Lumen 395nm UV Flashlight
- OPTION FOR INDOOR USAGE: Prime Upgraded Big Chip 396nm UV LED Light Lamp
TIP: Minerals and rocks can completely change their colors by being subjected to UV light or black light. Check out the common minerals and rocks that glow under UV light in the article below:
12 Rocks & Minerals That Glow Under UV Light & Black Light