Many minerals and chemical compound display triboluminescence, which is light produced when chemical bonds are broken. Two minerals that exhibit triboluminescence are diamond and quartz. The procedure to produce the light is so simple, you should try it right now! Feel free to use diamonds, but be aware the light is produced when the crystal lattice is damaged. Quartz, on the other hand, is the most abundant mineral in the Earth's crust, so you should probably start with that.
Quartz Triboluminescence Materials
You need any form of quartz, which is crystalline silicon dioxide (SiO2). You don't have to sacrifice perfect quartz crystal points for this project! Most gravel contains quartz. Play sand is mostly quartz. Go outside and find two semitranslucent rocks. Chances are good they are quartz.
How to See the Light
- First, make sure the quartz is dry. The phenomenon occurs when the crystal lattice is torn apart by friction or compression. Wet quartz is slippery, so its presence will compromise your efforts.
- Gather your materials in a darkened location. It doesn't need to be pitch black, but light levels need to be low. Give your eyes a couple of minutes to adjust to make it easier to see the flashes of light.
- Method 1: Firmly rub together two pieces of quartz. See the flashes of light?
- Method 2: Strike one piece of quartz with another. Now, you may also get actual sparks using this method, plus you may chip off splinters of rock. Use eye protection if you go this route.
- Method 3: Walkthrough dry sand. This works well at a beach or in a sandbox, but the sand must be dry or else the water will cushion the crystals.
- Method 4: Crush a piece of quartz using pliers or a vise. This method is especially nice if you want to take a video of your project.
- Method 5: Do what the Uncompahgre Ute did and fill a translucent rattle with bits of quartz. Shake the rattle to see the glow. The native tribes used rattles made of rawhide, but a plastic bottle works fine, too.
How Quartz Triboluminescence Works
Triboluminescence sometimes is called "cold light" because no heat is produced. Material scientists believe the light results from a recombination of electrical charges that become separated when crystals are fractured. When the charges get back together, the air is ionized, producing a flash of light. Usually, materials that display triboluminescence are displayed an asymmetrical structure and are poor conductors. This is not a hard-and-fast rule, however, since other substances display the effect. It's not restricted to inorganic materials, either, since triboluminescence has been observed between vertebral joints, during blood circulation, and even during sexual intercourse.
If it's true the light results from ionization of air, you might expect all forms of triboluminescence in the air to produce the same color of light. However, many materials contain fluorescent substances that release photons when excited by the energy from triboluminescence. Thus, you can find examples of triboluminescence in just about any color.
More Ways to See Triboluminescence
Rubbing together diamonds or quartz is not the only easy way to observe triboluminescence. You can view the phenomenon by pulling apart two pieces of duck tape, by crushing wintergreen candies, or by pulling the Scotch tape from its roll (which also produces x-rays). The triboluminescence from the tape and the candies is a blue light, while the light from fracturing quartz is a yellow-orange.
Orel, V.E. (1989), "Triboluminescence as a biological phenomenon and methods for its investigation", Book: Proceedings of the First International School Biological Luminescence: 131-147.